998 resultados para habit strength


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The aim of this paper is to focus discussion on some philosophical issues that informs discussion of the stabilising dimension of higher education as a mediating institution. Backgrounded habits provide the deep context for developing moral practice and other regarding sentiment in higher education. Understanding higher educational institutions as mediating institutions, as forms of associational life which inculcate habit and the development of mores is an important corrective to the discourse of marketization and neo-liberal reform which otherwise crowds out consideration of the role higher educational institutions play in cultural stabilization and social cohesion. This argument we intend to make in this paper is that the stabilizing and associational function of higher educational institutions is critically important to developing habits and mores which are the key support for a society that can still retain a sense of concern and regard for others. 

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Evidence suggests that the cross-transfer of strength following unilateral training may be modulated by increased corticospinal excitability of the ipsilateral primary motor cortex, due to cross-activation. Anodal-tDCS (a-tDCS) has been shown to acutely increase corticospinal excitability and motor performance, which may enhance this process. Therefore, we sought to examine changes in neural activation and strength of the untrained limb following the application of a-tDCS during a single unilateral strength training session. Ten participants underwent three conditions in a randomized, double-blinded crossover design: (1) strength training + a-tDCS, (2) strength training + sham-tDCS and (3) a-tDCS alone. a-tDCS was applied for 20 min at 2 mA over the right motor cortex. Unilateral strength training of the right wrist involved 4 × 6 wrist extensions at 70 % of maximum. Outcome measures included maximal voluntary strength, corticospinal excitability, short-interval intracortical inhibition, and cross-activation. We observed a significant increase in strength of the untrained wrist (5.27 %), a decrease in short-interval intracortical inhibition (−13.49 %), and an increase in cross-activation (15.71 %) when strength training was performed with a-tDCS, but not following strength training with sham-tDCS, or tDCS alone. Corticospinal excitability of the untrained wrist increased significantly following both strength training with a-tDCS (17.29 %), and a-tDCS alone (15.15 %), but not following strength training with sham-tDCS. These findings suggest that a single session of a-tDCS combined with unilateral strength training of the right limb increases maximal strength and cross-activation to the contralateral untrained limb.

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Physical inactivity, inadequate dietary protein, and low-grade systemic inflammation contribute to age-related muscle loss, impaired function, and disability.

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To assess the efficacy of applying anodal transcranial direct current stimulation (a-tDCS) to the ipsilateral motor cortex (iM1) during unilateral strength training to enhance the neurophysiological and functional effects of cross-education.

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Objectives: To investigate whether neuromuscular performance predicts lower limb bone strength in different lower limb sites in postmenopausal women with mild knee osteoarthritis (OA). Methods: Neuromuscular performance of 139 volunteer women aged 50-68 with mild knee OA was measured using maximal counter movement jump test, isometric knee flexion and extension force and figure-of-eight-running test. Femoral neck section modulus (Z, mm3) was determined by data obtained from dualenergy X-ray absorptiometry. Data obtained using peripheral quantitative computed tomography was used to asses distal tibia compressive (BSId, g2/cm4) and tibial mid-shaft bending (SSImaxmid, mm3) strength indices. Results: After adjustment for height, weight and age, counter movement jump peak power production was the strongest independent predictor for Z (β=0.44; p<0.001) and for BSId (β=0.32; p=0.003). This was also true in concentric net impulse for Z (β=0.37; p=0.001) and for BSId (β=0.40; p<0.001). Additionally, knee extension force (β=0.30; p<0.001) and figure-of-eight-running test (β= -0.32; p<0.001) were among strongest independent predictors for BSId after adjustments. For SSImaxmid, concentric net impulse (β=0.33; p=0.002) remained as the strongest independent predictor after adjustments. Conclusions: Neuromuscular performance in postmenopausal women with mild knee OA predicted lower limb bone strength in every measured skeletal site.

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In this paper we derive conditions under which optimal tax rates for addictive goods exceed tax rates for non-addictive consumption goods within a rational addiction framework where exogenous government spending cannot be financed with lump sum taxes. We reexamine classic results on optimal commodity taxation and find a rich set of new findings. Two dynamic effects exist. First, households anticipating higher future addictive tax rates reduce current addictive consumption, so they will be less addicted when the tax rate increases. Therefore, addictive tax revenue falls prior to the tax increase. Surprisingly, the optimal tax rate on addictive goods is generally decreasing in the strength of tolerance, since strong tolerance strengthens this tax anticipation effect. Second, high current tax rates on addictive goods make households less addicted in the future, affecting all future tax revenues in a way which depends on how elasticities are changing over time. Classic results on uniform commodity taxation emerge as special cases when elasticities are constant and the addiction function is homogeneous of degree one. Finally, we also study features of addictive goods such as complementarity to leisure that, while not directly related to the definition of addiction, are nonetheless properties many addictive goods display.

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We investigated the association between undercarboxylated osteocalcin (ucOC) and lower-limb muscle strength in women over the age of 70years. The study also aims to confirm the association between bone turnover markers and heel ultrasound measures. A post-hoc analysis using data collected as part of a randomized placebo-controlled trial of vitamin D supplementation. An immunoassay was used to quantify total OC (tOC), with hydroxyapatite pre-treatment for ucOC. We determined associations of absolute and relative (ucOC/tOC; ucOC%) measures of ucOC with lower-limb muscle strength, heel ultrasound measures of speed of sound (SOS) and broadband ultrasound attenuation (BUA), bone turnover markers (BTMs; P1NP and CTx) and the acute phase protein alpha-1-antichymotrypsin (α-ACT). ucOC%, but not absolute ucOC concentration, was positively associated with hip flexor, hip abductor and quadriceps muscle strength (all p<0.05). ucOC% was negatively associated with α-ACT (β-coefficient=-0.24, p=0.02). tOC was positively associated with both P1NP and CTx (p<0.001). For each per unit increase in tOC (μg/L) there was a corresponding lower BUA, SOS and SI (β-coefficient = -0.28; -0.23 and -0.23, respectively; all p<0.04). In conclusion, ucOC% is positively associated with muscle strength and negatively associated with α-ACT. These data support a role for ucOC in musculoskeletal interactions in humans. Whilst tOC is associated with bone health, ucOC% and ucOC may also be linked to falls and fracture risk by influencing muscle function.

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Gait speed is a recommended geriatric assessment of physical performance, but may not be regularly examined in clinical settings. We aimed to investigate whether quadriceps strength tests demonstrate similar predictive ability for incident falls as gait speed in older women. We investigated 135 female volunteers aged mean±SD 76.7±5.0 years (range 70-92) at high risk of fracture. Participants completed gait speed assessments using the GAITRite Electronic Walkway System, and quadriceps strength assessments using a hand-held dynamometer (HHD). Participants reported incident falls monthly for 3.7±1.2 years. N=99 (73%) participants fell 355 times during the follow-up period (mean fall rate 83 per 100 person years). We observed a reduced odds ratio for multiple falls (0.83, 95% CI 0.70-0.98) and a reduced hazard ratio for time to first fall (0.90, 95% CI 0.83-0.98), according to quadriceps strength. There was also a significantly shorter time to first fall for those with low quadriceps strength (<7.0 kg; lowest tertile) compared with those with normal quadriceps strength (estimated means [95% CI] 1.54 [1.02, 2.06] vs. 2.23 [1.82, 2.64] years; P=0.019), but not for those with low (<1.0 m/s) vs. normal gait speed (P=0.15). Quadriceps strength is a significant predictor of incident falls over three years amongst community-dwelling older women at high risk of fracture. Quadriceps strength tests may be an acceptable alternative to gait speed for geriatric assessments of falls risk.

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The unloading behavior was compared for three different steel grades: a dual-phase steel, a transformation-induced plasticity steel, and a twinning-induced plasticity steel. Steels that harden by phase transformation or deformation twinning exhibited a smaller component of microplastic strain during unloading and a smaller reduction in the chord modulus compared to the conventional hardening steel. As a result, unloading is closer to pure elastic unloading when the TRIP effect or TWIP effect is active.

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Complex molecules have been successfully grafted onto the surface of unsized carbon fibre, a heterogeneous material which is a challenge to functionalise. The in situ generation of highly reactive phenyldiazo-species from their corresponding anilines was employed to achieve this task. The success of an initial proof-of-concept study (bearing a nitro moiety) supported by X-ray Photoelectron Spectroscopy (XPS) and physical characterisation, led to the design and synthesis of a more complex compound possessing a pendant amine moiety which could theoretically react with an epoxide based resin. After attachment to unsized oxidised fibres, analysis by XPS of the resulting fibres (fluorine used as an XPS tag) indicated a marked difference in functionalisation success which was attributed to steric factors, shown to be critical in influencing the attachment of the phenyldiazo-intermediate to the carbon fibre surface. Analysis of key fibre performance parameters of these fibres showed no change in elastic modulus, strength, surface topography or microscopic roughness when compared to the control unsized oxidised fibres. The functionalised fibres did however show a large increase in coefficient of friction. Single fibre fragmentation tests indicated a marked increase in interfacial shear strength, which was attributed to the pendent amine functionalities interacting with the epoxy resin.

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The multi-phase, metastable, and multi-scale (M3) constitution of a novel transformation-induced plasticity (TRIP) steel (Fe-0.17C-6.5Mn-1.1Al-0.22Mo-0.05Nb, wt pct) was designed through thermodynamic calculations combined with experimental analysis. In this study, Mo and Nb microalloying was used to control the fraction of retained austenite and its mechanical stability during tensile deformation and to improve the yield strength. Thermodynamic calculations were developed to determine the critical annealing temperature, at which a large fraction of retained austenite (~38 pct) would be obtained through the effects of solute enrichment. The experimental observation was in good agreement with the predicted results. According to the critical annealing temperature, such an ultrafine (<200 nm) M3, microstructure with optimum mechanical stability was successfully achieved. The results of this work demonstrated the superior performance with improved yield strength of 1020 to 1140 MPa and excellent ductility (>30 pct), as compared with other TRIP steels. Both angle-selective backscatter and electron backscatter diffraction techniques were employed to interpret the transformation from the deformed martensitic laths to the ultrafine austenite and ferrite duplex structure.

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This study is dedicated to the quantification of latent hardening and its effect on the plasticity of pure hexagonal magnesium. To this end, discrete dislocation dynamics simulations are used to (1) extract latent hardening parameters coupling different slip systems, and to (2) assess the validity of two existing constitutive models linking slip system strength to dislocation densities on all slip systems. As hexagonal materials deform via activation of different slip modes, each with different mobilities and lattice friction stress, the effects of the latter on latent hardening evolution are also investigated. It is found that the multi-slip formulation proposed by Franciosi and Zaoui gives accurate predictions when multiple interactions are involved while the formulation suggested by Lavrentev and Pokhil systematically overestimates the flow stress. Similar to FCC materials, it is also found that collinear interactions potentially contribute the most to latent hardening. Basal/pyramidal c + a interactions are found to be very strong, while interactions involving second-order pyramidal c + a primary dislocations appear to be the weakest ones. Finally, the latent hardening parameters, extracted from the discrete dislocation dynamics simulations, are used in polycrystal simulations and the impact of finely accounting for latent hardening on predictions of the macroscopic anisotropic response is shown to be of significant importance.

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The microstructure of transformation induced plasticity (TRIP) and dual phase (DP) multiphase steels after stamping of an industrial component at different strain levels was investigated using transmission electron microscopy. The TRIP steel microstructure showed a more complex dislocation substructure of ferrite at different strain levels than DP steel. The deformation microstructure of the stamped parts was compared to the deformation microstructure in these complex steels for different "equivalent" tensile strains. It was found that the microstructures are similar only at high levels of strain (>10 pct) for both steels. © 2014 The Minerals, Metals & Materials Society and ASM International.