6,400 research outputs found

    On Bend-Minimized Orthogonal Drawings of Planar 3-Graphs

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    An orthogonal drawing of a graph is a planar drawing where each edge is drawn as a sequence of horizontal and vertical line segments. Finding a bend-minimized orthogonal drawing of a planar graph of maximum degree 4 is NP-hard. The problem becomes tractable for planar graphs of maximum degree 3, and the fastest known algorithm takes O(n^5 log n) time. Whether a faster algorithm exists has been a long-standing open problem in graph drawing. In this paper we present an algorithm that takes only O~(n^{17/7}) time, which is a significant improvement over the previous state of the art

    RELATIONSHIP BETWEEN THE KINEMATICS OF THE TRUNK AND LOWER EXTREMITIES AND BALL VELOCITY DURING THE OVERHAND THROW IN MALE CANOE POLO PLAYERS

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    The purpose of this study was to examine the relationship between the motion of the trunk and lower extremities and ball velocity during the overhand throw in canoe polo. Fifteen male national canoe polo team players participated in this study. The overhand throwing motion was captured using a three dimensional motion analysis system. Kinematic and temporal parameters in the trunk and lower extremities were measured and analyzed. Results indicated that five variables were associated with variations in ball velocity. Specifically, as ball velocity increased, canoe polo players showed an increased maximal angular velocity in trunk-tilt sideways, upper torso rotation, and right knee flexion. In addition, the right knee flexion range of motion and time to maximum right knee flexion angular velocity increased as ball velocity increased

    A Retrospective Cohort Study Comparing Stroke Recurrence Rate in Ischemic Stroke Patients With and Without Acupuncture Treatment.

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    Little was known about the effects of acupuncture on stroke recurrence. The aim of this study is to investigate whether ischemic stroke patients receiving acupuncture treatment have a decreased risk of stroke recurrence. A retrospective cohort study of 30,058 newly diagnosed cases of ischemic stroke in 2000 to 2004 was conducted based on the claims of Taiwan National Health Insurance Research Database. The use of acupuncture treatment and stroke recurrence were identified during the follow-up period from 2000 to 2009. This study compared the risk of stroke recurrence between ischemic stroke cohorts with and without acupuncture treatment by calculating adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) of acupuncture associated with stroke recurrence in the Cox proportional hazard model. The stroke recurrence rate per 1000 person-years decreased from 71.4 without to 69.9 with acupuncture treatment (P < 0.001). Acupuncture treatment was associated with reduced risk of stroke recurrence (HR 0.88; 95% CI 0.84-0.91). The acupuncture effect was noted in patients with or without medical treatment for stroke prevention but its impact decreased with aging of stroke patients. Compared with stroke patients without acupuncture treatment and medication therapy, the hazard ratios of stroke recurrence for those had medication therapy only, acupuncture only, and both were 0.42 (95% CI 0.38-0.46), 0.50 (95% CI 0.43-0.57), and 0.39 (95% CI 0.35-0.43), respectively. This study raises the possibility that acupuncture might be effective in lowering stroke recurrence rate even in those on medications for stroke prevention. Results suggest the need of prospective sham-controlled and randomized trials to establish the efficacy of acupuncture in preventing stroke

    KINEMATICS ANALYSIS OF THE UPPER EXTREMITY DURING THE TWOHANDED BACKHAND DRIVE VOLLEY FOR FEMALE TENNIS PLAYERS

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    The purpose of this study was to discuss the motion characteristics of the arms in the two-handed backhand drive volley. Five elite female tennis players participated in this study, their two-handed backhand drive volley strokes were analysed, and all participants are right handed. Motion Analysis System with 10 Eagle Digital inferred high speed cameras at 200Hz were used for this study. The results show a similar elbow and wrist speed strategy in x-axis between two-handed ground stroke and drive volley, our study also found that the rear arm dominates the stroke and mainly provide the topspin that is required for the skill of the drive volley. In order to create better stroke efficiency, the right elbow reached peak velocity first, followed by the right wrist before racket impact with the ball

    Hydrogel Models with Stiffness Gradients for Interrogating Pancreatic Cancer Cell Fate

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    Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer and has seen only modest improvements in patient survival rate over the past few decades. PDAC is highly aggressive and resistant to chemotherapy, owing to the presence of a dense and hypovascularized fibrotic tissue, which is composed of stromal cells and extracellular matrices. Increase deposition and crosslinking of matrices by stromal cells lead to a heterogeneous microenvironment that aids in PDAC development. In the past decade, various hydrogel-based, in vitro tumor models have been developed to mimic and recapitulate aspects of the tumor microenvironment in PDAC. Advances in hydrogel chemistry and engineering should provide a venue for discovering new insights regarding how matrix properties govern PDAC cell growth, migration, invasion, and drug resistance. These engineered hydrogels are ideal for understanding how variation in matrix properties contributes to the progressiveness of cancer cells, including durotaxis, the directional migration of cells in response to a stiffness gradient. This review surveys the various hydrogel-based, in vitro tumor models and the methods to generate gradient stiffness for studying migration and other cancer cell fate processes in PDAC
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