1,721,276 research outputs found
Monitoring human activities that might cause work-related musculoskeletal disorders by means of inertial and magnetic sensors
No full textActivity recognition based on new wearable technologies is considered a key research challenge in the field of applied ergonomics. Deterioration of workers' physical health and loss of workdays impact not only on their wellbeing and quality of life, but also on European countries economy. Musculoskeletal disorders are injuries or pain affecting muscles, joints and tendons. If these disorders are work related are described as Work related Musculoskeletal Disorders (WMSDs). Inertial and magnetic sensor units (IMUs) might open new perspectives in detection and objective measure of WMSDs because they allow to collect data on work activities under free conditions and over extended periods of time. The evolution of technologies has observed not only improvement in measurement accuracy and precision, but also a reduction in intrusiveness and an enhanced fit of the measure technologies
Influence of body segment parameters and modeling assumptions on the estimate of center of mass trajectory
No full textThis study sought to determine the effect of inaccuracies in body segment parameters and modeling assumptions on the estimate of antero-posterior center of mass (COM) trajectory. Four different methods, one based on segmental kinematics, and three methods based on kinetic recordings were compared via simulation. Kinematic patterns (quiet stance, ankle-related sway, hip-ankle-related sway, sit-up and sit-up-sit-down) were tested with a 2D four-link model of the body and the ground reaction force vector was obtained by inverse dynamics. Errors in the estimation of body segment parameters were simulated by applying a ±10% variation to one or more parameters at a time. These errors propagated differently to the COM estimated location between methods, between parameters within the same method, and between tasks. The kinematics-based method was the most sensitive to body segment parameters, with special regards to segment lengths and head-arms-trunk parameters. Root mean square error between estimated and simulated COM location reached 19mm in balance-related tasks and 38.3mm in sit-up-sit-down. The kinetics-based methods were largely less sensitive to inaccuracies in body segment parameters. In particular, the technique proposed by Zatsiorsky and King (J. Biomech. 31 (1998) 161), was completely insensitive to segment parameters. On the other hand the kinetics-based methods showed an intrinsic estimation error, due to the underlying model assumptions. The methods based on the double integration of horizontal force had better outcomes with tasks challenging such assumptions, with a maximal error in COM location of 15mm in the sit-up-sit-down. The method proposed by Shimba (J. Biomech. 17 (1984) 53) showed the best trade-off between sensitivity to body segment parameters and estimation performances given the ideal test conditions. © 2003 Elsevier Ltd. All rights reserved
Physiological responses to pain in cancer patients: A systematic review
Full text linkBackground and objective: Pain is one of the most debilitating symptoms in persons with cancer. Still, its assessment is often neglected both by patients and healthcare professionals. There is increasing interest in conducting pain assessment and monitoring via physiological signals that promise to overcome the limitations of state-of-the-art pain assessment tools. This systematic review aims to evaluate existing experimental studies to identify the most promising methods and results for objectively quantifying cancer patients’ pain experience. Methods: Four electronic databases (Pubmed, Compendex, Scopus, Web of Science) were systematically searched for articles published up to October 2020. Results: Fourteen studies (528 participants) were included in the review. The selected studies analyzed seven physiological signals. Blood pressure and ECG were the most used signals. Sixteen physiological parameters showed significant changes in association with pain. The studies were fairly consistent in stating that heart rate, the low-frequency to high-frequency component ratio (LF/HF), and systolic blood pressure positively correlate with the pain. Conclusions: Current evidence supports the hypothesis that physiological signals can help objectively quantify, at least in part, cancer patients’ pain experience. While there is much more to be done to obtain a reliable pain assessment method, this review takes an essential first step by highlighting issues that should be taken into account in future research: use of a wearable device for pervasive recording in a real-world context, implementation of a big-data approach possibly supported by AI, including multiple stratification factors (e.g., cancer site and stage, source of pain, demographic and psychosocial data), and better-defined recording procedures. Improved methods and algorithms could then become valuable add-ons in taking charge of cancer patients
A comprehensive simulator of the human respiratory system: Validation with experimental and simulated data
No full textA comprehensive model of oxygen (O2) and carbon dioxide (CO2) exchange, transport, and storage in the adult human is presented, and its ability to provide realistic responses under different physiological conditions is evaluated. The model comprises three compartments (i.e., lung, body tissue, and brain tissue) and incorporates a controller that adjusts alveolar ventilation and cardiac output dynamically integrating stimuli coming from peripheral and central chemoreceptors, A new realistic CO2 dissociation curve based on a two-buffer model of acid-base chemical regulation is included. In addition, the model explicitly considers relevant physiological factors such as buffer base, the nonlinear interaction between the O2 and CO2 chemoreceptor responses, pulmonary shunt, dead space, variable time delays, and Bohr and Haldane effects. Model simulations provide results consistent with both dynamic and steady-state responses measured in subjects undergoing inhalation of high CO2 (hypercapnia) or low O2 (hypoxia) and subsequent recovery. An analysis of the results indicates that the proposed model fits the experimental data of ventilation and gas partial pressures as some meaningful simulators now available and in a very large range of gas intake fractions. Moreover, it also provides values of blood concentrations of CO2, HCO3-, and hydrogen ions in good agreement with more complex simulators characterized by an implicit formulation of the CO2 dissociation curve. In the experimental conditions analyzed, the model seems to represent a single theoretical framework able to appropriately describe the different phenomena involved in the control of respiration
Effects of deep brain stimulation and levodopa on postural sway in Parkinson's disease
No full textObjective: To quantify postural sway in subjects with Parkinson's disease and elderly controls, and determine the effects of Parkinson's disease, deep brain stimulation, levodopa, and their interactions on postural control during quiet stance. Methods: Centre of foot pressure (CoP) displacement under each foot was measured during three 60 s trials of quiet stance with eyes open in 11 controls and six patients with Parkinson's disease. Subjects with Parkinson's disease were tested in four treatment conditions: off both deep brain stimulation and levodopa (off condition); on deep brain stimulation; on levodopa; and on both deep brain stimulation and levodopa. The variables extracted from CoP included: root mean square distance (rms), mean velocity, 95% power frequency (f95%), area of the 95% confidence ellipse (ellipse area), direction of its major axis (mdir), and postural asymmetry between the feet. Results: rms and area of postural sway were larger than normal in subjects with Parkinson's disease in the off condition, increased further with levodopa, and significantly decreased with deep brain stimulation. Mean velocity and f95% were also larger than normal but were restored to normal by all treatments, especially by deep brain stimulation. The combined effect of deep brain stimulation and levodopa resulted in a postural sway that was an average of the effect of each treatment individually. Levodopa increased sway more in the mediolateral than in the anterior-posterior direction. Subjects with Parkinson's disease had asymmetrical mean velocity and f95% between the feet, and this asymmetry increased with levodopa but decreased with deep brain stimulation. The f95% of the CoP correlated with tremor, posture, and gait subcomponents of the unified Parkinson's disease rating scale. Conclusions: Subjects with Parkinson's disease have abnormal postural sway in stance. Treatment with levodopa increases postural sway abnormalities, whereas treatment with deep brain stimulation improves postural sway. Quantitative evaluation of static posturography may be a useful adjunct to clinical measures in patients with Parkinson's disease
Stabilometric parameters are affected by anthropometry and foot placement
No full textObjective. To recognize and quantify the influence of biomechanical factors, namely anthropometry and foot placement, on the more common measures of stabilometric performance, including new-generation stochastic parameters. Design. Fifty normal-bodied young adults were selected in order to cover a sufficiently wide range of anthropometric properties. They were allowed to choose their preferred side-by-side foot position and their quiet stance was recorded with eyes open and closed by a force platform. Background. Biomechanical factors are known to influence postural stability but their impact on stabilometric parameters has not been extensively explored yet. Methods. Principal component analysis was used for feature selection among several biomechanical factors. A collection of 55 stabilometric parameters from the literature was estimated from the center-of-pressure time series. Linear relations between stabilometric parameters and selected biomechanical factors were investigated by robust regression techniques. Results. The feature selection process returned height, weight, maximum foot width, base-of-support area, and foot opening angle as the relevant biomechanical variables. Only eleven out of the 55 stabilometric parameters were completely immune from a linear dependence on these variables. The remaining parameters showed a moderate to high dependence that was strengthened upon eye closure. For these parameters, a normalization procedure was proposed, to remove what can well be considered, in clinical investigations, a spurious source of between-subject variability. Conclusion. Care should be taken when quantifying postural sway through stabilometric parameters. It is suggested as a good practice to include some anthropometric measurements in the experimental protocol, and to standardize or trace foot position
TATOO - Touchscreen Assessment TOOL for assessing the older adult's functions while operating the touch screen
No full textIn today's highly technology-oriented world, touch screen technology (TST) is rapidly becoming essential for participation in social, personal, and occupational activities1, and is becoming more prevalent due to its convenience, design flexibility, and the ease involved in manipulating touch interfaces2. When an older person uses a TST, ideally, this should meet his/her needs perfectly and instantly which make them confident and happy to be using such a product. However, the reality of such an experience for many of them lead to frustration and eventually to under usage of the technology. One of the reasons is poor device selection. Purpose Assistive technology professionals are aware of the lack of dependable assessment tools to determine clients' behavior and needs in AT selection in general and in TST in particular3. The aim of this study was to describe the processes of reaching consensus regarding the assessment of the user's skills required to operate various touch screen devices for developing the tool named TATOO. Method A six-step procedure was used to collect and validate the required skills by a multidisciplinary team of 52 experts. Content validity was calculated to determine the agreement levels between the experts. Results & Discussion The final version of the tool includes 15 domains and 50 skills/measurements. The result of Cronbach's a test for the final assessment questionnaire was 0.94, which indicates a high degree of internal consistency4. Each of the skills appearing in the final questionnaire was illustrated in a flowchart in preparation for developing TATOO as a software application. A prototype for the main skills was developed in a comprehensive and objective manner, with a summary report presented through a graphic display. Quality assurance process was performed and all of TATOO's components were tested by the technical team and ten occupational therapists. The development of TATOO may contribute to bridging the existing gap in the assessment tools for determining older adults' needs to operate TST and to provide tailor-made recommendations. This may help AT experts to get new information and measurements about TST
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
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
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