Motion Parameters (motion + parameter)

Distribution by Scientific Domains


Selected Abstracts


Automatic Conversion of Mesh Animations into Skeleton-based Animations

COMPUTER GRAPHICS FORUM, Issue 2 2008
Edilson De Aguiar
Abstract Recently, it has become increasingly popular to represent animations not by means of a classical skeleton-based model, but in the form of deforming mesh sequences. The reason for this new trend is that novel mesh deformation methods as well as new surface based scene capture techniques offer a great level of flexibility during animation creation. Unfortunately, the resulting scene representation is less compact than skeletal ones and there is not yet a rich toolbox available which enables easy post-processing and modification of mesh animations. To bridge this gap between the mesh-based and the skeletal paradigm, we propose a new method that automatically extracts a plausible kinematic skeleton, skeletal motion parameters, as well as surface skinning weights from arbitrary mesh animations. By this means, deforming mesh sequences can be fully-automatically transformed into fullyrigged virtual subjects. The original input can then be quickly rendered based on the new compact bone and skin representation, and it can be easily modified using the full repertoire of already existing animation tools. [source]


Effect of cumulative seismic damage and corrosion on the life-cycle cost of reinforced concrete bridges

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 7 2009
R. Kumar
Abstract Bridge design should take into account not only safety and functionality, but also the cost effectiveness of investments throughout a bridge life-cycle. This paper presents a probabilistic approach to compute the life-cycle cost (LCC) of corroding reinforced concrete (RC) bridges in earthquake-prone regions. The approach is developed by combining cumulative seismic damage and damage associated with corrosion due to environmental conditions. Cumulative seismic damage is obtained from a low-cycle fatigue analysis. Chloride-induced corrosion of steel reinforcement is computed based on Fick's second law of diffusion. The proposed methodology accounts for the uncertainties in the ground motion parameters, the distance from the source, the seismic demand on the bridge, and the corrosion initiation time. The statistics of the accumulated damage and the cost of repairs throughout the bridge life-cycle are obtained by Monte-Carlo simulation. As an illustration of the proposed approach, the effects of design parameters on the LCC of an example RC bridge are studied. The results are valuable in better estimating the condition of existing bridges and, therefore, can help to schedule inspection and maintenance programs. In addition, by taking into consideration the two deterioration processes over a bridge life-cycle, it is possible to estimate the optimal design parameters by minimizing, for example, the expected cost throughout the life of the structure. A comparison between the effects of the two deterioration processes shows that, in seismic regions, the cumulative seismic damage affects the reliability of bridges over time more than the corrosion even for corrosive environments. Copyright © 2008 John Wiley & Sons, Ltd. [source]


A new approach of selecting real input ground motions for seismic design: The most unfavourable real seismic design ground motions

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 8 2007
Chang-Hai Zhai
Abstract This paper presents a new way of selecting real input ground motions for seismic design and analysis of structures based on a comprehensive method for estimating the damage potential of ground motions, which takes into consideration of various ground motion parameters and structural seismic damage criteria in terms of strength, deformation, hysteretic energy and dual damage of Park & Ang damage index. The proposed comprehensive method fully involves the effects of the intensity, frequency content and duration of ground motions and the dynamic characteristics of structures. Then, the concept of the most unfavourable real seismic design ground motion is introduced. Based on the concept, the most unfavourable real seismic design ground motions for rock, stiff soil, medium soil and soft soil site conditions are selected in terms of three typical period ranges of structures. The selected real strong motion records are suitable for seismic analysis of important structures whose failure or collapse will be avoided at a higher level of confidence during the strong earthquake, as they can cause the greatest damage to structures and thereby result in the highest damage potential from an extended real ground motion database for a given site. In addition, this paper also presents the real input design ground motions with medium damage potential, which can be used for the seismic analysis of structures located at the area with low and moderate seismicity. The most unfavourable real seismic design ground motions are verified by analysing the seismic response of structures. It is concluded that the most unfavourable real seismic design ground motion approach can select the real ground motions that can result in the highest damage potential for a given structure and site condition, and the real ground motions can be mainly used for structures whose failure or collapse will be avoided at a higher level of confidence during the strong earthquake. Copyright © 2007 John Wiley & Sons, Ltd. [source]


Direct monitoring of coronary artery motion with cardiac fat navigator echoes

MAGNETIC RESONANCE IN MEDICINE, Issue 2 2003
Thanh D. Nguyen
Abstract Navigator echoes (NAVs) provide an effective means of monitoring physiological motion in magnetic resonance imaging (MRI). Motion artifacts can be suppressed by adjusting the data acquisition accordingly. The standard pencil-beam NAV has been used to detect diaphragm motion; however, it does not monitor cardiac motion effectively. Here we report a navigator approach that directly measures coronary artery motion by exciting the surrounding epicardial fat and sampling the signal with a k -space trajectory sensitized to various motion parameters. The present preliminary human study demonstrates that superior-inferior (SI) respiratory motion of the coronary arteries detected by the cardiac fat NAV highly correlates with SI diaphragmatic motion detected by the pencil-beam NAV. In addition, the cardiac fat navigator gating is slightly more effective than the diaphragmatic navigator gating in suppressing motion artifacts in free-breathing 3D coronary MR angiography (MRA). Magn Reson Med 50:235,241, 2003. © 2003 Wiley-Liss, Inc. [source]


Decreased protein tyrosine phosphorylation and membrane fluidity in spermatozoa from infertile men with varicocele

MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 12 2006
M.G. Buffone
Abstract Varicocele is a prevalent pathology among infertile men. The mechanisms linking this condition to infertility, however, are poorly understood. Our previous work showed a relationship between sperm functional quality and the ability of spermatozoa to respond to capacitating conditions with increased membrane fluidity and protein tyrosine phosphorylation. Given the reported association between varicocele, oxidative stress, and sperm dysfunction, we hypothesized that spermatozoa from infertile patients with varicocele might have a combined defect at the level of membrane fluidity and protein tyrosine phosphorylation. Semen samples from infertile patients with and without grade II/III left varicocele were evaluated for motion parameters (computer-assisted semen analysis [CASA]), hyperactivation (CASA), incidence and intensity of protein tyrosine phosphorylation (phosphotyrosine immunofluorescence and western blotting), and membrane fluidity (Laurdan fluorometry), before and after a capacitating incubation (6 hr at 37°C in Ham's F10/BSA, 5% CO2). Spermatozoa from varicocele samples presented a decreased response to the capacitating challenge, showing significantly lower motility, hyperactivation, incidence and intensity of tyrosine phosphorylation, and membrane fluidity. The findings reported in this article indicate that the sperm dysfunction associated to infertile varicocele coexists with decreased sperm plasma membrane fluidity and tyrosine phosphorylation. These deficiencies represent potential new pathophysiological mechanisms underlying varicocele-related infertility. Mol. Reprod. Dev. 73: 1591,1599, 2006. © 2006 Wiley-Liss, Inc. [source]


Superoxide dismutase content and fatty acid composition in subsets of human spermatozoa from normozoospermic, asthenozoospermic, and polyzoospermic semen samples

MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 4 2003
J. Calamera
Abstract Human ejaculated sperm comprised discrete subsets of spermatozoa, with different degrees of maturation. These subpopulations can be isolated through density gradient centrifugation. Sperm from the lowest density layer show the highest content of docosahexaenoic acid and sterols, and produce the highest levels of reactive oxygen species. The main objective of this study was to determine the superoxide dismutase (SOD) content and fatty acid composition of subsets of spermatozoa isolated from normozoospermic, asthenozoospermic, and polyzoospermic semen samples. Four sperm fractions (1,4) were obtained using ISolate gradient centrifugation. Morphology, motion parameters, SOD content, and fatty acid composition were assessed in the original samples and their fractions. Overall, sperm from normozoospermic samples had higher SOD content than those of asthenozoospermic or polyzoospermic samples. Once fractionated in subsets, the sperm SOD content decreased significantly (P,<,0.0001) from fraction 1 (top) to 4 (bottom) in all three groups of samples. Fatty acid content as well as the oxidation coefficient followed the same pattern, decreasing from fraction 1 to 4 (F1,F4). Normo- and polyzoospermic samples showed similar amounts of fatty acids, while asthenozoospermic samples mostly revealed increased levels. Normozoospermic samples displayed the lowest unsaturated fatty acid (UFA)/SOD ratio. Spermatozoa from astheno- and polyzoospermic samples, two common seminal pathologies, showed higher UFA and lower SOD content than normal sperm, therefore exhibiting a higher susceptibility to peroxidative damage. F4 from all groups, containing the most mature spermatozoa, displayed the lowest polyunsaturated fatty acid and SOD content of all subsets, suggesting that excessive SOD activity as well as abundant peroxidative targets may both be deleterious to sperm function. Mol. Reprod. Dev. 66: 422,430, 2003. © 2003 Wiley-Liss, Inc. [source]


Effects of varicocele upon the expression of apoptosis-related proteins

ANDROLOGIA, Issue 4 2010
F.-W. Chang
Summary Varicocele-associated apoptosis has been recognised as a cause of male infertility. Thus, we assessed the expression of somatic apoptosis-related proteins (the typical protein-dependent apoptosis markers) in ejaculated sperm plasma from both patients with varicocele and normal donors. We evaluated the relationships between certain apoptosis-related proteins and normal semen quality. Semen samples were obtained from 25 patients with varicocele and from 10 normal fertile controls. These samples were compared using computer-assisted semen analysis for motion parameters and manual analysis for morphology, and were also assayed for apoptosis-related protein activation including caspase-3, poly-ACP-ribose polymerase (PARP), the Bcl-2 family (Bcl-2, Bak) and p53 by means of immunoblot analysis. PARP, Bak and p53 were expressed substantially more in the sperm cells of the varicocele group when compared with the normal group (P < 0.05). The expression of caspase-3 and Bcl-2 did not appear to differ between these two study groups. An increased expression of PARP, Bak and p53 for varicocele-afflicted individuals indicated an increased participation by these agents in the regulating of apoptosis in the ejaculated semen from patients with varicocele, suggesting that certain protein-development apoptotic mechanisms might originate in the cytoplasmic droplet or within mitochondria of spermatocytes and then might function within the nucleus of the cell. [source]