scholarly journals Locomotion Mode Recognition with Inertial Signals for Hip Joint Exoskeleton

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Gang Du ◽  
Jinchen Zeng ◽  
Cheng Gong ◽  
Enhao Zheng
Keyword(s):  
Hip Joint ◽  
Gait Cycle ◽  
Inertial Sensors ◽  
Recognition Accuracy ◽  
Small Sample Size ◽  
Small Sample ◽  
Joint Angles ◽  
Practical Applications ◽  
Mode Recognition ◽  
Locomotion Mode

Recognizing locomotion modes is a crucial step in controlling lower-limb exoskeletons/orthoses. Our study proposed a fuzzy-logic-based locomotion mode/transition recognition approach that uses the onrobot inertial sensors for a hip joint exoskeleton (active pelvic orthosis). The method outputs the recognition decisions at each extreme point of the hip joint angles purely relying on the integrated inertial sensors. Compared with the related studies, our approach enables calibrations and recognition without additional sensors on the feet. We validated the method by measuring four locomotion modes and eight locomotion transitions on three able-bodied subjects wearing an active pelvic orthosis (APO). The average recognition accuracy was 92.46% for intrasubject crossvalidation and 93.16% for intersubject crossvalidation. The average time delay during the transitions was 1897.9 ms (28.95% one gait cycle). The results were at the same level as the related studies. On the other side, the study is limited in the small sample size of the subjects, and the results are preliminary. Future efforts will be paid on more extensive evaluations in practical applications.

scholarly journals Method for instrumentation of orthotic joints for measurement of internal joint loads

2017 ◽  
Vol 3 (1) ◽  
pp. 35-38
Author(s):  
David Hochmann ◽  
Lucien Opitz
Keyword(s):  
Gait Analysis ◽  
Cross Talk ◽  
Inertial Sensors ◽  
Small Sample Size ◽  
Fem Simulation ◽  
Small Sample ◽  
Safety Testing ◽  
Internal Joint ◽  
Custom Made ◽  
Joint Loads

Abstract:Introduction:The lack of knowledge of mechanical loads in orthotic joints can lead to oversized or breaking components. Previous studies suffer from small sample size and technical limitations. The goal of this study was to develop and validate a method that allows the direct measurement of moments in sagittal, frontal and transverse planes in knee and ankle joints of existing custom made orthoses.Methods:We developed a modular measurement system based on standard joint components, which were instrumented with strain gauges. To ensure sufficient signals and reduce cross talk an iterative approach based on FEM simulation was utilized. The system also contains inertial sensors for mobile gait analysis.Results:Instrumented joints show good results regarding linearity, hysteresis and cross talk. First pilot trials with post-polio and ICP patients demonstrated that joint loads depend on several factors and not solely on body weight. If combined with conventional gait analysis, measurement results can characterize the individual muscle situation of the patient.Conclusion:A novel method for obtaining data on loads in orthotic components was developed and validated. It provides the basis to develop safety testing standards and clinical guidelines, as well as allowing individual optimization of orthotic devices.

scholarly journals Concurrent Validity of a Novel Wireless Inertial Measurement System for Assessing Trunk Impairment in People with Stroke

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1699
Author(s):  
Norah Alhwoaimel ◽  
Martin Warner ◽  
Ann-Marie Hughes ◽  
Federico Ferrari ◽  
Jane Burridge ◽  
...  
Keyword(s):  
Concurrent Validity ◽  
Inertial Sensors ◽  
Small Sample Size ◽  
Rank Correlation ◽  
Objective Measure ◽  
Chronic Stroke ◽  
Small Sample ◽  
Post Stroke ◽  
Trunk Movements ◽  
Discriminant Ability

Background: The Trunk Impairment Scale (TIS) is recommended for clinical research use to assess trunk impairment post-stroke. However, it is observer-dependent and neglects the quality of trunk movements. This study proposes an instrumented TIS (iTIS) using the Valedo system, comprising portable inertial sensors, as an objective measure of trunk impairment post-stroke. Objective: This study investigates the concurrent and discriminant ability of the iTIS in chronic stroke participants. Methods: Forty participants (20 with chronic stroke, 20 healthy, age-matched) were assessed using the TIS and iTIS simultaneously. A Spearman rank correlation coefficient was used to examine concurrent validity. A ROC curve was used to determine whether the iTIS could distinguish between stroke participants with and without trunk impairment. Results: A moderate relationship was found between the observed iTIS parameters and the clinical scores, supporting the concurrent validity of the iTIS. The small sample size meant definitive conclusions could not be drawn about the parameter differences between stroke groups (participants scoring zero and one on the clinical TIS) and the parameter cut-off points. Conclusions: The iTIS can detect small changes in trunk ROM that cannot be observed clinically. The iTIS has important implications for objective assessments of trunk impairment in clinical practice.

scholarly journals Examiner reliability and clinical responsiveness of motion palpation to detect biomechanical dysfunction of the the hip joint

2017 ◽  
Author(s):  
◽  
Gina Leigh Bertolotti
Keyword(s):  
Hip Joint ◽  
Diagnostic Tool ◽  
Small Sample Size ◽  
Diagnostic Techniques ◽  
Small Sample ◽  
Hip Pain ◽  
Anatomical Landmarks ◽  
Chi Square ◽  
Left Hand ◽  
Chi Square Test

Background: Hip pain is a common problem. Motion palpation is a manual technique applied by the hands in various degrees of joint motion that specifically evaluates range of motion in relation to specific anatomical landmarks, joint play and end feel. Motion palpation remains one of the most used diagnostic techniques and yet it remains unclear whether or not it is a reliable, sensitive and specific tool; especially in the hip joint. Objectives: This study assessed intra- and inter-examiner reliability and clinical responsiveness of motion palpation when it is used as a diagnostic tool in patients with non-specific unilateral anterior hip pain and unilateral asymptomatic hip joints. Methods: Ten participants, between the ages of 18 and 60, were included in this study (three ballet dancers, three golfers and four participants from the general population). The participants were assessed randomly by three blinded examiners. All of the participants then received one adjustment delivered by the researcher (half on the symptomatic side and half on the asymptomatic). The participants were then re-assessed. Data was recorded on a data collection sheet and analysed using SPSS version 23. Intra-examiner reliability and clinical responsiveness were analysed using McNemar’s test and the Chi-Square Test of Independence. Inter-examiner reliability was analysed using Fleiss’ Kappa. Results: Intra-examiner reliability showed to be markedly better on the left-hand side for all three examiners. Kappa scores for inter-examiner reliability varied from none to perfect. The average pairwise agreement scores ranged from 33.3% to 100% at the first assessment, and from 46.6% to 100% in the second assessment. A mean and standard deviation were calculated for the pairwise agreements which represented the sensitivity and specificity respectively. Both showed improvement between the first and second assessments which is positive for inter-examiner reliability. Clinical responsiveness was shown to be absent for examiners A and B but was present for examiner C on the left. Conclusion: This study found that, contrary to the expectations of many clinicians, motion palpation has limited to poor levels of intra-examiner reliability, inter-examiner reliability and clinical responsiveness. This is however limited by the small sample size and methodological limitations in this study. Therefore, the role of palpation as a diagnostic tool used in the diagnosis hip dysfunction may be limited.

scholarly journals Co-Metric Learning for Person Re-Identification

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Qingming Leng
Keyword(s):  
Small Sample Size ◽  
Metric Learning ◽  
Distance Matrix ◽  
Small Sample ◽  
Training Task ◽  
Practical Applications ◽  
Single View ◽  
Learning Framework ◽  
Disjoint Camera Views ◽  
Better Than

Person re-identification, aiming to identify the same pedestrian images across disjoint camera views, is a key technique of intelligent video surveillance. Although existing methods have developed both theories and experimental results, most of effective ones pertain to fully supervised training styles, which suffer the small sample size (SSS) problem a lot, especially in label-insufficient practical applications. To bridge SSS problem and learning model with small labels, a novel semisupervised co-metric learning framework is proposed to learn a discriminative Mahalanobis-like distance matrix for label-insufficient person re-identification. Different from typical co-training task that contains multiview data originally, single-view person images are firstly decomposed into pseudo two views, and then metric learning models are produced and jointly updated based on both pseudo-labels and references iteratively. Experiments carried out on three representative person re-identification datasets show that the proposed method performs better than state of the art and possesses low label sensitivity.

scholarly journals Femoral neck strain prediction during level walking using a combined musculoskeletal and finite element model approach

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0245121
Author(s):  
Zainab Altai ◽  
Erica Montefiori ◽  
Bart van Veen ◽  
Margaret A. Paggiosi ◽  
Eugene V. McCloskey ◽  
...  
Keyword(s):  
Finite Element ◽  
Femoral Neck ◽  
Gait Cycle ◽  
Small Sample Size ◽  
Small Sample ◽  
The Body ◽  
Contact Forces ◽  
Principal Strain ◽  
Peak Strain ◽  
Joint Contact

Recently, coupled musculoskeletal-finite element modelling approaches have emerged as a way to investigate femoral neck loading during various daily activities. Combining personalised gait data with finite element models will not only allow us to study changes in motion/movement, but also their effects on critical internal structures, such as the femur. However, previous studies have been hampered by the small sample size and the lack of fully personalised data in order to construct the coupled model. Therefore, the aim of this study was to build a pipeline for a fully personalised multiscale (body-organ level) model to investigate the strain levels at the femoral neck during a normal gait cycle. Five postmenopausal women were included in this study. The CT and MRI scans of the lower limb, and gait data were collected for all participants. Muscle forces derived from the body level musculoskeletal models were used as boundary constraints on the finite element femur models. Principal strains were estimated at the femoral neck region during a full gait cycle. Considerable variation was found in the predicted peak strain among individuals with mean peak first principal strain of 0.24% ± 0.11% and mean third principal strain of -0.29% ± 0.24%. For four individuals, two overall peaks of the maximum strains were found to occur when both feet were in contact with the floor, while one individual had one peak at the toe-off phase. Both the joint contact forces and the muscular forces were found to substantially influence the loading at the femoral neck. A higher correlation was found between the predicted peak strains and the gluteus medius (R2 ranged between 0.95 and 0.99) than the hip joint contact forces (R2 ranged between 0.63 and 0.96). Therefore, the current findings suggest that personal variations are substantial, and hence it is important to consider multiple subjects before deriving general conclusions for a target population.

Probing the ultrastructure of the mitotic and meiotic spindle in eggs: An expeditious approach based on semi-thin (0.25 μm) serial sections

1983 ◽  
Vol 41 ◽  
pp. 552-555
Author(s):  
Conly L. Rieder ◽  
S. Bowser ◽  
R. Nowogrodzki ◽  
K. Ross ◽  
G. Sluder
Keyword(s):  
Small Sample Size ◽  
Small Sample ◽  
Meiotic Spindle ◽  
Serial Sections ◽  
Mitotic Apparatus ◽  
Thin Sections ◽  
Cell Cycles ◽  
Ultrastructural Studies

Eggs have long been a favorite material for studying the mechanism of karyokinesis in-vivo and in-vitro. They can be obtained in great numbers and, when fertilized, divide synchronously over many cell cycles. However, they are not considered to be a practical system for ultrastructural studies on the mitotic apparatus (MA) for several reasons, the most obvious of which is that sectioning them is a formidable task: over 1000 ultra-thin sections need to be cut from a single 80-100 μm diameter egg and of these sections only a small percentage will contain the area or structure of interest. Thus it is difficult and time consuming to obtain reliable ultrastructural data concerning the MA of eggs; and when it is obtained it is necessarily based on a small sample size.We have recently developed a procedure which will facilitate many studies concerned with the ultrastructure of the MA in eggs. It is based on the availability of biological HVEM's and on the observation that 0.25 μm thick serial sections can be screened at high resolution for content (after mounting on slot grids and staining with uranyl and lead) by phase contrast light microscopy (LM; Figs 1-2).

Validating the Factor Structure of the Stigma of Suicide Scale–Short Form Spanish Version Among Healthcare Students

Crisis ◽  
2020 ◽  
pp. 1-5
Author(s):  
Ruthmarie Hernández-Torres ◽  
Paola Carminelli-Corretjer ◽  
Nelmit Tollinchi-Natali ◽  
Ernesto Rosario-Hernández ◽  
Yovanska Duarté-Vélez ◽  
...  
Keyword(s):  
Factor Structure ◽  
Structural Equation ◽  
Short Form ◽  
Small Sample Size ◽  
Small Sample ◽  
Spanish Version ◽  
Equation Modeling ◽  
Cross Sectional ◽  
Healthcare Students ◽  
Spanish Speaking

Abstract. Background: Suicide is a leading cause of death among Spanish-speaking individuals. Suicide stigma can be a risk factor for suicide. A widely used measure is the Stigma of Suicide Scale-Short Form (SOSS-SF; Batterham, Calear, & Christensen, 2013 ). Although the SOSS-SF has established psychometric properties and factor structure in other languages and cultural contexts, no evidence is available from Spanish-speaking populations. Aim: This study aims to validate a Spanish translation of the SOSS-SF among a sample of Spanish-speaking healthcare students ( N = 277). Method: We implemented a cross-sectional design with quantitative techniques. Results: Following a structural equation modeling approach, a confirmatory factor analysis (CFA) supported the three-factor model proposed by Batterham and colleagues (2013) . Limitations: The study was limited by the small sample size and recruitment by availability. Conclusion: Findings suggest that the Spanish version of the SOSS-SF is a valid and reliable tool with which to examine suicide stigma among Spanish-speaking populations.

An Initial Investigation of Suicide Attempt Disclosures Among US Veterans

Crisis ◽  
2020 ◽  
pp. 1-7
Author(s):  
Brooke A. Ammerman ◽  
Sarah P. Carter ◽  
Heather M. Gebhardt ◽  
Jonathan Buchholz ◽  
Mark A. Reger
Keyword(s):  
Suicide Attempt ◽  
Mental Health Professionals ◽  
Help Seeking ◽  
Psychiatric Treatment ◽  
Small Sample Size ◽  
Romantic Partners ◽  
Small Sample ◽  
Professional Care ◽  
Patient Disclosure ◽  
Previous Suicide Attempt

Abstract. Background: Patient disclosure of prior suicidal behaviors is critical for effectively managing suicide risk; however, many attempts go undisclosed. Aims: The current study explored how responses following a suicide attempt disclosure may relate to help-seeking outcomes. Method: Participants included 37 veterans with a previous suicide attempt receiving inpatient psychiatric treatment. Veterans reported on their most and least helpful experiences disclosing their suicide attempt to others. Results: Veterans disclosed their suicide attempt to approximately eight individuals. Mental health professionals were the most cited recipient of their most helpful disclosure; romantic partners were the most common recipient of their least helpful disclosures. Positive reactions within the context of the least helpful disclosure experience were positively associated with a sense of connection with the disclosure recipient. Positive reactions within the most helpful disclosure experience were positively associated with the likelihood of future disclosure. No reactions were associated with having sought professional care or likelihood of seeking professional care. Limitations: The results are considered preliminary due to the small sample size. Conclusion: Findings suggest that while positive reactions may influence suicide attempt disclosure experiences broadly, additional research is needed to clarify factors that drive the decision to disclose a suicide attempt to a professional.

Investigating the Dynamics of Suicidal Ideation

Crisis ◽  
2018 ◽  
Vol 39 (1) ◽  
pp. 65-69 ◽  
Author(s):  
Nina Hallensleben ◽  
Lena Spangenberg ◽  
Thomas Forkmann ◽  
Dajana Rath ◽  
Ulrich Hegerl ◽  
...  
Keyword(s):  
Suicidal Ideation ◽  
Small Sample Size ◽  
Unipolar Depression ◽  
Small Sample ◽  
History Of ◽  
Severity Of Depression ◽  
Ecological Momentary ◽  
Depressive Episodes ◽  
Ema Method ◽  
Shed Light

Abstract. Background: Although the fluctuating nature of suicidal ideation (SI) has been described previously, longitudinal studies investigating the dynamics of SI are scarce. Aim: To demonstrate the fluctuation of SI across 6 days and up to 60 measurement points using smartphone-based ecological momentary assessments (EMA). Method: Twenty inpatients with unipolar depression and current and/or lifetime suicidal ideation rated their momentary SI 10 times per day over a 6-day period. Mean squared successive difference (MSSD) was calculated as a measure of variability. Correlations of MSSD with severity of depression, number of previous depressive episodes, and history of suicidal behavior were examined. Results: Individual trajectories of SI are shown to illustrate fluctuation. MSSD values ranged from 0.2 to 21.7. No significant correlations of MSSD with several clinical parameters were found, but there are hints of associations between fluctuation of SI and severity of depression and suicidality. Limitations: Main limitation of this study is the small sample size leading to low power and probably missing potential effects. Further research with larger samples is necessary to shed light on the dynamics of SI. Conclusion: The results illustrate the dynamic nature and the diversity of trajectories of SI across 6 days in psychiatric inpatients with unipolar depression. Prediction of the fluctuation of SI might be of high clinical relevance. Further research using EMA and sophisticated analyses with larger samples is necessary to shed light on the dynamics of SI.

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