Mapping of the morphological and the material characteristics on the glenoid and estimation of predominant loading condition on the glenoid through the mapping

The aim of this study was to predict and map the regional distribution of the trabecular architecture and the material properties of the glenoid and to estimate the predominant loading condition on the glenoid through the mapping. The morphological and material characteristics of the glenoid were investigated by analyzing digitized trabecular bone images obtained from twelve cadaver scapula specimens. The morphological and material characteristics computed from the cadaver specimens show that the predominant loading on the glenoid generally occurs during shoulder movement, which produces forces directed toward the posterior aspect of the bare region. This study is innovative in its detailed mapping of the morphological and material characteristics of the glenoid and its pioneering approach used to estimate the loading pattern acting on the glenoid through the mapping. This paper was recommended for publication in revised form by Associate Editor Young Eun Kim Dohyung Lim received B.S. and M.S. degrees in Biomedical Engineering from Inje University, Kimhae, Korea, in 1998 and 2000, respectively. He then went on to receive his Ph.D. degree from School of Biomedical Engineering, Science, & Health Systems, Drexel University, Philadelphia, PA, USA, in 2004. Dr. Lim completed a postdoctoral fellowship in Department of Physical Therapy and Human Movement Science, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA and a Research Professor of Biomedical Engineering, Yonsei University, Wonju, Gangwon, Korea. Dr. Lim is currently a Senior Researcher at the Korea Institute of Industrial Technology in Cheonan, Chungnam, Korea. Han-Sung Kim received B.S. and M.S. degrees in Machine Design and Production Engineering from Hanyang University, Seoul, Korea, in 1989 and 1991, respectively. Dr. Kim received Ph.D. degree in Mechanical Engineering from University of Manchester Institute of Science and Technology, Manchester, UK, in 1999. Dr. Kim is currently an Associated Professor at the Biomedical Engineering at Yonsei University in Wonju, Korea. Jung-Sung Kim received B.S. and M.S. degrees in Biomedical Engineering from Inje University, Kimhae, Korea, in 1996 and 1998, respectively. He is currently in the doctor’s course in Department of Medical Engineering and BK 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea. Rami Seliktar has a BS and MS degree in Mechanical Engineering, from The Technion, IIT, and Ph.D. (BME) from Strathclyde University, Scotland. He has held academic appointments in several institutions worldwide: Strathclyde University (2yrs.); associate professor at the Technion (9yrs.); Texas A&M (on sabbatical leave from the Technion), and twenty seven years as professor of BME and ME at Drexel University in Philadelphia. Concurrently he founded and directed a Biomechanics laboratory at the Loewenstein Rehab. in Israel and consulted to governments, public agencies and industries. Prof. Seliktar has done research on limb prosthetics, human performance, orthopedic and occupational biomechanics, assistive technology for automomobil dynamics. His research has been funded by: The NSF, NIH, the RWJ Foundation, the Easter Seal Foundation, NIDRR, AIduPont, the United Cerebral Palsy and some hospitals. He has published numerous articles in scientific journals, book chapters and conference proceedings. At the present, Rami Seliktar is Professor and Vice Director of the School of Biomedical Engineering, Science and Health Systems of Drexel University. Sung-Jae Lee received B.S. and M.Eng. degrees in Mechanical Engineering from Cornell University, Ithaca, NY, USA, in 1984 and 1985, respectively. He re-ceived Ph.D. degree in Biomedical Engineering from University of Iowa, Iowa City, IA, USA, in 1993 Dr. Lee is currently a Professor at Department of Biomedical Engineering, Inje University, Gimhae, Gyongnam, Korea. He is currently serving as a board member for the Division for Health Care Technology Assessment of International Federation of Medical and Biological Engineering (IFMBE), a executive member of Korean Orthopedic Research Society, director of international relations for the Korean Society for Biomaterials and also for the Korean Society of Biomechanics.     

Cohesive fracture modeling of crack growth in thick-section composites

This paper presents a combined method for modeling the mode-I and II crack growth behavior in thick-section fiber reinforced polymeric composites having a nonlinear material response. The experimental part of this study includes crack growth tests of a thick composite material system manufactured using the pultrusion process. It consists of alternating layers of E-glass unidirectional roving and continuous filament mats in a polymeric matrix. Integrated micromechanical and cohesive finite element (FE) models are used to simulate the crack growth response in eccentrically loaded single-edge-notch, (tension), ESE(T) and notched butterfly specimens. Micromechanical constitutive models for the mat and the roving layers are used to generate the effective nonlinear material behavior from the in situ fiber and matrix responses. The validity of the numerical modeling approach before the onset of crack growth is investigated using an infrared thermal method. Cohesive FE models are calibrated and used to simulate the complete crack growth behavior for different crack configurations. The proposed integrated framework of multi-scale material models with cohesive fracture models is shown to be an effective method for predicting the structural and material responses including failure load and crack growth in thick-section fiber reinforced polymeric composites.     

Functional MRI activity characterization using response time shift estimates from curve evolution

Characterizing the response of the brain to a stimulus based on functional magnetic resonance imaging data is a major challenge due to the fact that the response time delay of the brain may be different from one stimulus phase to the next and from pixel to pixel. To enhance detectability, this work introduces the use of a curve evolution approach that provides separate estimates of the response time shifts at each phase of the stimulus on a pixel-by-pixel basis. The approach relies on a parsimonious but simple model that is nonlinear in the time shifts of the response relative to the stimulus and linear in the gains. To effectively use the response time shift estimates in a subspace detection framework, we implement a robust hypothesis test based on a Laplacian noise model. The algorithm provides a pixel-by-pixel functional characterization of the brain's response. The results based on experimental data show that response time shift estimates, when properly implemented, enhance detectability without sacrificing robustness.     

A Fast Algorithm for k-Nearest Neighbor Problem on a Reconfigurable Mesh Computer

Given a set S of m points stored on a reconfigurable mesh computer of size n×n, one point per processing element (PE). In this paper we present a parallel method for solving the k-Nearest Neighbor problem (k-NN). This method permits each point of S to know its k-NN (0<k<m). The corresponding algorithm requires that each PE must have 2k registers where it stores the (x,y) coordinates of its k-NN in a given order. This algorithm has a complexity of O(logh+k ²) times, where h is a maximal number of points within a row of the mesh. This complexity is reduced to O(k ²) times, using an appropriate procedure which demonstrates the power of the reconfiguration operations carried out by the processors, and the polymorphic properties of the mesh.     

Fracture Toughness Measurement of Glass and Ceramic Materials Using Chevron-Notched Specimens

Fracture toughness of several different materials was measured using chevronnotched short bar and four-point bend specimens For glass-ceramic and ceramic samples both specimens gave valid results. Fracture toughness values measured with bend specimens are 5% to 10% higher compared to those of the short bar. Consistent results for glass could be obtained only with short bar specimens. The notch width of the bend specimen affected the stability of crack growth in glass samples. Fracture toughness values measured in the present study are in good agreement with those of the previous studies.     

Immobilization of trypsin on poly(alginic acid-g-glycidyl methacrylate-co-methyl methacrylate)

A method of enzyme immobilization by graft copolymerization onto alginic acid is reported. Glycidylmethacrylate along with methyl methacrylate was used as a vinylating reagent. The enzyme trypsin has been chosen for our studies. The effects of various parameters such as pH optima, temperature optima, pH stability, thermal stability, storage stability, and re-usability were studied.     

Measuring the vague meanings of probability terms.

Assessed membership functions over the [0,1] probability interval for several vague meanings of probability terms (e.g., doubtful, probable, likely), using a modified pair-comparison procedure in 2 experiments with 20 and 8 graduate business students, respectively. Ss performed 2 tasks in both experiments: They judged (A) to what degree one probability rather than another was better described by a given probability term and (B) to what degree one term rather than another better described a specified probability. Probabilities were displayed as relative areas on spinners. Task A data were analyzed from the perspective of conjoint-measurement theory, and membership function values were obtained for each term according to various scaling models. Findings show that the conjoint-measurement axioms were well satisfied and goodness-of-fit measures for the scaling procedures were high. Individual differences were large but stable, and the derived membership function values satisfactorily predicted the judgments independently obtained in Task B. Results indicated that the scaled values represented the vague meanings of the terms to the individual Ss in the present experimental context. (51 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An optimal boundary fair scheduling algorithm for multiprocessor real-time systems

With the emergence of multicore processors, the research on multiprocessor real-time scheduling has caught more researchers’ attention recently. Although the topic has been studied for decades, it is still an evolving research field with many open problems. In this work, focusing on periodic real-time tasks with quantum-based computation requirements and implicit deadlines, we propose a novel optimal scheduling algorithm, namely boundary fair (Bfair), which can achieve full system utilization as the well-known Pfair scheduling algorithms. However, different from Pfair algorithms that make scheduling decisions and enforce proportional progress (i.e., fairness) for all tasks at each and every time unit, Bfair makes scheduling decisions and enforces fairness to tasks only at tasks’ period boundaries (i.e., deadlines of periodic tasks). The correctness of the Bfair algorithm to meet the deadlines of all tasks’ instances is formally proved and its performance is evaluated through extensive simulations. The results show that, compared to that of Pfair algorithms, Bfair can significantly reduce the number of scheduling points (by up to 94%) and the overhead of Bfair at each scheduling point is comparable to that of the most efficient Pfair algorithm (i.e., PD²). Moreover, by aggregating the time allocation of tasks for the time interval between consecutive period boundaries, the resulting Bfair schedule can dramatically reduce the number of required context switches and task migrations (as much as 82% and 85%, respectively) when compared to those of Pfair schedules, which in turn reduces the run-time overhead of the system.     

A hierarchy of LMI inner approximations of the set of stable polynomials

Exploiting spectral properties of symmetric banded Toeplitz matrices, we describe simple sufficient conditions for the positivity of a trigonometric polynomial formulated as linear matrix inequalities (LMIs) in the coefficients. As an application of these results, we derive a hierarchy of convex LMI inner approximations (affine sections of the cone of positive definite matrices of size m) of the nonconvex set of Schur stable polynomials of given degree n<m. It is shown that when m tends to infinity the hierarchy converges to a lifted LMI approximation (projection of an LMI set defined in a lifted space of dimension quadratic in n) already studied in the technical literature. An application to robust controller design is described.     

Mobility-aware clustering algorithms with interference constraints in wireless mesh networks

One of the major concerns in wireless mesh networks (WMNs) is the radio resource utilization efficiency, which can be enhanced by managing efficiently the mobility of users as well as the interference effect among neighboring links. To achieve this, we propose in this paper the use of clustering and a new interference-aware routing metric, called INX. Specifically, we first propose two mobility-aware clustering algorithms that take into consideration the mobility properties of users in order to improve the WMN performance. Then, we propose the use of INX in the clustering process in order to maximize the total network throughput. We prove through simulations that both clustering schemes can achieve significant gains in terms of radio resource utilization and load balancing, especially when using the INX metric. Hence, and as a main contribution, we show that by taking into account the interference effect between links, we can improve the performance of our clustering algorithms and increase the gain initially observed with the conventional hop-count metric.