46 CFR 154.447 - Allowable stress.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 5 2014-10-01 2014-10-01 false Allowable stress. 154.447 Section 154.447 Shipping COAST... Tank Type B § 154.447 Allowable stress. (a) An independent tank type B designed from bodies of revolution must have allowable stresses 3 determined by the following formulae: 3 See Appendix B for stress...

46 CFR 154.447 - Allowable stress.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 5 2013-10-01 2013-10-01 false Allowable stress. 154.447 Section 154.447 Shipping COAST... Tank Type B § 154.447 Allowable stress. (a) An independent tank type B designed from bodies of revolution must have allowable stresses 3 determined by the following formulae: 3 See Appendix B for stress...

46 CFR 154.428 - Allowable stress.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Allowable stress. 154.428 Section 154.428 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR... § 154.428 Allowable stress. The membrane tank and the supporting insulation must have allowable stresses...

46 CFR 154.428 - Allowable stress.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false Allowable stress. 154.428 Section 154.428 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR... § 154.428 Allowable stress. The membrane tank and the supporting insulation must have allowable stresses...

46 CFR 154.428 - Allowable stress.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 5 2013-10-01 2013-10-01 false Allowable stress. 154.428 Section 154.428 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR... § 154.428 Allowable stress. The membrane tank and the supporting insulation must have allowable stresses...

46 CFR 154.428 - Allowable stress.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 5 2014-10-01 2014-10-01 false Allowable stress. 154.428 Section 154.428 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR... § 154.428 Allowable stress. The membrane tank and the supporting insulation must have allowable stresses...

46 CFR 154.428 - Allowable stress.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 5 2012-10-01 2012-10-01 false Allowable stress. 154.428 Section 154.428 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR... § 154.428 Allowable stress. The membrane tank and the supporting insulation must have allowable stresses...

A Review & Assessment of Current Operating Conditions Allowable Stresses in ASME Section III Subsection NH

DOE Office of Scientific and Technical Information (OSTI.GOV)

R. W. Swindeman

2009-12-14

The current operating condition allowable stresses provided in ASME Section III, Subsection NH were reviewed for consistency with the criteria used to establish the stress allowables and with the allowable stresses provided in ASME Section II, Part D. It was found that the S{sub o} values in ASME III-NH were consistent with the S values in ASME IID for the five materials of interest. However, it was found that 0.80 S{sub r} was less than S{sub o} for some temperatures for four of the materials. Only values for alloy 800H appeared to be consistent with the criteria on which S{submore » o} values are established. With the intent of undertaking a more detailed evaluation of issues related to the allowable stresses in ASME III-NH, the availabilities of databases for the five materials were reviewed and augmented databases were assembled.« less

46 CFR 64.13 - Allowable stress; tank.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Allowable stress; tank. 64.13 Section 64.13 Shipping... CARGO HANDLING SYSTEMS Standards for an MPT § 64.13 Allowable stress; tank. (a) The calculated stress in... not exceed the allowable stress listed in Division 1 of section VIII of the ASME Code, for a design...

46 CFR 64.13 - Allowable stress; tank.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Allowable stress; tank. 64.13 Section 64.13 Shipping... CARGO HANDLING SYSTEMS Standards for an MPT § 64.13 Allowable stress; tank. (a) The calculated stress in... not exceed the allowable stress listed in Division 1 of section VIII of the ASME Code, for a design...

46 CFR 64.13 - Allowable stress; tank.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Allowable stress; tank. 64.13 Section 64.13 Shipping... CARGO HANDLING SYSTEMS Standards for an MPT § 64.13 Allowable stress; tank. (a) The calculated stress in... not exceed the allowable stress listed in Division 1 of section VIII of the ASME Code, for a design...

46 CFR 64.13 - Allowable stress; tank.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Allowable stress; tank. 64.13 Section 64.13 Shipping... CARGO HANDLING SYSTEMS Standards for an MPT § 64.13 Allowable stress; tank. (a) The calculated stress in... not exceed the allowable stress listed in Division 1 of section VIII of the ASME Code, for a design...

46 CFR 64.13 - Allowable stress; tank.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Allowable stress; tank. 64.13 Section 64.13 Shipping... CARGO HANDLING SYSTEMS Standards for an MPT § 64.13 Allowable stress; tank. (a) The calculated stress in... not exceed the allowable stress listed in Division 1 of section VIII of the ASME Code, for a design...

46 CFR 64.15 - Allowable stress; framework.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Allowable stress; framework. 64.15 Section 64.15... AND CARGO HANDLING SYSTEMS Standards for an MPT § 64.15 Allowable stress; framework. The calculated stress for the framework must be 80 percent or less of the minimum yield stress of the framework material...

46 CFR 64.15 - Allowable stress; framework.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Allowable stress; framework. 64.15 Section 64.15... AND CARGO HANDLING SYSTEMS Standards for an MPT § 64.15 Allowable stress; framework. The calculated stress for the framework must be 80 percent or less of the minimum yield stress of the framework material...

46 CFR 64.15 - Allowable stress; framework.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Allowable stress; framework. 64.15 Section 64.15... AND CARGO HANDLING SYSTEMS Standards for an MPT § 64.15 Allowable stress; framework. The calculated stress for the framework must be 80 percent or less of the minimum yield stress of the framework material...

46 CFR 64.15 - Allowable stress; framework.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Allowable stress; framework. 64.15 Section 64.15... AND CARGO HANDLING SYSTEMS Standards for an MPT § 64.15 Allowable stress; framework. The calculated stress for the framework must be 80 percent or less of the minimum yield stress of the framework material...

46 CFR 64.15 - Allowable stress; framework.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Allowable stress; framework. 64.15 Section 64.15... AND CARGO HANDLING SYSTEMS Standards for an MPT § 64.15 Allowable stress; framework. The calculated stress for the framework must be 80 percent or less of the minimum yield stress of the framework material...

Allowable stress in piles.

DOT National Transportation Integrated Search

1983-12-01

"This study presents methods for establishing allowable stresses in steel, concrete, and timber piles using load/resistance factor concepts. These methods take into account not only the material properties of the pile itself but also the individual e...

49 CFR 230.25 - Maximum allowable stress on stays and braces.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Maximum allowable stress on stays and braces. 230... Boilers and Appurtenances Allowable Stress § 230.25 Maximum allowable stress on stays and braces. The maximum allowable stress per square inch of net cross sectional area on fire box and combustion chamber...

Allowable compressive stress at prestress transfer.

DOT National Transportation Integrated Search

2008-12-01

In 2004, The Texas Department of Transportation initiated Project 5197 to investigate the feasibility of : increasing the allowable compressive stress limit at prestress transfer. Initially, the live load performance of 36 : specimens was evaluated b...

Evolution of allowable stresses in shear for lumber

Treesearch

Robert L. Ethington; William L. Galligan; Henry M. Montrey; Alan D. Freas

1979-01-01

This paper surveys research leading to allowable shear stress parallel to grain for lumber. In early flexure tests of lumber, some pieces failed in shear. The estimated shear stress at time of failure was generally lower than shear strength measured on small, clear, straight-grained specimens. This and other engineering observations gave rise to adjustments that...

49 CFR 230.25 - Maximum allowable stress on stays and braces.

Code of Federal Regulations, 2012 CFR

2012-10-01

... maximum allowable stress per square inch of net cross sectional area on fire box and combustion chamber stays shall be 7,500 psi. The maximum allowable stress per square inch of net cross sectional area on...

49 CFR 230.25 - Maximum allowable stress on stays and braces.

Code of Federal Regulations, 2014 CFR

2014-10-01

... maximum allowable stress per square inch of net cross sectional area on fire box and combustion chamber stays shall be 7,500 psi. The maximum allowable stress per square inch of net cross sectional area on...

49 CFR 230.25 - Maximum allowable stress on stays and braces.

Code of Federal Regulations, 2011 CFR

2011-10-01

... maximum allowable stress per square inch of net cross sectional area on fire box and combustion chamber stays shall be 7,500 psi. The maximum allowable stress per square inch of net cross sectional area on...

49 CFR 230.25 - Maximum allowable stress on stays and braces.

Code of Federal Regulations, 2013 CFR

2013-10-01

... maximum allowable stress per square inch of net cross sectional area on fire box and combustion chamber stays shall be 7,500 psi. The maximum allowable stress per square inch of net cross sectional area on...

Progress Report on Alloy 617 Time Dependent Allowables

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wright, Julie Knibloe

2015-06-01

Time dependent allowable stresses are required in the ASME Boiler and Pressure Vessel Code for design of components in the temperature range where time dependent deformation (i.e., creep) is expected to become significant. There are time dependent allowable stresses in Section IID of the Code for use in the non-nuclear construction codes, however, there are additional criteria that must be considered in developing time dependent allowables for nuclear components. These criteria are specified in Section III NH. St is defined as the lesser of three quantities: 100% of the average stress required to obtain a total (elastic, plastic, primary andmore » secondary creep) strain of 1%; 67% of the minimum stress to cause rupture; and 80% of the minimum stress to cause the initiation of tertiary creep. The values are reported for a range of temperatures and for time increments up to 100,000 hours. These values are determined from uniaxial creep tests, which involve the elevated temperature application of a constant load which is relatively small, resulting in deformation over a long time period prior to rupture. The stress which is the minimum resulting from these criteria is the time dependent allowable stress St. In this report data from a large number of creep and creep-rupture tests on Alloy 617 are analyzed using the ASME Section III NH criteria. Data which are used in the analysis are from the ongoing DOE sponsored high temperature materials program, form Korea Atomic Energy Institute through the Generation IV VHTR Materials Program and historical data from previous HTR research and vendor data generated in developing the alloy. It is found that the tertiary creep criterion determines St at highest temperatures, while the stress to cause 1% total strain controls at low temperatures. The ASME Section III Working Group on Allowable Stress Criteria has recommended that the uncertainties associated with determining the onset of tertiary creep and the lack of significant

Allowable bending stresses of wood for use in portable wood ladders

Treesearch

Fred Werren

1975-01-01

A standard for portable wood ladders has been in effect since 1923, and has been revised several times since then. The most recent publication is "American National Standard Safety Standard for Portable Wood Ladders," A14.1-1975, from American National Standards Institute, Inc. Methods of arriving at allowable stresses for wood ladder parts have never been...

Fiber stress values for design of glulam timber utility structures

Treesearch

R. Hernandez; R. C. Moody; R. H. Falk

In this study, we developed a simple equation to calculate average fiber stress values for design of glued-laminated (glulam) timber utility structures as a function of design bending stress. We took design stress in bending values specified by the American Institute of Timber Construction (AITC) for various combinations of glulam timber, applied appropriate end-use...

Teaching High-Value Pronunciation Features: Contrastive Stress for Intermediate Learners

ERIC Educational Resources Information Center

Levis, John M.; Levis, Greta Muller

2018-01-01

Pronunciation features are not equal in how they affect listeners' ability to understand. Some are low value, while others are high value. This study explores whether contrastive stress is high value. Previous research has shown that identification of contrastive stress is learnable (Pennington & Ellis, 2000), and that explicit teaching about…

Relationship Between Earthquake b-Values and Crustal Stresses in a Young Orogenic Belt

NASA Astrophysics Data System (ADS)

Wu, Yih-Min; Chen, Sean Kuanhsiang; Huang, Ting-Chung; Huang, Hsin-Hua; Chao, Wei-An; Koulakov, Ivan

2018-02-01

It has been reported that earthquake b-values decrease linearly with the differential stresses in the continental crust and subduction zones. Here we report a regression-derived relation between earthquake b-values and crustal stresses using the Anderson fault parameter (Aϕ) in a young orogenic belt of Taiwan. This regression relation is well established by using a large and complete earthquake catalog for Taiwan. The data set consists of b-values and Aϕ values derived from relocated earthquakes and focal mechanisms, respectively. Our results show that b-values decrease linearly with the Aϕ values at crustal depths with a high correlation coefficient of -0.9. Thus, b-values could be used as stress indicators for orogenic belts. However, the state of stress is relatively well correlated with the surface geological setting with respect to earthquake b-values in Taiwan. Temporal variations in the b-value could constitute one of the main reasons for the spatial heterogeneity of b-values. We therefore suggest that b-values could be highly sensitive to temporal stress variations.

Allowable Stresses For Use in Dynamic Analysis of PF-4 Fire Suppression System Piping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menefee, Maia Catherine; Salmon, Michael W.

The purpose of this paper is to present the results of a limited test program performed on samples of fittings removed from the PF-4 fire suppression system and to present recommendations for allowable stresses to be used in subsequent piping analysis.

46 CFR 54.10-5 - Maximum allowable working pressure (reproduces UG-98).

Code of Federal Regulations, 2010 CFR

2010-10-01

... section VIII of the ASME Boiler and Pressure Vessel Code, together with the effect of any combination of... operating temperature, using for each temperature the applicable allowable stress value. Note: Table 54.10-5...

Dependency of the injection induced seismicity b-value on the stress state of existing fractures

NASA Astrophysics Data System (ADS)

Mukuhira, Y.; Fehler, M. C.; Ito, T.; Asanuma, H.; Häring, M. O.

2017-12-01

The Gutenberg-Richter distribution of earthquake is a power law relationship and it holds for laboratory scale earthquakes (acoustic emission) to subduction zone earthquakes as well as induced seismicity. The gradient of the power law is known as the b-value, which can be considered the ratio of the number of the larger earthquakes to small ones. Larger earthquakes are often observed in low b-value regions, or alternatively a b-value reduction has been observed before some main shocks. Some authors have argued that b-value is negatively correlated with differential stress level. Therefore, a b-value anomaly found in time-space analysis may be used for detection of an area of stress concentration and used for earthquake prediction or hazard risk assessment. In the field of induced seismicity where b-value reduction has also been observed, the physical mechanism of b-value reduction has not been understood well. Since induced seismicity related with fluid injection usually occurs at depths around 1000 5000 m, a significant tectonic mechanism to cause a stress concentration during a short time of hydraulic stimulation might not be expected. We used borehole analysis and focal mechanism information to investigate the stress state on the existing fractures that caused induced seismicity. Then we divide the catalog into the groups with varying normalized shear stress threshold and estimated the b-value. We found that b-value for the events that occurred along higher shear stress fractures were significantly lower (figure 1a) than those from the moderate/lower shear stress fractures (figure 1b). Thus, b-value dependency on the shear stress can be observed for induced seismicity on a reservoir scale. Therefore, we propose that the reason for the observed b-value reductions in induced seismicity on a reservoir scale is the events that occur along higher shear stress fractures. Supposing that the earthquakes occurs along well-orientated fractures, the b-value dependence on

Stress attenuates the flexible updating of aversive value

PubMed Central

Raio, Candace M.; Hartley, Catherine A.; Orederu, Temidayo A.; Li, Jian; Phelps, Elizabeth A.

2017-01-01

In a dynamic environment, sources of threat or safety can unexpectedly change, requiring the flexible updating of stimulus−outcome associations that promote adaptive behavior. However, aversive contexts in which we are required to update predictions of threat are often marked by stress. Acute stress is thought to reduce behavioral flexibility, yet its influence on the modulation of aversive value has not been well characterized. Given that stress exposure is a prominent risk factor for anxiety and trauma-related disorders marked by persistent, inflexible responses to threat, here we examined how acute stress affects the flexible updating of threat responses. Participants completed an aversive learning task, in which one stimulus was probabilistically associated with an electric shock, while the other stimulus signaled safety. A day later, participants underwent an acute stress or control manipulation before completing a reversal learning task during which the original stimulus−outcome contingencies switched. Skin conductance and neuroendocrine responses provided indices of sympathetic arousal and stress responses, respectively. Despite equivalent initial learning, stressed participants showed marked impairments in reversal learning relative to controls. Additionally, reversal learning deficits across participants were related to heightened levels of alpha-amylase, a marker of noradrenergic activity. Finally, fitting arousal data to a computational reinforcement learning model revealed that stress-induced reversal learning deficits emerged from stress-specific changes in the weight assigned to prediction error signals, disrupting the adaptive adjustment of learning rates. Our findings provide insight into how stress renders individuals less sensitive to changes in aversive reinforcement and have implications for understanding clinical conditions marked by stress-related psychopathology. PMID:28973957

Adaptive tuning of mutation rates allows fast response to lethal stress in Escherichia coli

PubMed Central

Swings, Toon; Van den Bergh, Bram; Wuyts, Sander; Oeyen, Eline; Voordeckers, Karin; Verstrepen, Kevin J; Fauvart, Maarten; Verstraeten, Natalie; Michiels, Jan

2017-01-01

While specific mutations allow organisms to adapt to stressful environments, most changes in an organism's DNA negatively impact fitness. The mutation rate is therefore strictly regulated and often considered a slowly-evolving parameter. In contrast, we demonstrate an unexpected flexibility in cellular mutation rates as a response to changes in selective pressure. We show that hypermutation independently evolves when different Escherichia coli cultures adapt to high ethanol stress. Furthermore, hypermutator states are transitory and repeatedly alternate with decreases in mutation rate. Specifically, population mutation rates rise when cells experience higher stress and decline again once cells are adapted. Interestingly, we identified cellular mortality as the major force driving the quick evolution of mutation rates. Together, these findings show how organisms balance robustness and evolvability and help explain the prevalence of hypermutation in various settings, ranging from emergence of antibiotic resistance in microbes to cancer relapses upon chemotherapy. DOI: http://dx.doi.org/10.7554/eLife.22939.001 PMID:28460660

[Contrast agent improves diagnostic value of dobutamine stress echocardiography].

PubMed

Uehara, H; Yamamoto, T; Hirano, Y; Ozasa, Y; Yamada, S; Ikawa, H; Ishikawa, K

2001-03-01

Suboptimal endocardial definition reduces the diagnostic value of stress echocardiography for coronary artery disease, but intravenous infusion of a left ventricular contrast agent (Albunex) may enhance endocardial border delineation and improve the diagnostic value of dobutamine stress echocardiography. Fifty-six patients, 38 with myocardial infarction, 16 with angina pectoris and two normal subjects, were enrolled in this study. Dobutamine was infused in scalar doses of 5 to 40 micrograms/kg/min. Intravenous infusion of Albunex (0.15 ml/kg) was administered at rest and during peak dobutamine stress during monitoring of the apical four-chamber view. The left ventricle in the apical four-chamber view was divided into six segments and an endocardial delineation score of 0 to 3 (none to excellent visualization) was given to each segment. Endocardial delineation score was increased after Albunex infusion from 2.0 to 2.3 in the basal-septal, 2.0 to 2.4 in the mid-septal, 1.1 to 1.8 in the apical-septal, 0.7 to 1.2 in the apical-lateral, 0.9 to 1.6 in the mid-lateral, and 1.2 to 1.9 in the basal-lateral segments during peak dobutamine administration. Endocardial border resolution in the lateral wall showed greater improvement than in the septal wall after Albunex infusion. Diagnostic values in the left anterior descending artery territory failed to improve with Albunex infusion (sensitivity 82% to 89%, specificity 94% to 89%, and accuracy 86% to 89%), whereas a higher diagnostic accuracy was noted in the left circumflex artery territory with Albunex compared to without Albunex (sensitivity 63% to 81%, specificity 88% to 98%, and accuracy 80% to 93%, p < 0.05). Contrast agent improves the diagnostic accuracy of dobutamine stress echocardiography in the left circumflex artery territory.

Allowing and Using Foods of Low Nutritional Value in Elementary School Classrooms: The Implications of Teachers' Beliefs.

PubMed

Lambert, Laurel G; Chang, Yunhee; Varner, Jennifer; Monroe, Ann

2016-02-01

To investigate elementary teachers' behavior toward allowing and using foods with low nutritional value in the classroom. A survey guided by the Theory of Planned Behavior was administered in fall, 2012 in 10 schools. Elementary public school teachers in grades pre-kindergarten through 6. Teachers' behavior and beliefs regarding allowing and using foods with low nutritional value in the classroom and Theory of Planned Behavior determinants. Pairwise correlation coefficients and multivariate linear regression to assess relationships between theory determinants and descriptive statistics. All 3 determinants, Attitude Toward the Behavior (t = 4.04; P < .01), Subjective Norms (t = 3.78; P < .01), and Perceived Behavioral Control (t = 5.19; p < .01), were statistically significant predictors of behavior. The majority of teachers (94%) allowed foods of low nutritional value for celebrations at least some of the time, and 75% stated that they had control over what foods they allow. Discussions among teachers and school health professionals should ensue to improve nutritional content of foods allowed in classrooms. School policies can be developed and evaluated for effectiveness to have a positive impact on childhood obesity and school nutrition environments. Copyright © 2016 Society for Nutrition Education and Behavior. Published by Elsevier Inc. All rights reserved.

Manipulating environmental stresses and stress tolerance of microalgae for enhanced production of lipids and value-added products-A review.

PubMed

Chen, Bailing; Wan, Chun; Mehmood, Muhammad Aamer; Chang, Jo-Shu; Bai, Fengwu; Zhao, Xinqing

2017-11-01

Microalgae have promising potential to produce lipids and a variety of high-value chemicals. Suitable stress conditions such as nitrogen starvation and high salinity could stimulate synthesis and accumulation of lipids and high-value products by microalgae, therefore, various stress-modification strategies were developed to manipulate and optimize cultivation processes to enhance bioproduction efficiency. On the other hand, advancements in omics-based technologies have boosted the research to globally understand microalgal gene regulation under stress conditions, which enable further improvement of production efficiency via genetic engineering. Moreover, integration of multi-omics data, synthetic biology design, and genetic engineering manipulations exhibits a tremendous potential in the betterment of microalgal biorefinery. This review discusses the process manipulation strategies and omics studies on understanding the regulation of metabolite biosynthesis under various stressful conditions, and proposes genetic engineering of microalgae to improve bioproduction via manipulating stress tolerance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of increasing the allowable compressive stress at release on the shear strength of prestressed concrete girders.

DOT National Transportation Integrated Search

2008-09-01

In recent years, several research projects have been conducted to study the feasibility of increasing the allowable : compressive stress in concrete at prestress transfer, currently defined as 0.60f'ci in the AASHTO LRFD Bridge : Design Specification...

The effect of lavender oil on stress, bispectral index values, and needle insertion pain in volunteers.

PubMed

Kim, Sioh; Kim, Hyun-Jae; Yeo, Jin-Seok; Hong, Sung-Jung; Lee, Ji-Min; Jeon, Younghoon

2011-09-01

The purpose of this study was to investigate whether lavender oil aromatherapy can reduce the bispectral index (BIS) values and stress and decrease the pain of needle insertion in 30 volunteers. Thirty (30) healthy volunteers were randomly allocated to 2 groups: the experimental group received oxygen with a face mask coated with lavender oil for 5 minutes, and the control group received oxygen through a face mask with no lavender oil for 5 minutes. The stress level (0=no stress, 10=maximum stress), BIS value, and pain intensity of needle insertion (0=no pain, 10=worst pain imaginable) were measured. There were no significant differences in age, sex, height, and weight between the two groups. Stress level, BIS value, and pain intensity of needle insertion before aromatherapy were similar between the two groups. However, the stress values (p<0.001) and BIS value (p<0.001) after aromatherapy were significantly reduced compared with the control. In addition, the pain intensity of needle insertion was significantly decreased after aromatherapy compared with the control (p<0.001). Lavender aromatherapy in volunteers provided a significant decrease in the stress levels and in the BIS values. In addition, it significantly reduced the pain intensity of needle insertion.

30 CFR 1206.109 - When may I take a transportation allowance in determining value?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 3 2013-07-01 2013-07-01 false When may I take a transportation allowance in determining value? 1206.109 Section 1206.109 Mineral Resources OFFICE OF NATURAL RESOURCES REVENUE, DEPARTMENT OF THE INTERIOR NATURAL RESOURCES REVENUE PRODUCT VALUATION Federal Oil § 1206.109 When may I take a...

30 CFR 1206.109 - When may I take a transportation allowance in determining value?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 3 2012-07-01 2012-07-01 false When may I take a transportation allowance in determining value? 1206.109 Section 1206.109 Mineral Resources OFFICE OF NATURAL RESOURCES REVENUE, DEPARTMENT OF THE INTERIOR NATURAL RESOURCES REVENUE PRODUCT VALUATION Federal Oil § 1206.109 When may I take a...

30 CFR 1206.109 - When may I take a transportation allowance in determining value?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 3 2014-07-01 2014-07-01 false When may I take a transportation allowance in determining value? 1206.109 Section 1206.109 Mineral Resources OFFICE OF NATURAL RESOURCES REVENUE, DEPARTMENT OF THE INTERIOR NATURAL RESOURCES REVENUE PRODUCT VALUATION Federal Oil § 1206.109 When may I take a...

Microalgae for high-value compounds and biofuels production: a review with focus on cultivation under stress conditions.

PubMed

Markou, Giorgos; Nerantzis, Elias

2013-12-01

Microalgal biomass as feedstock for biofuel production is an attracting alternative to terrestrial plant utilization for biofuels production. However, today the microalgal cultivation systems for energy production purposes seem not yet to be economically feasible. Microalgae, though cultivated under stress conditions, such as nutrient starvation, high salinity, high temperature etc. accumulate considerable amounts (up to 60-65% of dry weight) of lipids or carbohydrates along with several secondary metabolites. Especially some of the latter are valuable compounds with an enormous range of industrial applications. The simultaneous production of lipids or carbohydrates for biofuel production and of secondary metabolites in a biorefinery concept might allow the microalgal production to be economically feasible. This paper aims to provide a review on the available literature about the cultivation of microalgae for the accumulation of high-value compounds along with lipids or carbohydrates focusing on stress cultivation conditions. © 2013.

Hsp90 and environmental stress transform the adaptive value of natural genetic variation.

PubMed

Jarosz, Daniel F; Lindquist, Susan

2010-12-24

How can species remain unaltered for long periods yet also undergo rapid diversification? By linking genetic variation to phenotypic variation via environmental stress, the Hsp90 protein-folding reservoir might promote both stasis and change. However, the nature and adaptive value of Hsp90-contingent traits remain uncertain. In ecologically and genetically diverse yeasts, we find such traits to be both common and frequently adaptive. Most are based on preexisting variation, with causative polymorphisms occurring in coding and regulatory sequences alike. A common temperature stress alters phenotypes similarly. Both selective inhibition of Hsp90 and temperature stress increase correlations between genotype and phenotype. This system broadly determines the adaptive value of standing genetic variation and, in so doing, has influenced the evolution of current genomes.

Racial-Ethnic Disparities in Maternal Parenting Stress: The Role of Structural Disadvantages and Parenting Values

PubMed Central

Nomaguchi, Kei; House, Amanda N.

2013-01-01

Although researchers contend that racial-ethnic minorities experience more stress than whites, knowledge of racial-ethnic disparities in parenting stress is limited. Using a pooled time-series analysis of data from the Early Childhood Longitudinal Study, Kindergarten Class of 1998–99 (n = 11,324), we examine racial-ethnic differences in maternal parenting stress, with a focus on structural and cultural explanations and variations by nativity and child age. In kindergarten, black mothers, albeit U.S.-born only, report more parenting stress than white mothers due to structural disadvantages and authoritarian parenting values. The black-white gap increases from kindergarten to third grade, and in third grade, U.S.-born black mothers’ higher stress than white mothers’ persists after controlling for structural and parenting factors. Hispanic and Asian mothers, albeit foreign-born only, report more stress than white mothers at both ages due to structural disadvantages and authoritarian values. Despite structural disadvantages, American Indian mothers report less stress. PMID:24026535

Racial-ethnic disparities in maternal parenting stress: the role of structural disadvantages and parenting values.

PubMed

Nomaguchi, Kei; House, Amanda N

2013-01-01

Although researchers contend that racial-ethnic minorities experience more stress than whites, knowledge of racial-ethnic disparities in parenting stress is limited. Using a pooled time-series analysis of data from the Early Childhood Longitudinal Study, Kindergarten Class of 1998-99 (n = 11,324), we examine racial-ethnic differences in maternal parenting stress, with a focus on structural and cultural explanations and variations by nativity and child age. In kindergarten, black mothers, albeit U.S.-born only, report more parenting stress than white mothers due to structural disadvantages and authoritarian parenting values. The black-white gap increases from kindergarten to third grade, and in third grade, U.S.-born black mothers' higher stress than white mothers' persists after controlling for structural and parenting factors. Hispanic and Asian mothers, albeit foreign-born only, report more stress than white mothers at both ages due to structural disadvantages and authoritarian values. Despite structural disadvantages, American Indian mothers report less stress.

Risk stratification using stress echocardiography: incremental prognostic value over historic, clinical, and stress electrocardiographic variables across a wide spectrum of bayesian pretest probabilities for coronary artery disease.

PubMed

Bangalore, Sripal; Gopinath, Devi; Yao, Siu-Sun; Chaudhry, Farooq A

2007-03-01

We sought to evaluate the risk stratification ability and incremental prognostic value of stress echocardiography over historic, clinical, and stress electrocardiographic (ECG) variables, over a wide spectrum of bayesian pretest probabilities of coronary artery disease (CAD). Stress echocardiography is an established technique for the diagnosis of CAD. However, data on incremental prognostic value of stress echocardiography over historic, clinical, and stress ECG variables in patients with known or suggested CAD is limited. We evaluated 3259 patients (60 +/- 13 years, 48% men) undergoing stress echocardiography. Patients were grouped into low (<15%), intermediate (15-85%), and high (>85%) pretest CAD likelihood subgroups using standard software. The historical, clinical, stress ECG, and stress echocardiographic variables were recorded for the entire cohort. Follow-up (2.7 +/- 1.1 years) for confirmed myocardial infarction (n = 66) and cardiac death (n = 105) was obtained. For the entire cohort, an ischemic stress echocardiography study confers a 5.0 times higher cardiac event rate than the normal stress echocardiography group (4.0% vs 0.8%/y, P < .0001). Furthermore, Cox proportional hazard regression model showed incremental prognostic value of stress echocardiography variables over historic, clinical, and stress ECG variables across all pretest probability subgroups (global chi2 increased from 5.1 to 8.5 to 20.1 in the low pretest group, P = .44 and P = .01; from 20.9 to 28.2 to 116 in the intermediate pretest group, P = .47 and P < .0001; and from 17.5 to 36.6 to 61.4 in the high pretest group, P < .0001 for both groups). A normal stress echocardiography portends a benign prognosis (<1% event rate/y) in all pretest probability subgroups and even in patients with high pretest probability and yields incremental prognostic value over historic, clinical, and stress ECG variables across all pretest probability subgroups. The best incremental value is, however, in the

Real time myocardial contrast echocardiography during supine bicycle stress and continuous infusion of contrast agent. Cutoff values for myocardial contrast replenishment discriminating abnormal myocardial perfusion.

PubMed

Miszalski-Jamka, Tomasz; Kuntz-Hehner, Stefanie; Schmidt, Harald; Hammerstingl, Christoph; Tiemann, Klaus; Ghanem, Alexander; Troatz, Clemens; Lüderitz, Berndt; Omran, Heyder

2007-07-01

Myocardial contrast echocardiography (MCE) is a new imaging modality for diagnosing coronary artery disease (CAD). The aim of our study was to evaluate feasibility of qualitative myocardial contrast replenishment (RP) assessment during supine bicycle stress MCE and find out cutoff values for such analysis, which could allow accurate detection of CAD. Forty-four consecutive patients, scheduled for coronary angiography (CA) underwent supine bicycle stress two-dimensional echocardiography (2DE). During the same session, MCE was performed at peak stress and post stress. Ultrasound contrast agent (SonoVue) was administered in continuous mode using an infusion pump (BR-INF 100, Bracco Research). Seventeen-segment model of left ventricle was used in analysis. MCE was assessed off-line in terms of myocardial contrast opacification and RP. RP was evaluated on the basis of the number of cardiac cycles required to refill the segment with contrast after its prior destruction with high-power frames. Determination of cutoff values for RP assessment was performed by means of reference intervals and receiver operating characteristic analysis. Quantitative CA was carried out using CAAS system. MCE could be assessed in 42 patients. CA revealed CAD in 25 patients. Calculated cutoff values for RP-analysis (peak-stress RP >3 cardiac cycles and difference between peak stress and post stress RP >0 cardiac cycles) provided sensitive (88%) and accurate (88%) detection of CAD. Sensitivity and accuracy of 2DE were 76% and 79%, respectively. Qualitative RP-analysis based on the number of cardiac cycles required to refill myocardium with contrast is feasible during supine bicycle stress MCE and enables accurate detection of CAD.

Self-perception and value system as possible predictors of stress.

PubMed

Sivberg, B

1998-03-01

This study was directed towards personality-related, value system and sociodemographic variables of nursing students in a situation of change, using a longitudinal perspective to measure their improvement in principle-based moral judgement (Kohlberg; Rest) as possible predictors of stress. Three subgroups of students were included from the commencement of the first three-year academic nursing programme in 1993. The students came from the colleges of health at Jönköping, Växjö and Kristianstad in the south of Sweden. A principal component factor analysis (varimax) was performed using data obtained from the students in the spring of 1994 (n = 122) and in the spring of 1996 (n = 112). There were 23 variables, of which two were sociodemographic, eight represented self-image, six were self-values, six were interpersonal values, and one was principle-based moral judgement. The analysis of data from students in the first year of a three-year programme demonstrated eight factors that explained 68.8% of the variance. The most important factors were: (1) ascendant decisive disorderly sociability and nonpractical mindedness (18.1% of the variance); (2) original vigour person-related trust (13.3%) of the variance); (3) orderly nonvigour achievement (8.9% of the variance) and (4) independent leadership (7.9% of the variance). (The term 'ascendancy' refers to self-confidence, and 'vigour' denotes responding well to challenges and coping with stress.) The analysis in 1996 demonstrated nine factors, of which the most important were: (1) ascendant original sociability with decisive nonconformist leadership (18.2% of the variance); (2) cautious person-related responsibility (12.6% of the variance); (3) orderly nonvariety achievement (8.4% of the variance); and (4) nonsupportive benevolent conformity (7.2% of the variance). A comparison of the two most prominent factors in 1994 and 1996 showed the process of change to be stronger for 18.2% and weaker for 30% of the variance

Spacecraft Maximum Allowable Concentrations for Airborne Contaminants

NASA Technical Reports Server (NTRS)

James, John T.

2008-01-01

The enclosed table lists official spacecraft maximum allowable concentrations (SMACs), which are guideline values set by the NASA/JSC Toxicology Group in cooperation with the National Research Council Committee on Toxicology (NRCCOT). These values should not be used for situations other than human space flight without careful consideration of the criteria used to set each value. The SMACs take into account a number of unique factors such as the effect of space-flight stress on human physiology, the uniform good health of the astronauts, and the absence of pregnant or very young individuals. Documentation of the values is given in a 5 volume series of books entitled "Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants" published by the National Academy Press, Washington, D.C. These books can be viewed electronically at http://books.nap.edu/openbook.php?record_id=9786&page=3. Short-term (1 and 24 hour) SMACs are set to manage accidental releases aboard a spacecraft and permit risk of minor, reversible effects such as mild mucosal irritation. In contrast, the long-term SMACs are set to fully protect healthy crewmembers from adverse effects resulting from continuous exposure to specific air pollutants for up to 1000 days. Crewmembers with allergies or unusual sensitivity to trace pollutants may not be afforded complete protection, even when long-term SMACs are not exceeded. Crewmember exposures involve a mixture of contaminants, each at a specific concentration (C(sub n)). These contaminants could interact to elicit symptoms of toxicity even though individual contaminants do not exceed their respective SMACs. The air quality is considered acceptable when the toxicity index (T(sub grp)) for each toxicological group of compounds is less than 1, where T(sub grp), is calculated as follows: T(sub grp) = C(sub 1)/SMAC(sub 1) + C(sub 2/SMAC(sub 2) + ...+C(sub n)/SMAC(sub n).

Health-Based Cyanotoxin Guideline Values Allow for Cyanotoxin-Based Monitoring and Efficient Public Health Response to Cyanobacterial Blooms

PubMed Central

Farrer, David; Counter, Marina; Hillwig, Rebecca; Cude, Curtis

2015-01-01

Human health risks from cyanobacterial blooms are primarily related to cyanotoxins that some cyanobacteria produce. Not all species of cyanobacteria can produce toxins. Those that do often do not produce toxins at levels harmful to human health. Monitoring programs that use identification of cyanobacteria genus and species and enumeration of cyanobacterial cells as a surrogate for cyanotoxin presence can overestimate risk and lead to unnecessary health advisories. In the absence of federal criteria for cyanotoxins in recreational water, the Oregon Health Authority (OHA) developed guideline values for the four most common cyanotoxins in Oregon’s fresh waters (anatoxin-a, cylindrospermopsin, microcystins, and saxitoxins). OHA developed three guideline values for each of the cyanotoxins found in Oregon. Each of the guideline values is for a specific use of cyanobacteria-affected water: drinking water, human recreational exposure and dog recreational exposure. Having cyanotoxin guidelines allows OHA to promote toxin-based monitoring (TBM) programs, which reduce the number of health advisories and focus advisories on times and places where actual, rather than potential, risks to health exist. TBM allows OHA to more efficiently protect public health while reducing burdens on local economies that depend on water recreation-related tourism. PMID:25664510

Value of stress ultrasound for the diagnosis of chronic ankle instability compared to manual anterior drawer test, stress radiography, magnetic resonance imaging, and arthroscopy.

PubMed

Cho, Jae Ho; Lee, Doo Hyung; Song, Hyung Keun; Bang, Joon Young; Lee, Kyung Tai; Park, Young Uk

2016-04-01

Clinicians frequently diagnose chronic ankle instability using the manual anterior drawer test and stress radiography. However, both examinations can yield incorrect results and do not reveal the extent of ankle instability. Stress ultrasound has been reported to be a new diagnostic tool for the diagnosis of chronic ankle instability. The purpose of this study was to assess the diagnostic value of stress ultrasound for chronic ankle instability compared to the manual anterior drawer test, stress radiography, magnetic resonance imaging (MRI), and arthroscopy. Twenty-eight consecutive patients who underwent ankle arthroscopy and subsequent modified Broström repair for treatment of chronic ankle instability were included. The arthroscopic findings were used as the reference standard. A standardized physical examination (manual anterior drawer test), stress radiography, MRI, and stress ultrasound were performed to assess the anterior talofibular ligament (ATFL) prior to operation. Ultrasound images were taken in the resting position and the maximal anterior drawer position. Grade 3 lateral instability was verified arthroscopically in all 28 cases with a clinical diagnosis (100%). Twenty-two cases showed grade III instability on the manual anterior drawer test (78.6%). Twenty-four cases displayed anterior translation exceeding 5 mm on stress radiography (86%), and talar tilt angle exceeded 15° in three cases (11 %). Nineteen cases displayed a partial chronic tear (change in thickness or signal intensity), and nine cases displayed complete tear on MRI (100%). Lax and wavy ATFL was evident on stress ultrasound in all cases (100 %). The mean value of the ATFL length was 2.8 ± 0.3 cm for the stressed condition and 2.1 ± 0.2 cm for the resting condition (p < 0.001). Stress ultrasound may be useful for the diagnosis of chronic ankle instability in addition to the manual anterior drawer test and stress radiography. III.

15 CFR 921.81 - Allowable costs.

Code of Federal Regulations, 2010 CFR

2010-01-01

... ESTUARINE RESEARCH RESERVE SYSTEM REGULATIONS General Financial Assistance Provisions § 921.81 Allowable..., the fair market value of real property allowable as match is limited to the fair market value of a real property interest equivalent to, or required to attain, the level of control over such land(s...

Integral flange design program. [procedure for computing stresses

NASA Technical Reports Server (NTRS)

Wilson, J. F.

1974-01-01

An automated interactive flange design program utilizing an electronic desk top calculator is presented. The program calculates the operating and seating stresses for circular flanges of the integral or optional type subjected to internal pressure. The required input information is documented. The program provides an automated procedure for computing stresses in selected flange geometries for comparison to the allowable code values.

76 FR 32340 - Federal Travel Regulation; Temporary Duty (TDY) Travel Allowances (Taxes); Relocation Allowances...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-06

..., as taxable income. When you receive taxable benefits, you must pay income tax on the amount or value... Allowances (Taxes); Relocation Allowances (Taxes) AGENCY: Office of Governmentwide Policy (OGP), General...) concerning calculation of reimbursements for taxes on relocation expenses. In addition, this proposed rule...

Morphology of residually stressed tubular tissues: Beyond the elastic multiplicative decomposition

NASA Astrophysics Data System (ADS)

Ciarletta, P.; Destrade, M.; Gower, A. L.; Taffetani, M.

2016-05-01

Many interesting shapes appearing in the biological world are formed by the onset of mechanical instability. In this work we consider how the build-up of residual stress can cause a solid to buckle. In all past studies a fictitious (virtual) stress-free state was required to calculate the residual stress. In contrast, we use a model which is simple and allows the prescription of any residual stress field. We specialize the analysis to an elastic tube subject to a two-dimensional residual stress, and find that incremental wrinkles can appear on its inner or its outer face, depending on the location of the highest value of the residual hoop stress. We further validate the predictions of the incremental theory with finite element simulations, which allow us to go beyond this threshold and predict the shape, number and amplitude of the resulting creases.

The Impact of Racial Identity, Ethnic Identity, Asian Values and Race-Related Stress on Asian Americans and Asian International College Students’ Psychological Well-Being

PubMed Central

Iwamoto, Derek Kenji; Liu, William Ming

2010-01-01

The current study investigated the direct and moderating effects of racial identity, ethnic identity, Asian values, and race-related stress on positive psychological well-being among 402 Asian American and Asian international college students. Results revealed that the racial identity statuses Internalization, Immersion-Emersion, Dissonance, Asian values and Ethnic Identity Affirmation and Belonging were significant predictors of well-being. Asian values, Dissonance and Conformity were found to moderate the relationship between race-related stress on well-being. Specifically, individuals in low race-related stress conditions who had low Asian values, high Conformity and low Dissonance attitudes started high on well being but decreased as race-related stress increased. These findings underscore the importance of how racial identity statuses, Asian values and ethnic identity jointly and uniquely explain and moderate the effects of race-related stress on positive well-being. Implications for future research and clinical practice are discussed. PMID:20396592

The impact of racial identity, ethnic identity, asian values and race-related stress on Asian Americans and Asian international college students' psychological well-being.

PubMed

Iwamoto, Derek Kenji; Liu, William Ming

2010-01-01

The current study investigated the direct and moderating effects of racial identity, ethnic identity, Asian values, and race-related stress on positive psychological well-being among 402 Asian American and Asian international college students. Results revealed that the racial identity statuses Internalization, Immersion-Emersion, Dissonance, Asian values and Ethnic Identity Affirmation and Belonging were significant predictors of well-being. Asian values, Dissonance and Conformity were found to moderate the relationship between race-related stress on well-being. Specifically, individuals in low race-related stress conditions who had low Asian values, high Conformity and low Dissonance attitudes started high on well being but decreased as race-related stress increased. These findings underscore the importance of how racial identity statuses, Asian values and ethnic identity jointly and uniquely explain and moderate the effects of race-related stress on positive well-being. Implications for future research and clinical practice are discussed.

Adaptive Value of Phenological Traits in Stressful Environments: Predictions Based on Seed Production and Laboratory Natural Selection

PubMed Central

Glorieux, Cédric; Cuguen, Joel; Roux, Fabrice

2012-01-01

Phenological traits often show variation within and among natural populations of annual plants. Nevertheless, the adaptive value of post-anthesis traits is seldom tested. In this study, we estimated the adaptive values of pre- and post-anthesis traits in two stressful environments (water stress and interspecific competition), using the selfing annual species Arabidopsis thaliana. By estimating seed production and by performing laboratory natural selection (LNS), we assessed the strength and nature (directional, disruptive and stabilizing) of selection acting on phenological traits in A. thaliana under the two tested stress conditions, each with four intensities. Both the type of stress and its intensity affected the strength and nature of selection, as did genetic constraints among phenological traits. Under water stress, both experimental approaches demonstrated directional selection for a shorter life cycle, although bolting time imposes a genetic constraint on the length of the interval between bolting and anthesis. Under interspecific competition, results from the two experimental approaches showed discrepancies. Estimation of seed production predicted directional selection toward early pre-anthesis traits and long post-anthesis periods. In contrast, the LNS approach suggested neutrality for all phenological traits. This study opens questions on adaptation in complex natural environment where many selective pressures act simultaneously. PMID:22403624

30 CFR 206.460 - Transportation allowances-general.

Code of Federal Regulations, 2010 CFR

2010-07-01

... washing allowance and the transportation allowance reduce the value for royalty purposes to zero. (c)(1... quantity of clean coal output and the rejected waste material. The transportation allowance shall be...

High-resolution stress measurements for microsystem and semiconductor applications

NASA Astrophysics Data System (ADS)

Vogel, Dietmar; Keller, Juergen; Michel, Bernd

2006-04-01

Research results obtained for local stress determination on micro and nanotechnology components are summarized. It meets the concern of controlling stresses introduced to sensors, MEMS and electronics devices during different micromachining processes. The method bases on deformation measurement options made available inside focused ion beam equipment. Removing locally material by ion beam milling existing stresses / residual stresses lead to deformation fields around the milled feature. Digital image correlation techniques are used to extract deformation values from micrographs captured before and after milling. In the paper, two main milling features have been analyzed - through hole and through slit milling. Analytical solutions for stress release fields of in-plane stresses have been derived and compared to respective experimental findings. Their good agreement allows to settle a method for determination of residual stress values, which is demonstrated for thin membranes manufactured by silicon micro technology. Some emphasis is made on the elimination of main error sources for stress determination, like rigid body object displacements and rotations due to drifts of experimental conditions under FIB imaging. In order to illustrate potential application areas of the method residual stress suppression by ion implantation is evaluated by the method and reported here.

FIB-based measurement of local residual stresses on microsystems

NASA Astrophysics Data System (ADS)

Vogel, Dietmar; Sabate, Neus; Gollhardt, Astrid; Keller, Juergen; Auersperg, Juergen; Michel, Bernd

2006-03-01

The paper comprises research results obtained for stress determination on micro and nanotechnology components. It meets the concern of controlling stresses introduced to sensors, MEMS and electronics devices during different micromachining processes. The method bases on deformation measurement options made available inside focused ion beam equipment. Removing locally material by ion beam milling existing stresses / residual stresses lead to deformation fields around the milled feature. Digital image correlation techniques are used to extract deformation values from micrographs captured before and after milling. In the paper, two main milling features have been analyzed - through hole and through slit milling. Analytical solutions for stress release fields of in-plane stresses have been derived and compared to respective experimental findings. Their good agreement allows to settle a method for determination of residual stress values, which is demonstrated for thin membranes manufactured by silicon micro technology. Some emphasis is made on the elimination of main error sources for stress determination, like rigid body object displacements and rotations due to drifts of experimental conditions under FIB imaging. In order to illustrate potential application areas of the method residual stress suppression by ion implantation is evaluated by the method and reported here.

Allowance market pricing indicators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, R.W.

1995-12-31

Regardless of whether buyers and sellers rely on one allowance price indicator or a combination of several, the publication of price indicators has facilitated trading in the SO{sub 2} allowance market. Buyers and sellers feel more comfortable with a price benchmark against which to measure their actions; liquidity has increased; and transactions are easier to conclude. At this market`s present stage of development, five price indicators are worthy of discussion: EPA Allowance Auctions; Compliance Strategies Review`s EATX; Utility Environment Report`s price range; Cantor Fitzgerald`s Allowance Price Indicators; and Emissions Exchange Corporation`s Exchange Values. But experience in other markets indicates thatmore » (1) others will be created as the market develops, and (2) all published price indicators will tend to converge as time passes.« less

Regional variation of stress level in the Himalayas after the 25 April 2015 Gorkha earthquake (Nepal) estimated using b-values

NASA Astrophysics Data System (ADS)

Ramesh, Pudi; Martha, Tapas R.; Vinod Kumar, K.

2018-06-01

The Gutenberg-Richter (G-R) relation and its parameters reflect the distribution of magnitude and frequency of earthquakes in a seismically active region. Different segments of the Himalayas from west to east behave differently in their G-R relation. In this study, b-values from the G-R relation were computed for the four different seismic zones of the Himalayas, in order to understand the regional variation of stress levels. It was found that the b-value of the Eastern zone is relatively lower than that of the other zones. The b-values before and after the Gorkha (25 April 2015) and Dolakha (12 May 2015) earthquakes were compared for the Central-II seismic zone, where the epicentres of both earthquakes were located. It was observed that the b-value has increased gradually in this region since stress was released episodically. It was also observed that b-values in adjacent zones are lower than that in the source region of the 25 April 2015 earthquake, implying high-stress accumulation. This indicates that the recurrence period of a large earthquake will be high in adjacent zones, particularly in the Eastern zone.

Supplementation of vitamin E, selenium and increased energy allowance mitigates the transition stress and improves postpartum reproductive performance in the crossbred cow.

PubMed

Khatti, Amit; Mehrotra, Sanjeev; Patel, Pankaj Kumar; Singh, Gyanendra; Maurya, Vijai Prakash; Mahla, Ajit Singh; Chaudhari, Ravjibhai Karshanbhai; Das, Gautam Kumar; Singh, Mithilesh; Sarkar, Mihir; Kumar, Harendra; Krishnaswamy, Narayanan

2017-12-01

Dairy cow undergoes tremendous physiological challenges during the transition period leading to negative energy balance (NEBAL), impaired immunity and oxidative stress that ultimately compromises the postpartum fertility. Accordingly, we investigated the effects of antioxidant supplementation and increased energy allowance on transition stress and fertility of crossbred cow. Advanced pregnant crossbred cows (n = 26) of 2-4 parity and lactation potential of >10 L/day were divided into two equal groups (n = 13 cows/group). Cows were fed diets either (i) supplemented with vitamin E (80 IU/kg DM), Selenium (Se; 0.3 mg/kg DM) and increased energy allowance in the form of 20% additional concentrate (TRT) or (ii) basal diet without any supplementation as control (CON). Vitamin E and Se were supplemented with wheat flour bolus from -4 to 8 week of calving whereas energy allowance was increased from 2 to 8 week of calving on daily basis to individual animal (where 0 is day of calving). Blood samples were collected on weekly interval from -4 to 8 week of calving. Oxidative stress was assessed by estimation of malondialdehyde (MDA), total antioxidant capacity (TAC), superoxide dismutase (SOD) and catalase (CAT). Immunity level was assessed via estimation of phagocytic activity (PA) of granulocytes and lymphocyte proliferation assay (LPA). Postpartum fertility was assessed by interval to first postpartum estrus (day) and pregnancy rate. Cows in TRT had a significantly lower MDA, higher TAC and decreased activity of SOD and CAT than that of CON (P < 0.05). Phagocytic activity increased at -1, 0 and 3-8 weeks postpartum (P < 0.05) while LPA showed difference (P < 0.05) at parturition, week 4 and 8 postpartum. Marked improvement in the fertility was recorded in terms of early resumption of postpartum estrus (P < 0.001) and higher pregnancy rate (P < 0.05). Copyright © 2017 Elsevier Inc. All rights reserved.

Low-Grade Inflammation and Ambulatory Cortisol in Adolescents: Interaction Between Interviewer-Rated Versus Self-Rated Acute Stress and Chronic Stress.

PubMed

Schreier, Hannah M C; Chen, Edith

To determine whether the association between self-rated or interviewer-rated recent acute stress exposures and low-grade inflammation and daily cortisol production in adolescents is moderated by chronic stress ratings. Acute and chronic stress exposures were assessed in 261 adolescents aged 13 to 16 years using a semistructured life stress interview. The negative impact of acute stressors was independently rated by both adolescents (self-rated) and interviewers (interviewer-rated). Markers of inflammation (interleukin (IL)-6, IL-1ra, C-reactive protein) were measured from peripheral blood samples obtained via antecubital venipuncture. Participants collected 4 saliva samples at home on each of 6 consecutive days for the analysis of diurnal salivary cortisol profiles. There were no main effects of acute stressors (self- and interviewer-rated) and chronic family or peer stress on adolescent inflammation markers and cortisol (p values > .10). However, the interaction between interviewer-rated acute stress and chronic family stress was significantly associated with adolescent inflammation markers (IL-6, IL-1ra). Specifically, as chronic family stress increased, the association between acute stressor impact (interviewer-rated) and inflammation markers became more positive (IL-6 (B = .054, SE = .023, p = .022); IL-1ra (B = .030, SE = .014, p = .034)). Interactions between self-rated acute stress and chronic family stress were not associated with any biological measures (p values > .10). Interactions between acute stressor impact (both self- and interviewer-rated) and chronic peer stress were also not significantly associated with any biological measures (p values > .05). Among adolescents, interviewer-based ratings of acute stressor impact may allow for better prediction of health-relevant inflammation markers than adolescents' own ratings.

Effect of the Yield Stress and r-value Distribution on the Earing Profile of Cup Drawing with Yld2000-2d Yield Function

NASA Astrophysics Data System (ADS)

Lou, Yanshan; Bae, Gihyun; Lee, Changsoo; Huh, Hoon

2010-06-01

This paper deals with the effect of the yield stress and r-value distribution on the earing in the cup drawing. The anisotropic yield function, Yld2000-2d yield function, is selected to describe the anisotropy of two metal sheets, 719B and AA5182-O. The tool dimension is referred from the Benchmark problem of NUMISHEET'2002. The Downhill Simplex method is applied to identify the anisotropic coefficients in Yld2000-2d yield function. Simulations of the drawing process are performed to investigate the earing profile of two materials. The earing profiles obtained from simulations are compared with the analytical model developed by Hosford and Caddell. Simulations are conducted with respect to the change of the yield stress and r-value distribution, respectively. The correlation between the anisotropy and the earing tendency is investigated based on simulation data. Finally, the earing mechanism is analyzed through the deformation process of the blank during the cup deep drawing. It can be concluded that ears locate at angular positions with lower yield stress and higher r-value while the valleys appear at the angular position with higher yield stress and lower r-value. The effect of the yield stress distribution is more important for the cup height distribution than that of the r-value distribution.

Work stress, Chinese work values, and work well-being in the Greater China.

PubMed

Lu, Luo; Kao, Shu-Fang; Siu, Oi-Ling; Lu, Chang-Qin

2011-01-01

Work values influence our attitudes and behavior at work, but they have rarely been explored in the context of work stress. The aim of this research was thus to test direct and moderating effects of Chinese work values (CWV) on relationships between work stressors and work well-being among employees in the Greater China region. A self-administered survey was conducted to collect data from three major cities in the region, namely Beijing, Hong Kong, and Taipei (N = 380). Work stressors were negatively related to work well-being, whereas CWV were positively related to work well-being. In addition, CWV also demonstrated moderating effects in some of the stressor-job satisfaction relationships.

Molt-associated changes in hematologic and plasma biochemical values and stress hormone levels in African penguins (Spheniscus demersus).

PubMed

Mazzaro, Lisa M; Meegan, Jenny; Sarran, Delphine; Romano, Tracy A; Bonato, Vinicius; Deng, Shibing; Dunn, J Lawrence

2013-12-01

Handling, including blood collection, has often been discouraged in molting penguins because it is considered an additional stress imposed on birds already experiencing major physiologic stress associated with molting. To evaluate the degree of physiologic stress posed by molting, we compared the hematologic and plasma biochemical values and hormone levels of molting and nonmolting African penguins, Spheniscus demersus. Five male and 5 female penguins randomly chosen were given complete physical examinations, were weighed, and blood samples were taken at 7 time points before, during, and after the molt. Data were analyzed by linear mixed-model analysis of variance. Throughout the study, behavior and appetite remained normal. Catecholamine levels were highly variable within and among subjects, whereas mean corticosterone levels were significantly different between baseline, molt, and postmolt values. Significant differences from baseline values were observed in many of the hematologic analytes; however, only decreases in hematocrit and red blood cell count values were considered clinically significant. Anemia due to experimentally induced blood loss as a possible cause of the significant hematologic changes was ruled out based on results of a follow-up control study during the nonmolt season, which showed no significant changes in hematocrit level or total red blood cell counts when using similar sampling protocols, which indicates that these changes were associated with molt.

Review of family relational stress and pediatric asthma: the value of biopsychosocial systemic models.

PubMed

Wood, Beatrice L; Miller, Bruce D; Lehman, Heather K

2015-06-01

Asthma is the most common chronic disease in children. Despite dramatic advances in pharmacological treatments, asthma remains a leading public health problem, especially in socially disadvantaged minority populations. Some experts believe that this health gap is due to the failure to address the impact of stress on the disease. Asthma is a complex disease that is influenced by multilevel factors, but the nature of these factors and their interrelations are not well understood. This paper aims to integrate social, psychological, and biological literatures on relations between family/parental stress and pediatric asthma, and to illustrate the utility of multilevel systemic models for guiding treatment and stimulating future research. We used electronic database searches and conducted an integrated analysis of selected epidemiological, longitudinal, and empirical studies. Evidence is substantial for the effects of family/parental stress on asthma mediated by both disease management and psychobiological stress pathways. However, integrative models containing specific pathways are scarce. We present two multilevel models, with supporting data, as potential prototypes for other such models. We conclude that these multilevel systems models may be of substantial heuristic value in organizing investigations of, and clinical approaches to, the complex social-biological aspects of family stress in pediatric asthma. However, additional systemic models are needed, and the models presented herein could serve as prototypes for model development. © 2015 Family Process Institute.

Does Confucianism allow for body donation?

PubMed

Jones, D Gareth; Nie, Jing-Bao

2018-01-16

Confucianism has been widely perceived as a major moral and cultural obstacle to the donation of bodies for anatomical purposes. The rationale for this is the Confucian stress on xiao (filial piety), whereby individuals' bodies are to be intact at death. In the view of many, the result is a prohibition on the donation of bodies to anatomy departments for the purpose of dissection. The role of dissection throughout the development of anatomy within a Confucian context is traced, and in contemporary China the establishment of donation programs and the appearance of memorial monuments is noted. In reassessing Confucian attitudes, the stress laid on a particular interpretation of filial piety is questioned, and an attempt is made to balance this with the Confucian emphasis on a moral duty to those outside one's immediate family. The authors argue that the fundamental Confucian norm ren (humaneness or benevolence) allows for body donation as people have a moral duty to help others. Moreover, the other central Confucian value, li (rites), offers important insights on how body donation should be performed as a communal activity, particularly the necessity of developing ethically and culturally appropriate rituals for body donation. In seeking to learn from this from a Western perspective, it is contended that in all societies the voluntary donation of bodies is a deeply human activity that is to reflect the characteristics of the community within which it takes place. This is in large part because it has educational and personal repercussions for students. Anat Sci Educ. © 2018 American Association of Anatomists. © 2018 American Association of Anatomists.

Prognostic Value of Quantitative Stress Perfusion Cardiac Magnetic Resonance.

PubMed

Sammut, Eva C; Villa, Adriana D M; Di Giovine, Gabriella; Dancy, Luke; Bosio, Filippo; Gibbs, Thomas; Jeyabraba, Swarna; Schwenke, Susanne; Williams, Steven E; Marber, Michael; Alfakih, Khaled; Ismail, Tevfik F; Razavi, Reza; Chiribiri, Amedeo

2018-05-01

This study sought to evaluate the prognostic usefulness of visual and quantitative perfusion cardiac magnetic resonance (CMR) ischemic burden in an unselected group of patients and to assess the validity of consensus-based ischemic burden thresholds extrapolated from nuclear studies. There are limited data on the prognostic value of assessing myocardial ischemic burden by CMR, and there are none using quantitative perfusion analysis. Patients with suspected coronary artery disease referred for adenosine-stress perfusion CMR were included (n = 395; 70% male; age 58 ± 13 years). The primary endpoint was a composite of cardiovascular death, nonfatal myocardial infarction, aborted sudden death, and revascularization after 90 days. Perfusion scans were assessed visually and with quantitative analysis. Cross-validated Cox regression analysis and net reclassification improvement were used to assess the incremental prognostic value of visual or quantitative perfusion analysis over a baseline clinical model, initially as continuous covariates, then using accepted thresholds of ≥2 segments or ≥10% myocardium. After a median 460 days (interquartile range: 190 to 869 days) follow-up, 52 patients reached the primary endpoint. At 2 years, the addition of ischemic burden was found to increase prognostic value over a baseline model of age, sex, and late gadolinium enhancement (baseline model area under the curve [AUC]: 0.75; visual AUC: 0.84; quantitative AUC: 0.85). Dichotomized quantitative ischemic burden performed better than visual assessment (net reclassification improvement 0.043 vs. 0.003 against baseline model). This study was the first to address the prognostic benefit of quantitative analysis of perfusion CMR and to support the use of consensus-based ischemic burden thresholds by perfusion CMR for prognostic evaluation of patients with suspected coronary artery disease. Quantitative analysis provided incremental prognostic value to visual assessment and

Profiling nurses' job satisfaction, acculturation, work environment, stress, cultural values and coping abilities: A cluster analysis.

PubMed

Goh, Yong-Shian; Lee, Alice; Chan, Sally Wai-Chi; Chan, Moon Fai

2015-08-01

This study aimed to determine whether definable profiles existed in a cohort of nursing staff with regard to demographic characteristics, job satisfaction, acculturation, work environment, stress, cultural values and coping abilities. A survey was conducted in one hospital in Singapore from June to July 2012, and 814 full-time staff nurses completed a self-report questionnaire (89% response rate). Demographic characteristics, job satisfaction, acculturation, work environment, perceived stress, cultural values, ways of coping and intention to leave current workplace were assessed as outcomes. The two-step cluster analysis revealed three clusters. Nurses in cluster 1 (n = 222) had lower acculturation scores than nurses in cluster 3. Cluster 2 (n = 362) was a group of younger nurses who reported higher intention to leave (22.4%), stress level and job dissatisfaction than the other two clusters. Nurses in cluster 3 (n = 230) were mostly Singaporean and reported the lowest intention to leave (13.0%). Resources should be allocated to specifically address the needs of younger nurses and hopefully retain them in the profession. Management should focus their retention strategies on junior nurses and provide a work environment that helps to strengthen their intention to remain in nursing by increasing their job satisfaction. © 2014 Wiley Publishing Asia Pty Ltd.

Most oxidative stress response in water samples comes from unknown chemicals: the need for effect-based water quality trigger values.

PubMed

Escher, Beate I; van Daele, Charlotte; Dutt, Mriga; Tang, Janet Y M; Altenburger, Rolf

2013-07-02

The induction of adaptive stress response pathways is an early and sensitive indicator of the presence of chemical and non-chemical stressors in cells. An important stress response is the Nrf-2 mediated oxidative stress response pathway where electrophilic chemicals or chemicals that cause the formation of reactive oxygen species initiate the production of antioxidants and metabolic detoxification enzymes. The AREc32 cell line is sensitive to chemicals inducing oxidative stress and has been previously applied for water quality monitoring of organic micropollutants and disinfection byproducts. Here we propose an algorithm for the derivation of effect-based water quality trigger values for this end point that is based on the combined effects of mixtures of regulated chemicals. Mixture experiments agreed with predictions by the mixture toxicity concept of concentration addition. The responses in the AREc32 and the concentrations of 269 individual chemicals were quantified in nine environmental samples, ranging from treated effluent, recycled water, stormwater to drinking water. The effects of the detected chemicals could explain less than 0.1% of the observed induction of the oxidative stress response in the sample, affirming the need to use effect-based trigger values that account for all chemicals present.

14 CFR 1261.109 - Computation of allowance.

Code of Federal Regulations, 2010 CFR

2010-01-01

... exchange). There will be no allowance for replacement cost or for appreciation in the value of the property...) Depreciation in value is determined by considering the type of article involved, its cost, its condition when...

30 CFR 1206.457 - Washing allowances-general.

Code of Federal Regulations, 2011 CFR

2011-07-01

... wash coal, unless the value determined pursuant to § 1206.456 of this subpart was based upon like... allowance reduce the value for royalty purposes to zero. (b) If ONRR determines that a lessee has improperly...

30 CFR 1206.258 - Washing allowances-general.

Code of Federal Regulations, 2011 CFR

2011-07-01

... wash coal, unless the value determined pursuant to § 1206.257 of this subpart was based upon like... allowance reduce the value for royalty purposes to zero. (b) If ONRR determines that a lessee has improperly...

Mechanism of laser-induced stress relaxation in cartilage

NASA Astrophysics Data System (ADS)

Sobol, Emil N.; Sviridov, Alexander P.; Omelchenko, Alexander I.; Bagratashvili, Victor N.; Bagratashvili, Nodar V.; Popov, Vladimir K.

1997-06-01

The paper presents theoretical and experimental results allowing to discuss and understand the mechanism of stress relaxation and reshaping of cartilage under laser radiation. A carbon dioxide and a Holmium laser was used for treatment of rabbits and human cartilage. We measured temperature, stress, amplitude of oscillation by free and forced vibration, internal friction, and light scattering in the course of laser irradiation. Using experimental data and theoretical modeling of heat and mass transfer in cartilaginous tissue we estimated the values of transformation heat, diffusion coefficients and energy activation for water movement.

14 CFR 1261.109 - Computation of allowance.

Code of Federal Regulations, 2011 CFR

2011-01-01

... to the loss or damage of property lost or damaged beyond economical repair, less any salvage value... price paid in cash or property, or the value at the time of acquisition if not acquired by purchase or exchange). There will be no allowance for replacement cost or for appreciation in the value of the property...

Thermal stresses investigation of a gas turbine blade

NASA Astrophysics Data System (ADS)

Gowreesh, S.; Pravin, V. K.; Rajagopal, K.; Veena, P. H.

2012-06-01

The analysis of structural and thermal stress values that are produced while the turbine is operating are the key factors of study while designing the next generation gas turbines. The present study examines structural, thermal, modal analysis of the first stage rotor blade of a two stage gas turbine. The design features of the turbine segment of the gas turbine have been taken from the preliminary design of a power turbine for maximization of an existing turbojet engine with optimized dump gap of the combustion chamber, since the allowable temperature on the turbine blade dependents on the hot gas temperatures from the combustion chamber. In the present paper simplified 3-D Finite Element models are developed with governing boundary conditions and solved using the commercial FEA software ANSYS. As the temperature has a significant effect on the overall stress on the rotor blades, a detail study on mechanical and thermal stresses are estimated and evaluated with the experimental values.

Student Achievement in Undergraduate Statistics: The Potential Value of Allowing Failure

ERIC Educational Resources Information Center

Ferrandino, Joseph A.

2016-01-01

This article details what resulted when I re-designed my undergraduate statistics course to allow failure as a learning strategy and focused on achievement rather than performance. A variety of within and between sample t-tests are utilized to determine the impact of unlimited test and quiz opportunities on student learning on both quizzes and…

Strain-encoded cardiac MRI as an adjunct for dobutamine stress testing: incremental value to conventional wall motion analysis.

PubMed

Korosoglou, Grigorios; Lossnitzer, Dirk; Schellberg, Dieter; Lewien, Antje; Wochele, Angela; Schaeufele, Tim; Neizel, Mirja; Steen, Henning; Giannitsis, Evangelos; Katus, Hugo A; Osman, Nael F

2009-03-01

High-dose dobutamine stress MRI is safe and feasible for the diagnosis of coronary artery disease (CAD) in humans. However, the assessment of cine scans relies on the visual interpretation of regional wall motion, which is subjective. Recently, strain-encoded MRI (SENC) has been proposed for the direct color-coded visualization of myocardial strain. The purpose of our study was to compare the diagnostic value of SENC with that provided by conventional wall motion analysis for the detection of inducible ischemia during dobutamine stress MRI. Stress-induced ischemia was assessed by wall motion analysis and by SENC in 101 patients with suspected or known CAD and in 17 healthy volunteers who underwent dobutamine stress MRI in a clinical 1.5-T scanner. Quantitative coronary angiography deemed as the standard reference for the presence or absence of significant CAD (> or =50% diameter stenosis). On a coronary vessel level, SENC detected inducible ischemia in 86 of 101 versus 71 of 101 diseased coronary vessels (P<0.01 versus cine) and showed normal strain response in 189 of 202 versus 194 of 202 vessels with <50% stenosis (P=NS versus cine). On a patient level, SENC detected inducible ischemia in 63 of 64 versus 55 of 64 patients with CAD (P<0.05 versus cine) and showed normal strain response in 32 of 37 versus 34 of 37 patients without CAD (P=NS versus cine). Quantification analysis demonstrated a significant correlation between strain rate reserve and coronary artery stenosis severity (r(2)=0.56, P<0.001), and a cutoff value of strain rate reserve of 1.64 was deemed as a highly accurate marker for the detection of > or =50% stenosis (area under the curve, 0.96; SE, 0.01; 95% CI, 0.94 to 0.98; P<0.001). The direct color-coded visualization of strain on MR images is a useful adjunct for dobutamine stress MRI, which provides incremental value for the detection of CAD compared with conventional wall motion readings on cine images.

Interface stresses in fiber-reinforced materials with regular fiber arrangements

NASA Astrophysics Data System (ADS)

Mueller, W. H.; Schmauder, S.

The theory of linear elasticity is used here to analyze the stresses inside and at the surface of fiber-reinforced composites. Plane strain, plane stress, and generalized plane strain are analyzed using the shell model and the BHE model and are numerically studied using finite element analysis. Interface stresses are shown to depend weakly on Poisson's ratio. For equal values of the ratio, generalized plane strain and plane strain results are identical. For small volume fractions up to 40 vol pct of fibers, the shell and the BHE models predict the interface stresses very well over a wide range of elastic mismatches and for different fiber arrangements. At higher volume fractions the stresses are influenced by interactions with neighboring fibers. Introducing an external pressure into the shell model allows the prediction of interface stresses in real composite with isolated or regularly arranged fibers.

19 CFR 148.103 - Family grouping of allowances.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 19 Customs Duties 2 2011-04-01 2011-04-01 false Family grouping of allowances. 148.103 Section 148... Value § 148.103 Family grouping of allowances. (a) Generally. When members of a family residing in one... grouped and allowed without regard to which member of the family is the owner of the articles. A group...

19 CFR 148.103 - Family grouping of allowances.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 19 Customs Duties 2 2012-04-01 2012-04-01 false Family grouping of allowances. 148.103 Section 148... Value § 148.103 Family grouping of allowances. (a) Generally. When members of a family residing in one... grouped and allowed without regard to which member of the family is the owner of the articles. A group...

19 CFR 148.103 - Family grouping of allowances.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 19 Customs Duties 2 2013-04-01 2013-04-01 false Family grouping of allowances. 148.103 Section 148... Value § 148.103 Family grouping of allowances. (a) Generally. When members of a family residing in one... grouped and allowed without regard to which member of the family is the owner of the articles. A group...

19 CFR 148.103 - Family grouping of allowances.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 19 Customs Duties 2 2014-04-01 2014-04-01 false Family grouping of allowances. 148.103 Section 148... Value § 148.103 Family grouping of allowances. (a) Generally. When members of a family residing in one... grouped and allowed without regard to which member of the family is the owner of the articles. A group...

Real-time myocardial perfusion imaging for pharmacologic stress testing: added value to single photon emission computed tomography.

PubMed

Korosoglou, Grigorios; Dubart, Alain-Eric; DaSilva, K Gaspar C; Labadze, Nino; Hardt, Stefan; Hansen, Alexander; Bekeredjian, Raffi; Zugck, Christian; Zehelein, Joerg; Katus, Hugo A; Kuecherer, Helmut

2006-01-01

Little is known about the incremental value of real-time myocardial contrast echocardiography (MCE) as an adjunct to pharmacologic stress testing. This study was performed to evaluate the diagnostic value of MCE to detect abnormal myocardial perfusion by technetium Tc 99m sestamibi-single photon emission computed tomography (SPECT) and anatomically significant coronary artery disease (CAD) by angiography. Myocardial contrast echocardiography was performed at rest and during vasodilator stress in consecutive patients (N = 120) undergoing SPECT imaging for known or suspected CAD. Myocardial opacification, wall motion, and tracer uptake were visually analyzed in 12 myocardial segments by 2 pairs of blinded observers. Concordance between the 2 methods was assessed using the kappa statistic. Of 1356 segments, 1025 (76%) were interpretable by MCE, wall motion, and SPECT. Sensitivity of wall motion was 75%, specificity 83%, and accuracy 81% for detecting abnormal myocardial perfusion by SPECT (kappa = 0.53). Myocardial contrast echocardiography and wall motion together yielded significantly higher sensitivity (85% vs 74%, P < .05), specificity of 83%, and accuracy of 85% (kappa = 0.64) for the detection of abnormal myocardial perfusion. In 89 patients who underwent coronary angiography, MCE and wall motion together yielded higher sensitivity (83% vs 64%, P < .05) and accuracy (77% vs 68%, P < .05) but similar specificity (72%) compared with SPECT for the detection of high-grade, stenotic (> or = 75%) coronary lesions. Assessment of myocardial perfusion adds value to conventional stress echocardiography by increasing its sensitivity for the detection of functionally abnormal myocardial perfusion. Myocardial contrast echocardiography and wall motion together provide higher sensitivity and accuracy for detection of CAD compared with SPECT.

Shared Values, Particular Values, and Education for a Multicultural Society.

ERIC Educational Resources Information Center

Singh, Basil R.

1995-01-01

Within the framework of liberal democratic values are shared (universal) values and particular cultural values. Social harmony depends on integrating these two sets of values. The role of multicultural education is to stress cultural development rather than cultural maintenance while adhering to principles of inclusion. (SK)

49 CFR 192.620 - Alternative maximum allowable operating pressure for certain steel pipelines.

Code of Federal Regulations, 2011 CFR

2011-10-01

... of a maximum allowable operating pressure based on higher stress levels in the following areas: Take... pipeline at the increased stress level under this section with conventional operation; and (ii) Describe... targeted audience; and (B) Include information about the integrity management activities performed under...

49 CFR 192.620 - Alternative maximum allowable operating pressure for certain steel pipelines.

Code of Federal Regulations, 2013 CFR

2013-10-01

... of a maximum allowable operating pressure based on higher stress levels in the following areas: Take... pipeline at the increased stress level under this section with conventional operation; and (ii) Describe... targeted audience; and (B) Include information about the integrity management activities performed under...

49 CFR 192.620 - Alternative maximum allowable operating pressure for certain steel pipelines.

Code of Federal Regulations, 2012 CFR

2012-10-01

... of a maximum allowable operating pressure based on higher stress levels in the following areas: Take... pipeline at the increased stress level under this section with conventional operation; and (ii) Describe... targeted audience; and (B) Include information about the integrity management activities performed under...

Mapping b-value for 2009 Harrat Lunayyir earthquake swarm, western Saudi Arabia and Coulomb stress for its mainshock

NASA Astrophysics Data System (ADS)

Abdelfattah, Ali K.; Mogren, Saad; Mukhopadhyay, Manoj

2017-01-01

The Harrat Lunayyir (HL) earthquake swarm of 2009 originated in the HL volcanic field and attracted global attention mainly due to three factors: (i) its relatively short life span that ushered a large frequency of the swarm population (30,000 events in < 2 years), (ii) the swarm epicenter zone was contained within a small crustal volume under the HL and (iii) the migratory nature of the swarm following the tectonic trend of a normal fault zone beneath HL. The HL belongs to the Large Igneous Province of Saudi Arabia (LIP-SA) where it correlates to the Great Dikes locally. Our aim in this study is to describe the spatial distribution of the hypocenters, b-value character, and Coulomb stress failure (CSF) in an attempt to analyze the underlying geodynamic process that caused the swarm. We utilize the relocated hypocenters monitored by local networks to examine the b-value characteristics for the swarm. This is best represented in a cross section showing two domains of higher b-value anomalies: two patches occurring at shallow depth and at the deeper crust to the SE from the mainshock originated at the shallower depth northwestward. Consistently positive ΔCFF pattern with a large percentage of aftershocks imply how the mainshock rupture controlled the aftershocks activity. This implies that the failure along the NNW fault trend is due to the prevailing ambient stress field imparted to the swarm. We model this by CSF associated with the mainshock for three time dependent situations: (a) foreshock and aftershock epicenters, (b) foreshock hypocenters, and (c) aftershock hypocenters. In actuality, multiple factors might have controlled the aftershock activity as we speculate that positive Coulomb stress was associated in an area where the higher b-value prevails. The CSF produced by the mainshock illustrates how the stress dissipated along the NNW normal fault zone that interrupts the Great Dykes along the Red Sea coast. These results further suggest that the crustal

Prognostic value of cardiac power output to left ventricular mass in patients with left ventricular dysfunction and dobutamine stress echo negative by wall motion criteria.

PubMed

Cortigiani, Lauro; Sorbo, Simone; Miccoli, Mario; Scali, Maria Chiara; Simioniuc, Anca; Morrone, Doralisa; Bovenzi, Francesco; Marzilli, Mario; Dini, Frank Lloyd

2017-02-01

Cardiac power output to left ventricular mass (power/mass) is an index of myocardial efficiency reflecting the rate at which cardiac work is delivered with respect to the potential energy stored in the left ventricular mass. In the present study, we sought to investigate the capability of power/mass assessed at peak of dobutamine stress echocardiography to predict mortality in patients with ischaemic cardiomyopathy and no inducible ischaemia. One-hundred eleven patients (95 males; age 68 ± 10 years) with 35 ± 7% mean left ventricular ejection fraction and a dobutamine stress echocardiography (up to 40 µg/kg/min) negative by wall motion criteria formed the study population. Power/mass at peak stress was obtained as the product of a constant (K = 2.22 × 10 -1 ) with cardiac output and the mean arterial pressure divided by left ventricular mass to convert the units to W/100 g. Patients were followed up for a median of 29 months (inter-quartile range 16-72 months). All-cause mortality was the only accepted clinical end point. Mean peak-stress power/mass was 0.70 ± 0.31 W/100 g. During follow-up, 29 deaths (26%) were registered. With a receiver operating characteristic analysis, a peak-stress power/mass ≤0.50 W/100 g [area under curve 0.72 (95% CI 0.63; 0.80), sensitivity 59%, specificity 80%] was the best value for predicting mortality. Univariate prognostic indicators were age, male sex, peak-stress ejection fraction, peak-stress stroke volume, peak-stress cardiac output, peak-stress cardiac power output ≤1.48 W, and peak-stress power/mass ≤0.50 W/100 g. At multivariate analysis, age (HR 1.08, 95% CI 1.04; 1.14; P = 0.004) and peak-stress power/mass ≤0.50 W/100 g (HR 4.05, 95% CI 1.36; 12.00; P = 0.01) provided independent prognostic information. Three-year mortality was 14% in patients with peak-stress power/mass >0.50 W/100 g and 47% in those with peak-stress power/mass ≤0.50 W/100 g (log-rank 20.4; P < 0.0001). Power/mass assessed at peak of

Academic stress and positive affect: Asian value and self-worth contingency as moderators among Chinese international students.

PubMed

Liao, Kelly Yu-Hsin; Wei, Meifen

2014-01-01

The theoretical model proposed by Berry and colleagues (Berry, 1997; Berry, Kim, Minde, & Mok, 1987) highlights the importance of identifying moderators in the acculturation process. Accordingly, the current study examined the Asian cultural value of family recognition through achievement (FRTA) and contingency of self-worth on academic competence (CSW-AC) as moderators in the association between academic stress and positive affect among Chinese international students. A total of 370 Chinese international students completed online surveys. Results from a hierarchical regression indicated that while academic stress was negatively associated with positive affect, FRTA was positively associated with positive affect. In other words, those with high academic stress reported a lower level of positive affect. However, individuals who endorsed high levels of FRTA reported a higher level of positive affect. In addition, results also revealed a significant interaction between academic stress and CSW-AC on positive affect. Thus, the study's finding supported the moderator role of CSW-AC. Simple effect analyses were conducted to examine the significant interaction. The results showed that higher levels of CSW-AC strengthened the negative association between academic stress and positive affect but lower levels of CSW-AC did not. Future research directions and implications are discussed.

Determining Baseline Stress-Related Hormone Values in Large Cetaceans

DTIC Science & Technology

2014-09-30

reconstructed chemical profiles provided a unique window into stress-related hormone (cortisol, aldosterone , T3 and T4) concentrations and...Stress-related hormone radioimmunoassay technique Cortisol, aldosterone , hormones thyroxine (T4) and triiodothyronine (T3) levels in each identified...contaminant concentrations will be calculated using Pearson correlation coefficients. These measurements will include all hormones ( aldosterone , T3

Evaluating Renewable Groundwater Stress with GRACE data in Greece

NASA Astrophysics Data System (ADS)

Lakshmi, V.; Gemitzi, A.

2016-12-01

Groundwater is a resilient water source and its importance as a fundamental resource is even greater in times of drought where groundwater stress conditions are greatest for areas like Mediterranean and adverse climate change effects are expected. The present study evaluates Renewable Groundwater Stress (RGS) as the ratio of groundwater use to groundwater availability, quantifying use as the trend in GRACE-derived subsurface anomalies (ΔGWtrend) and renewable groundwater availability as mean annual recharge. Estimates for mean annual recharge were used from groundwater studies conducted for the various regions in Greece, mainly in the form of numerical models. Our results highlighted two RGS regimes in Greece out of the four characteristic stress regimes, i.e. Overstressed, Variable Stress, Human-Dominated Stress and Unstressed, defined as a function of the sign of use and the sign of groundwater availability (positive or negative). Variable Stress areas are found in central Greece (Thessaly region), where intense agricultural activities take place, with negative ΔGWtrend values combined with positive mean annual recharge rates. RGS values range from -0.05 - 0, indicating however a low impact area. Within this region, adverse effects of groundwater overexploitation are already evident, based on the negative GRACE anomalies, recharge however still remains positive, amending the adverse over pumping impacts. The rest of Greek aquifers fall within the unstressed category, with RGS values from 0.02 - 0.05, indicating that the rate of use is less than the natural recharge rate. The highest Unstressed RGS values are observed in Crete Island and in Northeastern Greece. However, the case of Crete is highly uncertain, as precipitation and recharge in this area demonstrate exceptionally high variability and the coarse resolution of GRACE results does not allow for reliable estimates.

Ecological comparison of cellular stress responses among populations - normalizing RT-qPCR values to investigate differential environmental adaptations.

PubMed

Koenigstein, Stefan; Pöhlmann, Kevin; Held, Christoph; Abele, Doris

2013-05-16

Rising temperatures and other environmental factors influenced by global climate change can cause increased physiological stress for many species and lead to range shifts or regional population extinctions. To advance the understanding of species' response to change and establish links between individual and ecosystem adaptations, physiological reactions have to be compared between populations living in different environments. Although changes in expression of stress genes are relatively easy to quantify, methods for reliable comparison of the data remain a contentious issue. Using normalization algorithms and further methodological considerations, we compare cellular stress response gene expression levels measured by RT-qPCR after air exposure experiments among different subpopulations of three species of the intertidal limpet Nacella. Reference gene assessment algorithms reveal that stable reference genes can differ among investigated populations and / or treatment groups. Normalized expression values point to differential defense strategies to air exposure in the investigated populations, which either employ a pronounced cellular stress response in the inducible Hsp70 forms, or exhibit a comparatively high constitutive expression of Hsps (heat shock proteins) while showing only little response in terms of Hsp induction. This study serves as a case study to explore the methodological prerequisites of physiological stress response comparisons among ecologically and phylogenetically different organisms. To improve the reliability of gene expression data and compare the stress responses of subpopulations under potential genetic divergence, reference gene stability algorithms are valuable and necessary tools. As the Hsp70 isoforms have been shown to play different roles in the acute stress responses and increased constitutive defenses of populations in their different habitats, these comparative studies can yield insight into physiological strategies of adaptation to

Stress drop estimates and hypocenter relocations of induced earthquakes near Fox Creek, Alberta

NASA Astrophysics Data System (ADS)

Clerc, F.; Harrington, R. M.; Liu, Y.; Gu, Y. J.

2016-12-01

This study investigates the physical differences between induced and naturally occurring earthquakes using a sequence of events potentially induced by hydraulic fracturing near Fox Creek, Alberta. We perform precise estimations of static stress drop to determine if the range of values is low compared to values estimated for naturally occurring events, as has been suggested by previous studies. Starting with the Natural Resources Canada earthquake catalog and using waveform data from regional networks, we use a spectral ratio method to calculate the static stress drop values of a group of relocated earthquakes occurring in close proximity to hydraulic fracturing wells from December 2013 to June 2015. The spectral ratio method allows us to precisely constrain the corner frequencies of the amplitude spectra by eliminating the path and site effects of co-located event pairs. Our estimated stress drop values range from 0.1 - 149 MPa over the full range of observed magnitudes, Mw 1.5-4, which are on the high side of the typical reported range of tectonic events, but consistent with other regional studies [Zhang et al., 2016; Wang et al., 2016]. , Stress drops values range from 11 to 93 MPa and appear to be scale invariant over the magnitude range Mw 3 - 4, and are less well constrained at lower magnitudes due to noise and bandwidth limitations. We observe no correlation between event stress drop and hypocenter depth or distance from the wells. Relocated hypocenters cluster around corresponding injection wells and form fine-scale lineations, suggesting the presence and orientation of fault planes. We conclude that neither the range of stress drops nor their scaling with respect to magnitude can be used to conclusively discriminate induced and tectonic earthquakes, as stress drop values may be greatly affected by the regional setting. Instead, the double-difference relocations may be a more reliable indicator of induced seismicity.

High precision analytical description of the allowed β spectrum shape

NASA Astrophysics Data System (ADS)

Hayen, Leendert; Severijns, Nathal; Bodek, Kazimierz; Rozpedzik, Dagmara; Mougeot, Xavier

2018-01-01

A fully analytical description of the allowed β spectrum shape is given in view of ongoing and planned measurements. Its study forms an invaluable tool in the search for physics beyond the standard electroweak model and the weak magnetism recoil term. Contributions stemming from finite size corrections, mass effects, and radiative corrections are reviewed. Particular focus is placed on atomic and chemical effects, where the existing description is extended and analytically provided. The effects of QCD-induced recoil terms are discussed, and cross-checks were performed for different theoretical formalisms. Special attention was given to a comparison of the treatment of nuclear structure effects in different formalisms. Corrections were derived for both Fermi and Gamow-Teller transitions, and methods of analytical evaluation thoroughly discussed. In its integrated form, calculated f values were in agreement with the most precise numerical results within the aimed for precision. The need for an accurate evaluation of weak magnetism contributions was stressed, and the possible significance of the oft-neglected induced pseudoscalar interaction was noted. Together with improved atomic corrections, an analytical description was presented of the allowed β spectrum shape accurate to a few parts in 10-4 down to 1 keV for low to medium Z nuclei, thereby extending the work by previous authors by nearly an order of magnitude.

Determining Baseline Stress-Related Hormone Values in Large Cetaceans

DTIC Science & Technology

2015-09-30

individual whale. These reconstructed chemical profiles provided a unique window into stress-related hormone (cortisol, aldosterone , T3 and T4...stored under nitrogen at -30 °C. Stress-related hormone radioimmunoassay technique Cortisol, aldosterone , hormones thyroxine (T4) and...coefficients. These measurements will include all hormones ( aldosterone , T3, T4, and cortisol) as well as contaminants. The age trends for the 6 hormones will

Four-point bend apparatus for in situ micro-Raman stress measurements

NASA Astrophysics Data System (ADS)

Ward, Shawn H.; Mann, Adrian B.

2018-06-01

A device for in situ use with a micro-Raman microscope to determine stress from the Raman peak position was designed and validated. The device is a four-point bend machine with a micro-stepping motor and load cell, allowing for fine movement and accurate readings of the applied force. The machine has a small footprint and easily fits on most optical microscope stages. The results obtained from silicon are in good agreement with published literature values for the linear relationship between stress and peak position for the 520.8 cm‑1 Raman peak. The device was used to examine 4H–SiC and a good linear relationship was found between the 798 cm‑1 Raman peak position and stress, with the proportionality coefficient being close to the theoretical value of 0.0025. The 777 cm‑1 Raman peak also showed a linear dependence on stress, but the dependence was not as strong. The device examines both the tensile and compressive sides of the beam in bending, granting the potential for many materials and crystal orientations to be examined.

Parenting Values and Parenting Stress among Impoverished Village and Middle-Class Small City Mothers in the Dominican Republic

ERIC Educational Resources Information Center

Foucault, Darlene C.; Schneider, Barry H.

2009-01-01

Poverty is known to influence parenting values, parenting stress, psychological adjustment, and social support according to North American research. The purpose of this study was to determine whether poverty might work in similar ways in a collectivistic Latin culture. The participants were primary caregivers in two distinct communities in the…

Persistent damaged bases in DNA allow mutagenic break repair in Escherichia coli

PubMed Central

Moore, Jessica M.; Correa, Raul; Rosenberg, Susan M.

2017-01-01

Bacteria, yeast and human cancer cells possess mechanisms of mutagenesis upregulated by stress responses. Stress-inducible mutagenesis potentially accelerates adaptation, and may provide important models for mutagenesis that drives cancers, host pathogen interactions, antibiotic resistance and possibly much of evolution generally. In Escherichia coli repair of double-strand breaks (DSBs) becomes mutagenic, using low-fidelity DNA polymerases under the control of the SOS DNA-damage response and RpoS general stress response, which upregulate and allow the action of error-prone DNA polymerases IV (DinB), II and V to make mutations during repair. Pol IV is implied to compete with and replace high-fidelity DNA polymerases at the DSB-repair replisome, causing mutagenesis. We report that up-regulated Pol IV is not sufficient for mutagenic break repair (MBR); damaged bases in the DNA are also required, and that in starvation-stressed cells, these are caused by reactive-oxygen species (ROS). First, MBR is reduced by either ROS-scavenging agents or constitutive activation of oxidative-damage responses, both of which reduce cellular ROS levels. The ROS promote MBR other than by causing DSBs, saturating mismatch repair, oxidizing proteins, or inducing the SOS response or the general stress response. We find that ROS drive MBR through oxidized guanines (8-oxo-dG) in DNA, in that overproduction of a glycosylase that removes 8-oxo-dG from DNA prevents MBR. Further, other damaged DNA bases can substitute for 8-oxo-dG because ROS-scavenged cells resume MBR if either DNA pyrimidine dimers or alkylated bases are induced. We hypothesize that damaged bases in DNA pause the replisome and allow the critical switch from high fidelity to error-prone DNA polymerases in the DSB-repair replisome, thus allowing MBR. The data imply that in addition to the indirect stress-response controlled switch to MBR, a direct cis-acting switch to MBR occurs independently of DNA breakage, caused by ROS

Persistent damaged bases in DNA allow mutagenic break repair in Escherichia coli.

PubMed

Moore, Jessica M; Correa, Raul; Rosenberg, Susan M; Hastings, P J

2017-07-01

Bacteria, yeast and human cancer cells possess mechanisms of mutagenesis upregulated by stress responses. Stress-inducible mutagenesis potentially accelerates adaptation, and may provide important models for mutagenesis that drives cancers, host pathogen interactions, antibiotic resistance and possibly much of evolution generally. In Escherichia coli repair of double-strand breaks (DSBs) becomes mutagenic, using low-fidelity DNA polymerases under the control of the SOS DNA-damage response and RpoS general stress response, which upregulate and allow the action of error-prone DNA polymerases IV (DinB), II and V to make mutations during repair. Pol IV is implied to compete with and replace high-fidelity DNA polymerases at the DSB-repair replisome, causing mutagenesis. We report that up-regulated Pol IV is not sufficient for mutagenic break repair (MBR); damaged bases in the DNA are also required, and that in starvation-stressed cells, these are caused by reactive-oxygen species (ROS). First, MBR is reduced by either ROS-scavenging agents or constitutive activation of oxidative-damage responses, both of which reduce cellular ROS levels. The ROS promote MBR other than by causing DSBs, saturating mismatch repair, oxidizing proteins, or inducing the SOS response or the general stress response. We find that ROS drive MBR through oxidized guanines (8-oxo-dG) in DNA, in that overproduction of a glycosylase that removes 8-oxo-dG from DNA prevents MBR. Further, other damaged DNA bases can substitute for 8-oxo-dG because ROS-scavenged cells resume MBR if either DNA pyrimidine dimers or alkylated bases are induced. We hypothesize that damaged bases in DNA pause the replisome and allow the critical switch from high fidelity to error-prone DNA polymerases in the DSB-repair replisome, thus allowing MBR. The data imply that in addition to the indirect stress-response controlled switch to MBR, a direct cis-acting switch to MBR occurs independently of DNA breakage, caused by ROS

Postseismic viscoelastic deformation and stress. Part 2: Stress theory and computation; dependence of displacement, strain, and stress on fault parameters

NASA Technical Reports Server (NTRS)

Cohen, S. C.

1979-01-01

A viscoelastic model for deformation and stress associated with earthquakes is reported. The model consists of a rectangular dislocation (strike slip fault) in a viscoelastic layer (lithosphere) lying over a viscoelastic half space (asthenosphere). The time dependent surface stresses are analyzed. The model predicts that near the fault a significant fraction of the stress that was reduced during the earthquake is recovered by viscoelastic softening of the lithosphere. By contrast, the strain shows very little change near the fault. The model also predicts that the stress changes associated with asthenospheric flow extend over a broader region than those associated with lithospheric relaxation even though the peak value is less. The dependence of the displacements, stresses on fault parameters studied. Peak values of strain and stress drop increase with increasing fault height and decrease with fault depth. Under many circumstances postseismic strains and stresses show an increase with decreasing depth to the lithosphere-asthenosphere boundary. Values of the strain and stress at distant points from the fault increase with fault area but are relatively insensitive to fault depth.

15 CFR 241.7 - Tolerances to be allowed.

Code of Federal Regulations, 2010 CFR

2010-01-01

... cranberries, shall be the values given in the following table, and these tolerances are to be applied to the... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Tolerances to be allowed. 241.7..., VEGETABLES AND OTHER DRY COMMODITIES, AND FOR CRANBERRIES § 241.7 Tolerances to be allowed. (a) The...

Development of a shear stress sensor to analyse the influence of polymers on the turbulent wall shear stress.

PubMed

Nottebrock, Bernardo; Grosse, Sebastian; Schröder, Wolfgang

2011-05-11

The drag reducing effect of polymers in a channel flow is well known and it is assumed that the polymer filaments interfere with the turbulent structures in the very near-wall flow. To analyse their precise effect, a micro-pillar shear stress sensor (MPS³) measurement system is developed which allows the detection of wall shear stress at high spatial and temporal resolutions. Different manufacturing techniques for the required micro-pillars are discussed and their influence on the flow is investigated evidencing the non-intrusive character of the pillars. Subsequently, a complete calibration is presented to relate the recorded deflection to wall shear stress values and to assure the correct detection over the whole expected frequency spectrum. A feasibility study about the ability to visualize the two-dimensional wall shear stress distribution completes the discussion about the validity of MPS³. In the last step, the drag reduction of a polymer filament grafted on a micro-pillar compared to a plain pillar and the application of MPS³ in an ocean-type polymer solution are investigated. The results confirm the expected behaviour found in the literature.

Sea-Level Allowances along the World Coastlines

NASA Astrophysics Data System (ADS)

Vandewal, R.; Tsitsikas, C.; Reerink, T.; Slangen, A.; de Winter, R.; Muis, S.; Hunter, J. R.

2017-12-01

Sea level changes as a result of climate change. For projections we take ocean mass changes and volume changes into account. Including gravitational and rotational fingerprints this provide regional sea level changes. Hence we can calculate sea-level rise patterns based on CMIP5 projections. In order to take the variability around the mean state, which follows from the climate models, into account we use the concept of allowances. The allowance indicates the height a coastal structure needs to be increased to maintain the likelihood of sea-level extremes. Here we use a global reanalysis of storm surges and extreme sea levels based on a global hydrodynamic model in order to calculate allowances. It is shown that the model compares in most regions favourably with tide gauge records from the GESLA data set. Combining the CMIP5 projections and the global hydrodynamical model we calculate sea-level allowances along the global coastlines and expand the number of points with a factor 50 relative to tide gauge based results. Results show that allowances increase gradually along continental margins with largest values near the equator. In general values are lower at midlatitudes both in Northern and Southern Hemisphere. Increased risk for extremes are typically 103-104 for the majority of the coastline under the RCP8.5 scenario at the end of the century. Finally we will show preliminary results of the effect of changing wave heights based on the coordinated ocean wave project.

Friction Stir Weld Restart+Reweld Repair Allowables

NASA Technical Reports Server (NTRS)

Clifton, Andrew

2008-01-01

A friction stir weld (FSW) repair method has been developed and successfully implemented on Al 2195 plate material for the Space Shuttle External Fuel Tank (ET). The method includes restarting the friction stir weld in the termination hole of the original weld followed by two reweld passes. Room temperature and cryogenic temperature mechanical properties exceeded minimum FSW design strength and compared well with the development data. Simulated service test results also compared closely to historical data for initial FSW, confirming no change to the critical flaw size or inspection requirements for the repaired weld. Testing of VPPA fusion/FSW intersection weld specimens exhibited acceptable strength and exceeded the minimum design value. Porosity, when present at the intersection was on the root side toe of the fusion weld, the "worst case" being 0.7 inch long. While such porosity may be removed by sanding, this "worst case" porosity condition was tested "as is" and demonstrated that porosity did not negatively affect the strength of the intersection weld. Large, 15-inch "wide panels" FSW repair welds were tested to demonstrate strength and evaluate residual stresses using photo stress analysis. All results exceeded design minimums, and photo stress analysis showed no significant stress gradients due to the presence of the restart and multi-pass FSW repair weld.

Ecological comparison of cellular stress responses among populations – normalizing RT-qPCR values to investigate differential environmental adaptations

PubMed Central

2013-01-01

Background Rising temperatures and other environmental factors influenced by global climate change can cause increased physiological stress for many species and lead to range shifts or regional population extinctions. To advance the understanding of species’ response to change and establish links between individual and ecosystem adaptations, physiological reactions have to be compared between populations living in different environments. Although changes in expression of stress genes are relatively easy to quantify, methods for reliable comparison of the data remain a contentious issue. Using normalization algorithms and further methodological considerations, we compare cellular stress response gene expression levels measured by RT-qPCR after air exposure experiments among different subpopulations of three species of the intertidal limpet Nacella. Results Reference gene assessment algorithms reveal that stable reference genes can differ among investigated populations and / or treatment groups. Normalized expression values point to differential defense strategies to air exposure in the investigated populations, which either employ a pronounced cellular stress response in the inducible Hsp70 forms, or exhibit a comparatively high constitutive expression of Hsps (heat shock proteins) while showing only little response in terms of Hsp induction. Conclusions This study serves as a case study to explore the methodological prerequisites of physiological stress response comparisons among ecologically and phylogenetically different organisms. To improve the reliability of gene expression data and compare the stress responses of subpopulations under potential genetic divergence, reference gene stability algorithms are valuable and necessary tools. As the Hsp70 isoforms have been shown to play different roles in the acute stress responses and increased constitutive defenses of populations in their different habitats, these comparative studies can yield insight into

Maslow and Values Education

ERIC Educational Resources Information Center

Farmer, Rodney

1978-01-01

Identifies major value bases which have been used to teach values in the classroom and outlines a values education program which stresses teaching about values without indoctrination. Based upon the hierarchy of human needs developed by psychologist Abraham Maslow, the program is based upon universal values, basic human needs, and recognition of…

Stress mitigation to promote development of prosocial values and school engagement of inner-city urban African American and Latino youth.

PubMed

Tolan, Patrick; Lovegrove, Peter; Clark, Eren

2013-01-01

Studies of predictors of development of young men of color have been primarily focused on factors that impede positive development rather than factors that promote it. There are also few examples of longitudinal studies of positive development of this population and few that consider multiple protective factors simultaneously. Little is also known about how such positive outcomes might relate to prediction of problematic functioning. This study tests a developmental-ecological framework of positive and risky development among a sample of young men of color growing up in high-risk urban environments. African American and Latino adolescent males (148 African American, 193 Latino) were followed from early to late adolescence. Stress in early adolescence was related to school engagement and prosocial values as well as depressive symptoms and problems assessed 2 years later. The role of family and individual protective factors as direct effects and as mitigating the stress-outcome relation were also tested. Stress predicted problem outcomes but not positive functioning. Early engagement in prosocial activities and coping skills did predict positive outcomes. In contrast, problem outcomes were predicted directly by stress, with some indication of interaction with some protective factors for both such outcomes. Overall results suggest value in focusing on positive outcomes along with negative outcomes, as they are not the antithesis and have some shared but some different predictors. Implications for supporting positive development are presented. © 2013 American Orthopsychiatric Association.

How and when do personal values guide our attitudes and sociality? Explaining cross-cultural variability in attitude-value linkages.

PubMed

Boer, Diana; Fischer, Ronald

2013-09-01

This article examines how and when personal values relate to social attitudes. Considering values as motivational orientations, we propose an attitude-value taxonomy based on Moral Foundation Theory (Haidt & Joseph, 2007) and Schwartz's (1992) basic human values theory allowing predictions of (a) how social attitudes are related to personal values, and (b) when macro-contextual factors have an impact on attitude-value links. In a meta-analysis based on the Schwartz Value Survey (Schwartz, 1992) and the Portrait Value Questionnaire (Schwartz et al., 2001; k = 91, N = 30,357 from 31 countries), we found that self-transcendence (vs. self-enhancement) values relate positively to fairness/proenvironmental and care/prosocial attitudes, and conservation (vs. openness-to-change) values relate to purity/religious and authority/political attitudes, whereas ingroup/identity attitudes are not consistently associated with value dimensions. Additionally, we hypothesize that the ecological, economic, and cultural context moderates the extent to which values guide social attitudes. Results of the multi-level meta-analysis show that ecological and cultural factors inhibit or foster attitude-value associations: Disease stress is associated with lower attitude-value associations for conservation (vs. openness-to-change) values; collectivism is associated with stronger attitude-value links for conservation values; individualism is associated with stronger attitude-value links for self-transcendence (vs. self-enhancement) values; and uncertainty avoidance is associated with stronger attitude-values links, particularly for conservation values. These findings challenge universalistic claims about context-independent attitude-value relations and contribute to refined future value and social attitude theories. (c) 2013 APA, all rights reserved.

Deformation of a geo-medium with considering for internal self-balancing stresses

NASA Astrophysics Data System (ADS)

Lavrikov, S. V.; Revuzhenko, A. F.

2016-11-01

Based on the general concept of rock as a medium with inner sources and sinks of energy, the authors consider an approach to mathematical modeling of a geo-medium with account for internal self-balancing stresses. The description of stresses and strains at the level of microstructural elements and macrovolume of the medium uses methods of non-Archimedean analysis. The model allows describing the accumulation of elastic energy in the form of internal self-balancing stresses. A finite element algorithm and a software program for solving plane boundary-value problems have been developed. The calculated data on rock specimen compression are given. It is shown that the behavior of plastic deformation zones depends on the pre-assigned initial microstresses.

[Effects of lead stress on net photosynthetic rate, SPAD value and ginsenoside production in Ginseng (Panax ginseng)].

PubMed

Liang, Yao; Jiang, Xiao-Li; Yang, Fen-Tuan; Cao, Qing-Jun; Li, Gang

2014-08-01

The paper aimed to evaluate the effects of lead stress on photosynthetic performance and ginsenoside content in ginseng (Panax ginseng). To accomplish this, three years old ginseng were cultivated in pot and in phytotron with different concentrations of lead, ranging from 0 to 1000 mg x kg(-1) soil for a whole growth period (about 150 days). The photosynthetic parameters in leaves and ginsenoside content in roots of ginseng were determined in green fruit stage and before withering stage, respectively. In comparison with the control, net photosynthetic rate and SPAD value in ginseng leaves cultivated with 100 and 250 mg x kg(-1) of lead changed insignificantly, however, ginseng supplied with 500 and 1 000 mg x kg(-1) of lead showed a noticeably decline in the net rate of photosynthesis and SPAD value (P < 0.05), the lowest net photosynthetic rate and SPAD value showed in the treatment supplied with 1 000 mg x kg(-1) of lead, with decline of 57.8%,11.0%, respectively. Total content of ginsenoside in ginseng roots cultivated with 100 mg x kg(-1) of lead showed insignificantly change compared to the control, but the content increased remarkably in treatments supplied with 250, 500, 1 000 mg x kg(-1) of lead (P < 0.05), and highest content appeared in these ginsengs exposed to 1000 mg x kg(-1) of lead. The net photosynthetic rate and SPAD value in leaves of ginseng both showed significantly negative linear correlations with lead stress level (P < 0.01), and significant positive linear correlations between total content of ginsenoside and lead concentration was also observed (P < 0.05). These results strongly indicate that exposing to high level of lead negatively affects photosynthetic performance in ginseng leaves, but benefits for accumulation of secondary metabolism (total content of ginsenoside) in ginseng root.

The endocannabinoid system in guarding against fear, anxiety and stress.

PubMed

Lutz, Beat; Marsicano, Giovanni; Maldonado, Rafael; Hillard, Cecilia J

2015-12-01

The endocannabinoid (eCB) system has emerged as a central integrator linking the perception of external and internal stimuli to distinct neurophysiological and behavioural outcomes (such as fear reaction, anxiety and stress-coping), thus allowing an organism to adapt to its changing environment. eCB signalling seems to determine the value of fear-evoking stimuli and to tune appropriate behavioural responses, which are essential for the organism's long-term viability, homeostasis and stress resilience; and dysregulation of eCB signalling can lead to psychiatric disorders. An understanding of the underlying neural cell populations and cellular processes enables the development of therapeutic strategies to mitigate behavioural maladaptation.

The endocannabinoid system in guarding against fear, anxiety and stress

PubMed Central

Lutz, Beat; Marsicano, Giovanni; Maldonado, Rafael; Hillard, Cecilia J.

2018-01-01

The endocannabinoid (eCB) system has emerged as a central integrator linking the perception of external and internal stimuli to distinct neurophysiological and behavioural outcomes (such as fear reaction, anxiety and stress-coping), thus allowing an organism to adapt to its changing environment. eCB signalling seems to determine the value of fear-evoking stimuli and to tune appropriate behavioural responses, which are essential for the organism’s long-term viability, homeostasis and stress resilience; and dysregulation of eCB signalling can lead to psychiatric disorders. An understanding of the underlying neural cell populations and cellular processes enables the development of therapeutic strategies to mitigate behavioural maladaptation. PMID:26585799

40 CFR 35.2025 - Allowance and advance of allowance.

Code of Federal Regulations, 2010 CFR

2010-07-01

... advance of allowance. (a) Allowance. Step 2+3 and Step 3 grant agreements will include an allowance for facilities planning and design of the project and Step 7 agreements will include an allowance for facility... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Allowance and advance of allowance. 35...

Modeling two-dimensional crystals and nanotubes with defects under stress

NASA Astrophysics Data System (ADS)

Dietel, Jürgen; Kleinert, Hagen

2009-06-01

We calculate analytically the phase diagram of a two-dimensional planar crystal and its wrapped version with defects under external homogeneous stress as a function of temperature using a simple elastic square lattice model that allows for defect formation. The temperature dependence turns out to be very weak. The results are relevant for recent stress experiments on carbon nanotubes at high temperatures. Under increasing stress, we find a crossover regime which we identify with a cracking transition that is almost independent of temperature. Furthermore, we find an almost stress-independent melting point. In addition, we derive an enhanced ductility with relative strains before cracking between 200% and 400%, in agreement with carbon nanotube experiments. The specific values depend on the Poisson ratio and the angle between the external force and the crystal axes. We give arguments that the results for carbon nanotubes should be not much different from these results in spite of the different lattice structures.

Relationship between general intelligence, emotional intelligence, stress levels and stress reactivity.

PubMed

Singh, Yogesh; Sharma, Ratna

2012-07-01

Stressful life events and daily life stresses have both deleterious and cumulative effects on human body. In several studies, stress has been shown to affect various parameter of higher mental function like attention, concentration, learning and memory. Present study was designed to explore the relationship among GI level, EI level, psychological stress levels and acute stress reactivity in young normal healthy subjects. The study was conducted on thirty four healthy male student volunteers to study a) acute stress reactivity in subjects with varying levels of General Intelligence (GI) and Emotional Intelligence (EI) and b) correlation between GI, EI, acute stress and perceived stress. Baseline GI and EI and acute stress and perceived stress scores were measured by standard assessment scales. Using median value of GI and EI scores as cutoff values, subjects were categorized into four groups. Among different GI-EI groups, acute stress reactivity was similar but salivary Cortisol (especially post stressor level) and perceived stress level was a differentiating factor. High level of EI was associated inversely with acute and chronic perceived stress level. Significant correlation was found between acute and chronic perceived stress levels. Level of general intelligence showed no relation to acute or chronic stress levels as well as acute stress reactivity. The differences in various groups of GI and EI had no effect on the baseline and post stress performance on Sternberg memory test and all the three conditions of Stroop test. In conclusion emotional intelligence as an attribute is better suited to handle day to day acute stress and chronic perceived stress.

Lithology-dependent minimum horizontal stress and in-situ stress estimate

NASA Astrophysics Data System (ADS)

Zhang, Yushuai; Zhang, Jincai

2017-04-01

Based on the generalized Hooke's law with coupling stresses and pore pressure, the minimum horizontal stress is solved with assumption that the vertical, minimum and maximum horizontal stresses are in equilibrium in the subsurface formations. From this derivation, we find that the uniaxial strain method is the minimum value or lower bound of the minimum stress. Using Anderson's faulting theory and this lower bound of the minimum horizontal stress, the coefficient of friction of the fault is derived. It shows that the coefficient of friction may have a much smaller value than what it is commonly assumed (e.g., μf = 0.6-0.7) for in-situ stress estimate. Using the derived coefficient of friction, an improved stress polygon is drawn, which can reduce the uncertainty of in-situ stress calculation by narrowing the area of the conventional stress polygon. It also shows that the coefficient of friction of the fault is dependent on lithology. For example, if the formation in the fault is composed of weak shales, then the coefficient of friction of the fault may be small (as low as μf = 0.2). This implies that this fault is weaker and more likely to have shear failures than the fault composed of sandstones. To avoid the weak fault from shear sliding, it needs to have a higher minimum stress and a lower shear stress. That is, the critically stressed weak fault maintains a higher minimum stress, which explains why a low shear stress appears in the frictionally weak fault.

Analysis of Stress in Steel and Concrete in Cfst Push-Out Test Samples

NASA Astrophysics Data System (ADS)

Grzeszykowski, Bartosz; Szadkowska, Magdalena; Szmigiera, Elżbieta

2017-09-01

The paper presents the analysis of stress in steel and concrete in CFST composite elements subjected to push-out tests. Two analytical models of stress distribution are presented. The bond at the interface between steel and concrete in the initial phase of the push-out test is provided by the adhesion. Until the force reach a certain value, the slip between both materials does not occur or it is negligibly small, what ensures full composite action of the specimen. In the first analytical model the full bond between both materials was assumed. This model allows to estimate value of the force for which the local loss of adhesion in given cross section begins. In the second model it was assumed that the bond stress distribution is constant along the shear transfer length of the specimen. Based on that the formulas for triangle distribution of stress in steel and concrete for the maximum push-out force were derived and compared with the experimental results. Both models can be used to better understand the mechanisms of interaction between steel and concrete in composite steel-concrete columns.

30 CFR 1206.158 - Processing allowances-general.

Code of Federal Regulations, 2012 CFR

2012-07-01

... relationship. Natural gas liquids (NGL's) shall be considered as one product. (c)(1) Except as provided in... RESOURCES REVENUE PRODUCT VALUATION Federal Gas § 1206.158 Processing allowances—general. (a) Where the value of gas is determined pursuant to § 1206.153 of this subpart, a deduction shall be allowed for the...

30 CFR 1206.158 - Processing allowances-general.

Code of Federal Regulations, 2013 CFR

2013-07-01

... relationship. Natural gas liquids (NGL's) shall be considered as one product. (c)(1) Except as provided in... RESOURCES REVENUE PRODUCT VALUATION Federal Gas § 1206.158 Processing allowances—general. (a) Where the value of gas is determined pursuant to § 1206.153 of this subpart, a deduction shall be allowed for the...

30 CFR 1206.158 - Processing allowances-general.

Code of Federal Regulations, 2014 CFR

2014-07-01

... relationship. Natural gas liquids (NGL's) shall be considered as one product. (c)(1) Except as provided in... RESOURCES REVENUE PRODUCT VALUATION Federal Gas § 1206.158 Processing allowances—general. (a) Where the value of gas is determined pursuant to § 1206.153 of this subpart, a deduction shall be allowed for the...

Are Recommended Daily Allowances for Vitamin C Adequate?

PubMed Central

Pauling, Linus

1974-01-01

The Recommended Dietary Allowance of vitamin C (ascorbic acid) for adults has now been set at 45 mg day-1 by the U.S. Food and Nutrition Board. This intake suffices to prevent scurvy in most people. It is, however, much less than the optimum intake, the intake that leads to the best of health. A larger intake decreases the incidence and severity of the common cold and other diseases. Ascorbic acid has antiviral and antibacterial activity and is required for phagocytic activity of leukocytes. Several arguments indicate that for different human beings the optimum intake lies between 250 mg day-1 and a much higher value, 5000 mg day-1 or more. It is proposed that the present Recommended Dietary Allowance of 45 mg day-1 of vitamin C for adults be renamed the Minimum Dietary Allowance, defined as the amount needed to prevent scurvy, and that, after consideration of the evidence about intake and the best of health, there be formulated another category of values, the Recommended Daily Intake, with the suggested range of 250 mg day-1 to 4000 mg day-1 of ascorbic acid for an adult. PMID:4612519

SM-1 REACTOR VESSEL COVER AND FLANGE STRESS ANALYSIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sayre, M.F.

1962-02-19

The maximum stress calculated for the SMl-1 reactor vessel closure studs occurs during operation at full power. This value is 27,180 psi of which 19,800 psi is tension and 7380 psi bending. This stress does not include a stress concentration factor for effect of threads. It was eonservatively assumed the studs were initially tightened to a code allowable stress of 20,000 psi as specified in the ASME Code rather than the lesser stress obtained by the normal operating procedure. The maximum calculated stress occurs at the outside surface of the cover where the stress ranges from 318 psi in tensionmore » to 90,660 psi in compression. The alternating stress is 50,000 psi. According to the Navy Code for a stress range of 50,000 psi, the eover material ean safely undergo a maximum of 1600 cycles. It was estimated that the SM-1 will go through approximately 000 startup and shutdown cycles during a 20-yr life period, so the calculated stress is regarded as safe. For a transient eondition of 30 deg F/hr during heat-up, approximate temperature differences between the inside and outside surfaces of the cover were obtained. Temperature differentials between the inside and outside surfaces of the cover are increased by roughly 10%; above the steady state condition. More exact calculations of the transient stresses did not appear necessary siuce they would be not more than 10% greater than the steady state thermal stress. (auth)« less

Stress myocardial perfusion imaging in the emergency department--new techniques for speed and diagnostic accuracy.

PubMed

Harrison, Sheri D; Harrison, Mark A; Duvall, W Lane

2012-05-01

Emergency room evaluations of patients presenting with chest pain continue to rise, and these evaluations which often include cardiac imaging, are an increasing area of resource utilization in the current health system. Myocardial perfusion imaging from the emergency department remains a vital component of the diagnosis or exclusion of coronary artery disease as the etiology of chest pain. Recent advances in camera technology, and changes to the imaging protocols have allowed MPI to become a more efficient way of providing this diagnostic information. Compared with conventional SPECT, new high-efficiency CZT cameras provide a 3-5 fold increase in photon sensitivity, 1.65-fold improvement in energy resolution and a 1.7-2.5-fold increase in spatial resolution. With stress-only imaging, rest images are eliminated if stress images are normal, as they provide no additional prognostic or diagnostic value and cancelling the rest images would shorten the length of the test which is of particular importance to the ED population. The rapid but accurate triage of patients in an ED CPU is essential to their care, and stress-only imaging and new CZT cameras allow for shorter test time, lower radiation doses and lower costs while demonstrating good clinical outcomes. These changes to nuclear stress testing can allow for faster throughput of patients through the emergency department while providing a safe and efficient evaluation of chest pain.

The Value of Addressing Patient Preferences.

PubMed

Allen, Jeff D; Stewart, Mark D; Roberts, Samantha A; Sigal, Ellen V

2017-02-01

Recent scientific progress is, in some cases, leading to transformative new medicines for diseases that previously had marginal or even no treatment options. This offers great promise for people affected by these diseases, but it has also placed stress on the health care system in terms of the growing cost associated with some new interventions. Effort has been taken to create tools to help patients and health care providers assess the value of new medical innovations. These tools may also provide the basis for assessing the price associated with new medical products. Given the growing expenditures in health care, value frameworks present an opportunity to evaluate new therapeutic options in the context of other treatments and potentially lead to a more economically sustainable health care system. In summary, the contribution to meaningful improvements in health outcomes is the primary focus of any assessment of the value of a new intervention. A component of such evaluations, however, should factor in timely access to new products that address an unmet medical need, as well as the magnitude of that beneficial impact. To achieve these goals, value assessment tools should allow for flexibility in clinical end points and trial designs, incorporate patient preferences, and continually evolve as new evidence, practice patterns, and medical progress advance. Copyright © 2017 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

Photo-polymerization shrinkage-stress kinetics in resin-composites: methods development.

PubMed

Watts, D C; Marouf, A S; Al-Hindi, A M

2003-01-01

Studies of free shrinkage-strain kinetics on restoratives have begun to multiply. However, there have been fewer investigations of the more difficult problem of concurrent stress-kinetic measurements. The aim was to outline design parameters for a new methodology for this problem, amenable especially to light-cured materials, and to present illustrative results for a range of restorative composites. Absolute values of stress measurable for a given material and geometry are dependent upon the stiffness of the measurement system. In an infinitely stiff system, the measured stress would also tend towards infinity. Real teeth and their cavities are not infinitely stiff; they have elastic and visco-elastic compliance. Consequently, it is important that some minimal, but essentially constant compliance be allowed, whatever the final or time-dependent modulus of the material may be. This goal has been realised by measurement of the time-development, for a disk-geometry specimen (phi=10, h approximately 1.0 mm) of stress (S(r)), with a calibrated cantilever beam-geometry load cell. A novel specimen-holder design was used for this purpose, held in a rigid base assembly. Specimen thicknesses (or gap-widths) of 0.8 and 1.2 mm were specifically investigated on four representative resin-composites. Concurrent measurements were made of the end-displacement of the cantilever load cell, relative to a lower glass plate retaining the specimen. Load-calibration of the cantilever load cell gave an end-displacement per unit stress of circa 6 microm/MPa. This compares with literature values for cuspal compliance or displacement of circa 20 microm. Re-normalisation of the stress-data was implemented. This was accomplished assuming Hooke's law behavior at each instant and equivalent to a stiffer system, with a correction (multiplier) factor of 4 on the raw-stress values. For the materials examined, resultant maximum-stress levels determined were circa 5-8 MPa Stress-levels obtained at 1

Diversity of Survival Patterns among Escherichia coli O157:H7 Genotypes Subjected to Food-Related Stress Conditions.

PubMed

Elhadidy, Mohamed; Álvarez-Ordóñez, Avelino

2016-01-01

The purpose of this study was to evaluate the resistance patterns to food-related stresses of Shiga toxin producing Escherichia coli O157:H7 strains belonging to specific genotypes. A total of 33 E. coli O157:H7 strains were exposed to seven different stress conditions acting as potential selective pressures affecting the transmission of E. coli O157:H7 to humans through the food chain. These stress conditions included cold, oxidative, osmotic, acid, heat, freeze-thaw, and starvation stresses. The genotypes used for comparison included lineage-specific polymorphism, Shiga-toxin-encoding bacteriophage insertion sites, clade type, tir (A255T) polymorphism, Shiga toxin 2 subtype, and antiterminator Q gene allele. Bacterial resistance to different stressors was calculated by determining D-values (times required for inactivation of 90% of the bacterial population), which were then subjected to univariate and multivariate analyses. In addition, a relative stress resistance value, integrating resistance values to all tested stressors, was calculated for each bacterial strain and allowed for a ranking-type classification of E. coli O157:H7 strains according to their environmental robustness. Lineage I/II strains were found to be significantly more resistant to acid, cold, and starvation stress than lineage II strains. Similarly, tir (255T) and clade 8 encoding strains were significantly more resistant to acid, heat, cold, and starvation stress than tir (255A) and non-clade 8 strains. Principal component analysis, which allows grouping of strains with similar stress survival characteristics, separated strains of lineage I and I/II from strains of lineage II, which in general showed reduced survival abilities. Results obtained suggest that lineage I/II, tir (255T), and clade 8 strains, which have been previously reported to be more frequently associated with human disease cases, have greater multiple stress resistance than strains of other genotypes. The results from this

Diversity of Survival Patterns among Escherichia coli O157:H7 Genotypes Subjected to Food-Related Stress Conditions

PubMed Central

Elhadidy, Mohamed; Álvarez-Ordóñez, Avelino

2016-01-01

The purpose of this study was to evaluate the resistance patterns to food-related stresses of Shiga toxin producing Escherichia coli O157:H7 strains belonging to specific genotypes. A total of 33 E. coli O157:H7 strains were exposed to seven different stress conditions acting as potential selective pressures affecting the transmission of E. coli O157:H7 to humans through the food chain. These stress conditions included cold, oxidative, osmotic, acid, heat, freeze-thaw, and starvation stresses. The genotypes used for comparison included lineage-specific polymorphism, Shiga-toxin-encoding bacteriophage insertion sites, clade type, tir (A255T) polymorphism, Shiga toxin 2 subtype, and antiterminator Q gene allele. Bacterial resistance to different stressors was calculated by determining D-values (times required for inactivation of 90% of the bacterial population), which were then subjected to univariate and multivariate analyses. In addition, a relative stress resistance value, integrating resistance values to all tested stressors, was calculated for each bacterial strain and allowed for a ranking-type classification of E. coli O157:H7 strains according to their environmental robustness. Lineage I/II strains were found to be significantly more resistant to acid, cold, and starvation stress than lineage II strains. Similarly, tir (255T) and clade 8 encoding strains were significantly more resistant to acid, heat, cold, and starvation stress than tir (255A) and non-clade 8 strains. Principal component analysis, which allows grouping of strains with similar stress survival characteristics, separated strains of lineage I and I/II from strains of lineage II, which in general showed reduced survival abilities. Results obtained suggest that lineage I/II, tir (255T), and clade 8 strains, which have been previously reported to be more frequently associated with human disease cases, have greater multiple stress resistance than strains of other genotypes. The results from this

42 CFR 61.9 - Payments: Stipends; dependency allowances; travel allowances.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false Payments: Stipends; dependency allowances; travel... FELLOWSHIPS, INTERNSHIPS, TRAINING FELLOWSHIPS Regular Fellowships § 61.9 Payments: Stipends; dependency allowances; travel allowances. Payments for stipends, dependency allowances, and the travel allowances...

42 CFR 61.9 - Payments: Stipends; dependency allowances; travel allowances.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Payments: Stipends; dependency allowances; travel... FELLOWSHIPS, INTERNSHIPS, TRAINING FELLOWSHIPS Regular Fellowships § 61.9 Payments: Stipends; dependency allowances; travel allowances. Payments for stipends, dependency allowances, and the travel allowances...

42 CFR 61.9 - Payments: Stipends; dependency allowances; travel allowances.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Payments: Stipends; dependency allowances; travel... FELLOWSHIPS, INTERNSHIPS, TRAINING FELLOWSHIPS Regular Fellowships § 61.9 Payments: Stipends; dependency allowances; travel allowances. Payments for stipends, dependency allowances, and the travel allowances...

42 CFR 61.9 - Payments: Stipends; dependency allowances; travel allowances.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false Payments: Stipends; dependency allowances; travel... FELLOWSHIPS, INTERNSHIPS, TRAINING FELLOWSHIPS Regular Fellowships § 61.9 Payments: Stipends; dependency allowances; travel allowances. Payments for stipends, dependency allowances, and the travel allowances...

42 CFR 61.9 - Payments: Stipends; dependency allowances; travel allowances.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Payments: Stipends; dependency allowances; travel... FELLOWSHIPS, INTERNSHIPS, TRAINING FELLOWSHIPS Regular Fellowships § 61.9 Payments: Stipends; dependency allowances; travel allowances. Payments for stipends, dependency allowances, and the travel allowances...

Non-Contact Technique for Determining the Mechanical Stress in thin Films on Wafers by Profiler

NASA Astrophysics Data System (ADS)

Djuzhev, N. A.; Dedkova, A. A.; E Gusev, E.; Makhiboroda, M. A.; Glagolev, P. Y.

2017-04-01

This paper presents an algorithm for analysis of relief for the purpose of calculating mechanical stresses in a selected direction on the plate in the form of software package Matlab. The method allows for the measurement sample in the local area. It provides a visual representation of the data and allows to get stress distribution on wafer surface. Automated analysis process reduces the likelihood of errors researcher. Achieved time saving during processing results. In carrying out several measurements possible drawing card plate to predict yield crystals. According to this technique done in measurement of mechanical stresses of thermal silicon oxide film on a silicon substrate. Analysis of the results showed objectivity and reliability calculations. This method can be used for selecting the optimal parameters of the material deposition conditions. In software of device-technological simulation TCAD defined process time, temperature and oxidation of the operation of the sample environment for receiving the set value of the dielectric film thickness. Calculated thermal stresses are in the system silicon-silicon oxide. There is a good correlation between numerical simulations and analytical calculation. It is shown that the nature of occurrence of mechanical stress is not limited to the difference of thermal expansion coefficients of materials.

High temperature aqueous stress corrosion testing device

DOEpatents

Bornstein, A.N.; Indig, M.E.

1975-12-01

A description is given of a device for stressing tensile samples contained within a high temperature, high pressure aqueous environment, thereby permitting determination of stress corrosion susceptibility of materials in a simple way. The stressing device couples an external piston to an internal tensile sample via a pull rod, with stresses being applied to the sample by pressurizing the piston. The device contains a fitting/seal arrangement including Teflon and weld seals which allow sealing of the internal system pressure and the external piston pressure. The fitting/seal arrangement allows free movement of the pull rod and the piston.

Shear Stress-Normal Stress (Pressure) Ratio Decides Forming Callus in Patients with Diabetic Neuropathy

PubMed Central

Noguchi, Hiroshi; Takehara, Kimie; Ohashi, Yumiko; Suzuki, Ryo; Yamauchi, Toshimasa; Kadowaki, Takashi; Sanada, Hiromi

2016-01-01

Aim. Callus is a risk factor, leading to severe diabetic foot ulcer; thus, prevention of callus formation is important. However, normal stress (pressure) and shear stress associated with callus have not been clarified. Additionally, as new valuables, a shear stress-normal stress (pressure) ratio (SPR) was examined. The purpose was to clarify the external force associated with callus formation in patients with diabetic neuropathy. Methods. The external force of the 1st, 2nd, and 5th metatarsal head (MTH) as callus predilection regions was measured. The SPR was calculated by dividing shear stress by normal stress (pressure), concretely, peak values (SPR-p) and time integral values (SPR-i). The optimal cut-off point was determined. Results. Callus formation region of the 1st and 2nd MTH had high SPR-i rather than noncallus formation region. The cut-off value of the 1st MTH was 0.60 and the 2nd MTH was 0.50. For the 5th MTH, variables pertaining to the external forces could not be determined to be indicators of callus formation because of low accuracy. Conclusions. The callus formation cut-off values of the 1st and 2nd MTH were clarified. In the future, it will be necessary to confirm the effect of using appropriate footwear and gait training on lowering SPR-i. PMID:28050567

Prognostic value of high-dose dobutamine stress magnetic resonance imaging in 1,493 consecutive patients: assessment of myocardial wall motion and perfusion.

PubMed

Korosoglou, Grigorios; Elhmidi, Yacine; Steen, Henning; Schellberg, Dieter; Riedle, Nina; Ahrens, Johannes; Lehrke, Stephanie; Merten, Constanze; Lossnitzer, Dirk; Radeleff, Jannis; Zugck, Christian; Giannitsis, Evangelos; Katus, Hugo A

2010-10-05

This study sought to determine the prognostic value of wall motion and perfusion assessment during high-dose dobutamine stress (DS) cardiac magnetic resonance imaging (MRI) in a large patient cohort. DS-MRI offers the possibility to integrate myocardial perfusion and wall motion analysis in a single examination for the detection of coronary artery disease (CAD). A total of 1,493 consecutive patients with suspected or known CAD underwent DS-MRI, using a standard protocol in a 1.5-T magnetic resonance scanner. Wall motion and perfusion were assessed at baseline and during stress, and outcome data including cardiac death, nonfatal myocardial infarction ("hard events"), and "late" revascularization performed >90 days after the MR scans were collected during a 2 ± 1 year follow-up period. Fifty-three hard events, including 14 cardiac deaths and 39 nonfatal infarctions, occurred during the follow-up period, whereas 85 patients underwent "late" revascularization. Using multivariable regression analysis, an abnormal result for wall motion or perfusion during stress yielded the strongest independent prognostic value for both hard events and late revascularization, clearly surpassing that of clinical and baseline magnetic resonance parameters (for wall motion: adjusted hazard ratio [HR] of 5.9 [95% confidence interval (CI): 2.5 to 13.6] for hard events and of 3.1 [95% CI: 1.7 to 5.6] for late revascularization, and for perfusion: adjusted HR of 5.4 [95% CI: 2.3 to 12.9] for hard events and of 6.2 [95% CI: 3.3 to 11.3] for late revascularization, p < 0.001 for all). DS-MRI can accurately identify patients who are at increased risk for cardiac death and myocardial infarction, separating them from those with normal findings, who have very low risk for future cardiac events. (Prognostic Value of High Dose Dobutamine Stress Magnetic Resonance Imaging; NCT00837005). Copyright © 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Coping with Physiological Oxidative Stress: A Review of Antioxidant Strategies in Seals

PubMed Central

Vázquez-Medina, José Pablo; Zenteno-Savín, Tania; Elsner, Robert; Ortiz, Rudy M.

2012-01-01

While diving, seals are exposed to apnea-induced hypoxemia and repetitive cycles of ischemia/reperfusion. While on land, seals experience sleep apnea, as well as prolonged periods of food and water deprivation. Prolonged fasting, sleep apnea, hypoxemia and ischemia/reperfusion increase oxidant production and oxidative stress in terrestrial mammals. In seals, however, neither prolonged fasting nor apnea-induced hypoxemia or ischemia/reperfusion increase systemic or local oxidative damage. The strategies seals evolved to cope with increased oxidant production are reviewed in the present manuscript. Among these strategies, high antioxidant capacity and the oxidant-mediated activation of hormetic responses against hypoxia and oxidative stress are discussed. In addition to expanding our knowledge of the evolution of antioxidant defenses and adaptive responses to oxidative stress, understanding the mechanisms that allow adapted mammals to avoid oxidative damage has the potential to advance our knowledge of oxidative stress-induced pathologies and to enhance the translative value of biomedical therapies in the long term. PMID:22327141

5 CFR 2610.107 - Allowable fees and expenses.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 5 Administrative Personnel 3 2010-01-01 2010-01-01 false Allowable fees and expenses. 2610.107 Section 2610.107 Administrative Personnel OFFICE OF GOVERNMENT ETHICS ORGANIZATION AND PROCEDURES... factors as may bear on the value of the services provided. (d) The reasonable cost of any study, analysis...

Groundwater development stress: Global-scale indices compared to regional modeling

USGS Publications Warehouse

Alley, William; Clark, Brian R.; Ely, Matt; Faunt, Claudia

2018-01-01

The increased availability of global datasets and technologies such as global hydrologic models and the Gravity Recovery and Climate Experiment (GRACE) satellites have resulted in a growing number of global-scale assessments of water availability using simple indices of water stress. Developed initially for surface water, such indices are increasingly used to evaluate global groundwater resources. We compare indices of groundwater development stress for three major agricultural areas of the United States to information available from regional water budgets developed from detailed groundwater modeling. These comparisons illustrate the potential value of regional-scale analyses to supplement global hydrological models and GRACE analyses of groundwater depletion. Regional-scale analyses allow assessments of water stress that better account for scale effects, the dynamics of groundwater flow systems, the complexities of irrigated agricultural systems, and the laws, regulations, engineering, and socioeconomic factors that govern groundwater use. Strategic use of regional-scale models with global-scale analyses would greatly enhance knowledge of the global groundwater depletion problem.

Headaches: Reduce Stress to Prevent the Pain

MedlinePlus

... your ability to cope with stress. Lack of sleep puts your body under stress and may trigger the release of stress hormones, such as adrenaline and cortisol. Seek support. Talking things out with family or friends or allowing ...

Psychosocial workload and stress in the workers’ representative

PubMed Central

2012-01-01

Background Using a data set of works councils of trade union IG Metal, this paper investigates psychosocial stress and strain on this specific group in comparison to employees working in administration in general (leadership and non-leadership-role) and a national reference value. Methods For assessing psychosocial work factors on works councils within the sector represented by the trade union IG Metal in Germany, a research by using the German standard version of COPSOQ (Copenhagen Psychosocial Questionnaire) was performed. The instrument includes 87 single items forming 25 aspects of strain and stress. Results from the study group of works councils were compared to those from employees working in administration and to the general population mean (COPSOQ database). Statistical analysis included t-tests, analysis of variance and multiple comparisons of means. To be significant in terms of statistics, p<0.05 (two-tailed) and a minimum deviation of 5 or more points between groups′ mean values identify the relevant values. Results All in all, 309 works councils from a national survey of the German chemical and metalworking industries took part in the study. 113 were full-time works council members (exempted from the duty to perform their regular work), 196 were voluntary members (acting as employee representatives on an honorary basis alongside their normal duties). Comparison between works councils and employees working in administration (leadership roles (N=1810) and non-leadership roles (N=2970)) and for employees in general (N=35.000) showed unfavourable values for works councils for most scales. Significantly higher values indicating higher strain and stress were found for the scales: emotional demands, work-privacy conflict, role conflicts, mobbing, cognitive stress symptoms and burnout. Unfavourable results were obtained for the aspects: quality of leadership, social support, sense of community and general health. Favourable findings were found on the scales

The cognitive activation theory of stress.

PubMed

Ursin, Holger; Eriksen, Hege R

2004-06-01

This paper presents a cognitive activation theory of stress (CATS), with a formal system of systematic definitions. The term "stress" is used for four aspects of "stress", stress stimuli, stress experience, the non-specific, general stress response, and experience of the stress response. These four meanings may be measured separately. The stress response is a general alarm in a homeostatic system, producing general and unspecific neurophysiological activation from one level of arousal to more arousal. The stress response occurs whenever there is something missing, for instance a homeostatic imbalance, or a threat to homeostasis and life of the organism. Formally, the alarm occurs when there is a discrepancy between what should be and what is-between the value a variable should have (set value (SV)), and the real value (actual value (AV)) of the same variable. The stress response, therefore, is an essential and necessary physiological response. The unpleasantness of the alarm is no health threat. However, if sustained, the response may lead to illness and disease through established pathophysiological processes ("allostatic load"). The alarm elicits specific behaviors to cope with the situation. The level of alarm depends on expectancy of the outcome of stimuli and the specific responses available for coping. Psychological defense is defined as a distortion of stimulus expectancies. Response outcome expectancies are defined as positive, negative, or none, to the available responses. This offers formal definitions of coping, hopelessness, and helplessness that are easy to operationalize in man and in animals. It is an essential element of CATS that only when coping is defined as positive outcome expectancy does the concept predict relations to health and disease.

The predictive value of early maladaptive schemas in paranoid responses to social stress.

PubMed

Sundag, Johanna; Ascone, Leonie; Lincoln, Tania M

2018-01-01

Social stress and negatively valenced cognitive representations of the self (self-schemas) play an important role in the formation of delusions. However, it has not been investigated whether and which self-schemas explain paranoid responses to social stress. Building on the framework of schema theory, the aim of this study was thus to investigate whether more pronounced early maladaptive schemas (EMSs) were associated with increased paranoid ideation after a social stress induction in patients with persecutory delusions (PD). Patients with PD (n = 20) and healthy controls (n = 40) were assessed for EMSs with the Young Schema Questionnaire. They were then exposed to a social stress situation in which they were socially excluded in a Cyberball paradigm. Prior to and after the social stress induction, paranoid symptoms were assessed. Patients with PD responded with a stronger increase in paranoia and revealed a significantly higher EMS total score compared to the healthy controls. As expected, higher increases in paranoia following the social stress were accounted for by higher EMS total scores. Exploratory analyses showed that particularly the specific EMSs Defectiveness/Shame and Enmeshment/Undeveloped Self were associated with the increase in paranoia. EMSs are associated with stress-related symptom increases in patients with PD. It thus seems worthwhile to further investigate the relevance of specific schemas for paranoia. The findings also suggest that addressing EMSs in psychological treatment of patients with PD holds potential. Copyright © 2017 John Wiley & Sons, Ltd.

Aftershock decay, productivity, and stress rates in Hawaii: Indicators of temperature and stress from magma sources

USGS Publications Warehouse

Klein, Fred W.; Wright, Tom; Nakata, Jennifer

2006-01-01

We examined dozens of aftershock sequences in Hawaii in terms of Gutenberg-Richter and modified Omori law parameters. We studied p, the rate of aftershock decay; Ap, the aftershock productivity, defined as the observed divided by the expected number of aftershocks; and c, the time delay when aftershock rates begin to fall. We found that for earthquakes shallower than 20 km, p values >1.2 are near active magma centers. We associate this high decay rate with higher temperatures and faster stress relaxation near magma reservoirs. Deep earthquakes near Kilauea's inferred magma transport path show a range of p values, suggesting the absence of a large, deep magma reservoir. Aftershock productivity is >4.0 for flank earthquakes known to be triggered by intrusions but is normal (0.25 to 4.0) for isolated main shocks. We infer that continuing, post-main shock stress from the intrusion adds to the main shock's stress step and causes higher Ap. High Ap in other zones suggests less obvious intrusions and pulsing magma pressure near Kilauea's feeding conduit. We calculate stress rates and stress rate changes from pre-main shock and aftershock rates. Stress rate increased after many intrusions but decreased after large M7–8 earthquakes. Stress rates are highest in the seismically active volcano flanks and lowest in areas far from volcanic centers. We found sequences triggered by intrusions tend to have high Ap, high (>0.10 day) c values, a stress rate increase, and sometimes a peak in aftershock rate hours after the main shock. We interpret these values as indicating continuing intrusive stress after the main shock.

Prognostic value of myocardial ischemia and necrosis in depressed left ventricular function: a multicenter stress cardiac magnetic resonance registry.

PubMed

Husser, Oliver; Monmeneu, Jose V; Bonanad, Clara; Lopez-Lereu, Maria P; Nuñez, Julio; Bosch, Maria J; Garcia, Carlos; Sanchis, Juan; Chorro, Francisco J; Bodi, Vicente

2014-09-01

The incremental prognostic value of inducible myocardial ischemia over necrosis derived by stress cardiac magnetic resonance in depressed left ventricular function is unknown. We determined the prognostic value of necrosis and ischemia in patients with depressed left ventricular function referred for dipyridamole stress perfusion magnetic resonance. In a multicenter registry using stress magnetic resonance, the presence (≥ 2 segments) of late enhancement and perfusion defects and their association with major events (cardiac death and nonfatal infarction) was determined. In 391 patients, perfusion defect or late enhancement were present in 224 (57%) and 237 (61%). During follow-up (median, 96 weeks), 47 major events (12%) occurred: 25 cardiac deaths and 22 myocardial infarctions. Patients with major events displayed a larger extent of perfusion defects (6 segments vs 3 segments; P <.001) but not late enhancement (5 segments vs 3 segments; P =.1). Major event rate was significantly higher in the presence of perfusion defects (17% vs 5%; P =.0005) but not of late enhancement (14% vs 9%; P =.1). Patients were categorized into 4 groups: absence of perfusion defect and absence of late enhancement (n = 124), presence of late enhancement and absence of perfusion defect (n = 43), presence of perfusion defect and presence of late enhancement (n = 195), absence of late enhancement and presence of perfusion defect (n = 29). Event rate was 5%, 7%, 16%, and 24%, respectively (P for trend = .003). In a multivariate regression model, only perfusion defect (hazard ratio = 2.86; 95% confidence interval, 1.37-5.95]; P = .002) but not late enhancement (hazard ratio = 1.70; 95% confidence interval, 0.90-3.22; P =.105) predicted events. In depressed left ventricular function, the presence of inducible ischemia is the strongest predictor of major events. Copyright © 2014 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.

Simulation and in situ measurement of stress distribution in a polymer electrolyte membrane fuel cell stack

NASA Astrophysics Data System (ADS)

de la Cruz, Javier; Cano, Ulises; Romero, Tatiana

2016-10-01

A critical parameter for PEM fuel cell's electric contact is the nominal clamping pressure. Predicting the mechanical behavior of all components in a fuel cell stack is a very complex task due to the diversity of materials properties. Prior to the integration of a 3 kW PEMFC power plant, a numerical simulation was performed in order to obtain the mechanical stress distribution for two of the most pressure sensitive components of the stack: the membrane, and the graphite plates. The stress distribution of the above mentioned components was numerically simulated by finite element analysis and the stress magnitude for the membrane was confirmed using pressure films. Stress values were found within the elastic zone which guarantees mechanical integrity of fuel cell components. These low stress levels particularly for the membrane will allow prolonging the life and integrity of the fuel cell stack according to its design specifications.

32 CFR 564.58 - Determination of amount allowable.

Code of Federal Regulations, 2011 CFR

2011-07-01

... immediately prior to the accident or incident. Subject to the foregoing, the amount allowable is the cost... which it was immediately prior to the accident or incident. However, if as the result of the repairs... accident or incident, the difference in value will be added to the cost of repairs in determining the...

32 CFR 564.58 - Determination of amount allowable.

Code of Federal Regulations, 2010 CFR

2010-07-01

... immediately prior to the accident or incident. Subject to the foregoing, the amount allowable is the cost... which it was immediately prior to the accident or incident. However, if as the result of the repairs... accident or incident, the difference in value will be added to the cost of repairs in determining the...

32 CFR 564.58 - Determination of amount allowable.

Code of Federal Regulations, 2012 CFR

2012-07-01

... immediately prior to the accident or incident. Subject to the foregoing, the amount allowable is the cost... which it was immediately prior to the accident or incident. However, if as the result of the repairs... accident or incident, the difference in value will be added to the cost of repairs in determining the...

42 CFR 61.8 - Benefits: Stipends; dependency allowances; travel allowances; vacation.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false Benefits: Stipends; dependency allowances; travel...; dependency allowances; travel allowances; vacation. Individuals awarded regular fellowships shall be entitled...) Stipend. (b) Dependency allowances. (c) When authorized in advance, separate allowances for travel. Such...

42 CFR 61.8 - Benefits: Stipends; dependency allowances; travel allowances; vacation.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Benefits: Stipends; dependency allowances; travel...; dependency allowances; travel allowances; vacation. Individuals awarded regular fellowships shall be entitled...) Stipend. (b) Dependency allowances. (c) When authorized in advance, separate allowances for travel. Such...

42 CFR 61.8 - Benefits: Stipends; dependency allowances; travel allowances; vacation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Benefits: Stipends; dependency allowances; travel...; dependency allowances; travel allowances; vacation. Individuals awarded regular fellowships shall be entitled...) Stipend. (b) Dependency allowances. (c) When authorized in advance, separate allowances for travel. Such...

42 CFR 61.8 - Benefits: Stipends; dependency allowances; travel allowances; vacation.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Benefits: Stipends; dependency allowances; travel...; dependency allowances; travel allowances; vacation. Individuals awarded regular fellowships shall be entitled...) Stipend. (b) Dependency allowances. (c) When authorized in advance, separate allowances for travel. Such...

42 CFR 61.8 - Benefits: Stipends; dependency allowances; travel allowances; vacation.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false Benefits: Stipends; dependency allowances; travel...; dependency allowances; travel allowances; vacation. Individuals awarded regular fellowships shall be entitled...) Stipend. (b) Dependency allowances. (c) When authorized in advance, separate allowances for travel. Such...

Deriving allowable properties of lumber : a practical guide for interpretation of ASTM standards

Treesearch

Alan Bendtsen; William L. Galligan

1978-01-01

The ASTM standards for establishing clear wood mechanical properties and for deriving structural grades and related allowable properties for visually graded lumber can be confusing and difficult for the uninitiated to interpret. This report provides a practical guide to using these standards for individuals not familiar with their application. Sample stress...

Carbon Nanotube/Polymer Nanocomposites Flexible Stress and Strain Sensors

NASA Technical Reports Server (NTRS)

Kang, Jin Ho; Sauti, Godfrey; Park, Cheol; Scholl, Jonathan A.; Lowther, Sharon E.; Harrison, Joycelyn S.

2008-01-01

Conformable stress and strain sensors are required for monitoring the integrity of airframe structures as well as for sensing the mechanical stimuli in prosthetic arms. For this purpose, we have developed a series of piezoresistive single-wall carbon nanotube (SWCNT)/polymer nanocomposites. The electromechanical coupling of pressure with resistance changes in these nanocomposites is exceptionally greater than that of metallic piezoresistive materials. In fact, the piezoresistive stress coefficient (pi) of a SWCNT/polymer nanocomposite is approximately two orders of magnitude higher than that of a typical metallic piezoresistive. The piezoresistive stress coefficient is a function of the nanotube concentration wherein the maximum value occurs at a concentration just above the percolation threshold concentration (phi approx. 0.05 %). This response appears to originate from a change in intrinsic resistivity under compression/tension. A systematic study of the effect of the modulus of the polymer matrix on piezoresistivity allowed us to make flexible and conformable sensors for biomedical applications. The prototype haptic sensors using these nanocomposites are demonstrated. The piezocapacitive properties of SWCNT/polymer are also characterized by monitoring the capacitance change under pressure.

Influence of gender and stress on the volatile sulfur compounds and stress biomarkers production.

PubMed

Lima, P O; Calil, C M; Marcondes, F K

2013-05-01

Stress and menstrual cycle have been described as factors influencing bad breath, as they can alter oral homeostasis and contribute to the production of volatile sulfur compounds (VSC). Considering that the experimenter's and volunteer's gender may influence the volunteer's responses to stress, the aim of this work was to evaluate the influence of stress and gender on the production of VSC and salivary biomarkers. The experimental acute stress was induced by the Video-Recorded Stroop Color-Word Test (VRSCWT). The VSC, salivary proteins, and cardiovascular parameters were measured before and after VRSCWT. The VRSCWT induced significant increase in total VSC, hydrogen sulfide, and blood pressure values in men and women. Women presented higher values of both these compounds than men. The increase in systolic blood pressure was more pronounced when subjects were evaluated by an experimenter of the opposite gender. When women were evaluated by a member of the opposite gender, they showed significant increases in salivary alpha-amylase and cortisol compared with baseline values. Thus, the results showed that VRSCWT induced acute stress, which increased VSC production, and these effects were shown to be influenced by the gender. © 2012 John Wiley & Sons A/S.

Modulation of oxidative stress and subsequent induction of apoptosis and endoplasmic reticulum stress allows citral to decrease cancer cell proliferation.

PubMed

Kapur, Arvinder; Felder, Mildred; Fass, Lucas; Kaur, Justanjot; Czarnecki, Austin; Rathi, Kavya; Zeng, San; Osowski, Kathryn Kalady; Howell, Colin; Xiong, May P; Whelan, Rebecca J; Patankar, Manish S

2016-06-08

The monoterpenoid, citral, when delivered through PEG-b-PCL nanoparticles inhibits in vivo growth of 4T1 breast tumors. Here, we show that citral inhibits proliferation of multiple human cancer cell lines. In p53 expressing ECC-1 and OVCAR-3 but not in p53-deficient SKOV-3 cells, citral induces G1/S cell cycle arrest and apoptosis as determined by Annexin V staining and increased cleaved caspase3 and Bax and decreased Bcl-2. In SKOV-3 cells, citral induces the ER stress markers CHOP, GADD45, EDEM, ATF4, Hsp90, ATG5, and phospho-eIF2α. The molecular chaperone 4-phenylbutyric acid attenuates citral activity in SKOV-3 but not in ECC-1 and OVCAR-3 cells. In p53-expressing cells, citral increases phosphorylation of serine-15 of p53. Activation of p53 increases Bax, PUMA, and NOXA expression. Inhibition of p53 by pifithrin-α, attenuates citral-mediated apoptosis. Citral increases intracellular oxygen radicals and this leads to activation of p53. Inhibition of glutathione synthesis by L-buthionine sulfoxamine increases potency of citral. Pretreatment with N-acetylcysteine decreases phosphorylation of p53 in citral-treated ECC-1 and OVCAR-3. These results define a p53-dependent, and in the absence of p53, ER stress-dependent mode of action of citral. This study indicates that citral in PEG-b-PCL nanoparticle formulation should be considered for treatment of breast and other tumors.

Modulation of oxidative stress and subsequent induction of apoptosis and endoplasmic reticulum stress allows citral to decrease cancer cell proliferation

PubMed Central

Kapur, Arvinder; Felder, Mildred; Fass, Lucas; Kaur, Justanjot; Czarnecki, Austin; Rathi, Kavya; Zeng, San; Osowski, Kathryn Kalady; Howell, Colin; Xiong, May P.; Whelan, Rebecca J.; Patankar, Manish S.

2016-01-01

The monoterpenoid, citral, when delivered through PEG-b-PCL nanoparticles inhibits in vivo growth of 4T1 breast tumors. Here, we show that citral inhibits proliferation of multiple human cancer cell lines. In p53 expressing ECC-1 and OVCAR-3 but not in p53-deficient SKOV-3 cells, citral induces G1/S cell cycle arrest and apoptosis as determined by Annexin V staining and increased cleaved caspase3 and Bax and decreased Bcl-2. In SKOV-3 cells, citral induces the ER stress markers CHOP, GADD45, EDEM, ATF4, Hsp90, ATG5, and phospho-eIF2α. The molecular chaperone 4-phenylbutyric acid attenuates citral activity in SKOV-3 but not in ECC-1 and OVCAR-3 cells. In p53-expressing cells, citral increases phosphorylation of serine-15 of p53. Activation of p53 increases Bax, PUMA, and NOXA expression. Inhibition of p53 by pifithrin-α, attenuates citral-mediated apoptosis. Citral increases intracellular oxygen radicals and this leads to activation of p53. Inhibition of glutathione synthesis by L-buthionine sulfoxamine increases potency of citral. Pretreatment with N-acetylcysteine decreases phosphorylation of p53 in citral-treated ECC-1 and OVCAR-3. These results define a p53-dependent, and in the absence of p53, ER stress-dependent mode of action of citral. This study indicates that citral in PEG-b-PCL nanoparticle formulation should be considered for treatment of breast and other tumors. PMID:27270209

[Exercise stress test and dobutamine stress echocardiography for the prognostic stratification after uncomplicated acute myocardial infarction].

PubMed

Vitiello, Nicola; Cirillo, Raffaele; Granato, Luigi; Coppola, Vincenzo; di Palma, Francesco

2007-05-01

Exercise stress test and dobutamine stress echocardiography are usually performed early after an uncomplicated acute myocardial infarction in the prognostic stratification of patients to define the optimal diagnostic and therapeutic procedure. The aim of this study was to evaluate if the association of an imaging test could increase exercise test capability to identify patients with residual ischemia and patients at high risk of events in the follow-up. Four hundred and forty-two consecutive patients underwent exercise stress testing and dobutamine stress echocardiography before discharge and subsequently coronary angiography within 30 days. In case of submaximal negative result at the exercise test, this was repeated 20 days after discharge. The follow-up lasted 26.8 +/- 9 months. The endpoints were death, reinfarction, and unstable angina requiring hospitalization or revascularization intervention. Both tests and their association showed a higher sensitivity in males; in females dobutamine stress echocardiography had a higher specificity. In females, the addition of dobutamine stress echocardiography increased either the negative or the positive prognostic values of exercise stress test by 31% and 5.6%, respectively. In males, the negative prognostic value increased by 15.5%, whereas the positive prognostic value decreased by 12%. A low exercise capability (<6 METs) showed an event predictive value independent of test results and any other variables. The event-free survival curves correlated with exercise capability differed shortly after the first months both in males and females. These results suggest different stratification procedures with regard to gender: in males, the exercise stress test might be sufficient at discharge, to be repeated 20 days later, if submaximal negative. In females, it seems to be useful to associate an imaging test at discharge. In any case, the exercise stress test remains the main step in the stratification procedure also for its

Normal Values of Tissue-Muscle Perfusion Indexes of Lower Limbs Obtained with a Scintigraphic Method.

PubMed

Manevska, Nevena; Stojanoski, Sinisa; Pop Gjorceva, Daniela; Todorovska, Lidija; Miladinova, Daniela; Zafirova, Beti

2017-09-01

Introduction Muscle perfusion is a physiologic process that can undergo quantitative assessment and thus define the range of normal values of perfusion indexes and perfusion reserve. The investigation of the microcirculation has a crucial role in determining the muscle perfusion. Materials and method The study included 30 examinees, 24-74 years of age, without a history of confirmed peripheral artery disease and all had normal findings on Doppler ultrasonography and pedo-brachial index of lower extremity (PBI). 99mTc-MIBI tissue muscle perfusion scintigraphy of lower limbs evaluates tissue perfusion in resting condition "rest study" and after workload "stress study", through quantitative parameters: Inter-extremity index (for both studies), left thigh/right thigh (LT/RT) left calf/right calf (LC/RC) and perfusion reserve (PR) for both thighs and calves. Results In our investigated group we assessed the normal values of quantitative parameters of perfusion indexes. Indexes ranged for LT/RT in rest study 0.91-1.05, in stress study 0.92-1.04. LC/RC in rest 0.93-1.07 and in stress study 0.93-1.09. The examinees older than 50 years had insignificantly lower perfusion reserve of these parameters compared with those younger than 50, LC (p=0.98), and RC (p=0.6). Conclusion This non-invasive scintigraphic method allows in individuals without peripheral artery disease to determine the range of normal values of muscle perfusion at rest and stress condition and to clinically implement them in evaluation of patients with peripheral artery disease for differentiating patients with normal from those with impaired lower limbs circulation.

A mechanical model of metatarsal stress fracture during distance running.

PubMed

Gross, T S; Bunch, R P

1989-01-01

A model of metatarsal mechanics has been proposed as a link between the high incidence of second and third metatarsal stress fractures and the large stresses measured beneath the second and third metatarsal heads during distance running. Eight discrete piezoelectric vertical stress transducers were used to record the forefoot stresses of 21 male distance runners. Based upon load bearing area estimates derived from footprints, plantar forces were estimated. Highest force was estimated beneath the second and first metatarsal head (341.1 N and 279.1 N, respectively). Considering the toe as a hinged cantilever and the metatarsal as a proximally attached rigid cantilever allowed estimation of metatarsal midshaft bending strain, shear, and axial forces. Bending strain was estimated to be greatest in the second metatarsal (6662 mu epsilon), a value 6.9 times greater than estimated first metatarsal strain. Predicted third, fourth, and fifth metatarsal strains ranged between 4832 and 5241 mu epsilon. Shear force estimates were also greatest in the second metatarsal (203.0 N). Axial forces were highest in the first metatarsal (593.2 N) due to large hallux forces in relationship to the remaining toes. Although a first order model, these data highlight the structural demands placed upon the second metatarsal, a location of high metatarsal stress fracture incidence during distance running.

Earthquake stress drops, ambient tectonic stresses and stresses that drive plate motions

USGS Publications Warehouse

Hanks, T.C.

1977-01-01

A variety of geophysical observations suggests that the upper portion of the lithosphere, herein referred to as the elastic plate, has long-term material properties and frictional strength significantly greater than the lower lithosphere. If the average frictional stress along the non-ridge margin of the elastic plate is of the order of a kilobar, as suggested by the many observations of the frictional strength of rocks at mid-crustal conditions of pressure and temperature, the only viable mechanism for driving the motion of the elastic plate is a basal shear stress of several tens of bars. Kilobars of tectonic stress are then an ambient, steady condition of the earth's crust and uppermost mantle. The approximate equality of the basal shear stress and the average crustal earthquake stress drop, the localization of strain release for major plate margin earthquakes, and the rough equivalence of plate margin slip rates and gross plate motion rates suggest that the stress drops of major plate margin earthquakes are controlled by the elastic release of the basal shear stress in the vicinity of the plate margin, despite the existence of kilobars of tectonic stress existing across vertical planes parallel to the plate margin. If the stress differences available to be released at the time of faulting are distributed in a random, white fasbion with a mean-square value determined by the average earthquake stress drop, the frequency of occurrence of constant stress drop earthquakes will be proportional to reciprocal faulting area, in accordance with empirically known frequency of occurrence statistics. ?? 1977 Birkha??user Verlag.

Effect of far-field stresses and residual stresses incorporation in predicting fracture toughness of carbon nanotube reinforced yttria stabilized zirconia

NASA Astrophysics Data System (ADS)

Mahato, Neelima; Nisar, Ambreen; Mohapatra, Pratyasha; Rawat, Siddharth; Ariharan, S.; Balani, Kantesh

2017-10-01

Yttria-stabilized zirconia (YSZ) is a potential thermal insulating ceramic for high temperature applications (>1000 °C). YSZ reinforced with multi-walled carbon nanotubes (MWNTs) was processed via spark plasma sintering to produce dense, crack-free homogeneous sample and avoid any degradation of MWNTs when sintered using conventional routes. Despite porosity, the addition of MWNT has a profound effect in improving the damage tolerance of YSZ by allowing the retention of tetragonal phase. However, at some instances, the crack lengths in the MWNT reinforced YSZ matrices have been found to be longer than the standalone counterparts. Therefore, it becomes inappropriate to apply Anstis equation to calculate fracture toughness values. In this regard, a combined analytical cum numerical method is used to estimate the theoretical fracture toughness and quantitatively analyze the mechanics of matrix cracking in the reinforced composite matrices incorporating the effects of various factors (such as far-field stresses, volume fraction of MWNTs, change in the modulus and Poisson's ratio values along with the increase in porosity, and bridging and phase transformation mechanism) affecting the fracture toughness of YSZ-MWNT composites. The results suggest that the incorporation of far-field stresses cannot be ignored in estimating the theoretical fracture toughness of YSZ-MWNT composites.

Calculation of intrinsic stresses in the diamond-like coatings produced by plasma ion deposition in modes of DC and pulse bias potentials

NASA Astrophysics Data System (ADS)

Kalinichenko, A. A.; Perepelkin, S. S.; Strel'nitskij, V. E.

2015-04-01

The formula derivation for calculation of intrinsic stress in diamond-like coatings deposited from the ion flux in modes of continuous and pulsed potentials in view of process of defects formation is given. The criterion of applicability of obtained formula allowing to determine critical parameters of the pulsed potential mode is suggested. Results of calculation of stresses in diamond-like coatings at deposition of low-energy ions C+ from filtered vacuum arc plasma are adduced. The influence of the bias potential, repetition frequency and pulse duration, on the value of intrinsic stress is discussed. Qualitative agreement of calculated stress and experimental data is stated. The important role of deposition temperature in control of intrinsic stress in deposited coating is noted.

Statistics of Static Stress Earthquake Triggering

NASA Astrophysics Data System (ADS)

Nandan, S.; Ouillon, G.; Woessner, J.; Sornette, D.; Wiemer, S.

2014-12-01

A likely source of earthquake clustering is static and/or dynamic stresses transferred by individual events. Previous attempts to quantify the role of static stress generally considered only the stress changes caused by large events, and often discarded data uncertainties. We test the static stress change hypothesis empirically by considering all events of magnitude M≥ 2.1 and the uncertainties in location and focal mechanism in the focal mechanism catalog for Southern California between 1981 and 2010 (Yang et al., 2011). We quantify: How the waiting time between earthquakes (1) relates to the Coulomb stress change (2) induced by event Ei at the location of Ej; How significant is the Coulomb Index (CI), fraction of source-receiver pairs with positive ΔCFS interactions, conditioned on time and amplitude of ΔCFS, compared to a mean-field CI derived from the time-independent structure of the fault network. We approximate the waiting time distributions empirically by (3), which respectively consists of triggering and background rate components, tapered by an exponential term to model the finiteness of the catalog. We observe that K/(Bc^p ) (the ratio of the triggering to the background rates at t=0), the exponent p, and the Maxwell time τ all increase with |ΔCFS| and are significantly larger for positive than for negative ΔCFS's. τ varies between ~90 days and ~150 days (approximately 0.3 decades over 6 decades of variation in stress). It defines the time beyond which the memory of stress is overprinted by occurrence of other events. The CI values become significant above a threshold |ΔCFS|. The mean-field CI is 52%, while the maximum observed CI value is ~60%. Correcting for the focal plane ambiguity, those values become respectively ~55% and ~72%. Lastly, the CI values decrease with the waiting time and converge to the mean-field CI value. The increase of p-value and K/(Bc^p ) with |ΔCFS| contradicts the prediction of stress shadow regions where seismicity

Urinary excretion values in 2-day food-deprived, unrestrained chimpanzees.

NASA Technical Reports Server (NTRS)

Mcnew, J. J.; Sabbot, I. M.; Hoshizaki, T.; Mandell, A. J.; Spooner, C. E.; Marcus, I.; Adey, W. R.

1972-01-01

A study was conducted to determine the baseline 24-hr urinary excretion values in the young, unrestrained chimpanzee, and also changes in urinary values, if any, induced by the two-day food deprivation stress. Urine was analyzed for volume, osmolarity, creatinine, creatine, urea nitrogen, 17-hydroxycorticosteroids (17-OHCS), 3-methoxy-4-hydroxymandelic acid (VMA), calcium, and inorganic phosphorus. Significant increases due to food deprivation stress were observed for volume, creatine, urea nitrogen, 17-OHCS, VMA, and phosphorus values, with significant decreases in osmolarity and calcium. All values approached normal levels by the second poststress day. No significant changes were observed in creatinine. A comparison is drawn between human and chimpanzee adaptation to stress.

Effect of Coulomb stress on the Gutenberg-Richter law

NASA Astrophysics Data System (ADS)

Navas-Portella, V.; Corral, A.; Jimenez, A.

2017-12-01

Coulomb stress theory has been used for years in seismology to understand how earthquakes trigger each other. Whenever an earthquake occurs, the stress field changes in its neighbourhood, with places with positive values brought closer to failure, whereas negative values distance away that location from failure. Earthquake models that relate rate changes and Coulomb stress after a main event, such as the rate-and-state model, assume negative and positive stress values affect rate changes according to the same functional form. As a first order approximation, under uniform background seismicity before the main event, different values of the b-exponent in the Gutenberg-Richter law would indicate different behaviour for positive and negative stress. In this work, we study the Gutenberg-Richter law in the aftershock sequence of the Landers earthquake (California, 1992, MW=7.3). By using a statistically based fitting method, we discuss whether the sign of Coulomb stresses and the distance to the fault have a significant effect on the value of the b-exponent.

Multi-layered bird beaks: a finite-element approach towards the role of keratin in stress dissipation

PubMed Central

Soons, Joris; Herrel, Anthony; Genbrugge, Annelies; Adriaens, Dominique; Aerts, Peter; Dirckx, Joris

2012-01-01

Bird beaks are layered structures, which contain a bony core and an outer keratin layer. The elastic moduli of this bone and keratin were obtained in a previous study. However, the mechanical role and interaction of both materials in stress dissipation during seed crushing remain unknown. In this paper, a multi-layered finite-element (FE) model of the Java finch's upper beak (Padda oryzivora) is established. Validation measurements are conducted using in vivo bite forces and by comparing the displacements with those obtained by digital speckle pattern interferometry. Next, the Young modulus of bone and keratin in this FE model was optimized in order to obtain the smallest peak von Mises stress in the upper beak. To do so, we created a surrogate model, which also allows us to study the impact of changing material properties of both tissues on the peak stresses. The theoretically best values for both moduli in the Java finch are retrieved and correspond well with previous experimentally obtained values, suggesting that material properties are tuned to the mechanical demands imposed during seed crushing. PMID:22337628

Therapeutic Ultrasound in Navicular Stress Injuries in Elite Track and Field Athletes.

PubMed

Malliaropoulos, Nikolaos; Alaseirlis, Dimosthenis; Konstantinidis, George; Papalada, Agapi; Tsifountoudis, Ioannis; Petras, Kosmas; Maffulli, Nicola

2017-05-01

To ascertain whether therapeutic ultrasound (TUS) can be used to assess the progression of conservative management in navicular stress injuries. This is a prospective, clinical case series. Level of evidence IV. All participants were examined and followed up in a private Sports Injury Clinic. Ten elite track and field athletes with severe dorsal midfoot pain over the navicular bone participated in this study. All patients underwent both TUS and magnetic resonance imaging (MRI) evaluation. The painful threshold of TUS on initial evaluation was a mean of 0.707 ± 149 W/cm, and MRI detected a navicular stress injury in all patients. The athletes received conservative treatment and underwent sequential TUS evaluations at 4, 8, 12 and 16 weeks. Therapeutic ultrasound pain threshold values were recorded, and the patients were additionally asked to grade local tenderness on a Visual Analogue Scale. Time to return to play was also recorded. The level of pain produced by the application of TUS on a navicular stress fracture seemed to correlate well with Visual Analogue Scale scores and the grade of fracture demonstrated on MRI. The initial low TUS painful mean value increased to a normal mean value of 1.97 ± 0.067 W/cm by 16 weeks. When clinical and TUS findings had returned to normal, the patients were allowed to return to sports activities, with no recurrences experienced during the study period. The production of pain associated with the application of TUS on a navicular stress fracture is a safe and reproducible method of monitoring the resolution of these fractures. We have used it successfully in making return-to-play decisions for elite level track and field athletes.

Stress Management in Correctional Recreation.

ERIC Educational Resources Information Center

Card, Jaclyn A.

Current economic conditions have created additional sources of stress in the correctional setting. Often, recreation professionals employed in these settings also add to inmate stress. One of the major factors limiting stress management in correctional settings is a lack of understanding of the value, importance, and perceived freedom, of leisure.…

Stressed out symbiotes: hypotheses for the influence of abiotic stress on arbuscular mycorrhizal fungi.

PubMed

Millar, Niall S; Bennett, Alison E

2016-11-01

Abiotic stress is a widespread threat to both plant and soil communities. Arbuscular mycorrhizal (AM) fungi can alleviate effects of abiotic stress by improving host plant stress tolerance, but the direct effects of abiotic stress on AM fungi are less well understood. We propose two hypotheses predicting how AM fungi will respond to abiotic stress. The stress exclusion hypothesis predicts that AM fungal abundance and diversity will decrease with persistent abiotic stress. The mycorrhizal stress adaptation hypothesis predicts that AM fungi will evolve in response to abiotic stress to maintain their fitness. We conclude that abiotic stress can have effects on AM fungi independent of the effects on the host plant. AM fungal communities will change in composition in response to abiotic stress, which may mean the loss of important individual species. This could alter feedbacks to the plant community and beyond. AM fungi will adapt to abiotic stress independent of their host plant. The adaptation of AM fungi to abiotic stress should allow the maintenance of the plant-AM fungal mutualism in the face of changing climates.

The Impact of Racial Identity, Ethnic Identity, Asian Values, and Race-Related Stress on Asian Americans and Asian International College Students' Psychological Well-Being

ERIC Educational Resources Information Center

Iwamoto, Derek Kenji; Liu, William Ming

2010-01-01

The present study investigated the direct and moderating effects of racial identity, ethnic identity, Asian values, and race-related stress on positive psychological well-being among 402 Asian American and Asian international college students. Results revealed that the racial identity statuses Internalization, Immersion-Emersion, Dissonance, Asian…

A Stress-Coping Model of Mental Illness Stigma: I. Predictors of Cognitive Stress Appraisal

PubMed Central

Rüsch, Nicolas; Corrigan, Patrick W.; Wassel, Abigail; Michaels, Patrick; Olschewski, Manfred; Wilkniss, Sandra; Batia, Karen

2009-01-01

Stigma can be a major stressor for individuals with schizophrenia and other mental illnesses. It is unclear, however, why some stigmatized individuals appraise stigma as more stressful, while others feel they can cope with the potential harm posed by public prejudice. We tested the hypothesis that the level of perceived public stigma and personal factors such as rejection sensitivity, perceived legitimacy of discrimination and ingroup perceptions (group value; group identification; entitativity, or the perception of the ingroup of people with mental illness as a coherent unit) predict the cognitive appraisal of stigma as a stressor. Stigma stress appraisal refers to perceived stigma-related harm exceeding perceived coping resources. Stress appraisal, stress predictors and social cue recognition were assessed in 85 people with schizophrenia, schizoaffective or affective disorders. Stress appraisal did not differ between diagnostic subgroups, but was positively correlated with rejection sensitivity. Higher levels of perceived societal stigma and holding the group of people with mental illness in low regard (low group value) independently predicted high stigma stress appraisal. These predictors remained significant after controlling for social cognitive deficits, depressive symptoms and diagnosis. Our findings support the model that public and personal factors predict stigma stress appraisal among people with mental illness, independent of diagnosis and clinical symptoms. Interventions that aim to reduce the impact of stigma on people with mental illness could focus on variables such as rejection sensitivity, a personal vulnerability factor, low group value and the cognitive appraisal of stigma as a stressor. PMID:19269140

Analysis of stress-induced oval fractures in a borehole at Deep Sea Drilling Project Site 504, eastern equatorial Pacific

USGS Publications Warehouse

Morin, R.H.; Flamand, R.

1999-01-01

Deep Sea Drilling Project (DSDP) Hole 504B is located in the eastern equatorial Pacific Ocean and extends to a total depth of 2111 m beneath the seafloor (mbsf). Several acoustic televiewer logs have been obtained in this well during successive stages of drilling, and the resulting digital images have revealed numerous oval-shaped fractures seemingly etched into the borehole wall. A theoretical examination of these stress-induced features identifies a unique and ephemeral set of stress distributions and magnitudes that are necessary for their production. Consequently, the ovals provide a basis for quantifying the magnitudes and orientations of the maximum and minimum horizontal principal stresses, SH and Sh, at this site. Vertical, truncated breakouts and horizontal tensile fractures define the spatial boundaries of the ovals. Explicit criteria for their occurrence are combined with estimates for various physical properties of the rock to yield a range of possible values for the horizontal principal stresses. The conspicuous oval geometry is completed by a curved fracture that joins the vertical and horizontal components. Its degree of curvature is delineated by the modified Griffith failure criterion and is directly related to the principal stress difference (SH - Sh). Matching a series of type curves corresponding to specific values for (SH - Sh) with the actual undistorted well bore images allows the magnitude of the stress difference to be further constrained. With a value for (SH - Sh) of 45 ?? 5 MPa the individual magnitudes of SH and Sh are determined more precisely. Final estimates for the horizontal principal stresses in DSDP Hole 504B at a depth of 1200 mbsf are 141 MPa ??? SH ??? 149 MPa and 91 MPa ??? Sh ??? 109 MPa. Stress magnitudes derived from this approach rely heavily upon the values of a variety of physical properties, and complementary laboratory measurements performed on relevant rock samples provide critical information. Uncertainties in

Remote sensing of drought and salinity stressed turfgrass

NASA Astrophysics Data System (ADS)

Ikemura, Yoshiaki

The ability to detect early signs of stress in turfgrass stands using a rapid, inexpensive, and nondestructive method would be a valuable management tool. Studies were conducted to determine if digital image analysis and spectroradiometric readings obtained from drought- and salinity-stressed turfgrasses accurately reflected the varying degrees of stress and correlated strongly with visual ratings, relative water content (RWC) and leaf osmolality, standard methods for measuring stress in plants. Greenhouse drought and salinity experiments were conducted on hybrid bluegrass [Poa arachnifera (Torn.) x pratensis (L.)] cv. Reveille and bermudagrass [Cynodon dactylon (L.)] cv. Princess 77. Increasing drought and salinity stress led to decreased RWC, increased leaf osmolality, and decreased visual ratings for both species. Percent green cover and hue values obtained from digital image analysis, and Normalized Difference Vegetation Index (NDVI), calculated from spectroradiometric readings, were moderately to highly correlated with visual ratings, RWC, and leaf osmolality. Similarly, in a field validation study conducted on hybrid bluegrass, spectral reflectance ratios were moderately to highly correlated with visual ratings. In addition, percent green cover obtained from digital image analysis was strongly correlated with most of the spectral ratios, particularly the ratio of fluorescence peaks (r = -0.88 to -0.99), modified triangular vegetation index (MTVI) (r = 0.82 to 0.98), and NDVI (r = 0.84 to 0.99), suggesting that spectral reflectance and digital image analysis are equally effective at detecting changes in color brought on by stress. The two methods differed in their ability to distinguish between drought salinity stress. Hue values obtained from digital image analysis responded differently to increasing drought stress than to increasing salinity stress. Whereas the onset of drought stress was reflected by increased hue values followed by a decrease in values as

Elbow stress indices using finite element analysis

NASA Astrophysics Data System (ADS)

Yu, Lixin

Section III of the ASME Boiler and Pressure Vessel Code (the Code) specifies rules for the design of nuclear power plant components. NB-3600 of the Code presents a simplified design method using stress indices---Scalar Coefficients used the modify straight pipe stress equations so that they can be applied to elbows, tees and other piping components. The stress indices of piping components are allowed to be determined both analytically and experimentally. This study concentrates on the determination of B2 stress indices for elbow components using finite element analysis (FEA). First, the previous theoretical, numerical and experimental investigations on elbow behavior were comprehensively reviewed, as was the philosophy behind the use of stress indices. The areas of further research was defined. Then, a comprehensive investigation was carried out to determine how the finite element method should be used to correctly simulate an elbow's structural behavior. This investigation included choice of element type, convergence of mesh density, use of boundary restraint and a reconciliation study between FEA and laboratory experiments or other theoretical formulations in both elastic and elasto-plastic domain. Results from different computer programs were also compared. Reasonably good reconciliation was obtained. Appendix II of the Code describes the experimental method to determine B2 stress indices based on load-deflection curves. This procedure was used to compute the B2 stress indices for various loading modes on one particular elbow configuration. The B2 stress indices thus determined were found to be about half of the value calculated from the Code equation. Then the effect on B2 stress indices of those factors such as internal pressure and flange attachments were studied. Finally, the investigation was extended to other configurations of elbow components. A parametric study was conducted on different elbow sizes and schedules. Regression analysis was then used to

Evolution of tensile design stresses for lumber

Treesearch

William L. Galligan; C. C. Gerhards; R. L. Ethington

1979-01-01

Until approximately 1965, allowable design stresses for lumber in tension were taken as equal to those assigned for bending. As interest in tensile properties increased, testing machines were designed specifically to stress lumber in tension. Research results that accumulated on tensile tests of full-size lumber suggested lower design stresses for tension than for...

30 CFR 206.179 - What general requirements regarding processing allowances apply to me?

Code of Federal Regulations, 2010 CFR

2010-07-01

... for each gas plant product and processing plant relationship. Natural gas liquids are considered as... THE INTERIOR MINERALS REVENUE MANAGEMENT PRODUCT VALUATION Indian Gas Processing Allowances § 206.179 What general requirements regarding processing allowances apply to me? (a) When you value any gas plant...

Exploring nursing staffs communication in stressful and non-stressful situations.

PubMed

André, Beate; Frigstad, Sigrun A; Nøst, Torunn H; Sjøvold, Endre

2016-03-01

To explore the factors that characterise the work environment, focusing on communication among nurses in stressful and non-stressful situations. Nursing is often described as a stressful occupation. Implementation of change may be an additional stress factor. Nurses and assistant nurses completed a questionnaire from two different perspectives, 'communication in non-stressful situations' and 'communication under stress'. The Systematising Person-Group Relations method was used to gather and analyse the data. When the two perspectives, 'communication in non-stressful situations' and 'communication under stress', were compared, there were significant differences in 8 of the 12 factors. The stressful situations were characterised by low values in task orientation, caring, criticism, loyalty, acceptance, engagement and empathy; only the factor creativity had higher scores. The stressful situations were characterised by creative and spontaneous behaviour, not by task orientation and engagement, indicating a potential patient safety risk. There is a need to help health-care workers develop more mature analytical and task-oriented behaviours related to both independent work and collaboration in stressful situations. Nursing leadership and organisation must focus on healthy work environments to promote engaged communication in stressful situations, ultimately increasing patient safety. © 2015 The Authors. Journal of Nursing Management Published by John Wiley & Sons Ltd.

Deriving the suction stress of unsaturated soils from water retention curve, based on wetted surface area in pores

NASA Astrophysics Data System (ADS)

Greco, Roberto; Gargano, Rudy

2016-04-01

The evaluation of suction stress in unsaturated soils has important implications in several practical applications. Suction stress affects soil aggregate stability and soil erosion. Furthermore, the equilibrium of shallow unsaturated soil deposits along steep slopes is often possible only thanks to the contribution of suction to soil effective stress. Experimental evidence, as well as theoretical arguments, shows that suction stress is a nonlinear function of matric suction. The relationship expressing the dependence of suction stress on soil matric suction is usually indicated as Soil Stress Characteristic Curve (SSCC). In this study, a novel equation for the evaluation of the suction stress of an unsaturated soil is proposed, assuming that the exchange of stress between soil water and solid particles occurs only through the part of the surface of the solid particles which is in direct contact with water. The proposed equation, based only upon geometric considerations related to soil pore-size distribution, allows to easily derive the SSCC from the water retention curve (SWRC), with the assignment of two additional parameters. The first parameter, representing the projection of the external surface area of the soil over a generic plane surface, can be reasonably estimated from the residual water content of the soil. The second parameter, indicated as H0, is the water potential, below which adsorption significantly contributes to water retention. For the experimental verification of the proposed approach such a parameter is considered as a fitting parameter. The proposed equation is applied to the interpretation of suction stress experimental data, taken from the literature, spanning over a wide range of soil textures. The obtained results show that in all cases the proposed relationships closely reproduces the experimental data, performing better than other currently used expressions. The obtained results also show that the adopted values of the parameter H0

Characterizing shallow secondary clarifier performance where conventional flux theory over-estimates allowable solids loading rate.

PubMed

Daigger, Glen T; Siczka, John S; Smith, Thomas F; Frank, David A; McCorquodale, J A

The performance characteristics of relatively shallow (3.3 and 3.7 m sidewater depth in 30.5 m diameter) activated sludge secondary clarifiers were extensively evaluated during a 2-year testing program at the City of Akron Water Reclamation Facility (WRF), Ohio, USA. Testing included hydraulic and solids loading stress tests, and measurement of sludge characteristics (zone settling velocity (ZSV), dispersed and flocculated total suspended solids), and the results were used to calibrate computational fluid dynamic (CFD) models of the various clarifiers tested. The results demonstrated that good performance could be sustained at surface overflow rates in excess of 3 m/h, as long as the clarifier influent mixed liquor suspended solids (MLSS) concentration was controlled to below critical values. The limiting solids loading rate (SLR) was significantly lower than the value predicted by conventional solids flux analysis based on the measured ZSV/MLSS relationship. CFD analysis suggested that this resulted because mixed liquor entering the clarifier was being directed into the settled sludge blanket, diluting it and also creating a 'thin' concentration sludge blanket that overlays the thicker concentration sludge blanket typically expected. These results indicate the need to determine the allowable SLR for shallow clarifiers using approaches other than traditional solids flux analysis. A combination of actual testing and CFD analyses are demonstrated here to be effective in doing so.

Differentiating anticipatory from reactive cortisol responses to psychosocial stress.

PubMed

Engert, Veronika; Efanov, Simona I; Duchesne, Annie; Vogel, Susanne; Corbo, Vincent; Pruessner, Jens C

2013-08-01

Most psychosocial stress studies assess the overall cortisol response without further identifying the temporal dynamics within hormone levels. It has been shown, however, that the amplitude of anticipatory cortisol stress levels has a unique predictive value for psychological health. So far, no "best practice" in how to investigate the anticipatory cortisol stress response has emerged. The goal of the current research was to develop a protocol that would allow for a sensitive and easy-to-implement laboratory-based investigation into anticipatory cortisol stress levels. We initially tested 26 healthy men in either an anticipation- or stress-only condition of the Trier Social Stress Test (TSST) to map the distinct timelines of anticipatory and reactive cortisol release profiles (study 1). Subsequently, we administered the TSST to 50 healthy men such that the cortisol responses to anticipatory and reactive stress components could be dissociated (study 2). In both studies we sampled saliva cortisol at high frequency (at baseline, during 10min of anticipation and during and after 10min of acute stress) and the current mood state pre- and post-stress. We found anticipatory responder rates of 20% and 40%, with peak anticipatory cortisol levels between 14 and 20min after onset of anticipation. Visible changes in reactive cortisol levels occurred only after the termination of the acute stressor. We conclude that the best practice to detect a maximum number of anticipatory responders in the TSST would be to extend the anticipation phase to 15min. In doing so, the anticipatory cortisol peak could be captured at a time-point of the actual stressor that is uninfluenced by reactive cortisol levels. Overall, we could reveal several features of anticipatory responders. Most importantly, there was a positive correlation between anticipatory and reactive stress responses. There was no association between anticipatory cortisol and alpha-amylase as well as subjective

Q2Stress: A database for multiple cues to stress assignment in Italian.

PubMed

Spinelli, Giacomo; Sulpizio, Simone; Burani, Cristina

2017-12-01

In languages where the position of lexical stress within a word is not predictable from print, readers rely on distributional information extracted from the lexicon in order to assign stress. Lexical databases are thus especially important for researchers willing to address stress assignment in those languages. Here we present Q2Stress, a new database aimed to fill the lack of such a resource for Italian. Q2Stress includes multiple cues readers may use in assigning stress, such as type and token frequency of stress patterns as well as their distribution with respect to number of syllables, grammatical category, word beginnings, word endings, and consonant-vowel structures. Furthermore, for the first time, data for both adults and children are available. Q2Stress may help researchers to answer empirical as well as theoretical questions about stress assignment and stress-related issues, and more in general, to explore the orthography-to-phonology relation in reading. Q2Stress is designed as a user-friendly resource, as it comes with scripts allowing researchers to explore and select their own stimuli according to several criteria as well as summary tables for overall data analysis.

Does the prognostic value of dobutamine stress echocardiography differ among different age groups?

PubMed

Bernheim, Alain M; Kittipovanonth, Maytinee; Takahashi, Paul Y; Gharacholou, S Michael; Scott, Christopher G; Pellikka, Patricia A

2011-04-01

Age is associated with reduced exercise capacity and greater prevalence of coronary artery disease. Whether the prognostic information obtained from dobutamine stress echocardiography (DSE), a stress test commonly used for patients unable to perform an exercise test, provides differential information based on age is not well known. We studied 6,655 consecutive patients referred for DSE. Patients were divided into 3 age groups: (1) <60 years (n = 1,389), (2) 60 to 74 years (n = 2,978), and (3) ≥75 years (n = 2,288). Mean follow-up was 5.5 ± 2.8 years. End points included all-cause mortality and cardiac events, including myocardial infarction and late (>3 months) coronary revascularization. Peak stress wall motion score index was an independent predictor of cardiac events in all age groups (<60 years: hazard ratio [HR] 1.14, P = .02; 60-74 years: HR 1.70, P < .0001; ≥75 years: HR 1.10, P = .006). In patients ≥75 years, peak wall motion score index (HR 1.10, P < .0001) and abnormal left ventricular end-systolic volume response (HR 1.25, P = .03) were independent predictors of death. In patients aged 60 to 74 years, abnormal left ventricular end-systolic volume response (HR 1.43, P = .0003) was independently related to death, whereas in patients <60 years, the echocardiographic data assessed during stress were not a predictor. Dobutamine stress echocardiography provided independent information predictive of cardiac events among all age groups and death in patients ≥60 years. However, among patients <60 years, stress-induced echocardiographic abnormalities were not independently associated with mortality. Comorbidities, which have precluded exercise testing, may be most relevant in predicting mortality in patients <60 years undergoing DSE. Copyright © 2011 Mosby, Inc. All rights reserved.

Value of lateral blood pool imaging in patients with suspected stress fractures of the tibia.

PubMed

Mohan, Hosahalli K; Clarke, Susan E M; Centenara, Martin; Lucarelli, Amanda; Baron, Daniel; Fogelman, Ignac

2011-03-01

To critically evaluate the use of lateral blood pool imaging in athletes with lower limb pain and with a clinical suspicion of stress fracture. Two experienced nuclear medicine physicians evaluated 3-phase bone scans using 99mTc-methylene diphosphonate performed in 50 consecutive patients referred from a specialist sports injury clinic for suspected tibial stress fracture. The vascularity to the tibia as seen on the blood pool (second phase) images in the anterior/posterior views was compared with the lateral/medial view assessments. Stress fractures were presumed to be present when on the delayed images (third phase) there was a focal or fusiform area of increased tracer uptake involving the tibial cortex. Shin splints which are a recognized cause of lower limb pain in athletes mimicking stress fracture were diagnosed if increased tracer uptake was seen extending along the posterior tibial surface with no significant focal or fusiform area of uptake within this. Inter-reviewer agreement for the assessment of vascularity was also assessed using Cohen's Kappa scores. Twenty-four stress fractures in 24 patients and 66 shin splints in 40 patients were diagnosed. In 18 patients stress fracture and shin splints coexisted. In 10 patients no tibial pathology was identified. Of the 24 patients diagnosed with stress fractures, lateral/medial blood pool imaging was superior in the assessment of blood pool activity (P < 0.001) identifying increased vascularity in 21 cases compared with the anterior/posterior views positive in only 11 cases. The inter-reviewer agreement was near perfect for lateral/medial views, κ = 0.86 while very good for anterior/posterior views, κ = 0.68. In patients with suspected tibial stress fractures, lateral views of the tibia provide the optimal method for evaluation of vascularity. Prospective studies with quantitative or semi-quantitative assessment of skeletal vascularity could provide supplementary information relating to the pathophysiology

The value of innovation under value-based pricing.

PubMed

Moreno, Santiago G; Ray, Joshua A

2016-01-01

The role of cost-effectiveness analysis (CEA) in incentivizing innovation is controversial. Critics of CEA argue that its use for pricing purposes disregards the 'value of innovation' reflected in new drug development, whereas supporters of CEA highlight that the value of innovation is already accounted for. Our objective in this article is to outline the limitations of the conventional CEA approach, while proposing an alternative method of evaluation that captures the value of innovation more accurately. The adoption of a new drug benefits present and future patients (with cost implications) for as long as the drug is part of clinical practice. Incidence patients and off-patent prices are identified as two key missing features preventing the conventional CEA approach from capturing 1) benefit to future patients and 2) future savings from off-patent prices. The proposed CEA approach incorporates these two features to derive the total lifetime value of an innovative drug (i.e., the value of innovation). The conventional CEA approach tends to underestimate the value of innovative drugs by disregarding the benefit to future patients and savings from off-patent prices. As a result, innovative drugs are underpriced, only allowing manufacturers to capture approximately 15% of the total value of innovation during the patent protection period. In addition to including the incidence population and off-patent price, the alternative approach proposes pricing new drugs by first negotiating the share of value of innovation to be appropriated by the manufacturer (>15%?) and payer (<85%?), in order to then identify the drug price that satisfies this condition. We argue for a modification to the conventional CEA approach that integrates the total lifetime value of innovative drugs into CEA, by taking into account off-patent pricing and future patients. The proposed approach derives a price that allows manufacturers to capture an agreed share of this value, thereby incentivizing

Evaluation of assigned-value uncertainty for complex calibrator value assignment processes: a prealbumin example.

PubMed

Middleton, John; Vaks, Jeffrey E

2007-04-01

Errors of calibrator-assigned values lead to errors in the testing of patient samples. The ability to estimate the uncertainties of calibrator-assigned values and other variables minimizes errors in testing processes. International Organization of Standardization guidelines provide simple equations for the estimation of calibrator uncertainty with simple value-assignment processes, but other methods are needed to estimate uncertainty in complex processes. We estimated the assigned-value uncertainty with a Monte Carlo computer simulation of a complex value-assignment process, based on a formalized description of the process, with measurement parameters estimated experimentally. This method was applied to study uncertainty of a multilevel calibrator value assignment for a prealbumin immunoassay. The simulation results showed that the component of the uncertainty added by the process of value transfer from the reference material CRM470 to the calibrator is smaller than that of the reference material itself (<0.8% vs 3.7%). Varying the process parameters in the simulation model allowed for optimizing the process, while keeping the added uncertainty small. The patient result uncertainty caused by the calibrator uncertainty was also found to be small. This method of estimating uncertainty is a powerful tool that allows for estimation of calibrator uncertainty for optimization of various value assignment processes, with a reduced number of measurements and reagent costs, while satisfying the requirements to uncertainty. The new method expands and augments existing methods to allow estimation of uncertainty in complex processes.

Residual stress at fluid interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murray, P.E.

We extend the Navier-Stokes equations to allow for residual stress in Newtonian fluids. A fluid, which undergoes a constrained volume change, will have residual stress. Corresponding to every constrained volume change is an eigenstrain. We present a method to include in the equations of fluid motion the eigenstrain that is a result of the presence in a fluid of a soluble chemical species. This method is used to calculate the residual stress associated with a chemical transformation. 9 refs., 1 fig.

Hyperspectral image analysis for plant stress detection

USDA-ARS?s Scientific Manuscript database

Abiotic and disease-induced stress significantly reduces plant productivity. Automated on-the-go mapping of plant stress allows timely intervention and mitigating of the problem before critical thresholds are exceeded, thereby, maximizing productivity. A hyperspectral camera analyzed the spectral ...

Evaluation of small-diameter timber for value-added manufacturing : a stress wave approach

Treesearch

Xiping Wang; Robert J. Ross; John Punches; R. James Barbour; John W. Forsman; John R. Erickson

2003-01-01

The objective of this research was to investigate the use of a stress wave technology to evaluate the structural quality of small-diameter timber before harvest. One hundred and ninety-two Douglas-fir and ponderosa pine trees were sampled from four stands in southwestern Oregon and subjected to stress wave tests in the field. Twelve of the trees, six Douglas-fir and...

Sources of Confusion in the Determination of ASTM Repetitive Member Factors for the Allowable Properties of Wood Products

Treesearch

S. Verrill; D. Kretschmann

2012-01-01

It is generally accepted that there should be an upward repetitive member allowable property adjustment. ASTM D245 (2011c) and ASTM D1990 (2011b) specify a 1.15 factor for allowable bending stress. This factor is also listed in ASTM D6555 (2011a, Table 1). In this technical note, sources of confusion regarding appropriate repetitive member factors are identified. This...

Determination of necking time in tensile test specimens, under high-temperature creep conditions, subjected to distribution of stresses over the cross-section

NASA Astrophysics Data System (ADS)

Lokoshchenko, A.; Teraud, W.

2018-04-01

The work describes an experimental research of creep of cylindrical tensile test specimens made of aluminum alloy D16T at a constant temperature of 400°C. The issue to be examined was the necking at different values of initial tensile stresses. The use of a developed noncontacting measuring system allowed us to see variations in the specimen shape and to estimate the true stress in various times. Based on the obtained experimental data, several criteria were proposed for describing the point of time at which the necking occurs (necking point). Calculations were carried out at various values of the parameters in these criteria. The relative interval of deformation time in which the test specimen is uniformly stretched was also determined.

Growth characteristics of a plane crack subjected to three-dimensional loading. [based on stress intensity factors

NASA Technical Reports Server (NTRS)

Hartranft, R. J.; Sih, G. C.

1973-01-01

The closed form expressions for the stress intensity factors due to concentrated forces applied to the surfaces of a half plane crack in an infinite body are used to generate solutions for distributed loads in this geometry. The stress intensity factors for uniformly distributed loads applied over a rectangular portion of the crack surface are given in closed form. An example of non-uniformly distributed loads which can be treated numerically is also included. In particular, combinations of normal and shear stresses on the crack which simulate the case of loading at an angle to the crack front are considered. The resulting stress intensity factors are combined with the strain energy density fracture criterion for the purpose of predicting the most likely direction of crack propagation. The critical value of the energy density factor can then be used for determining the allowable load on a specimen with a crack front not perpendicular to the tensile axis.

Comfort food is comforting to those most stressed: evidence of the chronic stress response network in high stress women.

PubMed

Tomiyama, A Janet; Dallman, Mary F; Epel, Elissa S

2011-11-01

Chronically stressed rodents who are allowed to eat calorie-dense "comfort" food develop greater mesenteric fat, which in turn dampens hypothalamic-pituitary-adrenocortical (HPA) axis activity. We tested whether similar relations exist in humans, at least cross-sectionally. Fifty-nine healthy premenopausal women were exposed to a standard laboratory stressor to examine HPA response to acute stress and underwent diurnal saliva sampling for basal cortisol and response to dexamethasone administration. Based on perceived stress scores, women were divided into extreme quartiles of low versus high stress categories. We found as hypothesized that the high stress group had significantly greater BMI and sagittal diameter, and reported greater emotional eating. In response to acute lab stressor, the high stress group showed a blunted cortisol response, lower diurnal cortisol levels, and greater suppression in response to dexamethasone. These cross-sectional findings support the animal model, which suggests that long-term adaptation to chronic stress in the face of dense calories result in greater visceral fat accumulation (via ingestion of calorie-dense food), which in turn modulates HPA axis response, resulting in lower cortisol levels. Copyright © 2011 Elsevier Ltd. All rights reserved.

Refraction of the principal stress trajectories and the stress jumps on faults and contact surfaces: Part 1. Non-constrained regular trajectories

NASA Astrophysics Data System (ADS)

Mukhamediev, Sh. A.

2014-09-01

is reduced to a beach-ball plot, which visualizes the focal mechanism solution of an earthquake. If area n is a generally oriented plane and if the orientation of the pairs of the statically compatible axes T {1/-}, T {3/-} and T {1/+}, T {3/+} is specified, then, the stress values on side + are uniquely determined from the known stress values on side -. From the value of differential stress ratio R -, one can calculate the value of R +, and using the values of the principal stresses on side -, determine the total stress tensor T + on side +. The obtained results are supported by the laboratory experiments and drilling data. In particular, these results disclose the drawbacks of some established notions and methods in which the possible refraction of the stress axes is unreasonably ignored or taken into account improperly. For example, it is generally misleading to associate the slip on the preexisting fault with the orientation of any particular trihedron of the principal stress axes. The reconstruction should address the potentially statically compatible principal stress axes, which are differently oriented on opposite sides of the fault plane. The fact that, based on the orientation of the intraplate principal stresses at the base of the lithosphere, one cannot make a conclusion on the active or passive influence of the mantle flows on the lithospheric plate motion is another example. The present relationships linking the stress values on the opposite sides of the fault plane on which the orientations of the principal stress axes are known demonstrate the incorrectness of the existing methods, in which the reduced stress tensors within the material domains are reconstructed without allowance for the dynamic interaction of these domains with their neighbors. In addition, using the obtained results, one can generalize the notion of the zone of dynamical control of a fault onto the case of the existence of discontinuities in this region and analyze the stress

Investigation and Modeling of Cranberry Weather Stress.

NASA Astrophysics Data System (ADS)

Croft, Paul Joseph

Cranberry bog weather conditions and weather-related stress were investigated for development of crop yield prediction models and models to predict daily weather conditions in the bog. Field investigations and data gathering were completed at the Rutgers University Blueberry/Cranberry Research Center experimental bogs in Chatsworth, New Jersey. Study indicated that although cranberries generally exhibit little or no stomatal response to changing atmospheric conditions, the evaluation of weather-related stress could be accomplished via use of micrometeorological data. Definition of weather -related stress was made by establishing critical thresholds of the frequencies of occurrence, and magnitudes of, temperature and precipitation in the bog based on values determined by a review of the literature and a grower questionnaire. Stress frequencies were correlated with cranberry yield to develop predictive models based on the previous season's yield, prior season data, prior and current season data, current season data; and prior and current season data through July 31 of the current season. The predictive ability of the prior season models was best and could be used in crop planning and production. Further examination of bog micrometeorological data permitted the isolation of those weather conditions conducive to cranberry scald and allowed for the institution of a pilot scald advisory program during the 1991 season. The micrometeorological data from the bog was also used to develop models to predict daily canopy temperature and precipitation, based on upper air data, for grower use. Models were developed for each month for maximum and minimum temperatures and for precipitation and generally performed well. The modeling of bog weather conditions is an important first step toward daily prediction of cranberry weather-related stress.

Managing Time and Stress.

ERIC Educational Resources Information Center

Huffstutter, Sandra; Smith, Stuart C.

Chapter 14 of a revised volume on school leadership, this chapter offers many practical suggestions for managing time and reducing stress. The primary challenge is to unblock the route to effective time/stress management by recognizing unproductive values and attitudes (such as overreliance on the Protestant work ethic or the appearance of…

Consequences of Stress for Public School Superintendents

ERIC Educational Resources Information Center

Carroll, Kathy J.

2010-01-01

Scope and Method of Study: This study is a quantitative study of Oklahoma Public School Superintendents. The data was collected by surveys using an online format. Data was analyzed to determine correlation and predictive values of the four specific stress factors: conflict mediating stress, boundary spanning stress, task based stress and role…

Space allowance during commercial long distance transport of cattle in North America.

PubMed

González, L A; Schwartzkopf-Genswein, K S; Bryan, M; Silasi, R; Brown, F

2012-10-01

The objective of the present work was to study space allowance in cattle during commercial long haul transport (≥400 km; n = 6,152 journeys). Surveys, delivered to livestock transport carriers, gathered information on the number, BW, and distribution of cattle by trailer compartment as well as the characteristics of the transport vehicles used. Space allowance (SA; m(2)/animal), allometric coefficient (k = SA / BW(0.6667)), and the percentage of deviation from recommended SA (DRSA; %) in the Canadian Codes of Practice were calculated for each compartment of the trailers. All quad-axle (77%) and tri-axle (23%) cattle trailers were reported with 5 compartments (nose, deck, belly, back, and doghouse). Sixty percent of all animals were carried in the middle compartments (deck and belly), 30% in the rear (back and doghouse), and 10% in the front or nose. Approximately 30% of the journeys required that the cattle be redistributed at the Canada-USA border to comply with different axle weight regulations, and most journeys moved them between the deck and the doghouse. Total loaded weight increased and the number of animals decreased with increasing BW of the animals. space allowance, k-value, and DRSA were least for calves and feeders compared with fat and cull cattle (p < 0.01). Both total loaded weight and number of animals increased with the number of axles in the trailer, being greatest in quad-axle trailers pulled by push tractors, which were most frequently used. Space allowance (k-value) was least in vehicles with greater number of axles and transporting the lightest cattle (i.e., quad-axles trailers transporting calves and feeders). Space allowance, k-value, and variability among journeys were least in the middle compartments (belly and deck), followed by the back, then doghouse and nose compartments of the trailers showing the largest values (p < 0.05). Many factors contributed to the variability in SA such as body size (smaller animals are placed more densely

High-value bioproducts from microalgae: strategies and progress.

PubMed

Liang, Ming-Hua; Zhu, Jianhua; Jiang, Jian-Guo

2018-04-20

Microalgae have been considered as alternative sustainable resources for high-value bioproducts such as lipids (especially triacylglycerides [TAGs]), polyunsaturated fatty acids (PUFAs), and carotenoids, due to their relatively high photosynthetic efficiency, no arable land requirement, and ease of scale-up. It is of great significance to exploit microalgae for the production of high-value bioproducts. How to improve the content or productivity of specific bioproducts has become one of the most urgent challenges. In this review, we will describe high-value bioproducts from microalgae and their biosynthetic pathways (mainly for lipids, PUFAs, and carotenoids). Recent progress and strategies for the enhanced production of bioproducts from microalgae are also described in detail, and these strategies take advantages of optimized cultivation conditions with abiotic stress, chemical stress (addition of metabolic precursors, phytohormones, chemical inhibitors, and chemicals inducing oxidative stress response), and molecular approaches such as metabolic engineering, transcriptional engineering, and gene disruption strategies (mainly RNAi, antisense RNA, miRNA-based knockdown, and CRISPR/Cas9).

The effect of three space allowances on the physiology and behavior of weaned pigs during transportation

USDA-ARS?s Scientific Manuscript database

Stocking density is an important aspect of transport which could affect animal health and welfare, especially in pigs simultaneously experiencing weaning stress. The objective of this research was to evaluate the effect of three different space allowances on the physiology and behavior of weaned pig...

WEB downloadable software for training in cardiovascular hemodynamics in the (3-D) stress echo lab

PubMed Central

2010-01-01

When a physiological (exercise) stress echo is scheduled, interest focuses on wall motion segmental contraction abnormalities to diagnose ischemic response to stress, and on left ventricular ejection fraction to assess contractile reserve. Echocardiographic evaluation of volumes (plus standard assessment of heart rate and blood pressure) is ideally suited for the quantitative and accurate calculation of a set of parameters allowing a complete characterization of cardiovascular hemodynamics (including cardiac output and systemic vascular resistance), left ventricular elastance (mirroring left ventricular contractility, theoretically independent of preload and afterload changes heavily affecting the ejection fraction), arterial elastance, ventricular arterial coupling (a central determinant of net cardiovascular performance in normal and pathological conditions), and diastolic function (through the diastolic mean filling rate). All these parameters were previously inaccessible, inaccurate or labor-intensive and now become, at least in principle, available in the stress echocardiography laboratory since all of them need an accurate estimation of left ventricular volumes and stroke volume, easily derived from 3 D echo. Aims of this paper are: 1) to propose a simple method to assess a set of parameters allowing a complete characterization of cardiovascular hemodynamics in the stress echo lab, from basic measurements to calculations 2) to propose a simple, web-based software program, to learn and training calculations as a phantom of the everyday activity in the busy stress echo lab 3) to show examples of software testing in a way that proves its value. The informatics infrastructure is available on the web, linking to http://cctrainer.ifc.cnr.it PMID:21073738

Diagnostic performance of dual-energy CT stress myocardial perfusion imaging: direct comparison with cardiovascular MRI.

PubMed

Ko, Sung Min; Song, Meong Gun; Chee, Hyun Kun; Hwang, Hweung Kon; Feuchtner, Gudrun Maria; Min, James K

2014-12-01

The purpose of this study was to assess the diagnostic performance of stress perfusion dual-energy CT (DECT) and its incremental value when used with coronary CT angiography (CTA) for identifying hemodynamically significant coronary artery disease. One hundred patients with suspected or known coronary artery disease without chronic myocardial infarction detected with coronary CTA underwent stress perfusion DECT, stress cardiovascular perfusion MRI, and invasive coronary angiography (ICA). Stress perfusion DECT and cardiovascular stress perfusion MR images were used for detecting perfusion defects. Coronary CTA and ICA were evaluated in the detection of ≥50% coronary stenosis. The diagnostic performance of coronary CTA for detecting hemo-dynamically significant stenosis was assessed before and after stress perfusion DECT on a per-vessel basis with ICA and cardiovascular stress perfusion MRI as the reference standard. The performance of stress perfusion DECT compared with cardiovascular stress perfusion MRI on a per-vessel basis in the detection of perfusion defects was sensitivity, 89%; specificity, 74%; positive predictive value, 73%; negative predictive value, 90%. Per segment, these values were sensitivity, 76%; specificity, 80%; positive predictive value, 63%; and negative predictive value, 88%. Compared with ICA and cardiovascular stress perfusion MRI per vessel territory the sensitivity, specificity, positive predictive value, and negative predictive value of coronary CTA were 95%, 61%, 61%, and 95%. The values for stress perfusion DECT were 92%, 72%, 68%, and 94%. The values for coronary CTA and stress perfusion DECT were 88%, 79%, 73%, and 91%. The ROC AUC increased from 0.78 to 0.84 (p=0.02) with the use of coronary CTA and stress perfusion DECT compared with coronary CTA alone. Stress perfusion DECT plays a complementary role in enhancing the accuracy of coronary CTA for identifying hemodynamically significant coronary stenosis.

Expanding the 2011 Prague, OK Event Catalog: Detections, Relocations, and Stress Drop Estimates

NASA Astrophysics Data System (ADS)

Clerc, F.; Cochran, E. S.; Dougherty, S. L.; Keranen, K. M.; Harrington, R. M.

2016-12-01

The Mw 5.6 earthquake occurring on 6 Nov. 2011, near Prague, OK, is thought to have been triggered by a Mw 4.8 foreshock, which was likely induced by fluid injection into local wastewater disposal wells [Keranen et al., 2013; Sumy et al., 2014]. Previous stress drop estimates for the sequence have suggested values lower than those for most Central and Eastern U.S. tectonic events of similar magnitudes [Hough, 2014; Sun & Hartzell, 2014; Sumy & Neighbors et al., 2016]. Better stress drop estimates allow more realistic assessment of seismic hazard and more effective regulation of wastewater injection. More reliable estimates of source properties may help to differentiate induced events from natural ones. Using data from local and regional networks, we perform event detections, relocations, and stress drop calculations of the Prague aftershock sequence. We use the Match & Locate method, a variation on the matched-filter method which detects events of lower magnitudes by stacking cross-correlograms from different stations [Zhang & Wen, 2013; 2015], in order to create a more complete catalog from 6 Nov to 31 Dec 2011. We then relocate the detected events using the HypoDD double-difference algorithm. Using our enhanced catalog and relocations, we examine the seismicity distribution for evidence of migration and investigate implications for triggering mechanisms. To account for path and site effects, we calculate stress drops using the Empirical Green's Function (EGF) spectral ratio method, beginning with 2730 previously relocated events. We determine whether there is a correlation between the stress drop magnitudes and the spatial and temporal distribution of events, including depth, position relative to existing faults, and proximity to injection wells. Finally, we consider the range of stress drop values and scaling with respect to event magnitudes within the context of previously published work for the Prague sequence as well as other induced and natural sequences.

Residual stresses in a stainless steel - titanium alloy joint made with the explosive technique

NASA Astrophysics Data System (ADS)

Taran, Yu V.; Balagurov, A. M.; Sabirov, B. M.; Evans, A.; Davydov, V.; Venter, A. M.

2012-02-01

Joining of pipes from stainless steel (SS) and titanium (Ti) alloy still experience serious technical problems. Recently, reliable and hermetic joining of SS and Ti pipes has been achieved with the explosive bonding technique in the Russian Federal Nuclear Center. Such adapters are earmarked for use at the future International Linear Collider. The manufactured SS-Ti adapters have excellent mechanical behavior at room and liquid nitrogen temperatures, during high-pressure tests and thermal cycling. We here report the first neutron diffraction investigation of the residual stresses in a SS-Ti adapter on the POLDI instrument at the SINQ spallation source. The strain scanning across the adapter walls into the SS-SS and SS-Ti pipes sections encompassed measurement of the axial, radial and hoop strain components, which were transformed into residual stresses. The full stress information was successfully determined for the three steel pipes involved in the joint. The residual stresses do not exceed 300 MPa in magnitude. All stress components have tensile values close to the adapter internal surface, whilst they are compressive close to the outer surface. The strong incoherent and weak coherent neutron scattering cross-sections of Ti did not allow for the reliable determination of stresses inside the titanic pipe.

The value of innovation under value-based pricing

PubMed Central

Moreno, Santiago G.; Ray, Joshua A.

2016-01-01

Objective The role of cost-effectiveness analysis (CEA) in incentivizing innovation is controversial. Critics of CEA argue that its use for pricing purposes disregards the ‘value of innovation’ reflected in new drug development, whereas supporters of CEA highlight that the value of innovation is already accounted for. Our objective in this article is to outline the limitations of the conventional CEA approach, while proposing an alternative method of evaluation that captures the value of innovation more accurately. Method The adoption of a new drug benefits present and future patients (with cost implications) for as long as the drug is part of clinical practice. Incidence patients and off-patent prices are identified as two key missing features preventing the conventional CEA approach from capturing 1) benefit to future patients and 2) future savings from off-patent prices. The proposed CEA approach incorporates these two features to derive the total lifetime value of an innovative drug (i.e., the value of innovation). Results The conventional CEA approach tends to underestimate the value of innovative drugs by disregarding the benefit to future patients and savings from off-patent prices. As a result, innovative drugs are underpriced, only allowing manufacturers to capture approximately 15% of the total value of innovation during the patent protection period. In addition to including the incidence population and off-patent price, the alternative approach proposes pricing new drugs by first negotiating the share of value of innovation to be appropriated by the manufacturer (>15%?) and payer (<85%?), in order to then identify the drug price that satisfies this condition. Conclusion We argue for a modification to the conventional CEA approach that integrates the total lifetime value of innovative drugs into CEA, by taking into account off-patent pricing and future patients. The proposed approach derives a price that allows manufacturers to capture an agreed share

Effects of shear stress on the microalgae Chaetoceros muelleri

PubMed Central

van der Goot, Atze J.; Norsker, Niels-Henrik; Wijffels, René H.

2010-01-01

The effect of shear stress on the viability of Chaetoceros muelleri was studied using a combination of a rheometer and dedicated shearing devices. Different levels of shear stress were applied by varying the shear rates and the medium viscosities. It was possible to quantify the effect of shear stress over a wide range, whilst preserving laminar flow conditions through the use of a thickening agent. The threshold value at which the viability of algae was negatively influenced was between 1 and 1.3 Pa. Beyond the threshold value the viability decreased suddenly to values between 52 and 66%. The effect of shear stress was almost time independent compared to normal microalgae cultivation times. The main shear stress effect was obtained within 1 min, with a secondary effect of up to 8 min. PMID:20191365

Study of stress-strain state of pipeline under permafrost conditions

NASA Astrophysics Data System (ADS)

Tarasenko, A. A.; Redutinskiy, M. N.; Chepur, P. V.; Gruchenkova, A. A.

2018-05-01

In this paper, the dependences of the stress-strain state and subsidence of pipelines on the dimensions of the subsidence zone are obtained for the sizes of pipes that have become most widespread during the construction of main oil pipelines (530x10, 820x12, 1020x12, 1020x14, 1020x16, 1220x14, 1220x16, 1220x18 mm). True values of stresses in the pipeline wall, as well as the exact location of maximum stresses for the interval of subsidence zones from 5 to 60 meters, are determined. For this purpose, the authors developed a finite element model of the pipeline that takes into account the actual interaction of the pipeline with the subgrade and allows calculating the SSS of the structure for a variable subsidence zone. Based on the obtained dependences for the underground laying of oil pipelines in permafrost areas, it is proposed to artificially limit the zone of possible subsidence by separation supports from the soil with higher building properties and physical-mechanical parameters. This technical solution would significantly reduce costs when constructing new oil pipelines in permafrost areas.

Social stress models in depression research: what do they tell us?

PubMed Central

Chaouloff, Francis

2013-01-01

There has been a recent surge of interest in the use of social stress models, especially social defeat. Such an interest lies both on the recognition that stressors of social origin play a major role in human psychopathologies and on the acknowledgement that natural and hence ethologically-based stress models bear important translational value. The use of the most recent technology has allowed the recognition of the mechanisms through which social defeat may have enduring psychoneuroendocrine effects, especially social avoidance and anhedonia, two behaviours relevant to human depression. Taken with the sensitivity of these behavioural outcomes to repeated antidepressant treatments, it has been proposed that the social defeat model might be an animal model of depression. The present survey is aimed at examining the limits of such an interpretation, focusing on methodological aspects and on the relevance of social defeat to the study of anxiety-related pathologies. PMID:23532563

Values: the dynamic nexus between biology, ecology and culture.

PubMed

Fischer, Ronald; Boer, Diana

2016-04-01

Values are motivational goals that influence attitudes, behaviors and evaluations. Cross-cultural evidence suggests that values show a systematic structure. Personal and cultural variations in the value structure, value priorities and value links to attitudes, behavior and well-being reflect contextual constraints and affordances in the environment, suggesting that values function as broadly adaptive psychological structures. The internal structure of values (the descriptive value system) becomes more clearly differentiated in more economically developed contexts. Value priorities shift toward more autonomous, self-expressive and individualistic orientations with greater economic resources and less ecological stress. In addition to systematic changes in internal structure, value links to attitudes, behaviors and well-being are influenced by economic, ecological and institutional contexts. Values are more likely to be expressed in attitudes and behavior if individuals have greater access to economic resources, experience less institutional and ecological stress or when the values reinforce culturally normative behavior. Frontiers for further value research include a greater examination of the neural underpinnings of values in specific ecological contexts and across the lifespan; and an examination of how values are behaviorally instantiated in different environments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Profiled Roller Stress/Fatigue Life Analysis Methodology and Establishment of an Appropriate Stress/Life Exponent

NASA Technical Reports Server (NTRS)

1997-01-01

The objective of this work was to determine the three dimensional volumetric stress field, surface pressure distribution and actual contact area between a 0.50" square roller with different crown profiles and a flat raceway surface using Finite Element Analysis. The 3-dimensional stress field data was used in conjunction with several bearing fatigue life theories to extract appropriate values for stress-life exponents. Also, results of the FEA runs were used to evaluate the laminated roller model presently used for stress and life prediction.

Testing the stress shadow hypothesis

NASA Astrophysics Data System (ADS)

Felzer, Karen R.; Brodsky, Emily E.

2005-05-01

A fundamental question in earthquake physics is whether aftershocks are predominantly triggered by static stress changes (permanent stress changes associated with fault displacement) or dynamic stresses (temporary stress changes associated with earthquake shaking). Both classes of models provide plausible explanations for earthquake triggering of aftershocks, but only the static stress model predicts stress shadows, or regions in which activity is decreased by a nearby earthquake. To test for whether a main shock has produced a stress shadow, we calculate time ratios, defined as the ratio of the time between the main shock and the first earthquake to follow it and the time between the last earthquake to precede the main shock and the first earthquake to follow it. A single value of the time ratio is calculated for each 10 × 10 km bin within 1.5 fault lengths of the main shock epicenter. Large values of the time ratio indicate a long wait for the first earthquake to follow the main shock and thus a potential stress shadow, whereas small values indicate the presence of aftershocks. Simulations indicate that the time ratio test should have sufficient sensitivity to detect stress shadows if they are produced in accordance with the rate and state friction model. We evaluate the 1989 MW 7.0 Loma Prieta, 1992 MW 7.3 Landers, 1994 MW 6.7 Northridge, and 1999 MW 7.1 Hector Mine main shocks. For each main shock, there is a pronounced concentration of small time ratios, indicating the presence of aftershocks, but the number of large time ratios is less than at other times in the catalog. This suggests that stress shadows are not present. By comparing our results to simulations we estimate that we can be at least 98% confident that the Loma Prieta and Landers main shocks did not produce stress shadows and 91% and 84% confident that stress shadows were not generated by the Hector Mine and Northridge main shocks, respectively. We also investigate the long hypothesized existence

A phase-field approach to nonequilibrium phase transformations in elastic solids via an intermediate phase (melt) allowing for interface stresses.

PubMed

Momeni, Kasra; Levitas, Valery I

2016-04-28

A phase-field approach for phase transformations (PTs) between three different phases at nonequilibrium temperatures is developed. It includes advanced mechanics, thermodynamically consistent interfacial stresses, and interface interactions. A thermodynamic Landau-Ginzburg potential developed in terms of polar order parameters satisfies the desired instability and equilibrium conditions for homogeneous phases. The interfacial stresses were introduced with some terms from large-strain formulation even though the small-strain assumption was utilized. The developed model is applied to study the PTs between two solid phases via a highly disordered intermediate phase (IP) or an intermediate melt (IM) hundreds of degrees below the melting temperature. In particular, the β ↔ δ PTs in HMX energetic crystals via IM are analyzed. The effects of various parameters (temperature, ratios of widths and energies of solid-solid (SS) to solid-melt (SM) interfaces, elastic energy, and interfacial stresses) on the formation, stability, and structure of the IM within a propagating SS interface are studied. Interfacial and elastic stresses within a SS interphase and their relaxation and redistribution with the appearance of a partial or complete IM are analyzed. The energy and structure of the critical nucleus (CN) of the IM are studied as well. In particular, the interfacial stresses increase the aspect-ratio of the CN. Although including elastic energy can drastically reduce the energy of the CN of the IM, the activation energy of the CN of the IM within the SS interface increases when interfacial tension is taken into account. The developed thermodynamic potential can also be modified to model other multiphase physical phenomena, such as multi-variant martensitic PTs, grain boundary and surface-induced pre-melting and PTs, as well as developing phase diagrams for IPs.

Overdenture retaining bar stress distribution: a finite-element analysis.

PubMed

Caetano, Conrado Reinoldes; Mesquita, Marcelo Ferraz; Consani, Rafael Leonardo Xediek; Correr-Sobrinho, Lourenço; Dos Santos, Mateus Bertolini Fernandes

2015-05-01

Evaluate the stress distribution on the peri-implant bone tissue and prosthetic components of bar-clip retaining systems for overdentures presenting different implant inclinations, vertical misfit and framework material. Three-dimensional models of a jaw and an overdenture retained by two implants and a bar-clip attachment were modeled using specific software (SolidWorks 2010). The studied variables were: latero-lateral inclination of one implant (-10°, -5°, 0°, +5°, +10°); vertical misfit on the other implant (50, 100, 200 µm); and framework material (Au type IV, Ag-Pd, Ti cp, Co-Cr). Solid models were imported into mechanical simulation software (ANSYS Workbench 11). All nodes on the bone's external surface were constrained and a displacement was applied to simulate the settling of the framework on the ill-fitted component. Von Mises stress for the prosthetic components and maximum principal stress to the bone tissue were evaluated. The +10° inclination presented the worst biomechanical behavior, promoting the highest stress values on the bar framework and peri-implant bone tissue. The -5° group presented the lowest stress values on the prosthetic components and the lowest stress value on peri-implant bone tissue was observed in -10°. Increased vertical misfit caused an increase on the stress values in all evaluated structures. Stiffer framework materials caused a considerable stress increase in the framework itself, prosthetic screw of the fitted component and peri-implant bone tissue. Inclination of one implant associated with vertical misfit caused a relevant effect on the stress distribution in bar-clip retained overdentures. Different framework materials promoted increased levels of stress in all the evaluated structures.

The effect of copper doping on martensite shear stress in porous TiNi(Mo,Fe,Cu) alloys

NASA Astrophysics Data System (ADS)

Khodorenko, V. N.; Kaftaranova, M. I.; Gunther, V. E.

2015-03-01

The properties of alloys based on porous nickel-titanium (TiNi) with copper additives have been studied. It is established that the copper doping of porous TiNi(Mo,Fe,Cu) alloys fabricated by the method of self-propagating high-temperature synthesis leads to a significant decrease in the martensite shear stress (below 30 MPa). Low values of the martensite shear stress (σmin) in copper-doped TiNi-based alloys allows medical implants of complex shapes to be manufactured for various purposes, including oral surgery. The optimum concentration of copper additives (within 3-6 at %) has been determined that ensures high performance characteristics of TiNi-based porous alloys for medical implants.

An ultrasonic technique for measuring stress in fasteners

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stevens, K. J.; Day, P.; Byron, D.

1999-12-02

High temperature bolting alloys are extensively used in the thermal power generation industry as for example, reheat ESV and Governor valve studs. Remnant life assessment methodologies and plant maintenance procedures require the monitoring of the operational stress levels in these fasteners. Some conventional ultrasonic techniques require longitudinal wave measurements to be undertaken when the nut on the bolt is loosened and then re-tightened. Other techniques use a combination of shear waves and longitudinal waves. In this paper, the problems and pitfalls associated with various ultrasonic techniques for measuring stress in bolts, is discussed. An ultrasonic technique developed for measuring themore » stress in Durehete 1055 bolts is presented. Material from a textured rolled bar has been used as a test bed in the development work. The technique uses shear wave birefringence and compression waves at several frequencies to measure texture, fastener length and the average stress. The technique was developed by making ultrasonic measurements on bolts tensioned in universal testing machines and a hydraulic nut. The ultrasonic measurements of residual stress have been checked against strain gauge measurements. The Durehete bolts have a hollow cylinder geometry of restricted dimensions, which significantly alters compression and shear wave velocities from bulk values and introduces hoop stresses which can be measured by rotating the polarization of the shear wave probe. Modelling of the experimental results has been undertaken using theories for the elastic wave propagation through waveguides. The dispersion equations allow the velocity and length of the fastener to be measured ultrasonically in some situations where the length of the fastener can not be measured directly with a vernier caliper or micrometer and/or where it is undesirable to loosen nuts to take calibration readings of the shear and compression wave velocities.« less

The influence of visco-elastic processes on the generation of thermal stresses in quenched low alloy steel plates

NASA Astrophysics Data System (ADS)

Abbasi, F.

The visco-elastic effect in quenched specimens of 835M30 steel was described quantitatively by the use of the standard linear solid, which allowed the calculation of the thermal stress and strain during quenching in water, oil and in a martempering situation. The introduction of viscous flow into the calculation produced a marked improvement in the degree of agreement between the calculated and experimental residual stresses after an oil quench, although this was accompanied by a small reduction in the corresponding agreement in the case of water quench. The use of isothermal stress relaxation data in a continuous cooling situation was dealt with by the use of several models that cover a range of situations that varied from progressive hardening during the quench to one where recovery was predominant at all times. The use of martempering was of limited value, although an air cool following an intermediate salt bath treatment above the Ms temperature prevented the generation of thermal stresses during the formation of martensite. The use of an oil quench following the salt bath treatment was of no value, and none of the combinations of heat treatment possible during martempering significantly reduced the distortions to a lower level than was obtained by a conventional oil quench from 850°C. The mathematical model was also extended to include the effect of transformation plasticity, viz. the effect of an applied stress on the volume change that accompanied a phase transformation, as a consequence of heterogeneous plastic flow. This led to an excellent level of agreement between calculation and experiment in the case of residual stresses: it also produced adeterioration in the case of residual strains. Although some further work is required, the mathematical model has been developed sufficiently for it to be of practical value.

An updated stress map of the continental United States reveals heterogeneous intraplate stress

NASA Astrophysics Data System (ADS)

Levandowski, Will; Herrmann, Robert B.; Briggs, Rich; Boyd, Oliver; Gold, Ryan

2018-06-01

Knowledge of the state of stress in Earth's crust is key to understanding the forces and processes responsible for earthquakes. Historically, low rates of natural seismicity in the central and eastern United States have complicated efforts to understand intraplate stress, but recent improvements in seismic networks and the spread of human-induced seismicity have greatly improved data coverage. Here, we compile a nationwide stress map based on formal inversions of focal mechanisms that challenges the idea that deformation in continental interiors is driven primarily by broad, uniform stress fields derived from distant plate boundaries. Despite plate-boundary compression, extension dominates roughly half of the continent, and second-order forces related to lithospheric structure appear to control extension directions. We also show that the states of stress in several active eastern United States seismic zones differ significantly from those of surrounding areas and that these anomalies cannot be explained by transient processes, suggesting that earthquakes are focused by persistent, locally derived sources of stress. Such spatially variable intraplate stress appears to justify the current, spatially variable estimates of seismic hazard. Future work to quantify sources of stress, stressing-rate magnitudes and their relationship with strain and earthquake rates could allow prospective mapping of intraplate hazard.

Gene expression analysis of rocket salad under pre-harvest and postharvest stresses: A transcriptomic resource for Diplotaxis tenuifolia

PubMed Central

Cavaiuolo, Marina; Cocetta, Giacomo; Spadafora, Natasha Damiana; Müller, Carsten T.; Rogers, Hilary J.

2017-01-01

Diplotaxis tenuifolia L. is of important economic value in the fresh-cut industry for its nutraceutical and sensorial properties. However, information on the molecular mechanisms conferring tolerance of harvested leaves to pre- and postharvest stresses during processing and shelf-life have never been investigated. Here, we provide the first transcriptomic resource of rocket by de novo RNA sequencing assembly, functional annotation and stress-induced expression analysis of 33874 transcripts. Transcriptomic changes in leaves subjected to commercially-relevant pre-harvest (salinity, heat and nitrogen starvation) and postharvest stresses (cold, dehydration, dark, wounding) known to affect quality and shelf-life were analysed 24h after stress treatment, a timing relevant to subsequent processing of salad leaves. Transcription factors and genes involved in plant growth regulator signaling, autophagy, senescence and glucosinolate metabolism were the most affected by the stresses. Hundreds of genes with unknown function but uniquely expressed under stress were identified, providing candidates to investigate stress responses in rocket. Dehydration and wounding had the greatest effect on the transcriptome and different stresses elicited changes in the expression of genes related to overlapping groups of hormones. These data will allow development of approaches targeted at improving stress tolerance, quality and shelf-life of rocket with direct applications in the fresh-cut industries. PMID:28558066

Gene expression analysis of rocket salad under pre-harvest and postharvest stresses: A transcriptomic resource for Diplotaxis tenuifolia.

PubMed

Cavaiuolo, Marina; Cocetta, Giacomo; Spadafora, Natasha Damiana; Müller, Carsten T; Rogers, Hilary J; Ferrante, Antonio

2017-01-01

Diplotaxis tenuifolia L. is of important economic value in the fresh-cut industry for its nutraceutical and sensorial properties. However, information on the molecular mechanisms conferring tolerance of harvested leaves to pre- and postharvest stresses during processing and shelf-life have never been investigated. Here, we provide the first transcriptomic resource of rocket by de novo RNA sequencing assembly, functional annotation and stress-induced expression analysis of 33874 transcripts. Transcriptomic changes in leaves subjected to commercially-relevant pre-harvest (salinity, heat and nitrogen starvation) and postharvest stresses (cold, dehydration, dark, wounding) known to affect quality and shelf-life were analysed 24h after stress treatment, a timing relevant to subsequent processing of salad leaves. Transcription factors and genes involved in plant growth regulator signaling, autophagy, senescence and glucosinolate metabolism were the most affected by the stresses. Hundreds of genes with unknown function but uniquely expressed under stress were identified, providing candidates to investigate stress responses in rocket. Dehydration and wounding had the greatest effect on the transcriptome and different stresses elicited changes in the expression of genes related to overlapping groups of hormones. These data will allow development of approaches targeted at improving stress tolerance, quality and shelf-life of rocket with direct applications in the fresh-cut industries.

Quantifying Residual Stresses by Means of Thermoelastic Stress Analysis

NASA Technical Reports Server (NTRS)

Gyekenyesi, Andrew L.; Baaklini, George Y.

2001-01-01

This study focused on the application of the Thermoelastic Stress Analysis (TSA) technique as a tool for assessing the residual stress state of structures. TSA is based on the fact that materials experience small temperature changes when compressed or expanded. When a structure is cyclically loaded, a surface temperature profile results which correlates to the surface stresses. The cyclic surface temperature is measured with an infrared camera. Traditionally, the amplitude of a TSA signal was theoretically defined to be linearly dependent on the cyclic stress amplitude. Recent studies have established that the temperature response is also dependent on the cyclic mean stress (i.e., the static stress state of the structure). In a previous study by the authors, it was shown that mean stresses significantly influenced the TSA results for titanium- and nickel-based alloys. This study continued the effort of accurate direct measurements of the mean stress effect by implementing various experimental modifications. In addition, a more in-depth analysis was conducted which involved analyzing the second harmonic of the temperature response. By obtaining the amplitudes of the first and second harmonics, the stress amplitude and the mean stress at a given point on a structure subjected to a cyclic load can be simultaneously obtained. The experimental results showed good agreement with the theoretical predictions for both the first and second harmonics of the temperature response. As a result, confidence was achieved concerning the ability to simultaneously obtain values for the static stress state as well as the cyclic stress amplitude of structures subjected to cyclic loads using the TSA technique. With continued research, it is now feasible to establish a protocol that would enable the monitoring of residual stresses in structures utilizing TSA.

Texture analysis at neutron diffractometer STRESS-SPEC

NASA Astrophysics Data System (ADS)

Brokmeier, H.-G.; Gan, W. M.; Randau, C.; Völler, M.; Rebelo-Kornmeier, J.; Hofmann, M.

2011-06-01

In response to the development of new materials and the application of materials and components in advanced technologies, non-destructive measurement methods of textures and residual stresses have gained worldwide significance in recent years. The materials science neutron diffractometer STRESS-SPEC at FRM II (Garching, Germany) is designed to be applied equally to texture and residual stress analyses by virtue of its very flexible configuration. Due to the high penetration capabilities of neutrons and the high neutron flux of STRESS-SPEC it allows a combined analysis of global texture, local texture, strain pole figure and FWHM pole figure in a wide variety of materials including metals, alloys, composites, ceramics and geological materials. Especially, the analysis of texture gradients in bulk materials using neutron diffraction has advantages over laboratory X-rays and EBSD for many scientific cases. Moreover, neutron diffraction is favourable for coarse-grained materials, where bulk information averaged over texture inhomogeneities is needed, and also stands out due to easy sample preparation. In future, the newly developed robot system for STRESS-SPEC will allow much more flexibility than an Eulerian cradle as on standard instruments. Five recent measurements are shown to demonstrate the wide range of possible texture applications at STRESS-SPEC diffractometer.

Static-stress analysis of dual-axis confinement vessel

NASA Astrophysics Data System (ADS)

Bultman, D. H.

1992-11-01

This study evaluates the static-pressure containment capability of a 6-ft-diameter, spherical vessel, made of HSLA-100 steel, to be used for high-explosive (HE) containment. The confinement vessel is designed for use with the Dual-Axis Radiographic Hydrotest Facility (DARHT) being developed at Los Alamos National Laboratory. Two sets of openings in the vessel are covered with x-ray transparent covers to allow radiographic imaging of an explosion as it occurs inside the vessel. The confinement vessel is analyzed as a pressure vessel based on the ASME Boiler and Pressure Vessel Code, Section 8, Division 1, and the Welding Research Council Bulletin, WRC-107. Combined stresses resulting from internal pressure and external loads on nozzles are calculated and compared with the allowable stresses for HSLA-100 steel. Results confirm that the shell and nozzles of the confinement vessel are adequately designed to safely contain the maximum residual pressure of 1675 psi that would result from an HE charge of 24.2 kg detonated in a vacuum. Shell stresses at the shell-to-nozzle interface, produced from external loads on the nozzles, were less than 400 psi. The maximum combined stress resulting from the internal pressure plus external loads was 16,070 psi, which is less than half the allowable stress of 42,375 psi for HSLA-100 steel.

Application of the no-signaling principle to obtain quantum cloners for any allowed value of fidelity

NASA Astrophysics Data System (ADS)

Gedik, Z.; Çakmak, B.

2013-04-01

Special relativity forbids superluminal influences. Using only the no-signaling principle and an assumption about the form of the Schmidt decomposition, we show that for any allowed fidelity there is a unique approximate qubit cloner which can be written explicitly. We introduce the prime cloners whose fidelities have multiplicative property and show that the fidelity of the prime cloners for the infinite copy limit is 1/2.

Nanohardness and Residual Stress in TiN Coatings.

PubMed

Hernández, Luis Carlos; Ponce, Luis; Fundora, Abel; López, Enrique; Pérez, Eduardo

2011-05-17

TiN films were prepared by the Cathodic arc evaporation deposition method under different negative substrate bias. AFM image analyses show that the growth mode of biased coatings changes from 3D island to lateral when the negative bias potential is increased. Nanohardness of the thin films was measured by nanoindentation, and residual stress was determined using Grazing incidence X ray diffraction. The maximum value of residual stress is reached at -100 V substrate bias coinciding with the biggest values of adhesion and nanohardness. Nanoindentation measurement proves that the force-depth curve shifts due to residual stress. The experimental results demonstrate that nanohardness is seriously affected by the residual stress.

Allowable Trajectory Variations for Space Shuttle Orbiter Entry-Aeroheating CFD

NASA Technical Reports Server (NTRS)

Wood, William A.; Alter, Stephen J.

2008-01-01

Reynolds-number criteria are developed for acceptable variations in Space Shuttle Orbiter entry trajectories for use in computational aeroheating analyses. The criteria determine if an existing computational fluid dynamics solution for a particular trajectory can be extrapolated to a different trajectory. The criteria development begins by estimating uncertainties for seventeen types of computational aeroheating data, such as boundary layer thickness, at exact trajectory conditions. For each type of datum, the allowable uncertainty contribution due to trajectory variation is set to be half of the value of the estimated exact-trajectory uncertainty. Then, for the twelve highest-priority datum types, Reynolds-number relations between trajectory variation and output uncertainty are determined. From these relations the criteria are established for the maximum allowable trajectory variations. The most restrictive criterion allows a 25% variation in Reynolds number at constant Mach number between trajectories.

Thermal stress in high temperature cylindrical fasteners

NASA Technical Reports Server (NTRS)

Blosser, Max L.

1988-01-01

Uninsulated structures fabricated from carbon or silicon-based materials, which are allowed to become hot during flight, are attractive for the design of some components of hypersonic vehicles. They have the potential to reduce weight and increase vehicle efficiency. Because of manufacturing contraints, these structures will consist of parts which must be fastened together. The thermal expansion mismatch between conventional metal fasteners and carbon or silicon-based structural materials may make it difficult to design a structural joint which is tight over the operational temperature range without exceeding allowable stress limits. In this study, algebraic, closed-form solutions for calculating the thermal stresses resulting from radial thermal expansion mismatch around a cylindrical fastener are developed. These solutions permit a designer to quickly evaluate many combinations of materials for the fastener and the structure. Using the algebraic equations developed, material properties and joint geometry were varied to determine their effect on thermal stresses. Finite element analyses were used to verify that the closed-form solutions derived give the correct thermal stress distribution around a cylindrical fastener and to investigate the effect of some of the simplifying assumptions made in developing the closed-form solutions for thermal stresses.

Strain-Encoded Cardiac Magnetic Resonance Imaging as an Adjunct for Dobutamine Stress Testing. Incremental Value to Conventional Wall Motion Analysis

PubMed Central

Korosoglou, Grigorios; Lossnitzer, Dirk; Schellberg, Dieter; Lewien, Antje; Wochele, Angela; Schaeufele, Tim; Neizel, Mirja; Steen, Henning; Giannitsis, Evangelos; Katus, Hugo A.; Osman, Nael F.

2009-01-01

Background High-dose dobutamine stress magnetic resonance imaging (DS-MRI) is safe and feasible for the diagnosis of coronary artery disease (CAD) in humans. However, the assessment of cine scans relies on the visual interpretation of regional wall motion, which is subjective. Recently, Strain-Encoded MRI (SENC) has been proposed for the direct color-coded visualization of myocardial strain. The purpose of our study was to compare the diagnostic value of SENC to that provided by conventional wall motion analysis for the detection of inducible ischemia during DS-MRI. Methods and Results Stress induced ischemia was assessed by wall motion analysis and by SENC in 101 patients with suspected or known CAD and in 17 healthy volunteers who underwent DS-MRI in a clinical 1.5T scanner. Quantitative coronary angiography deemed as the standard reference for the presence or absence of significant CAD (≥50% diameter stenosis). On a coronary vessel level, SENC detected inducible ischemia in 86/101 versus 71/101 diseased coronary vessels (p<0.01 versus cine), and showed normal strain response in 189/202 versus 194/202 vessels with <50% stenosis (p=NS versus cine). On a patient level, SENC detected inducible ischemia in 63/64 versus 55/64 patients with CAD (p<0.05 versus cine), and showed normal strain response in 32/37 versus 34/37 patients without CAD (p=NS versus cine).Quantification analysis demonstrated a significant correlation between strain rate reserve (SRreserve) and coronary artery stenosis severity (r²=0.56, p<0.001), and a cut-off value of SRreserve=1.64 deemed as a highly accurate marker for the detection of stenosis≥50% (AUC=0.96, SE=0.01, 95% CI = 0.94–0.98, p<0.001). Conclusions The direct color-coded visualization of strain on MR-images is a useful adjunct for DS-MRI, which provides incremental value for the detection of CAD compared to conventional wall motion readings on cine images. PMID:19808579

46 CFR 154.440 - Allowable stress.

Code of Federal Regulations, 2014 CFR

2014-10-01

...: (1) For tank web frames, stringers, or girders of carbon manganese steel or aluminum alloys, meet σB... in appendix A of this part. (c) Tank plating must meet the American Bureau of Shipping's deep tank...

46 CFR 154.440 - Allowable stress.

Code of Federal Regulations, 2013 CFR

2013-10-01

...: (1) For tank web frames, stringers, or girders of carbon manganese steel or aluminum alloys, meet σB... in appendix A of this part. (c) Tank plating must meet the American Bureau of Shipping's deep tank...

46 CFR 154.440 - Allowable stress.

Code of Federal Regulations, 2012 CFR

2012-10-01

...: (1) For tank web frames, stringers, or girders of carbon manganese steel or aluminum alloys, meet σB... in appendix A of this part. (c) Tank plating must meet the American Bureau of Shipping's deep tank...

Solving a methodological challenge in work stress evaluation with the Stress Assessment and Research Toolkit (StART): a study protocol.

PubMed

Guglielmi, Dina; Simbula, Silvia; Vignoli, Michela; Bruni, Ilaria; Depolo, Marco; Bonfiglioli, Roberta; Tabanelli, Maria Carla; Violante, Francesco Saverio

2013-06-22

Stress evaluation is a field of strong interest and challenging due to several methodological aspects in the evaluation process. The aim of this study is to propose a study protocol to test a new method (i.e., the Stress Assessment and Research Toolkit) to assess psychosocial risk factors at work. This method addresses several methodological issues (e.g., subjective vs. objective, qualitative vs quantitative data) by assessing work-related stressors using different kinds of data: i) organisational archival data (organisational indicators sheet); ii) qualitative data (focus group); iii) worker perception (questionnaire); and iv) observational data (observational checklist) using mixed methods research. In addition, it allows positive and negative aspects of work to be considered conjointly, using an approach that considers at the same time job demands and job resources. The integration of these sources of data can reduce the theoretical and methodological bias related to stress research in the work setting, allows researchers and professionals to obtain a reliable description of workers' stress, providing a more articulate vision of psychosocial risks, and allows a large amount of data to be collected. Finally, the implementation of the method ensures in the long term a primary prevention for psychosocial risk management in that it aims to reduce or modify the intensity, frequency or duration of organisational demands.

An analysis of fiber-matrix interface failure stresses for a range of ply stress states

NASA Technical Reports Server (NTRS)

Crews, J. H.; Naik, R. A.; Lubowinski, S. J.

1993-01-01

A graphite/bismaleimide laminate was prepared without the usual fiber treatment and was tested over a wide range of stress states to measure its ply cracking strength. These tests were conducted using off-axis flexure specimens and produced fiber-matrix interface failure data over a correspondingly wide range of interface stress states. The absence of fiber treatment, weakened the fiber-matrix interfaces and allowed these tests to be conducted at load levels that did not yield the matrix. An elastic micromechanics computer code was used to calculate the fiber-matrix interface stresses at failure. Two different fiber-array models (square and diamond) were used in these calculations to analyze the effects of fiber arrangement as well as stress state on the critical interface stresses at failure. This study showed that both fiber-array models were needed to analyze interface stresses over the range of stress states. A linear equation provided a close fit to these critical stress combinations and, thereby, provided a fiber-matrix interface failure criterion. These results suggest that prediction procedures for laminate ply cracking can be based on micromechanics stress analyses and appropriate fiber-matrix interface failure criteria. However, typical structural laminates may require elastoplastic stress analysis procedures that account for matrix yielding, especially for shear-dominated ply stress states.

Distinguish self- and hetero-perceived stress through behavioral imaging and physiological features.

PubMed

Spodenkiewicz, Michel; Aigrain, Jonathan; Bourvis, Nadège; Dubuisson, Séverine; Chetouani, Mohamed; Cohen, David

2018-03-02

Stress reactivity is a complex phenomenon associated to multiple and multimodal expressions. Response to stressors has an obvious survival function and may be seen as an internal regulation to adapt to threat or danger. The intensity of this internal response can be assessed as the self-perception of the stress response. In species with social organization, this response also serves a communicative function, so-called hetero-perception. Our study presents multimodal stress detection assessment - a new methodology combining behavioral imaging and physiological monitoring for analyzing stress from these two perspectives. The system is based on automatic extraction of 39 behavioral (2D+3D video recording) and 62 physiological (Nexus-10 recording) features during a socially evaluated mental arithmetic test. The analysis with machine learning techniques for automatic classification using Support Vector Machine (SVM) show that self-perception and hetero-perception of social stress are both close but different phenomena: self-perception was significantly correlated with hetero-perception but significantly differed from it. Also, assessing stress with SVM through multimodality gave excellent classification results (F1 score values: 0.9±0.012 for hetero-perception and 0.87±0.021 for self-perception). In the best selected feature subsets, we found some common behavioral and physiological features that allow classification of both self- and hetero-perceived stress. However, we also found the contributing features for automatic classifications had opposite distributions: self-perception classification was mainly based on physiological features and hetero-perception was mainly based on behavioral features. Copyright © 2017. Published by Elsevier Inc.

Uncertainties in obtaining high reliability from stress-strength models

NASA Technical Reports Server (NTRS)

Neal, Donald M.; Matthews, William T.; Vangel, Mark G.

1992-01-01

There has been a recent interest in determining high statistical reliability in risk assessment of aircraft components. The potential consequences are identified of incorrectly assuming a particular statistical distribution for stress or strength data used in obtaining the high reliability values. The computation of the reliability is defined as the probability of the strength being greater than the stress over the range of stress values. This method is often referred to as the stress-strength model. A sensitivity analysis was performed involving a comparison of reliability results in order to evaluate the effects of assuming specific statistical distributions. Both known population distributions, and those that differed slightly from the known, were considered. Results showed substantial differences in reliability estimates even for almost nondetectable differences in the assumed distributions. These differences represent a potential problem in using the stress-strength model for high reliability computations, since in practice it is impossible to ever know the exact (population) distribution. An alternative reliability computation procedure is examined involving determination of a lower bound on the reliability values using extreme value distributions. This procedure reduces the possibility of obtaining nonconservative reliability estimates. Results indicated the method can provide conservative bounds when computing high reliability. An alternative reliability computation procedure is examined involving determination of a lower bound on the reliability values using extreme value distributions. This procedure reduces the possibility of obtaining nonconservative reliability estimates. Results indicated the method can provide conservative bounds when computing high reliability.

Stress rotation along pre-Cenozoic basement structures

NASA Astrophysics Data System (ADS)

Reiter, K.; Heidbach, O.; Henk, A.

2017-12-01

The in-situ stress state of the Earth's crust is under investigation since decades for both, scientific and economic purposes. Several methods have been established to indicate the contemporary orientation of the maximum compressive horizontal stress (SHmax). It is assumed that the same forces that drive plate motion are the first order stress sources and one could presume that SHmax is always parallel to plate motion, which is the case for some regions. However, deviations from this general trend occur in many regions. Therefore, second and third order sources of stress have been identified that potentially cause regional and local stress rotation with respect to the long wave-length trend imposed by plate tectonic forces. One group of such subordinate stress sources are lateral heterogeneities based on structures, petrothermal or petrophysical properties. The World Stress Map (WSM) project compiles systematically data records of the present day SHmax orientation. The increasing amount of stress orientation data allows to investigate areas with consistent stress rotation, divergent to the regional stress pattern. In our work we analyse the stress pattern variability and its causes beneath Germany. In the Molasse Basin in the Alpine foreland the SHmax orientation is perpendicular to the Alpine front as a consequence of gravitational potential energy of the orogen. SHmax is oriented in N-S direction in the central Alpine foreland and within the North German Basin. Between both, within the Mid-German Crystalline High, SHmax is divergent oriented in SE-NW direction. Neither gravitational potential energy nor petrothermal effects can be indicated as stress source. But when comparing the stress pattern with the Variscan basement structures it is obvious that SHmax is perpendicular oriented to this Palaeozoic basement structures. Therefore, petrophysical heterogeneities can be expected as reason for the observed stress rotation. Two assumptions can be made for the Mid

An allowable cladding peak temperature for spent nuclear fuels in interim dry storage

NASA Astrophysics Data System (ADS)

Cha, Hyun-Jin; Jang, Ki-Nam; Kim, Kyu-Tae

2018-01-01

Allowable cladding peak temperatures for spent fuel cladding integrity in interim dry storage were investigated, considering hydride reorientation and mechanical property degradation behaviors of unirradiated and neutron irradiated Zr-Nb cladding tubes. Cladding tube specimens were heated up to various temperatures and then cooled down under tensile hoop stresses. Cool-down specimens indicate that higher heat-up temperature and larger tensile hoop stress generated larger radial hydride precipitation and smaller tensile strength and plastic hoop strain. Unirradiated specimens generated relatively larger radial hydride precipitation and plastic strain than did neutron irradiated specimens. Assuming a minimum plastic strain requirement of 5% for cladding integrity maintenance in interim dry storage, it is proposed that a cladding peak temperature during the interim dry storage is to keep below 250 °C if cladding tubes are cooled down to room temperature.

Effectiveness of patient empowerment over stress related to knee arthroplasty surgery.

PubMed

Garzón-Rey, Jorge Mario; Arza-Valdés, Adriana; Nuevo-Gayoso, Montserrat; Aguiló, Jordi

This study aims to show evidence of the Empowerment Session's effectiveness through measurements of surgery related emotional stress before and after this session. The study was performed on 41 patients with knee arthroplasty surgery prescription by measuring the evolution of their emotional stress generated by surgery expectative, during the empowerment session. Two sets of measurements per patient were performed, before and after the empowerment session. Each set consisted of recording an electrocardiogram for 10min while the patients were seated and then applying two standard psychometric tests: State-Trait Anxiety Inventory test and Visual Analog Stress test. Differences in emotional stress were analyzed using psychometric tests and heart rate variability (HRV) analysis as stress biomarkers. Psychometric stress measurement shows a 17.8% reduction in stress according to the total stress scale value, and a 41.9% reduction in stress between test results before and after the session. Mean heart rate values increased by 7.4% with respect to the initial values, very low frequency power and total power also change in value suggesting more sympathetic and less parasympathetic activity. Both psychological and physiological measurements suggest the effectiveness of the empowerment session due to a significant increase in the wellness state of patients. Additionally, the correlation between psychometric tests and HRV indices demonstrates that both emotional stress indicators could be used as feedback on the empowerment sessions or as a reference to enhance surgical outcomes. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

Radiocardiographic measurement of minimum central transit times by means of indium-113m-DTPA and of a 8-crystal radiocardiograph (Gamma Retina VI). Comparative investigations on non-trained and athletics in repose and after stress (in German)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knapp, W.H.

The minimum cardiac transit times (MTT's) at rest and following sub- maximum stresses were measured in 97 individual examinations of untrained persons and high performance athletes. It turned out that there is a strong dependence on cardiac frequency of the MTT's. This relation can be described quite satisfactorily by a hyperbolic function and in this way allows a frequency correction to be made of the MTT's. The MTT's standardized in this way (MTT.f values) represent the quotient of the end diastolic segment volume/beat volume. In the whole lesser circulatory system almost identical MTT.f values were found for the two groupsmore » under comparison at rest and following stress. In the ventricles, however, and especially so in the left ventricle, the MTT.f values were clearly higher with athletes than with untrained persons, but they strongly decreased after stresses, while the respective values remained almost constant in ordinary persons. (orig./RF)« less

Finite element method for analysis of stresses arising in the skull after external loading in cranio-orbital fractures.

PubMed

Wanyura, Hubert; Kowalczyk, Piotr; Bossak, Maciej; Samolczyk-Wanyura, Danuta; Stopa, Zygmunt

2012-01-01

The craniofacial skeleton remains not fully recognised as far as its mechanical resistance properties are concerned. Heretofore, the only available information on the mechanism of cranial bone fractures came from clinical observations, since the clinical evaluation in a living individual is practically impossible. It seems crucial to implement computer methods of virtual research into clinical practice. Such methods, which have long been used in the technical sciences, may either confirm or disprove previous observations. The aim of the study was to identify the areas of stress concentrations caused by external loads, which can lead to cranio-orbital fractures (COF), by the finite element method (FEM). For numerical analysis, a three-dimensional commercially available geometrical model of the skull was used which was imported into software of FEM. Computations were performed with ANSYS 12.1 Static Structural module. The loads were applied laterally to the frontal squama, the zygomatic process and partly to the upper orbital rim to locate dangerous concentration of stresses potentially resulting in COF. Changes in the area of force application revealed differences in values, quality and the extent of the stress distribution. Depending on the area of force application the following parameters would change: the value and area of stresses characteristic of COF. The distribution of stresses obtained in this study allowed definition of both the locations most vulnerable to fracture and sites from which fractures may originate or propagate.

Character strengths, social anxiety, and physiological stress reactivity.

PubMed

Li, Tingting; Duan, Wenjie; Guo, Pengfei

2017-01-01

In this paper, the effects of character strengths on the physiological reactivity to social anxiety induced by the Trier Social Stress Task were reported. On the basis of their scores in the Chinese Virtues Questionnaire, 30 college students were assigned to either high- ( n  = 15) or low-character-strength ( n  = 15) groups. Their psychological stress and physiological data across three laboratory stages (namely, baseline, stress exposure, and post-stress) were collected. Results indicated that individuals with high character strengths exhibited rapid cardiovascular recovery from baseline to post-stress even if high- and low-character-strength groups showed similar patterns of cardiovascular arousal in response to the stress at baseline and stress exposure. These results prove that character strengths are stress-defense factors that allow for psychological and physiological adaptation to stress.

30 CFR 1206.112 - What adjustments and transportation allowances apply when I value oil production from my lease...

Code of Federal Regulations, 2011 CFR

2011-07-01

... representative crude oil at the market center after making the quality adjustments described in paragraphs (a... in value between your lease and the appropriate ONRR-recognized market center at which the ANS spot... this section explains how you adjust the value between the lease and the market center, and paragraph...

The effect of stress on limestone permeability and its effective stress behavior

NASA Astrophysics Data System (ADS)

Meng, F.; Baud, P.; Ge, H.; Wong, T. F.

2017-12-01

The evolution of permeability and its effective stress behavior is related to inelastic deformation and failure mode. This was investigated in Indiana and Purbeck limestones with porosities of 18% and 13%, respectively. Hydrostatic and triaxial compression tests were conducted at room temperature on water-saturated samples at pore pressure of 5 MPa and confining pressures up to 90 MPa. Permeability was measured using steady flow at different stages of deformation. For Indiana limestone, under hydrostatic loading pore collapse initiated at critical pressure P* 55 MPa with an accelerated reduction of permeability by 1/2. At a confinement of 35 MPa and above, shear-enhanced compaction initiated at critical stress C*, beyond which permeability reduction up to a factor of 3 was observed. At a confinement of 15 MPa and below, dilatancy initiated at critical stress C', beyond which permeability continued to decrease, with a negative correlation between porosity and permeability changes. Purbeck limestone showed similar evolution of permeability. Microstructural and mercury porosimetry data showed that pore size distribution in both Indiana and Purbeck limestones is bimodal, with significant proportions of macropores and micropores. The effective stress behaviour of a limestone with dual porosity is different from the prediction for a microscopically homogeneous assemblage, in that its effective stress coefficients for permeability and porosity change may attain values significantly >1. Indeed this was confirmed by our measurements (at confining pressures of 7-15 MPa and pore pressures of 1-3 MPa) in samples that had not been deformed inelastically. We also investigated the behavior in samples hydrostatically and triaxially compacted to beyond the critical stresses P* and C*, respectively. Experimental data for these samples consistently showed effective stress coefficients for both permeability and porosity change with values <1. Thus the effective stress behavior in an

On relating apparent stress to the stress causing earthquake fault slip

USGS Publications Warehouse

McGarr, A.

1999-01-01

Apparent stress ??a is defined as ??a = ??????, where ???? is the average shear stress loading the fault plane to cause slip and ?? is the seismic efficiency, defined as Ea/W, where Ea is the energy radiated seismically and W is the total energy released by the earthquake. The results of a recent study in which apparent stresses of mining-induced earthquakes were compared to those measured for laboratory stick-slip friction events led to the hypothesis that ??a/???? ??? 0.06. This hypothesis is tested here against a substantially augmented data set of earthquakes for which ???? can be estimated, mostly from in situ stress measurements, for comparison with ??a. The expanded data set, which includes earthquakes artificially triggered at a depth of 9 km in the German Kontinentales Tiefbohrprogramm der Bundesrepublik Deutschland (KTB) borehole and natural tectonic earthquakes, covers a broad range of hypocentral depths, rock types, pore pressures, and tectonic settings. Nonetheless, over ???14 orders of magnitude in seismic moment, apparent stresses exhibit distinct upper bounds defined by a maximum seismic efficiency of ???0.06, consistent with the hypothesis proposed before. This behavior of ??a and ?? can be expressed in terms of two parameters measured for stick-slip friction events in the laboratory: the ratio of the static to the dynamic coefficient of friction and the fault slip overshoot. Typical values for these two parameters yield seismic efficiencies of ???0.06. In contrast to efficiencies for laboratory events for which ?? is always near 0.06, those for earthquakes tend to be less than this bounding value because Ea for earthquakes is usually underestimated due to factors such as band-limited recording. Thus upper bounds on ??a/???? appear to be controlled by just a few fundamental aspects of frictional stick-slip behavior that are common to shallow earthquakes everywhere. Estimates of ???? from measurements of ??a for suites of earthquakes, using ??a

Identification of stress biomarkers for drought and increased soil temperature in seedlings of European beech ( Fagus sylvatica )

DOE Office of Scientific and Technical Information (OSTI.GOV)

Popović, Milica; Gregori, Marco; Vodnik, Dominik

Drought is an environmental stress that impacts plant productivity. Projections show both an increase in intense rain events and a reduction in the number of rain days, conditions that leads to increased risk of drought. Consequently, the identification of molecular biomarkers suitable for evaluating the impact of water deprivation conditions on forest plant seedlings is of significant value for monitoring purposes and forest management. In this study, we evaluated a biochemical methodology for the assessment of drought stress coupled with variable soil temperature in European beech (Fagus sylvatica L.) seedlings by analyzing a set of metabolites and enzymes involved inmore » free radical scavenging and cell wall synthesis. The results indicate that the specific activities and isoform profile of superoxide dismutases and glutathione peroxidases together with the variation of phenolic compounds enable discrimination between seedlings with different degrees of photosynthetic activity. This approach represents a promising platform for the assessment of drought stress in forest trees and could serve for enhancing selection and breeding practices, allowing for plants that are more tolerant of abiotic stress.« less

Tensile stress-strain behavior of graphite/epoxy laminates

NASA Technical Reports Server (NTRS)

Garber, D. P.

1982-01-01

The tensile stress-strain behavior of a variety of graphite/epoxy laminates was examined. Longitudinal and transverse specimens from eleven different layups were monotonically loaded in tension to failure. Ultimate strength, ultimate strain, and strss-strain curves wee obtained from four replicate tests in each case. Polynominal equations were fitted by the method of least squares to the stress-strain data to determine average curves. Values of Young's modulus and Poisson's ratio, derived from polynomial coefficients, were compared with laminate analysis results. While the polynomials appeared to accurately fit the stress-strain data in most cases, the use of polynomial coefficients to calculate elastic moduli appeared to be of questionable value in cases involving sharp changes in the slope of the stress-strain data or extensive scatter.

Forecasting the Value of Training

ERIC Educational Resources Information Center

Basarab, Dave

2011-01-01

The Predictive Evaluation (PE) model is a training and evaluation approach with the element of prediction. PE allows trainers and business leaders to predict the results, value, intention, adoption, and impact of training, allowing them to make smarter, more strategic training and evaluation investments. PE is invaluable for companies that…

Maternal Active Mastication during Prenatal Stress Ameliorates Prenatal Stress-Induced Lower Bone Mass in Adult Mouse Offspring.

PubMed

Azuma, Kagaku; Ogura, Minori; Kondo, Hiroko; Suzuki, Ayumi; Hayashi, Sakurako; Iinuma, Mitsuo; Onozuka, Minoru; Kubo, Kin-Ya

2017-01-01

Chronic psychological stress is a risk factor for osteoporosis. Maternal active mastication during prenatal stress attenuates stress response. The aim of this study is to test the hypothesis that maternal active mastication influences the effect of prenatal stress on bone mass and bone microstructure in adult offspring. Pregnant ddY mice were randomly divided into control, stress, and stress/chewing groups. Mice in the stress and stress/chewing groups were placed in a ventilated restraint tube for 45 minutes, 3 times a day, and was initiated on day 12 of gestation and continued until delivery. Mice in the stress/chewing group were allowed to chew a wooden stick during the restraint stress period. The bone response of 5-month-old male offspring was evaluated using quantitative micro-CT, bone histomorphometry, and biochemical markers. Prenatal stress resulted in significant decrease of trabecular bone mass in both vertebra and distal femur of the offspring. Maternal active mastication during prenatal stress attenuated the reduced bone formation and increased bone resorption, improved the lower trabecular bone volume and bone microstructural deterioration induced by prenatal stress in the offspring. These findings indicate that maternal active mastication during prenatal stress can ameliorate prenatal stress-induced lower bone mass of the vertebra and femur in adult offspring. Active mastication during prenatal stress in dams could be an effective coping strategy to prevent lower bone mass in their offspring.

Solving a methodological challenge in work stress evaluation with the Stress Assessment and Research Toolkit (StART): a study protocol

PubMed Central

2013-01-01

Background Stress evaluation is a field of strong interest and challenging due to several methodological aspects in the evaluation process. The aim of this study is to propose a study protocol to test a new method (i.e., the Stress Assessment and Research Toolkit) to assess psychosocial risk factors at work. Design This method addresses several methodological issues (e.g., subjective vs. objective, qualitative vs quantitative data) by assessing work-related stressors using different kinds of data: i) organisational archival data (organisational indicators sheet); ii) qualitative data (focus group); iii) worker perception (questionnaire); and iv) observational data (observational checklist) using mixed methods research. In addition, it allows positive and negative aspects of work to be considered conjointly, using an approach that considers at the same time job demands and job resources. Discussion The integration of these sources of data can reduce the theoretical and methodological bias related to stress research in the work setting, allows researchers and professionals to obtain a reliable description of workers’ stress, providing a more articulate vision of psychosocial risks, and allows a large amount of data to be collected. Finally, the implementation of the method ensures in the long term a primary prevention for psychosocial risk management in that it aims to reduce or modify the intensity, frequency or duration of organisational demands. PMID:23799950

MV-OPES: Multivalued-Order Preserving Encryption Scheme: A Novel Scheme for Encrypting Integer Value to Many Different Values

NASA Astrophysics Data System (ADS)

Kadhem, Hasan; Amagasa, Toshiyuki; Kitagawa, Hiroyuki

Encryption can provide strong security for sensitive data against inside and outside attacks. This is especially true in the “Database as Service” model, where confidentiality and privacy are important issues for the client. In fact, existing encryption approaches are vulnerable to a statistical attack because each value is encrypted to another fixed value. This paper presents a novel database encryption scheme called MV-OPES (Multivalued — Order Preserving Encryption Scheme), which allows privacy-preserving queries over encrypted databases with an improved security level. Our idea is to encrypt a value to different multiple values to prevent statistical attacks. At the same time, MV-OPES preserves the order of the integer values to allow comparison operations to be directly applied on encrypted data. Using calculated distance (range), we propose a novel method that allows a join query between relations based on inequality over encrypted values. We also present techniques to offload query execution load to a database server as much as possible, thereby making a better use of server resources in a database outsourcing environment. Our scheme can easily be integrated with current database systems as it is designed to work with existing indexing structures. It is robust against statistical attack and the estimation of true values. MV-OPES experiments show that security for sensitive data can be achieved with reasonable overhead, establishing the practicability of the scheme.

Possible relationship between Seismic Electric Signals (SES) lead time and earthquake stress drop

PubMed Central

DOLOGLOU, Elizabeth

2008-01-01

Stress drop values for fourteen large earthquakes with MW ≥ 5.4 which occurred in Greece during the period 1983–2007 are available. All these earthquakes were preceded by Seismic Electric Signals (SES). An attempt has been made to investigate possible correlation between their stress drop values and the corresponding SES lead times. For the stress drop, we considered the Brune stress drop, ΔσB, estimated from far field body wave displacement source spectra and ΔσSB derived from the strong motion acceleration response spectra. The results show a relation may exist between Brune stress drop, ΔσB, and lead time which implies that earthquakes with higher stress drop values are preceded by SES with shorter lead time. PMID:18941291

Character strengths, social anxiety, and physiological stress reactivity

PubMed Central

2017-01-01

In this paper, the effects of character strengths on the physiological reactivity to social anxiety induced by the Trier Social Stress Task were reported. On the basis of their scores in the Chinese Virtues Questionnaire, 30 college students were assigned to either high- (n = 15) or low-character-strength (n = 15) groups. Their psychological stress and physiological data across three laboratory stages (namely, baseline, stress exposure, and post-stress) were collected. Results indicated that individuals with high character strengths exhibited rapid cardiovascular recovery from baseline to post-stress even if high- and low-character-strength groups showed similar patterns of cardiovascular arousal in response to the stress at baseline and stress exposure. These results prove that character strengths are stress-defense factors that allow for psychological and physiological adaptation to stress. PMID:28584721

b values and ω−γ seismic source models: Implications for tectonic stress variations along active crustal fault zones and the estimation of high-frequency strong ground motion

USGS Publications Warehouse

Hanks, Thomas C.

1979-01-01

In this study the tectonic stress along active crustal fault zones is taken to be of the form , where  is the average tectonic stress at depth y and Δσp(x, y) is a seismologically observable, essentially random function of both fault plane coordinates; the stress differences arising in the course of crustal faulting are derived from Δσp(x, y). Empirically known frequency of occurrence statistics, moment-magnitude relationships, and the constancy of earthquake stress drops may be used to infer that the number of earthquakes N of dimension ≥r is of the form N ∼ 1/r2 and that the spectral composition of Δσp(x, y) is of the form , where  is the two-dimensional Fourier transform of Δσp(x, y) expressed in radial wave number k. The γ = 2 model of the far-field shear wave displacement spectrum is consistent with the spectral composition , provided that the number of contributions to the spectral representation of the radiated field at frequency ƒ goes as (k/k0)2, consistent with the quasi-static frequency of occurrence relation N ∼ 1/r2;k0 is a reference wave number associated with the reciprocal source dimension. Separately, a variety of seismologic observations suggests that the γ = 2 model is the one generally, although certainly not always, applicable to the high-frequency spectral decay of the far-field radiation of earthquakes. In this framework, then, b values near 1, the general validity of the γ = 2 model, and the constancy of earthquake stress drops independent of size are all related to the average spectral composition of. Should one of these change as a result of premonitory effects leading to failure, as has been specifically proposed for b values, it seems likely that one or all of the other characteristics will change as well from their normative values. Irrespective of these associations, the far-field, high-frequency shear radiation for the γ = 2 model in the presence of anelastic attenuation may be interpreted as

Principals' Leadership Behaviour: Values-Based, Contingent or Both?

ERIC Educational Resources Information Center

Warwas, Julia

2015-01-01

Purpose: Concepts of values-based leadership posit that school principals' professional practice must be informed by values to ensure coherently purposeful activities. Contingency models stress the contextual dependency of professional practice and the need to match activities to local opportunities and constraints. The purpose of this paper is to…

Mean velocities and Reynolds stresses upstream of a simulated wing-fuselage juncture

NASA Technical Reports Server (NTRS)

Mcmahon, H.; Hubbartt, J.; Kubendran, L. R.

1983-01-01

Values of three mean velocity components and six turbulence stresses measured in a turbulent shear layer upstream of a simulated wing-fuselage juncture and immediately downstream of the start of the juncture are presented nd discussed. Two single-sensor hot-wire probes were used in the measurements. The separated region just upstream of the wing contains an area of reversed flow near the fuselage surface where the turbulence level is high. Outside of this area the flow skews as it passes around the body, and in this skewed region the magnitude and distribution of the turbulent normal and shear stresses within the shear layer are modified slightly by the skewing and deceleration of the flow. A short distance downstream of the wing leading edge the secondary flow vortext is tightly rolled up and redistributes both mean flow and turbulence in the juncture. The data acquisition technique employed here allows a hot wire to be used in a reversed flow region to indicate flow direction.

Assessing corn water stress using spectral reflectance

NASA Astrophysics Data System (ADS)

Mefford, Brenna S.

stress as indicated by good R2 values (Nratio = 0.53, G ratio=0.46, Oratio=0.49) and low RMSE values (Nratio = 0.076, Gratio=0.062, Oratio=0.076) when compared to Ks. Therefore it can be concluded that corn spectral reflectance is sensitive to water stress. In order to use spectral reflectance to manage crop water stress an irrigation trigger point of 0.93 for the vegetation ratios was determined. These results were validated using data collected by a MSR5 multispectral sensor in an adjacent field (SWIIM Field). The results from the second field proved better than in the main field giving higher R 2 values (Nratio = 0.66, Gratio = 0.63, Oratio = 0.66), and lower RMSE values (Nratio = 0.043, Gratio = 0.036, Oratio = 0.043) between Ks and the vegetation indices. SWIIM field further validated the results that spectral reflectance can be used to monitor corn water stress.

Accounting for energy and protein reserve changes in predicting diet-allowable milk production in cattle.

PubMed

Tedeschi, L O; Seo, S; Fox, D G; Ruiz, R

2006-12-01

Current ration formulation systems used to formulate diets on farms and to evaluate experimental data estimate metabolizable energy (ME)-allowable and metabolizable protein (MP)-allowable milk production from the intake above animal requirements for maintenance, pregnancy, and growth. The changes in body reserves, measured via the body condition score (BCS), are not accounted for in predicting ME and MP balances. This paper presents 2 empirical models developed to adjust predicted diet-allowable milk production based on changes in BCS. Empirical reserves model 1 was based on the reserves model described by the 2001 National Research Council (NRC) Nutrient Requirements of Dairy Cattle, whereas empirical reserves model 2 was developed based on published data of body weight and composition changes in lactating dairy cows. A database containing 134 individually fed lactating dairy cows from 3 trials was used to evaluate these adjustments in milk prediction based on predicted first-limiting ME or MP by the 2001 Dairy NRC and Cornell Net Carbohydrate and Protein System models. The analysis of first-limiting ME or MP milk production without adjustments for BCS changes indicated that the predictions of both models were consistent (r(2) of the regression between observed and model-predicted values of 0.90 and 0.85), had mean biases different from zero (12.3 and 5.34%), and had moderate but different roots of mean square errors of prediction (5.42 and 4.77 kg/d) for the 2001 NRC model and the Cornell Net Carbohydrate and Protein System model, respectively. The adjustment of first-limiting ME- or MP-allowable milk to BCS changes improved the precision and accuracy of both models. We further investigated 2 methods of adjustment; the first method used only the first and last BCS values, whereas the second method used the mean of weekly BCS values to adjust ME- and MP-allowable milk production. The adjustment to BCS changes based on first and last BCS values was more accurate

Composite-Material Point-Stress Analysis

NASA Technical Reports Server (NTRS)

Spears, F., S.

1982-01-01

PSANAL computes composite-laminate elastic and thermal properties and allowable load levels for any combination of applied membrane and bending loads occurring at a point. Basic linear orthotropic stress/ strain relationships and standard composite-laminate theory formulas are utilized.

Teacher Stress Inventory: validation of the Greek version and perceived stress levels among 3,447 educators

PubMed Central

Kourmousi, Ntina; Darviri, Christina; Varvogli, Liza; Alexopoulos, Evangelos C

2015-01-01

Background The Teacher Stress Inventory (TSI) is an instrument for measuring occupational stress in teachers. This study aimed to translate and adapt it for use in Greece, and then assess its reliability and validity. Methods The Greek versions of the TSI and the 14-item Perceived Stress Scale (PSS-14) were posted on all Greek educators’ official sites during May 2012. A nationwide sample of 3,447 teachers of all levels and specialties completed the questionnaires via the Internet. Reliability was determined by the calculation of Cronbach’s alpha coefficient. Confirmatory factor analysis was conducted and validity was further examined by investigating the correlation of the TSI with the PSS-14 and their association with demographics and work-related factors. Results Satisfactory Cronbach’s alpha values (above 0.70) were found for all TSI dimensions. Confirmatory factor analysis confirmed the two-factor construct of TSI (root mean square error of approximation, comparative fit index, and goodness-of-fit index values were 0.079, 0.956, and 0.951, respectively), confirming the pre-established theory for the two latent variables, Stress Sources and Stress Manifestations. Significant correlations were found between TSI subscales, PSS-14 sex, age, lack of support, and students’ difficulties. Conclusion The Greek version of the TSI was found to have satisfactory psychometric properties, and its use for assessing stress in Greek teachers is warranted. PMID:25834469

Teacher Stress Inventory: validation of the Greek version and perceived stress levels among 3,447 educators.

PubMed

Kourmousi, Ntina; Darviri, Christina; Varvogli, Liza; Alexopoulos, Evangelos C

2015-01-01

The Teacher Stress Inventory (TSI) is an instrument for measuring occupational stress in teachers. This study aimed to translate and adapt it for use in Greece, and then assess its reliability and validity. The Greek versions of the TSI and the 14-item Perceived Stress Scale (PSS-14) were posted on all Greek educators' official sites during May 2012. A nationwide sample of 3,447 teachers of all levels and specialties completed the questionnaires via the Internet. Reliability was determined by the calculation of Cronbach's alpha coefficient. Confirmatory factor analysis was conducted and validity was further examined by investigating the correlation of the TSI with the PSS-14 and their association with demographics and work-related factors. Satisfactory Cronbach's alpha values (above 0.70) were found for all TSI dimensions. Confirmatory factor analysis confirmed the two-factor construct of TSI (root mean square error of approximation, comparative fit index, and goodness-of-fit index values were 0.079, 0.956, and 0.951, respectively), confirming the pre-established theory for the two latent variables, Stress Sources and Stress Manifestations. Significant correlations were found between TSI subscales, PSS-14 sex, age, lack of support, and students' difficulties. The Greek version of the TSI was found to have satisfactory psychometric properties, and its use for assessing stress in Greek teachers is warranted.

Oxidative stress parameters in localized scleroderma patients.

PubMed

Kilinc, F; Sener, S; Akbaş, A; Metin, A; Kirbaş, S; Neselioglu, S; Erel, O

2016-11-01

Localized scleroderma (LS) (morphea) is a chronic, inflammatory skin disease with unknown cause that progresses with sclerosis in the skin and/or subcutaneous tissues. Its pathogenesis is not completely understood. Oxidative stress is suggested to have a role in the pathogenesis of localized scleroderma. We have aimed to determine the relationship of morphea lesions with oxidative stress. The total oxidant capacity (TOC), total antioxidant capacity (TAC), paroxonase (PON) and arylesterase (ARES) activity parameters of PON 1 enzyme levels in the serum were investigated in 13 LS patients (generalized and plaque type) and 13 healthy controls. TOC values of the patient group were found higher than the TOC values of the control group (p < 0.01). ARES values of the patient group was found to be higher than the control group (p < 0.0001). OSI was significantly higher in the patient group when compared to the control (p < 0.005). Oxidative stress seems to be effective in the pathogenesis. ARES levels have increased in morphea patients regarding to the oxidative stress and its reduction. Further controlled studies are required in wider series.

Affective stress responses during leisure time: Validity evaluation of a modified version of the Stress-Energy Questionnaire.

PubMed

Hadžibajramović, Emina; Ahlborg, Gunnar; Håkansson, Carita; Lundgren-Nilsson, Åsa; Grimby-Ekman, Anna

2015-12-01

Psychosocial stress at work is one of the most important factors behind increasing sick-leave rates. In addition to work stressors, it is important to account for non-work-related stressors when assessing stress responses. In this study, a modified version of the Stress-Energy Questionnaire (SEQ), the SEQ during leisure time (SEQ-LT) was introduced for assessing the affective stress response during leisure time. The aim of this study was to investigate the internal construct validity of the SEQ-LT. A second aim was to define the cut-off points for the scales, which could indicate high and low levels of leisure-time stress and energy, respectively. Internal construct validity of the SEQ-LT was evaluated using a Rasch analysis. We examined the unidimensionality and other psychometric properties of the scale by the fit to the Rasch model. A criterion-based approach was used for classification into high and low stress/energy levels. The psychometric properties of the stress and energy scales of the SEQ-LT were satisfactory, having accommodated for local dependency. The cut-off point for low stress was proposed to be in the interval between 2.45 and 3.02 on the Rasch metric score; while for high stress, it was between 3.65 and 3.90. The suggested cut-off points for the low and high energy levels were values between 1.73-1.97 and 2.66-3.08, respectively. The stress and energy scale of the SEQ-LT satisfied the measurement criteria defined by the Rasch analysis and it provided a useful tool for non-work-related assessment of stress responses. We provide guidelines on how to interpret the scale values. © 2015 the Nordic Societies of Public Health.

Monolithic Flexure Pre-Stressed Ultrasonic Horns

NASA Technical Reports Server (NTRS)

Sherrit, Stewart; Bao, Xiaoqi; Badescu, Mircea; Bar-Cohen, Yoseph; Allen, Phillip Grant

2011-01-01

High-power ultrasonic actuators are generally assembled with a horn, backing, stress bolt, piezoelectric rings, and electrodes. The manufacturing process is complex, expensive, difficult, and time-consuming. The internal stress bolt needs to be insulated and presents a potential internal discharge point, which can decrease actuator life. Also, the introduction of a center hole for the bolt causes many failures, reducing the throughput of the manufactured actuators. A new design has been developed for producing ultrasonic horn actuators. This design consists of using flexures rather than stress bolts, allowing one to apply pre-load to the piezoelectric material. It also allows one to manufacture them from a single material/plate, rapid prototype them, or make an array in a plate or 3D structure. The actuator is easily assembled, and application of pre-stress greater than 25 MPa was demonstrated. The horn consists of external flexures that eliminate the need for the conventional stress bolt internal to the piezoelectric, and reduces the related complexity. The stress bolts are required in existing horns to provide prestress on piezoelectric stacks when driven at high power levels. In addition, the manufacturing process benefits from the amenability to produce horn structures with internal cavities. The removal of the pre-stress bolt removes a potential internal electric discharge point in the actuator. In addition, it significantly reduces the chances of mechanical failure in the piezoelectric stacks that result from the hole surface in conventional piezoelectric actuators. The novel features of this disclosure are: 1. A design that can be manufactured from a single piece of metal using EDM, precision machining, or rapid prototyping. 2. Increased electromechanical coupling of the horn actuator. 3. Higher energy density. 4. A monolithic structure of a horn that consists of an external flexure or flexures that can be used to pre-stress a solid piezoelectric structure

Research on wire rope stress distribution of WR-CVT

NASA Astrophysics Data System (ADS)

Zhang, Wu; Guo, Wei; Zhang, Chuanwei; Lu, Zhengxiong; Xu, Xiaobin

2017-10-01

A wire rope continuously variable transmissions (WR-CVT) has been introduced in the paper, in view of its less research, this paper mainly studied the stress distribution of 6×7+IWS bending wire rope. The results shown that the wire stress is layered distribution in each section, the stress at the outer strand center wire and outer strand side wire was the greatest, the stress value of the outer strand side wire and metal block circular notch is second. As the transmission ratio decreases, the wire stress decreases, which is related to the pulley working radius increases. Compared with the section A1, the stress value on the section A2 is smaller, mainly because the section A2 is not in contact with the metal block or the contact pressure is small. This study provides a basis for the study of fatigue and wears failure of WR-CVT components.

Advanced methodology to determine plant stresses using in-situ spectral data

NASA Astrophysics Data System (ADS)

Polinova, Maria; Brook, Anna; Housh, Mashor

2017-04-01

Fluorescence method in remote sensing has long been a traditional method estimating plant state. Vegetation indices (VIs) are tool for assessment plants' state based on its spectral characteristics. During the last half-century, in this domain were developed many vegetation indices and even more modifications of these indices. Nowadays, visible range across electromagnetic waves allows assessing plants' health and calculating its physical parameters. One of the VI's capabilities is detecting stress in plants. This approach has application in different areas. For discerning external environment (unnatural) stress from features of plant's development most of VIs have border values for greenness and health. This is the reason for these methods to be superficial and insufficient detecting and estimating stresses on the early stages. This limits plays especial importance in agriculture. Late stress detection leads to irreversible damage in crops and yield loss. We propose new principle of VI analysis for determination unnatural stress on early stages. Novelty of this method is common consideration several VIs related to plant's pigmentation: chlorophyll, carotenoids and anthocyanins. We have tasted this method on two agriculture fields: tomatoes and cotton. The goal of study was to determinate water crop stress at its beginning. A single VI shows reactions on emergence growth stage, fruit producing and ripening phase. It was hard to isolate crops' reaction on water from reaction on growth changes. Nevertheless, we have noted that there is correlation between chlorophyll VIs and carotenoid VIs. The correlation strength was depended on stress type. Based on common VIs analysis we were able to identify dryness and over irrigation stress. In addition, we have determine reaction on fertilizers input. Common VIs analysis can improve existing fluorescence method of remote sensing monitoring. It can find application in areas where the early plant's stress detection is very

TDM Status Report: Transportation Allowances

DOT National Transportation Integrated Search

1992-08-01

The status report discusses the following travel allowance programs that provide subsidies to employees in one form or another: transit fare allowances or subsidies; vanpool fare allowances; parking allowances or free parking; and general travel allo...

Measurements of Reynolds stress profiles in unstratified tidal flow

USGS Publications Warehouse

Stacey, M.T.; Monismith, Stephen G.; Burau, J.R.

1999-01-01

In this paper we present a method for measuring profiles of turbulence quantities using a broadband acoustic doppler current profiler (ADCP). The method follows previous work on the continental shelf and extends the analysis to develop estimates of the errors associated with the estimation methods. ADCP data was collected in an unstratified channel and the results of the analysis are compared to theory. This comparison shows that the method provides an estimate of the Reynolds stresses, which is unbiased by Doppler noise, and an estimate of the turbulent kinetic energy (TKE) which is biased by an amount proportional to the Doppler noise. The noise in each of these quantities as well as the bias in the TKE match well with the theoretical values produced by the error analysis. The quantification of profiles of Reynolds stresses simultaneous with the measurement of mean velocity profiles allows for extensive analysis of the turbulence of the flow. In this paper, we examine the relation between the turbulence and the mean flow through the calculation of u*, the friction velocity, and Cd, the coefficient of drag. Finally, we calculate quantities of particular interest in turbulence modeling and analysis, the characteristic lengthscales, including a lengthscale which represents the stream-wise scale of the eddies which dominate the Reynolds stresses. Copyright 1999 by the American Geophysical Union.

Voice stress analysis and evaluation

NASA Astrophysics Data System (ADS)

Haddad, Darren M.; Ratley, Roy J.

2001-02-01

Voice Stress Analysis (VSA) systems are marketed as computer-based systems capable of measuring stress in a person's voice as an indicator of deception. They are advertised as being less expensive, easier to use, less invasive in use, and less constrained in their operation then polygraph technology. The National Institute of Justice have asked the Air Force Research Laboratory for assistance in evaluating voice stress analysis technology. Law enforcement officials have also been asking questions about this technology. If VSA technology proves to be effective, its value for military and law enforcement application is tremendous.

Effects of van der Waals Force and Thermal Stresses on Pull-in Instability of Clamped Rectangular Microplates.

PubMed

Batra, Romesh C; Porfiri, Maurizio; Spinello, Davide

2008-02-15

We study the influence of von Karman nonlinearity, van der Waals force, and a athermal stresses on pull-in instability and small vibrations of electrostatically actuated mi-croplates. We use the Galerkin method to develop a tractable reduced-order model for elec-trostatically actuated clamped rectangular microplates in the presence of van der Waals forcesand thermal stresses. More specifically, we reduce the governing two-dimensional nonlineartransient boundary-value problem to a single nonlinear ordinary differential equation. For thestatic problem, the pull-in voltage and the pull-in displacement are determined by solving apair of nonlinear algebraic equations. The fundamental vibration frequency corresponding toa deflected configuration of the microplate is determined by solving a linear algebraic equa-tion. The proposed reduced-order model allows for accurately estimating the combined effectsof van der Waals force and thermal stresses on the pull-in voltage and the pull-in deflectionprofile with an extremely limited computational effort.

Effects of van der Waals Force and Thermal Stresses on Pull-in Instability of Clamped Rectangular Microplates

PubMed Central

Batra, Romesh C.; Porfiri, Maurizio; Spinello, Davide

2008-01-01

We study the influence of von Kármán nonlinearity, van der Waals force, and thermal stresses on pull-in instability and small vibrations of electrostatically actuated microplates. We use the Galerkin method to develop a tractable reduced-order model for electrostatically actuated clamped rectangular microplates in the presence of van der Waals forces and thermal stresses. More specifically, we reduce the governing two-dimensional nonlinear transient boundary-value problem to a single nonlinear ordinary differential equation. For the static problem, the pull-in voltage and the pull-in displacement are determined by solving a pair of nonlinear algebraic equations. The fundamental vibration frequency corresponding to a deflected configuration of the microplate is determined by solving a linear algebraic equation. The proposed reduced-order model allows for accurately estimating the combined effects of van der Waals force and thermal stresses on the pull-in voltage and the pull-in deflection profile with an extremely limited computational effort. PMID:27879752

In situ stress observation in oxide films and how tensile stress influences oxygen ion conduction

PubMed Central

Fluri, Aline; Pergolesi, Daniele; Roddatis, Vladimir; Wokaun, Alexander; Lippert, Thomas

2016-01-01

Many properties of materials can be changed by varying the interatomic distances in the crystal lattice by applying stress. Ideal model systems for investigations are heteroepitaxial thin films where lattice distortions can be induced by the crystallographic mismatch with the substrate. Here we describe an in situ simultaneous diagnostic of growth mode and stress during pulsed laser deposition of oxide thin films. The stress state and evolution up to the relaxation onset are monitored during the growth of oxygen ion conducting Ce0.85Sm0.15O2-δ thin films via optical wafer curvature measurements. Increasing tensile stress lowers the activation energy for charge transport and a thorough characterization of stress and morphology allows quantifying this effect using samples with the conductive properties of single crystals. The combined in situ application of optical deflectometry and electron diffraction provides an invaluable tool for strain engineering in Materials Science to fabricate novel devices with intriguing functionalities. PMID:26912416

Brazed Joints Design and Allowables: Discuss Margins of Safety in Critical Brazed Structures

NASA Technical Reports Server (NTRS)

FLom, Yury

2009-01-01

This slide presentation tutorial discusses margins of safety in critical brazed structures. It reviews: (1) the present situation (2) definition of strength (3) margins of safety (4) design allowables (5) mechanical testing (6) failure criteria (7) design flowchart (8) braze gap (9) residual stresses and (10) delayed failures. This presentation addresses the strength of the brazed joints, the methods of mechanical testing, and our ability to evaluate the margins of safety of the brazed joints as it applies to the design of critical and expensive brazed assemblies.

Hydromechanical behavior of Estaillades carbonate : directional permeability, stress-path and microstructural heterogeneity effects, yield and failure envelopes

NASA Astrophysics Data System (ADS)

Dautriat, J.; Dimanov, A.; Gland, N.; Raphanel, J.

2009-04-01

The influence of stress paths representative of reservoir conditions on the mechanical behavior and the coupled permeability evolutions of a carbonate has been investigated. In order to predict the permeability evolutions under triaxial loading, we have developed a triaxial cell designed to allow the measurements of the permeability in three orthogonal directions, along and transverse to the maximum principal stress direction. A set of core specimens are mechanically loaded following different stress paths characterized by a constant ratio K between horizontal and vertical stress. Our experimental set-up allows the monitoring of the petrophysical and geomechanical parameters during loading, before and post sample damage. The tested rock is an analog reservoir carbonate, the Estaillades Limestone, characterized macroscopically by a porosity around 29% and a moderate permeability around 150mD. From our experimental results, the failure envelope of this carbonate is determined and the evolutions of the directional permeability are examined in the (p',q) diagram. According to the followed stress path, permeability reductions can be limited or drastic. In addition, we have performed microstructural analyses on deformed samples and in-situ observations during loading inside a SEM in order to identify the micromechanisms responsible for the evolutions of porosity and permeability. For instance, we show the importance of local heterogeneities on initiation of damage and of pore collapse. In the near-elastic domain, brittle damage induces limited directional permeability modifications; whereas, at higher stress, depending on the value of K, shear induced dilation or shear induced compaction mechanisms are activated. The highest permeability drop occurred for the hydrostatic compression (K=1), in the compaction regime, characterized by pore collapse mechanisms affecting preferentially the macroporosity. A failure model is proposed and the failure envelope is determined in

Stress Sensitivity and Stress Generation in Social Anxiety Disorder: A Temporal Process Approach

PubMed Central

Farmer, Antonina S.; Kashdan, Todd B.

2015-01-01

Dominant theoretical models of social anxiety disorder (SAD) suggest that people who suffer from function-impairing social fears are likely to react more strongly to social stressors. Researchers have examined the reactivity of people with SAD to stressful laboratory tasks, but there is little knowledge about how stress affects their daily lives. We asked 79 adults from the community, 40 diagnosed with SAD and 39 matched healthy controls, to self-monitor their social interactions, social events, and emotional experiences over two weeks using electronic diaries. These data allowed us to examine associations of social events and emotional well-being both within-day and from one day to the next. Using hierarchical linear modeling, we found all participants to report increases in negative affect and decreases in positive affect and self-esteem on days when they experienced more stressful social events. However, people with SAD displayed greater stress sensitivity, particularly in negative emotion reactions to stressful social events, compared to healthy controls. Groups also differed in how previous days’ events influenced sensitivity to current days’ events. Moreover, we found evidence of stress generation in that the SAD group reported more frequent interpersonal stress, though temporal analyses did not suggest greater likelihood of social stress on days following intense negative emotions. Our findings support the role of heightened social stress sensitivity in SAD, highlighting rigidity in reactions and occurrence of stressful experiences from one day to the next. These findings also shed light on theoretical models of emotions and self-esteem in SAD and present important clinical implications. PMID:25688437

Genetic and Computational Approaches for Studying Plant Development and Abiotic Stress Responses Using Image-Based Phenotyping

NASA Astrophysics Data System (ADS)

Campbell, M. T.; Walia, H.; Grondin, A.; Knecht, A.

2017-12-01

The development of abiotic stress tolerant crops (i.e. drought, salinity, or heat stress) requires the discovery of DNA sequence variants associated with stress tolerance-related traits. However, many traits underlying adaptation to abiotic stress involve a suite of physiological pathways that may be induced at different times throughout the duration of stress. Conventional single-point phenotyping approaches fail to fully capture these temporal responses, and thus downstream genetic analysis may only identify a subset of the genetic variants that are important for adaptation to sub-optimal environments. Although genomic resources for crops have advanced tremendously, the collection of phenotypic data for morphological and physiological traits is laborious and remains a significant bottleneck in bridging the phenotype-genotype gap. In recent years, the availability of automated, image-based phenotyping platforms has provided researchers with an opportunity to collect morphological and physiological traits non-destructively in a highly controlled environment. Moreover, these platforms allow abiotic stress responses to be recorded throughout the duration of the experiment, and have facilitated the use of function-valued traits for genetic analyses in major crops. We will present our approaches for addressing abiotic stress tolerance in cereals. This talk will focus on novel open-source software to process and extract biological meaningful data from images generated from these phenomics platforms. In addition, we will discuss the statistical approaches to model longitudinal phenotypes and dissect the genetic basis of dynamic responses to these abiotic stresses throughout development.

Stress transfer mechanisms at the submicron level for graphene/polymer systems.

PubMed

Anagnostopoulos, George; Androulidakis, Charalampos; Koukaras, Emmanuel N; Tsoukleri, Georgia; Polyzos, Ioannis; Parthenios, John; Papagelis, Konstantinos; Galiotis, Costas

2015-02-25

The stress transfer mechanism from a polymer substrate to a nanoinclusion, such as a graphene flake, is of extreme interest for the production of effective nanocomposites. Previous work conducted mainly at the micron scale has shown that the intrinsic mechanism of stress transfer is shear at the interface. However, since the interfacial shear takes its maximum value at the very edge of the nanoinclusion it is of extreme interest to assess the effect of edge integrity upon axial stress transfer at the submicron scale. Here, we conduct a detailed Raman line mapping near the edges of a monolayer graphene flake that is simply supported onto an epoxy-based photoresist (SU8)/poly(methyl methacrylate) matrix at steps as small as 100 nm. We show for the first time that the distribution of axial strain (stress) along the flake deviates somewhat from the classical shear-lag prediction for a region of ∼ 2 μm from the edge. This behavior is mainly attributed to the presence of residual stresses, unintentional doping, and/or edge effects (deviation from the equilibrium values of bond lengths and angles, as well as different edge chiralities). By considering a simple balance of shear-to-normal stresses at the interface we are able to directly convert the strain (stress) gradient to values of interfacial shear stress for all the applied tensile levels without assuming classical shear-lag behavior. For large flakes a maximum value of interfacial shear stress of 0.4 MPa is obtained prior to flake slipping.

Stress Transfer Mechanisms at the Submicron Level for Graphene/Polymer Systems

PubMed Central

2015-01-01

The stress transfer mechanism from a polymer substrate to a nanoinclusion, such as a graphene flake, is of extreme interest for the production of effective nanocomposites. Previous work conducted mainly at the micron scale has shown that the intrinsic mechanism of stress transfer is shear at the interface. However, since the interfacial shear takes its maximum value at the very edge of the nanoinclusion it is of extreme interest to assess the effect of edge integrity upon axial stress transfer at the submicron scale. Here, we conduct a detailed Raman line mapping near the edges of a monolayer graphene flake that is simply supported onto an epoxy-based photoresist (SU8)/poly(methyl methacrylate) matrix at steps as small as 100 nm. We show for the first time that the distribution of axial strain (stress) along the flake deviates somewhat from the classical shear-lag prediction for a region of ∼2 μm from the edge. This behavior is mainly attributed to the presence of residual stresses, unintentional doping, and/or edge effects (deviation from the equilibrium values of bond lengths and angles, as well as different edge chiralities). By considering a simple balance of shear-to-normal stresses at the interface we are able to directly convert the strain (stress) gradient to values of interfacial shear stress for all the applied tensile levels without assuming classical shear-lag behavior. For large flakes a maximum value of interfacial shear stress of 0.4 MPa is obtained prior to flake slipping. PMID:25644121

Suspensions of Noncolloidal Particles in Yield Stress Fluids: Experimental and Micromechanical Approaches

NASA Astrophysics Data System (ADS)

Mahaut, Fabien; Bertrand, François; Coussot, Philippe; Chateau, Xavier; Ovarlez, Guillaume

2008-07-01

We study experimentally and theoretically the behavior of suspensions of noncolloidal particles in yield stress fluids. We develop procedures and materials that allow focusing on the purely mechanical contribution of the particles to the yield stress fiuid behavior, allowing relating the macroscopic properties of these suspensions to the mechanical properties of the yield stress fluid and the particle volume fraction. We find that the elastic modulus/concentration relationship follows a Krieger-Dougherty law, and show that the yield stress/concentration relationship is related to the elastic modulus/concentration relationship through a very simple law, in agreement with a micromechanical analysis. We finally present evidence for shear-induced migration in the flows of these suspensions.

Prognostic value of stress myocardial perfusion positron emission tomography: results from a multicenter observational registry.

PubMed

Dorbala, Sharmila; Di Carli, Marcelo F; Beanlands, Rob S; Merhige, Michael E; Williams, Brent A; Veledar, Emir; Chow, Benjamin J W; Min, James K; Pencina, Michael J; Berman, Daniel S; Shaw, Leslee J

2013-01-15

The primary objective of this multicenter registry was to study the prognostic value of positron emission tomography (PET) myocardial perfusion imaging (MPI) and the improved classification of risk in a large cohort of patients with suspected or known coronary artery disease (CAD). Limited prognostic data are available for MPI with PET. A total of 7,061 patients from 4 centers underwent a clinically indicated rest/stress rubidium-82 PET MPI, with a median follow-up of 2.2 years. The primary outcome of this study was cardiac death (n = 169), and the secondary outcome was all-cause death (n = 570). Net reclassification improvement (NRI) and integrated discrimination analyses were performed. Risk-adjusted hazard of cardiac death increased with each 10% myocardium abnormal with mildly, moderately, or severely abnormal stress PET (hazard ratio [HR]: 2.3 [95% CI: 1.4 to 3.8; p = 0.001], HR: 4.2 [95% CI: 2.3 to 7.5; p < 0.001], and HR: 4.9 [95% CI: 2.5 to 9.6; p < 0.0001], respectively [normal MPI: referent]). Addition of percent myocardium ischemic and percent myocardium scarred to clinical information (age, female sex, body mass index, history of hypertension, diabetes, dyslipidemia, smoking, angina, beta-blocker use, prior revascularization, and resting heart rate) improved the model performance (C-statistic 0.805 [95% CI: 0.772 to 0.838] to 0.839 [95% CI: 0.809 to 0.869]) and risk reclassification for cardiac death (NRI 0.116 [95% CI: 0.021 to 0.210]), with smaller improvements in risk assessment for all-cause death. In patients with known or suspected CAD, the extent and severity of ischemia and scar on PET MPI provided powerful and incremental risk estimates of cardiac death and all-cause death compared with traditional coronary risk factors. Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Stress situations in dental practice.

PubMed

Bourassa, M; Baylard, J F

1994-01-01

Several studies indicate that stress is inherently present in dental practice. The present study was conducted to help identify the factors underlying this stress and the relative contribution of each factor. A questionnaire presented participating dentists with 52 potentially-stressful situations related to dental practice. Respondents were asked to rate each situation on a five-point scale, using a range of responses that varied from "not stressful" to "exceedingly stressful," and "I don't know" to "not applicable." The present data are based on the ratings given by the 1,332 dentists practicing in Québec who answered the questionnaire (52 per cent). Ten situations received a mean score of greater than 3.0, and were therefore considered as above average stress-producing situations. The majority of these situations could be classified as being related either to dental procedures and office organization or to interpersonal relationships involving patients and/or office personnel. It was found that the older age groups showed significantly less stress for six of the 10 most stressful situations. This study has indicated the specific situations that most frequently lead to stress in dentists. The precise identification of these situations could lead to reduced stress through the elimination of its vague and insidious character. Furthermore, an understanding of the most common stress-causing situations allows the practitioner to take preventive measures to eliminate its damaging effects in the dental practice.

Thermal stresses in layered barium titanate-based semiconductor ceramics

NASA Astrophysics Data System (ADS)

Shut, V. N.; Gavrilov, A. V.

2008-11-01

Thermal stresses emerging in a barium titanate-based semiconducting ceramic during heating by electric current are studied using numerical methods. It is shown that the highest tensile stresses are formed in the plane equidistant from the electrodes. The values of these stresses can be as high as 70 MPa, which is commensurate with the critical stresses. A method is proposed for reducing stresses by developing thermistors with a layered structure.

Heavy metal-induced stress in rice crops detected using multi-temporal Sentinel-2 satellite images.

PubMed

Liu, Meiling; Wang, Tiejun; Skidmore, Andrew K; Liu, Xiangnan

2018-05-05

Regional-level information on heavy metal pollution in agro-ecosystems is essential for food security because excessive levels of heavy metals in crops may pose risks to humans. However, collecting this information over large areas is inherently costly. This paper investigates the possibility of applying multi-temporal Sentinel-2 satellite images to detect heavy metal-induced stress (i.e., Cd stress) in rice crops in four study areas in Zhuzhou City, Hunan Province, China. For this purpose, we compared seven Sentinel-2 images acquired in 2016 and 2017 with in situ measured hyper-spectral data, chlorophyll content, rice leaf area index, and heavy metal concentrations in soil collected from 2014 to 2017. Vegetation indices (VIs) related to red edge bands were referred to as the sensitive indicators for screening stressed rice from unstressed rice. The coefficients of spatio-temporal variation (CSTV) derived from the VIs allowed us to discriminate crops exposed to pollution from heavy metals as well as environmental stressors. The results indicate that (i) the red edge chlorophyll index, the red edge position index, and the normalized difference red edge 2 index derived from multi-temporal Sentinel-2 images were good indicators for screening stressed rice from unstressed rice; (ii) Rice under Cd stress remained stable with lower CSTV values of VIs overall growth stages in the experimental region, whereas rice under other stressors (i.e., pests and disease) showed abrupt changes at some growth stages and presented "hot spots" with greater CSTV values; and (iii) the proposed spatio-temporal anomaly detection method was successful at detecting rice under Cd stress; and CSTVs of rice VIs stabilized regardless of whether they were applied to consecutive growth stages or to two different crop years. This study suggests that regional heavy metal stress may be accurately detected using multi-temporal Sentinel-2 images, using VIs sensitive to the spatio

Maternal Active Mastication during Prenatal Stress Ameliorates Prenatal Stress-Induced Lower Bone Mass in Adult Mouse Offspring

PubMed Central

Azuma, Kagaku; Ogura, Minori; Kondo, Hiroko; Suzuki, Ayumi; Hayashi, Sakurako; Iinuma, Mitsuo; Onozuka, Minoru; Kubo, Kin-ya

2017-01-01

Chronic psychological stress is a risk factor for osteoporosis. Maternal active mastication during prenatal stress attenuates stress response. The aim of this study is to test the hypothesis that maternal active mastication influences the effect of prenatal stress on bone mass and bone microstructure in adult offspring. Pregnant ddY mice were randomly divided into control, stress, and stress/chewing groups. Mice in the stress and stress/chewing groups were placed in a ventilated restraint tube for 45 minutes, 3 times a day, and was initiated on day 12 of gestation and continued until delivery. Mice in the stress/chewing group were allowed to chew a wooden stick during the restraint stress period. The bone response of 5-month-old male offspring was evaluated using quantitative micro-CT, bone histomorphometry, and biochemical markers. Prenatal stress resulted in significant decrease of trabecular bone mass in both vertebra and distal femur of the offspring. Maternal active mastication during prenatal stress attenuated the reduced bone formation and increased bone resorption, improved the lower trabecular bone volume and bone microstructural deterioration induced by prenatal stress in the offspring. These findings indicate that maternal active mastication during prenatal stress can ameliorate prenatal stress-induced lower bone mass of the vertebra and femur in adult offspring. Active mastication during prenatal stress in dams could be an effective coping strategy to prevent lower bone mass in their offspring. PMID:28553167

Implant-Supported Fixed Partial Prostheses With Different Prosthetic Materials: A Three-Dimensional Finite Element Stress Analysis.

PubMed

Arinc, Hakan

2018-06-01

To evaluate the effects of prosthetic material on the degree of stress to the cortical bone, trabecular bone, framework, and implants using finite element analysis (FEA). A mandibular implant-supported fixed prosthesis was designed. Different prosthetic materials [cobalt-chromium-supported ceramic, zirconia-supported ceramic, and zirconia-reinforced polymethyl methacrylate (ZRPMMA)-supported resin] were used. FEA was used to evaluate stress under different loading conditions. Maximum principal (σmax), minimum principal (σmin), and von Mises (σvM) stress values were obtained. Similar σmax, σmin, and σvM values were observed in the cortical and trabecular bones and in implants under both loading conditions, with the exception of the ZRPMMA model, which showed the highest σmax, σmin, and σvM values in oblique loading. The ZRPMMA model had the lowest σvM value in the framework under both loading conditions. ZRPMMA had the lowest stress values in the framework, with increased stress values in the implants and bone tissue. Framework and veneering materials may influence stress values under different loading conditions.

Lamination residual stresses in hybrid composites, part 1

NASA Technical Reports Server (NTRS)

Daniel, I. M.; Liber, T.

1976-01-01

An experimental investigation was conducted to study lamination residual stresses for various material and loading parameters. The effects of hybridization on residual stresses and residual properties after thermal cycling under load were determined in angle-ply graphite/Kevlar/epoxy and graphite/S-glass/epoxy laminates. Residual strains in the graphite plies are not appreciably affected by the type and number of hybridizing plies. Computed residual stresses at room temperature in the S-glass plies reach values up to seventy-five percent of the transverse strength of the material. Computed residual stresses in the graphite plies exceed the static strength by approximately ten percent. In the case of Kevlar plies, computed residual stresses far exceed the static strength indicating possible early failure of these plies. Static testing of the hybrids above indicates that failure is governed by the ultimate strain of the graphite plies. In thermally cycled hybrids, in general, residual moduli were somewhat lower and residual strengths were higher than initial values.

Three dimensional stress vector sensor array and method therefor

DOEpatents

Pfeifer, Kent Bryant; Rudnick, Thomas Jeffery

2005-07-05

A sensor array is configured based upon capacitive sensor techniques to measure stresses at various positions in a sheet simultaneously and allow a stress map to be obtained in near real-time. The device consists of single capacitive elements applied in a one or two dimensional array to measure the distribution of stresses across a mat surface in real-time as a function of position for manufacturing and test applications. In-plane and normal stresses in rolling bodies such as tires may thus be monitored.

SKA2 Methylation is Involved in Cortisol Stress Reactivity and Predicts the Development of Post-Traumatic Stress Disorder (PTSD) After Military Deployment.

PubMed

Boks, Marco P; Rutten, Bart P F; Geuze, Elbert; Houtepen, Lotte C; Vermetten, Eric; Kaminsky, Zachary; Vinkers, Christiaan H

2016-04-01

Genomic variation in the SKA2 gene has recently been identified as a promising suicide biomarker. In light of its role in glucocorticoid receptor transactivation, we investigated whether SKA2 DNA methylation influences cortisol stress reactivity and is involved in the development of post-traumatic stress disorder (PTSD). Increased SKA2 methylation was significantly associated with lower cortisol stress reactivity in 85 healthy individuals exposed to the Trier Social Stress Test (B=-173.40, t=-2.324, p-value=0.023). Next, we observed that longitudinal decreases in SKA2 methylation after deployment were associated with the emergence of post-deployment PTSD symptoms in a Dutch military cohort (N=93; B=-0.054, t=-3.706, p-value=3.66 × 10(-4)). In contrast, exposure to traumatic stress during deployment by itself resulted in longitudinal increases in SKA2 methylation (B=0.037, t=4.173, p-value=6.98 × 10(-5)). Using pre-deployment SKA2 methylation levels and childhood trauma exposure, we found that the previously published suicide prediction rule significantly predicted post-deployment PTSD symptoms (AUC=0.66, 95% CI: 0.53-0.79) with an optimal sensitivity of 0.81 and specificity of 0.91. Permutation analysis using random methylation loci supported these findings. Together, these data establish the importance of SKA2 for cortisol stress responsivity and the development of PTSD and provide further evidence that SKA2 is a promising biomarker for stress-related disorders including PTSD.

The reliability of the Bad Sobernheim Stress Questionnaire (BSSQbrace) in adolescents with scoliosis during brace treatment

PubMed Central

Botens-Helmus, Christine; Klein, Rolf; Stephan, Carola

2006-01-01

Background A new instrument to assess stress scoliosis patients have whilst wearing their brace has been developed. Aim of this study was to test the reliability of this new instrument. Methods Eight questions are provided focussing on this topic only, including two questions to test the credibility. A max. score of 24 can be achieved (from 0 for most stress to 24 for least stress). We have proposed a subdivision of the score values as follows: 0–8 (strong stress), 9–16 (medium stress) and 17–24 (little stress). 85 patients were invited to take part in this study and to complete the BSSQbrace questionnaire twice, once at the first presentation and a second after a further three days. 62 patients with an average age of 14,5 years and an average Cobb angle of 40° returned their fully completed questionnaires. Results The average stress value was 12,5/24 at the first measurement and 12,4/24 at the second measurement. Ceiling value was 23; floor value 2. The average stress value was 12,5 / 24 at the first measurement and 12,4 / 24 at the second measurement (from 0 for most stress to 24 for least stress). Ceiling value was 23; floor value 2. There was a correlation of 0,88 (Intraclass Correlation Coefficient) between the values of the two measurements. Cronbach alpha was 0, 97. Conclusion The BSSQbrace questionnaire is reliable with good internal consistency and reproducibility. It can be used to measure the coping strategies a patient uses and the impairment a patient feels to have, whilst wearing a brace. PMID:17176483

Diagnostic value of ST-segment deviations during cardiac exercise stress testing: Systematic comparison of different ECG leads and time-points.

PubMed

Puelacher, Christian; Wagener, Max; Abächerli, Roger; Honegger, Ursina; Lhasam, Nundsin; Schaerli, Nicolas; Prêtre, Gil; Strebel, Ivo; Twerenbold, Raphael; Boeddinghaus, Jasper; Nestelberger, Thomas; Rubini Giménez, Maria; Hillinger, Petra; Wildi, Karin; Sabti, Zaid; Badertscher, Patrick; Cupa, Janosch; Kozhuharov, Nikola; du Fay de Lavallaz, Jeanne; Freese, Michael; Roux, Isabelle; Lohrmann, Jens; Leber, Remo; Osswald, Stefan; Wild, Damian; Zellweger, Michael J; Mueller, Christian; Reichlin, Tobias

2017-07-01

Exercise ECG stress testing is the most widely available method for evaluation of patients with suspected myocardial ischemia. Its major limitation is the relatively poor accuracy of ST-segment changes regarding ischemia detection. Little is known about the optimal method to assess ST-deviations. A total of 1558 consecutive patients undergoing bicycle exercise stress myocardial perfusion imaging (MPI) were enrolled. Presence of inducible myocardial ischemia was adjudicated using MPI results. The diagnostic value of ST-deviations for detection of exercise-induced myocardial ischemia was systematically analyzed 1) for each individual lead, 2) at three different intervals after the J-point (J+40ms, J+60ms, J+80ms), and 3) at different time points during the test (baseline, maximal workload, 2min into recovery). Exercise-induced ischemia was detected in 481 (31%) patients. The diagnostic accuracy of ST-deviations was highest at +80ms after the J-point, and at 2min into recovery. At this point, ST-amplitude showed an AUC of 0.63 (95% CI 0.59-0.66) for the best-performing lead I. The combination of ST-amplitude and ST-slope in lead I did not increase the AUC. Lead I reached a sensitivity of 37% and a specificity of 83%, with similar sensitivity to manual ECG analysis (34%, p=0.31) but lower specificity (90%, p<0.001). When using ECG stress testing for evaluation of patients with suspected myocardial ischemia, the diagnostic accuracy of ST-deviations is highest when evaluated at +80ms after the J-point, and at 2min into recovery. Copyright © 2017 Elsevier B.V. All rights reserved.

Shear induced migration of particles in a yield stress fluid: experiment

NASA Astrophysics Data System (ADS)

Hormozi, Sarah; Gholami, Mohammad; Rashedi, Ahmadreza; Lenoir, Nicolas; Ovarlez, Guillaume

2017-11-01

We have performed rheometry coupled with X-ray radiography in a narrow gap Couette cell filled with a suspension of spherical particles in a yield stress fluid. In this setup, the shear rate is discontinuous changing from a constant value in the gap to zero in the reservoir located at the top. This shear rate inhomogeneity results in the migration of particles from the gap to the reservoir, so-called Shear Induced Migration (SIM). The rheometry results give us insight into understanding the bulk rheology in the presence of shear rate and solid volume fraction inhomogeneities. In addition to that, our recent X-ray radiography technique (Gholami et al., JOR. 2017) provides detailed information about the evolution of the solid volume fraction in the domain. These measurements allow us to refine the recent continuum model frameworks (Hormozi & Frigaard, JFM 2017) for SIM of particles in a yield stress suspending fluid. We show that complex rheology of the yield stress suspending fluid and formation of the islands of unyielded regions in the reservoir strongly affects the SIM of particles. This feature is absent when we deal with a Newtonian suspending fluid. NSF (Grant No. CBET-1554044- CAREER), ACS PRF (Grant No. 55661-DNI9).

Hsp70 as an indicator of stress in the cells after contact with nanoparticles

NASA Astrophysics Data System (ADS)

Hardilová, Šárka; Havrdová, Markéta; Panáček, Aleš; Kvítek, Libor; Zbořil, Radek

2015-05-01

In recent years, production of nanoparticles is increased and thus grows our contact with them too. Question of safety is closely related to the issue of use nanoparticles. There are a number of tests that monitor the viability, ROS production, the effect on the DNA and cell cycle, however, rarely encountered studies on stress in the cells after contact with nanoparticles. Heat shock proteins (HSP) are among the substances that can be used for monitoring stress in cells. HSP are structures with a chaperone activity. They are evolutionarily very old, conservative and they are found with a high degree of homology in prokaryotes and eukaryotes including humans. They exist at low concentrations under physiological conditions, while in the denaturing conditions e.g. high or low temperature, radiation, exposure to chemicals, heavy metals, or nanoparticles their expression is changed. HSPs are involved in maintaining homeostasis in the cell that the denatured protein conformations allow recovery to the original stage. One of the most common proteins from HSP family is Hsp70 - protein with a molecular weight of 70 kDa. The level of Hsp70 in a cell after exposure to the stress changes depending on the stress level to which the cell is exposed to and a time period during which lasted stressful conditions. Our research monitors stress levels of cells manifesting by Hsp70 production after contact with silver nanoparticles. Nanoparticles show different toxicity towards different types of target cells, which is reflected in the values of IC50 - concentration that kills 50% tested cells. Concentration of test substance toxic to one cell type may be innocuous to cells of another type. IC50 obtained from the MTT assay provides a suitable default data and if multiples of IC50 values are used, we can compare and generalize. Studies can be used to compare stress levels in cells that show different sensitivity to the tested nanoparticles compared with cells under optimal growth

Stress and Sleep Disorder

PubMed Central

Han, Kuem Sun; Kim, Lin

2012-01-01

The purpose of this study was to review potential, physiological, hormonal and neuronal mechanisms that may mediate the sleep changes. This paper investigates the literatures regarding the activity of the hypothalamic-pituitary-adrenal (HPA) axis, one of the main neuroendocrine stress systems during sleep in order to identify relations between stress and sleep disorder and the treatment of stress-induced insomnia. Sleep and wakefulness are regulated by the aminergic, cholinergic brainstem and hypothalamic systems. Activation of the HPA and/or the sympathetic nervous systems results in wakefulness and these hormones including corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), cortisol or corticosterone, noradrenaline, and adrenaline, are associated with attention and arousal. Stress-related insomnia leads to a vicious circle by activating the HPA system. An awareness of the close interaction between sleep and stress systems is emerging and the hypothalamus is now recognized as a key center for sleep regulation, with hypothalamic neurontransmitter systems providing the framework for therapeutic advances. An updated understanding of these systems may allow researchers to elucidate neural mechanisms of sleep disorder and to develop effective intervention for sleep disorder. PMID:23319874

A systematic investigation into b values prior to coming large earthquakes

NASA Astrophysics Data System (ADS)

Nanjo, K.; Yoshida, A.

2017-12-01

The Gutenberg-Richter law for frequency-magnitude distribution of earthquakes is now well established in seismology. The b value, the slope of the distribution, is supposed to reflect heterogeneity of seismogenic region (e.g. Mogi 1962) and development of interplate coupling in subduction zone (e.g. Nanjo et al., 2012; Tormann et al. 2015). In the laboratory as well as in the Earth's crust, the b value is known to be inversely dependent on differential stresses (Scholz 1968, 2015). In this context, the b value could serve as a stress meter to help locate asperities, the highly-stressed patches, in fault planes where large rupture energy is released (e.g. Schorlemmer & Wiemer 2005). However, it still remains uncertain whether the b values of events prior to coming large earthquakes are always low significantly. To clarify this issue, we conducted a systematic investigation into b values prior to large earthquakes in the Japanese Mainland. Since no physical definition of mainshock, foreshock, and aftershock is known, we simply investigated b values of the events with magnitudes larger than the lower-cutoff magnitude, Mc, prior to earthquakes equal to or larger than a threshold magnitude, Mth, where Mth>Mc. Schorlemmer et al. (2005) showed that the b value for different fault types differs significantly, which is supposed to reflect the feature that the fracture stress depends on fault types. Therefore, we classified fault motions into normal, strike-slip, and thrust types based on the mechanism solution of earthquakes, and computed b values of events associated with each fault motion separately. We found that the target events (M≥Mth) and the events that occurred prior to the target events both show a common systematic change in b: normal faulting events have the highest b values, thrust events the lowest and strike-slip events intermediate values. Moreover, we found that the b values for the prior events (M≥Mc) are significantly lower than the b values for the

Bacterial Dispersal Promotes Biodegradation in Heterogeneous Systems Exposed to Osmotic Stress

PubMed Central

Worrich, Anja; König, Sara; Banitz, Thomas; Centler, Florian; Frank, Karin; Thullner, Martin; Harms, Hauke; Miltner, Anja; Wick, Lukas Y.; Kästner, Matthias

2016-01-01

Contaminant biodegradation in soils is hampered by the heterogeneous distribution of degrading communities colonizing isolated microenvironments as a result of the soil architecture. Over the last years, soil salinization was recognized as an additional problem especially in arid and semiarid ecosystems as it drastically reduces the activity and motility of bacteria. Here, we studied the importance of different spatial processes for benzoate biodegradation at an environmentally relevant range of osmotic potentials (ΔΨo) using model ecosystems exhibiting a heterogeneous distribution of the soil-borne bacterium Pseudomonas putida KT2440. Three systematically manipulated scenarios allowed us to cover the effects of (i) substrate diffusion, (ii) substrate diffusion and autonomous bacterial dispersal, and (iii) substrate diffusion and autonomous as well as mediated bacterial dispersal along glass fiber networks mimicking fungal hyphae. To quantify the relative importance of the different spatial processes, we compared these heterogeneous scenarios to a reference value obtained for each ΔΨo by means of a quasi-optimal scenario in which degraders were ab initio homogeneously distributed. Substrate diffusion as the sole spatial process was insufficient to counteract the disadvantage due to spatial degrader heterogeneity at ΔΨo ranging from 0 to −1 MPa. In this scenario, only 13.8−21.3% of the quasi-optimal biodegradation performance could be achieved. In the same range of ΔΨo values, substrate diffusion in combination with bacterial dispersal allowed between 68.6 and 36.2% of the performance showing a clear downwards trend with decreasing ΔΨo. At −1.5 MPa, however, this scenario performed worse than the diffusion scenario, possibly as a result of energetic disadvantages associated with flagellum synthesis and emerging requirements to exceed a critical population density to resist osmotic stress. Network-mediated bacterial dispersal kept biodegradation

Analysis of electric vehicle's trip cost allowing late arrival

NASA Astrophysics Data System (ADS)

Leng, Jun-Qiang; Liu, Wei-Yi; Zhao, Lin

2017-05-01

In this paper, we use a car-following model to study each electric vehicle's trip cost and the total trip cost allowing late arrival. The numerical result show that the electricity cost has great effects on each commuter's trip cost and the total trip costs and that these effects are dependent on each commuter's time headway at the origin, but the electricity cost has no prominent impacts on the minimum value of total trip cost under each commuter's different time headway at the origin.

Stress wave propagation on standing trees. Part 2, Formation of 3D stress wave contour maps.

Treesearch

Juan Su; Houjiang Zhang; Xiping Wang

2009-01-01

Nondestructive evaluation (NDE) of wood quality in standing trees is an important procedure in the forest operational value chain worldwide. The goal of this paper is to investigate how a stress wave travel in a tree stem as it is introduced into the tree through a mechanical impact. Experimental stress wave data was obtained on freshly cut red pine logs in the...

Hyperspectral image analysis for water stress detection of apple trees

USDA-ARS?s Scientific Manuscript database

Plant stress significantly reduces plant productivity. Automated on-the-go mapping of plant stress would allow for a timely intervention and mitigation of the problem before critical thresholds are exceeded, thereby maximizing productivity. The spectral signature of plant leaves was analyzed by a ...

Perceived Relationship Quality and Family Values: Online Graduate Students and Intimate Partners

ERIC Educational Resources Information Center

Jones-Garcia Stage, Tracy

2017-01-01

Previous research found that relationship quality (RQ) for intimate couples may be adversely effected in times of stress, potentially decreasing marital satisfaction up to 36% during a four-year period for high stress couples. Previous research indicated family values (FV) may mediate RQ in stressful times; however, no research has examined this…

41 CFR 302-17.8 - Rules and procedures for determining the RIT allowance in Year 2.

Code of Federal Regulations, 2012 CFR

2012-07-01

... CMTR's cannot be calculated by merely adding the Federal, State, and local marginal tax rates together... income taxes but none for local income tax, the value of “L” is zero and the CMTR formula may be solved... Federal Travel Regulation System RELOCATION ALLOWANCES MISCELLANEOUS ALLOWANCES 17-RELOCATION INCOME TAX...

41 CFR 302-17.8 - Rules and procedures for determining the RIT allowance in Year 2.

Code of Federal Regulations, 2011 CFR

2011-07-01

... CMTR's cannot be calculated by merely adding the Federal, State, and local marginal tax rates together... income taxes but none for local income tax, the value of “L” is zero and the CMTR formula may be solved... Federal Travel Regulation System RELOCATION ALLOWANCES MISCELLANEOUS ALLOWANCES 17-RELOCATION INCOME TAX...

41 CFR 302-17.8 - Rules and procedures for determining the RIT allowance in Year 2.

Code of Federal Regulations, 2013 CFR

2013-07-01

... CMTR's cannot be calculated by merely adding the Federal, State, and local marginal tax rates together... income taxes but none for local income tax, the value of “L” is zero and the CMTR formula may be solved... Federal Travel Regulation System RELOCATION ALLOWANCES MISCELLANEOUS ALLOWANCES 17-RELOCATION INCOME TAX...

41 CFR 302-17.8 - Rules and procedures for determining the RIT allowance in Year 2.

Code of Federal Regulations, 2014 CFR

2014-07-01

... CMTR's cannot be calculated by merely adding the Federal, State, and local marginal tax rates together... income taxes but none for local income tax, the value of “L” is zero and the CMTR formula may be solved... Federal Travel Regulation System RELOCATION ALLOWANCES MISCELLANEOUS ALLOWANCES 17-RELOCATION INCOME TAX...

Alternative Splicing Control of Abiotic Stress Responses.

PubMed

Laloum, Tom; Martín, Guiomar; Duque, Paula

2018-02-01

Alternative splicing, which generates multiple transcripts from the same gene, is an important modulator of gene expression that can increase proteome diversity and regulate mRNA levels. In plants, this post-transcriptional mechanism is markedly induced in response to environmental stress, and recent studies have identified alternative splicing events that allow rapid adjustment of the abundance and function of key stress-response components. In agreement, plant mutants defective in splicing factors are severely impaired in their response to abiotic stress. Notably, mounting evidence indicates that alternative splicing regulates stress responses largely by targeting the abscisic acid (ABA) pathway. We review here current understanding of post-transcriptional control of plant stress tolerance via alternative splicing and discuss research challenges for the near future. Copyright © 2017 Elsevier Ltd. All rights reserved.

Transgenerational transmission of a stress-coping phenotype programmed by early-life stress in the Japanese quail

PubMed Central

Zimmer, Cédric; Larriva, Maria; Boogert, Neeltje J.; Spencer, Karen A.

2017-01-01

An interesting aspect of developmental programming is the existence of transgenerational effects that influence offspring characteristics and performance later in life. These transgenerational effects have been hypothesized to allow individuals to cope better with predictable environmental fluctuations and thus facilitate adaptation to changing environments. Here, we test for the first time how early-life stress drives developmental programming and transgenerational effects of maternal exposure to early-life stress on several phenotypic traits in their offspring in a functionally relevant context using a fully factorial design. We manipulated pre- and/or post-natal stress in both Japanese quail mothers and offspring and examined the consequences for several stress-related traits in the offspring generation. We show that pre-natal stress experienced by the mother did not simply affect offspring phenotype but resulted in the inheritance of the same stress-coping traits in the offspring across all phenotypic levels that we investigated, shaping neuroendocrine, physiological and behavioural traits. This may serve mothers to better prepare their offspring to cope with later environments where the same stressors are experienced. PMID:28387355

A geometric exploration of stress in deformed liquid foams

NASA Astrophysics Data System (ADS)

Evans, Myfanwy E.; Schröder-Turk, Gerd E.; Kraynik, Andrew M.

2017-03-01

We explore an alternate way of looking at the rheological response of a yield stress fluid: using discrete geometry to probe the heterogeneous distribution of stress in soap froth. We present quasi-static, uniaxial, isochoric compression and extension of three-dimensional random monodisperse soap froth in periodic boundary conditions and examine the stress and geometry that result. The stress and shape anisotropy of individual cells is quantified by Q, a scalar measure derived from the interface tensor that gauges each cell’s contribution to the global stress. Cumulatively, the spatial distribution of highly deformed cells allows us to examine how stress is internally distributed. The topology of highly deformed cells, how they arrange relative to one another in space, gives insight into the heterogeneous distribution of stress.

Assessing Lifetime Stress Exposure Using the Stress and Adversity Inventory for Adults (Adult STRAIN): An Overview and Initial Validation.

PubMed

Slavich, George M; Shields, Grant S

2018-01-01

Numerous theories have proposed that acute and chronic stressors may exert a cumulative effect on life-span health by causing biological "wear and tear," or allostatic load, which in turn promotes disease. Very few studies have directly tested such models, though, partly because of the challenges associated with efficiently assessing stress exposure over the entire life course. To address this issue, we developed the first online system for systematically assessing lifetime stress exposure, called the Stress and Adversity Inventory (STRAIN), and describe its initial validation here. Adults recruited from the community (n = 205) were administered the STRAIN, Childhood Trauma Questionnaire-Short Form, and Perceived Stress Scale, as well as measures of socioeconomic status, personality, social desirability, negative affect, mental and physical health complaints, sleep quality, computer-assessed executive function, and doctor-diagnosed general health problems and autoimmune disorders. The STRAIN achieved high acceptability and was completed relatively quickly (mean = 18 minutes 39 seconds; interquartile range = 12-23 minutes). The structure of the lifetime stress data best fit two latent classes overall and five distinct trajectories over time. Concurrent associations with the Childhood Trauma Questionnaire-Short Form and Perceived Stress Scale were good (r values = .147-.552). Moreover, the STRAIN was not significantly related to personality traits or social desirability characteristics and, in adjusted analyses, emerged as the measure most strongly associated with all six of the health and cognitive outcomes assessed except current mental health complaints (β values = .16-.41; risk ratios = 1.02-1.04). Finally, test-retest reliability for the main stress exposure indices over 2-4 weeks was excellent (r values = .904-.919). The STRAIN demonstrated good usability and acceptability; very good concurrent, discriminant, and predictive validity; and excellent test

Assessing Lifetime Stress Exposure Using the Stress and Adversity Inventory for Adults (Adult STRAIN): An Overview and Initial Validation

PubMed Central

Slavich, George M.; Shields, Grant S.

2018-01-01

ABSTRACT Objective Numerous theories have proposed that acute and chronic stressors may exert a cumulative effect on life-span health by causing biological “wear and tear,” or allostatic load, which in turn promotes disease. Very few studies have directly tested such models, though, partly because of the challenges associated with efficiently assessing stress exposure over the entire life course. To address this issue, we developed the first online system for systematically assessing lifetime stress exposure, called the Stress and Adversity Inventory (STRAIN), and describe its initial validation here. Methods Adults recruited from the community (n = 205) were administered the STRAIN, Childhood Trauma Questionnaire—Short Form, and Perceived Stress Scale, as well as measures of socioeconomic status, personality, social desirability, negative affect, mental and physical health complaints, sleep quality, computer-assessed executive function, and doctor-diagnosed general health problems and autoimmune disorders. Results The STRAIN achieved high acceptability and was completed relatively quickly (mean = 18 minutes 39 seconds; interquartile range = 12–23 minutes). The structure of the lifetime stress data best fit two latent classes overall and five distinct trajectories over time. Concurrent associations with the Childhood Trauma Questionnaire—Short Form and Perceived Stress Scale were good (r values = .147–.552). Moreover, the STRAIN was not significantly related to personality traits or social desirability characteristics and, in adjusted analyses, emerged as the measure most strongly associated with all six of the health and cognitive outcomes assessed except current mental health complaints (β values = .16–.41; risk ratios = 1.02–1.04). Finally, test-retest reliability for the main stress exposure indices over 2–4 weeks was excellent (r values = .904–.919). Conclusions The STRAIN demonstrated good usability and acceptability; very good concurrent

Dynamical states, possibilities and propagation of stress signal

PubMed Central

Malik, Md. Zubbair; Ali, Shahnawaz; Singh, Soibam Shyamchand; Ishrat, Romana; Singh, R. K. Brojen

2017-01-01

The stress driven dynamics of Notch-Wnt-p53 cross-talk is subjected to a few possible dynamical states governed by simple fractal rules, and allowed to decide its own fate by choosing one of these states which are contributed from long range correlation with varied fluctuations due to active molecular interaction. The topological properties of the networks corresponding to these dynamical states have hierarchical features with assortive structure. The stress signal driven by nutlin and modulated by mediator GSK3 acts as anti-apoptotic signal in this system, whereas, the stress signal driven by Axin and modulated by GSK3 behaves as anti-apoptotic for a certain range of Axin and GSK3 interaction, and beyond which the signal acts as favor-apoptotic signal. However, this stress system prefers to stay in an active dynamical state whose counterpart complex network is closest to hierarchical topology with exhibited roles of few interacting hubs. During the propagation of stress signal, the system allows the propagator pathway to inherit all possible properties of the state to the receiver pathway/pathways with slight modifications, indicating efficient information processing and democratic sharing of responsibilities in the system via cross-talk. The increase in the number of cross-talk pathways in the system favors to establish self-organization. PMID:28106087

Dynamical states, possibilities and propagation of stress signal.

PubMed

Malik, Md Zubbair; Ali, Shahnawaz; Singh, Soibam Shyamchand; Ishrat, Romana; Singh, R K Brojen

2017-01-20

The stress driven dynamics of Notch-Wnt-p53 cross-talk is subjected to a few possible dynamical states governed by simple fractal rules, and allowed to decide its own fate by choosing one of these states which are contributed from long range correlation with varied fluctuations due to active molecular interaction. The topological properties of the networks corresponding to these dynamical states have hierarchical features with assortive structure. The stress signal driven by nutlin and modulated by mediator GSK3 acts as anti-apoptotic signal in this system, whereas, the stress signal driven by Axin and modulated by GSK3 behaves as anti-apoptotic for a certain range of Axin and GSK3 interaction, and beyond which the signal acts as favor-apoptotic signal. However, this stress system prefers to stay in an active dynamical state whose counterpart complex network is closest to hierarchical topology with exhibited roles of few interacting hubs. During the propagation of stress signal, the system allows the propagator pathway to inherit all possible properties of the state to the receiver pathway/pathways with slight modifications, indicating efficient information processing and democratic sharing of responsibilities in the system via cross-talk. The increase in the number of cross-talk pathways in the system favors to establish self-organization.

Stress, eating and the reward system.

PubMed

Adam, Tanja C; Epel, Elissa S

2007-07-24

An increasing number of people report concerns about the amount of stress in their life. At the same time obesity is an escalating health problem worldwide. Evidence is accumulating rapidly that stress related chronic stimulation of the hypothalamic-pituitary-adrenal (HPA) axis and resulting excess glucocorticoid exposure may play a potential role in the development of visceral obesity. Since adequate regulation of energy and food intake under stress is important for survival, it is not surprising that the HPA axis is not only the 'conductor' of an appropriate stress response, but is also tightly intertwined with the endocrine regulation of appetite. Here we attempt to link animal and human literatures to tease apart how different types of psychological stress affect eating. We propose a theoretical model of Reward Based Stress Eating. This model emphasizes the role of cortisol and reward circuitry on motivating calorically dense food intake, and elucidating potential neuroendocrine mediators in the relationship between stress and eating. The addiction literature suggests that the brain reward circuitry may be a key player in stress-induced food intake. Stress as well as palatable food can stimulate endogenous opioid release. In turn, opioid release appears to be part of an organisms' powerful defense mechanism protecting from the detrimental effects of stress by decreasing activity of the HPA axis and thus attenuating the stress response. Repeated stimulation of the reward pathways through either stress induced HPA stimulation, intake of highly palatable food or both, may lead to neurobiological adaptations that promote the compulsive nature of overeating. Cortisol may influence the reward value of food via neuroendocrine/peptide mediators such as leptin, insulin and neuropeptide Y (NPY). Whereas glucocorticoids are antagonized by insulin and leptin acutely, under chronic stress, that finely balanced system is dysregulated, possibly contributing to increased food

Completed Beltrami-Michell formulation for analyzing mixed boundary value problems in elasticity

NASA Technical Reports Server (NTRS)

Patnaik, Surya N.; Kaljevic, Igor; Hopkins, Dale A.; Saigal, Sunil

1995-01-01

In elasticity, the method of forces, wherein stress parameters are considered as the primary unknowns, is known as the Beltrami-Michell formulation (BMF). The existing BMF can only solve stress boundary value problems; it cannot handle the more prevalent displacement of mixed boundary value problems of elasticity. Therefore, this formulation, which has restricted application, could not become a true alternative to the Navier's displacement method, which can solve all three types of boundary value problems. The restrictions in the BMF have been alleviated by augmenting the classical formulation with a novel set of conditions identified as the boundary compatibility conditions. This new method, which completes the classical force formulation, has been termed the completed Beltrami-Michell formulation (CBMF). The CBMF can solve general elasticity problems with stress, displacement, and mixed boundary conditions in terms of stresses as the primary unknowns. The CBMF is derived from the stationary condition of the variational functional of the integrated force method. In the CBMF, stresses for kinematically stable structures can be obtained without any reference to the displacements either in the field or on the boundary. This paper presents the CBMF and its derivation from the variational functional of the integrated force method. Several examples are presented to demonstrate the applicability of the completed formulation for analyzing mixed boundary value problems under thermomechanical loads. Selected example problems include a cylindrical shell wherein membrane and bending responses are coupled, and a composite circular plate.

Driving- stress waveform and the determination of rock internal friction by the stress-strain curve method.

USGS Publications Warehouse

Hsi-Ping, Liu

1980-01-01

Harmonic distortion in the stress-time function applied to rock specimens affects the measurement of rock internal friction in the seismic wave periods by the stress-strain hysteresis loop method. If neglected, the harmonic distortion can cause measurements of rock internal friction to be in error by 3O% in the linear range. The stress-time function therefore must be recorded and Fourier analysed for correct interpretation of the experimental data. Such a procedure would also yield a value for internal friction at the higher harmonic frequencies.-Author

Stress Map 2.0: Updating the Stress Map of the Western Canadian Sedimentary Basin

NASA Astrophysics Data System (ADS)

Mallyon, D.; Schmitt, D. R.; Currie, C. A.; Gu, Y. J.; Heidbach, O.

2015-12-01

The greatest horizontal compression in much of the Western Canada Sedimentary Basin appears to uniformly trend NE-SW. Beyond this, major gaps remain in our knowledge of stress magnitudes and even faulting regimes. This lack of quantitative information impedes a proper understanding of seismic events that appear to be linked to hydraulic fracturing stimulations. Apart from this immediate concern, such seismicity could impact long term green-house gas sequestration and geothermal energy development. As part of the Helmholtz-Alberta geothermal collaboration, we are developing a program to update this crustal stress state information. The program consists of more immediate studies related to conventional analysis of borehole image logs, core fractures, and transient pressure records as can be made available. Data sets analyzed to date include logs to 3.5 km depth from areas experiencing induced seismicity, from 2.5 km depth within the Precambrian craton in NE Alberta, and to 400 m depth within a large carbonate platform. All these data largely confirm the NE-SW stress directions. In some cases, the configurations of drilling induced tensile fractures and borehole breakouts allow the faulting regime to be constrained. The addition of new seismometers to the region is also allowing for the refinement of earthquake focal mechanisms. Finally, a dramatic contrast in lithosphere thickness, composition and geothermal gradient exists at the contact between the Cordillera and the North American craton; therefore, lithosphere-scale numerical models are also being developed to quantify the relative contribution of geodynamic processes, such as mantle flow and contact geometry, to the observed stress regime within the basin.

[Personality and occupation stress of workers in processing line in Guangzhou].

PubMed

Lin, Qiu-hong; Zhang, Wei-sen; Zhou, Jing-dong; Fan, Yuan-yu; Liu, Li-fen; Li, Jian-lin; Liu, Wei-wei

2009-12-01

To study relationships between personality and occupational stress of workers in processing line in Guangzhou. 452 workers in processing line in Guangzhou were investigated by the Eysenck Personality Questionnaire (EPQ) and Occupational Stress Indicator (OSI). N scores and P scores of EPQ were positively correlated with the occupational stress and the poor physical fitness status (r value was 0.196, 0.128, 0.202, 0.218, respectively) (P < 0.01). N scores of EPQ were positively correlated with the type A behavior (r = 0.164) and negatively correlated with the mental well-being level (r = -0.196, P < 0.01). P scores of EPQ were negative correlated with the sense of job satisfaction and the stress coping ability(r value was -0.146, -0.140, respectively) (P < 0.01). E scores and L scores of EPQ were negatively correlated with the type A behavior (r value was -0.159, -0.138, respectively) (P < 0.01). E scores of EPQ were positively correlated with the stress coping ability (r = 0.176, P < 0.01). L scores of EPQ were negatively correlated with the occupational stress, the poor physical fitness status and the explanation to vicinity event (r value was -0.139, -0.140, -0.111, respectively) (P < 0.01, P < 0.05). The personality of neuroticism, psychoticism and introversion may be related to the occupational stress, the sense of job satisfaction and unhealthy mental reaction.

Defining in-situ stress magnitude and the responses of geology to stress anisotropy in heterogeneous lithologies for the United Kingdom

NASA Astrophysics Data System (ADS)

Kingdon, A.; Fellgett, M. W.; Williams, J. D. O.

2017-12-01

Exploitation of shale gas in the USA has led to interest in similar UK deposits. After tremors at the Preese Hall well in 2011, the process of hydraulic fracturing has become contentious. In-situ stress orientation controls the direction that fractures propagate from a well. World Stress Map (WSM) data coverage for the UK has historically been sparse. Improvements to the stress orientations for the UK are vital for reducing risk levels of induced seismicity. In some offshore basins, maximum horizontal stress (SHMax) is sub-parallel to major inverted Permo-Triassic faults, episodically reactivated during the Cenozoic, indicating a degree of structural control. Understanding for UK stress magnitude has been poor. Data for Northern England has been augmented with new estimates of vertical stress (Sv), minimum horizontal stress (Shmin) and pore pressure, focussed on potentially prospective basins east and west of the Pennines. Calculated values combined with legacy hydraulic fracturing and overcoring data show vertical stress gradients vary from 23 to 26 MPa/Km-1. Cheshire and Scotland show higher Shmin values by 2 MPa/Km-1 compared to Yorkshire and South East England. SHMax values exceeds the Sv which in turn exceeds Shmin indicating a predominantly strike slip environment. Pore pressure appears to be uniformly hydrostatic across the studied regions. There is some evidence above 1200 m depth of reverse faulting in igneous rocks in Cornwall, Leicestershire and Cumbria. Analysis of borehole imaging for the lithologically heterogeneous Carboniferous Coal Measures, highlights variability failure modes over confined vertical intervals. Breakouts are disproportionately located in "seatearths", palaeosols located stratigraphically beneath coal seams. Drilling induced tensile fractures are located within close proximity in overbank silt/clay facies and relatively massive channel sands that typically over and underlie coal deposits. Strength tests show that breakouts occur in

Ways to Manage Stress and Avoid Teacher Burnout.

ERIC Educational Resources Information Center

Hylton, John

1989-01-01

Suggests strategies for dealing with job stress and for prolonging career satisfaction. Stresses time management as a prime coping tool. Encourages reviewing objectives, and planning and setting priorities. Points out value of good physical health to development of mental fitness. (LS)

Probability of stress-corrosion fracture under random loading

NASA Technical Reports Server (NTRS)

Yang, J. N.

1974-01-01

Mathematical formulation is based on cumulative-damage hypothesis and experimentally-determined stress-corrosion characteristics. Under both stationary random loadings, mean value and variance of cumulative damage are obtained. Probability of stress-corrosion fracture is then evaluated, using principle of maximum entropy.

Oxidative stress, redox stress or redox success?

PubMed

Gutteridge, John M C; Halliwell, Barry

2018-05-09

The first life forms evolved in a highly reducing environment. This reduced state is still carried by cells today, which makes the concept of "reductive stress" somewhat redundant. When oxygen became abundant on the Earth, due to the evolution of photosynthesis, life forms had to adapt or become extinct. Living organisms did adapt, proliferated and an explosion of new life forms resulted, using reactive oxygen species (ROS) to drive their evolution. Adaptation to oxygen and its reduction intermediates necessitated the simultaneous evolution of select antioxidant defences, carefully regulated to allow ROS to perform their major roles. Clearly this "oxidative stress" did not cause a major problem to the evolution of complex life forms. Why not? Iron and oxygen share a close relationship in aerobic evolution. Iron is used in proteins to transport oxygen, promote electron transfers, and catalyse chemical reactions. In all of these functions, iron is carefully sequestered within proteins and restricted from reacting with ROS, this sequestration being one of our major antioxidant defences. Iron was abundant to life forms before the appearance of oxygen. However, oxygen caused its oxidative precipitation from solution and thereby decreased its bioavailability and thus the risk of iron-dependent oxidative damage. Micro-organisms had to adapt and develop strategies involving siderophores to acquire iron from the environment and eventually their host. This battle for iron between bacteria and animal hosts continues today, and is a much greater daily threat to our survival than "oxidative stress" and "redox stress". Copyright © 2018. Published by Elsevier Inc.

Comparison of measured temperatures, thermal stresses and creep residues with predictions on a built-up titanium structure

NASA Technical Reports Server (NTRS)

Jenkins, Jerald M.

1987-01-01

Temperature, thermal stresses, and residual creep stresses were studied by comparing laboratory values measured on a built-up titanium structure with values calculated from finite-element models. Several such models were used to examine the relationship between computational thermal stresses and thermal stresses measured on a built-up structure. Element suitability, element density, and computational temperature discrepancies were studied to determine their impact on measured and calculated thermal stress. The optimum number of elements is established from a balance between element density and suitable safety margins, such that the answer is acceptably safe yet is economical from a computational viewpoint. It is noted that situations exist where relatively small excursions of calculated temperatures from measured values result in far more than proportional increases in thermal stress values. Measured residual stresses due to creep significantly exceeded the values computed by the piecewise linear elastic strain analogy approach. The most important element in the computation is the correct definition of the creep law. Computational methodology advances in predicting residual stresses due to creep require significantly more viscoelastic material characterization.

Memory dynamics under stress.

PubMed

Quaedflieg, Conny W E M; Schwabe, Lars

2018-03-01

Stressful events have a major impact on memory. They modulate memory formation in a time-dependent manner, closely linked to the temporal profile of action of major stress mediators, in particular catecholamines and glucocorticoids. Shortly after stressor onset, rapidly acting catecholamines and fast, non-genomic glucocorticoid actions direct cognitive resources to the processing and consolidation of the ongoing threat. In parallel, control of memory is biased towards rather rigid systems, promoting habitual forms of memory allowing efficient processing under stress, at the expense of "cognitive" systems supporting memory flexibility and specificity. In this review, we discuss the implications of this shift in the balance of multiple memory systems for the dynamics of the memory trace. Specifically, stress appears to hinder the incorporation of contextual details into the memory trace, to impede the integration of new information into existing knowledge structures, to impair the flexible generalisation across past experiences, and to hamper the modification of memories in light of new information. Delayed, genomic glucocorticoid actions might reverse the control of memory, thus restoring homeostasis and "cognitive" control of memory again.

Dislocation-induced stress in polycrystalline materials: mesoscopic simulations in the dislocation density formalism

NASA Astrophysics Data System (ADS)

Berkov, D. V.; Gorn, N. L.

2018-06-01

In this paper we present a simple and effective numerical method which allows a fast Fourier transformation-based evaluation of stress generated by dislocations with arbitrary directions and Burgers vectors if the (site-dependent) dislocation density is known. Our method allows the evaluation of the dislocation stress using a rectangular grid with shape-anisotropic discretization cells without employing higher multipole moments of the dislocation interaction coefficients. Using the proposed method, we first simulate the stress created by relatively simple non-homogeneous distributions of vertical edge and so-called ‘mixed’ dislocations in a disk-shaped sample, which is necessary to understand the dislocation behavior in more complicated systems. The main part of our research is devoted to the stress distribution in polycrystalline layers with the dislocation density rapidly varying with the distance to the layer bottom. Considering GaN as a typical example of such systems, we investigate dislocation-induced stress for edge and mixed dislocations, having random orientations of Burgers vectors among crystal grains. We show that the rapid decay of the dislocation density leads to many highly non-trivial features of the stress distributions in such layers and study in detail the dependence of these features on the average grain size. Finally we develop an analytical approach which allows us to predict the evolution of the stress variance with the grain size and compare analytical predictions with numerical results.

[Analysis of the influence of lower premolar rotation on TMJ stress distribution by finite element method].

PubMed

Zhang, Yuan; Wang, Mei-qing; Ling, Wei

2005-10-01

To evaluate the resultant differences of stress distribution in bilateral condyle when occlusal loads were changed with teeth rotation. A three-dimensional FEA model containing human TMJ and left lower second premolar was developed using commercial FEA software ANSYS. Lower second premolar was applied with ICO occlusal loading in the load case 1. According to the same upper dentition in the load case 2, lower premolar was applied with occlusal loading when it was rotated 30 degree counter-clockwise in Frankfort horizontal plane level. In this two load cases,the different stress distributions of the condyle was investigated. The stress distribution of loading side condyle had changed abnormally when premolar rotation was performed. It had showed more disorderly than ICO loading in load case 1. In load case 1 the maximum main stress and Von Mises stress values increased from medial pole to lateral pole. In load case 2,the stress values mainly decreased from medial pole to lateral pole, but along the path there were some parts with values-increasing. The stress values of bilateral condyle in load case 2 were lower than that in load case 1, especially for the stress values of the opposite condyle. The stress distribution of loading side condyle got in disorder resulting from rotation of unilateral lower premolar.

The predictive value of chronic kidney disease for assessing cardiovascular events under consideration of pretest probability for coronary artery disease in patients who underwent stress myocardial perfusion imaging.

PubMed

Furuhashi, Tatsuhiko; Moroi, Masao; Joki, Nobuhiko; Hase, Hiroki; Masai, Hirofumi; Kunimasa, Taeko; Fukuda, Hiroshi; Sugi, Kaoru

2013-02-01

Pretest probability of coronary artery disease (CAD) facilitates diagnosis and risk stratification of CAD. Stress myocardial perfusion imaging (MPI) and chronic kidney disease (CKD) are established major predictors of cardiovascular events. However, the role of CKD to assess pretest probability of CAD has been unclear. This study evaluates the role of CKD to assess the predictive value of cardiovascular events under consideration of pretest probability in patients who underwent stress MPI. Patients with no history of CAD underwent stress MPI (n = 310; male = 166; age = 70; CKD = 111; low/intermediate/high pretest probability = 17/194/99) and were followed for 24 months. Cardiovascular events included cardiac death and nonfatal acute coronary syndrome. Cardiovascular events occurred in 15 of the 310 patients (4.8 %), but not in those with low pretest probability which included 2 CKD patients. In patients with intermediate to high pretest probability (n = 293), multivariate Cox regression analysis identified only CKD [hazard ratio (HR) = 4.88; P = 0.022) and summed stress score of stress MPI (HR = 1.50; P < 0.001) as independent and significant predictors of cardiovascular events. Cardiovascular events were not observed in patients with low pretest probability. In patients with intermediate to high pretest probability, CKD and stress MPI are independent predictors of cardiovascular events considering the pretest probability of CAD in patients with no history of CAD. In assessing pretest probability of CAD, CKD might be an important factor for assessing future cardiovascular prognosis.

The allowance exchange - ALEX

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mangis, J.K.; Miller, C.; Nicholas, J.

1997-12-31

The success of market approaches to pollution control in reducing the cost of compliance with environmental regulation, has insured the inclusion of emissions trading programs in current and future regulatory programs. As these environmental trading programs multiply, (SO{sub 2}, NO{sub x}, Ozone Precursors, Wetlands, CO{sub 2} and others), utility companies will need a central location to buy, sell, and trade these allowances to meet regulatory needs. In response, SAIC has designed and prototyped an electronic trading system that can provide a common forum for the location and exchange of environmental allowances, marketable permits, and other market based instruments for environmentalmore » management. SAIC intends to open and operate the Allowance Exchange (ALEX) for the trading of all environmental allowances, associated with the operation of electric utilities, as a service to the nation, the industry, and the environmental community.« less

SKA2 Methylation is Involved in Cortisol Stress Reactivity and Predicts the Development of Post-Traumatic Stress Disorder (PTSD) After Military Deployment

PubMed Central

Boks, Marco P; Rutten, Bart P F; Geuze, Elbert; Houtepen, Lotte C; Vermetten, Eric; Kaminsky, Zachary; Vinkers, Christiaan H

2016-01-01

Genomic variation in the SKA2 gene has recently been identified as a promising suicide biomarker. In light of its role in glucocorticoid receptor transactivation, we investigated whether SKA2 DNA methylation influences cortisol stress reactivity and is involved in the development of post-traumatic stress disorder (PTSD). Increased SKA2 methylation was significantly associated with lower cortisol stress reactivity in 85 healthy individuals exposed to the Trier Social Stress Test (B=−173.40, t=−2.324, p-value=0.023). Next, we observed that longitudinal decreases in SKA2 methylation after deployment were associated with the emergence of post-deployment PTSD symptoms in a Dutch military cohort (N=93; B=−0.054, t=−3.706, p-value=3.66 × 10−4). In contrast, exposure to traumatic stress during deployment by itself resulted in longitudinal increases in SKA2 methylation (B=0.037, t=4.173, p-value=6.98 × 10−5). Using pre-deployment SKA2 methylation levels and childhood trauma exposure, we found that the previously published suicide prediction rule significantly predicted post-deployment PTSD symptoms (AUC=0.66, 95% CI: 0.53–0.79) with an optimal sensitivity of 0.81 and specificity of 0.91. Permutation analysis using random methylation loci supported these findings. Together, these data establish the importance of SKA2 for cortisol stress responsivity and the development of PTSD and provide further evidence that SKA2 is a promising biomarker for stress-related disorders including PTSD. PMID:26361058

Pre-slaughter stress and pork quality

NASA Astrophysics Data System (ADS)

Stajković, S.; Teodorović, V.; Baltić, M.; Karabasil, N.

2017-09-01

Stress is an inevitable consequence of handling of animals for slaughter. Stress conditions during transport, lairage and at slaughter induce undesirable effects on the end quality of meat such as pale, soft, exudative meat and dark firm dry meat. Hence, it is very important to define appropriate parameters for objective assessment of level of stress. Attempts to define measures of stress have been difficult and no physiological parameter has been successfully used to evaluate stress situations. One physiological change in swine associated with animal handling stress and with pork quality is an increase in blood lactate concentration. Plasma cortisol was thought to be an appropriate indicator of stress, but the concentration was not consistently changed by different stressors. Therefore, finding alternative parameters reacting to stressors, such as acute phase proteins, would be of great value for the objective evaluation of level of stress and meat quality. As the stress during pre-slaughter handling is unavoidable, the final goal is to improve transport and slaughter conditions for the animal and, as a consequence, meat quality and animal welfare.

Determination of Multiple Near-Surface Residual Stress Components in Laser Peened Aluminum Alloy via the Contour Method

NASA Astrophysics Data System (ADS)

Toparli, M. Burak; Fitzpatrick, Michael E.; Gungor, Salih

2015-09-01

In this study, residual stress fields, including the near-surface residual stresses, were determined for an Al7050-T7451 sample after laser peening. The contour method was applied to measure one component of the residual stress, and the relaxed stresses on the cut surfaces were then measured by X-ray diffraction. This allowed calculation of the three orthogonal stress components using the superposition principle. The near-surface results were validated with results from incremental hole drilling and conventional X-ray diffraction. The results demonstrate that multiple residual stress components can be determined using a combination of the contour method and another technique. If the measured stress components are congruent with the principal stress axes in the sample, then this allows for determination of the complete stress tensor.

Quantifying Livestock Heat Stress Impacts in the Sahel

NASA Astrophysics Data System (ADS)

Broman, D.; Rajagopalan, B.; Hopson, T. M.

2014-12-01

Livestock heat stress, especially in regions of the developing world with limited adaptive capacity, has a largely unquantified impact on food supply. Though dominated by ambient air temperature, relative humidity, wind speed, and solar radiation all affect heat stress, which can decrease livestock growth, milk production, reproduction rates, and mortality. Indices like the thermal-humidity index (THI) are used to quantify the heat stress experienced from climate variables. Livestock experience differing impacts at different index critical thresholds that are empirically determined and specific to species and breed. This lack of understanding has been highlighted in several studies with a limited knowledge of the critical thresholds of heat stress in native livestock breeds, as well as the current and future impact of heat stress,. As adaptation and mitigation strategies to climate change depend on a solid quantitative foundation, this knowledge gap has limited such efforts. To address the lack of study, we have investigated heat stress impacts in the pastoral system of Sub-Saharan West Africa. We used a stochastic weather generator to quantify both the historic and future variability of heat stress. This approach models temperature, relative humidity, and precipitation, the climate variables controlling heat stress. Incorporating large-scale climate as covariates into this framework provides a better historical fit and allows us to include future CMIP5 GCM projections to examine the climate change impacts on heat stress. Health and production data allow us to examine the influence of this variability on livestock directly, and are considered in conjunction with the confounding impacts of fodder and water access. This understanding provides useful information to decision makers looking to mitigate the impacts of climate change and can provide useful seasonal forecasts of heat stress risk. A comparison of the current and future heat stress conditions based on

Thermal-stress-free fasteners for joining orthotropic materials

NASA Technical Reports Server (NTRS)

Blosser, M. L.

1987-01-01

Hot structures fabricated from orthotropic materials are an attractive design option for future high speed vehicles. Joining subassemblies of these materials with standard cylindrical fasteners can lead to loose joints or highly stressed joints due to thermal stress. A method has been developed to eliminate thermal stresses and maintain a tight joint by shaping the fastener and mating hole. This method allows both materials (fastener and structure), with different coefficients of thermal expansion (CTEs) in each of the three material directions, to expand freely with temperature yet remain in contact. For the assumptions made in the analysis, the joint will remain snug, yet free of thermal stress at any temperature. Finite element analysis was used to verify several thermal-stress-free fasteners and to show that conical fasteners, which are thermal-stress-free for isotropic materials, can reduce thermal stresses for transversely isotropic materials compared to a cylindrical fastener. Equations for thermal-stress-free shapes are presented and typical fastener shapes are shown.

Overseas Cost of Living Allowances (COLA)

Science.gov Websites

) Government Meal Rate Meal Tickets Mileage Rates Overseas Cost of Living Allowances (COLA) Calculation of Reporting Procedures Station Allowance Changes Programs & Services > Allowances > Overseas Cost of Allowances Submit Questions Overseas Cost of Living Allowances (COLA) The Overseas Cost of Living Allowance

[Brief Scale of Vocational Stress (BSVS)].

PubMed

Dudek, Bohdan; Hauk, Mateusz

2010-01-01

Stress at work is one of the basic notions in applied psychology. There are many approaches to vocational stress presented in the scientific literature and in a number of articles. There is also a variety of methods dedicated to stress assessment. One of the interesting examples is "The Stress in General Scale" developed by Stanton and his coworkers. This questionnaire consists of two subscales named: Pressure and Threat. The operationalisation of the stress at work phenomenon proposed by the authors seems to be very interesting (it allows for quick and easy diagnosis of the problem). That is why, we have decided to prepare the Polish adaptation of this questionnaire. The paper presents individual stages of the adaptation study, which has resulted in the construction of a 26-item questionnaire of the five-factor structure (factor I--Pressure, factor II--Attractiveness, factor III--Risk, factor IV--Liking, factor V--Calm), and the preliminary psychometric properties seem to be satisfactory (e.g. Cronbach alpha = 0.86).

Autonomous stress imaging cores: from concept to reality

NASA Astrophysics Data System (ADS)

van der Velden, Stephen; Rajic, Nik; Brooks, Chris; Galea, Steve

2016-04-01

The historical reliance of thermoelastic stress analysis on cooled infrared detection has created significant cost and practical impediments to the widespread use of this powerful full-field stress measurement technique. The emergence of low-cost microbolometers as a practical alternative has allowed for an expansion of the traditional role of thermoelastic stress analysis, and raises the possibility that it may in future become a viable structural health monitoring modality. Experimental results are shown to confirm that high resolution stress imagery can be obtained from an uncooled thermal camera core significantly smaller than any infrared imaging device previously applied to TSA. The paper provides a summary of progress toward the development of an autonomous stress-imaging capability based on this core.

Anatomical evaluation and stress distribution of intact canine femur.

PubMed

Verim, Ozgur; Tasgetiren, Suleyman; Er, Mehmet S; Ozdemir, Vural; Yuran, Ahmet F

2013-03-01

In the biomedical field, three-dimensional (3D) modeling and analysis of bones and tissues has steadily gained in importance. The aim of this study was to produce more accurate 3D models of the canine femur derived from computed tomography (CT) data by using several modeling software programs and two different methods. The accuracy of the analysis depends on the modeling process and the right boundary conditions. Solidworks, Rapidform, Inventor, and 3DsMax software programs were used to create 3D models. Data derived from CT were converted into 3D models using two different methods: in the first, 3D models were generated using boundary lines, while in the second, 3D models were generated using point clouds. Stress analyses in the models were made by ANSYS v12, also considering any muscle forces acting on the canine femur. When stress values and statistical values were taken into consideration, more accurate models were obtained with the point cloud method. It was found that the maximum von Mises stress on the canine femur shaft was 34.8 MPa. Stress and accuracy values were obtained from the model formed using the Rapidform software. The values obtained were similar to those in other studies in the literature. Copyright © 2012 John Wiley & Sons, Ltd.

Stress Without Distress

ERIC Educational Resources Information Center

Selye, Hans

1977-01-01

The author asserts that a way of life based on understanding man's responses to stress and constant change is the only way that leads out of the present jungle of conflicting judgements about right and wrong, justice and injustice, in which a sense of values has become entangled and obscured. (Author)

26 CFR 1.612-2 - Allowable capital additions in case of mines.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 26 Internal Revenue 7 2010-04-01 2010-04-01 true Allowable capital additions in case of mines. 1... in case of mines. (a) In general. Expenditures for improvements and for replacements, not including... the recession of the working faces of the mine and which: (1) Do not increase the value of the mine...

Stress Related Fracturing in Dimension Stone Quarries

NASA Astrophysics Data System (ADS)

Hamdi Deliormanli, Ahmet; Maerz, Norbert H.

2016-10-01

In Missouri, the horizontal stresses (pressures) in the near surface rock are uncommonly high. While the vertical stresses in rock are simply a function of the weight of the overlying rock, near surface stresses can be many times higher. The near surface horizontal stresses can be in excess of 5 times greater than the vertical stresses. In this research, Flatjack method was used to measure horizontal stress in Red Granite Quarry in Missouri. The flat jack method is an approved method of measuring ground stresses. A saw cut is used to “relax” the stress in the ground by allowing the rock to deform inwards the cut. A hydraulic flat jack is used to inflate the slot; to push the rock back to its stressed position, as measured by a strain gauge on either side of the slot. The pressure in the jack, when the rock is exactly back to its original position, is equal to the ground stress before the saw cut was made. According to the results, present production direction for each pit is not good because the maximum stress direction is perpendicular with production direction. This case causes unintentional breakage results in the loss rock. The results show that production direction should be changed.

Determining the minimum in situ stress from hydraulic fracturing through perforations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warpinski, N.R.

Hydraulic fracture stress measurements have been performed through perforations at depths from 1310 to 2470 m at the US Department of Energy's Multiwell Experiment site. The results of over sixty stress tests conducted through perforations have shown that small-volume hydraulic fractures generally provide an accurate, reproducible measurement of the minimum in situ stress. However, unusual behavior can occur in some tests and techniques to evaluate the behavior are suggested. Unclear instantaneous shut-in pressures, which are found on occasional tests, are difficult to evaluate, but the problem appears to be a complex stress state; reprocessing the data using log-log or othermore » functions does not necessarily provide the correct stress value. The possible error in such tests should be assessed from the original pressure-time data and not the reprocessing techniques. Stress results show that the stress distribution is dependent on lithology at this site; mudstones, shales and other nonreservoir rocks generally have a near-lithostatic stress, while sandstones have a considerably lower minimum stress value. 30 refs., 18 figs., 4 tabs.« less

Value of Exercise Stress Electrocardiography for Risk Stratification in Patients With Suspected or Known Coronary Artery Disease in the Era of Advanced Imaging Technologies

PubMed Central

Bourque, Jamieson M.; Beller, George A.

2015-01-01

Exercise stress electrocardiography (ExECG) is underutilized as the initial test modality in patients with interpretable electrocardiograms able to exercise. Although, stress myocardial imaging techniques provide valuable diagnostic and prognostic information, variables derived from ExECG can yield substantial data for risk stratification, either supplementary to imaging variables, or without concurrent imaging. In addition to exercise-induced ischemic ST depression, such markers as ST segment elevation in lead AVR, abnormal heart rate recovery post-exercise, failure to achieve target heart rate, and poor exercise capacity improve risk stratification of ExECG. For example, patients achieving ≥10 METS on ExECG have a very low prevalence of inducible ischemia and an excellent prognosis. In contrast, cardiac imaging techniques add diagnostic and prognostic value in higher risk populations (e.g. poor functional capacity, diabetes, chronic kidney disease). Optimal test selection for symptomatic patients with suspected coronary artery disease requires a patient-centered approach factoring in the risk/benefit ratio and cost-effectiveness. PMID:26563861

Diagnostic Value of Electrocardiogram in Predicting Exaggerated Blood Pressure Response to Exercise Stress Testing.

PubMed

Eshraghi, Ali; Ebdali, Reyhaneh Takalloo; Sajjadi, Seyed Sajed; Golnezhad, Reza

2016-08-01

It is believed that an exaggerated blood pressure response (EBPR) to exercise stress test is associated with a higher risk of cardiovascular events. It is also assumed that QT dispersion (QT-d), which was originally proposed to measure the spatial dispersion of ventricular recovery times, may have a relationship to cardiovascular events. The objective of this study was to examine the difference of changes in QT-d, Maxi-QT, Mini-QT, and QT-c (corrected QT interval) of the electrocardiogram in two groups of patients with exaggerated blood pressure responses (EBPR group) and normal responses (control group) to exercise testing. Also, the diagnostic value of each of these criteria in the prediction of EBPR was studied. This cross-sectional study was conducted from May 2015 to February 2016 on patients suspected of coronary artery disease (CAD) undergoing exercise testing who had been referred to Ghaem and Imam Reza hospitals in Mashhad (Iran). All patients underwent a treadmill exercise test with the 12-lead ECG, which was optically scanned and digitized for analysis of QT-d, QT max, and QT min. Patients were divided into two groups of normal and EBPR to exercise testing. QT changes of ECG were compared between the two groups, and the diagnostic accuracy of QT variables for prediction of EBPR to exercise testing was studied. A multiple linear regression analysis (MLR), Pearson Chi-qquare, independent samples t-test, and receiver operating characteristic (ROC) curve were used as statistical methods in IBM SPSS version 19. Sixty patients (55% male) with a mean age of 50.48 ± 10.89 years were studied in two groups of normal (n=30) and exaggerated blood pressure response (n=30) to exercise testing. Maximum QT and QT dispersion were statistically different in individuals' exaggerated blood pressure response to exercise stress test (p < 0.05). The logistic regression analysis revealed that none of our parameters predicted the EBPR. The ROC curve showed that 50 and 345

Determination of Residual Stress Distributions in Polycrystalline Alumina using Fluorescence Microscopy

PubMed Central

Michaels, Chris A.; Cook, Robert F.

2016-01-01

Maps of residual stress distributions arising from anisotropic thermal expansion effects in a polycrystalline alumina are generated using fluorescence microscopy. The shifts of both the R1 and R2 ruby fluorescence lines of Cr in alumina are used to create maps with sub-µm resolution of either the local mean and shear stresses or local crystallographic a- and c-stresses in the material, with approximately ± 1 MPa stress resolution. The use of single crystal control materials and explicit correction for temperature and composition effects on line shifts enabled determination of the absolute values and distributions of values of stresses. Temperature correction is shown to be critical in absolute stress determination. Experimental determinations of average stress parameters in the mapped structure are consistent with assumed equilibrium conditions and with integrated large-area measurements. Average crystallographic stresses of order hundreds of MPa are determined with characteristic distribution widths of tens of MPa. The stress distributions reflect contributions from individual clusters of stress in the structure; the cluster size is somewhat larger than the grain size. An example application of the use of stress maps is shown in the calculation of stress-intensity factors for fracture in the residual stress field. PMID:27563163

The Value of Concentrating Solar Power and Thermal Energy Storage

DOE PAGES

Sioshansi, Ramteen; Denholm, Paul

2010-06-14

Our paper examines the value of concentrating solar power (CSP) and thermal energy storage (TES) in a number of regions in the southwestern United States. Our analysis also shows that TES can increase the value of CSP by allowing more thermal energy from a CSP plant's solar field to be used, allowing a CSP plant to accommodate a larger solar field, and by allowing CSP generation to be shifted to hours with higher energy prices. We also analyze the sensitivity of this value to a number of factors, including the optimization period, price and solar forecasting, ancillary service sales, andmore » dry cooling of the CSP plant, and also estimate the capacity value of a CSP plant with TES. We further discuss the value of CSP plants and TES net of capital costs.« less

Lithospheric Stress Tensor from Gravity and Lithospheric Structure Models

NASA Astrophysics Data System (ADS)

Eshagh, Mehdi; Tenzer, Robert

2017-07-01

In this study we investigate the lithospheric stresses computed from the gravity and lithospheric structure models. The functional relation between the lithospheric stress tensor and the gravity field parameters is formulated based on solving the boundary-value problem of elasticity in order to determine the propagation of stresses inside the lithosphere, while assuming the horizontal shear stress components (computed at the base of the lithosphere) as lower boundary values for solving this problem. We further suppress the signature of global mantle flow in the stress spectrum by subtracting the long-wavelength harmonics (below the degree of 13). This numerical scheme is applied to compute the normal and shear stress tensor components globally at the Moho interface. The results reveal that most of the lithospheric stresses are accumulated along active convergent tectonic margins of oceanic subductions and along continent-to-continent tectonic plate collisions. These results indicate that, aside from a frictional drag caused by mantle convection, the largest stresses within the lithosphere are induced by subduction slab pull forces on the side of subducted lithosphere, which are coupled by slightly less pronounced stresses (on the side of overriding lithospheric plate) possibly attributed to trench suction. Our results also show the presence of (intra-plate) lithospheric loading stresses along Hawaii islands. The signature of ridge push (along divergent tectonic margins) and basal shear traction resistive forces is not clearly manifested at the investigated stress spectrum (between the degrees from 13 to 180).

Cumulative life stress in chronic fatigue syndrome.

PubMed

Nater, Urs M; Maloney, Elizabeth; Heim, Christine; Reeves, William C

2011-09-30

We studied the impact of cumulative life stress on CFS in a population-based study. We found that exposure to stressors was significantly more common in persons with CFS compared to NF controls; those with CFS reported experiencing significantly higher levels of psychological distress. Also, post-traumatic stress disorder was significantly more common in people with CFS. These results not only corroborate findings from other studies but, importantly, extend those by: a) measuring a comprehensive spectrum of stress variables, b) for the first time presenting data on stress in a population-based study, thus minimizing the effects of recruitment bias, and c) diagnosing CFS by means of standardized, validated scales, thus allowing replication and extension of our findings. Stress may be an important factor in the pathophysiology of CFS. Consequently, future studies should provide a more detailed understanding of the processes that lead from stress to CFS using longitudinal designs. Published by Elsevier Ireland Ltd.

Salivary amylase and stress during stressful environment: three Mars analog mission crews study.

PubMed

Rai, Balwant; Kaur, Jasdeep; Foing, Bernard H

2012-06-14

After the establishment of the space age physicians, human factors engineers, neurologist and psychologists and their special attention to work on people's capability to meet up the physical, psychological, neuroscience and interpersonal strains of working in space, it has been regarded as an issue that seeks urgent consideration. Not study was conducted on effect of simulated Mars analog environment on stress and salivary amylase. So, this study aimed to confirm whether salivary amylase is act as stress biomarker in crew members who took part in Mars analog mission in an isolated and stressful environment. The 18 crew members were selected who took part in Mars Analog Research Station, Utah. Salivary amylase was measured using a biosensor of salivary amylase monitor and State-Trait Anxiety Inventory score at pre-extravehicular activity, post-extravehicular activity and on before mission. The state and trait anxiety scores at pre-extravehicular activity for each commander were elevated as compared to after extravehicular activity. There were significant differences in the state and trait anxiety scores between before extravehicular activity and after extravehicular activity of Commander and other members, also there were significant differences in values of before-extravehicular activity between commanders and other members. There were significant differences in values of salivary amylase at before extravehicular activity and after extravehicular activity between commander group and other members. There was significant correlation between salivary amylase and state and trait anxiety scores in all groups. Measuring salivary amylase level could be useful for stress assessment of crew members and population working in a stressful and isolated environment. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Work related stress and blood glucose levels.

PubMed

Sancini, A; Ricci, S; Tomei, F; Sacco, C; Pacchiarotti, A; Nardone, N; Ricci, P; Suppi, A; De Cesare, D P; Anzelmo, V; Giubilati, R; Pimpinella, B; Rosati, M V; Tomei, G

2017-01-01

The aim of the study is to evaluate work-related subjective stress in a group of workers on a major Italian company in the field of healthcare through the administration of a valid "questionnaire-tool indicator" (HSE Indicator Tool), and to analyze any correlation between stress levels taken from questionnaire scores and blood glucose values. We studied a final sample consisting of 241 subjects with different tasks. The HSE questionnaire - made up of 35 items (divided into 7 organizational dimensions) with 5 possible answers - has been distributed to all the subjects in occasion of the health surveillance examinations provided by law. The questionnaire was then analyzed using its specific software to process the results related to the 7 dimensions. These results were compared using the Pearson correlation and multiple linear regression with the blood glucose values obtained from each subject. From the analysis of the data the following areas resulted critical, in other words linked to an intermediate (yellow area) or high (red area) condition of stress: sustain from managers, sustain from colleagues, quality of relationships and professional changes. A significant positive correlation (p <0.05) between the mean values of all critical areas and the concentrations of glucose values have been highlighted with the correlation index of Pearson. Multiple linear regression confirmed these findings, showing that the critical dimensions resulting from the questionnaire were the significant variables that can increase the levels of blood glucose. The preliminary results indicate that perceived work stress can be statistically associated with increased levels of blood glucose.

Stress fracture of the second proximal phalanx of the foot in teenage athletes: Unrecognized location of stress fracture.

PubMed

Yamaguchi, Satoshi; Taketomi, Shuji; Funakoshi, Yusei; Tsuchiya, Kan; Akagi, Ryuichiro; Kimura, Seiji; Sadamasu, Aya; Ohtori, Seiji

2017-10-01

Adolescent athletes are a high-risk population for stress fractures. We report four cases of stress fractures of the second proximal phalanx, which had not been previously diagnosed as the location of the stress fracture of the foot, in teenage athletes. All fractures were on the plantar side of the proximal phalangeal base, and the oblique images of the plain radiograph clearly depicted the fractures. Notably, three out of the four patients had histories of stress fracture of other locations. While three athletes with acute cases were able to make an early return to play with simple conservative management, the chronic case required surgical treatment for this rare injury. Although a rare injury, it is important that clinicians be aware of this type of stress fracture, as a timely diagnosis can avoid the need for surgical treatment and allow an early return to play.

Stress at work: development of the Stress Perception Questionnaire of Rome (SPQR), an ad hoc questionnaire for multidimensional assessment of work related stress.

PubMed

Cinti, M E; Cannavò, M; Fioravanti, M

2017-01-01

Stress is an emotional condition, mostly experienced as negative, initially identified and defined by Selye in the mid-thirties of the last Century. Since the first definition, stress concerns the adaptation pro- cess mostly related to environmental changes. An application of stress focuses on the evaluation of its interference on work conditions, and the scientific evidence on work related stress is very ample and rich. We are proposing a new ad hoc questionnaire for the multidimensional assessment of work related stress, called Stress Perception Question- naire of Rome (SPQR) composed of 50 items. The development of this questionnaire is based on a multi-step process: a) Identification of all the relevant topics to work related stress and areas in the scientific evidence and their transformation on specific contents of 60 tentative items; b) Exploratory factor analysis aimed to identify the best items (50) which could guarantee the maximum convergence on single scales (8), and the minimum redundancy between scales; c) Validation of the 8 scales' structure by a confirmatory factor analysis (fully achieved); d) Factor analysis for a second level factor resulting in a single factor identified as the questionnaire total score (Stress Score); d) Reliability analysis of the questionnaire total score and the single scale scores (at optimum level); e) Validation by external criteria of work related stress identified in the presence of personal violence episodes experienced by a group of health workers with different professional profiles and from two different hospitals in Rome. Our results show that the SPQR is a useful and sensitive tool for assessing the presence of emotional stress related problems identifiable in a work environment. The advantage of this questionnaire is that it allows for a multidimensional description of the different components of this problematic area besides its ability to quantify the overall stress level of those who have been administered

The Tangle of Student Allowances.

ERIC Educational Resources Information Center

Thomson, Norman J.

1980-01-01

A discussion of the distribution of student financial aid in Australia focuses on these issues: direct vs. indirect payment to students; inequality in living allowances given to secondary and postsecondary students; and distribution of expense allowances by state government and living allowances by the Commonwealth. (MSE)

30 CFR 1206.179 - What general requirements regarding processing allowances apply to me?

Code of Federal Regulations, 2014 CFR

2014-07-01

..., DEPARTMENT OF THE INTERIOR NATURAL RESOURCES REVENUE PRODUCT VALUATION Indian Gas Processing Allowances... gas plant product under § 1206.174, you may deduct from value the reasonable actual costs of processing. (b) You must allocate processing costs among the gas plant products. You must determine a...

30 CFR 1206.179 - What general requirements regarding processing allowances apply to me?

Code of Federal Regulations, 2013 CFR

2013-07-01

..., DEPARTMENT OF THE INTERIOR NATURAL RESOURCES REVENUE PRODUCT VALUATION Indian Gas Processing Allowances... gas plant product under § 1206.174, you may deduct from value the reasonable actual costs of processing. (b) You must allocate processing costs among the gas plant products. You must determine a...

30 CFR 1206.179 - What general requirements regarding processing allowances apply to me?

Code of Federal Regulations, 2012 CFR

2012-07-01

..., DEPARTMENT OF THE INTERIOR NATURAL RESOURCES REVENUE PRODUCT VALUATION Indian Gas Processing Allowances... gas plant product under § 1206.174, you may deduct from value the reasonable actual costs of processing. (b) You must allocate processing costs among the gas plant products. You must determine a...

Comparison of beverage consumption in adult populations from three different countries: do the international reference values allow establishing the adequacy of water and beverage intakes?

PubMed

Nissensohn, Mariela; Fuentes Lugo, Daniel; Serra-Majem, Lluis

2016-07-13

contrast with 21% of women, do satisfy the EFSA criterion. The IOM criterion reaches even less with higher recommended values for daily intake. In contrast, 60% of the American population reached the recommended intake of the IOM criterion. However, available data did not allow calculating the percentage reached by the EFSA criterion. Data from the Mexican study did not permit conducting comparisons with IOM or with EFSA. However, the water density criteria (mL/kcal) was higher than 1. There is a notable difference between all three populations in terms of TWI. Furthermore, within the same population, values of adequacy of TWI changed signifi cantly when they were assessed using different criteria. More scientifi c evidence is required for the production of better defined water intake recommendations in the future as well as more studies focusing on beverage consumption patterns in different settings.

Depth dependent stress revealed by aftershocks

NASA Astrophysics Data System (ADS)

Narteau, C.; Shebalin, P.

2017-12-01

Aftershocks occur in response to perturbations of the state of stress induced either by earthquakes or human activities. Along major strike-slip fault segments of the San Andreas fault system, the time-delay before the onset of the power-law aftershock decay rate (the c-value) varies by three orders of magnitude in the first twenty kilometers below the surface. Despite the influence of the lithostatic stress, there is no continuous change in c-value with respect to depth. Instead, two decay phases are separated by an abrupt increase at an intermediate depth range of 2 to 5 km. This transitional regime is the only one observed in fluid-injection-induced seismic areas. This provides strong evidence for the role of fluid and a porosity reduction mechanism at depth of few kilometers in active fault zones. Aftershock statistics can then be used to predict the evolution the differential shear stress with depth until the brittle-ductile transition is reached.

Retrospective stress-forecasting of earthquakes

NASA Astrophysics Data System (ADS)

Gao, Yuan; Crampin, Stuart

2015-04-01

Observations of changes in azimuthally varying shear-wave splitting (SWS) above swarms of small earthquakes monitor stress-induced changes to the stress-aligned vertical microcracks pervading the upper crust, lower crust, and uppermost ~400km of the mantle. (The microcracks are intergranular films of hydrolysed melt in the mantle.) Earthquakes release stress, and an appropriate amount of stress for the relevant magnitude must accumulate before each event. Iceland is on an extension of the Mid-Atlantic Ridge, where two transform zones, uniquely run onshore. These onshore transform zones provide semi-continuous swarms of small earthquakes, which are the only place worldwide where SWS can be routinely monitored. Elsewhere SWS must be monitored above temporally-active occasional swarms of small earthquakes, or in infrequent SKS and other teleseismic reflections from the mantle. Observations of changes in SWS time-delays are attributed to stress-induced changes in crack aspect-ratios allowing stress-accumulation and stress-relaxation to be identified. Monitoring SWS in SW Iceland in 1988, stress-accumulation before an impending earthquake was recognised and emails were exchanged between the University of Edinburgh (EU) and the Iceland Meteorological Office (IMO). On 10th November 1988, EU emailed IMO that a M5 earthquake could occur soon on a seismically-active fault plane where seismicity was still continuing following a M5.1 earthquake six-months earlier. Three-days later, IMO emailed EU that a M5 earthquake had just occurred on the specified fault-plane. We suggest this is a successful earthquake stress-forecast, where we refer to the procedure as stress-forecasting earthquakes as opposed to predicting or forecasting to emphasise the different formalism. Lack of funds has prevented us monitoring SWS on Iceland seismograms, however, we have identified similar characteristic behaviour of SWS time-delays above swarms of small earthquakes which have enabled us to

Static-stress analysis of dual-axis safety vessel

NASA Astrophysics Data System (ADS)

Bultman, D. H.

1992-11-01

An 8 ft diameter safety vessel, made of HSLA-100 steel, is evaluated to determine its ability to contain the quasi-static residual pressure from a high explosive (HE) blast. The safety vessel is designed for use with the Dual-Axis Radiographic Hydrotest (DARHT) facility being developed at Los Alamos National Laboratory. A smaller confinement vessel fits inside the safety vessel and contains the actual explosion, and the safety vessel functions as a second layer of containment in the unlikely case of a confinement vessel leak. The safety vessel is analyzed as a pressure vessel based on the ASME Boiler and Pressure Vessel Code, Section 8, Division 1, and the Welding Research Council Bulletin, WRC107. Combined stresses that result from internal pressure and external loads on nozzles are calculated and compared to the allowable stresses for HSLA-100 steel. Results confirm that the shell and nozzle components are adequately designed for a static pressure of 830 psi, plus the maximum expected external loads. Shell stresses at the 'shell to nozzle' interface, produced from external loads on the nozzles, were less than 700 psi. The maximum combined stress resulting from the internal pressure plus external loads was 17,384 psi, which is significantly less than the allowable stress of 42,375 psi for HSLA-100 steel.

Low-Cost Detection of Thin Film Stress during Fabrication

NASA Technical Reports Server (NTRS)

Nabors, Sammy A.

2015-01-01

NASA's Marshall Space Flight Center has developed a simple, cost-effective optical method for thin film stress measurements during growth and/or subsequent annealing processes. Stress arising in thin film fabrication presents production challenges for electronic devices, sensors, and optical coatings; it can lead to substrate distortion and deformation, impacting the performance of thin film products. NASA's technique measures in-situ stress using a simple, noncontact fiber optic probe in the thin film vacuum deposition chamber. This enables real-time monitoring of stress during the fabrication process and allows for efficient control of deposition process parameters. By modifying process parameters in real time during fabrication, thin film stress can be optimized or controlled, improving thin film product performance.

Recovery from work-related stress: a randomized controlled trial of a stress management intervention in a clinical sample.

PubMed

Glasscock, David J; Carstensen, Ole; Dalgaard, Vita Ligaya

2018-05-28

Randomized controlled trials (RCTs) of interventions aimed at reducing work-related stress indicate that cognitive behavioural therapy (CBT) is more effective than other interventions. However, definitions of study populations are often unclear and there is a lack of interventions targeting both the individual and the workplace. The aim of this study was to determine whether a stress management intervention combining individual CBT and a workplace focus is superior to no treatment in the reduction of perceived stress and stress symptoms and time to lasting return to work (RTW) in a clinical sample. Patients with work-related stress reactions or adjustment disorders were randomly assigned to an intervention group (n = 57, 84.2% female) or a control group (n = 80, 83.8% female). Subjects were followed via questionnaires and register data. The intervention contained individual CBT and the offer of a workplace meeting. We examined intervention effects by analysing group differences in score changes on the Perceived Stress Scale (PSS-10) and the General Health Questionnaire (GHQ-30). We also tested if intervention led to faster lasting RTW. Mean baseline values of PSS were 24.79 in the intervention group and 23.26 in the control group while the corresponding values for GHQ were 21.3 and 20.27, respectively. There was a significant effect of time. 10 months after baseline, both groups reported less perceived stress and improved mental health. 4 months after baseline, we found significant treatment effects for both perceived stress and mental health. The difference in mean change in PSS after 4 months was - 3.09 (- 5.47, - 0.72), while for GHQ it was - 3.91 (- 7.15, - 0.68). There were no group differences in RTW. The intervention led to faster reductions in perceived stress and stress symptoms amongst patients with work-related stress reactions and adjustment disorders. 6 months after the intervention ended there were no longer differences between

Multimodal approach to identifying malingered posttraumatic stress disorder: a review.

PubMed

Ali, Shahid; Jabeen, Shagufta; Alam, Farzana

2015-01-01

The primary aim of this article is to aid clinicians in differentiating true posttraumatic stress disorder from malingered posttraumatic stress disorder. Posttraumatic stress disorder and malingering are defined, and prevalence rates are explored. Similarities and differences in diagnostic criteria between the fourth and fifth editions of the Diagnostic and Statistical Manual of Mental Disorders are described for posttraumatic stress disorder. Possible motivations for malingering posttraumatic stress disorder are discussed, and common characteristics of malingered posttraumatic stress disorder are described. A multimodal approach is described for evaluating posttraumatic stress disorder, including interview techniques, collection of collateral data, and psychometric and physiologic testing, that should allow clinicians to distinguish between those patients who are truly suffering from posttraumatic disorder and those who are malingering the illness.

Bitterness values for traditional tonic plants of southern Africa.

PubMed

Olivier, D K; van Wyk, B-E

2013-06-03

Bitterness values have been determined for southern African plant species that are traditionally used as tonics (imbizas or 'musa-pelo) to alleviate the symptoms of stress and a variety of ailments related to the digestive system. To measure and present, for the first time, the bitterness values of 15 of the best-known and most widely used tonic plants in southern Africa in order to find a rationale for their traditional use in improving appetite and treating digestive ailments. Most of the plants were found to be very bitter, with bitterness values comparable to those reported for internationally well-known bitter tonics such as Artemisia absynthium L. and Gentiana lutea L. The relatively high bitterness values obtained for all of the plants indicate that their alleged value in improving digestion and appetite may at least be partly ascribed to the bitter tonic (amarum) effect, i.e., the stimulation of gastric juices via the nervus vagus. It may be interesting to examine the chemical compounds responsible for the bitter taste, as well as the possible links between bitterness and the anecdotal anti-stress properties ascribed to these species. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Three-dimensional finite element analysis of the stress distribution pattern in a mandibular first molar tooth restored with five different restorative materials.

PubMed

D'souza, Kathleen Manuela; Aras, Meena Ajay

2017-01-01

Badly broken or structurally compromised posterior teeth are frequently associated with crown/root fracture. Numerous restorative materials have been used to fabricate indirect full-coverage restorations for such teeth. This study aims to evaluate and compare the effect of restorative materials on the stress distribution pattern in a mandibular first molar tooth, under varying loading conditions and to compare the stress distribution pattern in five commonly used indirect restorative materials. Five three-dimensional finite element models representing a mandibular first molar tooth restored with crowns of gold, porcelain fused to metal, composite (Artglass), alumina-based zirconia (In-Ceram Zirconia [ICZ]), and double-layered zirconia-based materials (zirconia core veneered with porcelain, Lava) were constructed, using a Finite Element Analysis Software (ANSYS version 10; ANSYS Inc., Canonsburg, PA, USA). Two loading conditions were applied, simulating maximum bite force of 600 N axially and normal masticatory bite force of 225 N axially and nonaxially. Both all-ceramic crowns allowed the least amount of stress distribution to the surrounding tooth structure. In maximum bite force-simulation test, alumina-based all-ceramic crown displayed the highest von Mises stresses (123.745 MPa). In the masticatory bite force-simulation test, both all-ceramic crowns (122.503-133.13 MPa) displayed the highest von Mises stresses. ICZ crown displayed the highest peak von Mises stress values under maximum and masticatory bite forces. ICZ and Lava crowns also allowed the least amount of stress distribution to the surrounding tooth structure, which is indicative of a favorable response of the underlying tooth structure to the overlying full-coverage indirect restorative material. These results suggest that ICZ and Lava crowns can be recommended for clinical use in cases of badly damaged teeth.

Taxing sulfur dioxide emission allowances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, G.L.

1993-09-15

The acid rain control program authorized by Title IV of the Clean Air Act Amendments of 1990 (CAAA) was designed to reduce the adverse effects of acid rain by limiting emissions of sulfur dioxide (SO[sub 2]) into the atmosphere. The program is a complex scheme involving the issuance, consumption, holding, and trading of emission allowances for SO[sub 2]. Not surprisingly, electric utilities will face federal income tax issues in connection with the program. Under the emission allowance program, the U.S. Environmental Protection Agency (EPA) will issue emission allowance to owners or operators of certain utility power plants at no costmore » to the recipients. An emission allowance is an authorization to emit one ton of SO[sub 2] during or after the calendar year for which it is issued. If a utility power plant subject to the program emits SO[sub 2] in excess of its allowances, the owner or operator will be subject to a penalty of $2,000 a ton, and must offset the excess emissions with allowances in the subsequent year. Allowances may be bought and sold. Phase I of the program begins January 1, 1995, and will apply to 110 utility generating units. Phase II takes effect January 1, 2000, and will include most electric utility generating units. EPA will withhold a specified number of allowances for direct sale and auction. The resulting proceeds will be paid to the utilities from which the allowances were withheld. The Internal Revenue Service (IRS) has provided somewhat limited guidance on several tax issues raised by the program. Significant tax issues and the positions articulated by the IRS (if any) are discussed in this article.« less

Finite element analysis to determine the stress distribution, displacement and safety factor on a microplate for the fractured jaw case

NASA Astrophysics Data System (ADS)

Pratama, Juan; Mahardika, Muslim

2018-03-01

Microplate is a connecting plate that can be used for jaw bone fixation. In the last two decades, microplate has been used so many times to help reconstruction of fractured jaw bone which is called mandibular bone or mandible bone. The plate is used to provide stable fixation of the fractured bone tissue during healing and reconstruction process. In this study Finite Element Analysis was used to predict the stress concentration and distribution on a microplate, displacement on the microplate and also to determine the safety factor of the microplate based on maximum allowable stress value, and finally to ascertain whether microplate is safe to use or not. The microplate was produced from punching process using titanium grade 1 (pure titanium) as material with a thickness of 500 µm. The results of the research indicated that the microplate was safe to use according to the maximum stress around the hole, displacement around the hole and also the safety factor of the microplate.

Lifetime impact on residual stress of EUV pellicle

NASA Astrophysics Data System (ADS)

Kim, Min-Woo; Lee, Sung-Gyu; Park, Eun-Sang; Oh, Hye-Keun

2017-10-01

Since EUV pellicle is very thin, It can be affected easily on its manufacturing process or the exposure process. The Pellicle has several types of stress, above all the pellicle has a residual stress from its manufacturing process. To determine the effect of residual stress on the pellicle, we calculated residual stress of several types of multi-layer pellicle by using formula. We could confirm that the residual stress has non-negligible values through the calculation results, and we obtained the thermal stress of each pellicle by using finite element method (FEM). we optimized the pellicle through comparison of total stress by plus the calculated residual stress and the thermal stress. As a result, since the p-Si core pellicle with B4C capping satisfies both high transparent and low total stress, we chose p-Si core pellicle with B4C capping as a suitable pellicle.

A climate stress-test of the financial system

NASA Astrophysics Data System (ADS)

Battiston, Stefano; Mandel, Antoine; Monasterolo, Irene; Schütze, Franziska; Visentin, Gabriele

2017-03-01

The urgency of estimating the impact of climate risks on the financial system is increasingly recognized among scholars and practitioners. By adopting a network approach to financial dependencies, we look at how climate policy risk might propagate through the financial system. We develop a network-based climate stress-test methodology and apply it to large Euro Area banks in a `green' and a `brown' scenario. We find that direct and indirect exposures to climate-policy-relevant sectors represent a large portion of investors' equity portfolios, especially for investment and pension funds. Additionally, the portion of banks' loan portfolios exposed to these sectors is comparable to banks' capital. Our results suggest that climate policy timing matters. An early and stable policy framework would allow for smooth asset value adjustments and lead to potential net winners and losers. In contrast, a late and abrupt policy framework could have adverse systemic consequences.

Determination of design allowable strength properties of elevated-temperature alloys. Part 1: Coated columbium alloys

NASA Technical Reports Server (NTRS)

Favor, R. J.; Maykuth, D. J.; Bartlett, E. S.; Mindlin, H.

1972-01-01

A program to determine the characteristics of two coated columbium alloy systems for spacecraft structures is discussed. The alloy was evaluated as coated base material, coated butt-welded material, and material thermal/pressure cycled prior to testing up to 30 cycles. Evaluation was by means of tensile tests covering the temperature range to 2400 F. Design allowables were computed and are presented as tables of data. The summary includes a room temperature property table, effect of temperature curves, and typical stress-strain curves.

Plate Versus Intramedullary Nail Fixation of Anterior Tibial Stress Fractures: A Biomechanical Study.

PubMed

Markolf, Keith L; Cheung, Edward; Joshi, Nirav B; Boguszewski, Daniel V; Petrigliano, Frank A; McAllister, David R

2016-06-01

Anterior midtibial stress fractures are an important clinical problem for patients engaged in high-intensity military activities or athletic training activities. When nonoperative treatment has failed, intramedullary (IM) nail and plate fixation are 2 surgical options used to arrest the progression of a fatigue fracture and allow bone healing. A plate will be more effective than an IM nail in preventing the opening of a simulated anterior midtibial stress fracture from tibial bending. Controlled laboratory study. Fresh-frozen human tibias were loaded by applying a pure bending moment in the sagittal plane. Thin transverse saw cuts, 50% and 75% of the depth of the anterior tibial cortex, were created at the midtibia to simulate a fatigue fracture. An extensometer spanning the defect was used to measure the fracture opening displacement (FOD) before and after the application of IM nail and plate fixation constructs. IM nails were tested without locking screws, with a proximal screw only, and with proximal and distal screws. Plates were tested with unlocked bicortical screws (standard compression plate) and locked bicortical screws; both plate constructs were tested with the plate edge placed 1 mm from the anterior tibial crest (anterior location) and 5 mm posterior to the crest. For the 75% saw cut depth, the mean FOD values for all IM nail constructs were 13% to 17% less than those for the saw cut alone; the use of locking screws had no significant effect on the FOD. The mean FOD values for all plate constructs were significantly less than those for all IM nail constructs. The mean FOD values for all plates were 28% to 46% less than those for the saw cut alone. Anterior plate placement significantly decreased mean FOD values for both compression and locked plate constructs, but the mean percentage reductions for locked and unlocked plates were not significantly different from each other for either plate placement. The percentage FOD reductions for all plate

Neural control of chronic stress adaptation

PubMed Central

Herman, James P.

2013-01-01

Stress initiates adaptive processes that allow the organism to physiologically cope with prolonged or intermittent exposure to real or perceived threats. A major component of this response is repeated activation of glucocorticoid secretion by the hypothalamo-pituitary-adrenocortical (HPA) axis, which promotes redistribution of energy in a wide range of organ systems, including the brain. Prolonged or cumulative increases in glucocorticoid secretion can reduce benefits afforded by enhanced stress reactivity and eventually become maladaptive. The long-term impact of stress is kept in check by the process of habituation, which reduces HPA axis responses upon repeated exposure to homotypic stressors and likely limits deleterious actions of prolonged glucocorticoid secretion. Habituation is regulated by limbic stress-regulatory sites, and is at least in part glucocorticoid feedback-dependent. Chronic stress also sensitizes reactivity to new stimuli. While sensitization may be important in maintaining response flexibility in response to new threats, it may also add to the cumulative impact of glucocorticoids on the brain and body. Finally, unpredictable or severe stress exposure may cause long-term and lasting dysregulation of the HPA axis, likely due to altered limbic control of stress effector pathways. Stress-related disorders, such as depression and PTSD, are accompanied by glucocorticoid imbalances and structural/ functional alterations in limbic circuits that resemble those seen following chronic stress, suggesting that inappropriate processing of stressful information may be part of the pathological process. PMID:23964212

Model for Stress-induced Protein Degradation in Lemna minor1

PubMed Central

Cooke, Robert J.; Roberts, Keith; Davies, David D.

1980-01-01

Transfer of Lemna minor fronds to adverse or stress conditions produces a large increase in the rate of protein degradation. Cycloheximide partially inhibits stress-induced protein degradation and also partially inhibits the protein degradation which occurs in the absence of stress. The increased protein degradation does not appear to be due to an increase in activity of soluble proteolytic enzymes. Biochemical evidence indicates that stress, perhaps acting via hormones, affects the permeability of certain membranes, particularly the tonoplast. A general model for stress-induced protein degradation is presented in which changes in membrane properties allow vacuolar proteolytic enzymes increased access to cytoplasmic proteins. PMID:16661588

Systematic survey of high-resolution b value imaging along Californian faults: Inference on asperities

NASA Astrophysics Data System (ADS)

Tormann, T.; Wiemer, S.; Mignan, A.

2014-03-01

Understanding and forecasting earthquake occurrences is presumably linked to understanding the stress distribution in the Earth's crust. This cannot be measured instrumentally with useful coverage. However, the size distribution of earthquakes, quantified by the Gutenberg-Richter b value, is possibly a proxy to differential stress conditions and could therewith act as a crude stress-meter wherever seismicity is observed. In this study, we improve the methodology of b value imaging for application to a high-resolution 3-D analysis of a complex fault network. In particular, we develop a distance-dependent sampling algorithm and introduce a linearity measure to restrict our output to those regions where the magnitude distribution strictly follows a power law. We assess the catalog completeness along the fault traces using the Bayesian Magnitude of Completeness method and systematically image b values for 243 major fault segments in California. We identify and report b value structures, revisiting previously published features, e.g., the Parkfield asperity, and documenting additional anomalies, e.g., along the San Andreas and Northridge faults. Combining local b values with local earthquake productivity rates, we derive probability maps for the annual potential of one or more M6 events as indicated by the microseismicity of the last three decades. We present a physical concept of how different stressing conditions along a fault surface may lead to b value variation and explain nonlinear frequency-magnitude distributions. Detailed spatial b value information and its physical interpretation can advance our understanding of earthquake occurrence and ideally lead to improved forecasting ability.

Improved Heat-Stress Algorithm

NASA Technical Reports Server (NTRS)

Teets, Edward H., Jr.; Fehn, Steven

2007-01-01

NASA Dryden presents an improved and automated site-specific algorithm for heat-stress approximation using standard atmospheric measurements routinely obtained from the Edwards Air Force Base weather detachment. Heat stress, which is the net heat load a worker may be exposed to, is officially measured using a thermal-environment monitoring system to calculate the wet-bulb globe temperature (WBGT). This instrument uses three independent thermometers to measure wet-bulb, dry-bulb, and the black-globe temperatures. By using these improvements, a more realistic WBGT estimation value can now be produced. This is extremely useful for researchers and other employees who are working on outdoor projects that are distant from the areas that the Web system monitors. Most importantly, the improved WBGT estimations will make outdoor work sites safer by reducing the likelihood of heat stress.

Gravitational stresses in anisotropic rock masses

USGS Publications Warehouse

Amadei, B.; Savage, W.Z.; Swolfs, H.S.

1987-01-01

This paper presents closed-form solutions for the stress field induced by gravity in anisotropic rock masses. These rocks are assumed to be laterally restrained and are modelled as a homogeneous, orthotropic or transversely isotropic, linearly elastic material. The analysis, constrained by the thermodynamic requirement that strain energy be positive definite, gives the following important result: inclusion of anisotropy broadens the range of permissible values of gravity-induced horizontal stresses. In fact, for some ranges of anisotropic rock properties, it is thermodynamically admissible for gravity-induced horizontal stresses to exceed the vertical stress component; this is not possible for the classical isotropic solution. Specific examples are presented to explore the nature of the gravity-induced stress field in anisotropic rocks and its dependence on the type, degree and orientation of anisotropy with respect to the horizontal ground surface. ?? 1987.

Influence of Endodontic Treatment on Systemic Oxidative Stress

PubMed Central

Inchingolo, Francesco; Marrelli, Massimo; Annibali, Susanna; Cristalli, Maria Paola; Dipalma, Gianna; Inchingolo, Alessio Danilo; Palladino, Antonio; Inchingolo, Angelo Michele; Gargari, Marco; Tatullo, Marco

2014-01-01

Introduction: An increased production of oxidizing species related to reactive oral diseases, such as chronic apical periodontitis, could have systemic implications such as an increase in cardiovascular morbidity. Based on this consideration, we conducted a prospective study to assess whether subjects affected by chronic periodontitis presented with higher values of oxidative stress than reference values before endodontic treatment, and whether endodontic treatment can reduce the oxidative imbalance and bring it back to normal in these subjects. Materials and methods: The authors recruited 2 groups of patients from private studies and dental clinics: these patients were recruited randomly. The oxidative balance in both patients with chronic apical periodontitis (CAP) and healthy control patients was determined by measuring the oxidant status, using an identification of the reactive oxygen metabolites (d-ROMs) test, while the antioxidant status in these patients was determined using a biological antioxidant potential (BAP) test. Both these tests were carried on plasma samples taken from enrolled patients. Values were measured both before the endodontic treatment of the patients with chronic apical periodontitis, and 30 and 90 days after treatment, and compared to those obtained from healthy control patients. Results: It was found that, on recruitment, the patients with chronic apical periodontitis exhibited significantly higher levels of oxidative stress than control patients, as determined by the d-ROMs and BAP tests. Furthermore, the d-ROMs test values were shown to decrease and the BAP test values to increase over time in patients with chronic apical periodontitis following endodontic therapy. As the levels of oxidative stress in these patients tended to reduce and return to normal by 90 days following treatment. Conclusions: This study has demonstrated a positive association between chronic apical periodontitis and oxidative stress. Subjects affected by chronic

Outdoor occupational environments and heat stress in IRAN.

PubMed

Heidari, Hamidreza; Golbabaei, Farideh; Shamsipour, Aliakbar; Rahimi Forushani, Abbas; Gaeini, Abbasali

2015-01-01

The present study aimed at demonstrating the heat stress situation (distribution and intensity) based on a standard and common heat stress index, Wet Bulb Globe Temperature (WBGT), during hot seasons and interpret the obtained results considering global warming and rising temperature in different parts of the country based on climate changes studied in Iran. Heat stress assessment was done using WBGT index. Environmental parameters were measured simultaneously in the early, middle and end of shift work. The personal parameters including cloth thermal insulation and metabolic rate of 242 participants from 9 climatic categories were recorded for estimating effective WBGT (measured WBGT plus cloth adjustment factor as well as metabolic rate effect). The values of the indicator were categorized in the statistical software media and then linked to the climatic zoning of the data in the GIS information layers, in which, WBGT values relating to selected stations were given generalization to similar climatic regionalization. The obtained results showed that in the summer about 60 % and more than 75 % of the measurements relating to 12 pm and 3 pm, respectively, were in heat stress situations (i.e. the average amount of heat stress index was higher than 28 °C). These values were found to be about 20-25 % in the spring. Moreover, only in the early hours of shift work in spring could safe conditions be seen throughout the country. This situation gradually decreased in the middle of the day hours and was replaced by the warning status and stress. And finally, in the final hours of shift work thermal stresses reached their peaks. These conditions for the summer were worse. Regarding several studies related to climate change in Iran and the results of present study, heat stress, especially in the central and southern parts of Iran, can be exacerbated in the decades to come if climate change and rising temperature occurs. Therefore, paying attention to this critical issue

Stressors, Appraisal of Stressors, Experienced Stress and Cardiac Response: A Real-Time, Real-Life Investigation of Work Stress in Nurses.

PubMed

Johnston, Derek; Bell, Cheryl; Jones, Martyn; Farquharson, Barbara; Allan, Julia; Schofield, Patricia; Ricketts, Ian; Johnston, Marie

2016-04-01

Stress in health care professionals may reflect both the work and appraisal of work and impacts on the individuals, their patients, colleagues and managers. The purpose of the present study is to examine physiological and psychological effects of stressors (tasks) and theory-based perceptions of work stressors within and between nurses in real time. During two work shifts, 100 nurses rated experienced stress, affect, fatigue, theory-based measures of work stress and nursing tasks on electronic diaries every 90 min, whereas heart rate and activity were measured continuously. Heart rate was associated with both demand and effort. Experienced stress was related to demand, control, effort and reward. Effort and reward interacted as predicted (but only within people). Results were unchanged when allowance was made for work tasks. Real-time appraisals were more important than actual tasks in predicting both psychological and physiological correlates of stress. At times when effort was high, perceived reward reduced stress.

Does translocation influence physiological stress in the desert tortoise?

USGS Publications Warehouse

Drake, K.K.; Nussear, K.E.; Esque, T.C.; Barber, A.M.; Vittum, K.M.; Medica, P.A.; Tracy, C.R.; Hunter, K.W.

2012-01-01

Wildlife translocation is increasingly used to mitigate disturbances to animals or habitat due to human activities, yet little is known about the extent to which translocating animals causes stress. To understand the relationship between physiological stress and translocation, we conducted a multiyear study (2007–2009) using a population of desert tortoises (Gopherus agassizii) near Fort Irwin, California. Blood samples were collected from adult tortoises in three treatment groups (resident, translocated and control) for 1 year prior to and 2 years after translocation. Samples were analyzed by radioimmunoassay for plasma total corticosterone (CORT), a glucocorticoid hormone commonly associated with stress responses in reptiles. CORT values were analyzed in relation to potential covariates (animal sex, date, behavior, treatment, handling time, air temperature, home-range size, precipitation and annual plant production) among seasons and years. CORT values in males were higher than in females, and values for both varied monthly throughout the activity season and among years. Year and sex were strong predictors of CORT, and translocation explained little in terms of CORT. Based on these results, we conclude that translocation does not elicit a physiological stress response in desert tortoises.