1,721,040 research outputs found
A biomechanical analysis of plantar fasciitis using digital fluoroscopy
No full textPlantar fasciitis is the most common disorder of the foot and is characterised by pain involving the inferomedial aspect of the heel that is exacerbated by activity after periods of non-weightbearing. Despite an abundance of anecdotal evidence indicating that aberrant function of the foot is an aetiological factor in the development of plantar heel pain, there is little scientific evidence linking abnormal arch mechanics with plantar fasciitis. The primary purpose of this thesis was to investigate the biomechanics of plantar fasciitis by evaluating the sagittal plane kinematics and kinetics of the medial longitudinal arch during gait. Specifically, a low-dose motion X-ray technique, known as digital fluoroscopy, was used to evaluate the sagittal plane kinematics of the arch and a capacitance-based pressure plate was used to determine regional vertical ground reaction forces acting on the sole of the foot during gait.\ud
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Since digital fluoroscopy has not been widely used in gait analysis, the methodological phase of this study concentrated on identifying and quantifying the inherent limitations and potential errors in employing fluoroscopy as a gait analysis technique. In particular, the methodological phase evaluated the potential impact of the physical restrictions of the equipment on gait and the acquisition of gait data, as well as the magnitude of the distortion errors inherent in fluoroscopic images of the medial longitudinal arch. The findings indicate that digital fluoroscopy may be effectively used as a two-dimensional motion analysis technique for the evaluation of movement of the medial longitudinal arch during walking. The methodological studies demonstrate that the structural limitations of modem fluoroscopic systems are unlikely to substantially influence the acquisition of gait data. However, out-ofplane motion of osseous segments of the foot and the temporal response of the imaging system represent the major shortcomings of employing fluoroscopy as a gait analysis tool. Tests conducted on foot models and in vivo indicated that the application of published dist01iion correction procedures provided a method that is highly repeatable, with fluoroscopic image enors constituting less than 5 percent of the movement range.\ud
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In the experimental phase of this thesis, a digital fluoroscope and a pressure platform were used to evaluate the kinematics and kinetics of the medial longitudinal arch in people with and without plantar fasciitis. While pressure analysis demonstrated that patients with plantar fasciitis make gait adjustments that reduce the level of force beneath the rearfoot and forefoot of the symptomatic foot, fluoroscopy indicated that neither the dynamic shape nor the motion of the medial longitudinal arch differed between subjects with and without heel pain. Consequently, abnonnal arch shape and motion are not associated with the progression of plantar fasciitis. The peak arch angle was, however, positively correlated to the increased fascial thickness that was prototypic of plantar fasciitis. Thus, arch mechanics may play an important secondary role in plantar fasciitis by modifying the severity of heel pain, once present. In addition, increased loading and flexion of the digits was observed in patients with heel pain, suggesting that digital function plays an important, and previously unidentified, protective role in plantar fasciitis by bracing the medial longitudinal arch and thereby reducing the loading in the plantar fascia. The findings also suggest that plantar fasciitis may represent a bilateral process and raise questions regarding the rationale behind current treatments aimed at modifying the mechanics of the medial longitudinal arch in heel pain
Ground Reaction Forces at Discrete Sites of the Foot Derived from Pressure Plate Measurements
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A Comparison of Footprint Indexes Calculated From Ink and Electronic Footprints
No full textPressure platforms offer the potential to measure and record electronic footprints rapidly; however, the accuracy of geometric indexes derived from these prints has not been investigated. A comparison of conventional ink footprints with simultaneously acquired electronic prints revealed significant differences in several geometric indexes. The contact area was consistently underestimated by the electronic prints and resulted in a significant change in the arch index. The long plantar angle was poorly correlated between techniques. This study demonstrated that electronic footprints, derived from a pressure platform, are not representative of the equivalent ink footprints and, consequently, should not be interpreted with reference to literature on conventional footprints. (J Am Podiatr Med Assoc 91(4): 203-209, 2001
A Comparison of Two Analytical Techniques for Detecting Differences in Regional Vertical Impulses Due to Plantar Fasciitis
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Hypermetabolism in B–lymphocytes from malignant hyperthermia susceptible individuals
No full textMalignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle metabolism which is characterized by generalized muscle rigidity, increased body temperature, rhabdomyolysis, and severe metabolic acidosis. The underlying mechanism of MH involves excessive Ca2+ release in myotubes via the ryanodine receptor type 1 (RyR1). As RyR1 is also expressed in B–lymphocytes, this study investigated whether cellular metabolism of native B–lymphocytes was also altered in MH susceptible (MHS) individuals. A potent activator of RyR1, 4–chloro–m–cresol (4-CmC) was used to challenge native B-lymphocytes in a real–time, metabolic assay based on a pH–sensitive silicon biosensor chip. At the cellular level, a dose–dependent, phasic acidification occurred with 4–CmC. The acidification rate, an indicator of metabolic activation, was significantly higher in B–lymphocytes from MHS patients and required 3 to 5 fold lower concentrations of 4–CmC to evoke similar acidification rates to MHN. Native B–lymphocytes from MHS individuals are more sensitive to 4–CmC than those from MHN, reflecting a greater Ca2+ turnover. The acidification response, however, was less pronounced than in muscle cells, presumably reflecting the lower expression of RyR1 in B–lymphocytes
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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