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## Thermal stability of the martensitic transformation of Cu-Al-Ni-Mn-Ti

Fernandez, J.; Benedetti, A. V.; Guilemany, J. M.; Zhang, X. M.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 723-725
ENG
Relevância na Pesquisa
36.03%
The development of new shape memory alloys with high martensitic transformation temperature increases the potential for applications. The development and use of these new alloys depends on the stability of the structure during cycling at high temperatures. If it is possible to guarantee that on alloys keeps the structure during cycling, then the alloy can be used because of the shape memory properties. The aim of this work is to obtain a kinetic model of the forward and backward martensitic transformation of two Cu-Al-Ni-Mn-Ti alloys. Differential scanning calorimetry has been performed in order to establish the kinetic stability of the martensite and the beta transformation. (c) 2006 Elsevier B.V. All rights reserved.

## DETERMINATION OF INSTANTANEOUS STABILITY AGAINST BACKWARD BALANCE LOSS: TWO COMPUTATIONAL APPROACHES

Yang, Feng; Passariello, Fausto; Pai, Yi-Chung
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
26.25%
The purposes of this study were (1) to develop two computation methods and (2) to compare their performance (i.e. the accuracy and the time demand) in determining instantaneous stability, i.e., the shortest distance from an instantaneous center of mass (COM) state to all interpolated points on the stability boundary in the COM position-velocity state space. The intuitive numerical method interpolated the stability boundary against backward balance loss based on four sets of discrete boundary values with a spline function and a preset step size (Δx). Then a brute-force search approach was used to determine this shortest distance. The analytical method uses quadratic polynomial functions to represent the boundaries. The stability was then determined by using the Lagrange multiplier method to find the optimum for the analytical expression of the distance from this given COM state to the boundary. Because reducing Δx can supposedly improve the accuracy of spline fitting, we used this approach to establish the benchmark employed to determine the accuracy level of all other computations. Based on the results from a database of 67 sit-to-stand-slip trials and 687 gait-slip trials, we would recommend the numerical method with Δx =0.1 to reach an adequate accuracy level of 10−2. By changing one order of Δx from 0.1 to 0.01...

## Predicted threshold against backward balance loss in gait

Yang, Feng; Anderson, Frank C.; Pai, Yi-Chung
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
26.32%
The purpose of this study was to determine the minimum forward center of mass (COM) velocity required to prevent backward loss of balance in gait as function of the initial COM position. We hypothesized that these threshold values would be different from those previously published for standing because of the postural differences between gait and standing. To investigate this issue, we constructed a seven-link, nine-degree-of-freedom biomechanical model and employed dynamic optimization to estimate these threshold values under two initial postural conditions: (1) the posture at the beginning of swing phase (i.e., at toe-off), and (2) symmetric bipedal standing. In particular, for a range of possible COM positions posterior to the base of support (BOS), simulated annealing was used to search for the minimum velocity that could carry the COM into the BOS and avoid backward loss of balance. We found that the stability boundary against backward balance loss in walking had a similar overall trend as that previously published for standing. In general, the minimal COM velocity necessary to prevent a backward loss of balance in walking was greater than that in symmetric bipedal standing, and the difference could approach 30% or more when the COM started 0.5 and 1.0 foot-lengths behind the BOS. These discrepancies suggest that simpler biomechanical models...

## Stability of Visual Masking Performance in Recent-Onset Schizophrenia: An 18-Month Longitudinal Study

Lee, Junghee; Nuechterlein, Keith H.; Subotnik, Kenneth L.; Sugar, Catherine A.; Ventura, Joseph; Gretchen-Doorly, Denise; Kelly, Kimberly; Green, Michael F.
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
26.18%
Visual masking deficit in schizophrenia has been suggested to be a potential vulnerability marker for schizophrenia. An important characteristic of a vulnerability marker is stability over time, but relatively little is known about the longitudinal course of masking performance of schizophrenia patients. In this study, we examined the stability of visual masking performance in recent-onset schizophrenia patients over an 18-month period. We administered both forward and backward masking trials with multiple stimulus onset asynchronies for four masking conditions at three time points (baseline, 6-month, and 18-month). Recent-onset schizophrenia patients showed stable masking performance for both forward and backward conditions over a period of 18 months. Furthermore, the stable performance was observed across all four masking conditions. The findings of this study provide further support for the view that visual masking deficits reflect a possible vulnerability marker for schizophrenia.

## Steps to Take to Enhance Gait Stability: The Effect of Stride Frequency, Stride Length, and Walking Speed on Local Dynamic Stability and Margins of Stability

Hak, Laura; Houdijk, Han; Beek, Peter J.; van Dieën, Jaap H.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.42%
The purpose of the current study was to investigate whether adaptations of stride length, stride frequency, and walking speed, independently influence local dynamic stability and the size of the medio-lateral and backward margins of stability during walking. Nine healthy subjects walked 25 trials on a treadmill at different combinations of stride frequency, stride length, and consequently at different walking speeds. Visual feedback about the required and the actual combination of stride frequency and stride length was given during the trials. Generalized Estimating Equations were used to investigate the independent contribution of stride length, stride frequency, and walking speed on the measures of gait stability. Increasing stride frequency was found to enhance medio-lateral margins of stability. Backward margins of stability became larger as stride length decreased or walking speed increased. For local dynamic stability no significant effects of stride frequency, stride length or walking speed were found. We conclude that adaptations in stride frequency, stride length and/or walking speed can result in an increase of the medio-lateral and backward margins of stability, while these adaptations do not seem to affect local dynamic stability. Gait training focusing on the observed stepping strategies to enhance margins of stability might be a useful contribution to programs aimed at fall prevention.

## Differences in long-term memory stability and AmCREB level between forward and backward conditioned honeybees (Apis mellifera)

Felsenberg, Johannes; Dyck, Yan; Feige, Janina; Ludwig, Jenny; Plath, Jenny Aino; Froese, Anja; Karrenbrock, Melanie; Nölle, Anna; Heufelder, Karin; Eisenhardt, Dorothea
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.41%
In classical conditioning a predictive relationship between a neutral stimulus (conditioned stimulus; CS) and a meaningful stimulus (unconditioned stimulus; US) is learned when the CS precedes the US. In backward conditioning the sequence of the stimuli is reversed. In this situation animals might learn that the CS signals the end or the absence of the US. In honeybees 30 min and 24 h following backward conditioning a memory for the excitatory and inhibitory properties of the CS could be retrieved, but it remains unclear whether a late long-term memory is formed that can be retrieved 72 h following backward conditioning. Here we examine this question by studying late long-term memory formation in forward and backward conditioning of the proboscis extension response (PER). We report a difference in the stability of memory formed upon forward and backward conditioning with the same number of conditioning trials. We demonstrate a transcription-dependent memory 72 h after forward conditioning but do not observe a 72 h memory after backward conditioning. Moreover we find that protein degradation is differentially involved in memory formation following these two conditioning protocols. We report differences in the level of a transcription factor...

## Measuring the Determinants of Backward Linkages from FDI in Developing Economies : Is it a Matter of Size?

Sanchez-Martin, Miguel Eduardo; De Pinies, Jaime; Antoine, Kassia
Fonte: World Bank Group, Washington, DC Publicador: World Bank Group, Washington, DC
EN_US
Relevância na Pesquisa
36.16%
The main focus of the paper is the measurement of the potential for externalities related to foreign direct investment. A series of novel proxies are drawn from the Enterprise Survey database of the World Bank-IFC and tested against hypotheses considered in the foreign direct investment literature. Using these proxies, an econometric assessment of the determinants of backward linkages in developing economies is presented. The results show that export-oriented foreign direct investment, wholly owned subsidiaries (as opposed to joint ventures), and foreign owned firms relying on foreign technologies are less likely to develop links with domestic companies. In addition, the analysis finds that some sectors (food, wood, auto, and auto-parts) are more prone than others (textiles and electronics) in developing backward linkages. Apart from the type of foreign direct investment and sector-specific characteristics, the size of the host economy matters. Foreign owned subsidiaries in most service oriented Caribbean islands buy a low percentage of inputs from domestic firms. This may be because in small islands there are not enough local suppliers with sufficient quality and capacity to meet the demands of multinationals. However...

## Middle-Income Countries : Development Challenges and Growing Global Role

Fallon, Peter; Hon, Vivian; Qureshi, Zia; Ratha, Dilip
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Policy Research Working Paper; Publications & Research
ENGLISH; EN_US
Relevância na Pesquisa
26.22%