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Sample records for age hardening behavior

  1. Hydrogen effects on the age hardening behavior of 2024 aluminum

    NASA Technical Reports Server (NTRS)

    Wagner, J. A.; Louthan, M. R., Jr.; Sisson, R. D., Jr.

    1986-01-01

    It has been found that the fatigue crack growth rate in aluminum alloys increases significantly in the presence of moisture. This phenomenon along with a moisture effect observed in another context has been attributed to 'embrittlement' of the aluminum by absorbed hydrogen generated by the reaction of moisture with freshly exposed aluminum. A description is given of a number of age hardening experiments involving 2024 aluminum. These experiments show that a mechanism related to the segregation of absorbed hydrogen to the coherent theta-double-prime interfaces may account for the observed reduction in fatigue life. It is pointed out that this segregation promotes a loss of coherency in the hydrogen rich region at a fatigue crack tip. Subsequently, the loss of coherency causes local softening and reduces fatigue life.

  2. Microstructural evolution and the variation of tensile behavior after aging heat treatment of precipitation hardened martensitic steel

    SciTech Connect

    Shin, Jong-Ho; Jeong, JaeSuk; Lee, Jong-Wook

    2015-01-15

    The effects of aging temperature on the microstructural evolution and the tensile behavior of precipitation hardened martensitic steel were investigated. Microscopic analysis using transmission electron microscope (TEM) was combined with the microstructural analysis using the synchrotron X-ray diffraction (XRD) to characterize the microstructural evolution with aging temperature. Peak hardness was obtained by precipitation of the Ni{sub 3}Al ordered phase. After aging at temperature range from 420 to 590 °C, spherical Ni{sub 3}Al precipitates and ellipsoidal M{sub 23}C{sub 6} carbides were observed within laths and at lath boundaries, respectively. Strain hardening behavior was analyzed with Ludwik equation. It is observed that the plastic strain regimes can be divided into two different stages by a rapid increase in strain hardening followed by a comparatively lower increase. At the first strain hardening stage, the aged specimen exhibited higher strain hardening exponent than the as-quenched specimen, and the exponent in the aged specimen was not changed considerably with increasing aging temperature. It is revealed that the strain hardening exponents at the first and the second stages were associated with the Ni{sub 3}Al precipitates and the domain size representing the coherent scattering area, respectively. - Highlights: • All of aged specimen exhibited higher strain hardening exponent than the as-quenched specimen at the first stage. • The value of strain hardening exponent in the aged specimen was nearly constant with aging temperature. • Ni{sub 3}Al precipitation dominantly influenced to the increase of strain hardening exponent at the first strain hardening stage. • Domain size was associated with strain hardening exponent at the second strain hardening stage.

  3. Age hardening characteristics and mechanical behavior of Al-Cu-Li-Zr-In alloys

    NASA Technical Reports Server (NTRS)

    Wagner, John A.

    1989-01-01

    An investigation was conducted to determine the age-hardening response and cryogenic mechanical properties of superplastic Al-Cu-Li-Zr-In alloys. Two alloys with compositions Al-2.65Cu-2.17Li-O.13Zr (baseline) and Al-2.60Cu-2.34Li-0.16Zr-0.17In were scaled-up from 30 lb permanent mold ingots to 350 lb DC (direct chill) ingots and thermomechanically processed to 3.2 mm thick sheet. The microstructure of material which contained the indium addition was partially recrystallized compared to the baseline suggesting that indium may influence recrystallization behavior. The indium-modified alloy exhibited superior hardness and strength compared to the baseline alloy when solution-heat-treated at 555 C and aged at 160 C or 190 C. For each alloy, strength increased and toughness was unchanged or decreased when tested at - 185 C compared to ambient temperature. By using optimized heat treatments, the indium-modified alloy exhibited strength levels approaching those of the baseline alloy without deformation prior to aging. The increase in strength of these alloys in the T6 condition make them particularly attractive for superplastic forming applications where post-SPF parts cannot be cold deformed to increase strength.

  4. Influence of Thermal Aging on the Microstructure and Mechanical Behavior of Dual Phase Precipitation Hardened Powder Metallurgy Stainless Steels

    NASA Astrophysics Data System (ADS)

    Stewart, Jennifer

    2011-12-01

    Increasing demand for high strength powder metallurgy (PM) steels has resulted in the development of dual phase PM steels. In this work, the effects of thermal aging on the microstructure and mechanical behavior of dual phase precipitation hardened powder metallurgy (PM) stainless steels of varying ferrite-martensite content were examined. Quantitative analyses of the inherent porosity and phase fractions were conducted on the steels and no significant differences were noted with respect to aging temperature. Tensile strength, yield strength, and elongation to fracture all increased with increasing aging temperature reaching maxima at 538°C in most cases. Increased strength and decreased ductility were observed in steels of higher martensite content. Nanoindentation of the individual microconstituents was employed to obtain a fundamental understanding of the strengthening contributions. Both the ferrite and martensite hardness values increased with aging temperature and exhibited similar maxima to the bulk tensile properties. Due to the complex non-uniform stresses and strains associated with conventional nanoindentation, micropillar compression has become an attractive method to probe local mechanical behavior while limiting strain gradients and contributions from surrounding features. In this study, micropillars of ferrite and martensite were fabricated by focused ion beam (FIB) milling of dual phase precipitation hardened powder metallurgy (PM) stainless steels. Compression testing was conducted using a nanoindenter equipped with a flat punch indenter. The stress-strain curves of the individual microconstituents were calculated from the load-displacement curves less the extraneous displacements of the system. Using a rule of mixtures approach in conjunction with porosity corrections, the mechanical properties of ferrite and martensite were combined for comparison to tensile tests of the bulk material, and reasonable agreement was found for the ultimate tensile

  5. The Effect of Microstructural Evolution on Hardening Behavior of 2205 Stainless Steel in Long-Term Aging at 500 °C

    NASA Astrophysics Data System (ADS)

    Shi, Shukun; Ma, Guodong; Guo, Bo; Fang, Kuanjun; Wang, Jun

    2014-06-01

    The effect of microstructural evolution on hardening behavior of 2205 stainless steel in long-term aging at 500 °C was studied by optical microscope, scanning electron microscope, and transmission electron microscope. The results showed that the hardness of ferrite phase in matrix steadily increased with the aging time at the first stage of 4 months, presented a peak of hardness at about 5 months, and showed a downward trend for the aging time from 6 to 8 months, while the hardness of the austenitic phase remained constant. Analysis showed that the iron-rich α phase and the Cr-rich α' phase generated by spinodal decomposition, Cr2N precipitations, and Fe2Mn (R-phase) were the main reasons for the generation of peak in hardness of ferrite phase. Further studies showed that some dislocation structure (changing with the aging time) in δ-ferrite of matrix is related to the microstructural evolution.

  6. Comparative study of structure formation and mechanical behavior of age-hardened Ti–Nb–Zr and Ti–Nb–Ta shape memory alloys

    SciTech Connect

    Inaekyan, K.; Brailovski, V.; Prokoshkin, S.; Pushin, V.; Dubinskiy, S.; Sheremetyev, V.

    2015-05-15

    This work sets out to study the peculiar effects of aging treatment on the structure and mechanical behavior of cold-rolled and annealed biomedical Ti–21.8Nb–6.0Zr (TNZ) and Ti–19.7Nb–5.8Ta (TNT) (at.%) shape memory alloys by means of transmission electron microscopy, X-ray diffractometry, functional fatigue and thermomechanical testing techniques. Dissimilar effects of aging treatment on the mechanical behavior of Zr- and Ta-doped alloys are explained by the differences in the ω-phase formation rate, precipitate size, fraction and distribution, and by their effect on the alloys' critical stresses and transformation temperatures. Even short-time aging of the TNZ alloy leads to its drastic embrittlement caused by “overaging”. On the contrary, during aging of the TNT alloy, formation of finely dispersed ω-phase precipitates is gradual and controllable, which makes it possible to finely adjust the TNT alloy functional properties using precipitation hardening mechanisms. To create in this alloy nanosubgrained dislocation substructure containing highly-dispersed coherent nanosized ω-phase precipitates, the following optimum thermomechanical treatment is recommended: cold rolling (true strain 0.37), followed by post-deformation annealing (600 °C, 15–30 min) and age-hardening (300 °C, 30 min) thermal treatments. It is shown that in TNT alloy, pre-transition diffraction effects (diffuse reflections) can “mask” the β-phase substructure and morphology of secondary phases. - Highlights: • TNZ alloy is characterized by much higher ω-phase precipitation rate than TNT alloy. • Difference in precipitation rates is linked to the difference in Zr and Ta diffusion mobility. • Aging of nanosubgrained TNZ alloy worsens its properties irrespective of the aging time. • Aging time of nanosubgrained TNT alloy can be optimized to improve its properties.

  7. Weldable, age hardenable, austenitic stainless steel

    DOEpatents

    Brooks, J.A.; Krenzer, R.W.

    1975-07-22

    An age hardenable, austenitic stainless steel having superior weldability properties as well as resistance to degradation of properties in a hydrogen atmosphere is described. It has a composition of from about 24.0 to about 34.0 weight percent (w/o) nickel, from about 13.5 to about 16.0 w/o chromium, from about 1.9 to about 2.3 w/o titanium, from about 1.0 to about 1.5 w/ o molybdenum, from about 0.01 to about 0.05 w/o carbon, from about 0 to about 0.25 w/o manganese, from about 0 to about 0.01 w/o phosphorous and preferably about 0.005 w/o maximum, from about 0 to about 0.010 w/o sulfur and preferably about 0.005 w/o maximum, from about 0 to about 0.25 w/o silicon, from about 0.1 to about 0.35 w/o aluminum, from about 0.10 to about 0.50 w/o vanadium, from about 0 to about 0.0015 w/o boron, and the balance essentially iron. (auth)

  8. Effect of reinforcing particle type on morphology and age-hardening behavior of Al–4.5 wt.% Cu based nanocomposites synthesized through mechanical milling

    SciTech Connect

    Mostaed, A.; Saghafian, H.; Mostaed, E.; Shokuhfar, A.; Rezaie, H.R.

    2013-02-15

    The effects of reinforcing particle type (SiC and TiC) on morphology and precipitation hardening behavior of Al–4.5%Cu based nanocomposites synthesized via mechanical milling were investigated in the current work. In order to study the microstructure and morphology of mechanically milled powder, X-ray diffraction technique, scanning electron microscopy and high resolution transmission electron microscopy were utilized. Results revealed that at the early stages of mechanical milling, when reinforcing particles are polycrystal, the alloying process is enhanced more in the case of using the TiC particles as reinforcement. But, at the final stages of mechanical milling, when reinforcing particles are single crystal, the alloying process is enhanced more in the case of using the SiC ones. Transmission electron microscopy results demonstrated that Al–4.5 wt.%Cu based nanocomposite powders were synthesized and confirmed that the mutual diffusion of aluminum and copper occurs through the interfacial plane of (200). The hardness results showed that not only does introducing 4 vol.% of reinforcing particles (SiC or TiC) considerably decrease the porosity of the bulk composite samples, but also it approximately doubles the hardness of Al–4.5 wt.%Cu alloy (53.4 HB). Finally, apart from TEM and scanning electron microscopy observation which are localized, a decline in hardness in the TiC and SiC contained samples, respectively, after 1.5 and 2 h aging time at 473 K proves the fact that the size of SiC particles is smaller than the size of the TiC ones. - Highlights: ► HRTEM results show mutual diffusion of Al and Cu occurs through the (200) planes. ► TiC particles enhance alloying process more than the SiC ones at the early stages of MM. ► SiC particles enhance alloying process more than the TiC ones at the final stages of MM.

  9. Continuous Hardening During Isothermal Aging at 723 K (450 °C) of a Precipitation Hardening Stainless Steel

    NASA Astrophysics Data System (ADS)

    Celada-Casero, Carola; Chao, Jesús; Urones-Garrote, Esteban; San Martin, David

    2016-11-01

    The isothermal aging behavior of a cold-rolled precipitation hardening stainless steel has been studied at 723 K (450 °C) for holding times up to 72 hours. The precipitation hardening has been investigated using microhardness Vickers (Hv), thermoelectric power (TEP) measurements, and tensile testing. Microhardness compared to TEP measurements is more sensitive to detect the initial stages of aging. Two precipitation regimes have been observed: the first one related to the formation of Cu-clusters for aging times below 1 hour and a second one associated with formation of Ni-rich precipitates. The results show that the material exhibits an outstanding continuous age strengthening response over the aging time investigated, reaching a hardness of 710 ± 4 HV1 and an ultimate tensile strength ( σ UTS) of 2.65 ± 0.02 GPa after 72 hours. Engineering stress-plastic strain curves reveal that the strength increases and the ductility decreases as the aging time increases. However, after prolonged holding times (24-72 hours) and, although small, a rise in both the strength and the total elongation is observed. The precipitation kinetics can be well predicted over the entire range of aging times by the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. Finally, a reliable linear hardness-yield strength correlation has been found, which enables a rapid evaluation of the strength from bulk hardness measurements.

  10. Continuous Hardening During Isothermal Aging at 723 K (450 °C) of a Precipitation Hardening Stainless Steel

    NASA Astrophysics Data System (ADS)

    Celada-Casero, Carola; Chao, Jesús; Urones-Garrote, Esteban; San Martin, David

    2016-06-01

    The isothermal aging behavior of a cold-rolled precipitation hardening stainless steel has been studied at 723 K (450 °C) for holding times up to 72 hours. The precipitation hardening has been investigated using microhardness Vickers (Hv), thermoelectric power (TEP) measurements, and tensile testing. Microhardness compared to TEP measurements is more sensitive to detect the initial stages of aging. Two precipitation regimes have been observed: the first one related to the formation of Cu-clusters for aging times below 1 hour and a second one associated with formation of Ni-rich precipitates. The results show that the material exhibits an outstanding continuous age strengthening response over the aging time investigated, reaching a hardness of 710 ± 4 HV1 and an ultimate tensile strength (σ UTS) of 2.65 ± 0.02 GPa after 72 hours. Engineering stress-plastic strain curves reveal that the strength increases and the ductility decreases as the aging time increases. However, after prolonged holding times (24-72 hours) and, although small, a rise in both the strength and the total elongation is observed. The precipitation kinetics can be well predicted over the entire range of aging times by the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. Finally, a reliable linear hardness-yield strength correlation has been found, which enables a rapid evaluation of the strength from bulk hardness measurements.

  11. Age hardening of 6061/alumina-silica fiber composite

    SciTech Connect

    Khangaonkar, P.R.; Shamsul, J.B.; Azmi, R.

    1994-12-31

    Continuous alumina-silica fiber (Altex of Sumitomo) which yields high performance composites with some aluminium alloys was tried for squeeze cast 6061 based composites with volume fractions of 0.5 and 0.32, and the matrix microhardness and resistivity changes during age hardening were studied. The matrix in the composites hardened much more than the unreinforced alloy. Microhardness increases of up to 70 VPN above the solution treated condition at various aging temperatures were observed. The resistivity variation indicated an appreciable state of internal stress which continued to persist even when hardness fell by overaging. Energy dispersive X-ray analysis indicated that the regions close to the fibers had a higher silicon content than the matrix, and amorphous silica in the fiber may have a role in the formation of an enriched layer which may help the bonding and strength in the composite.

  12. Description of full-range strain hardening behavior of steels.

    PubMed

    Li, Tao; Zheng, Jinyang; Chen, Zhiwei

    2016-01-01

    Mathematical expression describing plastic behavior of steels allows the execution of parametric studies for many purposes. Various formulas have been developed to characterize stress strain curves of steels. However, most of those formulas failed to describe accurately the strain hardening behavior of steels in the full range which shows various distinct stages. For this purpose, a new formula is developed based on the well-known Ramberg-Osgood formula to describe the full range strain hardening behavior of steels. Test results of all the six types of steels show a three-stage strain hardening behavior. The proposed formula can describe such behavior accurately in the full range using a single expression. The parameters of the formula can be obtained directly and easily through linear regression analysis. Excellent agreements with the test data are observed for all the steels tested. Furthermore, other formulas such as Ludwigson formula, Gardner formula, UGent formula are also applied for comparison. Finally, the proposed formula is considered to have wide suitability and high accuracy for all the steels tested.

  13. Description of full-range strain hardening behavior of steels.

    PubMed

    Li, Tao; Zheng, Jinyang; Chen, Zhiwei

    2016-01-01

    Mathematical expression describing plastic behavior of steels allows the execution of parametric studies for many purposes. Various formulas have been developed to characterize stress strain curves of steels. However, most of those formulas failed to describe accurately the strain hardening behavior of steels in the full range which shows various distinct stages. For this purpose, a new formula is developed based on the well-known Ramberg-Osgood formula to describe the full range strain hardening behavior of steels. Test results of all the six types of steels show a three-stage strain hardening behavior. The proposed formula can describe such behavior accurately in the full range using a single expression. The parameters of the formula can be obtained directly and easily through linear regression analysis. Excellent agreements with the test data are observed for all the steels tested. Furthermore, other formulas such as Ludwigson formula, Gardner formula, UGent formula are also applied for comparison. Finally, the proposed formula is considered to have wide suitability and high accuracy for all the steels tested. PMID:27563511

  14. Elastic constant versus temperature behavior of three hardened maraging steels

    NASA Technical Reports Server (NTRS)

    Ledbetter, H. M.; Austin, M. W.

    1985-01-01

    Elastic constants of three maraging steels were determined by measuring ultrasonic velocities. Annealed steels show slightly lower bulk moduli and considerably lower shear moduli than hardened steels. All the elastic constants (Young's modulus, shear modulus, bulk modulus and Poisson's ratio) show regular temperature behavior between 76 and 400 K. Young's modulus and the shear modulus increase with increasing yield strength, but the bulk modulus and Poisson's ratio are relatively unchanged. Elastic anisotropy is quite small.

  15. Microstructure, Mechanical Properties, and Age-Hardening Behavior of an Al-Si-Fe-Mn-Cu-Mg Alloy Produced by Spray Deposition

    NASA Astrophysics Data System (ADS)

    Feng, Wang; Jishan, Zhang; Baiqing, Xiong; Yongan, Zhang

    2011-02-01

    It has been recognized generally that the spray-deposited process is an innovative technique of rapid solidification. In this paper, Al-20Si-5Fe-3Mn-3Cu-1Mg alloy was synthesized by the spray atomization and deposition technique. The microstructure and mechanical properties of the spray-deposited alloy were studied using x-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), and tensile tests. It is observed that the microstructure of spray-deposited Al-20Si-5Fe-3Mn-3Cu-1Mg alloy is composed of the α-Al,Si and the particle-like Al15(FeMn)3Si2 compounds. The aging process of the alloy was investigated by microhardness measurement, differential scanning calorimetry analysis, and TEM observations. The results indicate that the two types of precipitates, S-Al2CuMg and σ-Al5Cu6Mg2 precipitate from matrix and improve the tensile strength of the alloy efficiently at both the ambient and elevated temperatures (300 °C).

  16. Strain Hardening Behavior of Dual-Phase Steels

    NASA Astrophysics Data System (ADS)

    Colla, V.; de Sanctis, M.; Dimatteo, A.; Lovicu, G.; Solina, A.; Valentini, R.

    2009-11-01

    A detailed qualitative and quantitative examination of the microstructure and mechanical properties of three different classes of DP600 and DP450 dual-phase (DP) steels was carried out. The tested DP steels are characterized by different alloying elements: aluminum, boron, and phosphorus. Among them, aluminum DP steels showed the lowest percentages of hard phases, while phosphorus DP steels exhibited the highest resistance values. The Hollomon, Pickering, Crussard-Jaoul (CJ), and Bergstrom models were used to reproduce the strain hardening behavior of DP steels. Relationships that correlate the fitting parameters with the chemical composition and the thermal cycle parameters were found, and the predictive abilities of different models were evaluated. The Pickering equation, among the tested models, is the best one in the reproduction of the experimental stress-strain data.

  17. Effects of Ce additions on the age hardening response of Mg–Zn alloys

    SciTech Connect

    Langelier, Brian Esmaeili, Shahrzad

    2015-03-15

    The effects of Ce additions on the precipitation hardening behaviour of Mg–Zn are examined for a series of alloys, with Ce additions at both alloying and microalloying levels. The alloys are artificially aged, and studied using hardness measurement and X-ray diffraction, as well as optical and transmission electron microscopy. It is found that the age-hardening effect is driven by the formation of fine precipitates, the number density of which is related to the Zn content of the alloy. Conversely, the Ce content is found to slightly reduce hardening. When the alloy content of Ce is high, large secondary phase particles containing both Ce and Zn are present, and remain stable during solutionizing. These particles effectively reduce the amount of Zn available as solute for precipitation, and thereby reduce hardening. Combining hardness results with thermodynamic analysis of alloy solute levels also suggests that Ce can have a negative effect on hardening when present as solutes at the onset of ageing. This effect is confirmed by designing a pre-ageing heat treatment to preferentially remove Ce solutes, which is found to restore the hardening capability of an Mg–Zn–Ce alloy to the level of the Ce-free alloy. - Highlights: • The effects of Ce additions on precipitation in Mg–Zn alloys are examined. • Additions of Ce to Mg–Zn slightly reduce the age-hardening response. • Ce-rich secondary phase particles deplete the matrix of Zn solute. • Hardening is also decreased when Ce is present in solution. • Pre-ageing to preferentially precipitate out Ce restores hardening capabilities.

  18. Distinct Hardening Behavior of Ultrafine-Grained Al-Zn-Mg-Cu Alloy

    NASA Astrophysics Data System (ADS)

    Ma, Kaka; Smith, Thale; Hu, Tao; Topping, Troy D.; Lavernia, Enrique J.; Schoenung, Julie M.

    2014-10-01

    The age-hardening response for ultrafine-grained, powder-metallurgy-consolidated aluminum 7091 was investigated for the first time. Peak hardening occurred after aging at 353 K (80 °C) for only 4 hours; further aging for up to 26 hours resulted in only slight fluctuations in hardness values. After the 4-hour aging, the precipitate population consists of a high density of nanoscale GP zones (diameter ~3 nm) and nanoscale η' phase (<30 nm); η phase is not present.

  19. Phase decomposition in an Fe-40 at.% Cr alloy after isothermal aging and its effect on hardening

    SciTech Connect

    Lopez-Hirata, Victor M. Soriano-Vargas, Orlando; Rosales-Dorantes, Hector J.; Saucedo Munoz, Maribel L.

    2011-08-15

    The phase decomposition process of an Fe-40 at.% Cr alloy was studied after isothermal aging at 475 and 500 deg. C using a high-resolution transmission electron microscope, as well as hardness measurements. High-resolution transmission electron microscope observations showed that the hardening behavior is associated with the formation of the nanometric coherent decomposed Cr-rich and Fe-rich phases with irregular shape and interconnected as expected for a spinodally-decomposed alloy. As the aging progressed, coherent rounded Cr-rich phase precipitates were observed in the Fe-rich phase matrix. The coarsening process of the Cr-rich phase was observed for aging times up to 750 h. Nevertheless, no decrease in hardness with time was observed because of the nanometric size of the Cr-rich phase, less than 10 nm. Aging hardening was higher at 500 deg. C because of the higher decomposition kinetics. - Research Highlights: {yields} Spinodally-decomposed phases showed an interconnected and irregular shape in aged Fe-Cr alloy. {yields} Further aging promoted the formation of nanometric coherent rounded Cr-rich precipitates. {yields} Nanometric Cr-rich phases are responsible for the age hardening. {yields} Coarsening process of these nanometric Cr-rich precipitates caused no decrease in hardness.

  20. Precipitation hardening and microstructure evolution of the Ti-7Nb-10Mo alloy during aging.

    PubMed

    Yi, Ruowei; Liu, Huiqun; Yi, Danqing; Wan, Weifeng; Wang, Bin; Jiang, Yong; Yang, Qi; Wang, Dingchun; Gao, Qi; Xu, Yanfei; Tang, Qian

    2016-06-01

    A biomedical β titanium alloy (Ti-7Nb-10Mo) was designed and prepared by vacuum arc self-consumable melting. The ingot was forged and rolled to plates, followed by quenching and aging. Age-hardening behavior, microstructure evolution and its influence on mechanical properties of the alloy during aging were investigated, using X-ray diffraction, transmission electron microscopy, tensile and hardness measurements. The electrochemical behavior of the alloy was investigated in Ringer's solution. The microstructure of solution-treated (ST) alloy consists of the supersaturated solid solution β phase and the ωath formed during athermal process. The ST alloy exhibits Young's modulus of 80 GPa, tensile strength of 774 MPa and elongation of 20%. The precipitation sequences during isothermal aging at different temperatures were determined as β+ωath→β+ωiso (144 h) at Taging=350-400 °C, β+ωath→β+ωiso+α→β+α at Taging=500°C, and β+ωath→β+α at Taging=600-650 °C, where ωiso forms during isothermal process. The mechanical properties of the alloy can be tailored easily through controlling the phase transition during aging. Comparing with the conventional Ti-6Al-4V alloy, the Ti-7Nb-10Mo alloy is more resistant to corrosion in Ringer's solution. Results show that the Ti-7Nb-10Mo alloy is promising for biomedical applications. PMID:27040253

  1. Precipitation hardening and microstructure evolution of the Ti-7Nb-10Mo alloy during aging.

    PubMed

    Yi, Ruowei; Liu, Huiqun; Yi, Danqing; Wan, Weifeng; Wang, Bin; Jiang, Yong; Yang, Qi; Wang, Dingchun; Gao, Qi; Xu, Yanfei; Tang, Qian

    2016-06-01

    A biomedical β titanium alloy (Ti-7Nb-10Mo) was designed and prepared by vacuum arc self-consumable melting. The ingot was forged and rolled to plates, followed by quenching and aging. Age-hardening behavior, microstructure evolution and its influence on mechanical properties of the alloy during aging were investigated, using X-ray diffraction, transmission electron microscopy, tensile and hardness measurements. The electrochemical behavior of the alloy was investigated in Ringer's solution. The microstructure of solution-treated (ST) alloy consists of the supersaturated solid solution β phase and the ωath formed during athermal process. The ST alloy exhibits Young's modulus of 80 GPa, tensile strength of 774 MPa and elongation of 20%. The precipitation sequences during isothermal aging at different temperatures were determined as β+ωath→β+ωiso (144 h) at Taging=350-400 °C, β+ωath→β+ωiso+α→β+α at Taging=500°C, and β+ωath→β+α at Taging=600-650 °C, where ωiso forms during isothermal process. The mechanical properties of the alloy can be tailored easily through controlling the phase transition during aging. Comparing with the conventional Ti-6Al-4V alloy, the Ti-7Nb-10Mo alloy is more resistant to corrosion in Ringer's solution. Results show that the Ti-7Nb-10Mo alloy is promising for biomedical applications.

  2. Precipitation Reactions in Age-Hardenable Alloys During Laser Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Jägle, Eric A.; Sheng, Zhendong; Wu, Liang; Lu, Lin; Risse, Jeroen; Weisheit, Andreas; Raabe, Dierk

    2016-03-01

    We describe and study the thermal profiles experienced by various age-hardenable alloys during laser additive manufacturing (LAM), employing two different manufacturing techniques: selective laser melting and laser metal deposition. Using scanning electron microscopy and atom probe tomography, we reveal at which stages during the manufacturing process desired and undesired precipitation reactions can occur in age-hardenable alloys. Using examples from a maraging steel, a nickel-base superalloy and a scandium-containing aluminium alloy, we demonstrate that precipitation can already occur during the production of the powders used as starting material, during the deposition of material (i.e. during solidification and subsequent cooling), during the intrinsic heat treatment effected by LAM (i.e. in the heat affected zones) and, naturally, during an ageing post-heat treatment. These examples demonstrate the importance of understanding and controlling the thermal profile during the entire additive manufacturing cycle of age-hardenable materials including powder synthesis.

  3. Quantification of age hardening in maraging steels and an Ni-base superalloy

    SciTech Connect

    Sha, W.

    2000-02-01

    Age hardening process in metallic alloys due to precipitation can be quantified using phase transformation theories. Two ageing stages are of particular interest, for both theory and practice. The early stage of precipitation hardening is under the description of the Johnson-Mehl-Avrami equation. Wilson has recently provided a detailed theoretical analysis for early stages of ageing. Wilson successfully used equations in the quantification of early and over-ageing stages of hardening in an Fe-12Ni-6Mn maraging-type alloy. In the present work, these were applied to further alloys. All the hardness data were taken from published literature. Original references should be consulted for details of materials, testing and characterization.

  4. Age Hardening Kinetics in 7xxx Type (Al-Mg-Zn) Alloys

    SciTech Connect

    Vevecka-Priftaj, A.; Lamani, E.; Fjerdingen, J.; Langsrud, Y.; Gjoennes, J.; Hansen, V.

    2007-04-23

    Age hardening in industrial 7xxx alloys at the temperature 100 deg. and 150 deg. C up to 144 hrs, after solid solution treatments at 450 deg. and 550 deg. C, has been followed by measurements of Vickers hardness, scanning and transmission electron microscopy. The influence of silicon on phase and kinetic of age hardening zones and precipitates has been studied. High iron and silicon content increase the number of primary particle in the alloy. Size distribution of {eta}'-precipitates has been determined.

  5. Modifications of the Response of Materials to Shock Loading by Age Hardening

    NASA Astrophysics Data System (ADS)

    Millett, Jeremy C. F.

    2015-10-01

    The shock response of two age-hardened alloys, aluminum 6061 and copper-2 wt pct beryllium (CuBe), has been investigated in terms of their microstructual state; either solution treated or age hardened. While age hardening induces large increases in strength at quasi-static strain rates, age hardening does not produce the same magnitude of strength increase during shock loading. Examination of the shocked microstructures (of 6061) indicates that the presence of a fine distribution of precipitates throughout the microstructure hinders the motion and generation of dislocations and hence reduces the strain-rate sensitivity of the aged material, thus allowing the properties of the solution-treated state to approach those of the aged. It has also been observed that the shear strength of solution-treated CuBe is near identical to that of pure copper. It is suggested that this is the result of two competing processes; large lattice strains as beryllium substitutes onto the copper lattice inducing a high degree of solution strengthening acting against a reduction in shear strength caused by twinning in the alloy.

  6. Structural influences on the work hardening behavior of aluminum

    SciTech Connect

    Chu, D.

    1994-12-01

    Effects of various grain and subgrain morphologies on low temperature work hardening of pure Al is studied using tensile tests. Plotting the work hardening rate as a function of true stress, the work hardening is separable into two distinct regimes. Both regimes are approximated by a line {Theta} = {Theta}{sub 0} {minus} K{sub 2}{sigma}, where {Theta}{sub 0} is theoretical work hardening rate at zero stress and K{sub 2} is related to dynamic recovery rate. The first or early deformation regime exhibits greater values of {Theta}{sub 0} and K{sub 2} and can extend up to the first 10% strain of tensile deformation. This early deformation regime is contingent on the existence of a pre-existent dislocation substructure from previous straining. The {Theta}{sub 0} and K{sub 2} associated with the early deformation regime are dependent on the strength and orientation of the pre-existent dislocation substructure relative to the new strain path. At high enough temperatures, this pre-existent dislocation substructure is annealed out, resulting in the near elimination of the early deformation regime. In comparison, the latter regime is dominated by the initial grain and/or subgrain morphology and exhibit lower values of {Theta}{sub 0} and K{sub 2}. The actual value of K{sub 2} in the latter regime is strongly dependent on the existence of a subgrain morphology. Recrystallized or well-annealed microstructures exhibit greater values of K{sub 2} than microstructures that remain partially or fully unrecrystallized. The higher K{sub 2} value is indicative of a more rapid dynamic recovery rate and a greater degree of strain relaxation. The ability to achieve a more relaxed state produces a low-energy cellular dislocation substructure upon deformation. The introduction of subgrains hinders the evolution of a low-energy dislocation cell network, giving way to a more random distribution of the dislocation density.

  7. YIELD STRENGTH PREDICTION FOR RAPID AGE-HARDENING HEAT TREATMENT OF ALUMINUM ALLOYS

    SciTech Connect

    Yin, Hebi; Sabau, Adrian S; Ludtka, Gerard Michael; Skszek, Timothy; Niu, X

    2013-01-01

    A constitutive model has been developed to predict the yield strength aging curves for aluminum casting alloys during non-isothermal age-hardening processes. The model provides the specific relationship between the process variables and yield strength. Several aging heat treatment scenarios have been investigated using the proposed model, including two-step aging recipes. Two-step aging heat treatments involve a low temperature regime to promote nucleation of secondary phases and a second step at higher temperature for the growth of the secondary phases. The predicted results show that yield strength of approximately 300MPa might be obtained in shorter aging time, of approximately 30 minutes. Thus, better mechanical properties can be obtained by optimizing the time-temperature schedules for the precipitation hardening process of heat treatable aluminum alloys.

  8. Coarsening and Hardening Behaviors of Cu-Rich Precipitates in Super304H Austenitic Steel

    NASA Astrophysics Data System (ADS)

    Ou, Ping; Xing, Hui; Wang, Xuanli; Sun, Jian; Cui, Zhengqiang; Yang, Changshun

    2015-09-01

    The coarsening and hardening behaviors of Cu-rich precipitates in Super304H austenitic steel aged at 923 K, 973 K, and 1023 K (650 °C, 700 °C, and 750 °C), respectively, have been investigated through measuring the particle size by transmission electron microscopy and microhardness. The results showed the Cu-rich precipitates have a cubic-to-cubic crystallographic relationship and coherent interface with the austenitic matrix during long-time aging, and that the coarsening behavior of the Cu-rich particles can be predicted with the help of the Lifshitz-Slyozov-Wagner theory. The activation energy for coarsening of the Cu-rich precipitates was evaluated to be 212 ± 3 kJ/mol. The coarsening of Cu-rich precipitates is controlled mainly by the volume diffusion of copper atoms in the austenitic matrix. The contributions to the maximum microhardness occurring at different aging temperatures from precipitation strengthening range from about 17 to 25 pct. The strengthening of the Cu-rich precipitates arises mainly from the coherency strain and partially from stacking-fault strengthening.

  9. Age hardening and creep resistance of cast Al–Cu alloy modified by praseodymium

    SciTech Connect

    Bai, Zhihao; Qiu, Feng; Wu, Xiaoxue; Liu, Yingying; Jiang, Qichuan

    2013-12-15

    The effects of praseodymium on age hardening behavior and creep resistance of cast Al–Cu alloy were investigated. The results indicated that praseodymium facilitated the formation of the θ′ precipitates during the age process and improved the hardness of the Al–Cu alloy. Besides, praseodymium resulted in the formation of the Al{sub 11}Pr{sub 3} phase in the grain boundaries and among the dendrites of the modified alloy. Because of the good thermal stability of Al{sub 11}Pr{sub 3} phase, it inhibits grain boundary migration and dislocation movement during the creep process, which contributes to the improvement in the creep resistance of the modified alloy at elevated temperatures. - Highlights: • Pr addition enhances the hardness and creep resistance of the Al–Cu alloy. • Pr addition facilitates the formation of the θ′ precipitates. • Pr addition results in the formation of the Al11Pr3 phase in the Al–Cu alloy.

  10. A Critical Assessment of Cyclic Softening and Hardening Behavior in a Near- α Titanium Alloy During Thermomechanical Fatigue

    NASA Astrophysics Data System (ADS)

    Prasad, Kartik; Sarkar, Rajdeep; Rao, K. Bhanu Sankara; Sundararaman, M.

    2016-10-01

    Thermomechanical fatigue behavior of Ti-alloy Timetal 834 has been studied at two temperature intervals viz. 573 K to 723 K (300 °C to 450 °C) and 723 K to 873 K (450 °C to 600 °C) under mechanical strain-controlled cycling. Among the temperatures studied, the alloy exhibited initial cyclic softening followed by cyclic hardening at 723 K (450 °C) in the temperature interval of 573 K to 723 K (300 °C to 450 °C). However, continuous cyclic hardening was observed at 723 K (450 °C) in 723 K to 873 K (450 °C to 600 °C). At 573 K (300 °C) and 873 K (600 °C), cyclic softening was observed in the cyclic stress response curves in both the temperature intervals. The dislocation substructure was observed to be planar in both the modes of TMF loading. Based on TEM microstructures and few unconventional fatigue tests, the observed cyclic hardening is attributed to dynamic strain aging. The reduced fatigue life at 723 K to 873 K (450 °C to 600 °C) under OP-TMF loading was attributed to the combined effect of cyclic hardening (leading to early strain localization and crack initiation), oxidation, and development of tensile mean stresses.

  11. Influence of grain structure and solute composition on the work hardening behavior of aluminium at cryogenic temperatures

    SciTech Connect

    Chu, D.; Morris, J.W. Jr.

    1993-07-01

    An unrecrystallized structure is found to significantly improve the work hardening characteristics by lowering the work hardening rate during early stages of deformation. This is in contrast to a recrystallized structure, which requires a higher work hardening rate to accommodate the greater degree of multiple slip necessary to maintain strain compatibility between the more randomly oriented grains. The stronger texture associated with the unrecrystallized structure allows deformation to occur more efficiently. Addition of magnesium also improves work hardening by increasing overall level of the work hardening rate. The improved characteristics of the work hardening behavior result in a parallel increase in both the strength and ductility at cryogenic temperatures. These findings are positive since they suggest a method by which improvements in the work hardening behavior and subsequent mechanical properties may be obtained through practical modifications of the microstructure and composition.

  12. Experimental insight into the cyclic softening/hardening behavior of austenitic stainless steel using ultrasonic higher harmonics

    NASA Astrophysics Data System (ADS)

    Zhang, Jianfeng; Xuan, Fu-zhen; Xiang, Yanxun; Zhao, Peng

    2014-11-01

    The correlation of cyclic hardening/softening behavior of 304 stainless steel (SS) was investigated using nonlinear ultrasonic wave technique. Results reveal that primary hardening leads to the increase of acoustic nonlinearity, while secondary hardening causes the reverse tendency. This distinct phenomenon is governed by two competitive mechanisms: in the primary-hardening stage, the ascended acoustic nonlinearity is related to the increase of planar dislocation structures. While in the second-hardening stage, the decrease of acoustic nonlinearity is partly caused by the development of cell structures. In addition, the deformation-induced martensitic transformation also contributes to the increase of acoustic nonlinearity under higher stress amplitudes.

  13. Theoretical Study of the Oxidation Behavior of Precipitation Hardening Steel

    SciTech Connect

    Pistofidis, N.; Vourlias, G.; Chrissafis, K.; Psyllaki, P.

    2010-01-21

    The oxidation of precipitation hardening (PH) steels is a rather unexplored area. In the present work an attempt is made is made to estimate the kinetics of a PH steel. For this purpose specimens of the material under examination were isothermally heated at 850, 900 and 950 deg. C for 15 hr. Kinetics was based on TGA results. During heating a thick scale is formed on the substrate surface, which is composed by different oxides. The layer close to the substrate is compact and as a result it impedes corrosion. The mathematical analysis of the collected data shows that the change of the mass of the substrate per unit area versus time is described by a parabolic law.

  14. Age hardening in beryllium-aluminum-silver alloys

    SciTech Connect

    Carter, D.H.; McGeorge, A.C.; Jacobson, L.A.; Stanek, P.W.

    1996-11-01

    Three different alloys of beryllium-aluminum-silver were processed to powder by centrifugal atomization in a helium atmosphere. Alloy compositions were, by weight percent, Be-47.5Al-2.5Ag, Be-47Al-3Ag, and Be-46Al-4Ag. Due to the low solubility of both aluminum and silver in beryllium, the silver was concentrated in the aluminum phase, which separates from the beryllium in the liquid phase. A fine, continuous composite beryllium-aluminum microstructure was formed, which did not significantly change after hot isostatic pressing. Samples of hot isostatically pressed material were solution treated at 550 C for 1 h, followed by a water quench. Aging temperatures were 150, 175, 200, and 225 C for times ranging from half an hour to 65 h. Results indicate that peak hardness was reached in 36--40 h at 175 C and 12--16 h at 200 C aging temperature, relatively independent of alloy composition.

  15. The Strain-Hardening Behavior of TZAV-30 Alloy After Various Heat Treatments

    NASA Astrophysics Data System (ADS)

    Liang, S. X.; Yin, L. X.; Zheng, L. Y.; Ma, M. Z.; Liu, R. P.

    2016-02-01

    The Ti-Zr-Al-V series titanium alloys with excellent mechanical properties and low density exhibit tremendous application potential as structural materials in aviation, automotive, and navigation industries. The strain-hardening behavior of Ti-30Zr-5Al-3V (wt.%, TZAV-30) alloy with various heat treatments is investigated in this study. Experimental results show that strain-hardening behavior of the examined alloy depends on the heat treatment process. The average strain-hardening exponent, n, is approximately 0.061 for WA specimen (825 °C/0.5 h/water quenching + 600 °C/4 h/air cooling), 0.068 for FC (850 °C/0.5 h/furnace cooling), 0.121 for AC (850 °C/0.5 h/air cooling), and 0.412 for WQ (850 °C/0.5 h/water quenching). Analysis of strain-hardening rate versus true strain curves indicates that higher n of AC specimen results from the lower degradation rate of strain-hardening rate with strain, and the ultrahigh n of WQ specimen is attributed to the evident increase in strain-hardening rate at the true strain from 0.04 to 0.06. Phase constitution and microstructural analyses reveal that the n of the examined alloy with α + β phases increases with the increase in the relative content of the retained β phase but is independent of average thickness of α plates. The increase in strain-hardening rate in WQ specimen depends on metastable α″ martensite and martensitic transition induced by tensile stress.

  16. Aging processes in precipitation-hardening composite materials based on a D16 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Chernyshova, T. A.; Kobeleva, L. I.

    2010-09-01

    Aging of composite materials (CMs) based on an aluminum D16 alloy and reinforced by Al3Ti intermetallic inclusions (0-10 vol %) having formed upon an in situ reaction and by SiC particles (0-30 vol %) ≤3 or 28 μm in size is studied. Oxide ceramic nanoparticles (0.1 wt %) are used to modify the structure of the CMs. The structures of the CMs before and after aging are analyzed by optical microscopy and scanning electron microscopy on a microscope equipped with an X-ray energy dispersive spectrometer. The hardness of the CMs is measured. The overall hardening of aged CMs is shown to result from a competition between the hardening effects induced by the formation of Guinier-Preston zones and the precipitation of the high-temperature θ and S phases. These effects are controlled by the dislocation density in the matrix.

  17. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths

    DOE PAGES

    Jiao, Z. B.; Luan, J. H.; Miller, M. K.; Yu, C. Y.; Liu, C. T.

    2016-02-19

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for twomore » interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. Lastly, the co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications.« less

  18. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths.

    PubMed

    Jiao, Z B; Luan, J H; Miller, M K; Yu, C Y; Liu, C T

    2016-02-19

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for two interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. The co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications.

  19. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths

    NASA Astrophysics Data System (ADS)

    Jiao, Z. B.; Luan, J. H.; Miller, M. K.; Yu, C. Y.; Liu, C. T.

    2016-02-01

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for two interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. The co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications.

  20. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths

    PubMed Central

    Jiao, Z. B.; Luan, J. H.; Miller, M. K.; Yu, C. Y.; Liu, C. T.

    2016-01-01

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for two interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. The co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications. PMID:26892834

  1. Identifying Deformation and Strain Hardening Behaviors of Nanoscale Metallic Multilayers Through Nano-wear Testing

    DOE PAGES

    Economy, David Ross; Mara, Nathan A.; Schoeppner, R.; Schultz, Bradley M.; Unocic, Raymond R.; Kennedy, Marian S.

    2016-01-13

    In complex loading conditions (e.g. sliding contact), mechanical properties, such as strain hardening and initial hardness, will dictate the long-term performance of materials systems. With this in mind, the strain hardening behaviors of Cu/Nb nanoscale metallic multilayer systems were examined by performing nanoindentation tests within nanoscratch wear boxes and undeformed, as-deposited regions. Both the architecture and substrate influence were examined by utilizing three different individual layer thicknesses (2, 20, and 100 nm) and two total film thicknesses (1 and 10 μm). After nano-wear deformation, multilayer systems with thinner layers showed less volume loss as measured by laser scanning microscopy. Additionally,more » the hardness of the deformed regions significantly rose with respect to the as-deposited measurements, which further increased with greater wear loads. Strain hardening exponents for multilayers with thinner layers (2 and 20 nm, n ≈ 0.018 and n ≈ 0.022 respectively) were less than was determined for 100 nm systems (n ≈ 0.041). These results suggest that singledislocation based deformation mechanisms observed for the thinner systems limit the extent of achievable strain hardening. This conclusion indicates that impacts of both architecture strengthening and strain hardening must be considered to accurately predict multilayer performance during sliding contact across varying length scales.« less

  2. Identifying Deformation and Strain Hardening Behaviors of Nanoscale Metallic Multilayers Through Nano-wear Testing

    NASA Astrophysics Data System (ADS)

    Economy, D. Ross; Mara, N. A.; Schoeppner, R. L.; Schultz, B. M.; Unocic, R. R.; Kennedy, M. S.

    2016-03-01

    In complex loading conditions ( e.g., sliding contact), mechanical properties, such as strain hardening and initial hardness, will dictate the long-term performance of materials systems. With this in mind, the strain hardening behaviors of Cu/Nb nanoscale metallic multilayer systems were examined by performing nanoindentation tests within nanoscratch wear boxes and undeformed regions (as-deposited). Both the architecture and substrate influence were examined by utilizing three different individual layer thicknesses (2, 20, and 100 nm) and two total film thicknesses (1 and 10 µm). After nano-wear deformation, multilayer systems with thinner layers showed less volume loss as measured by laser scanning microscopy. Additionally, the hardness of the deformed regions significantly rose with respect to the as-deposited measurements, which further increased with greater wear loads. Strain hardening exponents for multilayers with thinner layers (2 and 20 nm, n ≈ 0.018 and n ≈ 0.022, respectively) were less than that determined for 100 nm systems ( n ≈ 0.041). These results suggest that single-dislocation-based deformation mechanisms observed for the thinner systems limit the extent of achievable strain hardening. This conclusion indicates that impacts of both architecture strengthening and strain hardening must be considered to accurately predict multilayer performance during sliding contact across varying length scales.

  3. Effects of alloying on aging and hardening processes of steel with 20% nickel

    NASA Technical Reports Server (NTRS)

    Bogachev, I. N.; Zvigintsev, N. V.; Maslakova, T. M.

    1981-01-01

    Measurements of hardness, thermal emf, and electrical resistance were used to study the effects of Co, Mo, Ti and Al contents on aging and hardening processes in Fe 20%Ni steel. It is shown that the effects of these alloying elements differ substantially. Anomalies which arise in the temperature dependence of physical properties due to the presence of cobalt and molybdenum are reduced by the inclusion of titanium and aluminum (and vice versa).

  4. Deformation behavior in reactor pressure vessel steels as a clue to understanding irradiation hardening.

    SciTech Connect

    DiMelfi, R. J.; Alexander, D. E.; Rehn, L. E.

    1999-10-25

    In this paper, we examine the post-yield true stress vs true strain behavior of irradiated pressure vessel steels and iron-based alloys to reveal differences in strain-hardening behavior associated with different irradiating particles (neutrons and electrons) and different alloy chernky. It is important to understand the effects on mechanical properties caused by displacement producing radiation of nuclear reactor pressure steels. Critical embrittling effects, e.g. increases in the ductile-to-brittle-transition-temperature, are associated with irradiation-induced increases in yield strength. In addition, fatigue-life and loading-rate effects on fracture can be related to the post-irradiation strain-hardening behavior of the steels. All of these properties affect the expected service life of nuclear reactor pressure vessels. We address the characteristics of two general strengthening effects that we believe are relevant to the differing defect cluster characters produced by neutrons and electrons in four different alloys: two pressure vessel steels, A212B and A350, and two binary alloys, Fe-0.28 wt%Cu and Fe-0.74 wt%Ni. Our results show that there are differences in the post-irradiation mechanical behavior for the two kinds of irradiation and that the differences are related both to differences in damage produced and alloy chemistry. We find that while electron and neutron irradiations (at T {le} 60 C) of pressure vessel steels and binary iron-based model alloys produce similar increases in yield strength for the same dose level, they do not result in the same post-yield hardening behavior. For neutron irradiation, the true stress flow curves of the irradiated material can be made to superimpose on that of the unirradiated material, when the former are shifted appropriately along the strain axis. This behavior suggests that neutron irradiation hardening has the same effect as strain hardening for all of the materials analyzed. For electron irradiated steels, the

  5. Effects of age hardening on magnetic and transport properties of Mg-1.3 wt% Ce alloys

    SciTech Connect

    Yamashita, T.; Cavallaro, P.; Kelly, P.M.; Hisa, M.

    1998-05-22

    Magnesium is the lightest structural metal. It has advantages over many other materials in terms of specific strength, machinability and shock absorption. Improvements in magnesium alloy design and more stringent requirements to reduce fuel consumption and air pollution, have recently focused attention on the use of magnesium alloys for automotive components. Here, a Mg-1.3 wt% Ce alloy has been isothermally heat treated at 423 K and the transport and magnetic properties are investigated. This alloy is known to have distinct age hardening behavior and its age hardened microstructure has been studied in detail. The transport properties depend on the early stage of precipitation which is difficult to define by transmission electron microscopy. The scattering sites of electrons are not identical to precipitates, but consist of strain fields induced by the precipitates, solute atoms, dislocations and vacancies. The resistivity was found to increase initially with aging time and then decrease. The highest resistivity was obtained from a specimen aged for 3.6 ks. This aging time is far less than that of 1,800 ks which gives the maximum hardness. On the other hand, magnetic properties correlate with the later stages of the precipitation. In particular, the imaginary part of the magnetic susceptibility is related to macroscopic formation of precipitates. The imaginary part of the magnetic susceptibility of the alloys seems to be generated by eddy current loss. The imaginary part of the magnetic susceptibility increases monotonically with aging time but it may decrease for extensive aging treatments beyond 3,600 ks.

  6. Mechanisms of formation of hardening precipitates and hardening in aging of Al-Li-Cu-Mg model alloys with silver additions

    NASA Astrophysics Data System (ADS)

    Alekseev, A. A.; Zhuravleva, P. L.; Onuchina, M. R.; Klochkova, Yu. Yu.

    2015-11-01

    The mechanisms of the influence of silver additions on the phase transformations that occur in aging are revealed. The contribution of Ω'-phase particles to the deformation stress in Al alloys is estimated. The mechanisms of the effect of low (up to 0.5 wt %) silver additions and the copper content on the structure of the Ω'-phase precipitates in Al alloys are found. According to the proposed model, silver atoms remain immobile during the decomposition of a solid solution and nucleation centers of the Ω' phase form near them in low-temperature aging. Upon hardening aging, fragmented Ω'-phase particles intersect with each other, and the contribution of the intersection regions to the hardening of alloys by Ω'-phase particles is principal.

  7. Mechanical properties evaluations of an age hardenable martensitic steel deformed by equal channel angular pressing.

    PubMed

    Nili-Ahmadabadi, M; Shirazi, H; Iranpour Mobarake, M; Poorganji, B; Hossein Nedjad, S; Furuhara, T

    2010-09-01

    Effect of severe plastic deformation by equal channel angular pressing on the mechanical properties of an age hardenable low carbon martensitic steel was investigated. Equal Channel angular pressing was carried out on the solution-annealed steel up to four passes at room temperature through the route Bc. Aging was carried out at 753 K for 2.4 ks. It was found that after four passes deformation, the microstructure is consist of fine grained high angle grain boundaries and lamellar dislocation cell block. The strength of steel is increased considerably while a increasing in elongation is revealed. PMID:21133170

  8. Inhibition of environmental fatigue crack propagation in age-hardenable aluminum alloys

    NASA Astrophysics Data System (ADS)

    Warner, Jenifer S.

    Age-hardenable aluminum alloys, such as C47A-T86 (Al-Cu-Li) and 7075-T651 (Al-Zn-Mg-Cu), used in aerospace structures are susceptible to environment assisted fatigue crack propagation (EFCP) by hydrogen environment embrittlement. This research demonstrates effective inhibition of EFCP in C47A-T86 and 7075-T651 under both full immersion in aqueous chloride solution and atmospheric exposure which more accurately describes aircraft service conditions. Inhibition is attributed to the presence of a crack tip passive film reducing H production and uptake, as explained by the film rupture-hydrogen embrittlement mechanism, and can be accomplished through both addition of a passivating ion (ion-assisted inhibition) and localized-alloy corrosion creating passivating conditions (self inhibition). Addition of molybdate to both bulk chloride solution and surface chloride droplets eliminates the effect of environment on fatigue crack propagation in C47A-T86 and 7075-1651 at sufficiently low loading frequencies and high stress ratio by yielding crack growth rates equivalent to those for fatigue in ultra high vacuum. The preeminent corrosion inhibitor, chromate, has not been reported to produce such complete inhibition. Inhibition is promoted by reduced loading frequency, increased crack tip molybdate concentration, and potential at or anodic to free corrosion; each of which favors passivity. The inhibiting effect of molybdate parallels chromate, establishing molybdate as a viable chromate replacement inhibitor. The ability of molybdate to inhibit EFCP is enhanced by atmospheric exposures producing surface electrolyte droplets; crack growth rates are reduced by an order of magnitude under loading frequencies as high as 30 Hz, a frequency at which inhibition was not possible under full immersion. Al-Cu-Mg/Li alloys, including 2024-T351, are capable of self inhibition of EFCP. This behavior is attributed to localized corrosion through dealloying of anodic Al2CuMg or Al2Cu

  9. Tensile Properties and Work Hardening Behavior of Laser-Welded Dual-Phase Steel Joints

    NASA Astrophysics Data System (ADS)

    Farabi, N.; Chen, D. L.; Zhou, Y.

    2012-02-01

    The aim of this investigation was to evaluate the microstructural change after laser welding and its effect on the tensile properties and strain hardening behavior of DP600 and DP980 dual-phase steels. Laser welding led to the formation of martensite and significant hardness rise in the fusion zone because of the fast cooling, but the presence of a soft zone in the heat-affected zone was caused by partial vanishing and tempering of the pre-existing martensite. The extent of softening was much larger in the DP980-welded joints than in the DP600-welded joints. Despite the reduction in ductility, the ultimate tensile strength (UTS) remained almost unchanged, and the yield strength (YS) indeed increased stemming from the appearance of yield point phenomena after welding in the DP600 steel. The DP980-welded joints showed lower YS and UTS than the base metal owing to the appearance of severe soft zone. The YS, UTS, and strain hardening exponent increased slightly with increasing strain rate. While the base metals had multi-stage strain hardening, the welded joints showed only stage III hardening. All the welded joints failed in the soft zone, and the fracture surfaces exhibited characteristic dimple fracture.

  10. Precipitation of β' phase and hardening in dental-casting Ag-20Pd-12Au-14.5Cu alloys subjected to aging treatments.

    PubMed

    Kim, Yonghwan; Niinomi, Mitsuo; Hieda, Junko; Nakai, Masaaki; Cho, Ken; Fukui, Hisao

    2014-03-01

    The age-hardening behavior of the dental-casting Ag-20Pd-12Au-14.5Cu alloy subjected to aging treatment at around 673K is well known, and this hardening has been widely employed in various applications. To date, the age-hardening of this alloy has been explained to attribute to the precipitation of a β phase, which is a B2-type ordered CuPd phase or PdCuxZn1-x phase. In this study, results obtained from microstructural observations using a transmission electron microscopy and a scanning transmission electron microscopy revealed that a fine L10-type ordered β' phase precipitated in the matrix and a coarse-structure region (consisting of Ag- and Cu-rich regions) appeared after aging treatment at 673K and contributed to increase in hardness. The microstructure of the coarse β phase, which existed before aging treatment, did not change by aging treatment. Thus, it is concluded that the fine β' phase precipitated by aging treatment contributed more to increase in hardness than the coarse-structure region and coarse β phase.

  11. Developing Processing Routes for the Equal-Channel Angular Pressing of Age-Hardenable Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Duan, Zhi Chao; Chinh, Nguyen Q.; Xu, Cheng; Langdon, Terence G.

    2010-04-01

    The processing of age-hardenable aluminum alloys by equal-channel angular pressing (ECAP) was investigated using three different Al-Zn-Mg alloys. The results show that it is relatively easy to conduct the ECAP at an elevated temperature of 473 K, but this leads to a weakening of the alloy rather than a strengthening. The processing by ECAP may be performed successfully at room temperature provided it is conducted fairly quickly (within ~10 minutes) after quenching from the solution treatment. It is necessary also to optimize the solution treatment conditions for each alloy composition. Under optimum conditions, good strengthening is achieved even after a single pass in ECAP.

  12. Transmission and scanning electron microscope study on the secondary cyclic hardening behavior of interstitial-free steel

    SciTech Connect

    Shih, Chia-Chang; Ho, New-Jin; Huang, Hsing-Lu

    2009-11-15

    Strain controlled fatigue experiment was employed to evaluate automotive grade interstitial-free ferrite steel. Hundreds of grains were examined by scanning electron microscope under electron channeling contrast image technique of backscattered electron image mode for comprehensive comparison of micrographs with those taken under transmission electron microscope. The cyclic stress responses clearly revealed that rapid hardening occurs at the early stage of cycling as a result of multiplication of dislocations to develop loop patches, dipolar walls and dislocation cells at various total strain amplitudes. After primary rapid hardening, stress responses varied from being saturated to further hardening according to dislocation structure evolution at various strain amplitudes. The fatigue failure was always accompanied with further hardening including secondary hardening. The corresponding dislocation structures with the three types of hardening behaviors are discussed. Once the secondary hardening starts, dislocation cells began to develop along grain boundaries in the low strain region and then extended into grain interiors as strain amplitudes increased and cycling went on. The secondary hardening rates were found to be directly proportional to their strain amplitudes.

  13. 3D dislocation dynamics: stress-strain behavior and hardening mechanisms in FCC and BCC metals

    SciTech Connect

    Hirth, J P; Rhee, M; Zhib, H M; de la Rubia, T D

    1999-02-19

    A dislocation dynamics (DD) model for plastic deformation, connecting the macroscopic mechanical properties to basic physical laws governing dislocation mobility and related interaction mechanisms, has been under development. In this model there is a set of critical reactions that determine the overall results of the simulations, such as the stress-strain curve. These reactions are, annihilation, formation of jogs, junctions, and dipoles, and cross-slip. In this paper we discuss these reactions and the manner in which they influence the simulated stress- strain behavior in fcc and bcc metals. In particular, we examine the formation (zipping) and strength of dipoles and junctions, and effect of jogs, using the dislocation dynamics model. We show that the strengths (unzipping) of these reactions for various configurations can be determined by direct evaluation of the elastic interactions. Next, we investigate the phenomenon of hardening in metals subjected to cascade damage dislocations. The microstructure investigated consists of small dislocation loops decorating the mobile dislocations. Preliminary results reveal that these loops act as hardening agents, trapping the dislocations and resulting in increased hardening.

  14. Dry and clean age hardening of aluminum alloys by high-pressure gas quenching

    NASA Astrophysics Data System (ADS)

    Irretier, A.; Kessler, O.; Hoffmann, F.; Mayr, P.

    2004-10-01

    When precipitation-hardenable aluminum parts are water quenched, distortion occurs due to thermal stresses. Thereby, a costly reworking is necessary, and for this reason polymer quenchants are often used to reduce distortion, with the disadvantage that the quenched parts have to be cleaned after quenching. In opposition to liquid quenchants, gas quenching may decrease distortion due to the better temperature uniformity during quenching. Furthermore, cleaning of the quenched parts can be avoided because it is a dry process. For this purpose, a heat-treating process was evaluated that included a high-pressure gasquenching step. Gas quenching was applied to different aluminum alloys (i.e., 2024, 6013, 7075, and A357.0), and tensile tests have been carried out to determine the mechanical properties after solution annealing, gas quenching, and aging. Besides high-pressure gas quenching, alloy 2024 was quenched at ambient pressure in a gas nozzle field. The high velocity at the gas outlet leads to an accelerated cooling of the aluminum alloy in this case. Aluminum castings and forgings can be classified as an interesting field of application of these quenching methods due to their near-net shape before the heat treatment. Cost savings would be possible due to the reduced distortion, and therefore, less reworking after the precipitation hardening.

  15. The double effect of grain size on the work hardening behavior of polycrystalline copper

    SciTech Connect

    Gracio, J.J. . Dept. de Engenharia Mecanica)

    1994-08-15

    Following the approach by Ashby, one can consider that strain compatibility between adjacent grains of a polycrystal generates geometrical dislocations. These dislocations participated in the strengthening mechanism in conjunction with statistically stored dislocations which are related to the single-crystal behavior. The dislocations of either species are indistinguishable and, as a whole, they may contribute to cell formation. The dislocation structure formed in a polycrystal is then a function of the major or minor intergranular accommodation complexity. At intermediate strain values the accommodation is distributed over the cells leading to a linear relationship between the tensile stress and the inverse of the cell size, whatever the grain size of the tested samples. The aim of the present work is to check that the presence of statistical and geometrical dislocations in the grains, as well as the fact that at the very early stage of plastic deformation the mean free path of dislocations is of the order of the grain size, leads to a double effect of the grain size on the work hardening behavior of polycrystalline copper. Moreover, careful analysis of the mechanical behavior of polycrystalline copper, including the microstructural aspects of plastic deformation, is performed, allowing the understanding of the relationship between the work hardening ratio and the grain size.

  16. Fatigue Hardening Behavior of 1.5 GPa Grade Transformation-Induced Plasticity-Aided Martensitic Steel

    NASA Astrophysics Data System (ADS)

    Sugimoto, Koh-Ichi; Hojo, Tomohiko

    2016-11-01

    Low cycle fatigue hardening/softening behavior of a 0.2 pct C-1.5 pct Si-1.5 pct Mn-1.0 pct Cr-0.2 pct Mo-0.05 pct Nb transformation-induced plasticity (TRIP)-aided steel consisting of a wide lath martensite structure matrix and a narrow lath martensite-metastable retained austenite mixture was investigated. The steel exhibited notable fatigue hardening in the same way as TRIP-aided bainitic ferrite steel, although conventional martensitic steel such as SCM420 steel with the same tensile strength exhibited fatigue softening. The considerable fatigue hardening of this steel is believed to be associated mainly with the compressive internal stress that results from a difference in flow stress between the matrix and the martensite-austenite-like phase, with a small contribution from the strain-induced transformation and dislocation hardenings.

  17. Preservation of reproductive behaviors during modest cooling: rapid cold-hardening fine-tunes organismal response.

    PubMed

    Shreve, Scott M; Kelty, Jonathan D; Lee, Richard E

    2004-05-01

    The primary objectives of this study were to determine (1) whether rapid cold-hardening (RCH) preserves reproductive behaviors during modest cooling, (2) whether increased mating success at a lower temperature comes at the cost of decreased performance at a higher temperature and (3) whether RCH is associated with an elevated metabolic rate. Drosophila melanogaster (Diptera: Drosphilidae) were rapidly cold-hardened by a 2-h exposure to 16 degrees C prior to experiments. A temperature decrease of only 7 degrees C (23 degrees C to 16 degrees C) prevented half (11/22) of the control pairs of D. melanogaster from engaging in any courtship activity. By contrast, most RCH pairs courted (17/20). Additionally, the 7 degrees C transfer prevented mating in every pair of control flies, whereas more than half (11/20) of the RCH pairs mated. There was no evidence of impaired courtship or mating performance when RCH pairs were tested at 23 degrees C. Finally, RCH is apparently not an energy-demanding process because no increase in the metabolic rate was detected during its induction. Overall, these data demonstrate that RCH serves to constantly fine-tune an insect's physiological state to match slight changes in environmental temperature. Furthermore, the RCH response is not restricted to cryoprotection and survival in the cold but also preserves more subtle behaviors, such as courtship, at moderate to high temperatures throughout the year. PMID:15107435

  18. Hardening mechanisms in a dynamic strain aging alloy, Hastelloy X, during isothermal and thermomechanical cyclic deformation

    NASA Technical Reports Server (NTRS)

    Miner, R. V.; Castelli, M. G.

    1992-01-01

    The relative contributions of the hardening mechanisms in Hastelloy X during cyclic deformation were investigated by conducting isothermal cyclic deformation tests within a total strain range of +/-0.3 pct and at several temperatures and strain rates, and thermomechanical tests within several different temperature limits. The results of the TEM examinations and special constant structure tests showed that the precipitation on dislocations of Cr23C6 contributed to hardening, but only after sufficient time above 500 C. Solute drag alone produced very considerable cyclic hardening. Heat dislocation densities, peaking around 10 exp 11 per sq cm, were found to develop at temperatures producing the greatest cyclic hardening.

  19. Thermomechanical cyclic hardening behavior of Hastelloy-X. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Bartolotta, P. A.

    1985-01-01

    Experimental evidence of thermomechanical history dependence on the cyclic hardening behavior of a representative combustor liner material Hastelloy-X is presented, along with a discussion about the relevant concept of thermomechanical path dependence. Based on the experimental results, a discussion is given on the inadequacy of formulating nonisothermal constitutive equations solely on the basis of isothermal testing. Finally, the essence of a mathematical representation of thermoviscoplasticity is presented that qualitatively accounts for the observed hereditary behavior. This is achieved by formulating the scaler evolutionary equation in an established viscoplastic theory to reflect thermomechanical path dependence. Although the necessary nonisothermal tests for further quantifying the thermoviscoplastic model have been identified, such data are not yet available.

  20. Hardening behavior after high-temperature solution treatment of Ag-20Pd-12Au-xCu alloys with different Cu contents for dental prosthetic restorations.

    PubMed

    Kim, Yonghwan; Niinomi, Mitsuo; Hieda, Junko; Nakai, Masaaki; Cho, Ken; Fukui, Hisao

    2014-07-01

    Ag-Pd-Au-Cu alloys have been used widely for dental prosthetic applications. Significant enhancement of the mechanical properties of the Ag-20Pd-12Au-14.5Cu alloy as a result of the precipitation of the β' phase through high-temperature solution treatment (ST), which is different from conventional aging treatment in these alloys, has been reported. The relationship between the unique hardening behavior and precipitation of the β' phase in Ag-20Pd-12Au-xCu alloys (x=6.5, 13, 14.5, 17, and 20mass%) subjected to the high-temperature ST at 1123K for 3.6ks was investigated in this study. Unique hardening behavior after the high-temperature ST also occurs in Ag-20Pd-12Au-xCu alloys (x=13, 17, and 20) with precipitation of the β' phase. However, hardening is not observed and the β' phase does not precipitate in the Ag-20Pd-12Au-6.5Cu alloy after the same ST. The tensile strength and 0.2% proof stress also increase in Ag-20Pd-12Au-xCu alloys (x=13, 14.5, 17, and 20) after the high-temperature ST. In addition, these values after the high-temperature ST increase with increasing Cu content in Ag-20Pd-12Au-xCu alloys (x=14.5, 17, and 20). The formation process of the β' phase can be explained in terms of diffusion of Ag and Cu atoms and precipitation of the β' phase. Clarification of the relationship between hardening and precipitation of the β' phase via high-temperature ST is expected to help the development of more effective heat treatments for hardening in Ag-20Pd-12Au-xCu alloys.

  1. Explosion in the Granite Field: Hardening and Softening Behavior in Rocks

    SciTech Connect

    Lomov, I N; Antoun, T H; Glenn, L A

    2001-07-12

    Properties of rock materials under quasistatic conditions are well characterized in laboratory experiments. Unfortunately, quasistatic data alone are not sufficient to calibrate models for use to describe inelastic wave propagation associated with conventional and nuclear explosions, or with impact. First, rock properties are size-dependent. properties measured using laboratory samples on the order of a few centimeters in size need to be modified to adequately describe wave propagation in a problem on the order of a few hundred meters in size. Second, there is lack of data about the damage (softening) behavior of rock because most laboratory tests focus on the pre-peak hardening region with very little emphasis on the post-peak softening region. This paper presents a model for granite that accounts for both the hardening and softening of geologic materials, and also provides a simple description of rubblized rock. The model is shown to reproduce results of quasistatic triaxial experiments as well as peak velocity and peak displacement attenuation from a compendium of dynamic wave propagation experiments that includes US and French nuclear tests in granite.

  2. The effect of particulate oxidation on the age-hardening characteristics of SiC/6061 MMC produced by the preform infiltration route

    SciTech Connect

    Towle, D.J.; Friend, C.H. )

    1992-02-01

    The behavior of a metal matrix composite based on 6061 alloy was investigated with a view to identifying the relative contributions of the processing temperatures and the level of particulate oxidation to magnesium depletion as a result of a chemical reaction between SiO2 particulates and matrix magnesium. The speed and the extent of the reaction are found to depend on both the thermal conditions of infiltration and the net SiO2 content of the preform. Both factors should therefore be as low as possible to maximize the age-hardening response of the composite. 11 refs.

  3. Effect of Hf on structure and age hardening of Ti–Al-N thin films

    PubMed Central

    Rachbauer, R.; Blutmager, A.; Holec, D.; Mayrhofer, P.H.

    2012-01-01

    Protective coatings for high temperature applications, as present e.g. during cutting and milling operations, require excellent mechanical and thermal properties during work load. The Ti1 − xAlxN system is industrially well acknowledged as it covers some of these requirements, and even exhibits increasing hardness with increasing temperature in its cubic modification, known as age hardening. The thermally activated diffusion at high temperatures however enables for the formation of wurtzite AlN, which causes a rapid reduction of mechanical properties in Ti1 − xAlxN coatings. The present work investigates the possibility to increase the formation temperature of w-AlN due to Hf alloying up to 10 at.% at the metal sublattice of Ti1 − xAlxN films. Ab initio predictions on the phase stability and decomposition products of quaternary Ti1 − x − yAlxHfyN alloys, as well as the ternary Ti1 − xAlxN, Hf1 − xAlxN and Ti1 − zHfzN systems, facilitate the interpretation of the experimental findings. Vacuum annealing treatments from 600 to 1100 °C indicate that the isostructural decomposition, which is responsible for age hardening, of the Ti1 − x − yAlxHfyN films starts at lower temperatures than the ternary Ti1 − xAlxN coating. However, the formation of a dual phase structure of c-Ti1 − zHfzN (with z = y/(1 − x)) and w-AlN is shifted to ~ 200 °C higher temperatures, thus retaining a film hardness of ~ 40 GPa up to ~ 1100 °C, while the Hf free films reach the respective hardness maximum of ~ 38 GPa already at ~ 900 °C. Additional annealing experiments at 850 and 950 °C for 20 h indicate a substantial improvement of the oxidation resistance with increasing amount of Hf in Ti1 − x − yAlxHfyN. PMID:22319223

  4. Evaluation of hardening behaviors in ion-irradiated Fe-9Cr and Fe-20Cr alloys by nanoindentation technique

    NASA Astrophysics Data System (ADS)

    Li, Shilei; Wang, Yanli; Dai, Xianyuan; Liu, Fang; Li, Jinyu; Wang, Xitao

    2016-09-01

    The ion irradiation hardening behaviors of Fe-9 wt% Cr and Fe-20 wt% Cr model alloys were investigated by nanoindentation technique. The specimens were irradiated with 3 MeV Fe11+ ions at room temperature up to 1 and 5 dpa for Fe-9Cr alloy and 1 and 2.5 for Fe-20Cr alloy. The ratio of average hardness in the same depth of irradiated and unirradiated (Hirr. av/Hunirr. av) was used to determine the critical indentation depth hcrit to eliminate the softer substrate effect. The Nix-Gao model was used to explain the indentation size effect. Irradiation hardening is clearly observed in both Fe-9Cr alloy and Fe-20Cr alloy after ion irradiation. The differences of ISE and irradiation hardening behaviors between Fe-9Cr and Fe-20Cr alloys are considered to be due to their different microstructures and microstructural evolution under ion irradiation.

  5. Microstructure and Mechanical Behavior of 17-4 Precipitation Hardenable Steel Processed by Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Rafi, H. Khalid; Pal, Deepankar; Patil, Nachiket; Starr, Thomas L.; Stucker, Brent E.

    2014-12-01

    The mechanical behavior and the microstructural evolution of 17-4 precipitation hardenable (PH) stainless steel processed using selective laser melting have been studied. Test coupons were produced from 17-4 PH stainless steel powder in argon and nitrogen atmospheres. Characterization studies were carried out using mechanical testing, optical microscopy, scanning electron microscopy, and x-ray diffraction. The results show that post-process heat treatment is required to obtain typically desired tensile properties. Columnar grains of smaller diameters (<2 µm) emerged within the melt pool with a mixture of martensite and retained austenite phases. It was found that the phase content of the samples is greatly influenced by the powder chemistry, processing environment, and grain diameter.

  6. Influence of cold rolling degree and ageing treatments on the precipitation hardening of 2024 and 7075 alloys

    NASA Astrophysics Data System (ADS)

    Naimi, A.; Yousfi, H.; Trari, M.

    2013-08-01

    In the present work, the precipitation hardening of 2024 and 7075 aluminum alloys is investigated as a function of cold rolling degree, ageing time and temperature using Vickers microhardness measurements and differential scanning calorimetry (DSC). It is found that a variation in such parameters can improve the hardness and plays an important role in the precipitation hardening process. At specific ageing temperature, the large cold rolled 7075 alloy exhibits two peaks of hardness. Moreover, for both alloys, the increment of hardness during ageing decreases with increasing the cold rolling degree. While in some cases microhardness measurements give impression that the precipitation reaction is slowed down by deformation, DSC analysis indicates that the precipitation is much accelerated since only a slight deformation decreases strongly the temperatures of reactions. However, the degree of cold rolling does not play a crucial role.

  7. The effect of twinning on the work hardening behavior in Hafnium

    SciTech Connect

    Cerreta, E. K.; Gray, G. T. , III; Yablinsky, C.

    2004-01-01

    In many HCP metals, both twinning and slip are known to be important modes of deformation. However, the interaction of the two mechanisms and their effect on work hardening is not well understood. In hafnium, twinning and work hardening rates increase with increasing strain, increasing strain rate, and decreasing temperature. At low strains and strain rates and at higher temperatures, slip dominates deformation and rates of work hardening are relatively lower. To characterize the interaction of slip and twinning, Hf specimens were prestrained quasi-statically in compression at 77K, creating specimens that were heavily twinned. These specimens were subsequently reloaded at room temperature. Twinning within the microstructures was characterized optically and using transmission electron microscopy. The interaction of slip with the twins was investigated as a function of prestrain and correlated with the observed rates of work hardening.

  8. Aging behavior and mechanical properties of maraging steels in the presence of submicrocrystalline Laves phase particles

    SciTech Connect

    Mahmoudi, A.; Ghavidel, M.R. Zamanzad; Nedjad, S. Hossein; Heidarzadeh, A.; Ahmadabadi, M. Nili

    2011-10-15

    Cold rolling and annealing of homogenized Fe-Ni-Mn-Mo-Ti-Cr maraging steels resulted in the formation of submicrocrystalline Fe{sub 2}(Mo,Ti) Laves phase particles. Optical and scanning electron microscopy, X-ray diffraction, tensile and hardness tests were used to study the microstructure, aging behavior and mechanical properties of the annealed steels. The annealed microstructures showed age hardenability during subsequent isothermal aging at 753 K. Ultrahigh fracture stress but poor tensile ductility was obtained after substantial age hardening in the specimens with 2% and 4% chromium. Increasing chromium addition up to 6% toughened the aged microstructure at the expense of the fracture stress by increasing the volume fraction of retained austenite. The Laves phase particles acted as crack nucleation sites during tensile deformation. - Highlights: {yields} Laves phases dispersed in a BCC iron matrix by annealing of cold rolled samples. {yields} The samples showed age hardenability during subsequent isothermal aging at 753 K. {yields} Ultrahigh fracture stress but poor ductility was obtained after age hardening. {yields} Increasing chromium addition toughened the aged microstructure. {yields} Laves phase particles acting as crack nucleation sites during tensile deformation.

  9. Significant contribution of stacking faults to the strain hardening behavior of Cu-15%Al alloy with different grain sizes.

    PubMed

    Tian, Y Z; Zhao, L J; Chen, S; Shibata, A; Zhang, Z F; Tsuji, N

    2015-11-19

    It is commonly accepted that twinning can induce an increase of strain-hardening rate during the tensile process of face-centered cubic (FCC) metals and alloys with low stacking fault energy (SFE). In this study, we explored the grain size effect on the strain-hardening behavior of a Cu-15 at.%Al alloy with low SFE. Instead of twinning, we detected a significant contribution of stacking faults (SFs) irrespective of the grain size even in the initial stage of tensile process. In contrast, twinning was more sensitive to the grain size, and the onset of deformation twins might be postponed to a higher strain with increasing the grain size. In the Cu-15 at.%Al alloy with a mean grain size of 47 μm, there was a stage where the strain-hardening rate increases with strain, and this was mainly induced by the SFs instead of twinning. Thus in parallel with the TWIP effect, we proposed that SFs also contribute significantly to the plasticity of FCC alloys with low SFE.

  10. Hardening of the arteries

    MedlinePlus

    Atherosclerosis; Arteriosclerosis; Plaque buildup - arteries; Hyperlipidemia - atherosclerosis; Cholesterol - atherosclerosis ... Hardening of the arteries often occurs with aging. As you grow older, ... narrows your arteries and makes them stiffer. These changes ...

  11. Unveiling the Origin of Work Hardening Behavior in an Ultrafine-Grained Manganese Transformation-Induced Plasticity Steel by Hydrogen Investigation

    NASA Astrophysics Data System (ADS)

    Zhu, Xu; Li, Wei; Zhao, Hongshan; Han, Qihang; Wang, Li; Jiao, Huisheng; Jin, Xuejun

    2016-09-01

    To reveal the origin of work hardening behavior in an ultrafine-grained manganese transformation-induced plasticity (TRIP) steel, specific experiments were designed with the assistance of hydrogen. Although the effect of hydrogen on the austenite transformation was negligible, the work hardening rate ( Θ) was apparently reduced for hydrogenated samples, indicating that TRIP effect cannot account for the high Θ alone. The collaborative effect of dislocation accumulation in ferrite and austenite transformation is proposed to explain the responsible mechanism.

  12. The Strain-Hardening Behavior of Partially Austenitized and the Austempered Ductile Irons with Dual Matrix Structures

    NASA Astrophysics Data System (ADS)

    Kilicli, Volkan; Erdogan, Mehmet

    2008-04-01

    In the current study, an unalloyed ductile iron containing 3.50 C wt.%, 2.63 Si wt.%, 0.318 Mn wt.%, and 0.047 Mg wt.% was intercritically austenitized (partially austenitized) in two-phase regions (α + γ) at different temperatures for 20 min and then was quenched into salt bath held at austempering temperature of 365 °C for various times to obtain different ausferrite plus proeutectoid ferrite volume fractions. Fine and coarse dual matrix structures (DMS) were obtained from two different starting conditions. Some specimens were also conventionally austempered from 900 °C for comparison. The results showed that a structure having proeutectoid ferrite plus ausferrite (bainitic ferrite + high-carbon austenite (retained or stabilized austenite)) has been developed. Both of the specimens with ˜75% ausferrite volume fraction (coarse structure) and the specimen with ˜82% ausferrite volume fraction (fine structure) exhibited the best combination of high strength and ductility compared to the pearlitic grades, but their ductility is slightly lower than the ferritic grades. These materials also satisfy the requirements for the strength of the quenched and tempered grades and their ductility is superior to this grade. The correlation between the strain-hardening rates of the various austempered ductile iron (ADI) with DMS and conventionally heat-treated ADI microstructures as a function of strain was conducted by inspection of the respective tensile curves. For this purpose, the Crussard-Jaoul (C-J) analysis was employed. The test results also indicate that strain-hardening behavior of ADI with dual matrix is influenced by the variations in the volume fractions of the phases, and their morphologies, the degree of ausferrite connectivity and the interaction intensities between the carbon atoms and the dislocations in the matrix. The ADI with DMS generally exhibited low strain-hardening rates compared to the conventionally ADI.

  13. The effects of solution treatment on the mechanical properties of age-hardened A-286 bar stock at elevated and cryogenic temperature

    NASA Technical Reports Server (NTRS)

    Montano, J. W.

    1972-01-01

    The mechanical properties are presented of solution treated and age hardened A-286 corrosion resistant steel bar stock. Material solution treated at 899 C or 982 C, each followed by an age hardening treatment of 718 C, was evaluated. Test specimens manufactured from 1.50 inch (3.81 cm) diameter bar stock were tested at temperatures from +649 C to -253 C. The test data indicated excellent tensile, yield, elongation and reduction-in-area properties at all testing temperatures for both solution treated and aged materials. Cryogenic temperature notched tensile, impact, and shear tests indicated excellent notch strength, ductility, and shear values. There was very little difference in the mechanical properties of the two solution treated and aged materials. The only exception was that the 962 C solution treated and aged material had superior stress rupture properties at 649 C.

  14. Impact properties and hardening behavior of laser and electron-beam welds of V-4Cr-4Ti

    SciTech Connect

    Chung, H.M.; Strain, R.V.; Tsai, H.C.; Park, J.H.; Smith, D.L.

    1996-10-01

    The authors are conducting a program to develop an optimal laser welding procedure that can be applied to large-scale fusion-reactor structural components to be fabricated from vanadium-base alloys. Results of initial investigation of mechanical properties and hardening behavior of laser and electron-beam (EB) welds of the production-scale heat of V-4Cr-4Ti (500-kg Heat 832665) in as-welded and postwelding heat-treated (PWHT) conditions are presented in this paper. The laser weld was produced in air using a 6-kW continuous CO{sub 2} laser at a welding speed of {approx}45 mm/s. Microhardness of the laser welds was somewhat higher than that of the base metal, which was annealed at a nominal temperature of {approx}1050{degrees}C for 2 h in the factory. In spite of the moderate hardening, ductile-brittle transition temperatures (DBTTs) of the initial laser ({approx}80{degrees}C) and EB ({approx}30{degrees}C) welds were significantly higher than that of the base metal ({approx}{minus}170{degrees}C). However, excellent impact properties, with DBTT < {minus}80{degrees}C and similar to those of the base metal, could be restored in both the laser and EB welds by postwelding annealing at 1000{degrees}C for 1 h in vacuum.

  15. Measurement of Work Hardening Behavior of Pure Titanium Sheet Using A Servo-Controlled Tube Bulge Testing Apparatus

    SciTech Connect

    Sumita, Takeshi; Kuwabara, Toshihiko; Hayashida, Yasuhiro

    2011-05-04

    Biaxial stress tests of rolled pure titanium sheet (JIS 1, 0.5 mm thick) have been carried out in order to investigate the anisotropic plastic deformation under biaxial tension. Rolled pure titanium sheet was bent and welded to make tubular specimens. Combined tension-internal pressure was applied to the tubular specimens using the servo-controlled tube bulge testing apparatus developed by one of the authors [Kuwabara, T., Yoshida, K., Narihara, K., Takahashi S., Int. J. Plasticity 21 (1), 101-117 (2002)], so that the strain rate ratio, {epsilon}{sub {phi}}:{epsilon}{theta}, in the axial ({phi}) and circumferential ({theta}) directions of the specimen was controlled to be constant. Contours of plastic work at different levels of plastic strain and stress paths under constant strain rate ratios have been observed in the first quadrant of stress space. It is found that the test material exhibits significant differential work hardening behavior with the increase of plastic work.

  16. Age Related Changes in Preventive Health Behavior.

    ERIC Educational Resources Information Center

    Leventhal, Elaine A.; And Others

    Health behavior may be influenced by age, beliefs, and symptomatology. To examine age-related health beliefs and behaviors with respect to six diseases (the common cold, colon-rectal cancer, lung cancer, heart attack, high blood pressure, and senility), 396 adults (196 males, 200 females) divided into three age groups completed a questionnaire…

  17. Healthy Behaviors or Age Denials?

    ERIC Educational Resources Information Center

    Palmore, Erdman B.

    2007-01-01

    There is considerable confusion in the media and the public about healthy behaviors in contrast to "antiaging" behaviors designed to make one look "younger." As an aid in clarifying the differences between these two types of behaviors, we have developed a questionnaire called the Health Behavior Inventory (HBI). We also wanted to estimate…

  18. Age hardening in rapidly solidified and hot isostatically pressed beryllium-aluminum-silver alloys

    SciTech Connect

    Carter, D.H.; McGeorge, A.C.; Jacobson, L.A.; Stanek, P.W.

    1995-07-01

    Three different alloys of beryllium, aluminum and silver were processed to powder by centrifugal atomization in a helium atmosphere. Alloy compositions were, by weight, 50% Be, 47.5% Al, 2.5% Ag, 50% Be, 47% Al, 3% Ag, and 50% Be, 46% Al, 4% Ag. Due to the low solubility of both aluminum and silver in beryllium, the silver was concentrated in the aluminum phase, which appeared to separate from the beryllium in the liquid phase. A fine, continuous composite beryllium-aluminum microstructure was formed, which did not significantly change after hot isostatically pressing at 550 C for one hour at 30,000 psi argon pressure. Samples of HIP material were solution treated at 550 C for one hour, followed by a water quench. Aging temperatures were 150, 175, 200 and 225 C for times ranging from one half hour to 65 hours. Hardness measurements were made using a diamond pyramid indenter with a load of 1 kg. Results indicate that peak hardness was reached in 36--40 hours at 175 C and 12--16 hours at 200 C aging temperature, relatively independent of alloy composition.

  19. Effect of Texture on Fatigue Properties of Age-Hardened Al Alloys Under Ultrasonic Loading

    NASA Astrophysics Data System (ADS)

    Matsusako, Hironori; Kariya, Kohji; Kawagoishi, Norio; Wang, Qingyuan; Goto, Masahiro

    Effects of texture and loading frequency on the fatigue crack growth behavior of an extruded and a drawn Al alloys of 2017-T4 were investigated under ultrasonic loading frequency (20kHz) in the relative humidity of 25% and 85%, respectively. The extruded alloy has a marked texture of (111) orientation, but this specified orientation is not observed in the drawn alloy. Most of fatigue life was occupied by the growth life of small cracks in the both alloys regardless of humidity. In the low humidity, crack growth was retarded at about 0.3 mm in length in the both alloys. Although crack growth was accelerated by high humidity in the early growth process, there was no or little influence of humidity on the growth rate of cracks over about 0.3 mm in the both alloys. After the retardation of crack growth, fracture surfaces featured with many slip planes in the extruded alloy and many facets in the drawn one, respectively. The difference in growth mechanism between short cracks (<0.3 mm) and longer ones (>0.3 mm) was caused by the environment at crack tips due to high crack growth rate under ultrasonic loading, and that between the both alloys was related to the degree of texture.

  20. Initial precipitation and hardening mechanism during non-isothermal aging in an Al–Mg–Si–Cu 6005A alloy

    SciTech Connect

    Yang, Wenchao; Ji, Shouxun; Huang, Lanping; Sheng, Xiaofei; Li, Zhou; Wang, Mingpu

    2014-08-15

    The characterization of precipitation and hardening mechanism during non-isothermal aging had been investigated using high resolution transmission electron microscopy for an Al–Mg–Si–Cu 6005A alloy. It was proposed that the needle-shaped β″ precipitates with a three-dimension coherency strain-field and an increased number density in the Al matrix provided the maximum strengthening effect for the Al–Mg–Si–Cu 6005A alloy. Simultaneously, it was also found that the formation and evolution of clusters in the early precipitation were associated with the vacancy binding energy, during which Si atoms played an important role in controlling the numbers density of Mg/Si co-clusters, and the excess Si atoms provided the increased number of nucleation sites for the subsequent precipitates to strengthen and improve the precipitation rate. Finally, based on the experimental observation and theoretical analysis, the precipitation sequence during the early precipitation in the Al–Mg–Si–Cu 6005A alloy was proposed as: supersaturated solid solution → Si-vacancy pairs, Mg-vacancy pairs and Mg clusters → Si clusters, and dissolution of Mg clusters → Mg atoms diffusion into the existing Si clusters → Mg/Si co-clusters → GP zone. - Highlights: • β″ precipitates provide the maximum strengthening effect for the 6005A alloy. • Si atoms play an important role in controlling the numbers of Mg/Si co-clusters. • The early aging sequence is deduced based on the solute-vacancy binding energy.

  1. Evaluation of Solute Clusters Associated with Bake-Hardening Response in Isothermal Aged Al-Mg-Si Alloys Using a Three-Dimensional Atom Probe

    NASA Astrophysics Data System (ADS)

    Aruga, Yasuhiro; Kozuka, Masaya; Takaki, Yasuo; Sato, Tatsuo

    2014-12-01

    Temporal changes in the number density, size distribution, and chemical composition of clusters formed during natural aging at room temperature and pre-aging at 363 K (90 °C) in an Al-0.62Mg-0.93Si (mass pct) alloy were evaluated using atom probe tomography. More than 10 million atoms were examined in the cluster analysis, in which about 1000 clusters were obtained for each material after various aging treatments. The statistically proven records show that both number density and the average radius of clusters in pre-aged materials are larger than in naturally aged materials. It was revealed that the fraction of clusters with a low Mg/Si ratio after natural aging for a short time is higher than with other aging treatments, regardless of cluster size. This indicates that Si-rich clusters form more easily after short-period natural aging, and that Mg atoms can diffuse into the clusters or possibly form another type of Mg-Si cluster after prolonged natural aging. The formation of large clusters with a uniform Mg/Si ratio is encouraged by pre-aging. It can be concluded that an increase of small clusters with various Mg/Si ratios does not promote the bake-hardening (BH) response, whereas large clusters with a uniform Mg/Si ratio play an important role in hardening during the BH treatment at 443 K (170 °C).

  2. Evaluation of Solute Clusters Associated with Bake-Hardening Response in Isothermal Aged Al-Mg-Si Alloys Using a Three-Dimensional Atom Probe

    NASA Astrophysics Data System (ADS)

    Aruga, Yasuhiro; Kozuka, Masaya; Takaki, Yasuo; Sato, Tatsuo

    2014-09-01

    Temporal changes in the number density, size distribution, and chemical composition of clusters formed during natural aging at room temperature and pre-aging at 363 K (90 °C) in an Al-0.62Mg-0.93Si (mass pct) alloy were evaluated using atom probe tomography. More than 10 million atoms were examined in the cluster analysis, in which about 1000 clusters were obtained for each material after various aging treatments. The statistically proven records show that both number density and the average radius of clusters in pre-aged materials are larger than in naturally aged materials. It was revealed that the fraction of clusters with a low Mg/Si ratio after natural aging for a short time is higher than with other aging treatments, regardless of cluster size. This indicates that Si-rich clusters form more easily after short-period natural aging, and that Mg atoms can diffuse into the clusters or possibly form another type of Mg-Si cluster after prolonged natural aging. The formation of large clusters with a uniform Mg/Si ratio is encouraged by pre-aging. It can be concluded that an increase of small clusters with various Mg/Si ratios does not promote the bake-hardening (BH) response, whereas large clusters with a uniform Mg/Si ratio play an important role in hardening during the BH treatment at 443 K (170 °C).

  3. Transmission Electron Microscopy Characterization of the Bake-Hardening Behavior of Transformation-Induced Plasticity and Dual-Phase Steels

    NASA Astrophysics Data System (ADS)

    Timokhina, I. B.; Hodgson, P. D.; Pereloma, E. V.

    2007-10-01

    The effect of prestraining (PS) and bake hardening (BH) on the microstructures and mechanical properties has been studied in transformation-induced plasticity (TRIP) and dual-phase (DP) steels after intercritical annealing. The DP steel showed an increase in the yield strength and the appearance of the upper and lower yield points after a single BH treatment as compared with the as-received condition, whereas the mechanical properties of the TRIP steel remained unchanged. This difference appears to be because of the formation of plastic deformation zones with high dislocation density around the “as-quenched” martensite in the DP steel, which allowed carbon to pin these dislocations, which, in turn, increased the yield strength. It was found for both steels that the BH behavior depends on the dislocation rearrangement in ferrite with the formation of cell, microbands, and shear band structures after PS. The strain-induced transformation of retained austenite to martensite in the TRIP steel contributes to the formation of a complex dislocation structure.

  4. Thermomechanical deformation behavior of a dynamic strain aging alloy, Hastelloy X

    NASA Technical Reports Server (NTRS)

    Castelli, Michael G.; Miner, Robert V.; Robinson, David N.

    1992-01-01

    An experimental study was performed to identify the effects of dynamic strain aging (solute drag) and metallurgical instabilities under thermomechanical loading conditions. The study involved a series of closely controlled thermomechanical deformation tests on the solid-solution-strenghened nickel-base superalloy, Hastelloy X. This alloy exhibits a strong isothermal strain aging peak at approximately 600 C, promoted by the effects of solute drag and precipitation hardening. Macroscopic thermomechanical hardening trends are correlated with microstructural characteristics through the use of transmission electron microscopy. These observations are compared and contrasted with isothermal conditions. Thermomechanical behavior unique to the isothermal database is identified and discussed. The microstructural characteristics were shown to be dominated by effects associated with the highest temperature of the thermomechanical cycle. Results indicate that the deformation behavior of Hastelloy X is thermomechanically path dependent. In addition, guidance is given pertaining to deformation modeling in the context of macroscopic unified theory. An internal state variable is formulated to qualitatively reflect the isotropic hardening trends identified in the TMD experiments.

  5. Preconsolidation versus aging behavior of kaolinite clay

    SciTech Connect

    Athanasopoulos, G.A. )

    1993-06-01

    Results of resonant column tests were used to determine the effects of overconsolidation ratio (OCR) and of aging on the normalized rate of secondary increase N[sub G] of low-amplitude shear modulus G[sub 0] of a remolded kaolinite clay. The value of N[sub G] decreased approximately linearly with the logarithm of OCR and with the logarithm of duration of aging of the clay. The similarity of behavior provided a basis for establishing an equivalency between age-and-stress-induced equivalent overconsolidation for the clay in question. It was concluded that up to a certain limiting duration of aging the age-induced OCR increases linearly with elapsed time, whereas the effect starts diminishing for longer durations of aging. It is suggested that the results of similar studies on natural clay soils be used for predicting the long-term behavior of clays from the results of short-duration tests.

  6. Ageing behaviour of an Fe-20Ni-1.8Mn-1.6Ti-0.59Al (wt%) maraging alloy: clustering, precipitation and hardening

    SciTech Connect

    Pereloma, E.V. . E-mail: elena.pereloma@spme.monash.edu.au; Shekhter, A.; Miller, M.K.; Ringer, S.P.

    2004-11-08

    Changes in the solute distribution as well as the evolution of precipitation, microstructure and mechanical properties have been studied in an experimental maraging Fe-20Ni-1.8Mn-1.5Ti-0.59Al (wt%) alloy during ageing at 550 deg C. An initial hardening reaction within 5 s is reported, which is remarkable in terms of extent and rapidity. This strengthening was caused by the formation of complex multi-component atomic co-clusters containing primarily Ni-Ti-Al as well as some Mn. This cluster strengthened condition produced the optimum toughness observed throughout the ageing sequence. After 60 s ageing, the appearance of discrete precipitation of needle-shaped {eta}-Ni{sub 3}Ti particles was associated with a second rise in hardness towards an eventual peak at 600 s. This precipitation hardening was accompanied by an increase in tensile strength and a decrease in ductility. A reverse transformation of martensite to austenite occurs progressively during ageing and this contributes to the initial and secondary softening.

  7. An Extended Age-Hardening Model for Al-Mg-Si Alloys Incorporating the Room-Temperature Storage and Cold Deformation Process Stages

    NASA Astrophysics Data System (ADS)

    Myhr, Ole Runar; Grong, Øystein; Schäfer, Carmen

    2015-12-01

    In this article, a new age-hardening model for Al-Mg-Si alloys is presented (named NaMo-Version 2), which takes into account the combined effect of cold deformation and prolonged room-temperature storage on the subsequent response to artificial aging. As a starting point, the original physical framework of NaMo-Version 1 is revived and used as a basis for the extension. This is permissible, since a more in-depth analysis of the underlying particle-dislocation interactions confirms previous expectations that the simplifying assumption of spherical precipitates is not crucial for the final outcome of the calculations, provided that the yield strength model is calibrated against experimental data. At the same time, the implementation of the Kampmann-Wagner formalism means that the different microstructure models can be linked together in a manner that enforces solute partitioning and competition between the different hardening phases which form during aging ( e.g., clusters, β″ and β'). In a calibrated form, NaMo-Version 2 exhibits a high degree of predictive power, as documented by comparison with experiments, using both dedicated nanostructure and yield strength data as a basis for the validation. Hence, the model is deemed to be well-suited for simulation of thermomechanical processing of Al-Mg-Si alloys involving cold-working operations like sheet forming and stretch bending in combination with heat treatment and welding.

  8. Aging behavior and lifetime modeling for polycarbonate

    SciTech Connect

    Kahlen, S.; Wallner, G.M.; Lang, R.W.

    2010-05-15

    In this paper, polycarbonate (PC) as a material candidate for solar absorber applications is investigated as to the aging behavior at different temperatures in air and water. The aging conditioning was performed in air in the temperature range from 120 to 140 C and in water between 70 and 95 C. Tensile tests were performed on unaged and aged PC film specimens at ambient temperature using strain-to-break values as a performance indicator for the degree of aging. For PC the effect of aging was found to strongly depend on the aging conditions. Activation energy based lifetime prediction models according to various methods described in the literature were applied. The activation energies and corresponding lifetime predictions for the temperature range from 40 to 60 C in water and from 90 to 110 C in air derived from these models are compared and interpreted as to their practical relevance. (author)

  9. Radiation and chemical crosslinking promote strain hardening behavior and molecular alignment in ultra high molecular weight polyethylene during multi-axial loading conditions.

    PubMed

    Kurtz, S M; Pruitt, L A; Jewett, C W; Foulds, J R; Edidin, A A

    1999-08-01

    The mechanical behavior and evolution of crystalline morphology during large deformation of eight types of virgin and crosslinked ultra high molecular weight polyethylene (UHMWPE) were studied using the small punch test and transmission electron microscopy (TEM). We investigated the hypothesis that both radiation and chemical crosslinking hinder molecular mobility at large deformations, and hence promote strain hardening and molecular alignment during the multiaxial loading of the small punch test. Chemical crosslinking of UHMWPE was performed using 0.25% dicumyl peroxide (GHR 8110, GUR 1020 and 1050), and radiation crosslinking was performed using 150 kGy of electron beam radiation (GUR 1150). Crosslinking increased the ultimate load at failure and decreased the ultimate displacement of the polyethylenes during the small punch test. Crosslinking also increased the near-ultimate hardening behavior of the polyethylenes. Transmission electron microscopy was used to characterize the crystalline morphology of the bulk material, undeformed regions of the small punch test specimens, and deformed regions of the specimens oriented perpendicular and parallel to the punch direction. In contrast with the virgin polyethylenes, which showed only subtle evidence of lamellar alignment, the crosslinked polyethylenes exhibited enhanced crystalline lamellae orientation after the small punch test, predominantly in the direction parallel to the punch direction or deformation axis. Thus, the results of this study support the hypothesis that crosslinking promotes strain hardening during multiaxial loading because of increased resistance to molecular mobility at large deformations effected by molecular alignment. The data also illustrate the sensitivity of large deformation mechanical behavior and crystalline morphology to the method of crosslinking and resin of polyethylene. PMID:10458558

  10. Comparative Tensile Flow and Work-Hardening Behavior of 9 Pct Chromium Ferritic-Martensitic Steels in the Framework of the Estrin-Mecking Internal-Variable Approach

    NASA Astrophysics Data System (ADS)

    Choudhary, B. K.; Christopher, J.

    2016-06-01

    The comparative tensile flow and work-hardening behavior of P9 steel in two different product forms, normalized and tempered plate and thick section tube plate forging, and P91 steel were investigated in the framework of the dislocation dynamics based Estrin-Mecking (E-M) one-internal-variable approach. The analysis indicated that the flow behavior of P9 and P91 steels was adequately described by the E-M approach in a wide range of temperatures. It was suggested that dislocation dense martensite lath/cell boundaries and precipitates together act as effective barriers to dislocation motion in P9 and P91 steels. At room and intermediate temperatures, the evolution of the internal-state variable, i.e., the dislocation density with plastic strain, exhibited insignificant variations with respect to temperature. At high temperatures, a rapid evolution of dislocation density with plastic strain toward saturation with increasing temperature was observed. The softer P9 steel tube plate forging exhibited higher work hardening in terms of larger gains in the dislocation density and flow stress contribution from dislocations than the P9 steel plate and P91 steel at temperatures ranging from 300 K to 873 K (27 °C to 600 °C). The evaluation of activation energy suggests that the deformation is controlled by cross-slip of dislocations at room and intermediate temperatures, and climb of dislocations at high temperatures. The relative influence of initial microstructure on flow and work-hardening parameters associated with the E-M approach was discussed in the three temperature regimes displayed by P9 and P91 steels.

  11. Yield Behavior of Solution Treated and Aged Ti-6Al-4V

    NASA Technical Reports Server (NTRS)

    Ring, Andrew J.; Baker, Eric H.; Salem, Jonathan A.; Thesken, John C.

    2014-01-01

    Post yield uniaxial tension-compression tests were run on a solution treated and aged (STA), titanium 6-percent aluminum 4-percent vanadium (Ti-6Al-4V) alloy to determine the yield behavior on load reversal. The material exhibits plastic behavior almost immediately on load reversal implying a strong Bauschinger effect. The resultant stress-strain data was compared to a 1D mechanics model and a finite element model used to design a composite overwrapped pressure vessel (COPV). Although the models and experimental data compare well for the initial loading and unloading in the tensile regime, agreement is lost in the compressive regime due to the Bauschinger effect and the assumption of perfect plasticity. The test data presented here are being used to develop more accurate cyclic hardening constitutive models for future finite element design analysis of COPVs.

  12. Dynamic strain aging influence on the cyclic behavior of Zircaloy-4

    SciTech Connect

    Armas, A.F.; Alvarez-Armas, I.; Moscato, G.

    1996-01-15

    Dynamic strain aging is a very important factor in the plastic deformation of zirconium and zirconium alloys and its aspects in uniaxial tensile tests have been the subject of several studies. Evidence of yield points in the stress-strain curve, appearance of plateaus or peaks in the flow stress-temperature diagram, discontinuous plastic flow, abnormal strain rate sensitivity have been reported in the literature. These anomalous mechanical behaviors were observed in these metals within the temperature range 473 to 823 K. The purpose of the present study is to examine the cyclic deformation characteristics of Zircaloy-4 in the temperature range 573--873 K and to show that the abnormal cyclic hardening observed in this material can be considered as a new aspect of dynamic strain aging.

  13. Effect of Strain-Induced Age Hardening on Yield Strength Improvement in Ferrite-Austenite Duplex Lightweight Steels

    NASA Astrophysics Data System (ADS)

    Song, Hyejin; Lee, Seok Gyu; Sohn, Seok Su; Kwak, Jai-Hyun; Lee, Sunghak

    2016-11-01

    Ferrite-austenite lightweight steels showing TRansformation-induced plasticity were developed by varying the aging temperature with or without prestraining, and their effects on tensile properties were investigated in relation with microstructural evolution of carbide formation. The aged steels contained austenite, pearlite, and martensite in the ferrite matrix, and the austenite volume fraction decreased with the increasing aging temperature because some austenite grains decomposed to pearlites. This austenite decomposition to pearlite was favorable for the improvement of yield strength, but negatively influenced overall tensile properties. The prestraining promoted the austenite decomposition by a diffusion-controlled phase transformation, and changed the morphology of the cementite from a long lamellar shape to a densely agglomerated particle shape. In order to obtain the large increase in yield strength as well as excellent combination of strength and ductility, the strain-induced aging treatment, i.e., prestraining followed by aging, is important like in the prestrained and 673 K (400 °C)-aged steel. This large increase in yield strength, in spite of a reduction of elongation (65 to 43 pct), was basically attributed to an appropriate amount of decomposition of austenite to pearlite ( e.g., 4 vol pct), while having sufficient austenite to martensite transformation ( e.g., 14.5 vol pct martensite).

  14. Precipitation Hardening and Statistical Modeling of the Aging Parameters and Alloy Compositions in Al-Cu-Mg-Ag Alloys

    NASA Astrophysics Data System (ADS)

    Al-Obaisi, A. M.; El-Danaf, E. A.; Ragab, A. E.; Soliman, M. S.

    2016-06-01

    The addition of Ag to Al-Cu-Mg systems has been proposed to replace the existing high-strength 2xxx and 7xxx Al alloys. The aged Al-Cu-Mg-Ag alloys exhibited promising properties, due to special type of precipitates named Ω, which cooperate with other precipitates to enhance the mechanical properties significantly. In the present investigation, the effect of changing percentages of alloying elements, aging time, and aging temperature on the hardness values was studied based on a factorial design. According to this design of experiments (DOE)—23 factorial design, eight alloys were cast and hot rolled, where (Cu, Mg, and Ag) were added to aluminum with two different levels for each alloying element. These alloys were aged at different temperatures (160, 190, and 220 °C) over a wide range of time intervals from 10 min. to 64 h. The resulting hardness data were used as an input for Minitab software to model and relate the process variables with hardness through a regression analysis. Modifying the alloying elements' weight percentages to the high level enhanced the hardness of the alloy with about 40% as compared to the alloy containing the low level of all alloying elements. Through analysis of variance (ANOVA), it was figured out that altering the fraction of Cu had the greatest effect on the hardness values with a contribution of about 49%. Also, second-level interaction terms had about 21% of impact on the hardness values. Aging time, quadratic terms, and third-level interaction terms had almost the same level of influence on hardness values (about 10% contribution). Furthermore, the results have shown that small addition of Mg and Ag was enough to improve the mechanical properties of the alloy significantly. The statistical model formulated interpreted about 80% of the variation in hardness values.

  15. Oscillating brittle and viscous behavior through the earthquake cycle in the Red River Shear Zone: Monitoring flips between reaction and textural softening and hardening

    NASA Astrophysics Data System (ADS)

    Wintsch, Robert P.; Yeh, Meng-Wan

    2013-03-01

    Microstructures associated with cataclasites and mylonites in the Red River shear zone in the Diancang Shan block, Yunnan Province, China show evidence for both reaction hardening and softening at lower greenschist facies metamorphic conditions. The earliest fault-rocks derived from Triassic porphyritic orthogneiss protoliths are cataclasites. Brittle fractures and crushed grains are cemented by newly precipitated quartz. These cataclasites are subsequently overprinted by mylonitic fabrics. Truncations and embayments of relic feldspars and biotites show that these protolith minerals have been dissolved and incompletely replaced by muscovite, chlorite, and quartz. Both K-feldspar and plagioclase porphyroclasts are truncated by muscovite alone, suggesting locally metasomatic reactions of the form: 3K-feldspar + 2H+ = muscovite + 6SiO2(aq) + 2K+. Such reactions produce muscovite folia and fish, and quartz bands and ribbons. Muscovite and quartz are much weaker than the reactant feldspars and these reactions result in reaction softening. Moreover, the muscovite tends to align in contiguous bands that constitute textural softening. These mineral and textural modifications occurred at constant temperature and drove the transition from brittle to viscous deformation and the shift in deformation mechanism from cataclasis to dissolution-precipitation and reaction creep. These mylonitic rocks so produced are cut by K-feldspar veins that interrupt the mylonitic fabric. The veins add K-feldspar to the assemblage and these structures constitute both reaction and textural hardening. Finally these veins are boudinaged by continued viscous deformation in the mylonitic matrix, thus defining a late ductile strain event. Together these overprinting textures and microstructures demonstrate several oscillations between brittle and viscous deformation, all at lower greenschist facies conditions where only frictional behavior is predicted by experiments. The overlap of the depths of

  16. Microstructure and aging behavior of conventional and nanocrystalline aluminum-copper-magnesium alloys with scandium additions

    NASA Astrophysics Data System (ADS)

    Zuniga, Alejandro

    The influence of small amounts of scandium (0.15 and 0.3 wt.%) on the microstructure, aging behavior and mechanical properties of 2618 (Al-Cu-Mg-Fe-Ni) and C416 (Al-Cu-Mg-Ag-Mn) alloys was studied. It was observed the overall precipitation sequence and the general morphology of the aging curve were not affected by the addition of small amounts of Sc. It was also observed that a separate population of small Al3Sc particles improved the aging response and mechanical properties of low-Cu, low-Sc Al-Cu-Mg alloys, while the formation of Al5-8Cu7-4Sc particles resulted in a decrease of the mechanical properties in high-Cu Sc-containing alloys. The Sc-modified with the best aging response (2618 + 0.15 % Sc) was cryomilled in order to produce Al-Cu-Mg-Fe-Ni-Sc nanocrystalline powders. Bulk nanocrystalline samples were consolidated from the cryomilled powder using three different techniques: hot isostatic pressing and extrusion, spark plasma sintering, cold spraying. The influence of consolidation technique on the microstructure, aging behavior and mechanical properties was analyzed. The extruded and spark plasma sintered Al-Cu-Mg-Fe-Ni-Sc nanocrystalline samples presented a bimodal grain structure consisting of coarse-grained regions located at the inter-particle region, and nanocrystalline regions at the particle interiors. The aging behavior of the nanocrystalline Al-Cu-Mg-Fe-Ni-Sc alloy was characterized by softening instead of hardening. This behavior was rationalized on the basis of changes in the precipitation processes that occur in the nanocrystalline state. On the other hand, the cold spray process promoted the formation of truly nanocrystalline coatings. The mechanisms influencing the coating formation of conventional and nanocrystalline Al-Cu-Mg-Fe-Ni-Sc samples were analyzed.

  17. Birth Order and Maladaptive Behavior in School-Aged Children.

    ERIC Educational Resources Information Center

    Carmichael, Karla D.

    Drawing on Alfred Adler's theories on the effect of birth order on maladaptive behavior in children, this study focused on the relationship between birth order and the referral to counseling of school-aged children with maladaptive disorder. School-aged children (N=217) with academic or behavioral problems, ages 5 to 18, were referred to the staff…

  18. Solution hardening and strain hardening at elevated temperatures

    SciTech Connect

    Kocks, U.F.

    1982-10-01

    Solutes can significantly increase the rate of strain hardening; as a consequence, the saturation stress, at which strain hardening tends to cease for a given temperature and strain rate, is increased more than the yield stress: this is the major effect of solutes on strength at elevated temperatures, especially in the regime where dynamic strain-aging occurs. It is shown that local solute mobility can affect both the rate of dynamic recovery and the dislocation/dislocation interaction strength. The latter effect leads to multiplicative solution strengthening. It is explained by a new model based on repeated dislocation unlocking, in a high-temperature limit, which also rationalizes the stress dependence of static and dynamic strain-aging, and may help explain the plateau of the yield stress at elevated temperatures. 15 figures.

  19. [Hardening of dental instruments].

    PubMed

    Gerasev, G P

    1981-01-01

    The possibility of prolonging the service life of stomatological instruments by the local hardening of their working parts is discussed. Such hardening should be achieved by using hard and wear-resistant materials. The examples of hardening dental elevators and hard-alloy dental drills are given. New trends in the local hardening of instruments are the treatment of their working parts with laser beams, the application of coating on their surface by the gas-detonation method. The results of research work and trials are presented.

  20. Influence of bismuth on the age-hardening and corrosion behaviour of low-antimony lead alloys in lead/acid battery systems

    NASA Astrophysics Data System (ADS)

    Lam, L. T.; Huynh, T. D.; Haigh, N. P.; Douglas, J. D.; Rand, D. A. J.; Lakshmi, C. S.; Hollingsworth, P. A.; See, J. B.; Manders, J.; Rice, D. M.

    The effects of bismuth additions in the range 0.006-0.086 wt.% on the metallurgical and electrochemical properties of Pb-1.5 wt.% Sb alloy are investigated. The self-discharge behaviour of batteries produced with grids of the doped alloys is also evaluated. Addition of bismuth is found to exert no significant effects on the age-hardening behaviour, general microstructure or grain size of the alloy. It does, however, influence the morphology of the eutectic in the inter-dendritic regions. The latter changes from a mainly lamellar to an irregular type with increasing bismuth content. The corrosion rate of the grid decreases with increase of the bismuth content. Attack occurs preferentially in the inter-dendritic regions where there is an enrichment of both antimony and bismuth. Electron-probe microanalysis shows that the corrosion zone consists of a tri-layered structure, namely: a dense, continuous, inner layer (PbO 1.1); a central layer (PbO 1.8·PbSO 4); a porous outer layer n(PbO 1.8)·PbSO 4, with n=2-8. In the latter, the value of n increases in the direction of corrosive penetration into the grid. Data from atomic absorption spectrometric analysis reveal that bismuth, after oxidative leaching from the grid substrate, is retained mainly in the corrosion layer. A key observation is that bismuth (i.e., up to ˜0.09 wt.%) does not affect the self-discharge behaviour of batteries.

  1. The Developmental Progression of Age 14 Behavioral Disinhibition, Early Age of Sexual Initiation, and Subsequent Sexual Risk-Taking Behavior

    PubMed Central

    Samek, Diana R.; Iacono, William G.; Keyes, Margaret A.; Epstein, Marina; Bornovalova, Marina A.; McGue, Matt

    2013-01-01

    Background Research has demonstrated a consistent relationship between early sexual experience and subsequent sexual risk-taking behaviors. We hypothesized that this relationship is due to a general predisposition towards behavioral disinhibition (BD), and that relationships among BD, early sex, and subsequent risky sexual behavior may be influenced by common genetic influences for males and common environmental influences for females. Methods A prospective sample of 1,512 same-sex adolescent twins (50.2% female) was used. Adolescent BD was measured by clinical symptom counts of conduct disorder, oppositional defiant disorder, and self-reported delinquent behavior (age 14). Age of sexual initiation was defined as first age of consensual oral or penetrative sex (mean age ~17). Adult risky sexual behavior was defined by sexual behaviors under the influence of drugs and alcohol and number of casual sexual partners in the past year (age 24). Results Multivariate analyses showed evidence for substantial common genetic variance among age 14 BD, age at sexual initiation, and adult risky sexual behavior for males, but not females. There was no significant difference in the degree of common environmental influence on these variables for females compared to males. Notably, age of sexual initiation was not significantly correlated with age 24 risky sexual behavior for females. Conclusion The relationship between early sex and later risky sex can be better understood through a general liability towards BD, which is influenced primarily by genetic factors for males. The association between age 14 BD and age of sexual initiation was influenced through a combination of genetic and environmental factors for females; however, age of sexual initiation does not appear to be a salient predictor of adult women’s sexual risk-taking behavior. Findings suggest that prevention programs aimed at reducing sexual risk behavior might target youth exhibiting BD by age 14, particularly males

  2. Behavior management for preschool-aged children.

    PubMed

    Williford, Amanda P; Shelton, Terri L

    2014-10-01

    This article summarizes behavior management strategies for preschool children who are at high risk for attention-deficit/hyperactivity disorder that have found to be effective in improving child behavior. Both parent and teacher training programs are reviewed, as these have been backed by substantial research evidence. In addition, multimodal treatments that include some combination of parent training, teacher training, and social skills training are also reviewed. Interventions emphasize the need for a strong adult-child relationship combined with proactive behavior management strategies to improve child behavior. PMID:25220082

  3. Adulthood Predictors of Health Promoting Behavior in Later Aging

    ERIC Educational Resources Information Center

    Holahan, Carole K.; Suzuki, Rie

    2004-01-01

    This study investigated adulthood predictors of health-promoting behavior in later aging. The participants were 162 members of the Terman Study of the Gifted (Terman et al., 1925), who responded in 1999 at an average age of 86 to a mailout questionnaire which included questions concerning their positive health behavior. Adulthood variables were…

  4. X-ray spectral and timing behavior of Scorpius X-1. Spectral hardening during the flaring branch

    SciTech Connect

    Titarchuk, Lev; Seifina, Elena

    2014-07-10

    We present an analysis of the spectral and timing properties of X-ray emission from the Z-source Sco X-1 during its evolution between the horizontal (HB) and flaring (FB) branches observed with the Rossi X-ray Timing Explorer during the 1996-2002 period. We find that the broadband (3-250 keV) energy spectra during all spectral states can be adequately reproduced by a model, consisting of two Comptonized components and an iron line. We suggest that the seed photons of kT{sub s1} ≲ 0.7 keV coming from the disk and of temperature kT{sub s2} ≲ 1.8 keV coming from the neutron star (NS) are each upscattered by hot electrons of a 'Compton cloud' (hereafter the Comptb1 and Comptb2 components, respectively, which are associated with the similarly subscripted parameters). The photon power-law index Γ{sub 2} is almost constant (Γ{sub 2} ∼ 2) for all spectral states. In turn, Γ{sub 1} demonstrates a two-phase behavior with the spectral state: Γ{sub 1} is quasi-constant at the level Γ{sub 1} ∼ 2 for the HB–NB and Γ{sub 1} is less than 2, namely in the range of 1.3 < Γ{sub 1} < 2, when the source traces the FB. We also detect a decrease kT{sub s2} from 1.8 keV to 0.7 keV during the FB. We interpret this apparent quasi-stability of the indices during the HB–NB in the framework of the model in which the spectrum is determined by the Comptonized thermal components. This effect established for the Comptonized spectral components of the Z-source Sco X-1 is similar to what was previously found in the atoll sources 4U 1728-34, GX 3+1 and 4U 1820-30 and the Z-source GX 340+0 through all spectral states. However, we interpret the index reduction phase detected during the FB in Sco X-1 within the framework of a model in which the spectrum at the FB is determined by high radiation pressure from the NS surface.

  5. X-Ray Spectral and Timing Behavior of Scorpius X-1. Spectral Hardening during the Flaring Branch

    NASA Astrophysics Data System (ADS)

    Titarchuk, Lev; Seifina, Elena; Shrader, Chris

    2014-07-01

    We present an analysis of the spectral and timing properties of X-ray emission from the Z-source Sco X-1 during its evolution between the horizontal (HB) and flaring (FB) branches observed with the Rossi X-ray Timing Explorer during the 1996-2002 period. We find that the broadband (3-250 keV) energy spectra during all spectral states can be adequately reproduced by a model, consisting of two Comptonized components and an iron line. We suggest that the seed photons of kT s1 <~ 0.7 keV coming from the disk and of temperature kT s2 <~ 1.8 keV coming from the neutron star (NS) are each upscattered by hot electrons of a "Compton cloud" (hereafter the Comptb1 and Comptb2 components, respectively, which are associated with the similarly subscripted parameters). The photon power-law index Γ2 is almost constant (Γ2 ~ 2) for all spectral states. In turn, Γ1 demonstrates a two-phase behavior with the spectral state: Γ1 is quasi-constant at the level Γ1 ~ 2 for the HB-NB and Γ1 is less than 2, namely in the range of 1.3 < Γ1 < 2, when the source traces the FB. We also detect a decrease kT s2 from 1.8 keV to 0.7 keV during the FB. We interpret this apparent quasi-stability of the indices during the HB-NB in the framework of the model in which the spectrum is determined by the Comptonized thermal components. This effect established for the Comptonized spectral components of the Z-source Sco X-1 is similar to what was previously found in the atoll sources 4U 1728-34, GX 3+1 and 4U 1820-30 and the Z-source GX 340+0 through all spectral states. However, we interpret the index reduction phase detected during the FB in Sco X-1 within the framework of a model in which the spectrum at the FB is determined by high radiation pressure from the NS surface.

  6. Ethical Behavior in the Information Age

    ERIC Educational Resources Information Center

    Lincoln, Margaret

    2009-01-01

    In the months following AASL's 13th National Conference, the author has begun to process the new learning standards. The invitation to write about ethical behavior, identified as a Common Belief in the learning standards, has enabled her to reflect on how she is coming to grips with this important professional concept in her own practice. Analysis…

  7. Cold Hardening in Citrus Stems

    PubMed Central

    Yelenosky, George

    1975-01-01

    Stem cold hardening developed to different levels in citrus types tested in controlled environments. Exotherms indicated ice spread was more uniform and rapid in unhardened than in cold-hardened stems. All attempts to inhibit the functioning of citrus leaves resulted in less cold hardening in the stems. Citrus leaves contribute a major portion of cold hardening in the wood. PMID:16659340

  8. Age and Employee Green Behaviors: A Meta-Analysis

    PubMed Central

    Wiernik, Brenton M.; Dilchert, Stephan; Ones, Deniz S.

    2016-01-01

    Recent economic and societal developments have led to an increasing emphasis on organizational environmental performance. At the same time, demographic trends are resulting in increasingly aging labor forces in many industrialized nations. Commonly held stereotypes suggest that older workers are less likely to be environmentally responsible than younger workers. To evaluate the degree to which such age differences are present, we meta-analyzed 132 independent correlations and 336 d-values based on 4676 professional workers from 22 samples in 11 countries. Contrary to popular stereotypes, age showed small positive relationships with pro-environmental behaviors, suggesting that older adults engaged in these workplace behaviors slightly more frequently. Relationships with age appeared to be linear for overall, Conserving, Avoiding Harm, and Taking Initiative pro-environmental behaviors, but non-linear trends were observed for Transforming and Influencing Others behaviors. PMID:26973550

  9. Behavior analysis and the study of human aging

    PubMed Central

    Derenne, Adam; Baron, Alan

    2002-01-01

    As the population of older adults continues to rise, psychologists along with other behavioral and social scientists have shown increasing interest in this age group. Although behavior analysts have contributed to research on aging, the focus has been on applications that remedy age-related deficits, rather than a concern with aging as a developmental process. In particular, there has been little interest in the central theoretical questions that have guided gerontologists. How does behavior change with advancing years, and what are the sources of those changes? We consider the possibility that this neglect reflects the long-standing commitment of behavior analysts to variables that can be experimentally manipulated, a requirement that excludes the key variable—age itself. We review the options available to researchers and present strategies that minimize deviations from the traditional features of behavior-analytic designs. Our comments are predicated on the view that aging issues within contemporary society are far too important for behavior analysts to ignore. PMID:22478383

  10. Helium Release Behavior of Aged Titanium Tritides

    SciTech Connect

    SHANAHAN, KIRKL.

    2004-07-27

    One sample of bulk Ti has been loaded with a 50 per cent / 50 per cent deuterium/tritium mixture and statically aged for 6.5 years. Thermal desorption of the sample shows an initial release of hydrogen isotopes followed by 3He release. Subsequent D2 loading/desorption was used to quantify the trapped tritium heel. The sample shows an excess hydrogen capacity as a second thermal desorption peak that partially disappears and shifts with annealing at 923-973K. The main hydrogen desorption peak also shifts to higher temperature, indicating a partial reversal of the tritium-decay induced damage by annealing.

  11. Subjective Age in Early Adolescence: Relationships with Chronological Age, Pubertal Timing, Desired Age, and Problem Behaviors

    ERIC Educational Resources Information Center

    Hubley, Anita M.; Arim, Rubab G.

    2012-01-01

    Subjective age generally refers to the age that one feels. In a cross-sectional questionnaire study of 245 adolescents ages 10-14 years, we examined (a) whether, and when, a cross-over in subjective age occurs, (b) differences in subjective age among pubertal timing groups, (c) correlations between subjective age and each of desired age and five…

  12. Walnuts improve neuronal and behavioral function in aging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction Walnuts are rich in polyunsaturated fatty acids (PUFAs) and polyphenols which have been shown to improve neurochemical and behavioral function. Objectives This study investigated the mechanisms associated with age-related behavioral improvements in rats fed diets supplemented with walnu...

  13. Contribution of β' and β precipitates to hardening in as-solutionized Ag-20Pd-12Au-14.5Cu alloys for dental prosthesis applications.

    PubMed

    Kim, Yonghwan; Niinomi, Mitsuo; Hieda, Junko; Nakai, Masaaki; Cho, Ken; Fukui, Hisao

    2014-04-01

    Dental Ag-20Pd-12Au-14.5Cu alloys exhibit a unique hardening behavior, which the mechanical strengths enhance significantly which enhances the mechanical strength significantly after high-temperature (1123K) solution treatment without aging treatment. The mechanism of the unique hardening is not clear. The contribution of two precipitates (β' and β phases) to the unique hardening behavior in the as-solutionized Ag-20Pd-12Au-14.5Cu alloys was investigated. In addition, the chemical composition of the β' phase was investigated. The fine β' phase densely precipitates in a matrix. The β' phase (semi-coherent precipitate), which causes lattice strain, contributes greatly to the unique hardening behavior. On the other hand, the coarse β phase sparsely precipitates in the matrix. The contribution of the β phase (incoherent precipitate), which does not cause lattice strain, is small. The chemical composition of the β' phase was determined. This study reveals that the fine β' phase precipitated by high-temperature solution treatment leads to the unique hardening behavior in dental Ag-20Pd-12Au-14.5Cu alloys in the viewpoints of the lattice strain contrast and interface coherency. It is expected to make the heat treatment process more practical for hardening. The determined chemical composition of β' phase would be helpful to study an unknown formation process of β' phase.

  14. Age and sexual behavior of Japanese macaques (Macaca fuscata).

    PubMed

    Wolfe, L

    1978-01-01

    The sexual behavior of the Arashiyama West troop, a natural semi-free-ranging troop of Japanese macaques, was studied during the 1973-1974 and 1974-1975 breeding seasons. The troop was transported intact from Japan to its current location in South Texas. There they have been free to move about in a 42.2-hectare electric fence enclosure. This report describes the relationships among age, aging, and sexual behavior. Males beginning at the age of 2.5 years were observed to series-mount estrous females in the double foot clasp mount position. Mounting in series in the double foot position is the normal pattern for Japanese macaque males. The ejaculation of semen with concomitant body movements indicative of orgasm begins at age 4.5 years at the earliest and continues until death. Males 4.5 and 5.5 years of age, sexually mature in the physiological sense, were not consistently sexually mature in the behavioral sense. The oldest male displayed traits that appear analogous to traits observed in aging human males. Females begin to experience estrus at 3.5 years of age. However, like pubescent males, pubescent females display behavioral patterns of sexual immaturity. The oldest female of the troop has remained sexually active. The attainment of sexual maturity by adulthood can be viewed as a learned process leading to efficiency and prowess, followed in old age by sexual involution.

  15. Strain Hardening of Hadfield Manganese Steel

    NASA Astrophysics Data System (ADS)

    Adler, P. H.; Olson, G. B.; Owen, W. S.

    1986-10-01

    The plastic flow behavior of Hadfield manganese steel in uniaxial tension and compression is shown to be greatly influenced by transformation plasticity phenomena. Changes in the stress-strain (σ-ɛ) curves with temperature correlate with the observed extent of deformation twinning, consistent with a softening effect of twinning as a deformation mechanism and a hardening effect of the twinned microstructure. The combined effects give upward curvature to the σ-ɛ curve over extensive ranges of plastic strain. A higher strain hardening in compression compared with tension appears to be consistent with the observed texture development. The composition dependence of stacking fault energy computed using a thermodynamic model suggests that the Hadfield composition is optimum for a maximum rate of deformation twinning. Comparisons of the Hadfield steel with a Co-33Ni alloy exhibiting similar twinning kinetics, and an Fe-21Ni-lC alloy deforming by slip indicate no unusual strain hardening at low strains where deformation is controlled by slip, but an unusual amount of structural hardening associated with the twin formation in the Hadfield steel. A possible mechanism of anomalous twin hardening is discussed in terms of modified twinning behavior (pseudotwinning) in nonrandom solid solutions.

  16. 42. INTERIOR VIEW OF THE NAIL HARDENER USED TO HARDEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    42. INTERIOR VIEW OF THE NAIL HARDENER USED TO HARDEN AND TEMPER THE NAILS; WEST TUBES IN FOREGRPUND AND DRAWBACK TUBE IN THE CENTER - LaBelle Iron Works, Thirtieth & Wood Streets, Wheeling, Ohio County, WV

  17. Aging Behavior and Performance Projections for a Polysulfide Elastomer

    SciTech Connect

    Celina, Mathias C.; Giron, Nicholas Henry; Quintana, Adam

    2015-05-01

    The accelerated aging behavior and aging state of a 30 year old field retrieved polysulfide elastomer was examined. The material is used as an environmental thread sealant for a stainless steel bolt in a steel threaded insert in an aluminum assembly. It is a two component curable polysulfide elastomer that is commercially available in a similar formulation as was applied 30 years ago. The primary goal of this study was to establish if aging over 30 years under moderate aging conditions (mostly ambient temperature and humidity) resulted in significant property changes, or if accelerated aging could identify developing aging pathways which would prevent the extended use of this material. The aging behavior of this material was examined in three ways: A traditional accelerated thermo-oxidative aging study between 95 to 140°C which focused on physical and chemical properties changes, an evaluation of the underlying oxidation rates between RT and 125°C, and an assessment of the aging state of a small 30 year old sample. All three data sets were used to establish aging characteristics, their time evolution, and to extrapolate the observed behavior to predict performance limits at RT. The accelerated aging study revealed a relatively high average activation energy of ~130 kJ/mol which gives overconfident performance predictions. Oxidation rates showed a decreasing behavior with aging time and a lower E a of ~84 kJ/mol from time - temperature superposition , but also predicted sufficient additional performance at RT. Consistent with these projections for extended RT performance, only small changes were observed for the 30 year old material. Extrapolations using this partially aged material also predict ongoing use as a viable option. Unexpected RT degradation could only develop into a concern should the oxidation rate not trend lower over time as was observed at elevated temperature. Considering all data acquired in this limited aging study , there are no immediately

  18. Modeling of Irradiation Hardening of Polycrystalline Materials

    SciTech Connect

    Li, Dongsheng; Zbib, Hussein M.; Garmestani, Hamid; Sun, Xin; Khaleel, Mohammad A.

    2011-09-14

    High energy particle irradiation of structural polycrystalline materials usually produces irradiation hardening and embrittlement. The development of predict capability for the influence of irradiation on mechanical behavior is very important in materials design for next generation reactors. In this work a multiscale approach was implemented to predict irradiation hardening of body centered cubic (bcc) alpha-iron. The effect of defect density, texture and grain boundary was investigated. In the microscale, dislocation dynamics models were used to predict the critical resolved shear stress from the evolution of local dislocation and defects. In the macroscale, a viscoplastic self-consistent model was applied to predict the irradiation hardening in samples with changes in texture and grain boundary. This multiscale modeling can guide performance evaluation of structural materials used in next generation nuclear reactors.

  19. An Anisotropic Hardening Model for Springback Prediction

    NASA Astrophysics Data System (ADS)

    Zeng, Danielle; Xia, Z. Cedric

    2005-08-01

    As more Advanced High-Strength Steels (AHSS) are heavily used for automotive body structures and closures panels, accurate springback prediction for these components becomes more challenging because of their rapid hardening characteristics and ability to sustain even higher stresses. In this paper, a modified Mroz hardening model is proposed to capture realistic Bauschinger effect at reverse loading, such as when material passes through die radii or drawbead during sheet metal forming process. This model accounts for material anisotropic yield surface and nonlinear isotropic/kinematic hardening behavior. Material tension/compression test data are used to accurately represent Bauschinger effect. The effectiveness of the model is demonstrated by comparison of numerical and experimental springback results for a DP600 straight U-channel test.

  20. Effects of long-term thermal aging on the stress corrosion cracking behavior of cast austenitic stainless steels in simulated PWR primary water

    NASA Astrophysics Data System (ADS)

    Li, Shilei; Wang, Yanli; Wang, Hui; Xin, Changsheng; Wang, Xitao

    2016-02-01

    The stress corrosion cracking (SCC) behavior of cast austenitic stainless steels of unaged and thermally aged at 400 °C for as long as 20,000 h were studied by using a slow strain rate testing (SSRT) system. Spinodal decomposition in ferrite during thermal aging leads to hardening in ferrite and embrittlement of the SSRT specimen. Plastic deformation and thermal aging degree have a great influence on the oxidation rate of the studied material in simulated PWR primary water environments. In the SCC regions of the aged SSRT specimen, the surface cracks, formed by the brittle fracture of ferrite phases, are the possible locations for SCC. In the non-SCC regions, brittle fracture of ferrite phases also occurs because of the effect of thermal aging embrittlement.

  1. The influence of stacking fault energy on the mechanical behavior of Cu and Cu-Al alloys: Deformation twinning, work hardening, and dynamic recovery

    NASA Astrophysics Data System (ADS)

    Rohatgi, Aashish; Vecchio, Kenneth S.; Gray, George T.

    2001-01-01

    The role of stacking fault energy (SFE) in deformation twinning and work hardening was systematically studied in Cu (SFE ˜78 ergs/cm2) and a series of Cu-Al solid-solution alloys (0.2, 2, 4, and 6 wt pct Al with SFE ˜75, 25, 13, and 6 ergs/cm2, respectively). The materials were deformed under quasi-static compression and at strain rates of ˜1000/s in a Split-Hopkinson pressure bar (SHPB). The quasi-static flow curves of annealed 0.2 and 2 wt pct Al alloys were found to be representative of solid-solution strengthening and well described by the Hall-Petch relation. The quasi-static flow curves of annealed 4 and 6 wt pct Al alloys showed additional strengthening at strains greater than 0.10. This additional strengthening was attributed to deformation twins and the presence of twins was confirmed by optical microscopy. The strengthening contribution of deformation twins was incorporated in a modified Hall-Petch equation (using intertwin spacing as the “effective” grain size), and the calculated strength was in agreement with the observed quasi-static flow stresses. While the work-hardening rate of the low SFE Cu-Al alloys was found to be independent of the strain rate, the work-hardening rate of Cu and the high SFE Cu-Al alloys (low Al content) increased with increasing strain rate. The different trends in the dependence of work-hardening rate on strain rate was attributed to the difference in the ease of cross-slip (and, hence, the ease of dynamic recovery) in Cu and Cu-Al alloys.

  2. Maternal age at maturation underpins contrasting behavior in offspring

    PubMed Central

    Robertsen, Grethe; Stewart, David C.; McKelvey, Simon; Armstrong, John D.; Metcalfe, Neil B.

    2016-01-01

    In species where parental care occurs primarily via the provisioning of eggs, older females tend to produce larger offspring that have better fitness prospects. Remarkably however, a relationship between age of mother and fitness of offspring has also been reported independently of effects on offspring size suggesting that there may be other factors at play. Here, using experimental matings between wild Atlantic salmon that differed in their age at sexual maturation, we demonstrate distinct size-independent variation in the behavior of their offspring that was related to the maturation age of the mother (but not the father). We found that when juvenile salmon were competing for feeding territories, offspring of early-maturing mothers were more aggressive than those of late-maturing mothers, but were out-competed for food by them. This is the first demonstration of a link between natural variation in parental age at maturation and variation in offspring behavior.

  3. Maternal age at maturation underpins contrasting behavior in offspring

    PubMed Central

    Robertsen, Grethe; Stewart, David C.; McKelvey, Simon; Armstrong, John D.; Metcalfe, Neil B.

    2016-01-01

    In species where parental care occurs primarily via the provisioning of eggs, older females tend to produce larger offspring that have better fitness prospects. Remarkably however, a relationship between age of mother and fitness of offspring has also been reported independently of effects on offspring size suggesting that there may be other factors at play. Here, using experimental matings between wild Atlantic salmon that differed in their age at sexual maturation, we demonstrate distinct size-independent variation in the behavior of their offspring that was related to the maturation age of the mother (but not the father). We found that when juvenile salmon were competing for feeding territories, offspring of early-maturing mothers were more aggressive than those of late-maturing mothers, but were out-competed for food by them. This is the first demonstration of a link between natural variation in parental age at maturation and variation in offspring behavior. PMID:27656083

  4. Prosocial Behavior Increases with Age across Five Economic Games.

    PubMed

    Matsumoto, Yoshie; Yamagishi, Toshio; Li, Yang; Kiyonari, Toko

    2016-01-01

    Ontogenic studies of human prosociality generally agree on that human prosociality increases from early childhood through early adulthood; however, it has not been established if prosociality increases beyond early adulthood. We examined a sample of 408 non-student residents from Tokyo, Japan, who were evenly distributed across age (20-59) and sex. Participants played five economic games each separated by a few months. We demonstrated that prosocial behavior increased with age beyond early adulthood and this effect was shown across all five economic games. A similar, but weaker, age-related trend was found in one of three social value orientation measures of prosocial preferences. We measured participants' belief that manipulating others is a wise strategy for social success, and found that this belief declined with age. Participants' satisfaction with the unilateral exploitation outcome of the prisoner's dilemma games also declined with age. These two factors-satisfaction with the DC outcome in the prisoner's dilemma games and belief in manipulation-mediated the age effect on both attitudinal and behavioral prosociality. Participants' age-related socio-demographic traits such as marriage, having children, and owning a house weakly mediated the age effect on prosociality through their relationships with satisfaction with the DC outcome and belief in manipulation. PMID:27414803

  5. Prosocial Behavior Increases with Age across Five Economic Games

    PubMed Central

    Matsumoto, Yoshie; Yamagishi, Toshio; Li, Yang; Kiyonari, Toko

    2016-01-01

    Ontogenic studies of human prosociality generally agree on that human prosociality increases from early childhood through early adulthood; however, it has not been established if prosociality increases beyond early adulthood. We examined a sample of 408 non-student residents from Tokyo, Japan, who were evenly distributed across age (20–59) and sex. Participants played five economic games each separated by a few months. We demonstrated that prosocial behavior increased with age beyond early adulthood and this effect was shown across all five economic games. A similar, but weaker, age-related trend was found in one of three social value orientation measures of prosocial preferences. We measured participants’ belief that manipulating others is a wise strategy for social success, and found that this belief declined with age. Participants’ satisfaction with the unilateral exploitation outcome of the prisoner’s dilemma games also declined with age. These two factors—satisfaction with the DC outcome in the prisoner’s dilemma games and belief in manipulation—mediated the age effect on both attitudinal and behavioral prosociality. Participants’ age-related socio-demographic traits such as marriage, having children, and owning a house weakly mediated the age effect on prosociality through their relationships with satisfaction with the DC outcome and belief in manipulation. PMID:27414803

  6. X-Ray Diffraction Profile Analysis for Characterizing Isothermal Aging Behavior of M250 Grade Maraging Steel

    NASA Astrophysics Data System (ADS)

    Mahadevan, S.; Jayakumar, T.; Rao, B. P. C.; Kumar, Anish; Rajkumar, K. V.; Raj, Baldev

    2008-08-01

    X-ray diffraction (XRD) studies were carried out to characterize aging behavior of M250 grade maraging steel samples subjected to isothermal aging at 755 K for varying durations of 0.25, 1, 3, 10, 40, 70, and 100 hours. Earlier studies had shown typical features of precipitation hardening, wherein the hardness increased to a peak value due to precipitation of intermetallics and decreased upon further aging (overaging) due to reversion of martensite to austenite. Intermetallic precipitates, while coherent, are expected to increase the microstrain in the matrix. Hence, an attempt has been made in the present study to understand the microstructural changes in these samples using XRD line profile analysis. The anisotropic broadening with diffraction angle observed in the simple Williamson Hall (WH) plot has been addressed using the modified WH (mWH) approach, which takes into account the contrast caused by dislocations on line profiles, leading to new scaling factors in the WH plot. The normalized mean square strain and crystallite size estimated from mWH have been used to infer early precipitation and to characterize aging behavior. The normalized mean square strain has been used to determine the Avrami exponent in the Johnson Mehl Avrami (JMA) equation, which deals with the kinetics of precipitation. The Avrami exponent thus determined has matched well with values found by other methods, as reported in literature.

  7. Privacy and human behavior in the age of information.

    PubMed

    Acquisti, Alessandro; Brandimarte, Laura; Loewenstein, George

    2015-01-30

    This Review summarizes and draws connections between diverse streams of empirical research on privacy behavior. We use three themes to connect insights from social and behavioral sciences: people's uncertainty about the consequences of privacy-related behaviors and their own preferences over those consequences; the context-dependence of people's concern, or lack thereof, about privacy; and the degree to which privacy concerns are malleable—manipulable by commercial and governmental interests. Organizing our discussion by these themes, we offer observations concerning the role of public policy in the protection of privacy in the information age.

  8. [Organic factors in behavior disorders in the developmental age].

    PubMed

    Mitrović, D; Popov, I; Nikolić, V

    1990-01-01

    The problem of bad behavior in the young is as old as the written history of mankind. It is always a current problem in a practical and theoretical sense as well. While everyday life is filled with various forms of criminal offense, drug addiction, the forming of gangs-especially in dynamic societies, theoretical opinions tend to oscillate between biological factors and the psychological-social ones which are always unsuitable for a person in the course of its development. The authors have presented a review of the basic theoretical directions, and after that the results of their own research. Children with behavior disorders were investigated: parallely by psychological-psychiatric investigation as well as with an up-to-date biological approach, examining subclinical semiotics, EEG and REG. On the basis of these comparisons we have come to the following principal opinions: the suggested psycho-neuro-vegetative subclinical syndrome, recommended by the same authors, does not take the behavior disorder upon itself. Also, not every behavior disorder includes the obligatory psycho-neuro-vegetative subclinical syndrome (PNVSS). Nevertheless, PNVSS presents a risk factor for behavior disorder, in the case that the personality in development is growing up under unfavorable psycho-social conditions. Finally, in the younger ages PNVSS, by its primary features, determines the behavior disorder also, while at an older age (after 11) behavior has all the more of an asocial and antisocial character.

  9. Deformation in metals after low temperature irradiation: Part II - Irradiation hardening, strain hardening, and stress ratios

    SciTech Connect

    Byun, Thak Sang; Li, Meimei

    2008-03-01

    Effects of irradiation at temperatures 200oC on tensile stress parameters are analyzed for dozens of bcc, fcc, and hcp pure metals and alloys, focusing on irradiation hardening, strain hardening, and relationships between the true stress parameters. Similar irradiation-hardening rates are observed for all the metals irrespective of crystal type; typically, the irradiation-hardening rates are large, in the range 100 - 1000 GPa/dpa, at the lowest dose of <0.0001 dpa and decrease with dose to a few tens of MPa/dpa or less at about 10 dpa. However, average irradiation-hardening rates over the dose range of 0 dpa − (the dose to plastic instability at yield) are considerably lower for stainless steels due to their high uniform ductility. It is shown that whereas low temperature irradiation increases the yield stress, it does not significantly change the strain-hardening rate of metallic materials; it decreases the fracture stress only when non-ductile failure occurs. Such dose independence in strain hardening behavior results in strong linear relationships between the true stress parameters. Average ratios of plastic instability stress to unirradiated yield stress are about 1.4, 3.9, and 1.3 for bcc metals (and precipitation hardened IN718 alloy), annealed fcc metals (and pure Zr), and Zr-4 alloy, respectively. Ratios of fracture stress to plastic instability stress are calculated to be 2.2, 1.7, and 2.1, respectively. Comparison of these values confirms that the annealed fcc metals and other soft metals have larger uniform ductility but smaller necking ductility when compared to other materials.

  10. Circadian arrhythmia dysregulates emotional behaviors in aged Siberian hamsters

    PubMed Central

    Prendergast, Brian J.; Onishi, Kenneth G.; Patel, Priyesh N.; Stevenson, Tyler J.

    2014-01-01

    Emotional behaviors are influenced by the circadian timing system. Circadian disruptions are associated with depressive-like symptoms in clinical and preclinical populations. Circadian rhythm robustness declines markedly with aging and may contribute to susceptibility to emotional dysregulation in aged individuals. The present experiments used a model of chronic circadian arrhythmia generated noninvasively, via a series of circadian-disruptive light treatments, to investigate interactions between circadian desynchrony and aging on depressive- and anxiety-like behaviors, and on limbic neuroinflammatory gene expression that has been linked with emotionality. We also examined whether a social manipulation (group housing) would attenuate effects of arrhythmia on emotionality. In aged (14-18 months of age) male Siberian hamsters, circadian arrhythmia increased behavioral despair and decreased social motivation, but decreased exploratory anxiety. These effects were not evident in younger (5-9 months of age) hamsters. Social housing (3-5 hamsters/cage) abolished the effects of circadian arrhythmia on emotionality. Circadian arrhythmia alone was without effect on hippocampal or cortical interleukin-1β (IL-1β) and indoleamine 2,3-dioxygenase (Ido) mRNA expression in aged hamsters, but social housing decreased hippocampal IL-1β and Ido mRNAs. The data demonstrate that circadian disruption can negatively impact affective state, and that this effect is pronounced in older individuals. Although clear associations between circadian arrhythmia and constitutive limbic proinflammatory activity were not evident, the present data suggest that social housing markedly inhibits constitutive hippocampal IL-1β and Ido activity, which may contribute to the ameliorating effects of social housing on a number of emotional behaviors. PMID:24333374

  11. Circadian arrhythmia dysregulates emotional behaviors in aged Siberian hamsters.

    PubMed

    Prendergast, Brian J; Onishi, Kenneth G; Patel, Priyesh N; Stevenson, Tyler J

    2014-03-15

    Emotional behaviors are influenced by the circadian timing system. Circadian disruptions are associated with depressive-like symptoms in clinical and preclinical populations. Circadian rhythm robustness declines markedly with aging and may contribute to susceptibility to emotional dysregulation in aged individuals. The present experiments used a model of chronic circadian arrhythmia generated noninvasively, via a series of circadian-disruptive light treatments, to investigate interactions between circadian desynchrony and aging on depressive- and anxiety-like behaviors, and on limbic neuroinflammatory gene expression that has been linked with emotionality. We also examined whether a social manipulation (group housing) would attenuate effects of arrhythmia on emotionality. In aged (14-18 months of age) male Siberian hamsters, circadian arrhythmia increased behavioral despair and decreased social motivation, but decreased exploratory anxiety. These effects were not evident in younger (5-9 months of age) hamsters. Social housing (3-5 hamsters/cage) abolished the effects of circadian arrhythmia on emotionality. Circadian arrhythmia alone was without effect on hippocampal or cortical interleukin-1β (IL-1β) and indoleamine 2,3-dioxygenase (Ido) mRNA expression in aged hamsters, but social housing decreased hippocampal IL-1β and Ido mRNAs. The data demonstrate that circadian disruption can negatively impact affective state, and that this effect is pronounced in older individuals. Although clear associations between circadian arrhythmia and constitutive limbic proinflammatory activity were not evident, the present data suggest that social housing markedly inhibits constitutive hippocampal IL-1β and Ido activity, which may contribute to the ameliorating effects of social housing on a number of emotional behaviors.

  12. Effects of aging on the mechanical behavior of human dentin.

    PubMed

    Arola, D; Reprogel, R K

    2005-06-01

    An experimental study on the mechanical behavior of human dentin and the influence of age was conducted. Beams with rectangular cross-section were sectioned from the coronal dentin of virgin extracted molars (N = 76) that were obtained from (N = 70) patients between 17 and 80 years of age. The beams were loaded in either quasi-static 4-point flexure or 4-point flexural fatigue to failure and the stiffness, strength and fatigue properties were evaluated. In characterizing the fatigue response the beams were divided into two age groups that were regarded as young (17 < or = age < or = 30, mean +/- std. dev. = 25 +/- 5 years) and old (50 < or = age < or = 80, mean +/- std. dev. = 64 +/- 9 years) dentin. Results from monotonic loading showed that both the flexural strength and strain to fracture of dentin decreased significantly with age. The fatigue life of dentin increased with a reduction in cyclic stress amplitude and the fatigue strength of young dentin was greater than that of old dentin at all cyclic stress amplitudes. The endurance strength of young dentin (at 10(7) cycles) was approximately 44 MPa, whereas the old dentin exhibited an endurance strength of approximately 23 MPa. Based on differences in the mechanical behavior and microscopic features of the fracture surfaces from the young and old specimens, aging appears to result in an increase in both the rate of damage initiation and propagation in dentin.

  13. Reward components of feeding behavior are preserved during mouse aging

    PubMed Central

    Harb, Mazen R.; Sousa, Nuno; Zihl, Joseph; Almeida, Osborne F. X.

    2014-01-01

    Eating behavior depends on associations between the sensory and energetic properties of foods. Healthful balance of these factors is a challenge for industrialized societies that have an abundance of food, food choices and food-related cues. Here, we were interested in whether appetitive conditioning changes as a function of age. Operant and pavlovian conditioning experiments (rewarding stimulus was a palatable food) in male mice (aged 3, 6, and 15 months) showed that implicit (non-declarative) memory remains intact during aging. Two other essential components of eating behavior, motivation and hedonic preference for rewarding foods, were also found not to be altered in aging mice. Specifically, hedonic responding by satiated mice to isocaloric foods of differing sensory properties (sucrose, milk) was similar in all age groups; importantly, however, this paradigm disclosed that older animals adjust their energy intake according to energetic need. Based on the assumption that the mechanisms that control feeding are conserved across species, it would appear that overeating and obesity in humans reflects a mismatch between ancient physiological mechanisms and today's cue-laden environment. The implication of the present results showing that aging does not impair the ability to learn stimulus-food associations is that the risk of overeating in response to food cues is maintained through to old age. PMID:25278876

  14. Gender, Age, and Behavior Differences in Early Adolescent Worry

    ERIC Educational Resources Information Center

    Brown, Stephen L.; Teufel, James A.; Birch, David A.; Kancherla, Vijaya

    2006-01-01

    Early adolescents in the United States are increasingly exposed to a culture of worrisome messages. A degree of adolescent worry is normal, but the likelihood of a young person being anxious or depressed increases with the perceived number of worries. This study examined the effect of age, gender, and worry behavior on frequency of 8 adolescent…

  15. Age sensitivity of behavioral tests and brain substrates of normal aging in mice.

    PubMed

    Kennard, John A; Woodruff-Pak, Diana S

    2011-01-01

    Knowledge of age sensitivity, the capacity of a behavioral test to reliably detect age-related changes, has utility in the design of experiments to elucidate processes of normal aging. We review the application of these tests in studies of normal aging and compare and contrast the age sensitivity of the Barnes maze, eyeblink classical conditioning, fear conditioning, Morris water maze, and rotorod. These tests have all been implemented to assess normal age-related changes in learning and memory in rodents, which generalize in many cases to age-related changes in learning and memory in all mammals, including humans. Behavioral assessments are a valuable means to measure functional outcomes of neuroscientific studies of aging. Highlighted in this review are the attributes and limitations of these measures in mice in the context of age sensitivity and processes of brain aging. Attributes of these tests include reliability and validity as assessments of learning and memory, well-defined neural substrates, and sensitivity to neural and pharmacological manipulations and disruptions. These tests engage the hippocampus and/or the cerebellum, two structures centrally involved in learning and memory that undergo functional and anatomical changes in normal aging. A test that is less well represented in studies of normal aging, the context pre-exposure facilitation effect (CPFE) in fear conditioning, is described as a method to increase sensitivity of contextual fear conditioning to changes in the hippocampus. Recommendations for increasing the age sensitivity of all measures of normal aging in mice are included, as well as a discussion of the potential of the under-studied CPFE to advance understanding of subtle hippocampus-mediated phenomena.

  16. Precipitation hardening austenitic superalloys

    DOEpatents

    Korenko, Michael K.

    1985-01-01

    Precipitation hardening, austenitic type superalloys are described. These alloys contain 0.5 to 1.5 weight percent silicon in combination with about 0.05 to 0.5 weight percent of a post irradiation ductility enhancing agent selected from the group of hafnium, yttrium, lanthanum and scandium, alone or in combination with each other. In addition, when hafnium or yttrium are selected, reductions in irradiation induced swelling have been noted.

  17. RHOBOT: Radiation hardened robotics

    SciTech Connect

    Bennett, P.C.; Posey, L.D.

    1997-10-01

    A survey of robotic applications in radioactive environments has been conducted, and analysis of robotic system components and their response to the varying types and strengths of radiation has been completed. Two specific robotic systems for accident recovery and nuclear fuel movement have been analyzed in detail for radiation hardness. Finally, a general design approach for radiation-hardened robotics systems has been developed and is presented. This report completes this project which was funded under the Laboratory Directed Research and Development program.

  18. Respiratory and sniffing behaviors throughout adulthood and aging in mice

    PubMed Central

    Wesson, Daniel W.; Varga-Wesson, Adrienn G.; Borkowski, Anne H.; Wilson, Donald A.

    2011-01-01

    Orienting responses are physiological and active behavioral reactions evoked by novel stimulus perception and are critical for survival. We explored whether odor orienting responses are impacted throughout both adulthood and normal and pathological aging in mice. Novel odor investigation (including duration and bout numbers) and its subsequent habituation as assayed in the odor habituation task were preserved in adult C57BL/6J mice up to 12mo of age with <6% variability between age groups in investigation time. Separately, using whole-body plethysmography we found that both spontaneous respiration and odor-evoked sniffing behaviors were strikingly preserved in wildtype (WT) mice up to 26mo of age. In contrast, mice accumulating amyloid-β protein in the brain by means of overexpressing mutations in the human amyloid precursor protein gene (APP) showed preserved spontaneous respiration up to 12mo, but starting at 14mo showed significant differences from WT. Similar to WTs, odor-evoked sniffing was not impacted in APP mice up to 26mo. These results show that odor-orienting responses are minimally impacted throughout aging in mice, and suggest that the olfactomotor network is mostly spared of insults due to aging. PMID:21524667

  19. Nuclear effects hardened shelters

    NASA Astrophysics Data System (ADS)

    Lindke, Paul

    1990-11-01

    The Houston Fearless 76 Government Projects Group has been actively engaged for more than twenty-five years as a sub-contractor and currently as a prime contractor in the design, manufacture, repair and logistics support of custom mobile ground stations and their equipment accommodations. Other associated products include environmental control units (ECU's), mobilizers for shelters and a variety of mobile power generation units (MPU's). Since 1984, Houston Fearless 76 has designed and manufactured four 8' x 8' x 22' nuclear hardened mobile shelters. These shelters were designed to contain electronic data processing/reduction equipment. One shelter is currently being operated by the Air Force as a Defense Intelligence Agency (DIA) approved and certified Special Corrpartmented Information Facility (SCIF). During the development and manufacturing process of the shelters, we received continual technical assistance and design concept evaluations from Science Applications International Corporation (SAIC) Operations Analysis and Logistics Engineering Division and the Nondestructive Inspection Lab at McClellan AFB. SAIC was originally employed by the Air Force to design the nuclear hardening specifications applied to these shelters. The specific levels of hardening to which the shelters were designed are classified and will not be mentioned during this presentation.

  20. Age differences in the impact of employment on antisocial behavior.

    PubMed

    Monahan, Kathryn C; Steinberg, Laurence; Cauffman, Elizabeth

    2013-01-01

    While research suggests that working more than 20 hr weekly is associated with greater antisocial behavior among middle- and upper-class youth, some have argued that employment benefits at-risk youth and leads to desistance from crime among youthful offenders. This study investigates the relation between hours worked, school attendance, and employment characteristics on antisocial behavior in a sample of approximately 1,300 juvenile offenders (ages 14-17 at baseline) tracked over 5 years. The combinations of high-intensity employment and irregular school attendance, unemployment and irregular school attendance, and unemployment and not being enrolled in school are associated with significantly greater antisocial behavior, particularly during early adolescence. High-intensity employment diminishes antisocial behavior only when accompanied by attending school. PMID:23278700

  1. Young Girls’ and Caretakers’ Reports of Problem Behavior: Comprehension and Concordance Across Age, Race, and Behavior

    PubMed Central

    Slocum, Lee Ann; Simpson, Sally S.; Hipwell, Alison E.; Loeber, Rolf

    2012-01-01

    The article discusses a research instrument developed and utilized by the Pittsburgh Girls Study that asked young girls (ages 7 and 8) and their caretakers to report on the girls’ involvement in a variety of problem behaviors. In this article, the authors evaluate whether comprehension, prevalence, and caretaker–child concordance of problem behaviors varied by child age and race. Results indicate that the girls understood most questions (except for some related to drug use) and that comprehension and reported involvement increased with age. Findings show that nonwhites showed greater comprehension and reported more involvement in problem behavior than Whites. Overall, the authors find modest concordance between reports from the girls and their caretakers, with greater agreement for nonwhites and older children. The authors conclude that a more comprehensive understanding of youth problem behavior is gained when both caretakers and children provide reports. PMID:22457546

  2. Behavioral Assessment of the Aging Mouse Vestibular System

    PubMed Central

    Tung, Victoria W. K.; Burton, Thomas J.; Dababneh, Edward; Quail, Stephanie L.; Camp, Aaron J.

    2014-01-01

    Age related decline in balance performance is associated with deteriorating muscle strength, motor coordination and vestibular function. While a number of studies show changes in balance phenotype with age in rodents, very few isolate the vestibular contribution to balance under either normal conditions or during senescence. We use two standard behavioral tests to characterize the balance performance of mice at defined age points over the lifespan: the rotarod test and the inclined balance beam test. Importantly though, a custom built rotator is also used to stimulate the vestibular system of mice (without inducing overt signs of motion sickness). These two tests have been used to show that changes in vestibular mediated-balance performance are present over the murine lifespan. Preliminary results show that both the rotarod test and the modified balance beam test can be used to identify changes in balance performance during aging as an alternative to more difficult and invasive techniques such as vestibulo-ocular (VOR) measurements. PMID:25045963

  3. Effect of micro-structural modifier on the morphology of silicon rich secondary phase and strain hardening behavior of eutectic Al-Si alloy

    NASA Astrophysics Data System (ADS)

    Mansoor, M.; Salam, I.; Tauqir, A.

    2016-08-01

    Eutectic Al-Si alloys find their applications in moderate to severe tribological conditions, for example: pistons, casings of high speed pumps and slide sleeves. The higher hardness, so the better tribological properties, are originated by the formation of a silicon rich secondary phase, however, the morphology of the secondary phase drastically influence the toughness of the alloy. Microstructural modifiers are used to control the toughness which modifies the Si rich secondary phase into dispersed spherical structure instead of needle-like network. In the present study, a mixture of chemical fluxes was used to modify the Si phase. The alloy was cast into a sand mold and characterized by scanning electron microscopy, energy dispersive spectroscopy, hardness testing and tensile testing. It was found that the morphology of the Si phase was altered to acicular structure due to the modification process. In comparison, the un-modified alloy contained Si phase in needle-like structure. The effect of modifier was also pronounced on the mechanical properties, where increase of 50% in yield strength, 56% in tensile strength and 200% in elongation occurred. A discernable raise in strain hardening component indicated the improved strain harden ability and formability of the modified alloy.

  4. Age-Related Changes in Demand–Withdraw Communication Behaviors

    PubMed Central

    Holley, Sarah R.; Haase, Claudia M.; Levenson, Robert W.

    2013-01-01

    Demand–withdraw communication is a set of conflict-related behaviors in which one partner blames or pressures while the other partner withdraws or avoids. The present study examined age-related changes in these behaviors longitudinally over the course of later life stages. One hundred twenty-seven middle-aged and older long-term married couples were observed at 3 time points across 13 years as they engaged in a conversation about an area of relationship conflict. Husbands’ and wives’ demand–withdraw behaviors (i.e., blame, pressure, withdrawal, avoidance) were objectively rated by trained coders at each time point. Data were analyzed using dyad-level latent growth curve models in a structural equation modeling framework. For both husbands and wives, the results showed a longitudinal pattern of increasing avoidance behavior over time and stability in all other demand and withdraw behaviors. This study supports the notion that there is an important developmental shift in the way that conflict is handled in later life. PMID:23913982

  5. Grain boundary hardening and triple junction hardening in polycrystalline molybdenum

    SciTech Connect

    Kobayashi, Shigeaki . E-mail: skoba@ashitech.ac.jp; Tsurekawa, Sadahiro; Watanabe, Tadao

    2005-02-01

    The grain boundary and triple junction hardenings in molybdenum with different carbon content were studied in connection with the character and the connectivity of grain boundaries at triple junctions by the micro-indentation test. The triple junction hardening is smaller at the junctions composed of low-angle and {sigma} boundaries than at the junctions composed of random boundaries. This difference in the hardening depending on the grain boundary connectivity becomes more significant with a decrease in carbon content in molybdenum.

  6. Strain Hardening and Size Effect in Five-fold Twinned Ag Nanowires.

    PubMed

    Narayanan, Sankar; Cheng, Guangming; Zeng, Zhi; Zhu, Yong; Zhu, Ting

    2015-06-10

    Metallic nanowires usually exhibit ultrahigh strength but low tensile ductility owing to their limited strain hardening capability. Here we study the unique strain hardening behavior of the five-fold twinned Ag nanowires by nanomechanical testing and atomistic modeling. In situ tensile tests within a scanning electron microscope revealed strong strain hardening behavior of the five-fold twinned Ag nanowires. Molecular dynamics simulations showed that such strain hardening was critically controlled by twin boundaries and pre-existing defects. Strain hardening was size dependent; thinner nanowires achieved more hardening and higher ductility. The size-dependent strain hardening was found to be caused by the obstruction of surface-nucleated dislocations by twin boundaries. Our work provides mechanistic insights into enhancing the tensile ductility of metallic nanostructures by engineering the internal interfaces and defects.

  7. Altruistic organizational citizenship behavior: context, disposition, and age.

    PubMed

    Wagner, S L; Rush, M C

    2000-06-01

    The authors proposed employee age as moderating the structural stability of altruistic organizational citizenship behavior (OCB) with regard to the influence of context-relevant attitudes and dispositional variables. Analyses of peer ratings of altruistic OCB in a sample of 96 U.S. nurses showed that the contextual variables of job satisfaction, organizational commitment, and trust in management were germane for the younger participants. The dispositional variable of moral judgment was a unique predictor of altruistic OCB among the older participants.

  8. Aging does not influence feeding behavior in cats.

    PubMed

    Peachey, Sarah E; Harper, E Jean

    2002-06-01

    The aim of this investigation was to see whether aging influences feeding behavior in cats. Two studies were carried out. In the first study, a standard canned cat food was fed to six young adult and six senior cats for 10 d on an ad libitum basis. Feeding behavior was monitored during the final 5 d. In the second study, diets enriched with beef tallow, olive oil or sunflower oil were fed at an equivalent energy intake for 21 d. Feeding behavior was monitored during the final 5 d. The results of both studies indicated no significant differences between the young and old cats in the number of meals consumed, the amount consumed at each meal or the duration of each meal when fed either ad libitum or at equivalent energy intakes. Daily feeding patterns were similar for each of the 5 d for each cat, with cats tending to consume regular small meals throughout the day and night. The only significant differences noted were among the fat-enriched diets. The diet enriched with beef tallow had fewer refusals compared to the diets enriched with olive oil and sunflower oil, indicating a possible palatability differential. It was concluded that cats of all ages are habitual feeders with similar daily feeding patterns, which may be altered only with a change in diet. Given that no differences were seen between the young and senior cats, it cannot be assumed that feeding patterns are responsible for the previously observed age-related decreases in apparent digestibility. PMID:12042511

  9. Cosleeping and sleep behavior in Italian school-aged children.

    PubMed

    Cortesi, Flavia; Giannotti, Flavia; Sebastiani, Teresa; Vagnoni, Cristina

    2004-02-01

    The prevalence and predictors of cosleeping were investigated in 901 healthy school-aged children. Parent reports on the Children's Sleep Habits Questionnaire and Child Behavior Checklist were used to assess children's sleep and behavioral problems. Regular, long-lasting cosleeping was present in 5% of our sample. Cosleepers rated higher on the Children's Sleep Habits Questionnaire total score and Bedtime Resistance, Sleep Anxiety, Nightwakings, and Parasomnias subscales than solitary sleepers. No significant behavioral problems were found in cosleepers. Regression results showed that low socioeconomic status, one parent who is a shiftworker, one-parent families, one parent who coslept as a child, prolonged breastfeeding, and previous and current sleep problems significantly predicted cosleeping. The high incidence of parents reporting having coslept as a child also suggested a lifestyle choice. Thus, cosleeping seems to reflect a parent's way to cope with sleep problems, and the long persistence of this practice may be related to the lifestyle of families.

  10. Behavior Management for School Aged Children with ADHD

    PubMed Central

    Pfiffner, Linda J.; Haack, Lauren M.

    2014-01-01

    Synopsis Behavior management treatments are the most commonly used nonpharmacological approaches for treating ADHD and associated impairments. This review focuses on behavioral parent training interventions for school age children in the home setting and adjunctive treatments developed to extend effects across settings. The underlying theoretical basis and content of these interventions are described. Empirical support includes numerous randomized clinical trials, systematic reviews, and meta-analyses showing positive effects of these interventions on child compliance, ADHD symptoms and impairments, parent-child interactions, parenting and parenting stress. These studies support categorization of behavior management treatment as a well-established, evidence-based treatment for ADHD. Factors for consideration in clinical decision-making and future directions for research are provided. PMID:25220083

  11. From the reaching behavior at 5 months of age to hand preference at preschool age.

    PubMed

    Marschik, Peter B; Einspieler, Christa; Strohmeier, Andrea; Plienegger, Johann; Garzarolli, Bettina; Prechtl, Heinz F R

    2008-07-01

    The aim of the study was to examine the reaching behavior at the age of 5 months, and to determine whether and to what extent there is a relationship between hand use at this age and manual laterality at preschool age. 20 participants (13 girls and 7 boys) were investigated on two occasions: At the age of 5 months we assessed the hand use for reaching for four different objects placed at the infant's body midline or in their right or left hemispaces, respectively. At the age of 5 years and 7 months, we assessed the hand use for 22 motor tasks. The handedness status was calculated in order to reflect the sinistrality-dextrality continuum. All but one infant were unimanual reachers at 5 months of age. Preferential reaching was space dependent rather than object dependent at this stage. Children reaching for objects in the right hemispace predominantly with their right hand showed a significantly greater right hand laterality at late preschool age than children who at the age of 5 months had shown inconsistent hand use (p < .05). Children who at the age of 5 months had reached for objects in the left hemispace with their left hand proved to be less lateralized in their right hand use approximately 5 years later (p < .05).

  12. Practical aspects of systems hardening

    SciTech Connect

    Shepherd, W.J.

    1989-01-01

    Applications of hardening technology in a practical system require a balance between the factors governing affordability, producibility, and survivability of the finished design. Without careful consideration of the top-level system operating constraints, a design engineer may find himself with a survivable but overweight, unproductive, expensive design. This paper explores some lessons learned in applying hardening techniques to several laser communications programs and is intended as an introductory guide to novice designers faced with the task of hardening a space system.

  13. Induction Hardening vs Conventional Hardening of a Heat Treatable Steel

    NASA Astrophysics Data System (ADS)

    Sackl, Stephanie; Leitner, Harald; Zuber, Michael; Clemens, Helmut; Primig, Sophie

    2014-11-01

    This study focuses on the comparison of mechanical and microstructural properties of induction and conventionally heat-treated steels in the as-quenched state. The investigated steel is a heat treatable 42CrMo4 steel. In order to characterize the mechanical properties, tensile tests and Vickers hardness tests are performed. The yield strength and hardness of the induction hardened condition turn out to be slightly lower compared to the conventionally hardened one. Light optical and scanning electron microscopy show no differences in the martensitic structure of the induction and conventionally hardened condition. However, electron back scatter diffraction investigations reveal a smaller block size within the conventionally hardened specimen. Carbon mappings by electron probe micro analysis show a homogenous carbon concentration in the conventionally hardened and a non-uniform distribution in the induction-hardened case. The segregation of the carbon exhibits line-type features in the induction hardened condition, lowering the total amount of carbon in the matrix. Therefore, the carbon content in the matrix of the conventionally hardened condition is slightly higher, which causes a smaller block size. The smaller block size is believed to be the reason for the higher hardness and yield strength.

  14. The relationship between microstructure and age hardening response in the metastable beta titanium alloy Ti- 11.5 Mo-6 Zr-4.5 Sn (beta III)

    NASA Astrophysics Data System (ADS)

    Froes, F. H.; Yolton, C. F.; Capenos, J. M.; Wells, M. G. H.; Williams, J. C.

    1980-12-01

    The influence of heat treatment and oxygen content on the aging response and micro-structure of the metastable Β-phase titanium alloy Ti-11.5Mo-6Zr-4.5Sn (Beta III) has been studied using light and electron metallography and hardness measurements. Increasing the oxygen from 0.17 to 0.28 wt pet was shown to suppress Ω-phase formation and accelerate a-phase formation. Changing the solution treatment from above to below the Β-transus was shown to significantly increase the rate of α-phase formation at residual dislocations and subboundaries present in the warm worked material. Direct aging has been shown to greatly retard the rate of Ω-phase formation by comparison to quenching and aging. Duplex aging first at a temperature in the Ω-phase formation range and then at a temperature in the a-phase formation range results in a very fine dispersion of α-phase particles and a very high hardness. It is suggested that this α-phase forms by an insitu Ω → α transformation. In quenched samples small amounts (10 pct) of cold work were shown to accelerate the formation of Ω-phase during subsequent aging as shown by both electron microscopy and by hardness measurements. Finally, some remarks are included to indicate the application of our observations to the commercial heat treatment of Β-III.

  15. Young Girls' and Caretakers' Reports of Problem Behavior: Comprehension and Concordance across Age, Race, and Behavior

    ERIC Educational Resources Information Center

    Slocum, Lee Ann; Simpson, Sally S.; Hipwell, Alison E.; Loeber, Rolf

    2011-01-01

    The article discusses a research instrument developed and utilized by the Pittsburgh Girls Study that asked young girls (ages 7 and 8) and their caretakers to report on the girls' involvement in a variety of problem behaviors. In this article, the authors evaluate whether comprehension, prevalence, and caretaker-child concordance of problem…

  16. Method and apparatus for welding precipitation hardenable materials

    DOEpatents

    Murray, Jr., Holt; Harris, Ian D.; Ratka, John O.; Spiegelberg, William D.

    1994-01-01

    A method for welding together members consisting of precipitation age hardened materials includes the steps of selecting a weld filler material that has substantially the same composition as the materials being joined, and an age hardening characteristic temperature age threshold below that of the aging kinetic temperature range of the materials being joined, whereby after welding the members together, the resulting weld and heat affected zone (HAZ) are heat treated at a temperature below that of the kinetic temperature range of the materials joined, for obtaining substantially the same mechanical characteristics for the weld and HAZ, as for the parent material of the members joined.

  17. Method and apparatus for welding precipitation hardenable materials

    DOEpatents

    Murray, H. Jr.; Harris, I.D.; Ratka, J.O.; Spiegelberg, W.D.

    1994-06-28

    A method for welding together members consisting of precipitation age hardened materials includes the steps of selecting a weld filler material that has substantially the same composition as the materials being joined, and an age hardening characteristic temperature age threshold below that of the aging kinetic temperature range of the materials being joined, whereby after welding the members together, the resulting weld and heat affected zone (HAZ) are heat treated at a temperature below that of the kinetic temperature range of the materials joined, for obtaining substantially the same mechanical characteristics for the weld and HAZ, as for the parent material of the members joined. 5 figures.

  18. Behavioral risk factor surveillance of aged Medicare beneficiaries, 1995.

    PubMed

    Arday, D R; Arday, S L; Bolen, J; Rhodes, L; Chin, J; Minor, P

    1997-01-01

    The Behavioral Risk Factor Surveillance System (BRFSS) is an ongoing State-based telephone survey of adults, administered through State health departments. The survey estimates health status and the prevalence of various risk factors among respondents, who include both fee-for-service and managed care Medicare beneficiaries. In this article the authors present an overview of the BRFSS and report 1995 regional results among respondents who were 65 years of age or over and who had health insurance. The advantages and disadvantages of using the BRFSS as a tool to monitor beneficiary health status and risk factors are also discussed.

  19. General analytical shakedown solution for structures with kinematic hardening materials

    NASA Astrophysics Data System (ADS)

    Guo, Baofeng; Zou, Zongyuan; Jin, Miao

    2016-04-01

    The effect of kinematic hardening behavior on the shakedown behaviors of structure has been investigated by performing shakedown analysis for some specific problems. The results obtained only show that the shakedown limit loads of structures with kinematic hardening model are larger than or equal to those with perfectly plastic model of the same initial yield stress. To further investigate the rules governing the different shakedown behaviors of kinematic hardening structures, the extended shakedown theorem for limited kinematic hardening is applied, the shakedown condition is then proposed, and a general analytical solution for the structural shakedown limit load is thus derived. The analytical shakedown limit loads for fully reversed cyclic loading and non-fully reversed cyclic loading are then given based on the general solution. The resulting analytical solution is applied to some specific problems: a hollow specimen subjected to tension and torsion, a flanged pipe subjected to pressure and axial force and a square plate with small central hole subjected to biaxial tension. The results obtained are compared with those in literatures, they are consistent with each other. Based on the resulting general analytical solution, rules governing the general effects of kinematic hardening behavior on the shakedown behavior of structure are clearly.

  20. Intensive Behavioral Intervention for School-Aged Children with Autism: Una Breccia nel Muro (UBM)--A Comprehensive Behavioral Model

    ERIC Educational Resources Information Center

    Fava, Leonardo; Vicari, Stefano; Valeri, Giovanni; D'Elia, Lidia; Arima, Serena; Strauss, Kristin

    2012-01-01

    Although, reviews and outcome research supports empirical evidence for Early Intensive Behavior Intervention in pre-scholars, intensive behavioral service provision for school-aged children with autism spectrum disorders (ASD) are less subject to research studies. In order to provide effective behavioral interventions for school-aged children it…

  1. Reproduction, social behavior, and aging trajectories in honeybee workers.

    PubMed

    Dixon, Luke; Kuster, Ryan; Rueppell, Olav

    2014-02-01

    While a negative correlation between reproduction and life span is commonly observed, specialized reproductive individuals outlive their non-reproductive nestmates in all eusocial species, including the honeybee, Apis mellifera (L). The consequences of reproduction for individual life expectancy can be studied directly by comparing reproductive and non-reproductive workers. We quantified the life span consequences of reproduction in honeybee workers by removal of the queen to trigger worker reproduction. Furthermore, we observed the social behavior of large cohorts of workers under experimental and control conditions to test for associations with individual life expectancy. Worker life expectancy was moderately increased by queen removal. Queenless colonies contained a few long-lived workers, and oviposition behavior was associated with a strong reduction in mortality risk, indicating that a reproductive role confers a significant survival advantage. This finding is further substantiated by an association between brood care behavior and worker longevity that depends on the social environment. In contrast, other in-hive activities, such as fanning, trophallaxis, and allogrooming did not consistently affect worker life expectancy. The influence of foraging varied among replicates. An earlier age of transitioning from in-hive tasks to outside foraging was always associated with shorter life spans, in accordance with previous studies. In sum, our studies quantify how individual mortality is affected by particular social roles and colony environments and demonstrate interactions between the two. The exceptional, positive association between reproduction and longevity in honeybees extends to within-caste plasticity, which may be exploited for mechanistic studies.

  2. Computed tomographic beam-hardening artefacts: mathematical characterization and analysis.

    PubMed

    Park, Hyoung Suk; Chung, Yong Eun; Seo, Jin Keun

    2015-06-13

    This paper presents a mathematical characterization and analysis of beam-hardening artefacts in X-ray computed tomography (CT). In the field of dental and medical radiography, metal artefact reduction in CT is becoming increasingly important as artificial prostheses and metallic implants become more widespread in ageing populations. Metal artefacts are mainly caused by the beam-hardening of polychromatic X-ray photon beams, which causes mismatch between the actual sinogram data and the data model being the Radon transform of the unknown attenuation distribution in the CT reconstruction algorithm. We investigate the beam-hardening factor through a mathematical analysis of the discrepancy between the data and the Radon transform of the attenuation distribution at a fixed energy level. Separation of cupping artefacts from beam-hardening artefacts allows causes and effects of streaking artefacts to be analysed. Various computer simulations and experiments are performed to support our mathematical analysis.

  3. A theoretical investigation of mixing thermodynamics, age-hardening potential, and electronic structure of ternary M11-xM2xB2 alloys with AlB2 type structure

    NASA Astrophysics Data System (ADS)

    Alling, B.; Högberg, H.; Armiento, R.; Rosen, J.; Hultman, L.

    2015-05-01

    Transition metal diborides are ceramic materials with potential applications as hard protective thin films and electrical contact materials. We investigate the possibility to obtain age hardening through isostructural clustering, including spinodal decomposition, or ordering-induced precipitation in ternary diboride alloys. By means of first-principles mixing thermodynamics calculations, 45 ternary M11-xM2xB2 alloys comprising MiB2 (Mi = Mg, Al, Sc, Y, Ti, Zr, Hf, V, Nb, Ta) with AlB2 type structure are studied. In particular Al1-xTixB2 is found to be of interest for coherent isostructural decomposition with a strong driving force for phase separation, while having almost concentration independent a and c lattice parameters. The results are explained by revealing the nature of the electronic structure in these alloys, and in particular, the origin of the pseudogap at EF in TiB2, ZrB2, and HfB2.

  4. A theoretical investigation of mixing thermodynamics, age-hardening potential, and electronic structure of ternary M11–xM2xB2 alloys with AlB2 type structure

    PubMed Central

    Alling, B.; Högberg, H.; Armiento, R.; Rosen, J.; Hultman, L.

    2015-01-01

    Transition metal diborides are ceramic materials with potential applications as hard protective thin films and electrical contact materials. We investigate the possibility to obtain age hardening through isostructural clustering, including spinodal decomposition, or ordering-induced precipitation in ternary diboride alloys. By means of first-principles mixing thermodynamics calculations, 45 ternary M11–xM2xB2 alloys comprising MiB2 (Mi = Mg, Al, Sc, Y, Ti, Zr, Hf, V, Nb, Ta) with AlB2 type structure are studied. In particular Al1–xTixB2 is found to be of interest for coherent isostructural decomposition with a strong driving force for phase separation, while having almost concentration independent a and c lattice parameters. The results are explained by revealing the nature of the electronic structure in these alloys, and in particular, the origin of the pseudogap at EF in TiB2, ZrB2, and HfB2. PMID:25970763

  5. A theoretical investigation of mixing thermodynamics, age-hardening potential, and electronic structure of ternary M(1)1-x M(2)xB2 alloys with AlB2 type structure.

    PubMed

    Alling, B; Högberg, H; Armiento, R; Rosen, J; Hultman, L

    2015-05-13

    Transition metal diborides are ceramic materials with potential applications as hard protective thin films and electrical contact materials. We investigate the possibility to obtain age hardening through isostructural clustering, including spinodal decomposition, or ordering-induced precipitation in ternary diboride alloys. By means of first-principles mixing thermodynamics calculations, 45 ternary M(1)1-x M(2)xB2 alloys comprising M(i)B2 (M(i) = Mg, Al, Sc, Y, Ti, Zr, Hf, V, Nb, Ta) with AlB2 type structure are studied. In particular Al1-xTixB2 is found to be of interest for coherent isostructural decomposition with a strong driving force for phase separation, while having almost concentration independent a and c lattice parameters. The results are explained by revealing the nature of the electronic structure in these alloys, and in particular, the origin of the pseudogap at EF in TiB2, ZrB2, and HfB2.

  6. Nutritional interventions protect against age-related deficits in behavior: from animals to humans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aged rats show impaired performance on motor and cognitive tasks. Similar changes in behavior occur in humans with age, and the development of methods to retard or reverse these age-related neuronal and behavioral deficits could increase healthy aging and decrease health care costs. In the present s...

  7. Single event upset hardening techniques

    SciTech Connect

    Weaver, H.T.; Corbett, W.T.

    1990-01-01

    Integrated circuit logic states are maintained by virtue of specific transistor combinations being either on'' (conducting) or off'' (nonconducting). High energy ion strikes on the microcircuit generate photocurrents whose primary detrimental effect is to make off'' transistors appear on,'' confusing the logic state and leading to single event upset (SEU). Protection against these soft errors is accomplished using either technology or circuit techniques, actions that generally impact yield and performance relative to unhardened circuits. We describe, and using circuit simulations analyze, a technique for hardening latches which requires combinations of technology and circuit modifications, but which provides SEU immunity without loss of speed. Specifically, a single logic state is hardened against SEU using technology methods and the information concerning valid states is then used to simplify hardened circuit design. The technique emphasizes some basic hardening concepts, ideas for which will be reviewed. 3 refs., 2 figs.

  8. System-Level Radiation Hardening

    NASA Technical Reports Server (NTRS)

    Ladbury, Ray

    2014-01-01

    Although system-level radiation hardening can enable the use of high-performance components and enhance the capabilities of a spacecraft, hardening techniques can be costly and can compromise the very performance designers sought from the high-performance components. Moreover, such techniques often result in a complicated design, especially if several complex commercial microcircuits are used, each posing its own hardening challenges. The latter risk is particularly acute for Commercial-Off-The-Shelf components since high-performance parts (e.g. double-data-rate synchronous dynamic random access memories - DDR SDRAMs) may require other high-performance commercial parts (e.g. processors) to support their operation. For these reasons, it is essential that system-level radiation hardening be a coordinated effort, from setting requirements through testing up to and including validation.

  9. Analyses and models of the autogenous shrinkage of hardening cement paste. 1: Modeling at macroscopic scale

    SciTech Connect

    Hua, C.; Ehrlacher, A.; Acker, P.

    1995-10-01

    After having studied phenomena linked to hydration and self-desiccation, one notes that capillary depression is the main origin of the autogenous shrinkage of hardening cement paste. Based on this mechanism, modeling at macroscopic scale is undertaken for a commonly used cement paste (CPA 55) with a W/C ratio = 0.42. It consists in introducing a macroscopic stress due to the capillary depression and characterizing the viscoelastic aging behavior of the material. The result is in satisfactory agreement with measurements.

  10. Behavioral activating effects of adrafinil in aged canines.

    PubMed

    Siwak, C T; Gruet, P; Woehrlé, F; Schneider, M; Muggenburg, B A; Murphey, H L; Callahan, H; Milgram, N W

    2000-06-01

    Adrafinil, a vigilance enhancing pharmaceutical, was administered to aged dogs for 14 consecutive days at doses of 10, 20, 30, or 40 mg/kg using a crossover design. The effects on spontaneous behavior in a 10-min canine open-field test were systematically recorded every fourth day, starting with day 1 of treatment. The open field tests were given 2 or 10 h following oral administration of capsules containing either adrafinil or lactose, the placebo control. Adrafinil caused an increase in locomotor activity at the three highest doses at both the 2- and 10-h intervals and during both the first (days 1 and 5) and second treatment week (days 9 and 13). Adrafinil also caused a transient increase in directed sniffing. At the highest dose level, adrafinil caused a decrease in urination frequency. The increased locomotion was generally unaccompanied by stereotypical behavior in the test session. There was some variability; a subpopulation of animals showed either no effect, or decreased locomotion. The individual differences were correlated with changes in serum levels of adrafinil 10 h following treatment. PMID:10880681

  11. The importance of genotype-by-age interactions for the development of repeatable behavior and correlated behaviors over lifetime

    PubMed Central

    2015-01-01

    Behaviors are highly plastic and one aspect of this plasticity is behavioral changes over age. The presence of age-related plasticity in behavior opens up the possibility of between-individual variation in age-related plasticity (Individual-Age interaction, IxA) and genotype-age interaction (GxA). We outline the available approaches for quantifying GxA. We underline that knowledge of GxA for behaviors is an important step in reaching and understanding of the evolution of plasticity in behavior over lifetime. In particular, the heritability (repeatability) and/or the rank order of behavior across individuals are predicted to change across ages in presence of GxA. We draw on the theory of reaction norms to illustrate that GxA, when present, is likely to lead to developmental changes in the magnitude and possibly sign of the genetic correlation between behaviors (behavioral syndrome). We present an overview of the literature on changes in the ranking of individuals’ behavior across ages, and in the correlation between behaviors. Although all studies were carried out on the phenotypic level, they overall suggest clear scope for increased study of GxA as a process explaining age-related plasticity in behaviors. Lastly, we throughout emphasize that many of the approaches and underlying theory of GxA is applicable to the study of IxA, which is informative as it presents the upper limit of GxA, but is also a more attainable target of study in many systems. Empirical work aimed at understanding IxA and GxA in behavior is needed in order to understand whether patterns predicted by theory on plasticity indeed occur for age-related plasticity of behavior. PMID:26816518

  12. Precipitation hardening of a beta-titanium alloy by the alpha-two phase. Technical report

    SciTech Connect

    Quattrocchi, L.S.; Koss, D.A.; Scarr, G.

    1991-09-25

    The age hardening of beta titanium alloys by the formation of ordered alpha two precipitates based on Ti3Al has been investigated by transmission electron microscopy and hardness observations. Results of tests based on the alloy Ti 23Nb 11 Al (at. %) show a large precipitation hardening response at temperatures considerably higher than is possible in current beta titanium alloys. TEM identifies the hardening to be caused by the formation of ordered, alpha two precipitates.

  13. Solute hardening and softening effects in B2 nickel aluminides

    SciTech Connect

    Pike, L.M.; Liu, C.T.; Anderson, I.M.; Chang, Y.A.

    1998-11-01

    The effect of substitutional solute additions including Fe, Mn, and Pd on the hardness of B2-ordered NiAl alloys was investigated. The solid solution hardening behavior of intermetallics is more complex than that of typical metallic solid solutions because of complications arising from the site preference of the solute as well as the effects of the solute on the concentrations of other point defects, e.g., vacancies and anti-site defects. For this reason, care was taken to experimentally establish solute site preferences and point defect concentrations in the NiAl alloys before analyzing the hardness data. By taking these factors into account it was possible to rationalize the observed unusual hardening effects. Three distinct categories of solid solution hardening behavior were encountered. The first was hardening by the solute addition itself. This was observed in the case of Pd additions to Al-poor NiAl. However, when fe or Mn is added to Al-poor NiAl a second category is observed; these elements are seen to soften the material. The third category of behavior is observed when Fe is added to NiAl with a constant Al concentration of 50 at. %. In this case it is vacancies, rather than solute atoms, which harden the material.

  14. Age Differences and Changes of Coping Behavior in Three Age Groups: Findings from the Georgia Centenarian Study

    ERIC Educational Resources Information Center

    Martin, Peter; Kliegel, Matthias; Rott, Christoph; Poon, Leonard W.; Johnson, Mary Ann

    2008-01-01

    With increasing age, older adults are more likely to be challenged by an increasing number of physical, functional and social losses. As a result, coping with losses becomes a central theme in very late life. This study investigated age differences and age changes in active behavioral, active cognitive and avoidance coping and related coping to…

  15. Anisotropic hardening model based on non-associated flow rule and combined nonlinear kinematic hardening for sheet materials

    NASA Astrophysics Data System (ADS)

    Taherizadeh, Aboozar; Green, Daniel E.; Yoon, Jeong W.

    2013-12-01

    A material model for more effective analysis of plastic deformation of sheet materials is presented in this paper. The model is capable of considering the following aspects of plastic deformation behavior of sheet materials: the anisotropy in yielding stresses in different directions by using a quadratic yield function (based on Hill's 1948 model and stress ratios), the anisotropy in work hardening by introducing non-constant flow stress hardening in different directions, the anisotropy in plastic strains in different directions by using a quadratic plastic potential function and non-associated flow rule (based on Hill's 1948 model and plastic strain ratios, r-values), and finally some of the cyclic hardening phenomena such as Bauschinger's effect and transient behavior for reverse loading by using a coupled nonlinear kinematic hardening (so-called Armstrong-Frederick-Chaboche model). Basic fundamentals of the plasticity of the model are presented in a general framework. Then, the model adjustment procedure is derived for the plasticity formulations. Also, a generic numerical stress integration procedure is developed based on backward-Euler method (so-called multi-stage return mapping algorithm). Different aspects of the model are verified for DP600 steel sheet. Results show that the new model is able to predict the sheet material behavior in both anisotropic hardening and cyclic hardening regimes more accurately. By featuring the above-mentioned facts in the presented constitutive model, it is expected that more accurate results can be obtained by implementing this model in computational simulations of sheet material forming processes. For instance, more precise results of springback prediction of the parts formed from highly anisotropic hardened materials or that of determining the forming limit diagrams is highly expected by using the developed material model.

  16. Ageing characteristics of aluminium alloy aluminosilicate discontinuous fiber reinforced composites

    SciTech Connect

    Nath, D.; Singh, V.

    1999-03-05

    Development of continuous fiber reinforced metal matrix composites is aimed at providing high specific strength and stiffness needed for aerospace and some critical high temperature structural applications. Considerable efforts have been made, during the last decade, to improve the strength of age-hardening aluminium alloy matrix composites by suitable heat treatment. It has also been well established that age-hardenable aluminium alloy composites show accelerated ageing behavior because of enhanced dislocation density at the fiber/matrix interface resulting from thermal expansion mismatch between ceramic fiber and the metal matrix. The accelerated ageing of aluminium alloy composites either from dislocation density or the residual stress, as a result of thermal expansion mismatch is dependent on the size of whisker and particulate. Investigations have also been made on the effect of volume fraction of particulate on the ageing behavior of aluminium alloys. The present investigation is concerned with characterization of age-hardening behavior of an Al-Si-Cu-Mg(AA 336) alloy alumino-silicate discontinuous fiber-reinforced composites (referred to as aluminium MMCs in the present text) being developed for automotive pistons. An effort is made to study the effect of volume fraction of the reinforcement on age-hardening behavior of this composite.

  17. Influence of Aging Treatments on Alterations of Microstructural Features and Stress Corrosion Cracking Behavior of an Al-Zn-Mg Alloy

    NASA Astrophysics Data System (ADS)

    Rout, Prasanta Kumar; Ghosh, M. M.; Ghosh, K. S.

    2015-07-01

    7xxx series Al-Zn-Mg-(Cu) alloys have higher strength in their peak-aged (T6) states compared with other age-hardenable aluminum alloys; however, the maximum strength peak-aged state is more susceptible to stress corrosion cracking (SCC) which leads to catastrophic failure. The over-aged (T7) temper with 10-15% lower strength has higher resistance to SCC requiring oversized structural aerospace component applications. The medium-strength AA7017 Al-Zn-Mg weldable alloy without Cu is also prone to SCC under certain environmental conditions. In the present investigation, the SCC behaviors of an AA7017 Al-Zn-Mg alloys of different tempers have been assessed. Specific aging schedules have been adapted to an AA7017 alloy to produce various tempers, e.g., under-, peak-(T6), over-(T7), and highly over-aged tempers. Artificial aging behavior of the AA7017 alloy has been characterized by hardness, electrical conductivity measurements, x-ray diffraction, differential scanning calorimetry, and electrochemical studies. Slow strain rate test technique was used to assess the SCC behaviors of the AA7017 alloys of under-, T6, T7, and highly over-aged tempers in 3.5 wt.% NaCl solution at free corrosion potential (FCP) and at applied anodic potential, as well. Results revealed that the AA7017 alloy tempers are not susceptible to SCC in 3.5 wt.% NaCl solution at FCP, but severely damaging to SCC at applied anodic potentials. Microstructural features, showing a non-recrystallized grain structure and the presence of discrete, widely spaced, not-interconnected η precipitates at the grain boundaries, are the contributive factors by virtue of which the alloy tempers at FCP did not exhibit SCC. However, the applied anodic potential resulted in rapid metal dissolution from the grain boundary region and led to SCC. The local anodic dissolution (LAD) is believed to be the associated SCC mechanism.

  18. Enabling Strain Hardening Simulations with Dislocation Dynamics

    SciTech Connect

    Arsenlis, A; Cai, W

    2006-12-20

    Numerical algorithms for discrete dislocation dynamics simulations are investigated for the purpose of enabling strain hardening simulations of single crystals on massively parallel computers. The algorithms investigated include the /(N) calculation of forces, the equations of motion, time integration, adaptive mesh refinement, the treatment of dislocation core reactions, and the dynamic distribution of work on parallel computers. A simulation integrating all of these algorithmic elements using the Parallel Dislocation Simulator (ParaDiS) code is performed to understand their behavior in concert, and evaluate the overall numerical performance of dislocation dynamics simulations and their ability to accumulate percents of plastic strain.

  19. Age and HIV Risk and Protective Behaviors among African American Women

    ERIC Educational Resources Information Center

    Corneille, Maya A.; Zyzniewski, Linda E.; Belgrave, Faye Z.

    2008-01-01

    Though HIV prevention efforts have focused on young adult women, women of all ages may engage in HIV risk behaviors and experience barriers to condom use. This article examines the effect of age on sexual risk and protective attitudes and behaviors among African American women. Unmarried heterosexual African American women between the ages of 18…

  20. Dynamic bake hardening of interstitial-free steels

    SciTech Connect

    Dehghani, K.; Jonas, J.J.

    2000-05-01

    Two types of dynamic strain aging (DSA) strengthening methods were investigated to determine their potentials for industrial use. They are referred to here as dynamic-static bake hardening (DSBH) and dynamic bake hardening (DBH). For this purpose, a 0.06 pct Ti interstitial-free (IF) steel was reheated to 900 C and cooled at 12 C/s to room temperature. It was then dynamically bake hardened in the temperature range 100 C to 250 C to strains of 2 to 8 pct at a strain rate of 10{sup {minus}3} s{sup {minus}1}. The tensile properties were determined before and after these treatments. It was found that the occurrence of DSA during dynamic baking led to significant increases in work-hardening rate as well as in the final strength. The results indicate that, for a given solute carbon level, the dynamically and then statically aged samples have higher strengths than those that are bake hardened in the conventional way.

  1. Mechanism of work hardening in Hadfield manganese steel

    NASA Astrophysics Data System (ADS)

    Dastur, Y. N.; Leslie, W. C.

    1981-05-01

    When Hadfield manganese steel in the single-phase austenitic condition was strained in tension, in the temperature range - 25 to 300 °C, it exhibited jerky (serrated) flow, a negative (inverse) strain-rate dependence of flow stress and high work hardening, characteristic of dynamic strain aging. The strain rate-temperature regime of jerky flow was determined and the apparent activation energies for the appearance and disappearance of serrations were found to be 104 kJ/mol and 146 kJ/mol, respectively. The high work hardening cannot be a result of mechanical twinning because at -50 °C numerous twins were produced, but the work hardening was low and no twins were formed above 225 °C even though work hardening was high. The work hardening decreased above 300 °C because of the cessation of dynamic strain aging and increased again above 400 °C because of precipitation of carbides. An apparent activation energy of 138 kJ/mol was measured for static strain aging between 300 and 400 °C, corresponding closely to the activation energies for the disapperance of serrations and for the volume diffusion of carbon in Hadfield steel. Evidence from the present study, together with the known effect of manganese on the activity of carbon in austenite and previous internal friction studies of high-manganese steels, lead to the conclusion that dynamic strain aging, brought about by the reorientation of carbon members of C-Mn couples in the cores of dislocations, is the principal cause of rapid work hardening in Hadfield steel.

  2. Relating Age Change and Behavior to Job Requirements.

    ERIC Educational Resources Information Center

    Schaie, K. Warner

    The Age Discrimination in Employment Act has been amended to outlaw mandatory retirement at any age. However, the act permits employers to impose a specific retirement age if there is a bona fide occupational qualification (BFOQ) which cannot be met by all or most individuals. Imposition of BFOQ mandatory retirement ages by employers has led to…

  3. Reduced Electrodermal Fear Conditioning from Ages 3 to 8 Years Is Associated with Aggressive Behavior at Age 8 Years

    PubMed Central

    Gao, Yu; Raine, Adrian; Venables, Peter H.; Dawson, Michael E.; Mednick, Sarnoff A.

    2010-01-01

    Background Poor fear conditioning characterizes adult psychopathy and criminality, but it is not known whether it is related to aggressive/antisocial behavior in early childhood. Methods Using a differential, partial reinforcement conditioning paradigm, electrodermal activity was recorded from 200 male and female children at ages 3, 4, 5, 6, and 8 years. Antisocial/aggressive and hyperactive-inattentive measures were collected at age 8, while social adversity was assessed at age 3. Results Poor electrodermal fear conditioning from ages 3 to 8 years was associated with aggressive behavior at age 8 in both males and females. Conclusions Results indicate that the relationship between poor fear conditioning and aggression occurs early in childhood. Enhanced electrodermal fear conditioning may protect children against future aggressive/violent behavior. Abnormal amygdala functioning, as indirectly assessed by fear conditioning, may be one of the factors influencing the development of childhood aggression. PMID:19788551

  4. Relationship between impulsiveness and deviant behavior among adolescents in the classroom: age and sex differences.

    PubMed

    Esteban, Angeles; Tabernero, Carmen

    2011-12-01

    To assess the relationship between impulsiveness and deviant behavior among 103 adolescents, taking into account their sociodemographic characteristics, the Barratt Impulsiveness Scale and a self-assessment measure with regard to disruptive and deviant behaviors which had occurred in the last 90 days were used. The results show that impulsiveness and disruptive behavior in the classroom were related to deviant behavior outside of the classroom. Therefore, age and sex explained the relationship between impulsiveness and behavior. The older adolescents and the girls showed less disruptive behaviors than the younger participants and the boys; both variables showed an interactive effect on disruptive behavior. The age at which sexual activity commenced and the number of sexual partners were also significantly related to impulsiveness and disruptive and deviant behavior. Similarly, impulsiveness was shown to have a significant relationship with disruptive and deviant behavior, and disruptive behavior was shown to have a significant relationship with deviant behavior.

  5. Trajectories of Externalizing Behavior from Age 2 to Age 9: Relations with Gender, Temperament, Ethnicity, Parenting, and Rater

    ERIC Educational Resources Information Center

    Miner, Jennifer L.; Clarke-Stewart, K. Alison

    2008-01-01

    Trajectories of children's externalizing behavior were examined using multilevel growth curve modeling of data from the NICHD Study of Early Child Care and Youth Development. According to ratings by both mothers and caregivers/teachers when children were 2, 3, 4, 7, and 9 years old, externalizing behavior declined with age. However, mothers rated…

  6. Total dose performance of radiation hardened voltage regulators and references

    NASA Technical Reports Server (NTRS)

    McClure, S.; Gorelick, J.; Pease, R.; Rax, B.; Ladbury, R.

    2001-01-01

    Total dose test of commercially available radiation hardened bipolar voltage regulators and references show reduced sensitivity to dose rate and varying sensitivity to bias under pressure. Behavior of critical parameters in different dose rate and bias conditions is compared and the impact to hardness assurance methodology is discussed.

  7. Aggressive versus Nonaggressive Antisocial Behavior: Distinctive Etiological Moderation by Age

    ERIC Educational Resources Information Center

    Burt, S. Alexandra; Neiderhiser, Jenae M.

    2009-01-01

    Research has supported the existence of distinct behavioral patterns, demographic correlates, and etiologic mechanisms for aggressive (AGG) versus nonaggressive but delinquent (DEL) antisocial behavior. Though behavioral genetic studies have the potential to further crystallize these dimensions, inconsistent results have limited their…

  8. Strain hardening during mechanical twining and dislocation channeling in irradiated 316 stainless steels

    SciTech Connect

    Byun, Thak Sang; Hashimoto, Naoyuki

    2007-01-01

    Localized deformation mechanisms and strain-hardening behaviors in irradiated 316 and 316LN stainless steels were investigated, and a theoretical model was proposed to explain the linear strain-hardening behavior during the localized deformation. After low temperature irradiation to significant doses the deformation microstructure changed from dislocation tangles to channels or to mechanical twins. It was also observed that irradiation hardening straightened gliding dislocations and increased the tendency for forming pileups. Regardless of these microstructural changes, the strain-hardening behavior was relatively insensitive to the irradiation. This dose-independent strain-hardening rate resulted in dose independence of the true stress parameters such as the plastic instability stress and true fracture stress. In the proposed model, the long-range back stress was formulated as a function of the number of pileup dislocations per slip band and the number of slip bands in a grain. The calculation results confirmed the experimental observation that strain-hardening rate was insensitive to the change in deformation mechanism because the long-range back stress hardening became as high as the hardening by tangled dislocations.

  9. Production and Precipitation Hardening of Beta-Type Ti-35Nb-10Cu Alloy Foam for Implant Applications

    NASA Astrophysics Data System (ADS)

    Mutlu, Ilven; Yeniyol, Sinem; Oktay, Enver

    2016-04-01

    In this study, beta-type Ti-35Nb-10Cu alloy foams were produced by powder metallurgy method for dental implant applications. 35% Nb was added to stabilize the beta-Ti phase with low Young's modulus. Cu addition enhanced sinterability and gave precipitation hardening capacity to the alloy. Sintered specimens were precipitation hardened in order to enhance the mechanical properties. Electrochemical corrosion behavior of the specimens was examined by electrochemical impedance spectroscopy in artificial saliva. Electrochemical impedance spectroscopy results indicated that the oxide film on the surface of foam is a bi-layer structure consisting of outer porous layer and inner barrier layer. Impedance values of barrier layer were higher than porous layer. Corrosion resistance of specimens decreased at high fluoride concentrations and at low pH of artificial saliva. Corrosion resistance of alloys was slightly decreased with aging. Mechanical properties, microstructure, and surface roughness of the specimens were also examined.

  10. Statistical thermodynamics of strain hardening in polycrystalline solids

    DOE PAGES

    Langer, James S.

    2015-09-18

    This paper starts with a systematic rederivation of the statistical thermodynamic equations of motion for dislocation-mediated plasticity proposed in 2010 by Langer, Bouchbinder, and Lookman. The paper then uses that theory to explain the anomalous rate-hardening behavior reported in 1988 by Follansbee and Kocks and to explore the relation between hardening rate and grain size reported in 1995 by Meyers et al. A central theme is the need for physics-based, nonequilibrium analyses in developing predictive theories of the strength of polycrystalline materials.

  11. Statistical thermodynamics of strain hardening in polycrystalline solids.

    PubMed

    Langer, J S

    2015-09-01

    This paper starts with a systematic rederivation of the statistical thermodynamic equations of motion for dislocation-mediated plasticity proposed in 2010 by Langer, Bouchbinder, and Lookman [Acta Mat. 58, 3718 (2010)ACMAFD1359-645410.1016/j.actamat.2010.03.009]. It then uses that theory to explain the anomalous rate-hardening behavior reported in 1988 by Follansbee and Kocks and to explore the relation between hardening rate and grain size reported in 1995 by Meyers et al. A central theme is the need for physics-based, nonequilibrium analyses in developing predictive theories of the strength of polycrystalline materials.

  12. Statistical thermodynamics of strain hardening in polycrystalline solids

    SciTech Connect

    Langer, James S.

    2015-01-01

    This paper starts with a systematic rederivation of the statistical thermodynamic equations of motion for dislocation-mediated plasticity proposed in 2010 by Langer, Bouchbinder, and Lookman. The paper then uses that theory to explain the anomalous rate-hardening behavior reported in 1988 by Follansbee and Kocks and to explore the relation between hardening rate and grain size reported in 1995 by Meyers et al. A central theme is the need for physics-based, nonequilibrium analyses in developing predictive theories of the strength of polycrystalline materials.

  13. Effect of moisture on the aging behavior of asphalt binder

    NASA Astrophysics Data System (ADS)

    Ma, Tao; Huang, Xiao-Ming; Mahmoud, Enad; Garibaldy, Emil

    2011-08-01

    The moisture aging effect and mechanism of asphalt binder during the in-service life of pavement were investigated by laboratory simulating tests. Pressure aging vessel (PAV) test simulating the long-term aging of binder during the in-service life of pavement was modified to capture the long-term moisture aging effect of binder. Penetration grade tests including penetration test, soften point test, and ductility test as well as Superpave™ performance grade tests including viscosity test, dynamic shear rheometer test, and bending beam rheometer test were conducted to fully evaluate the moisture aging effect of binder. Fourier transform infrared spectroscopy test and Gel-permeation chromatography test were applied to provide a fundamental understanding of the moisture aging mechanism of binder. The results indicate that moisture condition can accelerate the aging of asphalt binder and shorten the service life of asphalt binder. The modified PAV test with moisture condition can well characterize the moisture aging properties of asphalt binder.

  14. Life on the Hardened Border

    ERIC Educational Resources Information Center

    Miller, Bruce Granville

    2012-01-01

    The many Coast Salish groups distributed on both sides of the United States-Canada border on the Pacific coast today face significant obstacles to cross the international border, and in some cases are denied passage or intimidated into not attempting to cross. The current situation regarding travel by Aboriginal people reflects the "hardening" of…

  15. Rural Adolescent Health Risk Behaviors: Age, Gender, and Ethnic Differences.

    ERIC Educational Resources Information Center

    Salzman, Stephanie A.; Girvan, James T.

    A survey of health risk behaviors was administered to a representative sample of 7,776 Idaho students in grades 8-12. Respondents were 86% White, 6% Hispanic, 4% American Indian, 3% Asian, and 2% Black. These rural adolescents reported that they had engaged in some health risk behaviors at rates comparable to those of other U.S. adolescents: 57%…

  16. An Evaluation of the Aberrant Behavior Checklist for Children under Age 5

    ERIC Educational Resources Information Center

    Schmidt, Jonathan D.; Huete, John M.; Fodstad, Jill C.; Chin, Michelle D.; Kurtz, Patricia F.

    2013-01-01

    Severe problem behaviors such as self-injury and aggression are frequently observed in young children under age 5 with intellectual and developmental disabilities (IDD). Although early identification of problem behavior is critical to effective intervention, there are few standardized measures available that identify severe problem behavior in…

  17. Beneficial effects of berryfruit polyphenols on neuronal behavioral aging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is becoming increasingly clear that although there is a great deal of research being devoted to elucidating the molecular mechanisms involved in aging, practical information on how to forestall or reverse the deleterious effects of aging may be years away. Therefore, it may be beneficial to dete...

  18. Sexual interest, attitudes, knowledge, and sexual history in relation to sexual behavior in the institutionalized aged.

    PubMed

    White, C B

    1982-02-01

    Although the idea that sexuality is a lifelong need is gaining greater research support and greater acceptability to the general public, few consider the institutionalized aged as having sexual needs or being able to benefit from sexual intimacy. The research presented here indicates that sexual activity in the institutionalized aged is related to their attitudes and behavior toward sexuality and to their sexual interest level and prior frequency of sexual activity. Institutionalized aged persons evidence sexual needs and do engage in sexual behavior.

  19. Precipitation Behavior During Aging in α Phase Titanium Supersaturated with Cu

    NASA Astrophysics Data System (ADS)

    Mitsuhara, Masatoshi; Masuda, Tomoya; Nishida, Minoru; Kunieda, Tomonori; Fujii, Hideki

    2016-04-01

    Age hardening of Ti-2.3 mass pct Cu (Ti-2.3Cu) at 673 K to 873 K (400 °C to 600 °C) after solution treatment at 1063 K (790 °C) was observed. The relationship between precipitates formed during aging and changes in hardness was investigated. During aging at 673 K (400 °C), the hardness increased rapidly up to 200 hours, and subsequently increased more slowly up to 1000 hours. At 873 K (600 °C), the hardness began to decrease immediately. Transmission electron microscopy showed that fine disk-shaped precipitates of 20 to 40 nm in diameter grew in the α phase. It is concluded that these precipitates interacted with dislocations and increased the hardness. At 873 K (600 °C), precipitates of 1 µm in length and Ti2Cu particles of 200 nm in length were observed. The decrease in hardness may have resulted from the precipitate formation decreasing the concentration of Cu in the α phase. Bright/dark contrast of the three atomic layers and small atomic shift of the hcp structure were observed in the atomic resolution imaging of the precipitates. This suggests that the precipitates are not just Cu-enriched zones and have structures with similar periodicity to the Ti2Cu phase, which is thermally stable at those aging temperatures.

  20. Behavioral Group Work in a Home for the Aged

    ERIC Educational Resources Information Center

    Linsk, N.; And Others

    1975-01-01

    Elderly people in institutions frequently become isolated and noncommunicative. By using behavioral measurements of group workers and group members, the authors have formulated ways of treatment that encourage members to participate more actively. (Author)

  1. Kinematic hardening in creep of Zircaloy

    NASA Astrophysics Data System (ADS)

    Sedláček, Radan; Deuble, Dietmar

    2016-10-01

    Results of biaxial creep tests with stress changes on Zircaloy-2 tube samples are presented. A Hollomon-type viscoplastic strain hardening model is extended by the Armstrong-Frederic nonlinear kinematic hardening law, resulting in a mixed (i.e. isotropic and kinematic) strain hardening model. The creep tests with stress changes and similar tests published in the literature are simulated by the models. It is shown that introduction of the kinematic strain hardening in the viscoplastic strain hardening model is sufficient to describe the creep transients following stress drops, stress reversals and stress removals.

  2. Grape powder treatment prevents anxiety-like behavior in a rat model of aging.

    PubMed

    Patki, Gaurav; Ali, Quaisar; Pokkunuri, Indira; Asghar, Mohammad; Salim, Samina

    2015-06-01

    Earlier, we have reported that grape powder (GP) treatment prevented pharmacologic and psychological stress-induced anxiety-like behavior and memory impairment in rats. Protective effects of GP were attributed to its antioxidant effects. In this study, we tested the hypothesis that age-associated behavioral and cognitive deficits such as anxiety and memory impairment will be ameliorated with GP treatment. Using a National Institute of Aging recommended rodent model of aging, we examined a potentially protective role of antioxidant-rich GP in age-associated anxiety-like behavior and memory impairment. Male Fischer 344 rats were randomly assigned into 4 groups: young rats (3 months old) provided with tap water or with 15 g/L GP dissolved in tap water for 3 weeks, aged rats (21 months old) provided with tap water or with GP-treated tap water for 3 weeks (AG-GP). Anxiety-like behavior was significantly greater in aged rats compared with young rats, GP-treated young rats, or aged control rats (P < .05). Also, GP treatment prevented age-induced anxiety-like behavior in AG-GP rats (P < .05). Neither short-term nor long-term age-associated memory deficits improved with GP treatment in AG-GP rats. Furthermore, aged rats showed increased level of physiological stress (corticosterone) and increased oxidative stress in the plasma (8-isoprostane) as well as in selected brain areas (protein carbonylation). Grape powder treatment prevented age-induced increase in corticosterone levels and plasma 8-isoprostane levels in aged rats (P < .05), whereas protein carbonylation was recovered in the amygdala region only (P < .05). Grape powder by regulating oxidative stress ameliorates age-induced anxiety-like behavior in rats, whereas age-associated memory deficits seem unaffected with GP treatment.

  3. Surface Fatigue Resistance with Induction Hardening

    NASA Technical Reports Server (NTRS)

    Townsend, Dennis; Turza, Alan; Chapman, Mike

    1996-01-01

    Induction hardening has been used for some years to harden the surface and improve the strength and service life of gears and other components. Many applications that employ induction hardening require a relatively long time to finish the hardening process and controlling the hardness of the surface layer and its depth often was a problem. Other surface hardening methods, ie., carbonizing, take a very long time and tend to cause deformations of the toothing, whose elimination requires supplementary finishing work. In double-frequency induction hardening, one uses a low frequency for the preheating of the toothed wheel and a much higher frequency for the purpose of rapidly heating the surface by way of surface hardening.

  4. Effects of age, dietary, and behavioral enrichment on brain mitochondria in a canine model of human aging.

    PubMed

    Head, E; Nukala, V N; Fenoglio, K A; Muggenburg, B A; Cotman, C W; Sullivan, P G

    2009-11-01

    Dogs develop cognitive decline and a progressive accumulation of oxidative damage. In a previous longitudinal study, we demonstrated that aged dogs treated with either an antioxidant diet or with behavioral enrichment show cognitive improvement. The antioxidant diet included cellular antioxidants (vitamins E and C, fruits and vegetables) and mitochondrial cofactors (lipoic acid and carnitine). Behavioral enrichment consisted of physical exercise, social enrichment, and cognitive training. We hypothesized that the antioxidant treatment improved neuronal function through increased mitochondrial function. Thus, we measured reactive oxygen species (ROS) production and bioenergetics in mitochondria isolated from young, aged, and treated aged animals. Aged canine brain mitochondria show significant increases in ROS production and a reduction in NADH-linked respiration. Mitochondrial function (ROS and NADH-linked respiration) was improved selectively in aged dogs treated with an antioxidant diet. In contrast, behavioral enrichment had no effect on any mitochondrial parameters. These results suggest that an antioxidant diet improves cognition by maintaining mitochondrial homeostasis, which may be an independent molecular pathway not engaged by behavioral enrichment.

  5. Effects of age, dietary, and behavioral enrichment on brain mitochondria in a canine model of human aging.

    PubMed

    Head, E; Nukala, V N; Fenoglio, K A; Muggenburg, B A; Cotman, C W; Sullivan, P G

    2009-11-01

    Dogs develop cognitive decline and a progressive accumulation of oxidative damage. In a previous longitudinal study, we demonstrated that aged dogs treated with either an antioxidant diet or with behavioral enrichment show cognitive improvement. The antioxidant diet included cellular antioxidants (vitamins E and C, fruits and vegetables) and mitochondrial cofactors (lipoic acid and carnitine). Behavioral enrichment consisted of physical exercise, social enrichment, and cognitive training. We hypothesized that the antioxidant treatment improved neuronal function through increased mitochondrial function. Thus, we measured reactive oxygen species (ROS) production and bioenergetics in mitochondria isolated from young, aged, and treated aged animals. Aged canine brain mitochondria show significant increases in ROS production and a reduction in NADH-linked respiration. Mitochondrial function (ROS and NADH-linked respiration) was improved selectively in aged dogs treated with an antioxidant diet. In contrast, behavioral enrichment had no effect on any mitochondrial parameters. These results suggest that an antioxidant diet improves cognition by maintaining mitochondrial homeostasis, which may be an independent molecular pathway not engaged by behavioral enrichment. PMID:19703441

  6. Scintillation-Hardened GPS Receiver

    NASA Technical Reports Server (NTRS)

    Stephens, Donald R.

    2015-01-01

    CommLargo, Inc., has developed a scintillation-hardened Global Positioning System (GPS) receiver that improves reliability for low-orbit missions and complies with NASA's Space Telecommunications Radio System (STRS) architecture standards. A software-defined radio (SDR) implementation allows a single hardware element to function as either a conventional radio or as a GPS receiver, providing backup and redundancy for platforms such as the International Space Station (ISS) and high-value remote sensing platforms. The innovation's flexible SDR implementation reduces cost, weight, and power requirements. Scintillation hardening improves mission reliability and variability. In Phase I, CommLargo refactored an open-source GPS software package with Kalman filter-based tracking loops to improve performance during scintillation and also demonstrated improved navigation during a geomagnetic storm. In Phase II, the company generated a new field-programmable gate array (FPGA)-based GPS waveform to demonstrate on NASA's Space Communication and Navigation (SCaN) test bed.

  7. Undergraduate Students' Perceptions and Behaviors Related to the Aged and to Aging Processes

    ERIC Educational Resources Information Center

    Van Dussen, Daniel J.; Weaver, Robert R.

    2009-01-01

    Aging education is relatively new to the university, and our understanding of the perspectives students bring to aging populations is correspondingly limited. This investigation surveys 546 students at a midsized, Midwestern university to explore students' views toward elders, toward serving elders, and toward the relevance of aging education for…

  8. Sex differences in neurochemical markers that correlate with behavior in aging mice.

    PubMed

    Frick, K M; Burlingame, L A; Delaney, S S; Berger-Sweeney, J

    2002-01-01

    Sex differences in neurochemical markers that correlate with behavior in aging mice NEUROBIOL AGING. We examined whether the enzymatic activities of choline acetyltransferase (ChAT) and glutamic acid decarboxylase (GAD) were altered similarly with age in male and female mice, and whether these changes were correlated with age-related alterations in memory and anxiety. ChAT and GAD activities were measured in neocortex, hippocampus, and striatum of behaviorally characterized male and female C57BL/6 mice (5, 17, and 25 months). Generally, ChAT activity was increased, and GAD activity decreased, with age. However, disparate changes were revealed between the sexes; activities of both enzymes were decreased in 17-month males, whereas alterations in females were not observed until 25-months. Furthermore, enzyme-behavior correlations differed between the sexes; in males, ChAT activity was related to one behavioral task, whereas in females, activities of both enzymes were correlated with multiple tasks. Significant enzyme-behavior correlations were most evident at 17 months of age, likely the result of behavioral and enzymatic sex differences at this age. These data represent the first comprehensive report illustrating differential alterations of ChAT and GAD activities in aging male and female mice.

  9. Dilatant hardening of fluid-saturated sandstone

    NASA Astrophysics Data System (ADS)

    Makhnenko, Roman Y.; Labuz, Joseph F.

    2015-02-01

    The presence of pore fluid in rock affects both the elastic and inelastic deformation processes, yet laboratory testing is typically performed on dry material even though in situ the rock is often saturated. Techniques were developed for testing fluid-saturated porous rock under the limiting conditions of drained, undrained, and unjacketed response. Confined compression experiments, both conventional triaxial and plane strain, were performed on water-saturated Berea sandstone to investigate poroelastic and inelastic behavior. Measured drained response was used to calibrate an elasto-plastic constitutive model that predicts undrained inelastic deformation. The experimental data show good agreement with the model: dilatant hardening in undrained triaxial and plane strain compression tests under constant mean stress was predicted and observed.

  10. Hardening and yielding in colloidal gels

    NASA Astrophysics Data System (ADS)

    Del Gado, Emanuela; Colombo, Jader; Bouzid, Mehdi

    Attractive colloidal gel networks are disordered elastic solids that can form even in extremely dilute particle suspensions. With interaction strengths comparable to the thermal energy, their stress-bearing network can locally restructure via breaking and reforming inter-particle bonds. We use molecular dynamics simulations of a model system to investigate the strain hardening and the yielding process. During shear start up protocol, the system exhibits strong localization of tensile stresses that may be released through the breaking and formation of new bonds. In this regime, the small amplitude oscillatory shear analysis shows that the storage and the loss modulus follow a power law behavior that are closely reminiscent of experimental observations. At large accumulated strains, the strain-induced reorganization of the gel may trigger flow heterogeneities and eventually lead to the yielding of the gel via a quasi brittle damage of its structure.

  11. Self-assessed driving behaviors associated with age among middle-aged and older adults in Japan.

    PubMed

    Arai, Asuna; Arai, Yumiko

    2015-01-01

    With the increasing number of older drivers, road traffic safety is an urgent public health issue. It is not easy for older drivers or their relatives to detect early signs of dangerous driving behaviors. We examine the types of driving behavior that increase in frequency with age. We surveyed people aged 40 and over among the general public in Japan using a self-administered questionnaire on sociodemographic factors, driving status, frequency of driving, 12-items on physical symptoms possibly related to driving performance, and 28-items on driving behaviors. Multiple logistic regression models were used to estimate the odds ratios (OR) of occurrence of each of the 28 driving behaviors for a 5-year increase in age. Significant associations with a 5-year increase in age after adjusting for confounding factors were found for the following directly unsafe driving behaviors: (1) little or no sign of attempts to avoid dangerous situations (OR for a 5-year increase in age=1.38, 95% CI: 1.18-1.63); (2) lack of attention to other people and cars (1.33, 1.12-1.60); (3) improper maneuvering around curves (1.33, 1.09-1.65); and (4) improper or no turn signals (1.33, 1.06-1.69). Information about these driving behaviors should be given to drivers and their stakeholders and used to caution participants when implementing educational programs for older drivers. Self-assessment of driving ability in older drivers provides useful information to raise awareness of their driving performance.

  12. Age Differences in the Impact of Employment on Antisocial Behavior

    ERIC Educational Resources Information Center

    Monahan, Kathryn C.; Steinberg, Laurence; Cauffman, Elizabeth

    2013-01-01

    While research suggests that working more than 20 hr weekly is associated with greater antisocial behavior among middle- and upper-class youth, some have argued that employment benefits at-risk youth and leads to desistance from crime among youthful offenders. This study investigates the relation between hours worked, school attendance, and…

  13. Behavior Correlates of Rorschach Response in School Age Children.

    ERIC Educational Resources Information Center

    Martin, Frances G.

    Teachers in a private special education school for students with learning and/or adjustment difficulties completed Bristol Social Adjustment Guides (BSAGs), an observation scale for identifying maladaptive classroom behaviors, for 157 students (7-21 years old). Rorschachs were administered to the same group of students. Data from each test were…

  14. Reduced Electrodermal Fear Conditioning from Ages 3 to 8 Years Is Associated with Aggressive Behavior at Age 8 Years

    ERIC Educational Resources Information Center

    Gao, Yu; Raine, Adrian; Venables, Peter H.; Dawson, Michael E.; Mednick, Sarnoff A.

    2010-01-01

    Background: Poor fear conditioning characterizes adult psychopathy and criminality, but it is not known whether it is related to aggressive/antisocial behavior in early childhood. Methods: Using a differential, partial reinforcement conditioning paradigm, electrodermal activity was recorded from 200 male and female children at ages 3, 4, 5, 6, and…

  15. Operant Analysis of Intellectual Behavior in Old Age

    ERIC Educational Resources Information Center

    Labouvie-Vief, G.; And Others

    1974-01-01

    Proposes an operant framework for the analysis of environment-intelligence interactions in old age and calls for an implementation of research aimed at examining the range of modifiability of intellectual proficiency in the elderly. Intellectual decrement is interpreted to reflect the lack of supportive environmental contingencies. (Author/SDH)

  16. Sex Differences in the Play Behavior of Three Age Groups.

    ERIC Educational Resources Information Center

    Clance, Pauline Rose; And Others

    Erik Erikson concluded that differences in the play constructions of young children are largely determined by psychosexual differences in the subjects and not by cultural influence. He suggested that additional observation of younger and older subjects could determine whether the differences were true for all ages or whether they were restricted…

  17. Grape juice, berries and walnuts affect brain aging and behavior

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Numerous studies have indicated that individuals consuming a diet containing high amounts of fruits and vegetables exhibit fewer age-related diseases such as Alzheimer Disease (AD). A recent report has indicated that individuals who consumed a diet containing 2.5 servings of fruit and vegetables/day...

  18. Effects of age and experience on contest behavior in the burying beetle, Nicrophorus vespilloides.

    PubMed

    Lee, Victoria E; Head, Megan L; Carter, Mauricio J; Royle, Nick J

    2014-01-01

    Contest behavior forms an important part of reproductive investment. Life-history theory predicts that as individuals age and their residual reproductive value decreases, they should increase investment in contest behavior. However, other factors such as social experience may also be important in determining age-related variation in contest behavior. To understand how selection acts on contest behavior over an individual's lifetime, it is therefore important to tease apart the effects of age per se from other factors that may vary with age. Here, we independently manipulate male age and social experience to examine their effects on male contest behavior in the burying beetle Nicrophorus vespilloides. We found that social experience, but not age, influenced male contest behavior but that these changes in behavior did not alter contest outcomes. Male size (relative to his opponent) was overwhelmingly the most important factor determining contest outcome. Our results suggest that in systems with high variation in fighting ability among males, there may be little opportunity for selection to act on factors that influence contest outcomes by altering motivation to win.

  19. Effects of Aging on Experimentally Instructed Detached Reappraisal, Positive Reappraisal, and Emotional Behavior Suppression

    PubMed Central

    Shiota, Michelle N.; Levenson, Robert W.

    2009-01-01

    Emotion regulation includes multiple strategies that rely upon different underlying abilities, and that may be affected differently by aging. We assessed young, middle-aged, and older adults' ability to implement three emotion regulation strategies (detached reappraisal, positive reappraisal, and behavior suppression) in a laboratory setting, using standardized emotional stimuli and a multi-method approach to assessing regulation success. Results revealed age-related decline in ability to implement detached reappraisal, enhancement of ability to implement positive reappraisal, and maintenance of ability to implement behavior suppression. We discuss these findings in terms of their implications for emotion theory and for promoting successful aging. PMID:20025404

  20. Effects of moderate prenatal ethanol exposure and age on social behavior, spatial response perseveration errors and motor behavior.

    PubMed

    Hamilton, Derek A; Barto, Daniel; Rodriguez, Carlos I; Magcalas, Christy M; Fink, Brandi C; Rice, James P; Bird, Clark W; Davies, Suzy; Savage, Daniel D

    2014-08-01

    Persistent deficits in social behavior are among the major negative consequences associated with exposure to ethanol during prenatal development. Prior work from our laboratory has linked deficits in social behavior following moderate prenatal alcohol exposure (PAE) in the rat to functional alterations in the ventrolateral frontal cortex [21]. In addition to social behaviors, the regions comprising the ventrolateral frontal cortex are critical for diverse processes ranging from orofacial motor movements to flexible alteration of behavior in the face of changing consequences. The broader behavioral implications of altered ventrolateral frontal cortex function following moderate PAE have, however, not been examined. In the present study we evaluated the consequences of moderate PAE on social behavior, tongue protrusion, and flexibility in a variant of the Morris water task that required modification of a well-established spatial response. PAE rats displayed deficits in tongue protrusion, reduced flexibility in the spatial domain, increased wrestling, and decreased investigation, indicating that several behaviors associated with ventrolateral frontal cortex function are impaired following moderate PAE. A linear discriminant analysis revealed that measures of wrestling and tongue protrusion provided the best discrimination of PAE rats from saccharin-exposed control rats. We also evaluated all behaviors in young adult (4-5 months) or older (10-11 months) rats to address the persistence of behavioral deficits in adulthood and possible interactions between early ethanol exposure and advancing age. Behavioral deficits in each domain persisted well into adulthood (10-11 months), however, there was no evidence that aging enhances the effects of moderate PAE within the age ranges that were studied. PMID:24769174

  1. Aging and Autophagic Function Influences the Progressive Decline of Adult Drosophila Behaviors

    PubMed Central

    Kotzebue, Roxanne W.; Gonzalez, Arysa; Achal, Madhulika; Barekat, Ayeh; Finley, Kaelyn A.; Sparhawk, Jonathan M.; Robinson, James E.; Herr, Deron R.; Harris, Greg L.; Joiner, William J.; Finley, Kim D.

    2015-01-01

    Multiple neurological disorders are characterized by the abnormal accumulation of protein aggregates and the progressive impairment of complex behaviors. Our Drosophila studies demonstrate that middle-aged wild-type flies (WT, ~4-weeks) exhibit a marked accumulation of neural aggregates that is commensurate with the decline of the autophagy pathway. However, enhancing autophagy via neuronal over-expression of Atg8a (Atg8a-OE) reduces the age-dependent accumulation of aggregates. Here we assess basal locomotor activity profiles for single- and group-housed male and female WT flies and observed that only modest behavioral changes occurred by 4-weeks of age, with the noted exception of group-housed male flies. Male flies in same-sex social groups exhibit a progressive increase in nighttime activity. Infrared videos show aged group-housed males (4-weeks) are engaged in extensive bouts of courtship during periods of darkness, which is partly repressed during lighted conditions. Together, these nighttime courtship behaviors were nearly absent in young WT flies and aged Atg8a-OE flies. Previous studies have indicated a regulatory role for olfaction in male courtship partner choice. Coincidently, the mRNA expression profiles of several olfactory genes decline with age in WT flies; however, they are maintained in age-matched Atg8a-OE flies. Together, these results suggest that middle-aged male flies develop impairments in olfaction, which could contribute to the dysregulation of courtship behaviors during dark time periods. Combined, our results demonstrate that as Drosophila age, they develop early behavior defects that are coordinate with protein aggregate accumulation in the nervous system. In addition, the nighttime activity behavior is preserved when neuronal autophagy is maintained (Atg8a-OE flies). Thus, environmental or genetic factors that modify autophagic capacity could have a positive impact on neuronal aging and complex behaviors. PMID:26182057

  2. Marriage behavior response to prime-age adult mortality: evidence from Malawi.

    PubMed

    Ueyama, Mika; Yamauchi, Futoshi

    2009-02-01

    This article examines the effect of AIDS-related mortality of the prime-age adult population on marriage behavior among women in Malawi. A rise in prime-age adult mortality increases risks associated with the search for a marriage partner in the marriage market. A possible behavioral change in the marriage market in response to an increase in prime-age adult mortality is to marry earlier to avoid exposure to HIV/AIDS risks. We test this hypothesis by using micro data from Malawi, where prime-age adult mortality has drastically increased. In the analysis, we estimate the probability of prime-age adult mortality that sample women have observed during their adolescent period by utilizing retrospective information on deaths of their siblings. Empirical analysis shows that excess prime-age adult mortality in the local marriage market lowers the marriage age for females and shortens the interval between the first sex and first marriage.

  3. Behavioral effects of basal forebrain cholinergic lesions in young adult and aging rats.

    PubMed

    Paban, Véronique; Chambon, Caroline; Jaffard, Magali; Alescio-Lautier, Béatrice

    2005-08-01

    The interactive effects of age and cholinergic damage were assessed behaviorally in young and middle-aged rats. Rats were lesioned at either 3 or 17 months of age by injection of 192 IgG-saporin immunotoxin into the medial septum and the nucleus basalis magnocellularis, and they were then tested on a range of behavioral tasks: a nonmatching-to-position task in a T-maze, an object-recognition task, an object-location task, and an open-field activity test. Depending on the task used, only an age or a lesion effect was observed, but there was no Age X Lesion interaction. Middle-aged and young rats responded to the cholinergic lesions in the same manner. These results show that in the middle-aged rats in which cholinergic transmission was affected, additional injury to the system was not always accompanied by major cognitive dysfunctions. PMID:16187821

  4. Behavior of Fe-ODS Alloys After Thermal Aging Treatments

    NASA Astrophysics Data System (ADS)

    Serrano Garcia, Marta; Hernández-Mayoral, Mercedes; Esparraguera, Elvira Oñorbe

    2016-06-01

    Oxide dispersion alloys are one of the candidates as cladding materials for Gen IV fast reactors, due to their high strength at high temperature, good creep properties, and swelling resistance. This good performance is mainly due to a fine dispersion of nano-oxide particles on the microstructure and to non-grained structure. The microstructural stability and the mechanical properties of a Fe-ODS alloy are studied after different thermal aging experiments at 973 K (700 °C), 5000 hours; 973 K (700 °C), 10,000 hours; and 1123 K (850 °C), 10,000 hours. SEM/EBSD and TEM together with tensile and impact tests on the as-received and thermally aged material have been carried out. In general, for all the tested conditions, a slight softening effect is observed attributed to the changes in the grain structure as well as to the changes in the amount and size of nano-oxide particles. In addition, the aged material shows a lower impact USE value while the DBTT is maintained.

  5. Adrafinil: effects on behavior and cognition in aged canines.

    PubMed

    Siwak, C T; Callahan, H; Milgram, N W

    2000-07-01

    1. Adrafmil is a novel vigilance promoting agent developed in France by Louis Lafon Laboratories. 2. Adrafinil causes increased locomotion without producing stereotypical activity in canines tested in an open field. 3. The effectiveness of a single treatment is long-lasting, and the effectiveness persists over repeated treatments. 4. Acquisition of a size discrimination problem is enhanced by adrafinil. This may be linked to performance motivation. 5. Adrafinil causes a long-lasting increase in high frequency electroencephalographic activity recorded from cortical electrodes. 6. These results indicate that adrafinil is novel behavioral stimulant with cognitive enhancing potential. The underlying mechanisms of action are still unknown. PMID:11191710

  6. Dating age and stage as correlates of adolescent sexual attitudes and behavior.

    PubMed

    Miller, B C; Mccoy, J K; Olson, T D

    1986-01-01

    Dating experiences, especially the type or stage of dating, have consistently been found to be related to premarital sexual behavior. Findings regarding the age at 1st date and sexual behavior have been less consistent. This paper examined the age at which dating began and the type of dating relationship as correlates of premarital sexual attitudes and behavior among mid-teen adolescents. The analyses were based on a sample of high school students (n=836), most of whom were between the ages of 15 and 18 when the surveys were conducted. Early dating, especially early steady dating, was related to permissive attitudes and to premarital sexual experience among both males and females. The relationship between early dating and intercourse experience was particulary strong among Mormons, a religious group which has institutionalized age 16 as the legitimate age to begin dating. PMID:12341601

  7. Kids, candy, brain and behavior: age differences in responses to candy gains and losses.

    PubMed

    Luking, Katherine R; Luby, Joan L; Barch, Deanna M

    2014-07-01

    The development of reward-related neural systems, from adolescence through adulthood, has received much recent attention in the developmental neuroimaging literature. However, few studies have investigated behavioral and neural responses to both gains and losses in pre-pubertal child populations. To address this gap in the literature, in the present study healthy children aged 7-11 years and young-adults completed an fMRI card-guessing game using candy pieces delivered post-scan as an incentive. Age differences in behavioral and neural responses to candy gains/losses were investigated. Adults and children displayed similar responses to gains, but robust age differences were observed following candy losses within the caudate, thalamus, insula, and hippocampus. Interestingly, when task behavior was included as a factor in post hoc mediation analyses, activation following loss within the caudate/thalamus related to task behavior and relationships with age were no longer significant. Conversely, relationships between response to loss and age within the hippocampus and insula remained significant even when controlling for behavior, with children showing heightened loss responses within the dorsal/posterior insula. These results suggest that both age and task behavior influence responses within the extended reward circuitry, and that children seem to be more sensitive than adults to loss feedback particularly within the dorsal/posterior insula.

  8. An evaluation of the Aberrant Behavior Checklist for children under age 5.

    PubMed

    Schmidt, Jonathan D; Huete, John M; Fodstad, Jill C; Chin, Michelle D; Kurtz, Patricia F

    2013-04-01

    Severe problem behaviors such as self-injury and aggression are frequently observed in young children under age 5 with intellectual and developmental disabilities (IDD). Although early identification of problem behavior is critical to effective intervention, there are few standardized measures available that identify severe problem behavior in this population. The Aberrant Behavior Checklist-Community (ABC-C; Aman & Singh, 1994) is a rating scale that measures the severity of a range of problem behaviors commonly observed in individuals with IDD. While it has been used with children under 5, investigations into the fit of the ABC-C for this population are sparse. The purpose of the present study was to report on ABC-C scores in a sample of 97 children under age 5 with problem behavior. Analyses included evaluating differences in scores between age groups, comparing sample norms to established norms for older children, and conducting a confirmatory factor analysis. Results indicated differences in mean scores based on age with younger children generally scoring higher on some subscales of the ABC-C. Furthermore, the original 5-factor structure of the ABC-C was not fully supported. In general, the ABC-C may over- or underestimate behavior problems in younger children; therefore more extensive investigation into the utility of the ABC-C for children under age 5 is warranted.

  9. Age differences in the Attention Network Test: Evidence from behavior and event-related potentials.

    PubMed

    Williams, Ryan S; Biel, Anna Lena; Wegier, Pete; Lapp, Leann K; Dyson, Benjamin J; Spaniol, Julia

    2016-02-01

    The Attention Network Test (ANT) is widely used to capture group and individual differences in selective attention. Prior behavioral studies with younger and older adults have yielded mixed findings with respect to age differences in three putative attention networks (alerting, orienting, and executive control). To overcome the limitations of behavioral data, the current study combined behavioral and electrophysiological measures. Twenty-four healthy younger adults (aged 18-29years) and 24 healthy older adults (aged 60-76years) completed the ANT while EEG data were recorded. Behaviorally, older adults showed reduced alerting, but did not differ from younger adults in orienting or executive control. Electrophysiological components related to alerting and orienting (P1, N1, and CNV) were similar in both age groups, whereas components related to executive control (N2 and P3) showed age-related differences. Together these results suggest that comparisons of network effects between age groups using behavioral data alone may not offer a complete picture of age differences in selective attention, especially for alerting and executive control networks.

  10. Reducing the Noise in Behavioral Assays: Sex and Age in Adult Zebrafish Locomotion

    PubMed Central

    Philpott, Catelyn; Donack, Corey J.; Cousin, Margot A.

    2012-01-01

    Abstract Many assays are used in animal model systems to measure specific human disease-related behaviors. The use of both adult and larval zebrafish as a behavioral model is gaining popularity. As this work progresses and potentially translates into new treatments, we must do our best to improve the sensitivity of these assays by reducing confounding factors. Scientists who use the mouse model system have demonstrated that sex and age can influence a number of behaviors. As a community, they have moved to report the age and sex of all animals used in their studies. Zebrafish work does not yet carry the same mandate. In this study, we evaluated sex and age differences in locomotion behavior. We found that age was a significant factor in locomotion, as was sex within a given age group. In short, as zebrafish age, they appear to show less base level locomotion. With regard to sex, younger (10 months) zebrafish showed more locomotion in males, while older zebrafish (22 months) showed more movement in females. These findings have led us to suggest that those using the zebrafish for behavioral studies control for age and sex within their experimental design and report these descriptors in their methods. PMID:23244690

  11. Age differences in the Attention Network Test: Evidence from behavior and event-related potentials.

    PubMed

    Williams, Ryan S; Biel, Anna Lena; Wegier, Pete; Lapp, Leann K; Dyson, Benjamin J; Spaniol, Julia

    2016-02-01

    The Attention Network Test (ANT) is widely used to capture group and individual differences in selective attention. Prior behavioral studies with younger and older adults have yielded mixed findings with respect to age differences in three putative attention networks (alerting, orienting, and executive control). To overcome the limitations of behavioral data, the current study combined behavioral and electrophysiological measures. Twenty-four healthy younger adults (aged 18-29years) and 24 healthy older adults (aged 60-76years) completed the ANT while EEG data were recorded. Behaviorally, older adults showed reduced alerting, but did not differ from younger adults in orienting or executive control. Electrophysiological components related to alerting and orienting (P1, N1, and CNV) were similar in both age groups, whereas components related to executive control (N2 and P3) showed age-related differences. Together these results suggest that comparisons of network effects between age groups using behavioral data alone may not offer a complete picture of age differences in selective attention, especially for alerting and executive control networks. PMID:26760449

  12. Reducing the noise in behavioral assays: sex and age in adult zebrafish locomotion.

    PubMed

    Philpott, Catelyn; Donack, Corey J; Cousin, Margot A; Pierret, Chris

    2012-12-01

    Many assays are used in animal model systems to measure specific human disease-related behaviors. The use of both adult and larval zebrafish as a behavioral model is gaining popularity. As this work progresses and potentially translates into new treatments, we must do our best to improve the sensitivity of these assays by reducing confounding factors. Scientists who use the mouse model system have demonstrated that sex and age can influence a number of behaviors. As a community, they have moved to report the age and sex of all animals used in their studies. Zebrafish work does not yet carry the same mandate. In this study, we evaluated sex and age differences in locomotion behavior. We found that age was a significant factor in locomotion, as was sex within a given age group. In short, as zebrafish age, they appear to show less base level locomotion. With regard to sex, younger (10 months) zebrafish showed more locomotion in males, while older zebrafish (22 months) showed more movement in females. These findings have led us to suggest that those using the zebrafish for behavioral studies control for age and sex within their experimental design and report these descriptors in their methods.

  13. DISPERSION HARDENING OF URANIUM METAL

    DOEpatents

    Arbiter, W.

    1963-01-15

    A method of hardening U metal involves the forming of a fine dispersion of UO/sub 2/. This method consists of first hydriding the U to form a finely divided powder and then exposing the powder to a very dilute O gas in an inert atmosphere under such pressure and temperature conditions as to cause a thin oxide film to coat each particle of the U hydride, The oxide skin prevents agglomeration of the particles as the remaining H is removed, thus preserving the small particle size. The oxide skin coatings remain as an oxide dispersion. The resulting product may be workhardened to improve its physical characteristics. (AEC)

  14. Health Promoting Behaviors of Older Americans Versus Young and Middle Aged Adults

    ERIC Educational Resources Information Center

    Becker, Craig M.; Arnold, William

    2004-01-01

    Health promoting behaviors have become increasingly important as Americans attempt to retain their youth and health. This study collected self-reported data from 559 participants in the Southwest United States using the Health Promoting Lifestyle Profile II to compare the health promoting behaviors of older adults (60-92 years), middle-aged adults…

  15. Health Promoting Behaviors of Older Americans versus Young and Middle Aged Adults

    ERIC Educational Resources Information Center

    Becker, Craig; Arnold, William

    2004-01-01

    Health promoting behaviors have become increasingly important as Americans attempt to retain their youth and health. This study collected self-reported data from 559 participants in the Southwest United States using the Health Promoting Lifestyle Profile II to compare the health promoting behaviors of older adults (60-92 years), middle-aged adults…

  16. Pupillary behavior in relation to wavelength and age.

    PubMed

    Lobato-Rincón, Luis-Lucio; Cabanillas-Campos, Maria Del Carmen; Bonnin-Arias, Cristina; Chamorro-Gutiérrez, Eva; Murciano-Cespedosa, Antonio; Sánchez-Ramos Roda, Celia

    2014-01-01

    Pupil light reflex can be used as a non-invasive ocular predictor of cephalic autonomic nervous system integrity. Spectral sensitivity of the pupil's response to light has, for some time, been an interesting issue. It has generally, however, only been investigated with the use of white light and studies with monochromatic wavelengths are scarce. This study investigates the effects of wavelength and age within three parameters of the pupil light reflex (amplitude of response, latency, and velocity of constriction) in a large sample of younger and older adults (N = 97), in mesopic conditions. Subjects were exposed to a single light stimulus at four different wavelengths: white (5600°K), blue (450 nm), green (510 nm), and red (600 nm). Data was analyzed appropriately, and, when applicable, using the General Linear Model (GLM), Randomized Complete Block Design (RCBD), Student's t-test and/or ANCOVA. Across all subjects, pupillary response to light had the greatest amplitude and shortest latency in white and green light conditions. In regards to age, older subjects (46-78 years) showed an increased latency in white light and decreased velocity of constriction in green light compared to younger subjects (18-45 years old). This study provides data patterns on parameters of wavelength-dependent pupil reflexes to light in adults and it contributes to the large body of pupillometric research. It is hoped that this study will add to the overall evaluation of cephalic autonomic nervous system integrity. PMID:24795595

  17. Pupillary behavior in relation to wavelength and age

    PubMed Central

    Lobato-Rincón, Luis-Lucio; Cabanillas-Campos, Maria del Carmen; Bonnin-Arias, Cristina; Chamorro-Gutiérrez, Eva; Murciano-Cespedosa, Antonio; Sánchez-Ramos Roda, Celia

    2014-01-01

    Pupil light reflex can be used as a non-invasive ocular predictor of cephalic autonomic nervous system integrity. Spectral sensitivity of the pupil's response to light has, for some time, been an interesting issue. It has generally, however, only been investigated with the use of white light and studies with monochromatic wavelengths are scarce. This study investigates the effects of wavelength and age within three parameters of the pupil light reflex (amplitude of response, latency, and velocity of constriction) in a large sample of younger and older adults (N = 97), in mesopic conditions. Subjects were exposed to a single light stimulus at four different wavelengths: white (5600°K), blue (450 nm), green (510 nm), and red (600 nm). Data was analyzed appropriately, and, when applicable, using the General Linear Model (GLM), Randomized Complete Block Design (RCBD), Student's t-test and/or ANCOVA. Across all subjects, pupillary response to light had the greatest amplitude and shortest latency in white and green light conditions. In regards to age, older subjects (46–78 years) showed an increased latency in white light and decreased velocity of constriction in green light compared to younger subjects (18–45 years old). This study provides data patterns on parameters of wavelength-dependent pupil reflexes to light in adults and it contributes to the large body of pupillometric research. It is hoped that this study will add to the overall evaluation of cephalic autonomic nervous system integrity. PMID:24795595

  18. Radiation Hardened Electronics for Extreme Environments

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Watson, Michael D.

    2007-01-01

    The Radiation Hardened Electronics for Space Environments (RHESE) project consists of a series of tasks designed to develop and mature a broad spectrum of radiation hardened and low temperature electronics technologies. Three approaches are being taken to address radiation hardening: improved material hardness, design techniques to improve radiation tolerance, and software methods to improve radiation tolerance. Within these approaches various technology products are being addressed including Field Programmable Gate Arrays (FPGA), Field Programmable Analog Arrays (FPAA), MEMS Serial Processors, Reconfigurable Processors, and Parallel Processors. In addition to radiation hardening, low temperature extremes are addressed with a focus on material and design approaches.

  19. Energy-Efficient Thermomagnetic and Induction Hardening

    SciTech Connect

    2009-02-01

    This factsheet describes a research project that will develop and test a hybrid thermomagnetic and induction hardening technology to replace conventional heat treatment processes in forging applications.

  20. Differences in Affective and Behavioral Health-Related Variables Associated with Age.

    ERIC Educational Resources Information Center

    Bausell, R. Barker; Soeken, Karen L.

    Although considerable data exist linking individual lifestyle variables to health outcomes, little is known about how the elderly differ from younger adults with respect to both their health seeking behavior and their beliefs about health. A national survey contrasted 155 persons aged 65 years of age or older with 1100 younger adults in order to…

  1. Aging behavior of polymeric solar absorber materials - Part 1: Engineering plastics

    SciTech Connect

    Kahlen, S.; Wallner, G.M.; Lang, R.W.

    2010-09-15

    In this series of two papers, various polymeric materials are investigated as to their potential applicability as absorber materials for solar thermal collectors. The focus of the investigation is to study the aging behavior of these materials under maximum operating conditions (80 C in water up to 16,000 h) and stagnation conditions (140 C in air up to 500 h) typical for northern climate. The materials supplied or produced as polymer films were first characterized in the unaged state and then for different states of aging by differential scanning calorimetry (DSC), by size exclusion chromatography (SEC) and by mechanical tensile tests. Physical aging phenomena were studied by DSC, SEC analysis provided information on chemical degradation of the materials. In addition, physical and chemical aging were both analyzed via the small and large strain mechanical behavior. While the present Part 1 of this paper series deals with the aging behavior of engineering plastics, including two amorphous polymers (a polyphenylene ether polystyrene blend (PPE + PS) and polycarbonate (PC)) and two semi-crystalline polymers (two types of polyamide 12 (PA12)), the aging behavior of so-called ''commodity'' plastics (PE and PP) is the subject of Part 2. Comparing the two aging conditions, the amorphous materials (PPE + PS and PC) turned out to be more prone to physical and chemical aging at 140 C in air. In contrast, the semi-crystalline PA12 materials were more strongly affected by exposure to water at 80 C, although to different degrees, depending on the modification. (author)

  2. The Effects of Music on Age Group Swimmers' Motivation and Practice Behavior.

    ERIC Educational Resources Information Center

    Stoeckel, Bryan D.

    This study examined the effects of music on the motivation of 22 female and 5 male swimmers ages 10-13 years. These age-group swimmers practiced 2.0-2.5 hours per day and had six training sessions per week. Using observation logs, surveys, and open-ended questions, the study analyzed swimmers' perceptions of, and behavior when, listening to music…

  3. Attachment Style, Home-Leaving Age and Behavioral Problems among Residential Care Children

    ERIC Educational Resources Information Center

    Shechory, Mally; Sommerfeld, Eliane

    2007-01-01

    In a prospective study, the attachment style, home-leaving age, length of time in residential care, and behavioral problems among Israeli residential care children (N=68), were studied. Data analyses showed that children removed from their homes at a later age suffered from higher levels of anxiety, depression and social problems compared to…

  4. COSMIC-RAY HELIUM HARDENING

    SciTech Connect

    Ohira, Yutaka; Ioka, Kunihito

    2011-03-01

    Recent observations by the CREAM and ATIC-2 experiments suggest that (1) the spectrum of cosmic-ray (CR) helium is harder than that of CR protons below the knee energy, 10{sup 15}eV, and (2) all CR spectra become hard at {approx}>10{sup 11}eV nucleon{sup -1}. We propose a new idea, that higher energy CRs are generated in a more helium-rich region, to explain the hardening without introducing different sources for CR helium. The helium-to-proton ratio at {approx}100 TeV exceeds the Big Bang abundance Y = 0.25 by several times, and the different spectrum is not reproduced within the diffusive shock acceleration theory. We argue that CRs are produced in a chemically enriched region, such as a superbubble, and the outward-decreasing abundance naturally leads to the hard spectrum of CR helium if CRs escape from the supernova remnant shock in an energy-dependent way. We provide a simple analytical spectrum that also fits well the hardening due to the decreasing Mach number in the hot superbubble with {approx}10{sup 6} K. Our model predicts hard and concave spectra for heavier CR elements.

  5. Who Should Report Abnormal Behavior at Preschool Age? The Case of Behavioral Inhibition

    ERIC Educational Resources Information Center

    Ballespi, Sergi; Jane, Ma Claustre; Riba, Ma Dolors

    2012-01-01

    Children who are behaviorally "inhibited"--a condition at the extreme of the behavioral inhibition dimension--experience distress in uncertain social situations. Although parents and teachers are in the best position to detect this condition, they rarely agree. This study aims to analyze the agreement between parents and teachers and to examine…

  6. Reading Instruction for Elementary-Age Students with Emotional and Behavioral Disorders: Academic and Behavioral Outcomes

    ERIC Educational Resources Information Center

    Barton-Arwood, Sally M.; Wehby, Joseph H.; Falk, Katherine B.

    2005-01-01

    This study evaluated the effects of a reading intervention on the reading achievement and social behaviors of 6 third-grade students with emotional/behavioral disorders. Reading instruction occurred 4 days a week using the Horizons Fast Track reading program and Peer-Assisted Learning Strategies. Analyses indicated variable improvements in basic…

  7. Aging and the Effects of Exploratory Behavior on Spatial Memory.

    PubMed

    Varner, Kaitlin M; Dopkins, Stephen; Philbeck, John W

    2016-03-01

    The present research examined the effect of encoding from multiple viewpoints on scene recall in a group of younger (18-22 years) and older (65-80 years) adults. Participants completed a visual search task, during which they were given the opportunity to examine a room using two sets of windows that partitioned the room differently. Their choice of window set was recorded, to determine whether an association between these choices and spatial memory performance existed. Subsequently, participants were tested for spatial memory of the domain in which the search task was completed. Relative to younger adults, older adults demonstrated an increased tendency to use a single set of windows as well as decreased spatial memory for the domain. Window-set usage was associated with spatial memory, such that older adults who relied more heavily on a single set of windows also had better performance on the spatial memory task. These findings suggest that, in older adults, moderation in exploratory behavior may have a positive effect on memory for the domain of exploration.

  8. The evolution of oscillatory behavior in age-structured species.

    PubMed

    Greenman, J V; Benton, T G; Boots, M; White, A R

    2005-07-01

    A major challenge in ecology is to explain why so many species show oscillatory population dynamics and why the oscillations commonly occur with particular periods. The background environment, through noise or seasonality, is one possible driver of these oscillations, as are the components of the trophic web with which the species interacts. However, the oscillation may also be intrinsic, generated by density-dependent effects on the life history. Models of structured single-species systems indicate that a much broader range of oscillatory behavior than that seen in nature is theoretically possible. We test the hypothesis that it is selection that acts to constrain the range of periods. We analyze a nonlinear single-species matrix model with density dependence affecting reproduction and with trade-offs between reproduction and survival. We show that the evolutionarily stable state is oscillatory and has a period roughly twice the time to maturation, in line with observed patterns of periodicity. The robustness of this result to variations in trade-off function and density dependence is tested.

  9. The Predictive Utility of Early Childhood Disruptive Behaviors for School-Age Social Functioning

    PubMed Central

    Shaw, Daniel S.; Dishion, Thomas J.; Wilson, Melvin N.

    2016-01-01

    Research suggests that school-age children with disruptive behavior (DB) problems frequently demonstrate impaired social skills and experience rejection from peers, which plays a crucial role in the pathway to more serious antisocial behavior. A critical question is which DB problems in early childhood are prognostic of impaired social functioning in school-age children. This study examines the hypothesis that aggression in early childhood will be the more consistent predictor of compromised social functioning than inattentive, hyperactive-impulsive, or oppositional behavior. Participants included an ethnically diverse sample of 725 high-risk children from 3 geographically distinct areas followed from ages 2 to 8.5. Four latent growth models of DB from child ages 2 to 5, and potential interactions between dimensions, were used to predict latent parent and teacher ratings of school-age social dysfunction. Analyses were conducted in a multi-group format to examine potential differences between intervention and control group participants. Results showed that age 2 aggression was the DB problem most consistently associated with both parent- and teacher-rated social dysfunction for both groups. Early starting aggressive behavior may be particularly important for the early identification of children at risk for school-age social difficulties. PMID:25526865

  10. On the Precipitation Hardening of Selective Laser Melted AlSi10Mg

    NASA Astrophysics Data System (ADS)

    Aboulkhair, Nesma T.; Tuck, Chris; Ashcroft, Ian; Maskery, Ian; Everitt, Nicola M.

    2015-08-01

    Precipitation hardening of selective laser melted AlSi10Mg was investigated in terms of solution heat treatment and aging duration. The influence on the microstructure and hardness was established, as was the effect on the size and density of Si particles. Although the hardness changes according to the treatment duration, the maximum hardening effect falls short of the hardness of the as-built parts with their characteristic fine microstructure. This is due to the difference in strengthening mechanisms.

  11. Improved hardening theory for cyclic plasticity.

    NASA Technical Reports Server (NTRS)

    Vos, R. G.; Armstrong, W. H.

    1973-01-01

    A temperature-dependent version of a combined hardening theory, including isotropic and kinematic hardening, is presented within the framework of recent plasticity formulations. This theory has been found to be especially useful in finite-element analysis of aerospace vehicle engines under conditions of large plastic strain and low-cycle fatigue.

  12. A vulnerable age: environment, behavior and the spread of diarrhoea.

    PubMed

    1986-09-01

    In Bangladesh diarrhea occurs most often in children between the ages of 6-11 months. Crawling infants in rural areas come into contact with chicken feces and other animal dung on the ground both inside and outside the home. Additionally, the ground is contaminated with the baby's own feces and those of its brothers and sisters. Many infants put earth and feces in their mouths and most suck their fingers, which have touched and will pass on germs and fecal matter. Infants in 2 villages near Dhaka were found to have high rates of illness and malnutrition. Those whose families were poor and did not own land were affected more severely; they had worse malnutrition and a higher incidence of diarrhea. In both villages most infants were put down to play for most of the day. Most mothers said they rarely or never put a mat or jute sack down for their baby to lie on or crawl around on, and only a third of mothers were able to watch their babies continuously. The ground on which these infants were crawling was found to be highly contaminated. It was learned that while most mothers knew that feces were dirty, they were unaware that feces can cause disease. Poor traditional weaning practices and poor food hygiene also contributed to high attack rates of diarrhea. Basic messages and a range of interventions to improve traditional hygiene and health care practices were developed. First, mothers need to understand about germs and the fact that these cause diseases. Local materials and ideas were used to demonstrate this to a mainly illiterate audience. Interventions to keep the baby from touching and eating feces include: sweeping the baby's play area 4 times a day; using a dirt disposer, like a trowel, to remove feces from the ground; using a covered pit or latrine to dispose of feces; using a special place for disposing of garbage; and keeping crawling infants in a playpen. Interventions to reduce transmission of germs include: washing hands with ashes or soap after defecating

  13. A vulnerable age: environment, behavior and the spread of diarrhoea.

    PubMed

    1986-09-01

    In Bangladesh diarrhea occurs most often in children between the ages of 6-11 months. Crawling infants in rural areas come into contact with chicken feces and other animal dung on the ground both inside and outside the home. Additionally, the ground is contaminated with the baby's own feces and those of its brothers and sisters. Many infants put earth and feces in their mouths and most suck their fingers, which have touched and will pass on germs and fecal matter. Infants in 2 villages near Dhaka were found to have high rates of illness and malnutrition. Those whose families were poor and did not own land were affected more severely; they had worse malnutrition and a higher incidence of diarrhea. In both villages most infants were put down to play for most of the day. Most mothers said they rarely or never put a mat or jute sack down for their baby to lie on or crawl around on, and only a third of mothers were able to watch their babies continuously. The ground on which these infants were crawling was found to be highly contaminated. It was learned that while most mothers knew that feces were dirty, they were unaware that feces can cause disease. Poor traditional weaning practices and poor food hygiene also contributed to high attack rates of diarrhea. Basic messages and a range of interventions to improve traditional hygiene and health care practices were developed. First, mothers need to understand about germs and the fact that these cause diseases. Local materials and ideas were used to demonstrate this to a mainly illiterate audience. Interventions to keep the baby from touching and eating feces include: sweeping the baby's play area 4 times a day; using a dirt disposer, like a trowel, to remove feces from the ground; using a covered pit or latrine to dispose of feces; using a special place for disposing of garbage; and keeping crawling infants in a playpen. Interventions to reduce transmission of germs include: washing hands with ashes or soap after defecating

  14. Homeostatic and injury-induced microglia behavior in the aging brain

    PubMed Central

    Hefendehl, Jasmin K; Neher, Jonas J; Sühs, Rafael B; Kohsaka, Shinichi; Skodras, Angelos; Jucker, Mathias

    2014-01-01

    Microglia cells are essential for brain homeostasis and have essential roles in neurodegenerative diseases. Aging is the main risk factor for most neurodegenerative diseases, and age-related changes in microglia may contribute to the susceptibility of the aging brain to dysfunction and neurodegeneration. We have analyzed morphology and dynamic behavior of neocortical microglia in their physiological environment in young adult (3-month-old), adult (11- to 12-month-old), and aged (26- to 27-month-old) C57BL/6J-Iba1-eGFP mice using in vivo 2-photon microscopy. Results show that surveying microglial cells in the neocortex exhibit age-related soma volume increase, shortening of processes, and loss of homogeneous tissue distribution. Furthermore, microglial process speed significantly decreased with age. While only a small population of microglia showed soma movement in adult mice, the microglia population with soma movement was increased in aged mice. However, in response to tissue injury, the dynamic microglial response was age-dependently diminished. These results provide novel insights into microglial behavior and indicate that microglial dysfunction in the aging brain may contribute to age-related cognitive decline and neurodegenerative diseases. PMID:23953759

  15. Aging behavior of polymeric solar absorber materials - Part 2: Commodity plastics

    SciTech Connect

    Kahlen, S.; Wallner, G.M.; Lang, R.W.

    2010-09-15

    In this series of two papers, various polymeric materials are investigated as to their potential applicability as absorber materials for solar thermal collectors. While Part 1 of this paper series deals with the aging behavior of engineering plastics, including two amorphous polymers (PPE + PS) and (PC) and two semi-crystalline polymers (two types of PA12), the present Part 2 treats the aging behavior of semi-crystalline so-called ''commodity'' plastics (two types of crosslinked polyethylene (PE-X) and two types of polypropylene (PP)). As in Part 1, the focus of the investigation is to study the aging behavior of these materials under maximum operating conditions (80 C in water up to 16,000 h) and stagnation conditions (140 C in air up to 500 h) typical for northern climate. The materials supplied or produced as polymer films were first characterized in the unaged state and then for different states of aging by differential scanning calorimetry (DSC), by size exclusion chromatography (SEC) and by mechanical tensile tests. DSC was applied primarily to obtain information on physical aging phenomena, whereas SEC analysis was used to characterize chemical degradation of the materials. In addition, physical and chemical aging were both analyzed via the small and large strain mechanical behavior. Comparing the two aging conditions in hot air and hot water, a rather stable mechanical performance profile was found for both PP types over the investigated aging time, which was interpreted in terms of competing physical and chemical aging mechanisms. Analogously such competing mechanisms were also inferred for one of the PE-X materials, while the other exhibited substantial degradation in terms of strain-to-break values for both aging conditions. In principle, both PP and PE-X are promising candidates for black absorber applications in northern climates if proper measures against overheating are taken and when adequately modified. (author)

  16. Age-related striatal BOLD changes without changes in behavioral loss aversion

    PubMed Central

    Viswanathan, Vijay; Lee, Sang; Gilman, Jodi M.; Kim, Byoung Woo; Lee, Nick; Chamberlain, Laura; Livengood, Sherri L.; Raman, Kalyan; Lee, Myung Joo; Kuster, Jake; Stern, Daniel B.; Calder, Bobby; Mulhern, Frank J.; Blood, Anne J.; Breiter, Hans C.

    2015-01-01

    Loss aversion (LA), the idea that negative valuations have a higher psychological impact than positive ones, is considered an important variable in consumer research. The literature on aging and behavior suggests older individuals may show more LA, although it is not clear if this is an effect of aging in general (as in the continuum from age 20 and 50 years), or of the state of older age (e.g., past age 65 years). We also have not yet identified the potential biological effects of aging on the neural processing of LA. In the current study we used a cohort of subjects with a 30 year range of ages, and performed whole brain functional MRI (fMRI) to examine the ventral striatum/nucleus accumbens (VS/NAc) response during a passive viewing of affective faces with model-based fMRI analysis incorporating behavioral data from a validated approach/avoidance task with the same stimuli. Our a priori focus on the VS/NAc was based on (1) the VS/NAc being a central region for reward/aversion processing; (2) its activation to both positive and negative stimuli; (3) its reported involvement with tracking LA. LA from approach/avoidance to affective faces showed excellent fidelity to published measures of LA. Imaging results were then compared to the behavioral measure of LA using the same affective faces. Although there was no relationship between age and LA, we observed increasing neural differential sensitivity (NDS) of the VS/NAc to avoidance responses (negative valuations) relative to approach responses (positive valuations) with increasing age. These findings suggest that a central region for reward/aversion processing changes with age, and may require more activation to produce the same LA behavior as in younger individuals, consistent with the idea of neural efficiency observed with high IQ individuals showing less brain activation to complete the same task. PMID:25983682

  17. Age-related striatal BOLD changes without changes in behavioral loss aversion.

    PubMed

    Viswanathan, Vijay; Lee, Sang; Gilman, Jodi M; Kim, Byoung Woo; Lee, Nick; Chamberlain, Laura; Livengood, Sherri L; Raman, Kalyan; Lee, Myung Joo; Kuster, Jake; Stern, Daniel B; Calder, Bobby; Mulhern, Frank J; Blood, Anne J; Breiter, Hans C

    2015-01-01

    Loss aversion (LA), the idea that negative valuations have a higher psychological impact than positive ones, is considered an important variable in consumer research. The literature on aging and behavior suggests older individuals may show more LA, although it is not clear if this is an effect of aging in general (as in the continuum from age 20 and 50 years), or of the state of older age (e.g., past age 65 years). We also have not yet identified the potential biological effects of aging on the neural processing of LA. In the current study we used a cohort of subjects with a 30 year range of ages, and performed whole brain functional MRI (fMRI) to examine the ventral striatum/nucleus accumbens (VS/NAc) response during a passive viewing of affective faces with model-based fMRI analysis incorporating behavioral data from a validated approach/avoidance task with the same stimuli. Our a priori focus on the VS/NAc was based on (1) the VS/NAc being a central region for reward/aversion processing; (2) its activation to both positive and negative stimuli; (3) its reported involvement with tracking LA. LA from approach/avoidance to affective faces showed excellent fidelity to published measures of LA. Imaging results were then compared to the behavioral measure of LA using the same affective faces. Although there was no relationship between age and LA, we observed increasing neural differential sensitivity (NDS) of the VS/NAc to avoidance responses (negative valuations) relative to approach responses (positive valuations) with increasing age. These findings suggest that a central region for reward/aversion processing changes with age, and may require more activation to produce the same LA behavior as in younger individuals, consistent with the idea of neural efficiency observed with high IQ individuals showing less brain activation to complete the same task.

  18. Age-related striatal BOLD changes without changes in behavioral loss aversion.

    PubMed

    Viswanathan, Vijay; Lee, Sang; Gilman, Jodi M; Kim, Byoung Woo; Lee, Nick; Chamberlain, Laura; Livengood, Sherri L; Raman, Kalyan; Lee, Myung Joo; Kuster, Jake; Stern, Daniel B; Calder, Bobby; Mulhern, Frank J; Blood, Anne J; Breiter, Hans C

    2015-01-01

    Loss aversion (LA), the idea that negative valuations have a higher psychological impact than positive ones, is considered an important variable in consumer research. The literature on aging and behavior suggests older individuals may show more LA, although it is not clear if this is an effect of aging in general (as in the continuum from age 20 and 50 years), or of the state of older age (e.g., past age 65 years). We also have not yet identified the potential biological effects of aging on the neural processing of LA. In the current study we used a cohort of subjects with a 30 year range of ages, and performed whole brain functional MRI (fMRI) to examine the ventral striatum/nucleus accumbens (VS/NAc) response during a passive viewing of affective faces with model-based fMRI analysis incorporating behavioral data from a validated approach/avoidance task with the same stimuli. Our a priori focus on the VS/NAc was based on (1) the VS/NAc being a central region for reward/aversion processing; (2) its activation to both positive and negative stimuli; (3) its reported involvement with tracking LA. LA from approach/avoidance to affective faces showed excellent fidelity to published measures of LA. Imaging results were then compared to the behavioral measure of LA using the same affective faces. Although there was no relationship between age and LA, we observed increasing neural differential sensitivity (NDS) of the VS/NAc to avoidance responses (negative valuations) relative to approach responses (positive valuations) with increasing age. These findings suggest that a central region for reward/aversion processing changes with age, and may require more activation to produce the same LA behavior as in younger individuals, consistent with the idea of neural efficiency observed with high IQ individuals showing less brain activation to complete the same task. PMID:25983682

  19. Age and sex influence marmot antipredator behavior during periods of heightened risk.

    PubMed

    Lea, Amanda J; Blumstein, Daniel T

    2011-08-01

    Animals adjust their antipredator behavior according to environmental variation in risk, and to account for their ability to respond to threats. Intrinsic factors that influence an animal's ability to respond to predators (e.g., age, body condition) should explain variation in antipredator behavior. For example, a juvenile might allocate more time to vigilance than an adult because mortality as a result of predation is often high for this age class; however, the relationship between age/vulnerability and antipredator behavior is not always clear or as predicted. We explored the influence of intrinsic factors on yellow-bellied marmot (Marmota flaviventris) antipredator behavior using data pooled from 4 years of experiments. We hypothesized that inherently vulnerable animals (e.g., young, males, and individuals in poor condition) would exhibit more antipredator behavior prior to and immediately following conspecific alarm calls. As expected, males and yearlings suppressed foraging more than females and adults following alarm call playbacks. In contrast to predictions, animals in better condition respond more than animals in below average condition. Interestingly, these intrinsic properties did not influence baseline time budgets; animals of all ages, sexes, and condition levels devoted comparable amounts of time to foraging prior to alarm calls. Our results support the hypothesis that inherent differences in vulnerability influence antipredator behavior; furthermore, it appears that a crucial, but poorly acknowledged, interaction exists between risk and state-dependence. Elevated risk may be required to reveal the workings of state-dependent behavior, and studies of antipredator behavior in a single context may draw incomplete conclusions about age- or sex-specific strategies.

  20. Effect of geometry on thermal aging behavior of Celion/LARC-160 composites

    NASA Technical Reports Server (NTRS)

    Nelson, James B.

    1987-01-01

    Laminates of Celion/LARC-160, fabricated in thicknesses from 4 to 16 ply and in unidirectional, x-ply and fabric ply configurations, were isothermally aged at temperatures of 204, 260 and 316 C for periods up to 15,000 hours. Weight-loss of the test panels was measured at selected intervals during aging. At the lower aging temperatures, it was observed that panel thickness and ply arrangement influenced the apparent stability: i.e., thicker panels degraded less than thin panels and unidirectional panels degraded less than x-ply or fabric reinforced panels. At higher aging temperatures, all panel configurations and thicknesses converged toward the same behavior.

  1. Natural aging and reversion behavior of Al-Cu-Li-Ag-Mg alloy Weldalite (tm) 049

    NASA Technical Reports Server (NTRS)

    Gayle, Frank W.; Heubaum, Frank H.; Pickens, Joseph R.

    1991-01-01

    This study was initiated to understand the natural aging and reversion behavior of Weldalite (trademark) 049 in tempers without cold work. Of particular interest are: (1) the microstructural basis for the high strength in the T4 condition; (2) an explanation of the reversion phenomenon; and (3) the effect of re-aging at room temperature after a reversion treatment. Mechanical properties were measured and transmission electron microscopy (TEM) analysis performed at various stages of microstructural development during aging, reversion, and subsequent re-aging.

  2. Iron Supplementation in Infancy Contributes to More Adaptive Behavior at 10 Years of Age1234

    PubMed Central

    Lozoff, Betsy; Castillo, Marcela; Clark, Katy M.; Smith, Julia B.; Sturza, Julie

    2014-01-01

    Most studies of behavioral/developmental effects of iron deficiency anemia (IDA) or iron supplementation in infancy have found social-emotional differences. Differences could relate to behavioral inhibition or lack of positive affect and altered response to reward. To determine long-term behavioral effects, the study was a follow-up of a randomized controlled trial of behavioral/developmental effects of preventing IDA in infancy. Healthy Chilean infants free of IDA at age 6 mo were randomly assigned to iron supplementation or no added iron (formula with iron/powdered cow milk, vitamins with/without iron) from ages 6 to 12 mo. At age 10 y, 59% (666 of 1123) and 68% (366 of 534) of iron-supplemented and no-added-iron groups were assessed. Social-emotional outcomes included maternal-reported behavior problems, self-reported behavior, examiner ratings, and video coding of a social stress task and gamelike paradigms. Examiners rated the iron-supplemented group as more cooperative, confident, persistent after failure, coordinated, and direct and reality-oriented in speech and working harder after praise compared with the no-added-iron group. In a task designed to elicit positive affect, supplemented children spent more time laughing and smiling together with their mothers and started smiling more quickly. In the social stress task they smiled and laughed more and needed less prompting to complete the task. All P values were <0.05; effect sizes were 0.14–0.36. There were no differences in behaviors related to behavioral inhibition, such as anxiety/depression or social problems. In sum, iron supplementation in infancy was associated with more adaptive behavior at age 10 y, especially in affect and response to reward, which may improve performance at school and work, mental health, and personal relationships. PMID:24717366

  3. Iron supplementation in infancy contributes to more adaptive behavior at 10 years of age.

    PubMed

    Lozoff, Betsy; Castillo, Marcela; Clark, Katy M; Smith, Julia B; Sturza, Julie

    2014-06-01

    Most studies of behavioral/developmental effects of iron deficiency anemia (IDA) or iron supplementation in infancy have found social-emotional differences. Differences could relate to behavioral inhibition or lack of positive affect and altered response to reward. To determine long-term behavioral effects, the study was a follow-up of a randomized controlled trial of behavioral/developmental effects of preventing IDA in infancy. Healthy Chilean infants free of IDA at age 6 mo were randomly assigned to iron supplementation or no added iron (formula with iron/powdered cow milk, vitamins with/without iron) from ages 6 to 12 mo. At age 10 y, 59% (666 of 1123) and 68% (366 of 534) of iron-supplemented and no-added-iron groups were assessed. Social-emotional outcomes included maternal-reported behavior problems, self-reported behavior, examiner ratings, and video coding of a social stress task and gamelike paradigms. Examiners rated the iron-supplemented group as more cooperative, confident, persistent after failure, coordinated, and direct and reality-oriented in speech and working harder after praise compared with the no-added-iron group. In a task designed to elicit positive affect, supplemented children spent more time laughing and smiling together with their mothers and started smiling more quickly. In the social stress task they smiled and laughed more and needed less prompting to complete the task. All P values were <0.05; effect sizes were 0.14-0.36. There were no differences in behaviors related to behavioral inhibition, such as anxiety/depression or social problems. In sum, iron supplementation in infancy was associated with more adaptive behavior at age 10 y, especially in affect and response to reward, which may improve performance at school and work, mental health, and personal relationships.

  4. Iron supplementation in infancy contributes to more adaptive behavior at 10 years of age.

    PubMed

    Lozoff, Betsy; Castillo, Marcela; Clark, Katy M; Smith, Julia B; Sturza, Julie

    2014-06-01

    Most studies of behavioral/developmental effects of iron deficiency anemia (IDA) or iron supplementation in infancy have found social-emotional differences. Differences could relate to behavioral inhibition or lack of positive affect and altered response to reward. To determine long-term behavioral effects, the study was a follow-up of a randomized controlled trial of behavioral/developmental effects of preventing IDA in infancy. Healthy Chilean infants free of IDA at age 6 mo were randomly assigned to iron supplementation or no added iron (formula with iron/powdered cow milk, vitamins with/without iron) from ages 6 to 12 mo. At age 10 y, 59% (666 of 1123) and 68% (366 of 534) of iron-supplemented and no-added-iron groups were assessed. Social-emotional outcomes included maternal-reported behavior problems, self-reported behavior, examiner ratings, and video coding of a social stress task and gamelike paradigms. Examiners rated the iron-supplemented group as more cooperative, confident, persistent after failure, coordinated, and direct and reality-oriented in speech and working harder after praise compared with the no-added-iron group. In a task designed to elicit positive affect, supplemented children spent more time laughing and smiling together with their mothers and started smiling more quickly. In the social stress task they smiled and laughed more and needed less prompting to complete the task. All P values were <0.05; effect sizes were 0.14-0.36. There were no differences in behaviors related to behavioral inhibition, such as anxiety/depression or social problems. In sum, iron supplementation in infancy was associated with more adaptive behavior at age 10 y, especially in affect and response to reward, which may improve performance at school and work, mental health, and personal relationships. PMID:24717366

  5. CMOS inverter design-hardened to the total dose effect

    SciTech Connect

    Roche, F.M.; Salager, L.

    1996-12-01

    This paper reports and discusses the experimental behavior of two inverter structures Rad-Hardened by Design to {sup 60}Co irradiation. The authors use the results on a set of basic circuits and transistors exposed to the same total doses as these structures to establish the effective formation conditions of the parasitic channel. Then this leakage evolution is related to the gate voltage history under irradiation. Finally, they take advantage of this intrinsic degradation property to propose a new Design Rad Hardened (DRH) cell. This structure considerably limits the Low Noise Margin degradation, helps to maintain the logic functionality with a High Output level and improves both the rad-tolerance and the static power consumption.

  6. Cracking behavior of thermally aged and irradiated CF-8 cast austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Alexandreanu, B.; Chen, W.-Y.; Natesan, K.; Li, Z.; Yang, Y.; Rao, A. S.

    2015-11-01

    To assess the combined effect of thermal aging and neutron irradiation on the cracking behavior of CF-8 cast austenitic stainless steel, crack growth rate (CGR) and fracture toughness J-R curve tests were carried out on compact-tension specimens in high-purity water with low dissolved oxygen. Both unaged and thermally aged specimens were irradiated at ∼320 °C to 0.08 dpa. Thermal aging at 400 °C for 10,000 h apparently had no effect on the corrosion fatigue and stress corrosion cracking behavior in the test environment. The cracking susceptibility of CF-8 was not elevated significantly by neutron irradiation at 0.08 dpa. Transgranular cleavage-like cracking was the main fracture mode during the CGR tests, and a brittle morphology of delta ferrite was often seen on the fracture surfaces at the end of CGR tests. The fracture toughness J-R curve tests showed that both thermal aging and neutron irradiation can induce significant embrittlement. The loss of fracture toughness due to neutron irradiation was more pronounced in the unaged than aged specimens. After neutron irradiation, the fracture toughness values of the unaged and aged specimens were reduced to a similar level. G-phase precipitates were observed in the aged and irradiated specimens with or without prior aging. The similar microstructural changes resulting from thermal aging and irradiation suggest a common microstructural mechanism of inducing embrittlement in CF-8.

  7. Chronic acarbose treatment alleviates age-related behavioral and biochemical changes in SAMP8 mice.

    PubMed

    Tong, Jing-Jing; Chen, Gui-Hai; Wang, Fang; Li, Xue-Wei; Cao, Lei; Sui, Xu; Tao, Fei; Yan, Wen-Wen; Wei, Zhao-Jun

    2015-05-01

    The administration of maintaining the homeostasis of insulin/insulin-like growth factor 1 (IGF-1) signaling and/or glucose metabolism may reverse brain aging. In the present study, we investigated the effect of acarbose, an inhibitor of α-glucosidase, on age-related behavioral and biochemical changes. The SAMP8 mice were randomly divided into old control group and acarbose-treatment group. The mice in the acarbose group were administered acarbose (20 mg/kg/d, dissolved in drinking water) orally from 3 to 9 months of age when a new group of 3-month-old mice was added as young controls. The results showed that the aged controls exhibited declines in sensorimotor ability, open field anxiety, spatial and non-spatial memory abilities, decreased serum insulin levels, increased IGF-1 receptor and synaptotagmin 1 (Syt1) levels and decreased insulin receptor, brain-derived neurotrophic factor (BDNF) and syntaxin 1 (Stx1) levels in the hippocampal layers. The age-related behavioral deficits correlated with the serological and histochemical data. Chronic acarbose treatment relieved these age-related changes, especially with respect to learning and memory abilities. This protective effect of acarbose on age-related behavioral impairments might be related to changes in the insulin system and the levels of BDNF, IGF-1R, and the pre-synaptic proteins Syt1 and Stx1. In conclusion, long-term treatment with acarbose ameliorated the behavioral deficits and biochemical changes in old SAMP8 mice and promoted successful aging. This study provides insight into the potential of acarbose for the treatment of brain aging.

  8. Estradiol reduces anxiety- and depression-like behavior of aged female mice

    PubMed Central

    Walf, Alicia A.; Frye, Cheryl A.

    2013-01-01

    Beneficial effects of the ovarian steroid, 17β-estradiol (E2), for affective behavior have been reported in young individuals, but less is known about the effects of E2 among older individuals, and the capacity of older individuals to respond to E2 following its decline. In the present study, the effects of acute E2 administration to aged mice for anxiety-like and depression-like behaviors were investigated. Intact female C57BL/6 mice (N=18) that were approximately 24 months old were administered vehicle (sesame oil, n=9) or E2 (10 μg, n=9) subcutaneously 1h prior to behavioral testing. Mice were tested for anxiety-like behavior (open field, elevated plus maze, mirror chamber, light–dark transition task, Vogel conflict task) and depression-like behavior (forced swim task). To assess the role of general motor behavior and coordination in these aged mice, performance in an activity monitor and rotarod task, and total entries made in tasks (open field, elevated plus maze, light–dark transition task) were determined. Mice administered E2, compared to vehicle, demonstrated anti-anxiety behavior in the open field, mirror chamber, and light–dark transition task, and anti-depressive-like behavior in the forced swim task. E2 also tended to have anti-anxiety effects in the elevated plus maze and Vogel task compared to vehicle administration, but these effects did not reach statistical significance. E2 did not alter motor behavior and/or coordination in the activity monitor, open field, or rotarod tasks. Thus, an acute E2 regimen produced specific anti-anxiety and anti-depressant effects, independent of effects on motor behavior, when administered to aged female C57BL/6 mice. PMID:19804793

  9. The effects of genotype, age, and social environment on male ornamentation, mating behavior, and attractiveness.

    PubMed

    Miller, Lisa K; Brooks, Robert

    2005-11-01

    The traits thought to advertise genetic quality are often highly susceptible to environmental variation and prone to change with age. These factors may either undermine or reinforce the potential for advertisement traits to signal quality depending on the magnitude of age-dependent expression, environmental variation, and genotype-age and genotype-environment interaction. Measurements of the magnitude of these effects are thus a necessary step toward assessing the implications of age dependence and environmental variability for the evolution of signals of quality. We conducted a longitudinal study of male guppies (Poecilia reticulata) from 22 full-sibling families. Each fish was assigned at maturity to one of three treatments in order to manipulate his allocation of resources to reproduction: a control in which the male was kept alone, a courtship-only treatment in which he could see and court a female across a clear partition, and a mating treatment in which he interacted freely with a female. We measured each male's size, ornamental color patterns, courtship, attractiveness to females, and mating success at three ages. Size was influenced by treatment and age-treatment interactions, indicating that courtship and mating may impose costs on growth. Tail size and color patterns were influenced by age but not by treatment, suggesting fixed age-dependent trajectories in these advertisement traits. By contrast, display rate and attempted sneak copulation rate differed among treatments but not among ages, suggesting greater plasticity of these behavioral traits. As a result of the different patterns of variation in ornamentation and behavior, male attractiveness and mating success responded to male age, treatment, and the interaction between age and treatment. Neither age nor treatment obscured the presence of genetic variation, and the genetic relationship between male ornamentation and attractiveness remained the same among treatments. Our findings suggest that

  10. Model Identification and FE Simulations: Effect of Different Yield Loci and Hardening Laws in Sheet Forming

    SciTech Connect

    Flores, P.; Lelotte, T.; Bouffioux, C.; El Houdaigui, F.; Habraken, A.M.; Duchene, L.; Bael, A. van; He, S.; Duflou, J.

    2005-08-05

    The bi-axial experimental equipment developed by Flores enables to perform Baushinger shear tests and successive or simultaneous simple shear tests and plane-strain tests. Such experiments and classical tensile tests investigate the material behavior in order to identify the yield locus and the hardening models. With tests performed on two steel grades, the methods applied to identify classical yield surfaces such as Hill or Hosford ones as well as isotropic Swift type hardening or kinematic Armstrong-Frederick hardening models are explained. Comparison with the Taylor-Bishop-Hill yield locus is also provided. The effect of both yield locus and hardening model choice will be presented for two applications: Single Point Incremental Forming (SPIF) and a cup deep drawing.

  11. Model Identification and FE Simulations: Effect of Different Yield Loci and Hardening Laws in Sheet Forming

    NASA Astrophysics Data System (ADS)

    Flores, P.; Duchêne, L.; Lelotte, T.; Bouffioux, C.; El Houdaigui, F.; Van Bael, A.; He, S.; Duflou, J.; Habraken, A. M.

    2005-08-01

    The bi-axial experimental equipment developed by Flores enables to perform Baushinger shear tests and successive or simultaneous simple shear tests and plane-strain tests. Such experiments and classical tensile tests investigate the material behavior in order to identify the yield locus and the hardening models. With tests performed on two steel grades, the methods applied to identify classical yield surfaces such as Hill or Hosford ones as well as isotropic Swift type hardening or kinematic Armstrong-Frederick hardening models are explained. Comparison with the Taylor-Bishop-Hill yield locus is also provided. The effect of both yield locus and hardening model choice will be presented for two applications: Single Point Incremental Forming (SPIF) and a cup deep drawing.

  12. Deformation and strain hardening of different steels in impact dominated systems

    SciTech Connect

    Rojacz, H.; Mozdzen, G.; Winkelmann, H.

    2014-04-01

    Strain hardening is a common technique to exploit the full potential of materials in diverse applications. Single impact studies were performed to evaluate work hardening effects of different steels, correlated to their deformation at different energy and momentum levels. Three different steels were examined regarding their forming behavior and their tendency to strain harden in impact loading conditions, revealing different intensities of hardness increase, deformation and coinciding microstructural changes. Detailed studies in the deformed zone such as micro hardness mappings were performed to reveal the materials hardness increase in the deformed zones. Additionally high resolution scanning electron microscopy (HRSEM) supported by electron backscatter diffraction (EBSD) was used to determine microstructural changes. Results indicate, that the influence of different velocities/strain rates at constant energy levels cannot be neglected for the strain hardening behavior of steels and provide data for a better control of the hardness increase in impact dominated materials fabrication operations. - Highlights: • Deformation and strain hardening behaviour of three different steels. • Influence of impact energies and momenta on the strain hardening. • Hardness increase and depth controllable by momentum and energy.

  13. Cognition, behavior and social competence of preterm low birth weight children at school age

    PubMed Central

    Fan, Rachel Gick; Portuguez, Mirna Wetters; Nunes, Magda Lahorgue

    2013-01-01

    OBJECTIVE: The aim of this study was to assess the cognitive and behavioral development of preterm and low birth weight newborns living in a disadvantageous socioeconomic environment at school age. METHODS: This cross-sectional study included children aged 6-7 from a historical birth cohort of preterm (gestational age <37 weeks) and low birth weight (<2,500 g) infants. The Wechsler Intelligence Scale for Children III (WISC-III) was administered by a psychologist while the parents completed the Child Behavior Checklist. The results were compared to the test's reference. The perinatal information and follow-up data were collected from the hospital files. The demographic data were collected from the parents. The current performance was compared with the results from the Denver II and Bayley II tests, which were administered during the first years of life. RESULTS: The total intelligence quotient varied from 70 to 140 (mean 98.7±15.8). The borderline intelligence quotient was observed in 9.3% of the children. The Child Behavior Checklist indicated a predominance of social competence problems (27.8%, CI 19.2 to 37.9) compared with behavioral problems (15.5%, CI 8.9 to 24.2). Both the Child Behavior Checklist domains, such as schooling, social and attention problems, and the cognitive scores were significantly associated with maternal education and family income. The results of the Denver and Bayley tests were associated with the cognitive performance (p<0.001) and the Child Behavior Checklist social profile, including aggressive and externalizing behavior (p<0.001). CONCLUSIONS: Our data suggest that even low-risk preterm newborns are at risk for developing disturbances in early school age, such as mild cognitive deficits and behavioral disorders. This risk might increase under unfavorable socioeconomic conditions. PMID:23917653

  14. West Virginia Adolescents' Health Risk Behaviors: Differences by Gender, Age, Grade Level, and Level of Rurality.

    ERIC Educational Resources Information Center

    Meehan, Merrill L.; And Others

    In 1990, the Youth Risk Behavior Survey (YRBS) was completed by a random sample of 1,448 West Virginia public-school students in grades 9-12. The sample was 51 percent male and 89 percent white. About 71 percent of subjects were aged 15-17; 39 percent were in the ninth grade. The YRBS covered behaviors producing vehicle-related or other injuries,…

  15. Age- and Gender-Based Patterns in Youth All-Terrain Vehicle (ATV) Riding Behaviors.

    PubMed

    Jinnah, Hamida; Stoneman, Zolinda

    2016-01-01

    Injuries to youth on all-terrain vehicles (ATVs) have been increasing exponentially in recent years. Youth under age 16 years are 4 times more likely to require emergency room treatments. This study explored the relationships and differences in ATV risk and safety behaviors based on age, gender, and age at ATV driving/riding initiation. Data were collected from 180 farm youth between 10 and 19 years of age. The study brought to light an important factor that influences risky ATV behaviors of youth, namely, their age at ATV driving and riding initiation. The sooner that youth (boys and girls) were exposed to ATVs, including riding with their family or friends, the sooner they started driving ATVs themselves, and the more likely they were to indulge in several ATV risk behaviors when older. This effect was more pronounced for boys than girls. Overall, girls in this study were equally likely to engage in many of the risky ATV behaviors, such as taking and giving rides on single-seat ATVs, driving adult-sized ATVs, driving ATVs on public roads, and driving ATVs really fast. However, they were less likely to wear protective attire, leaving them more vulnerable to injuries and fatalities during crashes. Implications of the findings and future directions are discussed.

  16. Health Promotion Behaviors and Chronic Diseases of Aging in the Elderly People of Iranshahr*- IR Iran

    PubMed Central

    Mofrad, Zahra Pishkar; Jahantigh, Mozhgan; Arbabisarjou, Azizollah

    2016-01-01

    Introduction and Aim: Aging is considered as the phenomenon of the day in the health arena of the world and Iran. It is anticipated that there will be an explosion of aging population in Iran in about 2031 and 20-25% of the population will be aged over 60 years. With aging, chronic diseases also increase and diminish the functional ability of older people. On the other hand, increased healthcare costs should be also added to this issue. Health promotion is a concept of process that continues throughout life. As much as health promotion is important in children and adults, it is equally important in older people. In fact, the elderlies, as a group, also acquire many benefits from health promotion behaviors. Due to the increasing elderly population, geriatric health promotion and enhancing the health level of older people is proposed as a health priority that should be properly planned. Hence, the present study has been conducted in this regard and aims to identify behaviors of health promotion and chronic diseases of aging in the elderly people of Iranshahr-Iran. Materials and Methods: The present research is a cross-sectional descriptive study whose population consists of 425 elderly people aged 60 years and over, who lived in the city of Iranshahr*, IR Iran. The random cluster sampling method has been used to select the research samples. The required information was collected using a questionnaire which was distributed among the older people through visiting their homes; then, the collected data was statistically analyzed using the statistical software of SPSS version 13. Findings: The research findings show that the mean age of older people is 66.33 ± 7.7 and the highest frequency belongs to the age group of 60 years and the maximum age is 92 years. 69.5% of the older people were in the age group of the young elderly (60-69 years) and 44% of them lived with their married children; also 55.8%, 81.9%, 70.5%, and 74.4% of them were respectively female, illiterate

  17. Comprehensively Assessing Cognitive and Behavioral Risks for HIV Infection among Middle-Aged and Older Adults

    ERIC Educational Resources Information Center

    Paniagua, Freddy A.; O'Boyle, Michael

    2008-01-01

    A comprehensive survey of HIV/AIDS with middle-aged and older adults should include six domains (e.g., factual knowledge regarding the acquisition and transmission of HIV, traditionally-accepted behavioral risks for HIV infection). A sample of 23 women (54.8%) and 19 men (45.2%), ranging in age from 51 to 85 were surveyed across such domains.…

  18. Effects of brain-derived neurotrophic factor on dopaminergic function and motor behavior during aging.

    PubMed

    Boger, H A; Mannangatti, P; Samuvel, D J; Saylor, A J; Bender, T S; McGinty, J F; Fortress, A M; Zaman, V; Huang, P; Middaugh, L D; Randall, P K; Jayanthi, L D; Rohrer, B; Helke, K L; Granholm, A-C; Ramamoorthy, S

    2011-03-01

    Brain-derived neurotrophic factor (BDNF) is critical in synaptic plasticity and in the survival and function of midbrain dopamine neurons. In this study, we assessed the effects of a partial genetic deletion of BDNF on motor function and dopamine (DA) neurotransmitter measures by comparing Bdnf(+/-) with wildtype mice (WT) at different ages. Bdnf(+/-) and WT mice had similar body weights until 12 months of age; however, at 21 months, Bdnf(+/-) mice were significantly heavier than WT mice. Horizontal and vertical motor activity was reduced for Bdnf(+/-) compared to WT mice, but was not influenced by age. Performance on an accelerating rotarod declined with age for both genotypes and was exacerbated for Bdnf(+/-) mice. Body weight did not correlate with any of the three behavioral measures studied. Dopamine neurotransmitter markers indicated no genotypic difference in striatal tyrosine hydroxylase, DA transporter (DAT) or vesicular monoamine transporter 2 (VMAT2) immunoreactivity at any age. However, DA transport via DAT (starting at 12 months) and VMAT2 (starting at 3 months) as well as KCl-stimulated DA release were reduced in Bdnf(+/-) mice and declined with age suggesting an increasingly important role for BDNF in the release and uptake of DA with the aging process. These findings suggest that a BDNF expression deficit becomes more critical to dopaminergic dynamics and related behavioral activities with increasing age.

  19. Extracting material response from simple mechanical tests on hardening-softening-hardening viscoplastic solids

    NASA Astrophysics Data System (ADS)

    Mohan, Nisha

    Uniaxial Compression of Vertically Aligned Carbon Nanotubes," J. Mech.Phys. Solids, 59, pp. 2227--2237, Erratum 60, 1753-1756 (2012)], the property space exploration was advanced to three types of simple mechanical tests: 1) uniaxial compression, 2) uniaxial tension, and 3) nanoindentation with a conical and a flat-punch tip. The simulations attempt to explain some of the salient features in experimental data, like 1) The initial linear elastic response. 2) One or more nonlinear instabilities, yielding, and hardening. The model-inherent relationships between the material properties and the overall stress-strain behavior were validated against the available experimental data. The material properties include the gradient in stiffness along the height, plastic and elastic compressibility, and hardening. Each of these tests was evaluated in terms of their efficiency in extracting material properties. The uniaxial simulation results proved to be a combination of structural and material influences. Out of all deformation paths, flat-punch indentation proved to be superior since it is the most sensitive in capturing the material properties.

  20. Cyclic hardening mechanisms in Nimonic 80A

    NASA Technical Reports Server (NTRS)

    Lerch, B. A.; Gerold, V.

    1987-01-01

    A nickel base superalloy was fatigued under constant plastic strain range control. The hardening response was investigated as a function of plastic strain range and particle size of the gamma prime phase. Hardening was found to be a function of the slip band spacing. Numerous measurements of the slip band spacing and other statistical data on the slip band structures were obtained. Interactions between intersecting slip systems were shown to influence hardening. A Petch-Hall model was found to describe best this relationship between the response stress and the slip band spacing.

  1. Impact of Inuit customary adoption on behavioral problems in school-age Inuit children.

    PubMed

    Decaluwe, Béatrice; Jacobson, Sandra W; Poirier, Marie-Andrée; Forget-Dubois, Nadine; Jacobson, Joseph L; Muckle, Gina

    2015-05-01

    A large proportion of Inuit children in Arctic Quebec are adopted in accordance with traditional Inuit customs. In contrast to adoptions in Southern Canada and the United States, the child is adopted at birth and by a close family member; he or she knows who his or her biological parents are, and will typically have contact with them. Studies of other populations have reported an increased incidence of behavior problems in adopted compared with nonadopted children. This study examined the actual extent of the increase in the number of behavior problems seen in Inuit children adopted in accordance with traditional customs. In a prospective longitudinal study conducted in the Canadian Arctic (n = 46 adopted and 231 nonadopted children), prenatal and familial variables were documented at birth and at school age (M = 11.3 years). Behavior problems were assessed on the Teacher Report Form of the Child Behavior Checklist. Adopted children lived in more economically disadvantaged families, but their caregivers were less prone to depression, domestic violence, or alcohol abuse compared with those of the nonadopted children. The adoption status was not related to the teacher's report of attention problems, externalizing or internalizing behaviors, after controlling for confounders. Despite less favorable socioeconomic circumstances, a higher extent of behavioral problems was not seen at school age in Inuit children adopted at birth by a family member. Psychosocial stressors associated with adoption are more likely to be responsible for an association with higher levels of childhood behavior problems rather than adoption per se.

  2. Impact of Inuit customary adoption on behavioral problems in school-age Inuit children.

    PubMed

    Decaluwe, Béatrice; Jacobson, Sandra W; Poirier, Marie-Andrée; Forget-Dubois, Nadine; Jacobson, Joseph L; Muckle, Gina

    2015-05-01

    A large proportion of Inuit children in Arctic Quebec are adopted in accordance with traditional Inuit customs. In contrast to adoptions in Southern Canada and the United States, the child is adopted at birth and by a close family member; he or she knows who his or her biological parents are, and will typically have contact with them. Studies of other populations have reported an increased incidence of behavior problems in adopted compared with nonadopted children. This study examined the actual extent of the increase in the number of behavior problems seen in Inuit children adopted in accordance with traditional customs. In a prospective longitudinal study conducted in the Canadian Arctic (n = 46 adopted and 231 nonadopted children), prenatal and familial variables were documented at birth and at school age (M = 11.3 years). Behavior problems were assessed on the Teacher Report Form of the Child Behavior Checklist. Adopted children lived in more economically disadvantaged families, but their caregivers were less prone to depression, domestic violence, or alcohol abuse compared with those of the nonadopted children. The adoption status was not related to the teacher's report of attention problems, externalizing or internalizing behaviors, after controlling for confounders. Despite less favorable socioeconomic circumstances, a higher extent of behavioral problems was not seen at school age in Inuit children adopted at birth by a family member. Psychosocial stressors associated with adoption are more likely to be responsible for an association with higher levels of childhood behavior problems rather than adoption per se. PMID:25985112

  3. Impulse control and underlying functions of the left DLPFC mediate age-related and age-independent individual differences in strategic social behavior.

    PubMed

    Steinbeis, Nikolaus; Bernhardt, Boris C; Singer, Tania

    2012-03-01

    Human social exchange is often characterized by conflicts of interest requiring strategic behavior for their resolution. To investigate the development of the cognitive and neural mechanisms underlying strategic behavior, we studied children's decisions while they played two types of economic exchange games with differing demands of strategic behavior. We show an increase of strategic behavior with age, which could not be explained by age-related changes in social preferences but instead by developmental differences in impulsivity and associated brain functions of the left dorsolateral prefrontal cortex (DLPFC). Furthermore, observed differences in cortical thickness of lDLPFC were predictive of differences in impulsivity and strategic behavior irrespective of age. We conclude that egoistic behavior in younger children is not caused by a lack of understanding right or wrong, but by the inability to implement behavioral control when tempted to act selfishly; a function relying on brain regions maturing only late in ontogeny.

  4. Age-related behaviors have distinct transcriptional profiles in Caenorhabditis elegans.

    PubMed

    Golden, Tamara R; Hubbard, Alan; Dando, Caroline; Herren, Michael A; Melov, Simon

    2008-12-01

    There has been a great deal of interest in identifying potential biomarkers of aging. Biomarkers of aging would be useful to predict potential vulnerabilities in an individual that may arise well before they are chronologically expected, due to idiosyncratic aging rates that occur between individuals. Prior attempts to identify biomarkers of aging have often relied on the comparisons of long-lived animals to a wild-type control. However, the effect of interventions in model systems that prolong lifespan (such as single gene mutations or caloric restriction) can sometimes be difficult to interpret due to the manipulation itself having multiple unforeseen consequences on physiology, unrelated to aging itself. The search for predictive biomarkers of aging therefore is problematic, and the identification of metrics that can be used to predict either physiological or chronological age would be of great value. One methodology that has been used to identify biomarkers for numerous pathologies is gene expression profiling. Here, we report whole-genome expression profiles of individual wild-type Caenorhabditis elegans covering the entire wild-type nematode lifespan. Individual nematodes were scored for either age-related behavioral phenotypes, or survival, and then subsequently associated with their respective gene expression profiles. This facilitated the identification of transcriptional profiles that were highly associated with either physiological or chronological age. Overall, our approach serves as a paradigm for identifying potential biomarkers of aging in higher organisms that can be repeatedly sampled throughout their lifespan.

  5. Degradation of mechanical behavior in UHMWPE after natural and accelerated aging.

    PubMed

    Edidin, A A; Jewett, C W; Kalinowski, A; Kwarteng, K; Kurtz, S M

    2000-07-01

    Ultra-high molecular weight polyethylene (UHMWPE) is known to degrade during natural (shelf) aging following gamma irradiation in air, but the mechanical signature of degradation remains poorly understood. Accelerated aging methods have been developed to reproduce the natural aging process as well as to precondition total joint replacement components prior to joint simulator wear testing. In this study, we compared the mechanical behavior of naturally (shelf) aged and accelerated aged tibial inserts using a previously validated miniature specimen testing technique known as the small punch test. Tibial inserts made-of GUR 1120 and sterilized with 25 to 40 kGy of gamma radiation (in air) in 1988, 1993, and 1997 were obtained; a subset of the 1997 implants were subjected to 4 weeks of accelerated aging in air at 80 degrees C. To determine the spatial variation of mechanical properties within each insert, miniature disk shaped specimens were machined from the surface and subsurface regions of the inserts. Analysis of variance of the test data showed that aging significantly affected the small punch test measures of elastic modulus, initial load, ultimate load, ultimate displacement, and work to failure. The accelerated aging protocol was unable to reproduce the spatial mechanical profile seen in shelf aged components, but it did mechanically degrade the surface of GUR 1120 tibial components to an extent comparable to that seen after 10 years of natural aging. Test specimens showed a fracture morphology consistent with the decreased ductility and toughness which was corroborated by the small punch test metrics of this study. Our data support the hypothesis that UHMWPE undergoes a spatially nonuniform change towards a less ductile (more brittle) mechanical behavior after gamma irradiation in air and shelf aging.

  6. Socioeconomic inequalities in health after age 50: Are health risk behaviors to blame?

    PubMed Central

    Shaw, Benjamin A.; McGeever, Kelly; Grubert, Elizabeth; Agahi, Neda; Fors, Stefan

    2013-01-01

    Recent studies indicate that socioeconomic inequalities in health extend into the elderly population, even within the most highly developed welfare states. One potential explanation for socioeconomic inequalities in health focuses on the role of health behaviors, but little is known about the degree to which health behaviors account for health inequalities among older adults, in particular. Using data from the Health and Retirement Study (N=19,245), this study examined the degree to which four behavioral risk factors – smoking, obesity, physical inactivity, and heavy drinking – are associated with socioeconomic position among adults aged 51 and older, and whether these behaviors mediate socioeconomic differences in mortality, and the onset of disability among those who were disability-free at baseline, over a 10-year period from 1998–2008. Results indicate that the odds of both smoking and physical inactivity are higher among persons with lower wealth, with similar stratification in obesity, but primarily among women. The odds of heavy drinking decrease at lower levels of wealth. Significant socioeconomic inequalities in mortality and disability onset are apparent among older men and women; however, the role that health behaviors play in accounting for these inequalities differs by age and gender. For example, these health behaviors account for between 23–45% of the mortality disparities among men and middle aged women, but only about 5% of the disparities found among women over 65 years. Meanwhile, these health behaviors appear to account for about 33% of the disparities in disability onset found among women survivors, and about 9–14% among men survivors. These findings suggest that within the U.S. elderly population, behavioral risks such as smoking and physical inactivity contribute moderately to maintaining socioeconomic inequalities in health. As such, promoting healthier lifestyles among the socioeconomically disadvantaged older adults should help

  7. Characterization of Aging Behavior in M250 Grade Maraging Steel Using Ultrasonic Measurements

    NASA Astrophysics Data System (ADS)

    Rajkumar, K. V.; Kumar, Anish; Jayakumar, T.; Raj, Baldev; Ray, K. K.

    2007-02-01

    Ultrasonic measurements have been carried out in M250 grade maraging steel specimens subjected to solution annealing at 1093 K for 1 hour followed by aging at 755 K for various durations in the range of 0.25 to 100 hours. The influence of aging on microstructure, room temperature hardness, and ultrasonic parameters (longitudinal and shear wave velocities and Poisson’s ratio) has been studied in order to derive correlations among these parameters in aged M250 maraging steel. Both hardness and ultrasonic velocities exhibit almost similar behaviors with aging time. They increase with the precipitation of intermetallic phases, Ni3Ti and Fe2Mo, and decrease with the reversion of martensite to austenite. Ultrasonic shear wave velocity is found to be more influenced by the precipitation of intermetallic phases, whereas longitudinal wave velocity is influenced more by the reversion of martensite to austenite. Unlike hardness and ultrasonic velocities, the Poisson’s ratio exhibits a monotonous decrease with aging time and, hence, can be used for unambiguous monitoring of the aging process in M250 maraging steel. Further, none of the parameters, i.e., hardness, ultrasonic velocity, or Poisson’s ratio, alone could identify the initiation of the reversion of austenite at early stage; however, the same could be identified from the correlation between ultrasonic velocity and Poisson’s ratio, indicating the advantage of using the multiparametric approach for comprehensive characterization of complex aging behavior in M250 grade maraging steel.

  8. Exogenous Testosterone, Aging, and Changes in Behavioral Response of Gonadally Intact Male Mice

    PubMed Central

    Onaolapo, Olakunle J.; Onaolapo, Adejoke Y.; Omololu, Tope A.; Oludimu, Adedunke T.; Segun-Busari, Toluwalase; Omoleke, Taofeeq

    2016-01-01

    This study tested the hypothesis that aging significantly affects the influence of exogenous testosterone on neurobehavior in gonadally intact male mice. Groups of prepubertal and aged male mice received daily vehicle or testosterone propionate (TP; 2.5 or 5.0 mg/kg intraperitoneal [i.p.]) for 21 days. Behaviors were assessed on days 1 and 21. Weight gain was significant in prepubertal mice. Locomotion and rearing increased in prepubertal mice after first dose and decreased after last dose of TP. Rearing was suppressed in aged mice throughout. Suppression of grooming occurred in both age groups at day 21. Significant increase in working memory in both age groups was seen in the radial-arm maze (at specific doses) and in prepubertal mice in the Y-maze. Elevated plus maze test showed mixed anxiolytic/anxiogenic effects. Aged mice had higher serum testosterone. In conclusion, age is an important determinant for the influence of exogenous testosterone on behavior in gonadally intact male mice. PMID:27158222

  9. Effect of Aging Treatment on Fatigue Behavior of an Al-Cu-Mg-Ag Alloy

    NASA Astrophysics Data System (ADS)

    Burba, M. E.; Caton, M. J.; Jha, S. K.; Szczepanski, C. J.

    2013-11-01

    An investigation of the fatigue properties of an Al-Cu-Mg-Ag alloy with two different heat treatments—peak aged (T6), and peak aged interrupted (T6I4)—has been conducted. While the strength levels resulting from the two heat treatments were similar, the main difference between the microstructures was that the peak aged interrupted material contained a higher volume fraction of the θ' precipitates. This study specifically focused on the effects of these treatments on the fatigue lifetime distribution, and the role of crack initiation vs the small crack growth behavior. Several total fatigue lifetime tests were completed at room temperature and at a given stress level to characterize the distribution in fatigue lifetimes. Fatigue results indicate that there is almost no difference in the mean lifetime for either heat treatment, but there is a significant difference in the minimum lifetimes, where the peak aged condition exhibited a higher propensity for life-limiting failure mechanisms. The small crack growth behavior of the two aging treatments was studied both at room temperature and elevated temperature by means of a standard acetate replication method. The small crack growth rates at both temperatures were largely unaffected by the different aging treatments. Based on the given number of tests, results suggest that the life-limiting fatigue failures of the two aging treatments are primarily governed by different crack initiation mechanisms due to the differences seen in the density of θ' precipitates.

  10. Age-Related Differences in Judgments of Inappropriate Behavior are Related to Humor Style Preferences

    PubMed Central

    Stanley, Jennifer Tehan; Lohani, Monika; Isaacowitz, Derek M.

    2014-01-01

    Identifying social gaffes is important for maintaining relationships. Older adults are less able than young to discriminate between socially appropriate and inappropriate behavior in video clips. One open question is how these social appropriateness ratings relate to potential age differences in the perception of what is actually funny or not. In the present study, young, middle-aged, and older adults were equally able to discriminate between appropriate and inappropriate social behavior in a diverse set of clips relevant to both age groups. However, young and middle-aged adults rated the gaffe clips as funnier than control clips and young adults smiled more during the inappropriate clips than the control clips. Older adults did not show this pattern, suggesting that they did not find the inappropriate clips funny. Additionally, young adults endorsed a more aggressive humor style than middle-aged and older adults and aggressive humor style endorsement mediated age differences in social appropriateness ratings. Results are discussed in terms of possible mechanisms such as cohort differences in humor and developmental prioritization of certain humor styles, as well as the importance of investigating age differences in both abilities and preferences. PMID:25244473

  11. Age-related differences in judgments of inappropriate behavior are related to humor style preferences.

    PubMed

    Stanley, Jennifer Tehan; Lohani, Monika; Isaacowitz, Derek M

    2014-09-01

    Identifying social gaffes is important for maintaining relationships. Older adults are less able than young to discriminate between socially appropriate and inappropriate behavior in video clips. One open question is how these social appropriateness ratings relate to potential age differences in the perception of what is actually funny or not. In the present study, young, middle-aged, and older adults were equally able to discriminate between appropriate and inappropriate social behavior in a diverse set of clips relevant across age groups. However, young and middle-aged adults rated the gaffe clips as funnier than control clips and young adults smiled more during the inappropriate clips than the control clips. Older adults did not show this pattern, suggesting that they did not find the inappropriate clips funny. Additionally, young adults endorsed a more aggressive humor style than middle-aged and older adults and aggressive humor style endorsement mediated age differences in social appropriateness ratings. Results are discussed in terms of possible mechanisms such as cohort differences in humor and developmental prioritization of certain humor styles, as well as the importance of investigating age differences in both abilities and preferences. PMID:25244473

  12. Differences in cooperative behavior among Damaraland mole rats are consequences of an age-related polyethism.

    PubMed

    Zöttl, Markus; Vullioud, Philippe; Mendonça, Rute; Torrents Ticó, Miquel; Gaynor, David; Mitchell, Adam; Clutton-Brock, Tim

    2016-09-13

    In many cooperative breeders, the contributions of helpers to cooperative activities change with age, resulting in age-related polyethisms. In contrast, some studies of social mole rats (including naked mole rats, Heterocephalus glaber, and Damaraland mole rats, Fukomys damarensis) suggest that individual differences in cooperative behavior are the result of divergent developmental pathways, leading to discrete and permanent functional categories of helpers that resemble the caste systems found in eusocial insects. Here we show that, in Damaraland mole rats, individual contributions to cooperative behavior increase with age and are higher in fast-growing individuals. Individual contributions to different cooperative tasks are intercorrelated and repeatability of cooperative behavior is similar to that found in other cooperatively breeding vertebrates. Our data provide no evidence that nonreproductive individuals show divergent developmental pathways or specialize in particular tasks. Instead of representing a caste system, variation in the behavior of nonreproductive individuals in Damaraland mole rats closely resembles that found in other cooperatively breeding mammals and appears to be a consequence of age-related polyethism. PMID:27588902

  13. Maternal Age at Childbirth and Offspring Disruptive Behaviors: Testing the Causal Hypothesis

    ERIC Educational Resources Information Center

    D'Onofrio, Brian M.; Goodnight, Jackson A.; Van Hulle, Carol A.; Rodgers, Joseph Lee; Rathouz, Paul J.; Waldman, Irwin D.; Lahey, Benjamin B.

    2009-01-01

    Background: Recent studies suggest that the association between maternal age at childbearing (MAC) and children's disruptive behaviors is the result of family factors that are confounded with both variables, rather than a casual effect of environmental factors specifically related to MAC. These studies, however, relied on restricted samples and…

  14. Cognitive and Behavioral Indicators of ADHD Symptoms Prior to School Age

    ERIC Educational Resources Information Center

    Arnett, Anne Bernard; MacDonald, Beatriz; Pennington, Bruce F.

    2013-01-01

    Background: Previous research on the etiology of ADHD symptoms suggests that neuropsychological differences may be present as early as birth; however, the diagnosis is typically not given until school age. This study aimed to (a) identify early behavioral and cognitive markers of later significant parent and/or teacher ratings of ADHD…

  15. Delayed Adulthood, Delayed Desistance? Trends in the Age Distribution of Problem Behaviors

    ERIC Educational Resources Information Center

    Hayford, Sarah R.; Furstenberg, Frank F., Jr.

    2008-01-01

    As the transition to adulthood becomes more protracted and less orderly, fewer young people occupy adult roles and experience the social control associated with these roles. One might therefore expect behaviors associated with the teenage years to spill over into older age groups, reflecting postponed entrance into full social adulthood. We test…

  16. Neurocognitive and Behavioral Outcomes of Younger Siblings of Children with Autism Spectrum Disorder at Age Five

    ERIC Educational Resources Information Center

    Warren, Zachary E.; Foss-Feig, Jennifer H.; Malesa, Elizabeth E.; Lee, Evon Batey; Taylor, Julie Lounds; Newsom, Cassandra R.; Crittendon, Julie; Stone, Wendy L.

    2012-01-01

    Later-born siblings of children with Autism Spectrum Disorders (ASD) are at increased risk for ASD as well as qualitatively similar traits not meeting clinical cutoffs for the disorder. This study examined age five neurocognitive and behavioral outcomes of 39 younger siblings of children with ASD (Sibs-ASD) and 22 younger siblings of typically…

  17. Parental Loss and Eating-Related Cognitions and Behaviors in College-Age Women

    ERIC Educational Resources Information Center

    Beam, Minna R.; Servaty-Seib, Heather L.; Mathews, Laura

    2004-01-01

    To examine the eating-related cognitions and behaviors of college-age women who had experienced parental death, parental divorce, or neither loss condition, we recruited 48 women from science and social science departments at a state university in the Southeast. All participants completed the Mizes Anorectic Cognitions Scale (MAC) and the Bulimia…

  18. Dietary resistant starch improves selected brain and behavioral functions in adult and aged rodents

    PubMed Central

    Zhou, June; Keenan, Michael J.; Fernandez-Kim, Sun Ok; Pistell, Paul J.; Ingram, Donald K.; Li, Bing; Raggio, Anne M.; Shen, Li; Zhang, Hanjie; McCutcheon, Kathleen L; Tulley, Richard T.; Blackman, Marc R.; Keller, Jeffrey N.; Martin, Roy J.

    2013-01-01

    Resistant starch (RS) is a dietary fiber that exerts multiple beneficial effects. The current study explored the effects of dietary RS on selected brain and behavioral functions in adult and aged rodents. Because glucokinase (GK) expression in hypothalamic arcuate nucleus and area postrema of the brainstem is important for brain glucose sensing, GK mRNA was measured by brain nuclei microdissection and PCR. Adult RS-fed rats had a higher GK mRNA than controls in both brain nuclei, an indicator of improved brain glucose sensing. Next, we tested whether dietary RS improve selected behaviors in aged mice. RS-fed aged mice exhibited (1) an increased eating responses to fasting, a behavioral indicator of improvement in aged brain glucose sensing; (2) a longer latency to fall from an accelerating rotarod, a behavioral indicator of improved motor coordination; and (3) a higher serum active GLP-1. Third, GLP-1 receptor null (GLP-1RKO) mice were used to test the role of GLP-1 in brain glucose sensing, and they exhibited impaired eating responses to fasting. We conclude that in rodents (1) dietary RS improves two important indicators of brain function: glucose sensing and motor coordination, and that (2) GLP-1 is important in the optimal feeding response to a fast. PMID:23818307

  19. Progress in Research on Aging in the Behavioral and Social Sciences.

    ERIC Educational Resources Information Center

    Birren, James E.

    1980-01-01

    Proposes a biobehavioral view of research on aging which suggests that behavior depends upon the limits set by genetic heritage, the modifications and reinforcements of physical and social environments, and the self-concept achieved through the integration of past life experiences. (Author/SS)

  20. Sex Differences in Persistence Behavior of Children Ages 11-13.

    ERIC Educational Resources Information Center

    Campbell, Stephen N.; Henry, Rolando

    The relationship of boys' and girls' level of aspiration (LOA), achievement motivation, manifest anxiety, and intelligence to persistence behavior was explored in this study. Forty boys and 40 girls (ages 11-13) from two Catholic schools participated in this study. To measure subjects' persistence and LOA, subjects were given 5 sets of puzzle…

  1. Differences in cooperative behavior among Damaraland mole rats are consequences of an age-related polyethism.

    PubMed

    Zöttl, Markus; Vullioud, Philippe; Mendonça, Rute; Torrents Ticó, Miquel; Gaynor, David; Mitchell, Adam; Clutton-Brock, Tim

    2016-09-13

    In many cooperative breeders, the contributions of helpers to cooperative activities change with age, resulting in age-related polyethisms. In contrast, some studies of social mole rats (including naked mole rats, Heterocephalus glaber, and Damaraland mole rats, Fukomys damarensis) suggest that individual differences in cooperative behavior are the result of divergent developmental pathways, leading to discrete and permanent functional categories of helpers that resemble the caste systems found in eusocial insects. Here we show that, in Damaraland mole rats, individual contributions to cooperative behavior increase with age and are higher in fast-growing individuals. Individual contributions to different cooperative tasks are intercorrelated and repeatability of cooperative behavior is similar to that found in other cooperatively breeding vertebrates. Our data provide no evidence that nonreproductive individuals show divergent developmental pathways or specialize in particular tasks. Instead of representing a caste system, variation in the behavior of nonreproductive individuals in Damaraland mole rats closely resembles that found in other cooperatively breeding mammals and appears to be a consequence of age-related polyethism.

  2. Dietary resistant starch improves selected brain and behavioral functions in adult and aged rodents.

    PubMed

    Zhou, June; Keenan, Michael J; Fernandez-Kim, Sun Ok; Pistell, Paul J; Ingram, Donald K; Li, Bing; Raggio, Anne M; Shen, Li; Zhang, Hanjie; McCutcheon, Kathleen L; Tulley, Richard T; Blackman, Marc R; Keller, Jeffrey N; Martin, Roy J

    2013-11-01

    Resistant starch (RS) is a dietary fiber that exerts multiple beneficial effects. The current study explored the effects of dietary RS on selected brain and behavioral functions in adult and aged rodents. Because glucokinase (GK) expression in hypothalamic arcuate nucleus and area postrema of the brainstem is important for brain glucose sensing, GK mRNA was measured by brain nuclei microdissection and PCR. Adult RS-fed rats had a higher GK mRNA than controls in both brain nuclei, an indicator of improved brain glucose sensing. Next, we tested whether dietary RS improve selected behaviors in aged mice. RS-fed aged mice exhibited (i) an increased eating responses to fasting, a behavioral indicator of improvement in aged brain glucose sensing; (ii) a longer latency to fall from an accelerating rotarod, a behavioral indicator of improved motor coordination; and (iii) a higher serum active glucagon-like peptide-1 (GLP-1). Then, GLP-1 receptor null (GLP-1RKO) mice were used to test the role of GLP-1 in brain glucose sensing, and they exhibited impaired eating responses to fasting. We conclude that in rodents (i) dietary RS improves two important indicators of brain function: glucose sensing and motor coordination, and (ii) GLP-1 is important in the optimal feeding response to a fast.

  3. Cognitive and Behavioral Indicators of ADHD Symptoms Prior to School Age

    PubMed Central

    Arnett, Anne Bernard; MacDonald, Beatriz; Pennington, Bruce F.

    2013-01-01

    Background Previous research on the etiology of ADHD symptoms suggests that neuropsychological differences may be present as early as birth; however, the diagnosis is typically not given until school age. The current study aimed to 1) identify early behavioral and cognitive markers of later significant parent and/or teacher ratings of ADHD symptomology, 2) examine sex differences in these predictors, and 3) describe the developmental trajectories of comorbid symptoms in school aged children. Methods 1,106 children and at least one parent enrolled in the NICHD Study of Early Child Care and Youth Development were followed from 1 month of age through 6th grade. Effect size calculations, discriminant function analysis, and growth curve analyses were conducted to address the three aims. Results Children with high- versus low-ADHD symptomology at 3rd grade could be distinguished using cognitive and behavioral measures as early as 15 months (females) and 24 months (males). Sensitivity and specificity were modest at 15, 24 and 26 months. Growth curves revealed significant differences between high- and low-ADHD groups in comorbid symptoms at Kindergarten, and significantly different slopes for externalizing, social skills and academic skills ratings across elementary school. There were few gender differences on cognitive and behavioral variables within the high-ADHD group. Conclusions Cognitive and behavioral markers of ADHD symptoms are present in children prior to entry into formal schooling, but current behavioral screeners are not developmentally sensitive to these differences in infancy and toddlerhood. PMID:23848372

  4. Radiation-hardened asphaltite composites

    SciTech Connect

    Persinen, A.A.; Trubyatchinskaya, V.N.; Tolmacheva, T.P.

    1981-07-20

    A method is proposed for the production of an asphaltite block material with good physical and mechanical properties. The composite contains epoxide resin, acrylic acid, and asphaltite and radiation or radiation - thermal hardening was used. ED-16 epoxide resin with 490 molecular weight and 17.6% epoxide groups or EBF-23 epoxide resin produced from water-soluble shale phenols with 750 to 800 molecular weight and 21 to 22% epoxide groups was used as the epoxide resin. Analysis of the IR spectra showed that a rapid reaction of acrylic acid with epoxide resin occurs upon the action of ionizing radiation. The mechanical testing showed that the uniform samples obtained had rather high strength and hardness; high heat resistance and low water absorption was noted. The composites are chemically resistant towards concentrated HCl, water, acetone, and benzene. The studies indicated cross-linking occurs as a consequence of the reaction of the epoxide ring with acrylic acid. Asphaltite adds by means of the short alkyl substituents and guinoid structures. 4 tables. (DP)

  5. Insulin-like growth factor-1 ameliorates age-related behavioral deficits.

    PubMed

    Markowska, A L; Mooney, M; Sonntag, W E

    1998-12-01

    Insulin-like growth factor-1 has been found to be involved in the regulation of several aspects of brain metabolism, neural transmission, neural growth and differentiation. Because decreased insulin-like growth factor-1 and/or its receptors are likely to contribute to age-related abnormalities in behavior, the strategy of replacing this protein is one potential therapeutic alternative. The present study was designed to assess whether cognitive deficits with ageing may be partially overcome by increasing the availability of insulin-like growth factor-1 in the brain. Fischer-344 x Brown Norway hybrid (F1) male rats of two ages (four-months-old and 32-months-old) were preoperatively trained in behavioral tasks and subsequently implanted with osmotic minipumps to infuse the insulin-like growth factor-1 (23.5 microg/pump) or a vehicle, i.c.v. Animals were retested at two weeks and four weeks after surgery. Insulin-like growth factor-1 improved working memory in the repeated acquisition task and in the object recognition task. An improvement was also observed in the place discrimination task, which assesses reference memory. Insulin-like growth factor-1 had no effect on sensorimotor skills nor exploration, but mildly reversed some age-related deficits in emotionality. These data indicate a potentially important role for insulin-like growth factor-1 in the reversal of age-related behavioral impairments in rodents.

  6. Age, gender, and interpersonal behavior development using the FIRO-BC.

    PubMed

    Burton, S A; Goggin, W C

    1985-04-01

    It has been argued that many human behaviors follow predictable developmental patterns, or stages. The FIRO-BC was given to 9- through 13-year-old children (n = 282) to test for a stage-like progression in interpersonal behavior development. The data presented here failed to evidence an age-related progression. However, gender differences did appear in 11-year-olds and increased dramatically by age 13. Geographical differences were found in that the present data differed significantly from the normative data presented in the FIRO manual. The data also support the notion that, at least within the southern population tested. interpersonal behavior may be more related to puberty than has been previously supposed.

  7. Association of Eating Behavior With Nutritional Status and Body Composition in Primary School-Aged Children.

    PubMed

    Tay, Chee Wee; Chin, Yit Siew; Lee, Shoo Thien; Khouw, Ilse; Poh, Bee Koon

    2016-07-01

    Problematic eating behaviors during childhood may lead to positive energy balance and obesity. Therefore, this study aims to investigate the association of eating behaviors with nutritional status and body composition in Malaysian children aged 7 to 12 years. A total of 1782 primary schoolchildren were randomly recruited from 6 regions in Malaysia. The multidimensional Children's Eating Behaviour Questionnaire (CEBQ) was reported by parents to determine the 8 different dimensions of eating styles among children. Body mass index (BMI), BMI-for-age Z-score, waist circumference, and body fat percentage were assessed. Linear regression analyses revealed that both food responsiveness and desire to drink subscales were positively associated with a child's body adiposity, whereas satiety responsiveness, slowness in eating, and emotional undereating subscales were negatively associated with adiposity (all P < .05). A multidimensional eating style approach based on the CEBQ is needed to promote healthy eating behaviors in order to prevent excessive weight gain and obesity problems among Malaysian children. PMID:27252248

  8. Association of Eating Behavior With Nutritional Status and Body Composition in Primary School-Aged Children.

    PubMed

    Tay, Chee Wee; Chin, Yit Siew; Lee, Shoo Thien; Khouw, Ilse; Poh, Bee Koon

    2016-07-01

    Problematic eating behaviors during childhood may lead to positive energy balance and obesity. Therefore, this study aims to investigate the association of eating behaviors with nutritional status and body composition in Malaysian children aged 7 to 12 years. A total of 1782 primary schoolchildren were randomly recruited from 6 regions in Malaysia. The multidimensional Children's Eating Behaviour Questionnaire (CEBQ) was reported by parents to determine the 8 different dimensions of eating styles among children. Body mass index (BMI), BMI-for-age Z-score, waist circumference, and body fat percentage were assessed. Linear regression analyses revealed that both food responsiveness and desire to drink subscales were positively associated with a child's body adiposity, whereas satiety responsiveness, slowness in eating, and emotional undereating subscales were negatively associated with adiposity (all P < .05). A multidimensional eating style approach based on the CEBQ is needed to promote healthy eating behaviors in order to prevent excessive weight gain and obesity problems among Malaysian children.

  9. Alloy solution hardening with solute pairs

    DOEpatents

    Mitchell, John W.

    1976-08-24

    Solution hardened alloys are formed by using at least two solutes which form associated solute pairs in the solvent metal lattice. Copper containing equal atomic percentages of aluminum and palladium is an example.

  10. Process for hardening the surface of polymers

    DOEpatents

    Mansur, L.K.; Lee, E.H.

    1992-07-14

    Hard surfaced polymers and the method for making them is generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface and improved wear resistance. 1 figure.

  11. Extraordinary strain hardening by gradient structure.

    PubMed

    Wu, XiaoLei; Jiang, Ping; Chen, Liu; Yuan, Fuping; Zhu, Yuntian T

    2014-05-20

    Gradient structures have evolved over millions of years through natural selection and optimization in many biological systems such as bones and plant stems, where the structures change gradually from the surface to interior. The advantage of gradient structures is their maximization of physical and mechanical performance while minimizing material cost. Here we report that the gradient structure in engineering materials such as metals renders a unique extra strain hardening, which leads to high ductility. The grain-size gradient under uniaxial tension induces a macroscopic strain gradient and converts the applied uniaxial stress to multiaxial stresses due to the evolution of incompatible deformation along the gradient depth. Thereby the accumulation and interaction of dislocations are promoted, resulting in an extra strain hardening and an obvious strain hardening rate up-turn. Such extraordinary strain hardening, which is inherent to gradient structures and does not exist in homogeneous materials, provides a hitherto unknown strategy to develop strong and ductile materials by architecting heterogeneous nanostructures.

  12. Process for hardening the surface of polymers

    DOEpatents

    Mansur, Louis K.; Lee, Eal H.

    1992-01-01

    Hard surfaced polymers and the method for making them is generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface and improved wear resistance.

  13. Fatigue hardening in niobium single crystals.

    NASA Technical Reports Server (NTRS)

    Doner, M.; Diprimio, J. C.; Salkovitz, E. I.

    1973-01-01

    Nb single crystals of various orientations were cyclically deformed in tension-compression under strain control. At low strain amplitudes all crystals oriented for single slip and some oriented for multiple slip showed a two stage hardening. When present, the first stage was characterized with almost no cyclic work hardening. The rate of hardening in the second stage increased with strain amplitude and the amount of secondary slip. In crystals oriented for single slip kink bands developed on their side faces during rapid hardening stage which resulted in considerable amount of asterism in Laue spots. A cyclic stress-strain curve independent of prior history was found to exist which was also independent of crystal orientation. Furthermore, this curve differed only slightly from that of polycrystalline Nb obtained from data in literature.

  14. Study on the limited hardenability steel

    SciTech Connect

    Xu, L.P.; Li, L.; Min, Y.A.; Xu, M.H.; Le, J.P.; Liu, R.H.

    1998-12-31

    A series of measurements were taken in the limited hardenability bearing steel rings which were induction hardened and tempered. Measurements showed several features which strengthened the rings: (1) Compressive residual stress are generated from surface to a depth of 3.2 mm and high residual compressive stress at the location where fatigue fracture initiates. (2) The matrix of the hardened layer was composed mainly of lath martensite with dispersed carbides whose formula was Me{sub 3} according to the X-ray spectrum analysis. The carbon content of martensite was estimated to be lower than 0.58% (by weight). The core was constituted of troostite transformed from spheroidal carbide. (3) The amount of retained austenite in the hardened layer was about 5% (in volume) which ensures the high dimensional stability of bearing.

  15. Innovative Structural Materials and Sections with Strain Hardening Cementitious Composites

    NASA Astrophysics Data System (ADS)

    Dey, Vikram

    The motivation of this work is based on development of new construction products with strain hardening cementitious composites (SHCC) geared towards sustainable residential applications. The proposed research has three main objectives: automation of existing manufacturing systems for SHCC laminates; multi-level characterization of mechanical properties of fiber, matrix, interface and composites phases using servo-hydraulic and digital image correlation techniques. Structural behavior of these systems were predicted using ductility based design procedures using classical laminate theory and structural mechanics. SHCC sections are made up of thin sections of matrix with Portland cement based binder and fine aggregates impregnating continuous one-dimensional fibers in individual or bundle form or two/three dimensional woven, bonded or knitted textiles. Traditional fiber reinforced concrete (FRC) use random dispersed chopped fibers in the matrix at a low volume fractions, typically 1-2% to avoid to avoid fiber agglomeration and balling. In conventional FRC, fracture localization occurs immediately after the first crack, resulting in only minor improvement in toughness and tensile strength. However in SHCC systems, distribution of cracking throughout the specimen is facilitated by the fiber bridging mechanism. Influence of material properties of yarn, composition, geometry and weave patterns of textile in the behavior of laminated SHCC skin composites were investigated. Contribution of the cementitious matrix in the early age and long-term performance of laminated composites was studied with supplementary cementitious materials such as fly ash, silica fume, and wollastonite. A closed form model with classical laminate theory and ply discount method, coupled with a damage evolution model was utilized to simulate the non-linear tensile response of these composite materials. A constitutive material model developed earlier in the group was utilized to characterize and

  16. Age of Partner at First Adolescent Intercourse and Adult Sexual Risk Behavior Among Women

    PubMed Central

    Carey, Michael P.

    2011-01-01

    Abstract Background Adolescent females who have early sexual experiences with older male partners report high rates of sexual risk behavior during adolescence, but little is known about whether these early sexual experiences are associated with adult sexual risk behavior. The purpose of this study was to investigate whether having first consensual sex with an older partner was associated with sexual risk behavior in adulthood. Methods Participants were 292 women (66% African American, mean age = 26 years) attending a public sexually transmitted disease (STD) clinic who reported having voluntary vaginal sex before age 18. Participants completed a computerized survey assessing child/adolescent sexual experiences and current adult sexual risk behavior. Results Participants were, on average, 14.6 years at first vaginal intercourse; their partners were, on average, 17.5 years. After controlling for covariates, a greater partner age difference at first intercourse was associated with more episodes of unprotected sex with a steady partner and a greater proportion of episodes of unprotected sex with a steady partner in the past 3 months. Conclusions Having an older first sex partner during adolescence was associated with sexual risk behavior in adulthood. Early sexual experiences may be important life events that influence subsequent sexual behavior. Sexual health interventions need to target female adolescents before they initiate sexual intercourse to reduce risk for STDs and human immunodeficiency virus (HIV) infection. PMID:21128817

  17. Effect of an organic additive on the rheology of an aluminous cement paste and consequences on the densification of the hardened material

    NASA Astrophysics Data System (ADS)

    El Hafiane, Y.; Smith, A.; Bonnet, J. P.; Tanouti, B.

    2005-03-01

    The material used in the present work is Secar 71 (Lafarge) mixed with water containing an organic additive (acetic acid noted HOAc). The rheological behavior of these pastes is studied. The best dispersion is obtained when the mass content of the additive with respect to the cement is equal to 0.5%. The microstructural characterizations of samples aged 4 days at 20° C and 95 % relative humidity reveal a significant increase in the density and a reduction in porosity for very small percentages of additive. The remarkable effect of the acetic acid on the microstructure of hardened material is correlated with its good dispersing action.

  18. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  19. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  20. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  1. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  2. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  3. [Beam hardening correction method for X-ray computed tomography based on subsection beam hardening curves].

    PubMed

    Huang, Kui-dong; Zhang, Ding-hua

    2009-09-01

    After researching the forming principle of X-ray beam hardening and analyzing the usual methods of beam hardening correction, a beam hardening correction model was established, in which the independent variable was the projection gray, and so the computing difficulties in beam hardening correction can be reduced. By considering the advantage and disadvantage of fitting beam hardening curve to polynomial, a new expression method of the subsection beam hardening curves based on polynomial was proposed. In the method, the beam hardening data were fitted firstly to a polynomial curve which traverses the coordinate origin, then whether the got polynomial curve surged in the fore-part or back-part of the fitting range was judged based on the polynomial curvature change. If the polynomial fitting curve surged, the power function curve was applied to replace the surging parts of the polynomial curve, and the C1 continuity was ensured at the joints of the segment curves. The experimental results of computed tomography (CT) simulation show that the method is well stable in the beam hardening correction for the ideal CT images and CT images with added noises, and can mostly remove the beam hardening artifact at the same time.

  4. Decline in Radiation Hardened Microcircuit Infrastructure

    NASA Technical Reports Server (NTRS)

    LaBel, Kenneth A.

    2015-01-01

    Two areas of radiation hardened microcircuit infrastructure will be discussed: 1) The availability and performance of radiation hardened microcircuits, and, and 2) The access to radiation test facilities primarily for proton single event effects (SEE) testing. Other areas not discussed, but are a concern include: The challenge for maintaining radiation effects tool access for assurance purposes, and, the access to radiation test facilities primarily for heavy ion single event effects (SEE) testing. Status and implications will be discussed for each area.

  5. Longitudinal Relations Between Observed Parenting Behaviors and Dietary Quality of Meals From Ages 2 to 5

    PubMed Central

    Montaño, Zorash; Smith, Justin D.; Dishion, Thomas J.; Shaw, Daniel S.; Wilson, Melvin N.

    2015-01-01

    Objectives Parents influence a child’s diet by modeling food choices, selecting the food they will make available, and controlling the child’s intake. Few studies have examined the covariation between parent’s behavior management practices and their guidance and support for a young child’s nutritional environment in early childhood. We hypothesized that parents’ positive behavior support (PBS), characterized as skillful behavior management and proactive structuring of children’s activities, would predict dietary quality over the course of early childhood (age 2 to 5 years), a critical period for the development of a dietary lifestyle through the lifespan. Methods Participants included 731 culturally diverse, low-income families in a randomized, controlled trial of the Family Check-Up. Families participated in a yearly home visit videotaped assessment when children were 2 to 5 years. PBS and dietary quality of meals parents served to their children were assessed by coding videotapes of structured parent–child interactions, including a meal preparation task. A cross-lagged panel model was used to evaluate the longitudinal relation between PBS and the dietary quality of meals served during the meal preparation task. Results Analyses revealed that PBS repeatedly predicted meals’ dietary quality the following year: age 2–3 (β = .30), age 3–4 (β = 0.14), age 4–5 (β = 0.37). Dietary quality significantly predicted PBS 1 year later: age 3–4 (β = 0.16), age 4–5 (β = 0.14). As expected, the relative strength of the relationship from PBS to dietary quality was significantly stronger than the reverse, from dietary quality to PBS. Conclusions Positive behavior management and proactive parenting practices are an important foundation for establishing a healthy nutritional environment for young children. These findings suggest that family-centered prevention interventions for pediatric obesity may benefit from targeting PBS in service of promoting

  6. Laser Surface Hardening of AISI 1045 Steel

    NASA Astrophysics Data System (ADS)

    Li, Ruifeng; Jin, Yajuan; Li, Zhuguo; Qi, Kai

    2014-09-01

    The study investigates laser surface hardening in the AISI 1045 steel using two different types of industrial laser: a high-power diode laser (HPDL) and a CO2 laser, respectively. The effect of process parameters such as beam power, travel speed on structure, case depth, and microhardness was examined. In most cases, a heat-affected zone (HAZ) formed below the surface; a substantial increase in surface hardness was achieved. In addition, big differences were found between the hardened specimens after HPDL surface hardening and CO2 laser surface hardening. For HPDL, depths of the HAZ were almost equal in total HAZ o, without surface melting. For CO2 laser, the depths changed a lot in the HAZ, with surface melting in the center. To better understand the difference of laser hardening results when use these two types of laser, numerical (ANSYS) analysis of the heat conduction involved in the process was also studied. For HPDL method, a rectangular beam spot and uniform energy distribution across the spot were assumed, while for CO2 laser, a circular beam spot and Gaussian energy distribution were assumed. The results showed that the energy distribution variety altered the thermal cycles of the HAZ dramatically. The rectangular HPDL laser beam spot with uniform energy distribution is much more feasible for laser surface hardening.

  7. Study on the Influence of the Work Hardening Models Constitutive Parameters Identification in the Springback Prediction

    NASA Astrophysics Data System (ADS)

    Oliveira, M. C.; Alves, J. L.; Chaparro, B. M.; Menezes, L. F.

    2005-08-01

    The main goal of this work is to determine the influence of the work hardening model in the numerical prediction of springback. This study will be performed according with the specifications of the first phase of the "Benchmark 3" of the Numisheet'2005 Conference: the "Channel Draw". Several work hardening constitutive models are used in order to allow a better description of the different material mechanical behavior. Two are classical pure isotropic hardening models described by a power law (Swift) or a Voce type saturation equation. Those two models were also combined with a non-linear (Lemaître and Chaboche) kinematic hardening rule. The final one is the Teodosiu microstructural hardening model. The study is performed for two commonly used steels of the automotive industry: mild (DC06) and dual phase (DP600) steels. The mechanical characterization, as well as the constitutive parameters identification of each work hardening models, was performed by LPMTM, based on an appropriate set of experimental data such as uniaxial tensile tests, monotonic and Bauschinger simple shear tests and orthogonal strain path tests, all at various orientations with respect to the rolling direction. All the simulations were carried out with the CEMUC's home code DD3IMP (contraction of `Deep Drawing 3-D IMPlicit code').

  8. Extramarital sexual relationships of middle-aged Danish men: attitudes and behavior.

    PubMed

    Solstad, K; Mucic, D

    1999-05-31

    This study explored Danish men's attitudes and behavior towards extramarital sexual relations (ESR), seen from two sides: men who had engaged in such relations (involved) and men who had not (non-involved). The participants, 439 men aged 51, completed a questionnaire concerning sexuality (behavior, attitudes and experience) as a part of a Danish cohort-investigation of health risk-factors. Thereafter 100 of the 439 men were interviewed. A high degree of permissiveness toward ESR emerged in both involved and non-involved individuals but approval of ESR was higher among the participants who were involved in ESR. The frequency of ESR increased with higher social rank. Both involved and non-involved participants mostly did not consider the ESR as a serious threat to the marital happiness. Attitudes-behavior discrepancies are discussed seen in the light of the social norms and known attitudes-behavior models.

  9. Assessment of cheating behavior in young school-age children: distinguishing normative behaviors from risk markers of externalizing psychopathology.

    PubMed

    Callender, Kevin A; Olson, Sheryl L; Kerr, David C R; Sameroff, Arnold J

    2010-01-01

    The central goal of this longitudinal study was to develop a laboratory-based index of children's covert cheating behavior that distinguished normative rule violations from those that signal risk for antisocial behavior. Participants (N = 215 children) were drawn from a community population and oversampled for externalizing behavior problems (EXT). Cheating behavior was measured using two resistance-to-temptation tasks and coded for extent of cheating, latency to cheat, and inappropriate positive affect. Mothers rated internalized conduct and three forms of self-regulation: inhibitory control, impulsivity, and affective distress. Mothers and teachers reported EXT concurrently (T1) and 4 years later, when children averaged 10 years of age (T2). Children categorized as severe cheaters manifested lower inhibitory control, greater impulsivity, and lower levels of internalized conduct at T1. Children in this group also manifested higher levels of EXT in home and school settings at T1 and more EXT in the school setting at T2, even after accounting for T1 ratings. PMID:21058125

  10. Assessment of cheating behavior in young school-age children: distinguishing normative behaviors from risk markers of externalizing psychopathology.

    PubMed

    Callender, Kevin A; Olson, Sheryl L; Kerr, David C R; Sameroff, Arnold J

    2010-01-01

    The central goal of this longitudinal study was to develop a laboratory-based index of children's covert cheating behavior that distinguished normative rule violations from those that signal risk for antisocial behavior. Participants (N = 215 children) were drawn from a community population and oversampled for externalizing behavior problems (EXT). Cheating behavior was measured using two resistance-to-temptation tasks and coded for extent of cheating, latency to cheat, and inappropriate positive affect. Mothers rated internalized conduct and three forms of self-regulation: inhibitory control, impulsivity, and affective distress. Mothers and teachers reported EXT concurrently (T1) and 4 years later, when children averaged 10 years of age (T2). Children categorized as severe cheaters manifested lower inhibitory control, greater impulsivity, and lower levels of internalized conduct at T1. Children in this group also manifested higher levels of EXT in home and school settings at T1 and more EXT in the school setting at T2, even after accounting for T1 ratings.

  11. Effect of Aging on the Fracture Behavior of Lean Duplex Stainless Steels

    NASA Astrophysics Data System (ADS)

    Straffelini, G.; Baldo, S.; Calliari, I.; Ramous, E.

    2009-11-01

    The influence of aging in the range of 550 °C to 850 °C for 5 to 120 minutes on the impact fracture behavior of 2101 and 2304 lean duplex stainless steels (DSS) was investigated in the present study. The 2304 steel displayed ductile behavior irrespective of aging conditions. In contrast, the 2101 steel displayed a ductile behavior only in the case of aging for 5 minutes at 550 °C and 650 °C, whereas in all other cases, it fractured in a brittle manner. The brittle fracture behavior of the 2101 steel has been attributed to the precipitation of small black particles at the α/ α and α/ γ grain boundaries (nitrides), which form paths for easy crack propagation. In the 2304 steel, such particles precipitated at 750 °C and 850 °C, but they were located inside the austenitic grains because of the formation of secondary austenite. They therefore did not embrittle the steel. The larger Ni content of the 2304 steel favored the formation of the secondary austenite that is absent in the 2101 steel.

  12. Aging and loading rate effects on the mechanical behavior of equine bone

    NASA Astrophysics Data System (ADS)

    Kulin, Robb M.; Jiang, Fengchun; Vecchio, Kenneth S.

    2008-06-01

    Whether due to a sporting accident, high-speed impact, fall, or other catastrophic event, the majority of clinical bone fractures occur under dynamic loading conditions. However, although extensive research has been performed on the quasi-static fracture and mechanical behavior of bone to date, few high-quality studies on the fracture behavior of bone at high strain rates have been performed. Therefore, many questions remain regarding the material behavior, including not only the loading-rate-dependent response of bone, but also how this response varies with age. In this study, tests were performed on equine femoral bone taken post-mortem from donors 6 months to 28 years of age. Quasi-static and dynamic tests were performed to determine the fracture toughness and compressive mechanical behavior as a function of age at varying loading rates. Fracture paths were then analyzed using scanning confocal and scanning-electron microscopy techniques to assess the role of various microstructural features on toughening mechanisms.

  13. Facilitators and Inhibitors of Health-promoting Behaviors: The Experience of Iranian Women of Reproductive Age

    PubMed Central

    Baheiraei, Azam; Mirghafourvand, Mojgan; Charandabi, Sakineh Mohammad-Alizadeh; Mohammadi, Eesa

    2013-01-01

    Background: There is scant information on the facilitators and inhibitors of health-promoting behaviors among reproductive-aged Iranian women. This study aims to explore the experience of factors influencing health-promoting behaviors among Iranian women of reproductive age from a qualitative perspective. Methods: This study was performed in Tehran in 2011, over about 8 months. Qualitative methods, specifically in-depth interviews, were used to gather data on 15 women of reproductive age. Data continued to be collected until introduction of new information ceased. The interviews were recorded, transcribed verbatim, and analyzed by conventional content analysis. Results: The reported factors were categorized into four main groups and 12 subgroups: (1) personal barriers (lack of time, school or work duties, lack of preparation or motivation, physical disability); (2) socio-environmental barriers (family responsibilities, environmental pressures, high-costs and financial pressures); (3) personal facilitators (personal interest and motivation, experience of disease); and (4) socio-environmental facilitators (family and social support networks, encouraging and motivating environment, media, and public education). Conclusions: In these women's experience, factors influencing health-promoting behaviors were either facilitators or inhibitors; most were inhibitors. The findings of this study show that, in addition to personal factors, the pursuit of health-promoting behaviors is affected by socio-environmental factors. These results will be useful in designing interventions and plans for women's health promotion that focus on the improvement of their environment and the modification of social factors. PMID:24049620

  14. Age-dependent relevance of endogenous 5-lipoxygenase derivatives in anxiety-like behavior in mice.

    PubMed

    Leo, Luciana M; Almeida-Corrêa, Suellen; Canetti, Claudio A; Amaral, Olavo B; Bozza, Fernando A; Pamplona, Fabricio A

    2014-01-01

    When 5-lipoxygenase (5-LO) is inhibited, roughly half of the CNS effect of the prototypic endocannabinoid anandamide (AEA) is lost. Therefore, we decided to investigate whether inhibiting this enzyme would influence physiological functions classically described as being under control of the endocannabinoid system. Although 5-LO inhibition by MK-886 reduced lipoxin A4 levels in the brain, no effect was found in the elevated plus maze (EPM), even at the highest possible doses, via i.p. (10 mg/kg,) or i.c.v. (500 pmol/2 µl) routes. Accordingly, no alterations in anxiety-like behavior in the EPM test were observed in 5-LO KO mice. Interestingly, aged mice, which show reduced circulating lipoxin A4 levels, were sensitive to MK-886, displaying an anxiogenic-like state in response to treatment. Moreover, exogenous lipoxin A4 induced an anxiolytic-like profile in the EPM test. Our findings are in line with other reports showing no difference between FLAP KO or 5-LO KO and their control strains in adult mice, but increased anxiety-like behavior in aged mice. We also show for the first time that lipoxin A4 affects mouse behavior. In conclusion, we propose an age-dependent relevancy of endogenous 5-LO derivatives in the modulation of anxiety-like behavior, in addition to a potential for exogenous lipoxin A4 in producing an anxiolytic-like state.

  15. Effect of aging and deformation on the microstructure and properties of Fe-Ni-Ti maraging steel

    NASA Astrophysics Data System (ADS)

    Shekhter, A.; Aaronson, H. I.; Miller, M. K.; Ringer, S. P.; Pereloma, E. V.

    2004-03-01

    The age-hardening behavior of Fe-25.3Ni-1.7 Ti (wt pct) alloy both in undeformed specimens and in specimens cold deformed by 10 or 20 pct prior to aging was studied. The microstructural changes during aging were observed using transmission electron microscopy (TEM) and atom probe analysis and there were related to the mechanical properties as measured by microhardness and shear punch testing. An excellent combination of hardness, strength, and ductility was achieved after only 5 seconds aging at 550°C. We propose that this rapid strengthening is due to a dislocation friction effect arising from the formation of a fine dispersion of Ni-Ti atomic co-clusters during this short aging time. The concomitant effects of a reverse transformation of martensite to austenite during aging and a gradual increase in both size of the clusters and distance between them contributed to a decrease in strength after aging for 15 seconds. This decline proceeded until aging for 300 seconds and was followed by a secondary hardening reaction toward peak hardness (at 10,800 seconds) and subsequent overaging. This secondary hardening was associated with fine-scale precipitation of Ni3Ti and this process was accelerated by deformation prior to aging, leading to a reduction or elimination of hardness decline after the initial cluster hardening.

  16. School-age adopted Chinese girls' behavioral adjustment, academic performance, and social skills: longitudinal results.

    PubMed

    Tan, Tony Xing

    2009-04-01

    Longitudinal data on 177 school-age adopted Chinese girls (Time 1: mean age = 8.92 years, SD = 1.76; Time 2: mean age = 11.18 years, SD = 1.79) were analyzed to determine their long-term outcomes in behavioral adjustment, academic performance (measured with the Child Behavior Checklist/6-18), and social skills (measured with the Social Skills Rating System) and how these outcomes were related to preadoption adversity. More than 90% of the girls were adopted at 24 months or younger (M = 19.25, SD = 21.67). Results revealed that over a 2-year period, there was a moderate to strong stability in the children's behavioral adjustment and academic performance. However, there was a significant increase in the number of children with deviant internalizing problems. At both times, higher degrees of preadoption adversity were related to more internalizing problems and poorer academic performance. Children who were adopted at older ages had poorer academic performance. Children who were older had a lower level of assertion and a higher level of responsibility. Children's attention problems at Time 1 mediated the effect of preadoption adversity on academic performance at Time 2.

  17. Age and Individual Foraging Behavior Predict Tooth Wear in Amboseli Baboons

    PubMed Central

    Galbany, Jordi; Altmann, Jeanne; Pérez-Pérez, Alejandro; Alberts, Susan C.

    2010-01-01

    Teeth represent an essential component of the foraging apparatus for any mammal, and tooth wear can have significant implications for survival and reproduction. This study focuses on tooth wear in wild baboons in Amboseli, southern Kenya. We obtained mandibular and maxillary tooth impressions from 95 baboons and analyzed digital images of replicas made from these impressions. We measured tooth wear as the percent dentine exposure (PDE, the percent of the occlusal surface on which dentine was exposed), and we examined the relationship of PDE to age, behavior, and life history variables. We found that PDE increased significantly with age for both sexes in all three molar types. In females, we also tested the hypotheses that long-term patterns of feeding behavior, social dominance rank, and one measure of maternal investment (the cumulative number of months that a female had dependent infants during her lifetime) would predict tooth wear when we controlled for age. The hypothesis that feeding behavior predicted tooth wear was supported. The percent of feeding time spent consuming grass corms predicted PDE when controlling for age. However, PDE was not associated with social dominance rank or maternal investment. Am J Phys Anthropol 000:000–000, 2010. PMID:20721946

  18. Synergistic Effects of Physical Aging and Damage on Long-Term Behavior of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Brinson, L. Cate

    1999-01-01

    The research consisted of two major parts, first modeling and simulation of the combined effects of aging and damage on polymer composites and secondly an experimental phase examining composite response at elevated temperatures, again activating both aging and damage. For the simulation, a damage model for polymeric composite laminates operating at elevated temperatures was developed. Viscoelastic behavior of the material is accounted for via the correspondence principle and a variational approach is adopted to compute the temporal stresses within the laminate. Also, the effect of physical aging on ply level stress and on overall laminate behavior is included. An important feature of the model is that damage evolution predictions for viscoelastic laminates can be made. This allows us to track the mechanical response of the laminate up to large load levels though within the confines of linear viscoelastic constitutive behavior. An experimental investigation of microcracking and physical aging effects in polymer matrix composites was also pursued. The goal of the study was to assess the impact of aging on damage accumulation, in ten-ns of microcracking, and the impact of damage on aging and viscoelastic behavior. The testing was performed both at room and elevated temperatures on [+/- 45/903](sub s) and [02/903](sub s) laminates, both containing a set of 90 deg plies centrally located to facilitate investigation of microcracking. Edge replication and X-ray-radiography were utilized to quantify damage. Sequenced creep tests were performed to characterize viscoelastic and aging parameters. Results indicate that while the aging times studied have limited ]Influence on damage evolution, elevated temperature and viscoelastic effects have a profound effect on the damage mode seen. Some results are counterintuitive, including the lower strain to failure for elevated temperature tests and the catastrophic failure mode observed for the [+/- 45/9O3](sub s), specimens. The

  19. Directionality Between Tolerance of Deviance and Deviant Behavior is Age-Moderated in Chronically Stressed Youth.

    PubMed

    Ridenour, Ty A; Caldwell, Linda L; Coatsworth, J Douglas; Gold, Melanie A

    2011-03-20

    Problem behavior theory posits that tolerance of deviance is an antecedent to antisocial behavior and substance use. In contrast, cognitive dissonance theory implies that acceptability of a behavior may increase after experiencing the behavior. Using structural equation modeling, this investigation tested whether changes in tolerance of deviance precede changes in conduct disorder criteria or substance use or vice versa, or if they change concomitantly. Two-year longitudinal data from 246 8- to 16-year-olds suggested that tolerance of deviance increases after conduct disorder criteria or substance use in 8-to-10- and 11-to-12-year-olds. These results were consistent with cognitive dissonance theory. In 13-to-16- year-olds, no directionality was suggested, consistent with neither theory. These results were replicated in boys and girls and for different types of conduct disorder criteria aggression (covert behavior), deceitfulness and vandalism (overt behavior), and serious rule-breaking (authority conflict). The age-specific directionality between tolerance of deviance and conduct disorder criteria or substance use is consistent with unique etiologies between early onset versus adolescent-onset subtypes of behavior problems.

  20. Directionality Between Tolerance of Deviance and Deviant Behavior is Age-Moderated in Chronically Stressed Youth

    PubMed Central

    Ridenour, TY A.; Caldwell, Linda L.; Coatsworth, J. Douglas; Gold, Melanie A.

    2011-01-01

    Problem behavior theory posits that tolerance of deviance is an antecedent to antisocial behavior and substance use. In contrast, cognitive dissonance theory implies that acceptability of a behavior may increase after experiencing the behavior. Using structural equation modeling, this investigation tested whether changes in tolerance of deviance precede changes in conduct disorder criteria or substance use or vice versa, or if they change concomitantly. Two-year longitudinal data from 246 8- to 16-year-olds suggested that tolerance of deviance increases after conduct disorder criteria or substance use in 8-to-10- and 11-to-12-year-olds. These results were consistent with cognitive dissonance theory. In 13-to-16- year-olds, no directionality was suggested, consistent with neither theory. These results were replicated in boys and girls and for different types of conduct disorder criteria aggression (covert behavior), deceitfulness and vandalism (overt behavior), and serious rule-breaking (authority conflict). The age-specific directionality between tolerance of deviance and conduct disorder criteria or substance use is consistent with unique etiologies between early onset versus adolescent-onset subtypes of behavior problems. PMID:22180721

  1. Study on the Aging Behaviors of Rubber Materials in Tension and Compression Loads

    NASA Astrophysics Data System (ADS)

    Jiang, Can; Wang, Hongyu; Ma, Xiaobing

    Rubber materials are widely used in aviation, aerospace, shipbuilding, automobile and other military field. However, rubber materials are easy to aging, which largely restricts its using life. In working environment, due to the combined effect of heat and oxygen, vulcanized rubber will undergo degradation and crosslinking reaction which will cause elasticity decease and permanent deformation, so mostly rubber products are used under stress state. Due to the asymmetric structure and asymmetric stress distribution, mechanical stress may cause serious damage to molecular structure; therefore, this paper is aimed to analyze the aging behavior of rubber materials under tensile and compressive loadings, through analyzing experiment data, and adopting Gauss function to describe stress relaxation coefficient, to build an aging equation containing compression ratio parameter and aging time.

  2. Age modulates the effect of COMT genotype on delay discounting behavior

    PubMed Central

    Smith, Christopher T.; Boettiger, Charlotte A.

    2012-01-01

    Rationale and objective A form of impulsivity, the tendency to choose immediate over delayed rewards (delay-discounting) has been associated with a single nucleotide polymorphism (SNP) in the catechol-O-methyltransferase (COMT) gene (COMTval158met; rs4680). However, existing data regarding the nature of this association conflicts. We have previously reported that adults homozygous for valine (val) at the COMTval158met SNP demonstrate greater delay-discounting than do methionine (met) allele carriers (Boettiger et al. 2007). In contrast, a recent study of adolescent males found that those with the met/met genotype demonstrate greater delay-discounting than do val-allele carriers (Paloyelis et al. 2010). Based on reported age-related changes in frontal dopamine function and COMT expression, we hypothesized that the association of COMT genotype with delay-discounting behavior is modulated by age from late adolescence to young adulthood. Methods To test this hypothesis, we genotyped late adolescents (18–21 years; n=72) and adults (22–40 years; n=70) for the COMTval158met polymorphism, measured their delay-discounting behavior, and tested for an interaction between age group and COMT genotype. Results This cross-sectional study found that age modulates COMTval158met genotype effects on delay-discounting behavior. Among met-carriers, delay-discounting was negatively correlated with age from late adolescence to adulthood, while among val/val individuals delay-discounting was positively correlated with age across this range. Conclusions These results confirm our previous finding of enhanced delay-discounting among val/val adults relative to met-allele carriers, and help reconcile existing literature. We propose a single U-shaped model of the relationship between frontal DA levels and impulsive choice that accounts for both adolescent and adult data. PMID:22349272

  3. The effects of age and lifetime flight behavior on flight capacity in Drosophila melanogaster.

    PubMed

    Lane, Steven J; Frankino, W Anthony; Elekonich, Michelle M; Roberts, Stephen P

    2014-05-01

    The effects of flight behavior on physiology and senescence may be profound in insects because of the extremely high metabolic costs of flight. Flight capacity in insects decreases with age; in contrast, limiting flight behavior extends lifespan and slows the age-related loss of antioxidant capacity and accumulation of oxidative damage in flight muscles. In this study, we tested the effects of age and lifetime flight behavior on flight capacity by measuring wingbeat frequency, the ability to fly in a hypo-dense gas mixture, and metabolic rate in Drosophila melanogaster. Specifically, 5-day-old adult flies were separated into three life-long treatments: (1) those not allowed to fly (no flight), (2) those allowed - but not forced - to fly (voluntary flight) and (3) those mechanically stimulated to fly (induced flight). Flight capacity senesced earliest in flies from the no-flight treatment, followed by the induced-flight group and then the voluntary flight group. Wingbeat frequency senesced with age in all treatment groups, but was most apparent in the voluntary- and induced-flight groups. Metabolic rate during agitated flight senesced earliest and most rapidly in the induced flight group, and was low and uniform throughout age in the no-flight group. Early senescence in the induced-flight group was likely due to the acceleration of deleterious aging phenomena such as the rapid accumulation of damage at the cellular level, while the early loss of flight capacity and low metabolic rates in the no-flight group demonstrate that disuse effects can also significantly alter senescence patterns of whole-insect performance.

  4. Stepwise work hardening induced by individual grain boundary in Cu bicrystal micropillars.

    PubMed

    Li, L L; Zhang, Z J; Tan, J; Jiang, C B; Qu, R T; Zhang, P; Yang, J B; Zhang, Z F

    2015-10-22

    Vast experiments have demonstrated that the external specimen size makes a large difference in the deformation behavior of crystalline materials. However, as one important kind of internal planar defects, the role of grain boundary (GB) in small scales needs to be clarified in light of the scarce and inconsistent experimental results at present. Through compression of Cu bicrystal and its counterpart monocrystal micropillars, it is found that, in contrast to the monocrystals, the bicrystals are characterized by work hardening with discrete strain bursts. Interestingly, the stress rise between two adjacent strain bursts of the bicrystals increases with the decrease of specimen size. The results suggest that GBs play a critical role in the work hardening of materials in small scales, which may provide important implications to further understand the general work hardening behaviors of materials in the future.

  5. Cyclic hardening in copper described in terms of combined monotonic and cyclic stress-strain curves

    SciTech Connect

    Chandler, H.D. . School of Mechanical Engineering)

    1995-01-01

    Hardening of polycrystalline copper subjected to tension-compression loading cycles in the plastic region is discussed with reference to changes in flow stress determined from equations describing dislocation glide. It is suggested that hardening is as a result of the accumulation of strain on a monotonic stress-strain curve. On initial loading, the behavior is monotonic. On stress reversal, a characteristic cyclic stress-strain curve is followed until the stress reaches a value in reverse loading corresponding to the maximum attained during the preceding half cycle. Thereafter, the monotonic path is followed until strain reversal occurs at completion of the half cycle. Repetition of the process results in cyclic hardening. Steady state cyclic behavior is reached when a stress associated with the monotonic stress-strain curve is reached which is equal to the stress associated with the cyclic stress-strain curve corresponding to the imposed strain amplitude.

  6. Point defect concentrations and solid solution hardening in NiAl with Fe additions

    SciTech Connect

    Pike, L.M.; Chang, Y.A.; Liu, C.T.

    1997-08-01

    The solid solution hardening behavior exhibited when Fe is added to NiAl is investigated. This is an interesting problem to consider since the ternary Fe additions may choose to occupy either the Ni or the Al sublattice, affecting the hardness at differing rates. Moreover, the addition of Fe may affect the concentrations of other point defects such as vacancies and Ni anti-sites. As a result, unusual effects ranging from rapid hardening to solid solution softening are observed. Alloys with varying amounts of Fe were prepared in Ni-rich (40 at. % Al) and stoichiometric (50 at. % Al) compositions. Vacancy concentrations were measured using lattice parameter and density measurements. The site occupancy of Fe was determined using ALCHEMI. Using these two techniques the site occupancies of all species could be uniquely determined. Significant differences in the defect concentrations as well as the hardening behavior were encountered between the Ni-rich and stoichiometric regimes.

  7. Interaction Between Age and Exposure to 56Fe Particles on Behavior and Neurochemistry

    NASA Astrophysics Data System (ADS)

    Shukitt-Hale, B.; Carey, A. N.; Rabin, B. M.; Joseph, J. A.

    Previous research has shown that exposure to HZE particles and protons which will be encountered on long-term space missions can adversely affect the ability of rats to perform a variety of behavioral tasks This outcome has implications for an astronaut s ability to successfully complete requirements associated with these missions It has also been found that irradiation can lead to increases in oxidative stress similar to that seen in the aging brain Given that astronauts are often middle-aged or older it is important to determine if their age puts them at higher risk for the potentially hazardous effects of exposure to HZE particles Therefore we exposed young and old rats to either 1 or 2Gy of 56 Fe irradiation and evaluated performance in a spatial learning and memory task in addition to examining levels of dopamine DA release from superfused striatal slices Results indicated that exposure to 56 Fe particles can produce alterations in behavior and signaling and that these alterations may be more apparent in older organisms which suggests that the aging brain may be more susceptible to the deleterious effects of irradiation on performance Therefore age may be a factor for consideration in planning long-term missions into space Supported by NASA Grants NAG9-1190 and NAG9-1529

  8. Interaction between age and exposure to 56Fe particles on behavior and neurochemistry

    NASA Astrophysics Data System (ADS)

    Carey, Amanda N.; Shukitt-Hale, Barbara; Rabin, Bernard M.; Joseph, James A.

    Previous research has shown that exposure to HZE particles, which will be encountered on long-term space missions, can adversely affect the ability of rats to perform a variety of behavioral tasks. This outcome has implications for an astronaut’s ability to successfully complete requirements associated with these missions. It has also been found that irradiation can lead to increases in oxidative stress, similar to that seen in the aging brain. Given that astronauts are often middle-aged or older it is important to determine if their age puts them at higher risk for the potentially hazardous effects of exposure to HZE particles. Therefore, we exposed young and old rats to either 1 or 2 Gy of 56Fe irradiation and evaluated performance in a spatial learning and memory task, in addition to examining levels of dopamine (DA) release from superfused striatal slices. Results indicated that exposure to 56Fe particles can produce alterations in behavior and neuronal signaling and that these alterations may be more apparent in older organisms, a finding which suggests that the aging brain may be more susceptible to the deleterious effects of irradiation on performance. Therefore, age may be a factor for consideration in planning long-term missions into space.

  9. Determination of Constant Parameters of Copper as Power-Law Hardening Material at Different Test Conditions

    NASA Astrophysics Data System (ADS)

    Kowser, Md. A.; Mahiuddin, Md.

    2014-11-01

    In this paper a technique has been developed to determine constant parameters of copper as a power-law hardening material by tensile test approach. A work-hardening process is used to describe the increase of the stress level necessary to continue plastic deformation. A computer program is used to show the variation of the stress-strain relation for different values of stress hardening exponent, n and power-law hardening constant, α . Due to its close tolerances, excellent corrosion resistance and high material strength, in this analysis copper (Cu) has been selected as the material. As a power-law hardening material, Cu has been used to compute stress hardening exponent, n and power-law hardening constant, α from tensile test experiment without heat treatment and after heat treatment. A wealth of information about mechanical behavior of a material can be determined by conducting a simple tensile test in which a cylindrical specimen of a uniform cross-section is pulled until it ruptures or fractures into separate pieces. The original cross sectional area and gauge length are measured prior to conducting the test and the applied load and gauge deformation are continuously measured throughout the test. Based on the initial geometry of the sample, the engineering stress-strain behavior (stress-strain curve) can be easily generated from which numerous mechanical properties, such as the yield strength and elastic modulus, can be determined. A universal testing machine is utilized to apply the load in a continuously increasing (ramp) manner according to ASTM specifications. Finally, theoretical results are compared with these obtained from experiments where the nature of curves is found similar to each other. It is observed that there is a significant change of the value of n obtained with and without heat treatment it means the value of n should be determined for the heat treated condition of copper material for their applications in engineering fields.

  10. Study on the behavior and mechanism of polycarbonate with hot-water aging

    NASA Astrophysics Data System (ADS)

    Kong, L. P.; Zhao, Y. X.; Zhou, C. H.; Huang, Y. H.; Tang, M.; Gao, J. G.

    2016-07-01

    The present work was concerned with hot-water aging behavior and mechanism of Bisphenol A polycarbonate (PC) used as food and packaging materials. It indicated that with the aging time prolonged, PC sample had internal defects and the mechanical properties of PC materials changed not too much, molecular weight decreased, thermal stability declined. Phenolic hydroxyl absorption intensity enhanced in IR spectra and the maximum absorption wavelength red shift of benzene in UV-Vis spectra, the level of BPA increased. The color change of PC sample was not apparent.

  11. Impact of Inuit customary adoption on behavioral problems in school-age Inuit children

    PubMed Central

    Decaluwe, Béatrice; Jacobson, Sandra W.; Poirier, Marie-Andrée; Forget-Dubois, Nadine; Jacobson, Joseph L.; Muckle, Gina

    2015-01-01

    A large proportion of Inuit children in Arctic Quebec are adopted in accordance with traditional Inuit customs. In contrast to adoptions in Southern Canada and the USA, the child is adopted at birth and by a close family member; he/she knows who his/her biological parents are, and will typically have contact with them. Studies of other populations have reported an increased incidence of behavior problems in adopted compared with non-adopted children. Objectives This study examined the actual extent of the increase in the number of behavior problems seen in Inuit children adopted in accordance with traditional customs. Methods In a prospective longitudinal study conducted in the Canadian Arctic (n = 46 adopted and 231 non-adopted children), prenatal and familial variables were documented at birth and at school age (M = 11.3 years). Behavior problems were assessed on the Teacher Report Form of the Child Behavior Checklist. Results Adopted children lived in more economically disadvantaged families, but their caregivers were less prone to depression, domestic violence, or alcohol abuse compared with those of the non-adopted children. The adoption status was not related to the teacher’s report of attention problems, externalizing or internalizing behaviors, after controlling for confounders. Conclusion Despite less favorable socioeconomic circumstances, a higher extent of behavioral problems was not seen at school age in Inuit children adopted at birth by a family member. Psychosocial stressors associated with adoption are more likely to be responsible for an association with higher levels of childhood behavior problems rather than adoption per se. PMID:25985112

  12. School Entry Age and Children's Social-Behavioral Skills: Evidence From a National Longitudinal Study of U.S. Kindergartners

    ERIC Educational Resources Information Center

    Datar, Ashlesha; Gottfried, Michael A.

    2015-01-01

    Prior research evaluating school entry age effects has largely overlooked the effects on social-behavioral skills despite the growing recognition of returns to such skills. This study is the first to examine the effects of kindergarten entry age on children's social-behavioral outcomes using 9 years of panel data on a national sample of U.S.…

  13. HIV Risk Behavior of Runaway Youth in San Francisco: Age of Onset and Relation to Sexual Orientation.

    ERIC Educational Resources Information Center

    Moon, Martha W.; McFarland, William; Kellogg, Timothy; Baxter, Michael; Katz, Mitchell H.; MacKellar, Duncan; Valleroy, Linda A.

    2000-01-01

    Examined HIV risk behaviors among runaway youth by age at onset and sexual orientation. Adolescents age 12-21 years seeking health care at two clinics completed interviews and blood testing. Gay/lesbian/bisexual youth reported higher levels and earlier onset of sexual and drug-using behavior than heterosexual youth and were at exceptionally high…

  14. Age-related behaviors have distinct transcriptional profiles in C.elegans

    PubMed Central

    Golden, Tamara R.; Hubbard, Alan; Dando, Caroline; Herren, Michael A.; Melov, Simon

    2008-01-01

    Summary There has been a great deal of interest in identifying potential biomarkers of aging (Butler et al. 2004). Biomarkers of aging would be useful to predict potential vulnerabilities in an individual that may arise well before they are chronologically expected, due to idiosyncratic aging rates that occur between individuals. Prior attempts to identify biomarkers of aging have often relied on the comparisons of long-lived animals to a wild-type control (Dhahbi et al. 2004). However, the effect of interventions in model systems that prolong lifespan (such as single gene mutations, or caloric restriction) can sometimes be difficult to interpret due to the manipulation itself having multiple unforeseen consequences on physiology, unrelated to aging itself (Gems et al. 2002; Partridge & Gems 2006). The search for predictive biomarkers of aging therefore is problematic, and the identification of metrics that can be used to predict either physiological or chronological age would be of great value (Butler et al. 2004). One methodology which has been used to identify biomarkers for numerous pathologies is gene expression profiling. Here, we report whole-genome expression profiles of individual wild-type Caenorhabditis elegans covering the entire wild-type nematode life span. Individual nematodes were scored for either age-related behavioral phenotypes, or survival, and then subsequently associated with their respective gene expression profiles. This facilitated the identification of transcriptional profiles that were highly associated with either physiological or chronological age. Overall, our approach serves as a paradigm for identifying potential biomarkers of aging in higher organisms that can be repeatedly sampled throughout their lifespan. PMID:18778409

  15. Clarifying the Associations between Age at Menarche and Adolescent Emotional and Behavioral Problems

    PubMed Central

    Van Hulle, Carol A.; Beasley, William H.; Rodgers, Joseph L.; D’Onofrio, Brian M.

    2015-01-01

    Better understanding risk factors for the development of adolescent emotional and behavioral problems can help with intervention and prevention efforts. Previous studies have found that an early menarcheal age predicts several adolescent problems, including depressive symptoms, delinquency, and early age at first intercourse. Few studies, nevertheless, have explicitly tested (a) whether the associations with menarcheal age vary across racial/ethnic groups or (b) whether the sources of the associations are within-families (i.e., consistent with a direct, causal link) or only between-families (i.e., due to selection or confounding factors). The current study analyzed data from a nationally representative US Sample of females (N = 5,637). We examined whether race/ethnicity moderated the associations between early menarche and several adolescent problems by using multiple-group analyses and we examined the degree to which genetic and environmental factors shared by family members account for the associations by comparing sisters and cousins with differing menarcheal ages. Menarcheal age predicted subsequent depressive symptoms, delinquency, and early age at first intercourse in the population. The magnitudes of the associations were similar across all racial/ethnic groups for all outcomes. The within-family associations (i.e., when comparing siblings and cousins with different menarcheal age) were large and statistically significant when predicting early intercourse, but not the other outcomes. The findings suggest that selection or confounding factors account for the associations between menarcheal age and subsequent depressive symptoms and delinquency, whereas the independent association between menarcheal age and early age at first intercourse is consistent with a direct, causal effect. PMID:25687264

  16. Bullying behaviors among Chinese school-aged youth: a prevalence and correlates study in Guangdong Province.

    PubMed

    Wu, Jie; He, Yuan; Lu, Ciyong; Deng, Xueqing; Gao, Xue; Guo, Lan; Wu, Hong; Chan, Fanfan; Zhou, Ying

    2015-02-28

    Bullying among school-aged youth is a common issue worldwide and is increasingly being recognized as an important problem affecting both victims and perpetrators. Most of the bullying studies have been conducted in western countries, and their implications in other regions are limited due to different cultural contexts. The goal of our study is to identify the prevalence of bullying and its correlates school-aged youth in Guangdong province. In total, 1098 (7.1%) students reported having bullied other students, 744 (4.8%) students reported having been bullied by other students and 396 (2.6%) students reported having both bullied other students and been bullied by other students. There was a strong association between bullying others as well as being bullied and suicidal ideations, suicidal attempts, and self-harm behaviors. The prevalence of bullying and its associations with delinquent behaviors warrant the importance of school facility based preventive intervention taking into account both victims and perpetrators.

  17. Colony Defense Behavior of the Primitively Eusocial Wasp, Mischocyttarus cerberus is Related to Age

    PubMed Central

    Togni, Olga Coutinho; Giannotti, Edilberto

    2010-01-01

    The colony defense behavior of the wasp Mischocyttarus cerberus Richards (Hymenoptera, Vespidae) was studied to verify whether there were different reactions of wasps of different ages and hierarchical positions during attacks of ants. Detailed nest mapping was first performed, then the wasps were marked and were divided in four distinct categories: queens, older workers, younger workers and males. Tests were made simulating attacks of ants in the nests. The main results showed that the M. cerberus behaviors against ant attacks is more related to the age of the wasps than to their hierarchical position. The oldest wasps (queens and older workers) defend the nest more than the younger workers and males, representing a form of temporal polyethism. PMID:20883135

  18. Neural and behavioral bases of age differences in perceptions of trust

    PubMed Central

    Castle, Elizabeth; Eisenberger, Naomi I.; Seeman, Teresa E.; Moons, Wesley G.; Boggero, Ian A.; Grinblatt, Mark S.; Taylor, Shelley E.

    2012-01-01

    Older adults are disproportionately vulnerable to fraud, and federal agencies have speculated that excessive trust explains their greater vulnerability. Two studies, one behavioral and one using neuroimaging methodology, identified age differences in trust and their neural underpinnings. Older and younger adults rated faces high in trust cues similarly, but older adults perceived faces with cues to untrustworthiness to be significantly more trustworthy and approachable than younger adults. This age-related pattern was mirrored in neural activation to cues of trustworthiness. Whereas younger adults showed greater anterior insula activation to untrustworthy versus trustworthy faces, older adults showed muted activation of the anterior insula to untrustworthy faces. The insula has been shown to support interoceptive awareness that forms the basis of “gut feelings,” which represent expected risk and predict risk-avoidant behavior. Thus, a diminished “gut” response to cues of untrustworthiness may partially underlie older adults’ vulnerability to fraud. PMID:23213232

  19. Neural changes associated with semantic processing in healthy aging despite intact behavioral performance.

    PubMed

    Lacombe, Jacinthe; Jolicoeur, Pierre; Grimault, Stephan; Pineault, Jessica; Joubert, Sven

    2015-10-01

    Semantic memory recruits an extensive neural network including the left inferior prefrontal cortex (IPC) and the left temporoparietal region, which are involved in semantic control processes, as well as the anterior temporal lobe region (ATL) which is considered to be involved in processing semantic information at a central level. However, little is known about the underlying neuronal integrity of the semantic network in normal aging. Young and older healthy adults carried out a semantic judgment task while their cortical activity was recorded using magnetoencephalography (MEG). Despite equivalent behavioral performance, young adults activated the left IPC to a greater extent than older adults, while the latter group recruited the temporoparietal region bilaterally and the left ATL to a greater extent than younger adults. Results indicate that significant neuronal changes occur in normal aging, mainly in regions underlying semantic control processes, despite an apparent stability in performance at the behavioral level. PMID:26282079

  20. A statewide survey of age at first intercourse for adolescent females and age of their male partners: relation to other risk behaviors and statutory rape implications.

    PubMed

    Leitenberg, H; Saltzman, H

    2000-06-01

    In a statewide survey of a representative sample of adolescent girls in 8th-12th grades (N = 4201), information was obtained on age at first intercourse and age of their male partners. Excluding intercourse experiences where physical force was threatened or used, 31% had intercourse by age 15 and 45% by age 16. Contrary to the impression left by studies of teenage mothers, girls who first had sex between age 13 and age 15 or between age 16 and age 18 did not have a large percentage of much older partners (5 or more years older; 12 and 7%, respectively). The percentage of much older partners was higher, however, for girls who had sex in very early adolescence, ages 11-12 (34%). Much older male partners were associated with greater problem behaviors for girls who first had intercourse in very early adolescence (11-12), but less so for those who first had intercourse between age 13 and age 15 (truancy only) and not at all for those who first had intercourse at between 16 and 18. Regardless of partner's age disparity, earlier age at first intercourse during adolescence was associated with a greater number of other problem behaviors. The implications of these findings for recent calls to enforce statutory rape laws more stringently to reduce teenage pregnancy were discussed. PMID:10992978

  1. Incorporating the effect of orientation hardening in an effective temperature nonequilibrium theory for glassy polymers

    NASA Astrophysics Data System (ADS)

    Guo, Jingkai; Xiao, Rui; Nguyen, Thao

    Amorphous polymers exhibit a wide range of time and temperature dependent behavior. Recently, Xiao and Nguyen developed an effective temperature theory that can capture a wide variety of nonequilibrium behaviors at moderate strains. At large strains, the stress response of glassy polymers is dominated by strain hardening as a result of chain alignment. The goal of this study was to extend the effective temperature theory to large deformation and make it capable of modeling strain hardening from deformation-induced molecular alignment. We compared two approaches. In the spirit of internal state variable thermodynamics theory, we introduced a series of stretch-like internal state variables to characterize the molecular resistance to plastic flow associated with each inelastic mechanism. The dependence of free energy on the internal state variables naturally gives rise to a deformation dependent back stress. The flow rule and the evolution of effective temperatures were derived in a thermodynamically consistent manner. In the second approach, we introduced a steady-state limit in the evolution of the effective temperature characterizing the nonequilibrium structure of the material. Both approaches can well capture the experimentally measured phenomena of orientation hardening, including the development of deformation-induced anisotropy in the yield strength and hardening modulus, the Bauschinger effect, and differences in the hardening moduli in tension and compression of pre-oriented specimens.

  2. Beneficial behavioral, neurochemical and molecular effects of 1-(R)-aminoindan in aged mice.

    PubMed

    Badinter, Felix; Amit, Tamar; Bar-Am, Orit; Youdim, Moussa B H; Weinreb, Orly

    2015-12-01

    Previous neuroprotective studies demonstrated that 1-(R)-aminoindan (AI), which is the major metabolite of the anti-Parkinsonian drug rasagiline, possesses beneficial pharmacological effects in various cell culture and animal models of neurodegeneration. The present study was aimed at investigating the possible neuroprotective effects of AI on cognitive impairments and neurochemical alterations in aged mice. Our findings provide evidence that following chronic systemic treatment with AI (5 mg/kg; daily; 3 months) of aged mice (24 months old), the compound exerted a significant positive impact on neuropsychiatric functions and cognitive behavior deficits, assessed in a variety of tasks (spatial learning and memory retention, working memory, learning abilities and nest building behavior) and produced an antidepressant-like effect. In addition, chronic AI treatment significantly enhanced expression levels of neurotrophins, including brain derived neurotrophic factor (BDNF) and nerve growth factor (NGF), tyrosine kinase- B (Trk-B) receptor and synaptic plasticity markers, such as synapsin-1 and growth-associated protein-43 (GAP-43) in the striatum and hippocampus in aged mice. Our results also indicate that AI treatment up-regulated the expression levels of the pro-survival Bcl-2 mRNA, increased the anti-apoptotic index Bcl-2/Bax and enhanced the activity of the antioxidant enzyme catalase in the brain of aged mice. These effects of AI were also confirmed in aged rats (24 months old). Altogether, the present findings indicate that AI can induce neuroprotective effects on age-related alterations in neurobehavioral functions and exerts neurotrophic up-regulatory and anti-apoptotic properties in aged animals. PMID:26087462

  3. Effects of voluntary wheel running on LPS-induced sickness behavior in aged mice.

    PubMed

    Martin, Stephen A; Pence, Brandt D; Greene, Ryan M; Johnson, Stephanie J; Dantzer, Robert; Kelley, Keith W; Woods, Jeffrey A

    2013-03-01

    Peripheral stimulation of the innate immune system with LPS causes exaggerated neuroinflammation and prolonged sickness behavior in aged mice. Regular moderate intensity exercise has been shown to exert anti-inflammatory effects that may protect against inappropriate neuroinflammation and sickness in aged mice. The purpose of this study was to test the hypothesis that voluntary wheel running would attenuate LPS-induced sickness behavior and proinflammatory cytokine gene expression in ~22-month-old C57BL/6J mice. Mice were housed with a running wheel (VWR), locked-wheel (Locked), or no wheel (Standard) for 10 weeks, after which they were intraperitoneally injected with LPS across a range of doses (0.02, 0.08, 0.16, 0.33 mg/kg). VWR mice ran on average 3.5 km/day and lost significantly more body weight and body fat, and increased their forced exercise tolerance compared to Locked and Shoebox mice. VWR had no effect on LPS-induced anorexia, adipsia, weight-loss, or reductions in locomotor activity at any LPS dose when compared to Locked and Shoebox groups. LPS induced sickness behavior in a dose-dependent fashion (0.33>0.02 mg/kg). Twenty-four hours post-injection (0.33 mg/kg LPS or Saline) we found a LPS-induced upregulation of whole brain TNFα, IL-1β, and IL-10 mRNA, and increased IL-1β and IL-6 in the spleen and liver; these effects were not attenuated by VWR. We conclude that VWR does not reduce LPS-induced exaggerated or prolonged sickness behavior in aged animals, or 24h post-injection (0.33 mg/kg LPS or Saline) brain and peripheral proinflammatory cytokine gene expression. The necessity of the sickness response is critical for survival and may outweigh the subtle benefits of exercise training in aged animals.

  4. Small for gestational age as a predictor of behavioral and learning problems in twins.

    PubMed

    Rooney, Rosanna; Hay, David; Levy, Florence

    2003-02-01

    The study examines the effects of being born small for gestational age (SGA) on rates of behavioral problems in twins and siblings, utilising data from the Australian Twin Study of disruptive behavior disorders in twins and their siblings. Participants were 3944 twins and their siblings who were assessed at two intervals three years apart. At the first assessment (1991), they ranged between 4 and 12 years of age. Items assessing Attention Deficit/Hyperactivity Disorder were based on DSM-III-R criteria (Time 1) and DSM-IV criteria (Time 2). Other measures included history of speech and reading therapy, demographic information and obstetric and neonatal history. Results indicated that both male and female twins, who were extremely growth restricted (small for gestational age up to the third percentile-WGA3) showed more inattention, and poorer speech and reading scores. The effects were greater for males. Male twins who were small for gestation age, up to the 10th percentile, were more likely to have a DSM-IV diagnosis of Inattention. Implications of these results included WGA3 male twins being at a "triple disadvantage" for subsequent behavioral and learning problems, in that being male, being a twin and being small for gestational age are all significant factors. Recommendations are made for early intervention for low birthweight male twins. The study is consistent with recent follow-up studies of very-low-birthweight singletons, indicating male disadvantage in cognitive outcome. While there is some genetic component to SGA, it does constitute a potentially major contribution to common environmental effects that must be considered in twin-based genetic analyses. PMID:12626228

  5. The Developmental Course of Illicit Substance Use from Age 12 to 22: Links with Depressive, Anxiety, and Behavior Disorders at Age 18

    ERIC Educational Resources Information Center

    Lansford, Jennifer E.; Erath, Stephen; Yu, Tianyi; Pettit, Gregory S.; Dodge, Kenneth A.; Bates, John E.

    2008-01-01

    Background: Previous theory and research suggest links between substance use and externalizing behavior problems, but links between substance use and internalizing problems are less clear. The present study sought to understand concurrent links among diagnoses of substance use disorders, internalizing disorders, and behavior disorders at age 18 as…

  6. Developmental Risk and Young Children’s Regulatory Strategies: Predicting Behavior Problems at Age Five

    PubMed Central

    Gerstein, Emily D.; Arbona, Anita Pedersen y; Crnic, Keith A.; Ryu, Ehri; Baker, Bruce L.; Blacher, Jan

    2013-01-01

    Children with early developmental delays are at heightened risk for behavior problems and comorbid psychopathology. This study examined the trajectories of regulatory capabilities and their potentially mediating role in the development of behavior problems for children with and without early developmental delays. A sample of 231 children comprised of 137 typically developing children and 94 children with developmental delays were examined during mildly frustrating laboratory tasks across the preschool period (ages 3–5). Results indicated that children with delays had greater use of maladaptive strategies (distraction, distress venting) and lower use of adaptive strategies (constructive coping) than typically developing children. For both groups, strategies had similar rates of growth across time; maladaptive strategies decreased and adaptive strategies increased. The intercept of strategy use, but not the slope, was found to mediate the relation between developmental risk and externalizing behaviors. Findings support that dysregulation, rather than the developmental risk, may be responsible for the high levels of comorbid psychopathology. PMID:21107675

  7. Importance of age on the dynamic mechanical behavior of intertubular and peritubular dentin.

    PubMed

    Ryou, Heonjune; Romberg, Elaine; Pashley, David H; Tay, Franklin R; Arola, Dwayne

    2015-02-01

    An experimental evaluation of human coronal dentin was performed using nanoscopic dynamic mechanical analysis (nanoDMA). The primary objectives were to quantify any unique changes in mechanical behavior of intertubular and peritubular dentin with age, and to evaluate the microstructure and mechanical behavior of the mineral deposited within the lumens. Specimens of coronal dentin were evaluated by nanoDMA using single indents and in scanning mode via scanning probe microscopy. Results showed that there were no significant differences in the storage modulus or complex modulus between the two age groups (18-25 versus 54-83 yrs) for either the intertubular or peritubular tissue. However, there were significant differences in the dampening behavior between the young and old dentin, as represented in the loss modulus and tanδ responses. For both the intertubular and peritubular components, the capacity for dampening was significantly lower in the old group. Scanning based nanoDMA showed that the tubules of old dentin exhibit a gradient in elastic behavior, with decrease in elastic modulus from the cuff to the center of tubules filled with newly deposited mineral.

  8. Age at earliest reported memory: associations with personality traits, behavioral health, and repression.

    PubMed

    Spirrison, C L; McCarley, N G

    2001-09-01

    The present study examined relationships between the age at earliest memory and the personality traits and behavioral health of 107 undergraduates. Participants answered questions on their earliest memory and completed the Myers-Briggs Type Indicator (MBTI) and a medical history form. Analyses indicated that continuous scores on two MBTI scales (Sensing-Intuition and Judging-Perceiving) were inversely related to age at earliest memory as were participant's self-reported drug and alcohol problems, emotional and psychological symptoms, accident rates, physical symptoms, and satisfaction with health. Respondents who reported first memories at or after 7 years of age (i.e., approximately 1 SD above the mean age at recalled memory) were classified as repressors. Repressors scored in the Sensing and Judging directions on the MBTI and reported significantly fewer emotional symptoms, accidents, psychological symptoms, and less health satisfaction than nonrepressors. Results are consistent with the age at earliest memory and repression literature and support the use of earliest memory age as an index of repression. PMID:11575624

  9. Altered Phase Behavior in Membranes of Aging Dry Pollen May Cause Imbibitional Leakage.

    PubMed Central

    Van Bilsen, DGJL.; Hoekstra, F. A.; Crowe, L. M.; Crowe, J. H.

    1994-01-01

    Aging of dry pollen has been shown to coincide with increases of free fatty acids and lysophospholipids. These compounds reduce the integrity of hydrated liposomes made from isolated pollen phospholipids but do not lead to their total destruction. However, a massive, instantaneous leakage occurs upon imbibition of dry cattail pollen (Typha latifolia) that has aged to the point of complete loss of viability. To resolve the apparent discrepancy in stability between hydrated and dry membranes, the lyotropic phase behavior of two liposome systems containing lysophospholipid (12 mol%) was studied with differential scanning calorimetry and Fourier transform infrared spectroscopy. In both systems dehydration caused phase separation of the lipids. Fourier transform infrared data concerning phase behavior of isolated membranes from aging pollen and of membranes in situ did not show phase separations, probably because the assay technique was not sufficiently sensitive to detect them. However, aging of the pollen resulted in a permanent increase in the gel-to-liquid crystalline phase transition temperature (Tm) of isolated membranes and in a broadening of the transition in situ. We conclude that the increase in Tm of hydrated membranes may be more closely related to the leakage. PMID:12232157

  10. AGING BEHAVIOR OF VITON O-RING SEALS IN THE 9975 SHIPPING PACKAGE

    SciTech Connect

    Skidmore, E.; Daugherty, W.; Hoffman, E.; Dunn, K.; Bellamy, S.

    2012-01-13

    The Savannah River Site (SRS) is storing plutonium (Pu) materials in the K-Area Materials Storage (KAMS) facility. The Pu materials were packaged according to the DOE-STD-3013 standard and shipped to the SRS in Type B 9975 packages. The robust 9975 shipping package was not designed for long-term product storage, but it is a specified part of the storage configuration and the KAMS facility safety basis credits the 9975 design with containment. Within the 9975 package, nested stainless steel containment vessels are closed with dual O-ring seals based on Viton{reg_sign} GLT or GLT-S fluoroelastomer. The aging behavior of the O-ring compounds is being studied to provide the facility with advanced notice of nonconformance and to develop life prediction models. A combination of field surveillance, leak testing of surrogate fixtures aged at bounding service temperatures, and accelerated-aging methodologies based on compression stress-relaxation and oxygen consumption analysis is being used to evaluate seal performance. A summary of the surveillance program relative to seal aging behavior is presented.

  11. Damage Mechanisms of Filled Siloxanes for Predictive Multiscale Modeling of Aging Behavior

    SciTech Connect

    Balazs, B; Maxwell, R; de Teresa, S; Dinh, L; Gee, R

    2002-04-02

    Predictions of component performance versus lifetime are often risky for complex materials in which there may be many underlying aging or degradation mechanisms. In order to develop more accurate predictive models for silica-filled siloxane components, we are studying damage mechanisms over a broad range of size domains, linked together through several modeling efforts. Atomistic and molecular dynamic modeling has elucidated the chemistry of the silica filler to polymer interaction, as this interaction plays a key role in this material's aging behavior. This modeling work has been supported by experimental data on the removal of water from the silica surface, the effect of the surrounding polymer on this desiccation, and on the subsequent change in the mechanical properties of the system. Solid State NMR efforts have characterized the evolution of the polymer and filler dynamics as the material is damaged through irradiation or desiccation. These damage signatures have been confirmed by direct measurements of changes in polymer crosslink density and filler interaction as measured by solvent swelling, and by mechanical property tests. Data from the changes at these molecular levels are simultaneously feeding the development of age-aware constitutive models for polymer behavior. In addition, the microstructure of the foam, including under load, has been determined by Computed Tomography, and this data is being introduced into Finite Element Analysis codes to allow component level models. All of these techniques are directed towards the incorporation of molecular and microstructural aging signatures into predictive models for overall component performance.

  12. Changes in dissolved organic carbon of soil amendments with aging: effect on pesticide adsorption behavior.

    PubMed

    Cox, Lucia; Fernandes, M Conceicao; Zsolnay, Adam; Hermosín, M Carmen; Cornejo, Juan

    2004-09-01

    The effect of aging in the soil of three organic amendments (OAs), one liquid (LF) and two solid ones (SF and AL), has been investigated and related to changes in soil adsorption of metalaxyl and tricyclazole. LF and AL have very high dissolved organic carbon (DOC) contents with low humification index values, whereas SF has a low DOC content but the highest amounts of highly humified material. All OAs increased the adsorption of tricyclazole, whereas adsorption of metalaxyl decreased in soils amended with LF and AL, due to competition with DOC for mineral adsorption sites. With aging, DOC from SF amended soils is not significantly affected and neither is adsorption behavior. On the contrary, the great reduction of DOC from LF and AL with aging has been shown to affect adsorption of metalaxyl and tricyclazole, and this effect is dependent on the pesticide, the nature of the DOC, and the type of soil, in particular its clay mineralogy.

  13. A behavioral stages model of classical (Pavlovian) conditioning: application to cognitive aging.

    PubMed

    Powell, D A

    1999-01-01

    In the present article, it is argued that a five-stage sequential model of the behavioral and neurophysiological events that occur when organisms are exposed to signals predicting significant events suggests that classical conditioning produces multiple memory traces involving both excitatory and inhibitory processes. Further, these multiple brain structures and associated neurophysiological mechanisms are beginning to be understood; thus, using Pavlovian conditioning techniques to study aging and cognitive functions may provide insights into which brain structures or mechanisms are responsible for more general age-related declines in associative learning and memory. The evidence for this model is briefly reviewed and studies suggesting age-related effects on classical conditioning of various response systems are described within the context of the brain structures implicated by the model.

  14. A new perspective on behavioral inconsistency and neural noise in aging: compensatory speeding of neural communication

    PubMed Central

    Hong, S. Lee; Rebec, George V.

    2012-01-01

    This paper seeks to present a new perspective on the aging brain. Here, we make connections between two key phenomena of brain aging: (1) increased neural noise or random background activity; and (2) slowing of brain activity. Our perspective proposes the possibility that the slowing of neural processing due to decreasing nerve conduction velocities leads to a compensatory speeding of neuron firing rates. These increased firing rates lead to a broader distribution of power in the frequency spectrum of neural oscillations, which we propose, can just as easily be interpreted as neural noise. Compensatory speeding of neural activity, as we present, is constrained by the: (A) availability of metabolic energy sources; and (B) competition for frequency bandwidth needed for neural communication. We propose that these constraints lead to the eventual inability to compensate for age-related declines in neural function that are manifested clinically as deficits in cognition, affect, and motor behavior. PMID:23055970

  15. Influence of slip system hardening assumptions on modeling stress dependence of work hardening

    NASA Astrophysics Data System (ADS)

    Miller, Matthew; Dawson, Paul

    1997-11-01

    Due to the discrete directional nature of processes such as crystallographic slip, the orientation of slip planes relative to a fixed set of loading axes has a direct effect on the magnitude of the external load necessary to induce dislocation motion (yielding). The effect such geometric or textural hardening has on the macroscopic flow stress can be quantified in a polycrystal by the average Taylor factor M¯. Sources of resistance to dislocation motion such as interaction with dislocation structures, precipitates, and grain boundaries, contribute to the elevation of the critically resolved shear strength τcrss. In continuum slip polycrystal formulations, material hardening phenomena are reflected in the slip system hardness equations. Depending on the model, the hardening equations and the mean field assumption can both affect geometric hardening through texture evolution. In this paper, we examine continuum slip models and focus on how the slip system hardening model and the mean field assumption affect the stress-strain response. Texture results are also presented within the context of how the texture affects geometric hardening. We explore the effect of employing slip system hardnesses averaged over different size scales. We first compare a polycrystal simulation employing a single hardness per crystal to one using a latent hardening formulation producing distinct slip system hardnesses. We find little difference between the amplitude of the single hardness and a crystal-average of the latent hardening values. The geometric hardening is different due to the differences in the textures predicted by each model. We also find that due to the high degree of symmetry in an fcc crystal, macroscopic stress-strain predictions using simulations employing crystal- and aggregateaveraged hardnesses are nearly identical. We find this to be true for several different mean field assumptions. An aggregate-averaged hardness may be preferred in light of the difficulty

  16. Dietary and behavioral interventions protect against age related activation of caspase cascades in the canine brain.

    PubMed

    Snigdha, Shikha; Berchtold, Nicole; Astarita, Giuseppe; Saing, Tommy; Piomelli, Daniele; Cotman, Carl W

    2011-01-01

    Lifestyle interventions such as diet, exercise, and cognitive training represent a quietly emerging revolution in the modern approach to counteracting age-related declines in brain health. Previous studies in our laboratory have shown that long-term dietary supplementation with antioxidants and mitochondrial cofactors (AOX) or behavioral enrichment with social, cognitive, and exercise components (ENR), can effectively improve cognitive performance and reduce brain pathology of aged canines, including oxidative damage and Aβ accumulation. In this study, we build on and extend our previous findings by investigating if the interventions reduce caspase activation and ceramide accumulation in the aged frontal cortex, since caspase activation and ceramide accumulation are common convergence points for oxidative damage and Aβ, among other factors associated with the aged and AD brain. Aged beagles were placed into one of four treatment groups: CON--control environment/control diet, AOX--control environment/antioxidant diet, ENR--enriched environment/control diet, AOX/ENR--enriched environment/antioxidant diet for 2.8 years. Following behavioral testing, brains were removed and frontal cortices were analyzed to monitor levels of active caspase 3, active caspase 9 and their respective cleavage products such as tau and semaphorin7a, and ceramides. Our results show that levels of activated caspase-3 were reduced by ENR and AOX interventions with the largest reduction occurring with combined AOX/ENR group. Further, reductions in caspase-3 correlated with reduced errors in a reversal learning task, which depends on frontal cortex function. In addition, animals treated with an AOX arm showed reduced numbers of cells expressing active caspase 9 or its cleavage product semaphorin 7A, while ENR (but not AOX) reduced ceramide levels. Overall, these data demonstrate that lifestyle interventions curtail activation of pro-degenerative pathways to improve cellular health and are the

  17. Static Strain Aging Behavior of a Manganese-Silicon Steel After Single and Multi-stage Straining

    NASA Astrophysics Data System (ADS)

    Seraj, P.; Serajzadeh, S.

    2016-03-01

    In this work, static strain aging behavior of an alloy steel containing high amounts of silicon and manganese was examined while the influences of initial microstructure and pre-strain on the aging kinetics were evaluated as well. The rate of strain aging in a low carbon steel was also determined and compared with that occurred in the alloy steel. The rates of static strain aging in the steels were defined at room temperature and at 95 °C by means of double-hit tensile testing and hardness measurements. In addition, three-stage aging experiments at 80 °C were carried out to estimate aging behavior under multi-pass deformation processing. The results showed that in-solution manganese and silicon atoms could significantly affect the aging behavior of the steel and reduce the kinetics of static strain aging as compared to the low carbon steel. The initial microstructure also played an important role on the aging behavior. The rapidly cooled steel having mean ferrite grain size of 9.7 μm showed the least aging susceptibility index during the aging experiments. Accordingly, the activation energies for static strain aging were calculated as 93.2 and 85.7 kJ/mole for the alloy steel having fine and coarse ferrite-pearlite structures, respectively while it was computed as 79.1 kJ/mole for the low carbon steel with ferrite mean grain size of about 16.2 μm.

  18. Family Emotional Climate and Sibling Relationship Quality: Influences on Behavioral Problems and Adaptation in Preschool-Aged Children

    ERIC Educational Resources Information Center

    Modry-Mandell, Kerri L.; Gamble, Wendy C.; Taylor, Angela R.

    2007-01-01

    We examined the impact of family emotional climate and sibling relationship quality on behavioral problems and adaptation in preschool-aged children. Participants were 63 mothers with a preschool-aged child enrolled in a Southern Arizona Head Start Program. Siblings were identified as children closest in age to target child. Mothers of…

  19. Phenomenological modeling of hardening and thermal recovery in metals

    NASA Technical Reports Server (NTRS)

    Chan, K. S.; Lindholm, U. S.; Bodner, S. R.

    1988-01-01

    Modeling of hardening and thermal recovery in metals is considered within the context of unified elastic-viscoplastic theories. Specifically, the choices of internal variables and hardening measures, and the resulting hardening response obtained by incorporating saturation-type evolution equations into two general forms of the flow law are examined. Based on the analytical considerations, a procedure for delineating directional and isotropic hardening from uniaxial hardening data has been developed for the Bodner-Partom model and applied to a nickel-base superalloy, B1900 + Hf. Predictions based on the directional hardening properties deduced from the monotonic loading data are shown to be in good agreement with results of cyclic tests.

  20. Aerobic exercise prevents age-dependent cognitive decline and reduces anxiety-related behaviors in middle-aged and old rats.

    PubMed

    Pietrelli, A; Lopez-Costa, J; Goñi, R; Brusco, A; Basso, N

    2012-01-27

    Recent research involving human and animals has shown that aerobic exercise of moderate intensity produces the greatest benefit on brain health and behavior. In this study we investigated the effects on cognitive function and anxiety-related behavior in rats at different ages of aerobic exercise, performed regularly throughout life. We designed an aerobic training program with the treadmill running following the basic principles of human training, and assuming that rats have the same physiological adaptations. The intensity was gradually adjusted to the fitness level and age, and maintained at 60-70% of maximum oxygen consumption (max.VO(2)). In middle age (8 months) and old age (18 months), we studied the cognitive response with the radial maze (RM), and anxiety-related behaviors with the open field (OF) and the elevated plus maze (EPM). Aerobically trained (AT) rats had a higher cognitive performance measured in the RM, showing that exercise had a cumulative and amplifier effect on memory and learning. The analysis of age and exercise revealed that the effects of aerobic exercise were modulated by age. Middle-aged AT rats were the most successful animals; however, the old AT rats met the criteria more often than the middle-aged sedentary controls (SC), indicating that exercise could reverse the negative effects of sedentary life, partially restore the cognitive function, and protect against the deleterious effects of aging. The results in the OF and EPM showed a significant decrease in key indicators of anxiety, revealing that age affected most of the analyzed variables, and that exercise had a prominent anxiolytic effect, particularly strong in old age. In conclusion, our results indicated that regular and chronic aerobic exercise has time and dose-dependent, neuroprotective and restorative effects on physiological brain aging, and reduces anxiety-related behaviors.

  1. Impaired burrowing is the most prominent behavioral deficit of aging htau mice.

    PubMed

    Geiszler, Philippine Camilla; Barron, Matthew Richard; Pardon, Marie-Christine

    2016-08-01

    htau mice are deficient of murine tau but express all six human tau isoforms, leading to gradual tau misprocessing and aggregation in brain areas relevant to Alzheimer's disease. While histopathological changes in htau mice have been researched in the past, we focused here on functional consequences of human tau accumulation. htau mice and their background controls - murine tau knock-out (mtau(-/-)) and C57Bl/6J mice - underwent a comprehensive trial battery to investigate species-specific behavior, locomotor activity, emotional responses, exploratory traits, spatial and recognition memory as well as acquisition, retention and extinction of contextual fear at two, four, six, nine and twelve months of age. In htau mice, tau pathology was already present at two months of age, whereas deficits in food burrowing and spatial working memory were first noted at four months of age. At later stages the presence of human tau on a mtau(-/-) background appeared to guard cognitive performance; as mtau(-/-) but not htau mice differed from C57Bl/6J mice in the food burrowing, spontaneous alternation and object discrimination tasks. Aging mtau(-/-) mice also exhibited increased body mass and locomotor activity. These data highlight that reduced food-burrowing performance was the most robust aspect of the htau phenotype with aging. htau and mtau(-/-) deficits in food burrowing pointed at the necessity of intact tau systems for daily life activities. While some htau and mtau(-/-) deficits overlap, age differences between the two genotypes may reflect distinct functional effects and compared to C57Bl/6J mice, the htau phenotype appeared stronger than the mtau(-/-) phenotype at young ages but milder with aging. PMID:27167086

  2. "Deviance Proneness" and Adolescent Smoking 1980 versus 2001: Has There Been a "Hardening" of Adolescent Smoking?

    ERIC Educational Resources Information Center

    Chassin, Laurie; Presson, Clark; Morgan-Lopez, Antonio; Sherman, Steven J.

    2007-01-01

    In a midwestern community sample, we tested for evidence of "hardening" of adolescent cigarette smoking between 1980 and 2001 by comparing adolescent smokers and nonsmokers at these two times on measures indicative of "deviance proneness" in Jessor and Jessor's [Jessor, R., & Jessor, S. L. (1977). "Problem behavior and psychosocial development: A…

  3. Ethnic identity and risky health behaviors in school-age Mexican-American children.

    PubMed

    Love, Ashley S; Yin, Zenong; Codina, Edward; Zapata, Jesse T

    2006-06-01

    The study examined the relationship between ethnic identity and risky health behaviors in 1,892 Mexican-American students (M age= 14.6, SD= 1.35; 50.3% male) in South Texas. The Ethnic Identity Scale assessed ethnic identity and questions from the Youth Risk Behavior Survey measured risky health behaviors (mixed use of alcohol and drugs, heavy drinking, driving under the influence, regular marijuana use, regular cigarette smoking, lack of regular exercise, not eating breakfast regularly, and carrying a gun or knife to school). Logistic regression tested the relationships between ethnic identity and report of risky health behaviors controlling for potential confounders (sex, free school lunch status, grade, and self-reported school grade). Adjusted odds ratio (AOR) and confidence intervals were calculated. Results indicated that being associated with Mexican-American cultural identity was significantly associated with a decreased mixed use of alcohol and drugs (AOR= .97), heavy drinking (AOR= .98), and regular marijuana use (AOR= .97). A stronger ethnic identity was protective against engaging in risky health behaviors among these Mexican-American adolescents.

  4. Diet, age, and prior injury status differentially alter behavioral outcomes following concussion in rats.

    PubMed

    Mychasiuk, Richelle; Hehar, Harleen; van Waes, Linda; Esser, Michael J

    2015-01-01

    Mild traumatic brain injury (mTBI) or concussion affects a large portion of the population and although many of these individuals recover completely, a small subset of people experience lingering symptomology and poor outcomes. Little is known about the factors that affect individual susceptibility or resilience to poor outcomes after mTBI and there are currently no biomarkers to delineate mTBI diagnosis or prognosis. Based upon the growing literature associated with caloric intake and altered neurological aging and the ambiguous link between repetitive mTBI and progressive neurodegeneration, the current study was designed to examine the effect of a high fat diet (HFD), developmental age, and repetitive mTBI on behavioral outcomes following a mTBI. In addition, telomere length was examined before and after experimental mTBI. Sprague Dawley rats were maintained on a HFD or standard rat chow throughout life (including the prenatal period) and then experienced an mTBI/concussion at P30, P30 and P60, or only at P60. Behavioral outcomes were examined using a test battery that was administered between P61-P80 and included; beam-walking, open field, elevated plus maze, novel context mismatch, Morris water task, and forced swim task. Animals with a P30 mTBI often demonstrated lingering symptomology that was still present during testing at P80. Injuries at P30 and P60 rarely produced cumulative effects, and in some tests (i.e., beam walking), the first injury may have protected the brain from the second injury. Exposure to the high fat diet exacerbated many of the behavioral deficits associated with concussion. Finally, telomere length was shortened following mTBI and was influenced by the animal's dietary intake. Diet, age at the time of injury, and the number of prior concussion incidents differentially contribute to behavioral deficits and may help explain individual variations in susceptibility and resilience to poor outcomes following an mTBI.

  5. Thermoelastic constitutive equations for chemically hardening materials

    NASA Technical Reports Server (NTRS)

    Shaffer, B. W.; Levitsky, M.

    1974-01-01

    Thermoelastic constitutive equations are derived for a material undergoing solidification or hardening as the result of a chemical reaction. The derivation is based upon a two component model whose composition is determined by the degree of hardening, and makes use of strain-energy considerations. Constitutive equations take the form of stress rate-strain rate relations, in which the coefficients are time-dependent functions of the composition. Specific results are developed for the case of a material of constant bulk modulus which undergoes a transition from an initial liquidlike state into an isotropic elastic solid. Potential applications are discussed.

  6. Radiation Hardened Electronics for Space Environments (RHESE)

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Adams, James H.; Frazier, Donald O.; Patrick, Marshall C.; Watson, Michael D.; Johnson, Michael A.; Cressler, John D.; Kolawa, Elizabeth A.

    2007-01-01

    Radiation Environmental Modeling is crucial to proper predictive modeling and electronic response to the radiation environment. When compared to on-orbit data, CREME96 has been shown to be inaccurate in predicting the radiation environment. The NEDD bases much of its radiation environment data on CREME96 output. Close coordination and partnership with DoD radiation-hardened efforts will result in leveraged - not duplicated or independently developed - technology capabilities of: a) Radiation-hardened, reconfigurable FPGA-based electronics; and b) High Performance Processors (NOT duplication or independent development).

  7. 'Work-Hardenable' Ductile Bulk Metallic Glass

    SciTech Connect

    Das, Jayanta; Eckert, Juergen; Tang Meibo; Wang Weihua; Kim, Ki Buem; Baier, Falko; Theissmann, Ralf

    2005-05-27

    Usually, monolithic bulk metallic glasses undergo inhomogeneous plastic deformation and exhibit poor ductility (<1%) at room temperature. We present a new class of bulk metallic glass, which exhibits high strength of up to 2265 MPa together with extensive 'work hardening' and large ductility of 18%. Significant increase in the flow stress was observed during deformation. The 'work-hardening' capability and ductility of this class of metallic glass is attributed to a unique structure correlated with atomic-scale inhomogeneity, leading to an inherent capability of extensive shear band formation, interactions, and multiplication of shear bands.

  8. Windows of vulnerability: maternal separation, age, and fluoxetine on adolescent depressive-like behavior in rats.

    PubMed

    Freund, N; Thompson, B S; Denormandie, J; Vaccarro, K; Andersen, S L

    2013-09-26

    Early exposure to stressful life events plays a significant role in adolescent depression. Clinical studies have identified a number of factors that increase the risk of depression, including sex of the subject, duration of the stressor, and genetic polymorphisms that elevate serotonin levels. In this study we used the maternal separation (MS) model to investigate to what extent these factors interacted during development to manifest in depressive-like behavior in male and female rats. The triadic model of learned helplessness parses depressive-like behavior into aspects of controllable, uncontrollable, and motivational behaviors. This model was used to investigate how the timing of MS between the ages of postnatal day (P) 2-9 and P9-16 interacted with either simultaneous vehicle (saline; 1ml/kg; i.p.) or fluoxetine (10mg/kg) exposure, which was used to enhance serotonin levels; these experiments also compared the effect of a vehicle injection during these developmental periods to a no injection control. Vehicle injections alone increased helplessness in the controllable condition in male rats when injected between P9-16 only, and did not interact further with MS. MS at both ages decreased controllability in male adolescents; females demonstrated an increase in controllability after MS. Elevated serotonin at P2-9 increased escape latencies in male and female control and MS subjects. Fluoxetine exposure at P9-16 increased helplessness in controls. Fluoxetine decreased helplessness in MS males independent of age, but increases helplessness in MS females. This study highlights the importance of age of MS (MS between P2-9 increases helplessness in males more than females), the duration of the stressor (previous results show females are effected by longer MS [P2-20], but not shorter [this study]), and that elevated serotonin increases escape latencies to a greater extent in females. PMID:23850503

  9. Inflammatory insult during pregnancy accelerates age-related behavioral and neurobiochemical changes in CD-1 mice.

    PubMed

    Li, Xue-Yan; Wang, Fang; Chen, Gui-Hai; Li, Xue-Wei; Yang, Qi-Gang; Cao, Lei; Yan, Wen-Wen

    2016-06-01

    Data shows that inflammation during pregnancy significantly exerts a long-term influence on offspring, such as increasing the risk of adult cognition decline in animals. However, it is unclear whether gestational inflammation affects the neurobehavioral and neurobiochemical outcomes in the mother-self during aging. In this study, pregnant CD-1 mice intraperitoneally received lipopolysaccharide (LPS) in two doses (25 and 50 g/kg, respectively) or normal saline daily during gestational days 15-17. At the age of 15 months, a battery of behavioral tasks was employed to evaluate their species-typical behaviors, sensorimotor ability, anxiety levels, and spatial learning and memory abilities. An immunohistochemical method was utilized preliminarily to detect neurobiochemical indicators consisting of amyloid-β, phosphorylated tau, presynaptic proteins synaptotagmin-1 and syntaxin-1, glial fibrillary acidic protein (GFAP), and histone-4 acetylation on the K8 site (H4K8ac). The behavioral results showed that LPS exposure during pregnancy exacerbated a decline in 15-month-old CD-1 mice's abilities to nest, their sensorimotor and spatial learning and memory capabilities, and increased their anxiety levels. The neurobiochemical results indicated that gestational LPS exposure also intensified age-related hippocampal changes, including increased amyloid-β42, phosphorylated tau, synaptotagmin-1 and GFAP, and decreased syntaxin-1 and H4K8ac. Our results suggested that the inflammatory insult during pregnancy could be an important risk factor for the development of Alzheimer's disease, and the H4K8 acetylation might play an important role in the underlying mechanism. This study offers a perspective for improving strategies that support healthy development and successful aging.

  10. Forced limb-use enhanced neurogenesis and behavioral recovery after stroke in the aged rats.

    PubMed

    Qu, H L; Zhao, M; Zhao, S S; Xiao, T; Song, C G; Cao, Y P; Jolkkonen, J; Zhao, C S

    2015-02-12

    Constraint-induced movement therapy (CIMT) after stroke enhances not only functional reorganization but also structural plasticity of the brain in the adult rats. We examined whether forced limb-use which mimicked CIMT could influence ischemia-induced neurogenesis, apoptosis and behavioral recovery in the aged rats. Aged rats were divided into a sham group, an ischemia group, and an ischemia group with forced limb-use. Focal cerebral ischemia was induced by injection of endothelin-1. Forced limb-use began on post-stroke day 7 by fitting a plaster cast around the unimpaired upper limbs of rats for 3 weeks. Behavioral recovery was evaluated by tapered/ledged beam-walking test on postoperative day 32. The expression of doublecortin, neuronal nuclei, glial fibrillary acidic protein and Iba-1 were measured by single or double immunohistochemistry, and apoptosis was measured by TdT-mediated dUTP-biotin nick-end labeling (TUNEL) assay. The production of neuroblasts in the subventricular zone (SVZ) was significantly increased after stroke. Forced limb-use enhanced the proliferation of newborn neurons in the SVZ, as well as increased the long-term survival of newborn neurons. Furthermore, forced limb-use suppressed apoptosis and improved the motor functions after stroke in the aged rats. Forced limb-use exerted few effects on inflammation. Neither the number nor dendritic complexity of newborn granule cells in the hippocampus was affected by forced limb-use. Forced limb-use is effective in enhancing neurogenesis and behavioral recovery after stroke even in the aged rats. PMID:25463522

  11. Effects of diet & behavioral enrichment on free fatty acids in the aged canine brain

    PubMed Central

    Snigdha, Shikha; Astarita, Giuseppe; Piomelli, Daniele; Cotman, Carl W.

    2012-01-01

    Despite several recent studies suggesting that dysregulation of brain lipid metabolism might contribute to the mechanisms of aging and Alzheimer’s disease (AD), lipid metabolism has not been evaluated extensively in the aging brain. Here, we use a lipidomic approach to demonstrate that antioxidants plus mitochondrial cofactors treatment, either alone or in combination with behavioral enrichment, attenuates lipid abnormalities in the frontal cortices of aged canine in a manner correlated with cognitive scores. Our analyses revealed that the levels of free palmitoleic acid and nervonic acid were decreased in frontal cortices of aged dogs (n=5-6/group) treated with antioxidant compared to the control group. The monounsaturated/saturated fatty acid ratio, also known as ‘desaturation index’ - an ex-vivo indicator of stearoyl-CoA desaturase activity, was also reduced in the frontal cortex of dogs treated with antioxidants compared to control groups. Increased palmitoleic acid levels and desaturation index were positively correlated with increased reversal learning errors and decreased cognitive performance. In conclusion, our study indicates that the addition of antioxidants and mitochondrial cofactors to the regular diet alters the composition of free fatty acids in the aged brain. Together with data showing increased palmitoleic acid levels in AD patients, our data suggest that reducing palmitoleic acid levels and desaturation index in the brain may be associated with improved cognitive performance. PMID:22183056

  12. Aging Behavior of the EPDM O-Rings in the H1616 Shipping Package

    SciTech Connect

    Daugherty, W.; Stefek, T.; Skidmore, E.

    2015-06-09

    The H1616 shipping package is used within the DOE complex for shipping tritium reservoirs. The annual recertification frequency can create logistical difficulties with other constraints on the timing of shipments; thus, a longer re-certification period is desirable. The ethylene propylene diene monomer (EPDM) O-rings used in the H1616 shipping package are being aged and tested at the Savannah River National Laboratory (SRNL) to provide a technical basis for extending the annual maintenance of the H1616 shipping package. H1616 EPDM O-rings are being aged at elevated temperature, and tested for degradation in mechanical properties, compression stress relaxation (CSR) behavior, and leak performance. Mechanical properties of aged O-rings show significant degradation can occur, but an inert atmosphere (argon backfill) greatly reduces the rate of degradation. The CSR behavior of O-rings was evaluated in air at 79 to 177 °C. These collective data were used to develop a predictive model for extrapolation of CSR behavior to relevant service temperatures (<67 °C). O-rings were also aged in H1616 Containment Vessels (CV) in an inert atmosphere at 71 to 149 °C. The vessels are helium leak tested periodically to determine if they continue to remain leak-tight. The vessel tests provide a solid demonstration that the H1616 O-rings will remain leak-tight at temperatures up to 113 °C for up to approximately 2.3 years. Significantly longer periods of leak-tight service are expected at the lower temperatures actually experienced in service. The predictive model developed from the CSR data conservatively indicates a service life of ~5 years at 67 °C. Although the relationship between CSR behavior and leak-tight performance has not been established for this design, the CSR predictions for this O-ring are conservative relative to leak-tight performance. Based on the collective data developed to date, SRNL has recommended that the maintenance interval for the H1616 package be

  13. Effects of physical aging on long-term behavior of composites

    NASA Technical Reports Server (NTRS)

    Brinson, L. Catherine

    1993-01-01

    The HSCT plane, envisioned to have a lifetime of over 60,000 flight hours and to travel at speeds in excess of Mach 2, is the source of intensive study at NASA. In particular, polymer matrix composites are being strongly considered for use in primary and secondary structures due to their high strength to weight ratio and the options of property tailoring. However, an added difficulty in the use of polymer based materials is that their properties change significantly over time, especially at the elevated temperatures that will be experienced during flight, and prediction of properties based on irregular thermal and mechanical loading is extremely difficult. This study focused on one aspect of long-term polymer composite behavior: physical aging. When a polymer is cooled to below its glass transition temperature, the material is not in thermodynamic equilibrium and the free volume and enthalpy evolve over time to approach their equilibrium values. During this time, the mechanical properties change significantly and this change is termed physical aging. This work begins with a review of the concepts of physical aging on a pure polymer system. The effective time theory, which can be used to predict long term behavior based on short term data, is mathematically formalized. The effects of aging to equilibrium are proven and discussed. The theory developed for polymers is then applied first to a unidirectional composite, then to a general laminate. Comparison to experimental data is excellent. It is shown that the effects of aging on the long-term properties of composites can be counter-intuitive, stressing the importance of the development and use of a predictive theory to analyze structures.

  14. Behavioral responses to and brain distribution of morphine in mature adult and aged mice

    SciTech Connect

    Burton, C.K.; Ho, I.K.; Hoskins, B.

    1986-03-01

    Mature adult (3-6 mo old) and aged (2 yr old) male ICR mice were injected with 10 to 100 mg/kg morphine, s.c. The ED50 values for running behavior (as measured using Stoelting activity monitors and having each mouse serve as its own control) representing 5 times control activity was approximately 7.5 mg/kg for aged mice and approximately 17.5 mg/kg for the mature adults. The ED50 values for analgesia 1 hr after morphine administration using the tail-flick method (max. response time = 8 sec) were approx. 70 mg/kg for the aged mice and 15 mg/kg for the mature adults. One hour after injecting /sup 3/H-morphine at doses of 30 and 100 mg/kg, 0.13 and 0.14% of the doses appeared in brains of aged and mature adult mice, respectively. Regional distribution of the morphine was the same for both age groups. Expressed as percent of total brain morphine, it was as follows: cortex, 30%; midbrain, 18%; cerebellum, 17%; medulla, 12%; pons, 9%; striatum, 8% and periaqueductal gray, 6%. Expressed as g morphine/g tissue for the 2 doses, the distribution was; periaqueductal gray, 30 and 80; striatum, 9 and 34; medulla, 6 and 20 pons; 5 and 19; cerebellum, 4 and 13; midbrain 2.5 and 8.5 and cortex, 2 and 8. These results suggest that the differences in response to morphine by the two age groups were due to age-related differences in opioid receptor populations and/or affinities.

  15. Psychological and behavioral disease during developmental age: the importance of the alliance with parents

    PubMed Central

    Gatta, Michela; Ramaglioni, Elisabetta; Lai, Jessica; Svanellini, Lorenza; Toldo, Irene; Del Col, Lara; Salviato, Cinzia; Spoto, Andrea; Antonio, Battistella Pier

    2009-01-01

    The aim of the study is to analyze the clinician’s alliance with parents during the diagnostic process in relation to therapeutic compliance and clinical evolution of individuals aged 0–11 years. The sample was formed by 84 individuals aged 0 to 11 years (18 < 6 years, 66 aged 6 to 11 years; 62 males and 22 females) who came to the Neuropsychiatric Unit for Children and Adolescents for a consultation regarding psychorelational and behavioral problems. Neuropsychiatric consultation took place in five diagnostic interviews with child and parents, separately. The last session was devoted to communication of psychiatric diagnosis (according to ICD 10) and therapeutic suggestions, if any. The clinician’s relationship with parents and patients’ participation were evaluated in terms of collaboration and quality of interaction, on the basis of pre-established criteria. Data about patients’ therapeutic compliance and clinical outcome were collected during a follow-up visit eight months after the last session. Results suggest that the better the alliance between parents and clinician, the higher the therapeutic compliance and the likelihood of a positive outcome for patients. Our data suggest that good communication with parents benefits child patients, both in terms of response to the parents’ need to report their children’s worrying behavior and as a response to the discomfort expressed by children when they come in for consultation. PMID:19898668

  16. Age-of-Onset or Behavioral Sub-Types? A Prospective Comparison of Two Approaches to Characterizing the Heterogeneity within Antisocial Behavior

    ERIC Educational Resources Information Center

    Burt, S. Alexandra; Donnellan, M. Brent; Iacono, William G.; McGue, Matt

    2011-01-01

    There are two common approaches to sub-typing the well-documented heterogeneity within antisocial behavior: age-of-onset (i.e., childhood-onset versus adolescence-onset; see "Moffitt" 1993) and behavioral (i.e., physical aggression versus non-aggressive rule-breaking). These approaches appear to be associated, such that aggression is more…

  17. Strength, Hardening, and Failure Observed by In Situ TEM Tensile Testing.

    PubMed

    Kiener, Daniel; Kaufmann, Petra; Minor, Andrew M

    2012-11-01

    We present in situ transmission electron microscope tensile tests on focused ion beam fabricated single and multiple slip oriented Cu tensile samples with thicknesses in the range of 100-200 nm. Both crystal orientations fail by localized shear. While failure occurs after a few percent plastic strain and limited hardening in the single slip case, the multiple slip samples exhibit extended homogenous deformation and necking due to the activation of multiple dislocation sources in conjunction with significant hardening. The hardening behavior at 1% plastic strain is even more pronounced compared to compression samples of the same orientation due to the absence of sample taper and the interface to the compression platen. Moreover, we show for the first time that the strain rate sensitivity of such FIB prepared samples is an order of magnitude higher than that of bulk Cu.

  18. Analysis of the infrared spectrum and microstructure of hardened cement paste

    SciTech Connect

    Gao, X.F.; Lo, Y.; Tam, C.M.; Chung, C.Y. )

    1999-06-01

    Phase transformation was found in hardened cement paste exposed to dynamic loading caused by typhoon and the normal static-dynamic loading. The concrete samples were obtained from a 20-year-old residential building. The bonding characteristics and microstructure of the hardened cement paste with different loading history have been carefully studied using scanning electron microscopy analysis and infrared spectrum technique. The scanning electron microscopy micrographs indicate that there is a morphological difference in the concrete microstructure. The infrared spectrum analysis has provided information for understanding the phase transformation characteristics of the primary bonds and secondary bonds. This has led to the establishment of a microscopic model describing the correlation between the behavior of the hydrate lime and the properties of the hardened cement paste.

  19. Mechanisms of Neutron Irradiation Hardening in Impurity-Doped Ferritic Alloys

    NASA Astrophysics Data System (ADS)

    Nishiyama, Y.; Liu, X. Y.; Kameda, J.

    2008-05-01

    Mechanisms of neutron irradiation hardening in phosphorus (P)-doped, sulfur (S)-doped, and copper (Cu)-doped ferritic alloys have been studied by applying a rate theory to the temperature dependence of the yield strength. Hardening behavior induced by neutron irradiation at various temperatures (473 to 711 K) is characterized in terms of the variations in athermal stress and activation energy for plasticity controlled by precipitation or solid solution, and kink-pair formation with the content and type of impurities. In P-doped alloys, neutron irradiation below 563 K brings about a remarkable increase in the athermal stress and activation energy, due to the dispersion of fine (˜1.7-nm) P-rich precipitates that is more extensive than that for the Cu-rich precipitates reported in irradiated steel. During neutron irradiation above 668 K, precipitation hardening occurs to some extent in Cu-doped and S-doped alloys, compared to small or negligible hardening in the P-doped alloys. In alloys with a low to moderate content of various dissolved impurities subjected to high-temperature irradiation, the formation of kink pairs becomes considerably difficult. Differing dynamic interactions of dissolved and precipitated impurities, i.e., P and Cu, with the nucleation and growth of dislocations are discussed, giving rise to irradiation hardening.

  20. SEU hardening of CMOS memory circuit

    NASA Technical Reports Server (NTRS)

    Whitaker, S.; Canaris, J.; Liu, K.

    1990-01-01

    This paper reports a design technique to harden CMOS memory circuits against Single Event Upset (SEU) in the space environment. A RAM cell and Flip Flop design are presented to demonstrate the method. The Flip Flop was used in the control circuitry for a Reed Solomon encoder designed for the Space Station.

  1. Extraordinary strain hardening by gradient structure

    PubMed Central

    Wu, XiaoLei; Jiang, Ping; Chen, Liu; Yuan, Fuping; Zhu, Yuntian T.

    2014-01-01

    Gradient structures have evolved over millions of years through natural selection and optimization in many biological systems such as bones and plant stems, where the structures change gradually from the surface to interior. The advantage of gradient structures is their maximization of physical and mechanical performance while minimizing material cost. Here we report that the gradient structure in engineering materials such as metals renders a unique extra strain hardening, which leads to high ductility. The grain-size gradient under uniaxial tension induces a macroscopic strain gradient and converts the applied uniaxial stress to multiaxial stresses due to the evolution of incompatible deformation along the gradient depth. Thereby the accumulation and interaction of dislocations are promoted, resulting in an extra strain hardening and an obvious strain hardening rate up-turn. Such extraordinary strain hardening, which is inherent to gradient structures and does not exist in homogeneous materials, provides a hitherto unknown strategy to develop strong and ductile materials by architecting heterogeneous nanostructures. PMID:24799688

  2. Relationships between Gross Motor Abilities and Problematic Behaviors of Handicapped Children in Different Age Groups

    PubMed Central

    Uesugi, Masayuki; Araki, Tomoko; Fujii, Shun; Itotani, Keisuke; Otani, Yoshitaka; Seiichi, Takemasa

    2014-01-01

    [Purpose] In this study, we examined problematic behaviors of independent-walking and non-independent-walking handicapped children in the infant, school child and adolescent development phases, using the Japanese version of the Aberrant Behavior Checklist (ABC-J) to determine if such behaviors relate to their gross motor abilities. [Subjects and Methods] The subjects were 86 handicapped children who were receiving physical therapy. The subjects were classified into three groups by age. Using the Gross Motor Function Classification System (GMFCS), each group was further divided into an independent-walking group and non-independent-walking group. Thirteen physical therapists and 8 occupational therapists, who were treating the subject children, rated the subjects using the ABC-J. [Results] Significant differences were observed between the independent-walking and the non-independent-walking groups in the stereotypy and lethargy scores of infants. [Conclusion] For schoolchildren and adolescents, no significant differences were observed between the independent-walking and the non-independent-walking groups in their problematic behavior scores. PMID:25540495

  3. Relationships between Gross Motor Abilities and Problematic Behaviors of Handicapped Children in Different Age Groups.

    PubMed

    Uesugi, Masayuki; Araki, Tomoko; Fujii, Shun; Itotani, Keisuke; Otani, Yoshitaka; Seiichi, Takemasa

    2014-12-01

    [Purpose] In this study, we examined problematic behaviors of independent-walking and non-independent-walking handicapped children in the infant, school child and adolescent development phases, using the Japanese version of the Aberrant Behavior Checklist (ABC-J) to determine if such behaviors relate to their gross motor abilities. [Subjects and Methods] The subjects were 86 handicapped children who were receiving physical therapy. The subjects were classified into three groups by age. Using the Gross Motor Function Classification System (GMFCS), each group was further divided into an independent-walking group and non-independent-walking group. Thirteen physical therapists and 8 occupational therapists, who were treating the subject children, rated the subjects using the ABC-J. [Results] Significant differences were observed between the independent-walking and the non-independent-walking groups in the stereotypy and lethargy scores of infants. [Conclusion] For schoolchildren and adolescents, no significant differences were observed between the independent-walking and the non-independent-walking groups in their problematic behavior scores.

  4. Aging and emotional memory: the co-occurrence of neurophysiological and behavioral positivity effects.

    PubMed

    Langeslag, Sandra J E; van Strien, Jan W

    2009-06-01

    The positivity effect is a trend for adults to increasingly process positive and/or decreasingly process negative information compared with other information with advancing age. The positivity effect has been observed with behavioral measures, such as in attention and memory tests, and with measures of neurophysiological activity, such as in amygdala activation and the late positive potential (LPP). In this study, it was investigated whether these behavioral and neurophysiological positivity effects co-occur. The electroencephalogram of younger (19-26 years) and older (65-82 years) adults was recorded while they encoded unpleasant, neutral, and pleasant pictures for retrieval in free and cued recall tests. Positivity effects occurred in the late LPP amplitude (700-1,000 ms) and in the free recall test, with negativity biases in younger adults and no biases in older adults. The occurrence of a valence bias in the LPP was substantially but nonsignificantly correlated with the occurrence of a similar valence bias in memory in the older adults. In conclusion, neurophysiological and behavioral positivity effects appear to co-occur, a finding that awaits expansion using different neurophysiological and behavioral measures. PMID:19485614

  5. 'Fire hardening' spear wood does slightly harden it, but makes it much weaker and more brittle.

    PubMed

    Ennos, Antony Roland; Chan, Tak Lok

    2016-05-01

    It is usually assumed that 'fire hardening' the tips of spears, as practised by hunter-gatherers and early Homo spp., makes them harder and better suited for hunting. This suggestion was tested by subjecting coppiced poles of hazel to a fire-hardening process and comparing their mechanical properties to those of naturally seasoned poles. A Shore D hardness test showed that fire treatment slightly increased the hardness of the wood, but flexural and impact tests showed that it reduced the strength and work of fracture by 30% and 36%, respectively. These results suggest that though potentially slightly sharper and more durable, fire-hardened tips would actually be more likely to break off when used, as may have been the case with the earliest known wooden tool, the Clacton spear. Fire might first have been used to help sharpen the tips of spears, and fire-hardening would have been a mostly negative side effect, not its primary purpose.

  6. 'Fire hardening' spear wood does slightly harden it, but makes it much weaker and more brittle.

    PubMed

    Ennos, Antony Roland; Chan, Tak Lok

    2016-05-01

    It is usually assumed that 'fire hardening' the tips of spears, as practised by hunter-gatherers and early Homo spp., makes them harder and better suited for hunting. This suggestion was tested by subjecting coppiced poles of hazel to a fire-hardening process and comparing their mechanical properties to those of naturally seasoned poles. A Shore D hardness test showed that fire treatment slightly increased the hardness of the wood, but flexural and impact tests showed that it reduced the strength and work of fracture by 30% and 36%, respectively. These results suggest that though potentially slightly sharper and more durable, fire-hardened tips would actually be more likely to break off when used, as may have been the case with the earliest known wooden tool, the Clacton spear. Fire might first have been used to help sharpen the tips of spears, and fire-hardening would have been a mostly negative side effect, not its primary purpose. PMID:27194289

  7. Large time behavior in a nonlinear age-dependent population dynamics problem with spatial diffusion.

    PubMed

    Langlais, M

    1988-01-01

    In this work we analyze the large time behavior in a nonlinear model of population dynamics with age-dependence and spatial diffusion. We show that when t----+ infinity either the solution of our problem goes to 0 or it stabilizes to a nontrivial stationary solution. We give two typical examples where the stationary solutions can be evaluated upon solving very simple partial differential equations. As a by-product of the extinction case we find a necessary condition for a nontrivial periodic solution to exist. Numerical computations not described below show a rapid stabilization.

  8. Adoptive and Nonadoptive Mother–Child Behavioral Interaction: A Comparative Study at 4 Years of Age

    PubMed Central

    Suwalsky, Joan T. D.; Padilla, Christina M.; Yuen, Cynthia X.; Horn, E. Parham; Bradley, Alexandra L.; Putnick, Diane L.; Bornstein, Marc H.

    2016-01-01

    Comparable samples of low-risk adopted and nonadopted children and mothers were observed during 3 tasks at age 4 years. Quality of mother-child interactions, child level of functioning in 4 domains, and maternal parenting satisfaction and social support were assessed. Adopted children were as competent as nonadopted children on measures of developmental functioning. Both groups of mothers expressed high satisfaction and support as parents. However, ratings of child, maternal, and dyadic behavior when interacting were all lower for adoptive dyads than for nonadoptive dyads, and adoptive dyads with boys accounted for the maternal and dyadic group differences. PMID:27134518

  9. [Gender and age differences in the cognitive, psychophysiological, and behavioral responses of social anxiety in adolescence].

    PubMed

    Inglés, Cándido J; Piqueras, José A; García-Fernández, José M; García-López, Luis J; Delgado, Beatriz; Ruiz-Esteban, Cecilia

    2010-08-01

    The aim of this study was to analyze gender and age differences in adolescents' social anxiety in the factor scores of the Social Phobia subscale from the Social Phobia and Anxiety Inventory (SP-SPAI): Social Interactions, Focus of Attention, Cognitive and Somatic Symptoms and Avoidance and Escape Behaviors. The sample consisted of 2,543 students of Secondary Education between 12 and 17 years. Results are shown for the general sample (N= 2,543) and for the sample of adolescents classified as high social anxiety group (n= 317). Regarding the first group, girls obtained higher total scores on the Social Phobia scale and on all factors except for Avoidance and Escape (d= .32 - .35). Concerning the high anxiety group, the analyses revealed that boys avoid and escape from social situations more frequently than girls (d= .23). No age differences were found in the factor scores for any of the two samples.

  10. Coffee, but not caffeine, has positive effects on cognition and psychomotor behavior in aging.

    PubMed

    Shukitt-Hale, Barbara; Miller, Marshall G; Chu, Yi-Fang; Lyle, Barbara J; Joseph, James A

    2013-12-01

    The complex mixture of phytochemicals in fruits and vegetables provides protective health benefits, mainly through additive and/or synergistic effects. The presence of several bioactive compounds, such as polyphenols and caffeine, implicates coffee as a potential nutritional therapeutic in aging. Moderate (three to five cups a day) coffee consumption in humans is associated with a significant decrease in the risk of developing certain chronic diseases. However, the ability of coffee supplementation to improve cognitive function in aged individuals and the effect of the individual components in coffee, such as caffeine, have not been fully evaluated. We fed aged rats (19 months) one of five coffee-supplemented diets (0, 0.165, 0.275, 0.55, and 0.825% of the diet) for 8 weeks prior to motor and cognitive behavior assessment. Aged rats supplemented with a 0.55% coffee diet, equivalent to ten cups of coffee, performed better in psychomotor testing (rotarod) and in a working memory task (Morris water maze) compared to aged rats fed a control diet. A diet with 0.55% coffee appeared to be optimal. The 0.165% coffee-supplemented group (three cups) showed some improvement in reference memory performance in the Morris water maze. In a subsequent study, the effects of caffeine alone did not account for the performance improvements, showing that the neuroprotective benefits of coffee are not due to caffeine alone, but rather to other bioactive compounds in coffee. Therefore, coffee, in achievable amounts, may reduce both motor and cognitive deficits in aging.

  11. Effects of age and exposure to heavy particles on a behavioral measure of anxiety

    NASA Astrophysics Data System (ADS)

    Rabin, B. M.; Joseph, J. A.; Shukitt-Hale, B.; Carrihill-Knoll, K. L.; Carey, A.; Foster, B. C.

    On forthcoming exploratory class missions astronauts will be expected to function in novel and possibly dangerous environments This requirement may produce anticipatory fear or anxiety Previous research has shown that exposure to HZE particles such as those experienced on missions beyond the protection provided by the magnetic shield of the earth can affect the performance of the organism on a variety of tasks In addition research has shown that there is an interaction between age and exposure to heavy particles on a variety of behavioral tasks such that older organisms are more susceptible to the deleterious effects of irradiation Because there are changes in exploration-induced anxiety as a function of age it is possible that exposure to HZE particles will also affect a middle-aged astronaut s ability to respond appropriately in anxiety producing situations The present experiment utilized the elevated plus-maze to evaluate the effects of age and exposure to HZE particle radiation on anxiety Fischer-344 rats 2 7 12 and 16 months of age at the time of irradiation were exposed to 56 Fe particles 1 GeV n 0 25-2 00 Gy in the NASA Space Radiation Laboratory at Brookhaven National Laboratory Control rats at each age were not irradiated At the time of testing the rats were 3- 11- 13- and 20-months old respectively Anxiety was studied using an elevated plus-maze The maze is composed of four arms in the shape of a sign placed 90 cm above the floor Two of the arms are enclosed and two of the arms are open The amount of

  12. Modelling of the aging behavior of polyamide 12 powder during laser melting process

    NASA Astrophysics Data System (ADS)

    Drummer, Dietmar; Wudy, Katrin; Drexler, Maximilian

    2015-05-01

    Concerning individualization, the requirements to products have increased. Additive manufacturing technologies, such as selective laser melting allow manufacturing of complex parts without tools and forms. Due to this additive manufacturing processes comply, in opposite to conventional techniques, with these increased demands on processing technology. Due to the high temperature during processing, a degradation of the used plastic powder occurs. The non-molten material in the building chamber, the so-called partcake, can be removed after building from the finished component and reused for another process. To realize reproducible part properties refreshing of partcake powder with 30 up to 50 % virgin powder is necessary. However, these refreshing strategies lead to varying component properties due to an undefined aging state. Previous investigations on oven aged powder for selective laser melting showed for short periods of storage near the melting point thermally induced post condensation is the predominate aging effect. Due to post condensation the molecular weight and thus the viscosity increases. This paper focuses on the modeling of the post condensation process to define the aging state of polyamide 12 powder in laser melting process. Therefore the rheological behavior of PA 12 powder in dependency of time and temperature is investigated. Isothermal viscosity measurements are conducted in order to describe the post condensation reaction with a model. With knowledge of the kinetics of the post condensation reaction the state of aging can be predicted in a second step. Thus expected useful life of the powder can be calculated in dependency of the building chamber temperature. These results are then compared with viscosity values of defined aged PA 12 powder to validate the determined model.

  13. Culturally Tailored, Family-Centered, Behavioral Obesity Intervention for Latino-American Preschool-aged Children

    PubMed Central

    Gesell, Sabina B.; Po’e, Eli K.; Escarfuller, Juan; Tempesti, Tommaso

    2012-01-01

    OBJECTIVE: To test the effect of a culturally tailored, family-centered, short-term behavioral intervention on BMI in Latino-American preschool-aged children. METHODS: In a randomized controlled trial, 54 parent–child dyads were allocated to the intervention and 52 dyads were allocated to an alternative school-readiness program as the control condition. Parent–child dyads were eligible if the parent self-defined Latino, was at least 18 years old, had a 2- to 6-year-old child not currently enrolled in another healthy lifestyle program, had a valid telephone number, and planned on remaining in the city for the next 6 months. The Salud Con La Familia (Health with the Family) program consisted of 12 weekly 90-minute skills-building sessions designed to improve family nutritional habits and increase physical activity. Both programs were conducted in a community recreation center serving an urban neighborhood of mostly Spanish-speaking residents. RESULTS: Forty-two percent of participating preschool-aged children were overweight or obese. Controlling for child age, gender, and baseline BMI, the effect of the treatment condition on postintervention absolute BMI was B = –0.59 (P < .001). The intervention effect seemed to be strongest for obese children. CONCLUSIONS: A skills-building, culturally tailored intervention involving parent–child dyads changed short-term early growth patterns in these Latino-American preschool-aged children. Examining long-term effects would be a prudent next step. PMID:22869834

  14. Effect of biochar aging on surface characteristics and adsorption behavior of dialkyl phthalates.

    PubMed

    Ghaffar, Abdul; Ghosh, Saikat; Li, Fangfang; Dong, Xudong; Zhang, Di; Wu, Min; Li, Hao; Pan, Bo

    2015-11-01

    The implications of biochar aging regarding their material properties as well as their interactions with other contaminants are not vivid. We report the role of biochar aging on sorption behavior of di-alkyl phthalates (PAEs). Biochars used in this study were produced from peanut-shell and their aging was simulated by chemical oxidation. The structural composition and morphology of the obtained biochars, before and after oxidation with HNO3/H2SO4, were analyzed by element composition, XPS, DRIFT, and SEM/EDX. Several experimental results unequivocally showed oxygen enrichment in the mixed acid treated samples compared to their precursors. Despite surface area reduction and pore destruction, increased PAEs sorption on oxidized biochar surfaces portrayed existence of strong PAEs binding sites. The adsorption of PAEs on oxidized biochar surface is a cumulative influence of hydrophobic interactions and pi-pi electron donor-acceptor interactions. Our results suggest that imminent aging of biochar upon environmental exposure may change their sorbent properties. PMID:26281762

  15. Weight status and bullying behaviors among Chinese school-aged children.

    PubMed

    Liu, Xiaoqun; Chen, Gui; Yan, Junxia; Luo, Jiayou

    2016-02-01

    This study was to examine the relationship between measured weight status and three experiences as victims, bullies and bully-victims. The participants were 10,587 Chinese school-aged students (girls: 5,527, boys: 5,060) who ranged in age from 7 to 18 years old. Height and weight were measured. Bullying behavior was obtained by one-to-one interview in 7-10 years older students and group-administered surveys in 11-18 years older students. The results showed that, obese girls were more likely to be victimized (OR=1.73, CI: 1.16-2.59) compared to normal students. For boys, obesity was not associated with victimization, but obese boys (OR=1.45, CI: 1.04-2.03), especially 7-13 years old boys (OR=1.98, CI: 1.35-2.90) were more likely to bully others; obese boys also were more likely to be victim/bullies (OR=1.67, CI: 1.05-2.64). Weight victimization in Chinese school-aged children is not as common as in the west countries, but obese girls clearly realize more victimization, and obese younger boys show obvious aggression. Related departments should provide specific intervention for school bullying according students' weight status, age and gender. PMID:26773898

  16. Water maze training in aged rats: effects on brain metabolic capacity and behavior.

    PubMed

    Villarreal, J S; Gonzalez-Lima, F; Berndt, J; Barea-Rodriguez, E J

    2002-06-01

    The effects of Morris water maze training on brain metabolism and behavior were compared between aged (20-22 months) and young (2-4 months) Fischer 344 male rats. Each group had yoked controls, which swam the same amount of time as the trained rats but without the platform. This was followed after 9 days by quantitative histochemical mapping of brain cytochrome oxidase, the terminal enzyme for cellular respiration. The aged rats spent a significantly lower percent of time in the correct quadrant and had a longer latency to escape to the hidden platform, relative to the young rats. Metabolic differences between trained aged and young rats were found in regions related to escape under stress: perirhinal cortex, basolateral amygdala and lateral habenula; and vestibular nuclei that guide orientation in three-dimensional space. These differences were not found in the yoked swimming rats. The results suggest that, at the time point investigated, water maze training in aged Fischer 344 rats produces altered oxidative energy metabolism in task-relevant limbic and vestibular regions.

  17. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Hardening and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be...

  18. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Hardening and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be...

  19. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Hardening and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be...

  20. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Hardening and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be...

  1. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Hardening and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be...

  2. The Origins of Mental Toughness – Prosocial Behavior and Low Internalizing and Externalizing Problems at Age 5 Predict Higher Mental Toughness Scores at Age 14

    PubMed Central

    Sadeghi Bahmani, Dena; Hatzinger, Martin; Gerber, Markus; Lemola, Sakari; Clough, Peter J.; Perren, Sonja; von Klitzing, Kay; von Wyl, Agnes; Holsboer-Trachsler, Edith; Brand, Serge

    2016-01-01

    Background: The concept of mental toughness (MT) has gained increasing importance among groups other than elite athletes by virtue of its psychological importance and explanatory power for a broad range of health-related behaviors. However, no study has focused so far on the psychological origins of MT. Therefore, the aims of the present study were: to explore, to what extent the psychological profiles of preschoolers aged five were associated with both (1) MT scores and (2) sleep disturbances at age 14, and 3) to explore possible gender differences. Method: Nine years after their first assessment at age five (preschoolers), a total of 77 adolescents (mean age: 14.35 years; SD = 1.22; 42% females) took part in this follow-up study. At baseline, both parents and teachers completed the Strengths and Difficulties Questionnaire (SDQ), covering internalizing and externalizing problems, hyperactivity, negative peer relationships, and prosocial behavior. At follow-up, participants completed a booklet of questionnaires covering socio-demographic data, MT, and sleep disturbances. Results: Higher prosocial behavior, lower negative peer relationships, and lower internalizing and externalizing problems at age five, as rated by parents and teachers, were associated with self-reported higher MT and lower sleep disturbances at age 14. At age 14, and relative to males, females had lower MT scores and reported more sleep disturbances. Conclusion: The pattern of results suggests that MT traits during adolescence may have their origins in the pre-school years. PMID:27605919

  3. The Origins of Mental Toughness – Prosocial Behavior and Low Internalizing and Externalizing Problems at Age 5 Predict Higher Mental Toughness Scores at Age 14

    PubMed Central

    Sadeghi Bahmani, Dena; Hatzinger, Martin; Gerber, Markus; Lemola, Sakari; Clough, Peter J.; Perren, Sonja; von Klitzing, Kay; von Wyl, Agnes; Holsboer-Trachsler, Edith; Brand, Serge

    2016-01-01

    Background: The concept of mental toughness (MT) has gained increasing importance among groups other than elite athletes by virtue of its psychological importance and explanatory power for a broad range of health-related behaviors. However, no study has focused so far on the psychological origins of MT. Therefore, the aims of the present study were: to explore, to what extent the psychological profiles of preschoolers aged five were associated with both (1) MT scores and (2) sleep disturbances at age 14, and 3) to explore possible gender differences. Method: Nine years after their first assessment at age five (preschoolers), a total of 77 adolescents (mean age: 14.35 years; SD = 1.22; 42% females) took part in this follow-up study. At baseline, both parents and teachers completed the Strengths and Difficulties Questionnaire (SDQ), covering internalizing and externalizing problems, hyperactivity, negative peer relationships, and prosocial behavior. At follow-up, participants completed a booklet of questionnaires covering socio-demographic data, MT, and sleep disturbances. Results: Higher prosocial behavior, lower negative peer relationships, and lower internalizing and externalizing problems at age five, as rated by parents and teachers, were associated with self-reported higher MT and lower sleep disturbances at age 14. At age 14, and relative to males, females had lower MT scores and reported more sleep disturbances. Conclusion: The pattern of results suggests that MT traits during adolescence may have their origins in the pre-school years.

  4. Investigation of the Influence Factors on Distortion in Induction-Hardened Steel Shafts Manufactured from Cold-Drawn Rod

    NASA Astrophysics Data System (ADS)

    Dong, Juan; Epp, Jeremy; Rocha, Alexandre da Silva; Nunes, Rafael Menezes; Zoch, Hans Werner

    2016-02-01

    In this study, the distortion of steel shafts was investigated before and after induction hardening. Several essential influencing factors in the manufacturing process chain regarding cold drawing, cutting method, notches on the shafts, and induction hardening were analyzed by design of experiment (DoE). Further necessary examinations of microstructures, hardness profile, segregation of chemical composition, and residual stress state were conducted for understanding the distortion behavior. The results of the statistical analysis of the DoE showed that the drawing process is the most important factor influencing distortion. The surface hardening depth of induction hardening is the second main factor. The relationship between inhomogeneities in the work pieces and the distortion was finally discussed.

  5. On constitutive relations at finite strain - Hypo-elasticity and elasto-plasticity with isotropic or kinematic hardening

    NASA Technical Reports Server (NTRS)

    Atluri, S. N.

    1984-01-01

    Nagtegaal and de Jong (1982) have studied stresses generated by simple finite shear in the case of elastic-plastic and rigid-plastic materials which exhibit anisotropic hardening. They reported that the shear stress is oscillatory in time. It was found that the occurrence of such an 'anomaly' is not restricted to anisotropic plasticity. Similar behavior in finite shear may result even in the case of hypoelasticity and classical isotropic hardening plasticity theory. The present investigation is concerned with the central problem of 'generalizing' with respect to the finite strain case, taking into account the constitutive relations of infinitesimal strain theories of classical plasticity with isotropic or kinematic hardening. The problem of hypoelasticity is also considered. It is shown that current controversies surrounding the choice of stress rate in the finite-strain generalizations of the constitutive relations and the anomalies surrounding kinematic hardening plasticity theory are easily resolvable.

  6. Use of Medication Prescribed for Emotional or Behavioral Difficulties among Children Aged 6-17 Years in the United ...

    MedlinePlus

    ... months for emotional or behavioral difficulties varied by poverty level. Among children aged 6–17 years, a ... in families having income below 100% of the poverty level (9.2%) used prescribed medication for emotional ...

  7. Relationships between regulatory temperament dimensions and self-regulatory behaviors at 4 and 6 months of age.

    PubMed

    Aureli, Tiziana; Coppola, Gabrielle; Picconi, Laura; Grazia, Annalisa; Ponzetti, Silvia

    2015-02-01

    The present study focused on relationships between temperament and behavior in early regulation development. Unlike most studies on the topic, we observed infant behavior in a naturalistic playful situation rather than in experimental stressful procedure, and employed temperament measures uniquely reflecting regulatory dispositions rather than a global measure of reactivity. The infant's self-regulatory behaviors were observed at 4 and 6 months during face-to-face interactions and regulatory dimensions were assessed at 4 months. We found that low intensity pleasure and soothability dimensions, related to the infant physical and social experience, respectively, significantly affected regulatory behavior and their influence showed to depend on the infant's age, with the former dimension being influential at the earlier age and the latter being influential when the behavior was observed at the later age. Results are interpreted on the light of a dynamic view of regulation development.

  8. Fetal antiepileptic drug exposure: Adaptive and emotional/behavioral functioning at age 6 years

    PubMed Central

    Cohen, Morris J.; Meador, Kimford J.; Browning, Nancy; May, Ryan; Baker, Gus A.; Clayton-Smith, Jill; Kalayjian, Laura A.; Kanner, Andres; Liporace, Joyce D.; Pennell, Page B.; Privitera, Michael; Loring, David W.

    2014-01-01

    The Neurodevelopmental Effects of Antiepileptic Drugs (NEAD) study is a prospective observational multicenter study in the USA and UK, which enrolled pregnant women with epilepsy on antiepileptic drug (AED) monotherapy from 1999 to 2004. The study aimed to determine if differential long-term neurodevelopmental effects exist across four commonly used AEDs (carbamazepine, lamotrigine, phenytoin, and valproate). In this report, we examine fetal AED exposure effects on adaptive and emotional/behavioral functioning at 6 years of age in 195 children (including three sets of twins) whose parent (in most cases, the mother) completed at least one of the rating scales. Adjusted mean scores for the four AED groups were in the low average to average range for parent ratings of adaptive functioning on the Adaptive Behavior Assessment System—Second Edition (ABAS-II) and for parent and teacher ratings of emotional/behavioral functioning on the Behavior Assessment System for Children (BASC). However, children whose mothers took valproate during pregnancy had significantly lower General Adaptive Composite scores than the lamotrigine and phenytoin groups. Further, a significant dose-related performance decline in parental ratings of adaptive functioning was seen for both valproate and phenytoin. Children whose mothers took valproate were also rated by their parents as exhibiting significantly more atypical behaviors and inattention than those in the lamotrigine and phenytoin groups. Based upon BASC parent and teacher ratings of attention span and hyperactivity, children of mothers who took valproate during their pregnancy were at a significantly greater risk for a diagnosis of ADHD. The increased likelihood of difficulty with adaptive functioning and ADHD with fetal valproate exposure should be communicated to women with epilepsy who require antiepileptic medication. Finally, additional research is needed to confirm these findings in larger prospective study samples, examine

  9. Dislocation Starvation and Exhaustion Hardening in Mo-alloy Nanofibers

    SciTech Connect

    Chisholm, Claire; Bei, Hongbin; Lowry, M. B.; Oh, Jason; Asif, S.A. Syed; Warren, O.; Shan, Zhiwei; George, Easo P; Minor, Andrew

    2012-01-01

    The evolution of defects in Mo alloy nanofibers with initial dislocation densities ranging from 0 to 1.6 1014 m2 were studied using an in situ push-to-pull device in conjunction with a nanoindenter in a transmission electron microscope. Digital image correlation was used to determine stress and strain in local areas of deformation. When they had no initial dislocations the Mo alloy nanofibers suffered sudden catastrophic elongation following elastic deformation to ultrahigh stresses. At the other extreme fibers with a high dislocation density underwent sustained homogeneous deformation after yielding at much lower stresses. Between these two extremes nanofibers with intermediate dislocation densities demonstrated a clear exhaustion hardening behavior, where the progressive exhaustion of dislocations and dislocation sources increases the stress required to drive plasticity. This is consistent with the idea that mechanical size effects ( smaller is stronger ) are due to the fact that nanostructures usually have fewer defects that can operate at lower stresses. By monitoring the evolution of stress locally we find that exhaustion hardening causes the stress in the nanofibers to surpass the critical stress predicted for self-multiplication, supporting a plasticity mechanism that has been hypothesized to account for the rapid strain softening observed in nanoscale bcc materials at high stresses.

  10. Atomistic interpretation of solid solution hardening from spectral analysis.

    PubMed

    Plendl, J N

    1971-05-01

    From analysis of a series of vibrational spectra of ir energy absorption and laser Raman, an attempt is made to interpret solid solution hardening from an atomistic point of view for the system CaF(2)/SrF(2). It is shown to be caused by the combined action of three atomic characteristics, i.e., their changes as a function of composition. They are deformation of the atomic coordination polyhedrons, overlap of the outer electron shells of the atom pairs, and the ratio of the ionic to covalent share of binding. A striking nonlinear behavior of the three characteristics, as a function of composition, gives maximum atomic bond strength to the 55/45 position of the system CaF(2)/SrF(2), in agreement with the measured data of the solid solution hardening. The curve for atomic bond strength, derived from the three characteristics, is almost identical to the curve for measured microhardness data. This result suggests that the atomistic interpretation, put forward in this paper, is correct.

  11. Bullying behaviors among Chinese school-aged youth: a prevalence and correlates study in Guangdong Province.

    PubMed

    Wu, Jie; He, Yuan; Lu, Ciyong; Deng, Xueqing; Gao, Xue; Guo, Lan; Wu, Hong; Chan, Fanfan; Zhou, Ying

    2015-02-28

    Bullying among school-aged youth is a common issue worldwide and is increasingly being recognized as an important problem affecting both victims and perpetrators. Most of the bullying studies have been conducted in western countries, and their implications in other regions are limited due to different cultural contexts. The goal of our study is to identify the prevalence of bullying and its correlates school-aged youth in Guangdong province. In total, 1098 (7.1%) students reported having bullied other students, 744 (4.8%) students reported having been bullied by other students and 396 (2.6%) students reported having both bullied other students and been bullied by other students. There was a strong association between bullying others as well as being bullied and suicidal ideations, suicidal attempts, and self-harm behaviors. The prevalence of bullying and its associations with delinquent behaviors warrant the importance of school facility based preventive intervention taking into account both victims and perpetrators. PMID:25510905

  12. Maternal feeding practices and feeding behaviors of Australian children aged 12-36 months.

    PubMed

    Chan, L; Magarey, A M; Daniels, L A

    2011-11-01

    To explore parents' perceptions of the eating behaviors and related feeding practices of their young children. Mothers (N=740) of children aged 12-36 months and born in South Australia were randomly selected by birth date in four 6-month age bands from a centralized statewide database and invited to complete a postal questionnaire. Valid completed questionnaires were returned for 374 children (51% response rate; 54% female). Although mothers generally reported being confident and happy in feeding their children, 23% often worried that they gave their child the right amount of food. Based on a checklist of 36 specified items, 15% of children consumed no vegetables in the previous 24 h, 11% no fruit and for a further 8% juice was the only fruit. Of 12 specified high fat/sugar foods and drinks, 11% of children consumed none, 20% one, 26% two, and 43% three or more. Six of eight child-feeding practices that promote healthy eating behaviors were undertaken by 75% parents 'often' or 'all of the time'. However, 8 of 11 practices that do not promote healthy eating were undertaken by a third of mothers at least 'sometimes'. In this representative sample, dietary quality issues emerge early and inappropriate feeding practices are prevalent thus identifying the need for very early interventions that promote healthy food preferences and positive feeding practices. Such programs should focus not just on the 'what', but also the 'how' of early feeding, including the feeding relationship and processes appropriate to developmental stage. PMID:20872057

  13. Aging Behavior of the Viton® Fluoroelastomer O-Rings in the 9975 Shipping Package

    SciTech Connect

    Daugherty, W.; Mcwilliams, A.; Skidmore, E.

    2015-06-09

    The 9975 Type B shipping package is used within the DOE complex for shipping special nuclear materials. This package is re-certified annually in accordance with Safety Analysis Report requirements. The package is also used at the Savannah River Site as part of the long-term storage configuration of special nuclear materials. As such, the packages do not undergo annual recertification during storage, with uncertainty as to how long some of the package components will meet their functional requirements in the storage environment. The packages are currently approved for up to 15 years storage, and work continues to provide a technical basis to extend that period. This paper describes efforts by the Savannah River National Laboratory (SRNL) to extend the service life estimate of Viton® GLT and GLT-S fluoroelastomer O-rings used in the 9975 shipping package. O-rings of both compositions are undergoing accelerated aging at elevated temperature, and are periodically tested for compression stress relaxation (CSR) behavior and leak performance. The CSR behavior of O-rings was evaluated at temperatures from 79 °C to 177 °C. These collective data were used to develop predictive models for extrapolation of CSR behavior to relevant service temperatures (< 75 °C). O-rings were also aged in Primary Containment Vessel (PCV) fixtures at temperatures ranging from 79 °C to 232 °C. The fixtures are helium leak tested periodically to determine if they remain leak-tight. The PCV fixture tests demonstrate that the 9975 O-rings will remain leak-tight at temperatures up to 149 °C for 3 years or more, and no leak failures have been observed with up to 8 years aging at 93 °C. Significantly longer periods of leak-tight service are expected at the lower temperatures actually experienced in the storage environment. The predictive model developed from the CSR data conservatively indicates a service life of more than 20 years at the bounding temperature of 75 °C. Although the

  14. Diet, age, and prior injury status differentially alter behavioral outcomes following concussion in rats.

    PubMed

    Mychasiuk, Richelle; Hehar, Harleen; van Waes, Linda; Esser, Michael J

    2015-01-01

    Mild traumatic brain injury (mTBI) or concussion affects a large portion of the population and although many of these individuals recover completely, a small subset of people experience lingering symptomology and poor outcomes. Little is known about the factors that affect individual susceptibility or resilience to poor outcomes after mTBI and there are currently no biomarkers to delineate mTBI diagnosis or prognosis. Based upon the growing literature associated with caloric intake and altered neurological aging and the ambiguous link between repetitive mTBI and progressive neurodegeneration, the current study was designed to examine the effect of a high fat diet (HFD), developmental age, and repetitive mTBI on behavioral outcomes following a mTBI. In addition, telomere length was examined before and after experimental mTBI. Sprague Dawley rats were maintained on a HFD or standard rat chow throughout life (including the prenatal period) and then experienced an mTBI/concussion at P30, P30 and P60, or only at P60. Behavioral outcomes were examined using a test battery that was administered between P61-P80 and included; beam-walking, open field, elevated plus maze, novel context mismatch, Morris water task, and forced swim task. Animals with a P30 mTBI often demonstrated lingering symptomology that was still present during testing at P80. Injuries at P30 and P60 rarely produced cumulative effects, and in some tests (i.e., beam walking), the first injury may have protected the brain from the second injury. Exposure to the high fat diet exacerbated many of the behavioral deficits associated with concussion. Finally, telomere length was shortened following mTBI and was influenced by the animal's dietary intake. Diet, age at the time of injury, and the number of prior concussion incidents differentially contribute to behavioral deficits and may help explain individual variations in susceptibility and resilience to poor outcomes following an mTBI. PMID:25270295

  15. Development and validation of a Q-sort procedure to assess temperament and behavior in preschool-age children.

    PubMed

    Buckley, Maureen E; Klein, Daniel N; Durbin, C Emily; Hayden, Elizabeth P; Moerk, Kirstin C

    2002-12-01

    Few broad observational measures of preschool-age children's temperament and behavior currently exist. Studied the Child Temperament and Behavior Q-Set (CTBQ-Set) as a naturalistic observation measure to tap the major domains of temperament and behavior in preschoolers. Pairs of observers rated the behavior of a community sample of preschoolers during 2 independent home visits using q-sort methodology. The CTBQ-Set scales displayed good levels of internal consistency and convergent and discriminant content saturation. The scales displayed good interrater reliability at each observation and moderate test-retest stability between observations. The construct validity of the CTBQ-Set scales was supported by correlations with mothers' ratings of their children's behavior using the Child Behavior Checklist for 2- and 3-year-olds (CBCL/2-3) and the Children's Behavior Questionnaire. The CTBQ-Set shows promise as an observer-reated measure of preschoolers' behavior and temperament in their natural home environment.

  16. Coming of age in an ant colony: cephalic muscle maturation accompanies behavioral development in Pheidole dentata

    NASA Astrophysics Data System (ADS)

    Muscedere, Mario L.; Traniello, James F. A.; Gronenberg, Wulfila

    2011-09-01

    Although several neurobiological and genetic correlates of aging and behavioral development have been identified in social insect workers, little is known about how other age-related physiological processes, such as muscle maturation, contribute to task performance. We examined post-eclosion growth of three major muscles of the head capsule in major and minor workers of the ant Pheidole dentata using workers of different ages with distinct task repertoires. Mandible closer muscle fibers, which provide bite force and are thus critical for the use of the mandibles for biting and load carrying, fill the posterio-lateral portions of the head capsule in mature, older workers of both subcastes. Mandible closer fibers of newly eclosed workers, in contrast, are significantly thinner in both subcastes and grow during at least the next 6 days in minor workers, suggesting this muscle has reduced functionality for a substantial period of adult life and thus constrains task performance capability. Fibers of the antennal muscles and the pharynx dilator, which control antennal movements and food intake, respectively, also increase significantly in thickness with age. However, these fibers are only slightly thinner in newly eclosed workers and attain their maximum thickness over a shorter time span in minors. The different growth rates of these functionally distinct muscles likely have consequences for how adult P. dentata workers, particularly minors, develop their full and diverse task repertoire as they age. Workers may be capable of feeding and interacting socially soon after eclosion, but require a longer period of development to effectively use their mandibles, which enable the efficient performance of tasks ranging from nursing to foraging and defense.

  17. Health Behaviors and Protective Factors of School Students Aged 13-15 Years Old in Four Cities of China

    ERIC Educational Resources Information Center

    Tian, Benchun; Zhang, Wei; Qian, Ling; Lv, Shuhong; Tian, Xiangyang; Xiong, Guanglian; Yan, Weihong; Zhang, Xinwei; Kann, Laura K.; Riley, Leanne

    2007-01-01

    This paper presents baseline data on health behaviors and protective factors among junior middle school students aged 13-15 years old in China for the purpose of developing priorities, establishing programs and policies for school health and youth health and also establishing trends in the prevalence of these behaviors. The 2003 CHINA GSHS…

  18. Genetic and Environmental Mechanisms Underlying Stability and Change in Problem Behaviors at Ages 3, 7, 10, and 12

    ERIC Educational Resources Information Center

    Bartels, M.; van den Oord, E. J. C. G.; Hudziak, J. J,; Rietveld, M. J. H.; van Beijsterveldt, C. E. M.; Boomsma, D. I.

    2004-01-01

    Maternal ratings on internalizing (INT) and externalizing (EXT) behaviors were collected in a large, population-based longitudinal sample. The numbers of participating twin pairs at ages 3, 7, 10, and 12 were 5,602, 5,115, 2,956, and 1,481, respectively. Stability in both behaviors was accounted for by genetic and shared environmental influences.…

  19. Early Developmental and Psychosocial Risks and Longitudinal Behavioral Adjustment Outcomes for Preschool-Age Girls Adopted from China

    ERIC Educational Resources Information Center

    Tan, Tony Xing; Marfo, Kofi; Dedrick, Robert F.

    2010-01-01

    The central goal of this longitudinal study was to examine behavioral adjustment outcomes in a sample of preschool-age adopted Chinese girls. Research examining the effects of institutional deprivation on post-adoption behavioral outcomes for internationally adopted children has been constrained by the frequent unavailability of data on the…

  20. Sleep, Cognition, and Behavioral Problems in School-Age Children: A Century of Research Meta-Analyzed

    ERIC Educational Resources Information Center

    Astill, Rebecca G.; Van der Heijden, Kristiaan B.; Van IJzendoorn, Marinus H.; Van Someren, Eus J. W.

    2012-01-01

    Clear associations of sleep, cognitive performance, and behavioral problems have been demonstrated in meta-analyses of studies in adults. This meta-analysis is the first to systematically summarize all relevant studies reporting on sleep, cognition, and behavioral problems in healthy school-age children (5-12 years old) and incorporates 86 studies…

  1. The Relation of Age, Gender, Ethnicity, and Risk Behaviors to Self-Esteem among Students in Nonmainstream Schools

    ERIC Educational Resources Information Center

    Connor, Jennifer M.; Poyrazli, Senel; Ferrer-Wreder, Laura; Grahame, Kamini Maraj

    2004-01-01

    This cross-sectional study investigated self-esteem in relation to age, gender, ethnicity, and risk behaviors among a sample of nonmainstream students. Participants were 149 students in the 6th to 12th grades from two non-mainstream schools (one charter and one alternative school). Self-esteem and youth risk behaviors were determined by using a…

  2. Social Competence and Behavior Evaluation in Children Ages 3 to 6 Years: The Short Form (SCBE-30).

    ERIC Educational Resources Information Center

    LaFreniere, Peter J.; Dumas, Jean E.

    1996-01-01

    The factor structure and scale characteristics of a shortened version of the Social Competence and Behavior Evaluation Scale (SCBE) are presented for a Quebec (Canada) sample of 910 preschoolers and three U.S. samples totaling 1,736. Also presented are age and gender differences in preschool emotional and behavioral problems. (SLD)

  3. Peer Problems Mediate the Relationship between Developmental Coordination Disorder and Behavioral Problems in School-Aged Children

    ERIC Educational Resources Information Center

    Wagner, Matthias Oliver; Bos, Klaus; Jascenoka, Julia; Jekauc, Darko; Petermann, Franz

    2012-01-01

    The aim of this study was to gain insights into the relationship between developmental coordination disorder, peer problems, and behavioral problems in school-aged children where both internalizing and externalizing behavioral problems were considered. We assumed that the relationship between developmental coordination disorder and…

  4. Mothers' Parenting Behaviors in Families of School-Aged Children with Autism Spectrum Disorder: An Observational and Questionnaire Study

    ERIC Educational Resources Information Center

    Boonen, Hannah; van Esch, Lotte; Lambrechts, Greet; Maljaars, Jarymke; Zink, Inge; Van Leeuwen, Karla; Noens, Ilse

    2015-01-01

    Although parents of children with ASD face specific challenges in parenting, only a few studies have empirically investigated parenting behaviors among these parents. The current study examined differences in parenting behaviors between mothers of school-aged children with ASD (n = 30) and mothers of typically developing children (n = 39), using…

  5. Modeling the mechanical behavior of vertebral trabecular bone: effects of age-related changes in microstructure.

    PubMed

    Silva, M J; Gibson, L J

    1997-08-01

    Age-related reductions in the thickness and number of trabeculae in vertebral trabecular bone have been documented by several workers, yet the relative effects of these changes on mechanical properties are not known. We developed a two-dimensional model of human vertebral trabecular bone and investigated its mechanical behavior using finite element analysis. The stress-strain behavior, failure mode, and strain distributions predicted using the model were consistent with those observed for vertebral trabecular bone under compressive loading. Random reductions in the number of trabeculae reduced the modulus and strength of the models two to five times more than uniform reductions in the thickness of trabeculae that caused the same loss of bone volume. For example, randomly removing longitudinal trabeculae to achieve a reduction in density of 10% reduced the strength by approximately 70%, whereas removing the same amount of bone by uniformly reducing the thickness of the longitudinal trabeculae only reduced the strength by approximately 20%. For a simulation of aged bone, in which the thickness and number of trabeculae were reduced concurrently, the strength was 23% of its intact ("young") value. When the bone mass of the aged model was restored to its intact level by increasing the thickness but not the number of trabeculae, the strength increased by 60%, but was still only 37% of its intact value. These combined findings, based on a two-dimensional, idealized model of vertebral trabecular bone, illustrate the importance of maintaining trabecular number and suggest that it may not be possible to restore bone strength following a period of advanced bone loss if a substantial number of trabeculae have been resorbed. Thus, until treatments exist that can increase trabecular number, the most effective treatment strategy is to prevent the degradation of bone strength by maintaining the number of trabeculae at a healthy level.

  6. Environmental impact to multimedia systems on the example of fingerprint aging behavior at crime scenes

    NASA Astrophysics Data System (ADS)

    Merkel, Ronny; Breuhan, Andy; Hildebrandt, Mario; Vielhauer, Claus; Bräutigam, Anja

    2012-06-01

    In the field of crime scene forensics, current methods of evidence collection, such as the acquisition of shoe-marks, tireimpressions, palm-prints or fingerprints are in most cases still performed in an analogue way. For example, fingerprints are captured by powdering and sticky tape lifting, ninhydrine bathing or cyanoacrylate fuming and subsequent photographing. Images of the evidence are then further processed by forensic experts. With the upcoming use of new multimedia systems for the digital capturing and processing of crime scene traces in forensics, higher resolutions can be achieved, leading to a much better quality of forensic images. Furthermore, the fast and mostly automated preprocessing of such data using digital signal processing techniques is an emerging field. Also, by the optical and non-destructive lifting of forensic evidence, traces are not destroyed and therefore can be re-captured, e.g. by creating time series of a trace, to extract its aging behavior and maybe determine the time the trace was left. However, such new methods and tools face different challenges, which need to be addressed before a practical application in the field. Based on the example of fingerprint age determination, which is an unresolved research challenge to forensic experts since decades, we evaluate the influences of different environmental conditions as well as different types of sweating and their implications to the capturing sensory, preprocessing methods and feature extraction. We use a Chromatic White Light (CWL) sensor to exemplary represent such a new optical and contactless measurement device and investigate the influence of 16 different environmental conditions, 8 different sweat types and 11 different preprocessing methods on the aging behavior of 48 fingerprint time series (2592 fingerprint scans in total). We show the challenges that arise for such new multimedia systems capturing and processing forensic evidence

  7. Evaluation of the nucleation and coarsening kinetic behavior of the secondary hardening carbide of Fe-HCo-10Ni-1Mo-0.16C steel at two chromium levels, using an analytical and modeling approach: Part II

    NASA Astrophysics Data System (ADS)

    Oh, Y.; Machmeier, P. M.; Matuszewski, T.; Ayer, R.

    1997-06-01

    The effect of 1 % Cr addition on the resistivity during preaging and peak aging of an AF1410 based steel was examined by analytical and modeling approaches. The increased kinetics of aging resulting from a chromium addition, due to a variety of complex microstructural changes,was analyzed by Avrami-Mehl and Wert-Zener formulations, which were modified so that the exponent was a function of time. Using a eneralized Avrami equation, it was shown that the nucleation rate, N(t), at short aging times was large but became a rapidly declining function as N(t) approaches zero in a supersaturated system. A mathematical solution, using AF1410 steel carbide growth data at 510 °C, confirmed reported experimental evidence of second-stage carbide nucleation at 1 to 2 h.

  8. Spelling Difficulties in School-Aged Girls with Attention-Deficit/Hyperactivity Disorder: Behavioral, Psycholinguistic, Cognitive, and Graphomotor Correlates

    ERIC Educational Resources Information Center

    Åsberg Johnels, Jakob; Kopp, Svenny; Gillberg, Christopher

    2014-01-01

    Writing difficulties are common among children with attention-deficit/hyperactivity disorder (ADHD), but the nature of these difficulties has not been well studied. Here we relate behavioral, psycholinguistic, cognitive (memory/executive), and graphomotor measures to spelling skills in school-age girls with ADHD (n = 30) and an age-matched group…

  9. Early Childhood Household Smoke Exposure Predicts Less Task-Oriented Classroom Behavior at Age 10.

    PubMed

    Pagani, Linda S; Fitzpatrick, Caroline

    2016-10-01

    Secondhand tobacco smoke is considered a developmental neurotoxicant especially given underdeveloped vital systems in young children. An ecological test of its negative influence on brain development can be made by examining the prospective association between early childhood household smoke exposure and later classroom behavior. Using a longitudinal birth cohort, we examined the unique contribution of household tobacco smoke exposure to children's subsequent classroom engagement at age 10. From child ages 1.5 to 7 years, parents of 2,055 participants from the Quebec Longitudinal Study of Child Development reported on household smoking by themselves and other home occupants. At age 10, fourth-grade teachers reported on the child's classroom engagement. In terms of prevalence, 58% of parents reported that their children were never exposed to smoke in the home, while 34% and 8% of children were exposed to transient and continuous household smoke, respectively. Compared with never exposed children, those who were exposed to transient and continuous household smoke scored 13% and 9% of a standard deviation lower on classroom engagement in fourth grade, standardized B = -.128 (95% confidence interval = -.186, -.069) and standardized B = -.093 (95% confidence interval = -.144, -.043), respectively. Compared with their never exposed peers, children exposed to transient and continuous early childhood household smoke showed proportionately less classroom engagement, which reflects task-orientation, following directions, and working well autonomously and with others. This predisposition poses risks for high school dropout, which from a population health perspective is closely linked with at-risk lifestyle habits and unhealthy outcomes.

  10. A prospective study of young females' sexual subjectivity: associations with age, sexual behavior, and dating.

    PubMed

    Zimmer-Gembeck, Melanie J; Ducat, Wendy H; Boislard-Pepin, Marie-Aude

    2011-10-01

    Sexual self-perceptions are important aspects of sexuality, which can undergo significant change during adolescence and early adulthood. The purpose of this study was to describe these changes among girls (N = 251; ages 16-25) over one year, and to examine associations of sexual self-perceptions (sexual subjectivity) with age, sexual behavior, and romantic status. Sexual body-esteem, perceptions of entitlement to desire and pleasure, sexual efficacy, and sexual self-reflection were investigated as elements of sexual subjectivity. All sexual subjectivity elements were higher among girls who had more sexual experience and/or had steady romantic partners during the study. Perception of entitlement to desire and pleasure increased over time, whereas sexual body-esteem showed the most stability and had minimal associations with sexual or romantic experiences. The greatest increases in sexual subjectivity were found among girls who began the study with the least sociosexual experience and self-reflection also increased for girls who had first coitus after the start of the study. Overall, girls who had sexual intercourse the earliest (before age 16) had the highest sexual subjectivity, but sexual subjectivity increased the most among girls without coital experience or who had more recent first coitus.

  11. Finite-Element Simulation of Conventional and High-Speed Peripheral Milling of Hardened Mold Steel

    NASA Astrophysics Data System (ADS)

    Tang, D. W.; Wang, C. Y.; Hu, Y. N.; Song, Y. X.

    2009-12-01

    A finite-element model (FEM) with the flow stress and typical fracture is used to simulate a hard machining process, which before this work could not adequately represent the constitutive behavior of workpiece material that is usually heat treated to hardness levels above 50 Rockwell C hardness (HRC). Thus, a flow stress equation with a variation in hardness is used in the computer simulation of hard machining. In this article, the influence of the milling speed on the cutting force, chip morphology, effective stress, and cutting temperature in the deformation zones of both conventional and high-speed peripheral milling hardened mold steel is systematically studied by finite-element analysis (FEA). By taking into consideration the importance of material characteristics during the milling process, the similar Johnson-Cook’s constitutive equation with hardened mold steel is introduced to the FEM to investigate the peripheral milling of hardened mold steel. In comparison with the experimental data of the cutting force at various cutting speeds, the simulation result is identical with the measured data. The results indicate that the model can be used to accurately predict the behavior of hardened mold steel in both conventional and high-speed milling.

  12. Radiation-hardened transistor and integrated circuit

    DOEpatents

    Ma, Kwok K.

    2007-11-20

    A composite transistor is disclosed for use in radiation hardening a CMOS IC formed on an SOI or bulk semiconductor substrate. The composite transistor has a circuit transistor and a blocking transistor connected in series with a common gate connection. A body terminal of the blocking transistor is connected only to a source terminal thereof, and to no other connection point. The blocking transistor acts to prevent a single-event transient (SET) occurring in the circuit transistor from being coupled outside the composite transistor. Similarly, when a SET occurs in the blocking transistor, the circuit transistor prevents the SET from being coupled outside the composite transistor. N-type and P-type composite transistors can be used for each and every transistor in the CMOS IC to radiation harden the IC, and can be used to form inverters and transmission gates which are the building blocks of CMOS ICs.

  13. Construction procedures using self hardening fly ash

    NASA Astrophysics Data System (ADS)

    Thornton, S. I.; Parker, D. G.

    1980-07-01

    Fly ash produced in Arkansas from burning Wyoming low sulfur coal is self-hardening and can be effective as a soil stabilizing agent for clays and sands. The strength of soil-self hardening fly ash develops rapidly when compacted immediately after mixing. Seven day unconfined compressive strengths up to 1800 psi were obtained from 20% fly ash and 80% sand mixtures. A time delay between mixing the fly ash with the soil and compaction of the mixture reduced the strength. With two hours delay, over a third of the strength was lost and with four hours delay, the loss was over half. Gypsum and some commercial concrete retarders were effective in reducing the detrimental effect of delayed compaction. Adequate mixing of the soil and fly ash and rapid compaction of the mixtures were found to be important parameters in field construction of stabilized bases.

  14. Laser hardening of diesel engine valve

    SciTech Connect

    Androsov, A.P.; Aleksenko, S.I.; Boyarkin, M.V.; Kusidis, V.G.; Petrov, V.I.

    1988-07-01

    Results are presented of a complex investigation of the effect of laser treatment on the structure and properties of steel 40Kh10S2M and of engine tests with diesel engine valves hardened by the newly devised technology. Results of the investigation of the microstructure of steel 40Kh10S2M, heat-treated by a laser beam, showed that when a specimen is hardened with fusion of the surface layer, it contains two distinct zones of laser action. Results of the effect of laser treatment on the fatigue limit and the wear resistance of the steel and engine tests permit the conclusion that the suggested method of treating valves of internal engine valve gear has good prospects.

  15. Behavioral Autonomy Age Expectations among Mexican-Origin Mother-Daughter Dyads: An Examination of Within-Group Variability

    PubMed Central

    Bámaca-Colbert, Mayra Y.; Umaña-Taylor, Adriana J.; Espinosa-Hernández, Graciela; Brown, Ashley M.

    2011-01-01

    This study examined differences in behavioral autonomy age expectations between Mexican-origin mothers and their adolescent daughters (N = 319 dyads); variability in behavioral autonomy age expectations as a function of nativity and maternal educational attainment also was examined. Findings indicated significant differences between mothers and daughters such that mothers reported later expectations for the timing of behavioral autonomy than did daughters. Follow-up analyses indicated that findings appeared to be driven by maternal nativity, with dyads comprised of Mexico-born mothers reporting the latest age expectations for behavioral autonomy when compared with dyads comprised of U.S.-born mothers. Findings underscore the need to examine normative development among Latino adolescents and their families with a specific focus on how sociocultural characteristics can contribute to within-family differences. PMID:22093152

  16. Does cyclic stress and accelerated ageing influence the wear behavior of highly crosslinked polyethylene?

    PubMed

    Affatato, Saverio; De Mattia, Jonathan Salvatore; Bracco, Pierangiola; Pavoni, Eleonora; Taddei, Paola

    2016-06-01

    First-generation (irradiated and remelted or annealed) and second-generation (irradiated and vitamin E blended or doped) highly crosslinked polyethylenes were introduced in the last decade to solve the problems of wear and osteolysis. In this study, the influence of the Vitamin-E addition on crosslinked polyethylene (XLPE_VE) was evaluated by comparing the in vitro wear behavior of crosslinked polyethylene (XLPE) versus Vitamin-E blended polyethylene XLPE and conventional ultra-high molecular weight polyethylene (STD_PE) acetabular cups, after accelerated ageing according to ASTM F2003-02 (70.0±0.1°C, pure oxygen at 5bar for 14 days). The test was performed using a hip joint simulator run for two millions cycles, under bovine calf serum as lubricant. Mass loss was found to decrease along the series XLPE_VE>STD_PE>XLPE, although no statistically significant differences were found between the mass losses of the three sets of cups. Micro-Raman spectroscopy was used to investigate at a molecular level the morphology changes induced by wear. The spectroscopic analyses showed that the accelerated ageing determined different wear mechanisms and molecular rearrangements during testing with regards to the changes in both the chain orientation and the distribution of the all-trans sequences within the orthorhombic, amorphous and third phases. The results of the present study showed that the addition of vitamin E was not effective to improve the gravimetric wear of PE after accelerated ageing. However, from a molecular point of view, the XLPE_VE acetabular cups tested after accelerated ageing appeared definitely less damaged than the STD_PE ones and comparable to XLPE samples. PMID:26970299

  17. Use of Mental Health Services by Children Ages Six to 11 With Emotional or Behavioral Difficulties

    PubMed Central

    Simon, Alan E.; Pastor, Patricia N.; Reuben, Cynthia A.; Huang, Larke N.; Goldstrom, Ingrid D.

    2015-01-01

    Objective The authors reported use of mental health services among children in the United States between ages six and 11 who were described by their parents as having emotional or behavioral difficulties (EBDs). Methods Using data from the 2010–2012 National Health Interview Survey, the authors estimated the national percentage of children ages six to 11 with serious or minor EBDs (N=2,500) who received treatment for their difficulties, including only mental health services other than medication (psychosocial services), only medication, both psychosocial services and medication, and neither type of service. They calculated the percentage of children who received school-based and non–school-based psychosocial services in 2011–2012 and who had unmet need for psychosocial services in 2010–2012. Results In 2010–2012, 5.8% of U.S. children ages six to 11 had serious EBDs and 17.3% had minor EBDs. Among children with EBDs, 17.8% were receiving both medication and psychosocial services, 28.8% psychosocial services only, 6.8% medication only, and 46.6% neither medication nor psychosocial services. Among children with EBDs in 2011–2012, 18.6% received school-based psychosocial services only, 11.4% non–school-based psychosocial services only, and 17.3% both school- and non–school-based psychosocial services. In 2010–2012, 8.2% of children with EBDs had unmet need for psychosocial services. Conclusions School-age children with EBDs received a range of mental health services, but nearly half received neither medication nor psychosocial services. School-based providers played a role in delivering psychosocial services, but parents reported an unmet need for psychosocial services among some children. PMID:25975889

  18. Pulsed laser surface hardening of ferrous alloys.

    SciTech Connect

    Xu, Z.; Reed, C. B.; Leong, K. H.; Hunter, B. V.

    1999-09-30

    A high power pulsed Nd:YAG laser and special optics were used to produce surface hardening on 1045 steel and gray cast iron by varying the process parameters. Unlike CO{sub 2} lasers, where absorptive coatings are required, the higher absorptivity of ferrous alloys at the Nd:YAG laser wavelength eliminates the necessity of applying a coating before processing. Metallurgical analysis of the treated tracks showed that very fine and hard martensitic microstructure (1045 steel) or inhomogeneous martensite (gray cast iron) were obtained without surface melting, giving maximum hardness of HRC 61 and HRC 40 for 1045 steel and gray cast iron respectively. The corresponding maximum case depths for both alloys at the above hardness are 0.6 mm. Gray cast iron was more difficult to harden without surface melting because of its lower melting temperature and a significantly longer time-at-temperature required to diffuse carbon atoms from the graphite flakes into the austenite matrix during laser heating. The thermal distortion was characterized in term of flatness changes after surface hardening.

  19. Strain Hardening in Bidisperse Polymer Glasses

    NASA Astrophysics Data System (ADS)

    Robbins, Mark O.; Hoy, Robert S.

    2009-03-01

    The connections between glassy and rubbery strain hardening have been a matter of great controversy in recent years. Recent experiments and our earlier simulations have suggested that the hardening modulus GR is proportional to the entanglement density in glasses, as it is to the crosslink density in rubbers. In this work we present more extensive studies of strain hardening in bidisperse glasses and its relation to microscopic conformational changes. The mixtures contain chains of very different lengths but equivalent chemistry. GR does not scale simply with the entanglement density. Instead it obeys a simple mixing rule, with GR equal to the volume fraction weighted average of the moduli of the two pure components. As in recent studies of monodisperse systems (R. S. Hoy and M. O. Robbins, Phys. Rev. Lett. 99, 117801 (2007)), the stress is directly correlated to the degree of chain orientation. Chains of a given length undergo almost the same degree of alignment in pure systems and mixtures, explaining why the simple mixing rule applies. The connection to recent analytic theories by K. Chen and K. S. Schweizer (PRL, in press) will be discussed.

  20. Intelligent systems for induction hardening processes

    SciTech Connect

    Kelley, J.B.; Adkins, D.R.; Robino, C.V.

    1994-12-31

    Induction hardening is widely used to provide enhanced strength, wear resistance, and toughness in components made from medium and high carbon steels. Current limitations of the process include the lack of closed-loop process control, previously unidentified process and material variations which cause continual adjustment of the process parameters, coil and process development by trial and error, and an instability to monitor coil condition. Improvement of the induction hardening process is limited by an inadequate understanding of process fundamentals and material/process interactions. A multidisciplinary team from Sandia National Laboratories and Delphi Saginaw Steering Systems is investigating the induction hardening process under a Cooperative Research and Development Agreement (CRADA). The application of intelligent control algorithms has led to the development of a closed-loop process controller for the combination of one material, one geometry, single frequency, single shot, process that controls to {plus_minus} 0.1mm. This controller will be demonstrated on the production floor this year. Our approach and the opportunities for expanding the usefulness of this technology will be described.

  1. Work hardening: occupational therapy in industrial rehabilitation.

    PubMed

    Matheson, L N; Ogden, L D; Violette, K; Schultz, K

    1985-05-01

    Work hardening, presented in this paper as a "new" service for the industrially injured, is actually well grounded in the traditional models and practices of occupational therapy. From the profession's early roots in industrial therapy to the development of a variety of programs for the industrially injured through the 1950s and 1960s, the historical and philosophical bases of occupational therapy support the use of work as an evaluative and therapeutic medium. What is actually new is the adoption of terminology, technology, and a program format that fits in with the needs of consumers in the 1980s. Recent developments that created the need for the specialized services that occupational therapists are uniquely qualified to provide include growth of private sector vocational rehabilitation, changes in workers' compensation laws, and increasing costs of vocational rehabilitation. This paper describes work hardening in its present form. A case example is given that demonstrates how work hardening can be a cost-effective and time-saving bridge which spans the gap between curative medicine and the return to work. PMID:4014411

  2. Assessment of Cheating Behavior in Young School-Age Children: Distinguishing Normative Behaviors from Risk Markers of Externalizing Psychopathology

    ERIC Educational Resources Information Center

    Callender, Kevin A.; Olson, Sheryl L.; Kerr, David C. R.; Sameroff, Arnold J.

    2010-01-01

    The central goal of this longitudinal study was to develop a laboratory-based index of children's covert cheating behavior that distinguished normative rule violations from those that signal risk for antisocial behavior. Participants (N = 215 children) were drawn from a community population and oversampled for externalizing behavior problems…

  3. Changes in the deformational behavior of human hip cartilage with age.

    PubMed

    Armstrong, C G; Bahrani, A S; Gardner, D L

    1980-08-01

    The deformation occurring in the articular cartilage covering the human femoral head has been measured both when the femoral head is loaded in its natural acetabulum and when the cartilage is loaded with a small indentor. The results indicate that the material response is substantially different in these two situations. In the intact joint the cartilage deformation is substantially greater in older joints, but the response of cartilage to loading with an indentor does not change significantly with age. Theoretical elastic models of the cartilage behavior in these two situations were analyzed. For old cartilage which is idealized as an elastic material the increased deformation which is observed in the intact joint can be attributed to changes in Poisson's ratio, though in the real material increased fluid flux under load is the more probable cause.

  4. Behavioral and electrophysiological changes induced by acetyl-L-carnitine in aged freely-moving rats.

    PubMed

    Marini, G; Calvani, M; Ceccarelli, P; Mancia, M

    2006-02-01

    In chronically-implanted, drug-free, behaving aged Fischer rats, intracerebroventricularly (i.c.v.) and intraperitoneally (i.p.) acetyl-L-carnitine (ALCAR) injections powerfully enhanced motor behavior and head movements aimed at attention and exploratory activity. This effect was dose-dependent and associated with the abolition or substantial reduction of the incidence and duration of the spontaneous EEG generalized hypersynchronous patterns termed High Voltage Spindle (HVS), with an increase in EEG monitored theta activity. The results suggest that ALCAR may stimulate the motivational system and disrupt the hypersynchronous processes by inhibiting the GABAergic thalamic reticular neurons and/or activating the brain stem cholinergic reticular system (pedunculo pontine tegmental, PPT and laterodorsal tegmental, LDT nuclei). PMID:16425616

  5. Cellular prion protein ablation impairs behavior as a function of age.

    PubMed

    Coitinho, Adriana S; Roesler, Rafael; Martins, Vilma R; Brentani, Ricardo R; Izquierdo, Ivan

    2003-07-18

    Cellular prion protein (PrPc) has been associated with some physiological functions in recent reports. Here we investigate behavioral parameters in 3- and 9-month-old mice lacking PrPc protein (Prnp0/0) and in rats after intrahippocampal administration of affinity purified anti-PrPc IgG (0.09 microg/side). No differences were observed between 3-month-old animals. However, 9-month-old Prnp0/0 mice and rats infused with anti-PrPc antibody showed a clear impairment of short- and long-term memory retention of a step-down inhibitory avoidance task. A decreased locomotor activity during exploration of an open field was also observed. These results suggest that systems involved in memory formation become more susceptible to mechanisms that require PrPc between the ages of 3 and 9 months in both mice and rats.

  6. Effects of velvet antler polypeptide on sexual behavior and testosterone synthesis in aging male mice

    PubMed Central

    Zang, Zhi-Jun; Tang, Hong-Feng; Tuo, Ying; Xing, Wei-Jie; Ji, Su-Yun; Gao, Yong; Deng, Chun-Hua

    2016-01-01

    Twenty-four-month-old male C57BL/6 mice with low serum testosterone levels were used as a late-onset hypogonadism (LOH) animal model for examining the effects of velvet antler polypeptide (VAP) on sexual function and testosterone synthesis. These mice received VAP for 5 consecutive weeks by daily gavage at doses of 100, 200, or 300 mg kg−1 body weight per day (n = 10 mice per dose). Control animals (n = 10) received the same weight-based volume of vehicle. Sexual behavior and testosterone levels in serum and interstitial tissue of testis were measured after the last administration of VAP. Furthermore, to investigate the mechanisms of how VAP affects sexual behavior and testosterone synthesis in vivo, the expression of steroidogenic acute regulatory protein (StAR), cytochrome P450 cholesterol side-chain cleavage enzyme (P450scc), and 3β-hydroxysteroid dehydrogenase (3β-HSD) in Leydig cells was also measured by immunofluorescence staining and quantitative real-time PCR. As a result, VAP produced a significant improvement in the sexual function of these aging male mice. Serum testosterone level and intratesticular testosterone (ITT) concentration also increased in the VAP-treated groups. The expression of StAR, P450scc, and 3β-HSD was also found to be enhanced in the VAP-treated groups compared with the control group. Our results suggested that VAP was effective in improving sexual function in aging male mice. The effect of velvet antler on sexual function was due to the increased expression of several rate-limiting enzymes of testosterone synthesis (StAR, P450scc, and 3β-HSD) and the following promotion of testosterone synthesis in vivo. PMID:26608944

  7. Reduced neural specificity in middle-aged HIV+ women in the absence of behavioral deficits.

    PubMed

    Liu, Chenglong; Wang, Cuiwei; Leclair, Matthew; Young, Mary; Jiang, Xiong

    2015-01-01

    In the post combination antiretroviral therapy (cART) era, the prevalence of mild forms of HIV-associated neurocognitive disorders (HAND) in individuals with HIV-infection remains high. There is a pressing need to find biomarkers that can aid clinical assessment of HAND, especially in those with mild or no neurocognitive symptoms. Here we hypothesized that a reduction in neural specificity, or the specificity of neuronal tuning, could serve as a potential biomarker of asymptomatic HAND. To directly test this hypothesis, we applied two advanced fMRI techniques to examine the difference in neural specificity between middle-aged HIV+ women and age-matched negative controls, with a focus on the fusiform face area (FFA), a critical region in face processing. Face discrimination performance was assessed outside of the scanner. While the behavioral performance of face discrimination was comparable between the two groups, a reduced neural specificity in the FFA of HIV-positive women was revealed by a novel fMRI analysis technique, local regional heterogeneity analysis, or Hcorr , as well as an established technique, fMRI-rapid adaptation. In contrast, conventional fMRI techniques were insensitive to these early changes. These results suggest that, prior to the onset of detectable behavioral deficits, significant neuronal dysfunctions are already present in HIV+ individuals, and these early neuronal dysfunctions can be detected and assessed via neural specificity, which, in combining with the novel Hcorr technique, has a strong potential to serve as a biomarker of asymptomatic HAND and other neurodegenerative diseases. PMID:26288750

  8. Physical activity, sedentary behaviors and dietary habits among Saudi adolescents relative to age, gender and region

    PubMed Central

    2011-01-01

    Background Few lifestyle factors have been simultaneously studied and reported for Saudi adolescents. Therefore, the purpose of the present study was to report on the prevalence of physical activity, sedentary behaviors and dietary habits among Saudi adolescents and to examine the interrelationships among these factors using representative samples drawn from three major cities in Saudi Arabia. Methods This school-based cross-sectional study was conducted during the years 2009-2010 in three cities: Al-Khobar, Jeddah and Riyadh. The participants were 2908 secondary-school males (1401) and females (1507) aged 14-19 years, randomly selected using a multistage stratified sampling technique. Measurements included weight, height, sedentary behaviors (TV viewing, playing video games and computer use), physical activity using a validated questionnaire and dietary habits. Results A very high proportion (84% for males and 91.2% for females) of Saudi adolescents spent more than 2 hours on screen time daily and almost half of the males and three-quarters of the females did not meet daily physical activity guidelines. The majority of adolescents did not have a daily intake of breakfast, fruit, vegetables and milk. Females were significantly (p < 0.05) more sedentary, much less physically active, especially with vigorous physical activity, and there were fewer days per week when they consumed breakfast, fruit, milk and diary products, sugar-sweetened drinks, fast foods and energy drinks than did males. However, the females' intake of French fries and potato chips, cakes and donuts, and candy and chocolate was significantly (p < 0.05) higher than the males'. Screen time was significantly (p < 0.05) correlated inversely with the intake of breakfast, vegetables and fruit. Physical activity had a significant (p < 0.05) positive relationship with fruit and vegetable intake but not with sedentary behaviors. Conclusions The high prevalence of sedentary behaviors, physical inactivity and

  9. Empirical beam hardening correction (EBHC) for CT

    SciTech Connect

    Kyriakou, Yiannis; Meyer, Esther; Prell, Daniel; Kachelriess, Marc

    2010-10-15

    Purpose: Due to x-ray beam polychromaticity and scattered radiation, attenuation measurements tend to be underestimated. Cupping and beam hardening artifacts become apparent in the reconstructed CT images. If only one material such as water, for example, is present, these artifacts can be reduced by precorrecting the rawdata. Higher order beam hardening artifacts, as they result when a mixture of materials such as water and bone, or water and bone and iodine is present, require an iterative beam hardening correction where the image is segmented into different materials and those are forward projected to obtain new rawdata. Typically, the forward projection must correctly model the beam polychromaticity and account for all physical effects, including the energy dependence of the assumed materials in the patient, the detector response, and others. We propose a new algorithm that does not require any knowledge about spectra or attenuation coefficients and that does not need to be calibrated. The proposed method corrects beam hardening in single energy CT data. Methods: The only a priori knowledge entering EBHC is the segmentation of the object into different materials. Materials other than water are segmented from the original image, e.g., by using simple thresholding. Then, a (monochromatic) forward projection of these other materials is performed. The measured rawdata and the forward projected material-specific rawdata are monomially combined (e.g., multiplied or squared) and reconstructed to yield a set of correction volumes. These are then linearly combined and added to the original volume. The combination weights are determined to maximize the flatness of the new and corrected volume. EBHC is evaluated using data acquired with a modern cone-beam dual-source spiral CT scanner (Somatom Definition Flash, Siemens Healthcare, Forchheim, Germany), with a modern dual-source micro-CT scanner (TomoScope Synergy Twin, CT Imaging GmbH, Erlangen, Germany), and with a modern

  10. Measurement of irradiation effects in precipitate hardened aluminum using nonlinear ultrasonic principles (in-situ)

    SciTech Connect

    Reinhardt, B. T.; Parks, D. A.; Tittmann, B. R.

    2012-05-17

    Currently nuclear power plants are reaching the end of their initial design life. Yet, in order to meet the energy demands, twenty year extensions have been granted to many nuclear reactor facilities. These extensions will be ending by the year 2035, leaving a large gap in the available energy supply. In order to extend the life of these facilities it will imperative to develop techniques capable detecting damage in the aging nuclear facilities. However, the high temperature and high neutron flux environment limits the materials available for use in the nuclear reactor. Because of this limitation little NDE based inspection has been implemented in high radiation environments. Yet recent developments in the understanding of Aluminum Nitride (AlN) piezoelectric sensors high temperature and radiation dependent behavior have opened the door for in-situ experimentation. An experiment was designed to monitor the propagation of an ultrasonic wave in a precipitate hardened aluminum specimen while being subjected to radiation at the Pennsylvania State Universities Breazeale Reactor. Measurements of harmonic generation were made up to 1.85x10{sup 18} fluence with significant spectral difference between the pre-irradiated state and the post irradiated state. The connection between micro-structural material changes and harmonic measurements are addressed.

  11. Noise exposure at young age impairs the auditory object exploration behavior of rats in adulthood.

    PubMed

    Zhang, Jiping; Chen, Liang; Gao, Fei; Pu, Qing; Sun, Xinde

    2008-09-01

    Environment noise is ubiquitous in our daily life. The aim of the present study was to determine the effect of postnatal exposure to moderate-level noise on the auditory object exploration behavior of adult rats by comparing the ability of three groups of rats to locate a sound source in a water maze. Two groups of rats, either in the critical period of hearing development or in adulthood, were exposed to 80 dB SPL interrupted white noise for 8 h per day for two weeks. The control group of rats was not exposed to the noise. The ability of the rats to locate a hidden platform that was situated near a sound source in a water maze was tested starting on postnatal day 77. A continuous improvement in the performance of control rats and rats exposed to noise in adulthood was observed during training, whereas rats exposed to noise at a young age exhibited a significantly worse performance. These findings indicated that long-term exposure of young rats to moderate-level noise caused significant impairment of their auditory object exploration behavior compared to exposure of adult animals to the same moderate-level noise.

  12. Sex, age and hunger regulate behavioral prioritization through dynamic modulation of chemoreceptor expression

    PubMed Central

    Ryan, Deborah A.; Miller, Renee M.; Lee, KyungHwa; Neal, Scott; Fagan, Kelli A.; Sengupta, Piali; Portman, Douglas S.

    2014-01-01

    Background Adaptive behavioral prioritization requires flexible outputs from fixed neural circuits. In C. elegans, the prioritization of feeding vs. mate-searching depends on biological sex (males will abandon food to search for mates, while hermaphrodites will not) as well as developmental stage and feeding status. Previously, we found that males are less attracted than hermaphrodites to the food-associated odorant diacetyl, suggesting that sensory modulation may contribute to behavioral prioritization. Results We find that somatic sex acts cell-autonomously to reconfigure the olfactory circuit by regulating a key chemoreceptor, odr-10, in the AWA neurons. Moreover, we find that odr-10 has a significant role in food detection, the regulation of which contributes to sex differences in behavioral prioritization. Overexpression of odr-10 increases male food attraction and decreases off-food exploration; conversely, odr-10 loss impairs food taxis in both sexes. In larvae, both sexes prioritize feeding over exploration; correspondingly, the sexes have equal odr-10 expression and food attraction. Food deprivation, which transiently favors feeding over exploration in adult males, increases male food attraction by activating odr-10 expression. Furthermore, the weak expression of odr-10 in well-fed adult males has important adaptive value, allowing males to efficiently locate mates in a patchy food environment. Conclusions We find that modulated expression of a single chemoreceptor plays a key role in naturally occurring variation in the prioritization of feeding and exploration. The convergence of three independent regulatory inputs—somatic sex, age, and feeding status—on chemoreceptor expression highlights sensory function as a key source of plasticity in neural circuits. PMID:25438941

  13. Fish oil supplementation during lactation: effects on cognition and behavior at 7 years of age.

    PubMed

    Cheatham, Carol L; Nerhammer, Anne Sofie; Asserhøj, Marie; Michaelsen, Kim F; Lauritzen, Lotte

    2011-07-01

    Early accumulation of n-3 long-chain PUFA (LCPUFA) in the brain may contribute to differences in later cognitive abilities. In this study, our objective was to examine whether fish oil (FO) supplementation during lactation affects processing speed, working memory, inhibitory control, and socioemotional development at 7 years. Danish mothers (n = 122) were randomized to FO [1.5 g/d n-3 LCPUFA] or olive oil (OO) supplementation during the first 4 months of lactation. The trial also included a high-fish intake (HFI) reference group (n = 53). Ninety-eight children were followed-up with an assessment of processing speed, an age-appropriate Stroop task, and the Strength and Difficulties Questionnaire at 7 year. A group effect of the intervention (FO vs. OO) was found in prosocial behavior scores; this negative effect was carried by the boys. Exploratory analyses including all participants revealed the speed of processing scores were predicted by maternal n-3 LCPUFA intake during the intervention period (negative relation) and maternal education (positive relation). Stroop scores indicative of working memory and inhibitory control were predicted by infant erythrocyte DHA status at 4 months of age (negative relation). Early fish oil supplementation may have a negative effect on later cognitive abilities. Speed of processing and inhibitory control/working memory are differentially affected, with speed of processing showing effects of fish oil intake as a whole, whereas inhibitory control/working memory was related more specifically to DHA status.

  14. Maternal Caffeine Intake During Pregnancy and Child Cognition and Behavior at 4 and 7 Years of Age.

    PubMed

    Klebanoff, Mark A; Keim, Sarah A

    2015-12-15

    Although caffeine is commonly consumed during pregnancy, there are few reports on the association of in utero caffeine exposure with offspring cognition or behavior during childhood. We evaluated the association of maternal serum paraxanthine, caffeine's primary metabolite, at <20 and ≥26 weeks' gestation with the child's intelligence quotient (IQ) and problem behaviors at ages 4 and 7 years among 2,197 mother-child pairs. The mothers were controls from a case-control study of caffeine metabolites and spontaneous abortion that was nested within the Collaborative Perinatal Project (multiple US sites, 1959-1974). Associations of paraxanthine (adjusted for maternal age, race, education, smoking, prepregnancy weight, gestational age at blood draw, and child sex) with mean IQ were assessed by linear regression and associations with problem behaviors by logistic regression. Paraxanthine concentration at ≥26 weeks' gestation manifested an inverted-J-shaped association with child's IQ at age 7 years, with a peak difference (vs. undetectable) of 0.65 points at 750 µg/L (66th percentile) and a decrement thereafter. Paraxanthine at <20 weeks was linearly associated with internalizing behavior at age 4 years (for a 500-µg/L increase, odds ratio = 1.3, 95% confidence interval: 1.1, 1.5). None of the remaining 12 associations approached statistical significance. We conclude that over a range of values applicable to most pregnant women, there was no meaningful association of serum paraxanthine level with childhood IQ or problem behaviors.

  15. Learning ability in aged beagle dogs is preserved by behavioral enrichment and dietary fortification: a two-year longitudinal study.

    PubMed

    Milgram, N W; Head, E; Zicker, S C; Ikeda-Douglas, C J; Murphey, H; Muggenburg, B; Siwak, C; Tapp, D; Cotman, C W

    2005-01-01

    The effectiveness of two interventions, dietary fortification with antioxidants and a program of behavioral enrichment, was assessed in a longitudinal study of cognitive aging in beagle dogs. A baseline protocol of cognitive testing was used to select four cognitively equivalent groups: control food-control experience (C-C), control food-enriched experience (C-E), antioxidant fortified food-control experience (A-C), and antioxidant fortified food-enriched experience(A-E). We also included two groups of young behaviorally enriched dogs, one receiving the control food and the other the fortified food. Discrimination learning and reversal was assessed after one year of treatment with a size discrimination task, and again after two years with a black/white discrimination task. The four aged groups were comparable at baseline. At one and two years, the aged combined treatment group showed more accurate learning than the other aged groups. Discrimination learning was significantly improved by behavioral enrichment. Reversal learning was improved by both behavioral enrichment and dietary fortification. By contrast, the fortified food had no effect on the young dogs. These results suggest that behavioral enrichment or dietary fortification with antioxidants over a long-duration can slow age-dependent cognitive decline, and that the two treatments together are more effective than either alone in older dogs.

  16. Conditional Survival of All Primary Brain Tumor Patients by Age, Behavior, and Histology

    PubMed Central

    Porter, Kimberly R.; McCarthy, Bridget J.; Berbaum, Michael L.; Davis, Faith G.

    2011-01-01

    Background Survival statistics commonly reflect survival from the time of diagnosis but do not take into account survival already achieved after a diagnosis. The objective of this study was to provide conditional survival estimates for brain tumor patients as a more accurate measure of survival for those who have already survived for a specified amount of time after diagnosis. Methods Data on primary malignant and nonmalignant brain tumor cases diagnosed from 1985–2005 from selected SEER state cancer registries were obtained. Relative survival up to 15 years postdiagnosis and varying relative conditional survival rates were computed using the life-table method. Results The overall 1-year relative survival estimate derived from time of diagnosis was 67.8% compared to the 6-month relative conditional survival rate of 85.7% for 6-month survivors (the probability of surviving to 1 year given survival to 6 months). The 10-year overall relative survival rate was 49.5% from time of diagnosis compared to the 8-year relative conditional survival rate of 79.2% for 2-year survivors. Conditional survival estimates and standard survival estimates varied by histology, behavior, and age at diagnosis. The 5-year relative survival estimate derived from time of diagnosis for glioblastoma was 3.6% compared to the 3-year relative conditional survival rate of 36.4% for 2-year survivors. For most nonmalignant tumors, the difference between relative survival and the corresponding conditional survival estimates were minimal. Older age groups had greater numeric gains in survival but lower conditional survival estimates than other age groups. Similar findings were seen for other conditional survival intervals. Conclusions Conditional survival is a useful disease surveillance measure for clinicians and brain tumor survivors to provide them with better ‘real-time’ estimates and hope. PMID:21677447

  17. The effects of interstitial content and annealing on the flow and fracture behavior on polycrystalline beta-NiAl

    NASA Technical Reports Server (NTRS)

    Weaver, M. L.; Levit, V.; Kaufman, M. J.; Noebe, R. D.

    1994-01-01

    The strain behavior of three polycrystalline NiAl alloys has been investigated at temperatures between 300 and 1200 K. Yield stress plateaus, yield stress transients upon a ten-fold increase in strain rate, work hardening peaks, and dips in the strain rate sensitivity (SRS) have been observed between 700 and 800 K. These observations are indicative of dynamic strain aging (DSA) and are discussed in terms of conventional strain aging theories.

  18. Resting heart rate and the development of antisocial behavior from age 9 to 14: genetic and environmental influences.

    PubMed

    Baker, Laura A; Tuvblad, Catherine; Reynolds, Chandra; Zheng, Mo; Lozano, Dora Isabel; Raine, Adrian

    2009-01-01

    The genetic and environmental basis of a well-replicated association between antisocial behavior (ASB) and resting heart rate was investigated in a longitudinal twin study, based on two measurements between the ages of 9 and 14 years. ASB was defined as a broad continuum of externalizing behavior problems, assessed at each occasion through a composite measure based on parent ratings of trait aggression, delinquent behaviors, and psychopathic traits in their children. Parent ratings of ASB significantly decreased across age from childhood to early adolescence, although latent growth models indicated significant variation and twin similarity in the growth patterns, which were explained almost entirely by genetic influences. Resting heart rate at age 9-10 years old was inversely related to levels of ASB but not change patterns of ASB across age or occasions. Biometrical analyses indicated significant genetic influences on heart rate during childhood, as well as ASB throughout development from age 9 to 14. Both level and slope variation were significantly influenced by genetic factors. Of importance, the low resting heart rate and ASB association was significantly and entirely explained by their genetic covariation, although the heritable component of heart rate explained only a small portion (1-4%) of the substantial genetic variance in ASB. Although the effect size is small, children with low resting heart rate appear to be genetically predisposed toward externalizing behavior problems as early as age 9 years old.

  19. [Factors affecting health behavior of the people aged forties--a test of the health belief model].

    PubMed

    Tohnai, S; Hata, E

    1994-04-01

    The health behavior of 1120 persons, aged in their forties, living in a city, a mountain village and a fishing village were analyzed according to the Health Belief Model. Women practiced more health behaviors than men. People living in the city and mountain village practiced more than people in fishing village. Company employees, farmers and housewives practiced more than self-employeds and fishermen. Education level had no significant influence in the practice of health behavior. As predicted, people who believed in the effectiveness of health behavior practiced more health behaviors. On the other hand, people who perceived barriers to health behavior practiced less. Paradoxically, people who perceived vulnerability to hypertension, cerebrovascular disease or cancer, and the seriousness of these diseases, practiced less health behaviors. Stepwise multiple regression analysis revealed that health beliefs, social supports and information from mass media could account for 33.0% of the Health Behavior Score variation. Perceived barriers to health behavior was the strongest determinant for practice of health behavior. Perceived barriers may account for gender and occupational differences in health behavior.

  20. Walking in School-Aged Children in a Dual-Task Paradigm Is Related to Age But Not to Cognition, Motor Behavior, Injuries, or Psychosocial Functioning

    PubMed Central

    Hagmann-von Arx, Priska; Manicolo, Olivia; Lemola, Sakari; Grob, Alexander

    2016-01-01

    Age-dependent gait characteristics and associations with cognition, motor behavior, injuries, and psychosocial functioning were investigated in 138 typically developing children aged 6.7–13.2 years (M = 10.0 years). Gait velocity, normalized velocity, and variability were measured using the walkway system GAITRite without an additional task (single task) and while performing a motor or cognitive task (dual task). Assessment of children’s cognition included tests for intelligence and executive functions; parents reported on their child’s motor behavior, injuries, and psychosocial functioning. Gait variability (an index of gait regularity) decreased with increasing age in both single- and dual-task walking. Dual-task gait decrements were stronger when children walked in the motor compared to the cognitive dual-task condition and decreased with increasing age in both dual-task conditions. Gait alterations from single- to dual-task conditions were not related to children’s cognition, motor behavior, injuries, or psychosocial functioning. PMID:27014158

  1. Urban and rural Differences in the Prevalence of Gender and Age specific Obesity and related Health Behaviors in Korea

    PubMed Central

    Chung, Sang-Jin; Han, Young Shin; Kang, Seung-ho

    2005-01-01

    The objective of this study was to discuss the residential difference in gender and age specific prevalence of obesity by body mass index (BMI) and obesity related health behaviors in the Republic of Korea. A total of nationally representative 2,583 men and 3,087 women (age: 20-64 yr) was used as subjects from 1998 National Health and Nutrition Survey. All statistics were calculated using SUDAAN to consider a stratified multistage probability sampling design. The prevalence of obesity (BMI≥25) was significantly different by age, gender and residential areas. Although younger men aged 20-49 yr did not show a residential difference in the prevalence of obesity, men aged 50-64 yr showed differences, highest in big cities and lowest in rural areas. However, in women, a higher prevalence was observed in rural areas compared to urban areas in the younger age group (20-49 yr), but not in the older age group. Residential differences of obesity related health behaviors existed mostly in the older population, but not in the younger population. The urban-rural differences demonstrate the various stages of behavioral transition that Korea is currently undergoing. Therefore, different strategies considering those factors are needed to manage obesity problems in Korea. PMID:16224141

  2. Behavioral responses of adult female tobacco hornworms, Manduca sexta, to hostplant volatiles change with age and mating status

    PubMed Central

    Mechaber, W.L.; Capaldo, C.T.; Hildebrand, J.G.

    2002-01-01

    We present evidence for two behaviors influenced by intact, vegetative plant odor — upwind flight and abdomen curling — in female Manduca sexta and demonstrate the influence of the age and mating status of the moths on these behaviors. We compared the behavioral responses of laboratory-reared M. sexta. of discrete ages and physiological states (2,3, and 4 day old for virgin; 2 and 3 day old for mated) as individual moths flew upwind in a flight tunnel to a source of hostplant volatiles. We monitored odor-modulated flight and abdomen curling in the presence of volatiles released by potted hostplants. Mated 3 day old females exhibited the highest incidence of odor-modulated flight and abdomen curling. Similarly, as virgin moths aged, a greater percentage of the individuals displayed odor-modulated flight patterns and abdomen curling. In contrast, younger virgin moths exhibited high levels of abdomen curling only after contact with the plant. PMID:15455039

  3. Crack bridging in fiber reinforced cementitious composites with slip-hardening interfaces

    NASA Astrophysics Data System (ADS)

    Lin, Zhong; Li, Victor C.

    1997-05-01

    A new crack bridging model accounting for slip-hardening interfacial shear stress is derived for randomly oriented discontinuous flexible fibers in cement-based composites, based on a micromechanics analysis of single fiber pull-out. The complete composite bridging stress versus crack opening curve ( σB - δ relation) and associated fracture energy are theoretically determined. A micromechanics-based criterion which governs the existence of post-debonding rising branch of the σB - δ curve is obtained. Implications of the present model on various composite properties, including uniaxial tensile strength, flexural strength, ductility and critical fiber volume fraction for strain-hardening, are discussed together with an example of a 2% polyethylene fiber reinforced cement composite. It is found that the present model can very well describe the slip-hardening behavior during fiber pull-out which originates from fiber surface abrasion at fiber/matrix interface. In addition, the new model predicts accurately the enhanced toughness in terms of both ultimate tensile strain and fracture energy of the composite and resolves the deficiency of constant interface shear stress model in predicting the crack opening and ultimate strain, which are critical for material design of pseudo strain hardening engineered cementitious composites (ECCs).

  4. Constitutive modelling of evolving flow anisotropy including distortional hardening

    SciTech Connect

    Pietryga, Michael P.; Vladimirov, Ivaylo N.; Reese, Stefanie

    2011-05-04

    The paper presents a new constitutive model for anisotropic metal plasticity that takes into account the expansion or contraction (isotropic hardening), translation (kinematic hardening) and change of shape (distortional hardening) of the yield surface. The experimentally observed region of high curvature ('nose') on the yield surface in the loading direction and flattened shape in the reverse loading direction are modelled here by means of the concept of directional distortional hardening. The modelling of directional distortional hardening is accomplished by means of an evolving fourth-order tensor. The applicability of the model is illustrated by fitting experimental subsequent yield surfaces at finite plastic deformation. Comparisons with test data for aluminium low and high work hardening alloys display a good agreement between the simulation results and the experimental data.

  5. Specialized induction machines for deep surface and surface hardening

    SciTech Connect

    Andryushchenko, V.T.

    1988-01-01

    Designs of specialized hardening equipment for electrothermal hardening of parts using induction heating are described. These designs include induction machines for deep surface hardening of truck axle shafts, the outer and inner rings of railroad car axle roller bearings, camshafts, axle parts, and the side members of truck frames. This study and others help develop and transmit the technology for producing and introducing specialized induction machines which are effective in heat treatment of heavily loaded machine parts and consume less amounts of metal.

  6. Adolescent mothers and their children: changes in maternal characteristics and child developmental and behavioral outcome at school age.

    PubMed

    Camp, B W

    1996-06-01

    This study examines stability and change in characteristics of adolescent mothers from their child's infancy to school age, describes cognitive and behavioral characteristics of their children at school age, and reports on the relationship between maternal characteristics and child behavior and development at school age. Cognitive status and childrearing attitudes were assessed in 43 adolescent mothers (mean age 16.3 years) when their children were infants (Time 1) and again when children were school age (Time 2). At school age, mothers also completed the Louisville Behavior Checklist, and children were administered the Slosson Intelligence Test and the Wide Range Achievement Test. Significant correlations were obtained between maternal measures at Time 1 and Time 2, and no significant differences were observed between mean scores at Time 1 and Time 2 on any measures. Children demonstrated average intelligence, but mean achievement was almost 1 SD below average. Significantly more children had high scores than expected on scales for hyperactivity and academic disability. Except for maternal vocabulary, maternal measures obtained at Time 1 were not directly related to children's IQ or behavior problems. Maternal vocabulary and authoritarian and hostile childrearing attitudes assessed at Time 1 contributed independently to prediction of achievement test scores in a positive direction. Mothers' vocabulary at Time 2 and high or increased hostile childrearing attitudes contributed positively to prediction of child IQ. Mothers who still had high scores in authoritarian childrearing attitudes or whose scores increased had children with lower IQs. Changes in attitudes or contemporary measures of attitudes were also related to behavior problems at school age.

  7. Metal Artifact Reduction for Polychromatic X-ray CT Based on a Beam-Hardening Corrector.

    PubMed

    Park, Hyoung Suk; Hwang, Dosik; Seo, Jin Keun

    2016-02-01

    This paper proposes a new method to correct beam hardening artifacts caused by the presence of metal in polychromatic X-ray computed tomography (CT) without degrading the intact anatomical images. Metal artifacts due to beam-hardening, which are a consequence of X-ray beam polychromaticity, are becoming an increasingly important issue affecting CT scanning as medical implants become more common in a generally aging population. The associated higher-order beam-hardening factors can be corrected via analysis of the mismatch between measured sinogram data and the ideal forward projectors in CT reconstruction by considering the known geometry of high-attenuation objects. Without prior knowledge of the spectrum parameters or energy-dependent attenuation coefficients, the proposed correction allows the background CT image (i.e., the image before its corruption by metal artifacts) to be extracted from the uncorrected CT image. Computer simulations and phantom experiments demonstrate the effectiveness of the proposed method to alleviate beam hardening artifacts. PMID:26390451

  8. Metal Artifact Reduction for Polychromatic X-ray CT Based on a Beam-Hardening Corrector.

    PubMed

    Park, Hyoung Suk; Hwang, Dosik; Seo, Jin Keun

    2016-02-01

    This paper proposes a new method to correct beam hardening artifacts caused by the presence of metal in polychromatic X-ray computed tomography (CT) without degrading the intact anatomical images. Metal artifacts due to beam-hardening, which are a consequence of X-ray beam polychromaticity, are becoming an increasingly important issue affecting CT scanning as medical implants become more common in a generally aging population. The associated higher-order beam-hardening factors can be corrected via analysis of the mismatch between measured sinogram data and the ideal forward projectors in CT reconstruction by considering the known geometry of high-attenuation objects. Without prior knowledge of the spectrum parameters or energy-dependent attenuation coefficients, the proposed correction allows the background CT image (i.e., the image before its corruption by metal artifacts) to be extracted from the uncorrected CT image. Computer simulations and phantom experiments demonstrate the effectiveness of the proposed method to alleviate beam hardening artifacts.

  9. The effect of aluminum on the work hardening and wear resistance of hadfield manganese steel

    NASA Astrophysics Data System (ADS)

    Zuidema, B. K.; Subramanyam, D. K.; Leslie, W. C.

    1987-09-01

    A study has been made of the work-hardening and wear resistance of aluminum-modified Hadfield manganese steels ranging in composition from 1.00 to 1.75 Pct carbon and from 0.0 to 4.0 Pct aluminum. Aluminum additions reduced carbon activity and diffusivity in austenites of Hadfield’s composition, increasing the metastable solubility of carbon in Hadfield steel. Aluminum additions inhibited mechanical twinning and, by inference, increased the stacking fault energy of austenite. Increasing carbon in solution in austenite expanded the temperature range over which dynamic strain aging and rapid work hardening occurred. Simultaneous aluminum additions and increased carbon content increased the work-hardening rate and high-stress abrasion resistance of Hadfield steel, but there was an optimum aluminum content beyond which both declined. Maximum work-hardening rate was exhibited by an alloy containing nominally 1.75 Pct C, 13.5 Pct Mn, and 1.3 Pct Al. Improved high-stress abrasion resistance was also found in an alloy containing nominally 1.00 Pct C, 13.5 Pct Mn, and 4.0 Pct Al.

  10. Expecting the Unexpected: Radiation Hardened Software

    NASA Technical Reports Server (NTRS)

    Penix, John; Mehlitz, Peter C.

    2005-01-01

    Radiation induced Single Event Effects (SEEs) are a serious problem for spacecraft flight software, potentially leading to a complete loss of mission. Conventional risk mitigation has been focused on hardware, leading to slow, expensive and outdated on-board computing devices, increased power consumption and launch mass. Our approach is to look at SEEs from a software perspective, and to explicitly design flight software so that it can detect and correct the majority of SEES. Radiation hardened flight software will reduce the significant residual residual risk for critical missions and flight phases, and enable more use of inexpensive and fast COTS hardware.

  11. Constitutive equation for hardened SKD11 steel at high temperature and high strain rate using the SHPB technique

    NASA Astrophysics Data System (ADS)

    Tang, D. W.; Wang, C. Y.; Hu, Y. N.; Song, Y. X.

    2010-03-01

    In this present work, dynamic tests have been performed on hardened SKD11 steel (62 Rockwell C hardness) specimens by means of a high temperature split Hopkinson pressure bar (SHPB) test system. Effects of temperature as well as those of strain and strain rate for the hardened steel are taken into account by using two ellipsoidal radiant heating reflectors with two halogen lamps and magnetic valve. The result obtained at high stain rates were compared with those at low strain rates under the different temperature. It was seen that the flow stress curves are found to include a work hardening region and a work softening region and the mechanical behavior of the hardened steel is highly sensitive to both the strain rate and the temperature. To determine the true flow stress- true strain, temperature relationship, specimens are tested from room temperature to 1073K at a strain rate form 0.01 s-1 to 104 s-1: The parameters for a Johnson-Cook constitutive equation and a modified Johnson-Cook constitutive equation are determined from the test results by fitting the data from both quasi-static compression and high temperature-dynamic compression tests. The modified Johnson-Cook constitutive equation is more suitable for expressing the dynamic behavior of the hardened SKD11 steel above the vicinity of the recrystallization temperature.

  12. Constitutive equation for hardened SKD11 steel at high temperature and high strain rate using the SHPB technique

    NASA Astrophysics Data System (ADS)

    Tang, D. W.; Wang, C. Y.; Hu, Y. N.; Song, Y. X.

    2009-12-01

    In this present work, dynamic tests have been performed on hardened SKD11 steel (62 Rockwell C hardness) specimens by means of a high temperature split Hopkinson pressure bar (SHPB) test system. Effects of temperature as well as those of strain and strain rate for the hardened steel are taken into account by using two ellipsoidal radiant heating reflectors with two halogen lamps and magnetic valve. The result obtained at high stain rates were compared with those at low strain rates under the different temperature. It was seen that the flow stress curves are found to include a work hardening region and a work softening region and the mechanical behavior of the hardened steel is highly sensitive to both the strain rate and the temperature. To determine the true flow stress- true strain, temperature relationship, specimens are tested from room temperature to 1073K at a strain rate form 0.01 s-1 to 104 s-1: The parameters for a Johnson-Cook constitutive equation and a modified Johnson-Cook constitutive equation are determined from the test results by fitting the data from both quasi-static compression and high temperature-dynamic compression tests. The modified Johnson-Cook constitutive equation is more suitable for expressing the dynamic behavior of the hardened SKD11 steel above the vicinity of the recrystallization temperature.

  13. Does age of onset of risk behaviors mediate the relationship between child abuse and neglect and outcomes in middle adulthood?

    PubMed

    Horan, Jacqueline M; Widom, Cathy Spatz

    2015-03-01

    Child maltreatment has been linked with a number of risk behaviors that are associated with long-lasting maladaptive outcomes across multiple domains of functioning. This study examines whether the ages of onset of four risk behaviors-sexual intercourse, alcohol use, drug use, and criminal behavior-mediate the relationship between child maltreatment and outcomes in middle adulthood among a sample of court-documented victims of child abuse/neglect and matched controls (N = 1,196; 51.7% female; 66.2% White, 32.6% Black). Adult outcomes included employment status, welfare receipt, internalizing symptoms of anxiety and depressive symptoms, substance use problems, and criminal arrests. The results indicated gender differences in these relationships. For females, age of onset of sexual intercourse mediated the relationship between child abuse/neglect and both internalizing symptoms and substance use problems in middle adulthood. For males, age at first criminal arrest mediated the relationship between child abuse/neglect and extensive involvement in the justice system in middle adulthood. Age of onset of alcohol use and drug use did not mediate the relationship between child abuse/neglect and middle adult outcomes. This study expands current knowledge by identifying associations between early initiation of risk behavior in one domain and later, continuing problems in different domains. Thus, early initiation of specific risk behaviors may have more wide-ranging negative consequences than are typically considered during intervention or treatment and strategies may need to target multiple domains of functioning.

  14. Bisphenol A Exposure and Behavioral Problems among Inner City Children at 7-9 Years of Age

    PubMed Central

    Roen, Emily L.; Wang, Ya; Calafat, Antonia M.; Wang, Shuang; Margolis, Amy; Herbstman, Julie; Hoepner, Lori A.; Rauh, Virginia; Perera, Frederica P.

    2015-01-01

    Background Bisphenol A (BPA) is a ubiquitous endocrine disrupting compound. Several experimental and epidemiological studies suggest that gestational BPA exposure can lead to neurodevelopmental and behavioral problems in early-life, but results have been inconsistent. We previously reported that prenatal BPA exposure may affect child behavior and differently among boys and girls at ages 3-5 years. Objectives We investigated the association of prenatal and early childhood BPA exposure with behavioral outcomes in 7-9 year old minority children and hypothesized that we would observe the same sex-specific pattern observed at earlier ages. Methods African-American and Dominican women enrolled in an inner-city prospective cohort study and their children were followed from mother’s pregnancy through children’s age 7-9 years. Women during the third trimester of pregnancy and children at ages 3 and 5 years provided spot urine samples. BPA exposure was categorized by tertiles of BPA urinary concentrations. The Child Behavioral Checklist (CBCL) was administered at ages 7 and 9 to assess multiple child behavior domains. Associations between behavior and prenatal (maternal) BPA concentrations and behavior and postnatal (child) BPA concentration were assessed via Poisson regression in models stratified by sex. These models accounted for potential confounders including prenatal or postnatal urinary BPA concentrations, child age at CBCL assessment, ethnicity, gestational age, maternal intelligence, maternal education and demoralization, quality of child’s home environment, prenatal environmental tobacco smoke exposure, and prenatal mono-n-butyl phthalate concentration. Results The direction of the associations differed between boys and girls. Among boys (n=115), high prenatal BPA concentration (upper tertile vs. lower two tertiles) was associated with increased internalizing (β=0.41, p<0.0001) and externalizing composite scores (β=0.40, p<0.0001) and with their

  15. Social network analysis - centrality parameters and individual network positions of agonistic behavior in pigs over three different age levels.

    PubMed

    Büttner, Kathrin; Scheffler, Katharina; Czycholl, Irena; Krieter, Joachim

    2015-01-01

    Knowledge of the network structure of agonistic interactions helps to understand the formation and the development of aggressive behavior. Therefore, video observation data of 149 pigs over three different age levels were investigated for 2 days each directly after mixing (65 groups in the rearing area, 24 groups in the growing stable and 12 groups in the breeding stable). The aim of the study was to use network analysis to investigate the development of individual network positions of specific animals and to determine whether centrality parameters in previous mixing situations have an impact on the future behavior of the animals. The results of the weighted degree centrality indicated that weaned pigs had a higher fighting intensity directly after mixing compared to growing pigs and gilts. Also, the number of different opponents (degree centrality) was higher compared to the older age groups. The betweenness centrality showed relatively small values and no significant differences between the different age levels, whereas the closeness centrality showed high values at all observed age levels. Experiences gained in previous agonistic interactions had an impact on the centrality parameters in subsequent mixing situations. It was shown that the position of individual animals in agonistic interaction networks can be characterized using social network analysis and that changes over different age levels can be detected. Therefore, social network analysis provides insights into the formation and evolution of behavioral patterns which could be of particular interest for the identification of key factors with regard to abnormal behavior (e.g. tail biting). PMID:25932371

  16. Aqueous electrochemistry of precipitation-hardened nickel base alloys

    SciTech Connect

    Hosoya, K.; Ballinger, R.; Prybylowski, J.; Hwang, I.S. )

    1990-11-01

    An investigation has been conducted to explore the importance of local crack tip electrochemical processes in precipitation-hardened Ni-Cr-Fe alloys driven by galvanic couples between grain boundary precipitates and the local matrix. The electrochemical behavior of {gamma}{prime} (Ni{sub 3}(Al,Ti)) has been determined as a function of titanium concentration, temperature, and solution pH. The electrochemical behavior of Ni-Cr-Fe solid solution alloys has been investigated as a function of chromium content for a series of 10 Fe-variable Cr (6--18%)-balance Ni alloys, temperature, and pH. The investigation was conducted in neutral and pH3 solutions over the temperature range 25--300{degree}C. The results of the investigation show that the electrochemical behavior of these systems is a strong function of temperature and composition. This is especially true for the {gamma}{prime} (Ni{sub 3}(Al,Ti)) system where a transition from active/passive behavior to purely active behavior and back again occurs over a narrow temperature range near 100{degree}C. Behavior of this system was also found to be a strong function of titanium concentration. In all cases, the Ni{sub 3}(Al,Ti) phase was active with respect to the matrix. The peak in activity near 100{degree}C correlates well with accelerated crack growth in this temperature range, observed in nickel-base alloy X-750 heat treated to precipitate {gamma}{prime} on the grain boundaries. 20 refs., 23 figs., 3 tabs.

  17. Individual Differences in Exercise Behavior: Stability and Change in Genetic and Environmental Determinants From Age 7 to 18.

    PubMed

    Huppertz, Charlotte; Bartels, Meike; de Zeeuw, Eveline L; van Beijsterveldt, Catharina E M; Hudziak, James J; Willemsen, Gonneke; Boomsma, Dorret I; de Geus, Eco J C

    2016-09-01

    Exercise behavior during leisure time is a major source of health-promoting physical activity and moderately tracks across childhood and adolescence. This study aims to investigate the absolute and relative contribution of genes and the environment to variance in exercise behavior from age 7 to 18, and to elucidate the stability and change of genetic and shared environmental factors that underlie this behavior. The Netherlands Twin Register collected data on exercise behavior in twins aged approximately 7, 10, 12, 14, 16 and 18 years (N = 27,332 twins; 48 % males; 47 % with longitudinal assessments). Three exercise categories (low, middle, high) were analyzed by means of liability threshold models. First, a univariate model was fitted using the largest available cross-sectional dataset with linear and quadratic effects of age as modifiers on the means and variance components. Second, a simplex model was fitted on the longitudinal dataset. Heritability was low in 7-year-olds (14 % in males and 12 % in females), but gradually increased up to age 18 (79 % in males and 49 % in females), whereas the initially substantial relative influence of the shared environment decreased with age (from 80 to 4 % in males and from 80 to 19 % in females). This decrease was due to a large increase in the genetic variance. The longitudinal model showed the genetic effects in males to be largely stable and to accumulate from childhood to late adolescence, whereas in females, they were marked by both transmission and innovation at all ages. The shared environmental effects tended to be less stable in both males and females. In sum, the clear age-moderation of exercise behavior implies that family-based interventions might be useful to increase this behavior in children, whereas individual-based interventions might be better suited for adolescents. We showed that some determinants of individual differences in exercise behavior are stable across childhood and youth, whereas

  18. Technology Developments in Radiation-Hardened Electronics for Space Environments

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Howell, Joe T.

    2008-01-01

    The Radiation Hardened Electronics for Space Environments (RHESE) project consists of a series of tasks designed to develop and mature a broad spectrum of radiation hardened and low temperature electronics technologies. Three approaches are being taken to address radiation hardening: improved material hardness, design techniques to improve radiation tolerance, and software methods to improve radiation tolerance. Within these approaches various technology products are being addressed including Field Programmable Gate Arrays (FPGA), Field Programmable Analog Arrays (FPAA), MEMS, Serial Processors, Reconfigurable Processors, and Parallel Processors. In addition to radiation hardening, low temperature extremes are addressed with a focus on material and design approaches. System level applications for the RHESE technology products are discussed.

  19. Voluntary Wheel Running Does not Affect Lipopolysaccharide-Induced Depressive-Like Behavior in Young Adult and Aged Mice

    PubMed Central

    Martin, Stephen A.; Dantzer, Robert; Kelley, Keith W.; Woods, Jeffrey A.

    2014-01-01

    Peripheral stimulation of the innate immune system with lipopolysaccharide (LPS) causes prolonged depressive-like behavior in aged mice that is dependent on indoleamine 2,3 dioxygenase (IDO) activation. Regular moderate intensity exercise training has been shown to exert neuroprotective effects that might reduce depressive-like behavior in aged mice. The purpose of this study was to test the hypothesis that voluntary wheel running would attenuate LPS-induced depressive-like behavior and brain IDO gene expression in 4-month-old and 22-month-old C57BL/6J mice. Mice were housed with a running wheel (Voluntary Wheel Running, VWR) or no wheel (Standard) for 30 days (young adult mice) or 70 days (aged mice), after which they were intraperitoneally injected with LPS (young adult mice: 0.83 mg/kg; aged mice: 0.33 mg/kg). Young adult VWR mice ran on average 6.9 km/day, while aged VWR mice ran on average 3.4 km/day. Both young adult and aged VWR mice increased their forced exercise tolerance compared to their respective Standard control groups. VWR had no effect on LPS-induced anorexia, weight-loss, increased immobility in the tail suspension test, and decreased sucrose preference in either young adult or aged mice. Four (young adult mice) and twenty-four (aged mice) hours after injection of LPS transcripts for TNF-α, IL-1β, IL-6, and IDO were upregulated in the whole brain independently of VWR. These results indicate that prolonged physical exercise has no effect on the neuroinflammatory response to LPS and its behavioral consequences. PMID:24281669

  20. Oral health promotion in early childhood: age of joining preventive program and behavioral aspects

    PubMed Central

    Lemos, Letícia Vargas Freire Martins; Myaki, Silvio Issáo; Walter, Luiz Reynaldo de Figueiredo; Zuanon, Angela Cristina Cilense

    2014-01-01

    ABSTRACT Objective: To analyze the interference of age in the entrance into a public dental care program for infants as well as family behavioral aspects about tooth decay experience in children 0 to 4 years old. Methods: Cross-sectional study involving 465 children who were divided into 3 groups: infants whose mothers joined the program during pregnancy (n=50); infants enrolled in the program during the first year of life (n=230); and infants enrolled in the program between 13 and 18 months old (n=185). The χ2 and Kruskal-Walis tests (95% confidence interval) were used to assess the relationship among variables. Results: There was an association between the age of entrance in the programs and dental caries (p<0.001). A lower prevalence was seen in infants whose mothers joined the program during pregnancy, and among those infants enrolled in the program during the first year of life. The same low prevalence occurred in relation to mothers' commitment to attend follow-up visits with their infants, cariogenic diet, nighttime oral care, duration of night feeding and parents' educational level (p<0.001). Unfavorable socioeconomic conditions (p>0.05) and daily oral care (p=0.214) were common variables in the groups with 99% of occurrence. Commitment to attend follow-up visits, nighttime oral care and parents' educational level (p>0.05) were considered protective factors for dental caries. Cariogenic diet and night feeding were determinant factors to the appearance of dental caries. Conclusion: To promote children oral health it is essential to enroll children in oral health programs and adopt healthy habits as early as possible, besides the adherence of the child to their parents' advice. PMID:24728238