Variability of the Dynamic Stiffness of Foot Joints: Effect of Gait Speed

2019 ◽  
Vol 109 (4) ◽  
pp. 291-298 ◽  
Author(s):  
Enrique Sanchis-Sales ◽  
Joaquín Luis Sancho-Bru ◽  
Alba Roda-Sales ◽  
Javier Pascual-Huerta
Keyword(s):  
Sample Size ◽  
Gait Speed ◽  
Dynamic Stiffness ◽  
Mean Value ◽  
Comparative Analyses ◽  
Foot Joints ◽  
Foot Posture ◽  
The Central Nervous System ◽  
Midtarsal Joint ◽  
Metatarsophalangeal Joints

Background: Comparison of dynamic stiffness of foot joints was previously proposed to investigate pathologic situations with changes in the properties of muscle and passive structures. Samples must be controlled to reduce the variability within groups being compared, which may arise from different sources, such as gait speed or Foot Posture Index (FPI). Methods: Variability in the measurement of the dynamic stiffness of ankle, midtarsal, and metatarsophalangeal joints was studied in a controlled sample of healthy men with normal FPI, and the effect of gait speed was analyzed. In experiment 1, dynamic stiffnesses were obtained in three sessions, five trials per session, for each participant, taking the mean value across trials as representative of each session. In experiment 2, five trials were considered at slow, comfortable, and fast velocities. Results: Similar intersession and intrasession errors and intraparticipant errors within sessions were found, indicating the goodness of using five trials per session for averaging. The intraparticipant and interparticipant variability data provided can be used to select the sample size in future comparative analyses. Significant differences with gait speed were observed in most dynamic stiffnesses considered, with a general rise when gait speed increased, especially at the midtarsal joint, this being attributed to an active modulation produced by the central nervous system. Conclusions: Differences with gait speed were higher than intrasession and intersession repeatability errors for the propulsion phases at the ankle and midtarsal joints; comparative analyses at these phases need more exhaustive control of gait speed to reduce the required sample size.

scholarly journals Effect of static foot posture on the dynamic stiffness of foot joints during walking

2018 ◽  
Vol 62 ◽  
pp. 241-246 ◽  
Author(s):  
E. Sanchis-Sales ◽  
J.L. Sancho-Bru ◽  
A. Roda-Sales ◽  
J. Pascual-Huerta
Keyword(s):  
Dynamic Stiffness ◽  
Foot Joints ◽  
Foot Posture

scholarly journals A Pro-Environmental Method of Sample Size Determination to Predict the Quality Level of Products Considering Current Customers’ Expectations

2021 ◽  
Vol 13 (10) ◽  
pp. 5542
Author(s):  
Dominika Siwiec ◽  
Andrzej Pacana
Keyword(s):  
Sample Size ◽  
Population Based ◽  
Mean Value ◽  
Sample Size Determination ◽  
Quality Level ◽  
High Quality ◽  
Test Power ◽  
The Mean ◽  
Potential Customers ◽  
Main Factor

The main factor that conditions the success of organizations is the development of products oriented toward customer satisfaction. An additional attribute of organizations is the use of sustainable development rules. The use of these rules and the simultaneous desire to create high-quality products encourage organizations to apply different methods to, for example, eliminate waste. This study aimed to develop a method to determine the research sample size required to predict a product’s quality level, taking into account current customers’ expectations. This method was developed by modifying a procedure to determine the research sample size as part of the calculated estimator of the mean value in the general population. Based on the concept of product sustainability development, the goal of the developed method was to determine the number of potential customers (respondents) needed to provide product requirements, which were then processed and used to predict the quality level of the product. This method was applied to simultaneously test a number of hypotheses, determine the test power, and detect statistically significant differences for several relationships of the sample sizes and the test power. This was achieved using universal hypotheses and the popular alternative-punctual (MAP) method. Testing of the proposed method showed that it was able to predict the quality level of products based on current expectations of customers.

scholarly journals KARYOTYPE ANALYSIS IN GRAPEVINES

2016 ◽  
Vol 38 (1) ◽  
pp. 213-221 ◽  
Author(s):  
NEIVA IZABEL PIEROZZI ◽  
MARA FERNANDES MOURA
Keyword(s):  
Karyotype Analysis ◽  
Mean Value ◽  
Comparative Analyses ◽  
Species Diversification

ABSTRACT Seven species of Vitis L., V. champinii Planchon, V. cinerea (Engelm in Gray) Engelm, V. girdiana Munson, V. labrusca L., V. rotundifolia Michaux, V. rupestres Scheels and V. vinifera L. were studied with the purpose of complementing the karyomorphometric information for further comparative analyses. Based on ideograms and on chromosome measures obtained it was possible to see several differences among the species, which were enough to distinguish at least V. champinii and V. girdiana from the others as well as V. labrusca for the lowest measures and V. rotundifolia for the highest mean value of arm ratio. It seems that during the species diversification process the most crucial differences among them did not involve drastic changes in chromosome morphometry.

scholarly journals Weight Bearing CT and Relative Orientation of Foot Bones: Effect of Loading and Heeled Shoes

2020 ◽  
pp. 10-14
Author(s):  
Sandu Elena Cerasela ◽  
Caravaggi Paolo ◽  
Durante Stefano
Keyword(s):  
Sagittal Plane ◽  
Cone Beam Ct ◽  
Young Subject ◽  
Weight Bearing ◽  
Cone Beam ◽  
Non Invasive ◽  
Foot Bones ◽  
Healthy Young Subject ◽  
Foot Posture ◽  
Metatarsophalangeal Joints

The purpose of this article is to determine the orientation and relative position of the foot bones in Weight Bearing CT, highlighting the effect of the load and the shoe with the heel. Thanks to a Cone Beam CT (OnSight 3D Extremity System, Carestream) equipment, three scans of the foot of a healthy young subject were carried out in three conditions: "unloading", "loading", and wearing a shoe with "heel". In order to assess the accuracy of the articular angles of the foot through non-invasive measurements, a measurement was performed by Gait-Analysis with passive markers in the same conditions. The effect of the "load" resulted in a significant alteration of the foot posture especially in the sagittal plane, with crushing of the longitudinal medial arch. The heeled shoe involves enormous deformations at the level of the metatarsophalangeal joints and the ankle.

scholarly journals The effects of gait speed on plantar pressure variables in individuals with normal foot posture and flatfoot

2020 ◽  
Vol 22 (3) ◽  
Author(s):  
Muge Kirmizi ◽  
Yesim S. Sengul ◽  
Salih Angin
Keyword(s):  
Plantar Pressure ◽  
Gait Speed ◽  
Maximum Force ◽  
First Metatarsal ◽  
Fast Speed ◽  
Pressure Sensitive ◽  
Plantar Pressure Distribution ◽  
Second Metatarsal ◽  
Foot Posture ◽  
All Speeds

Purpose: It is not known how gait speed affects plantar pressure characteristics in flatfoot. The aim of this work was to investigate the effects of gait speed on plantar pressure variables in flatfoot by comparing it to normal foot posture. Methods: Thirty individuals with flatfoot and 30 individuals with normal foot posture were recruited. Plantar pressure variables were obtained by a pressure-sensitive mat at self-selected slow, normal, and fast speeds. All assessments were performed on the dominant foot, and three satisfactory steps were obtained for each gait speed condition. The order of gait speeds was randomized. Results: In the flatfoot group, the contact area was higher in the midfoot, third metatarsal, and hallux at all speeds, also in the second metatarsal at slow and normal speeds than the normal foot posture group (p < 0.05). The maximum force was higher in the midfoot and hallux at all speeds in the flatfoot group (p < 0.05). Also, the maximum force was lower in the first metatarsal at normal and fast speeds, and in the lateral heel at fast speed (p < 0.05). In the flatfoot group, the peak pressure was found to be higher in the hallux at slow speed, but to be lower in the first metatarsal at fast speed (p < 0.05). Further, plantar pressure distribution was affected by gait speed in both feet. Conclusions: Analysis of plantar pressure variables should be performed at different gait speeds.

The Measurable Brain

2021 ◽  
pp. 5-16
Author(s):  
Susan D. Healy
Keyword(s):  
Sample Size ◽  
Brain Size ◽  
Evolutionary Analysis ◽  
Comparative Analyses ◽  
Pros And Cons

In this chapter, in order to provide an understanding of the data on which the comparative analyses are based, I describe the methods that have been most commonly used to collect data on brain size. The key to the success of a comparative evolutionary analysis is sample size, the larger the better. To answer the question ‘why do some animals have big brains?’, brains have been measured directly in a variety of ways and brain size has also been inferred (in around half of the analyses) from skull volume. I describe the most commonly used methods briefly, along with the pros and cons of their use and interpretation.

Effects of gait rehabilitation with a footpad-type locomotion interface in patients with chronic post-stroke hemiparesis: a pilot study

2012 ◽  
Vol 26 (8) ◽  
pp. 686-695 ◽  
Author(s):  
Naoki Tanaka ◽  
Hideyuki Saitou ◽  
Toshifumi Takao ◽  
Noboru Iizuka ◽  
Junko Okuno ◽  
...  
Keyword(s):  
Pilot Study ◽  
Sample Size ◽  
Gait Speed ◽  
Chronic Stroke ◽  
Gait Rehabilitation ◽  
Stroke Patients ◽  
Timed Up And Go ◽  
Intervention Phase ◽  
Post Stroke ◽  
Locomotion Interface

Objective: We developed a footpad-type locomotion interface called the GaitMaster. The purpose of this pilot study was to examine the effects of gait rehabilitation using the GaitMaster in chronic stroke patients. Design: Randomized cross-over design. Setting: An outpatient department. Subjects: Twelve patients with chronic post-stroke hemiparesis. Intervention: In group A, patients underwent an ‘intervention phase’ followed by a ‘non-intervention phase’, whereas in group B, patients underwent the non-intervention phase first, followed by the intervention phase. In the four- or six-week intervention phase, participants underwent twelve 20-minute sessions of gait rehabilitation using the GaitMaster4. Main outcome measures: We measured gait speed and timed up-and-go test. Results: No differences between the two groups were observed in the baseline clinical data. For the combined groups A and B, the maximum gait and timed up-and-go test speeds improved significantly only in the intervention phase ( P = 0.0001 and P = 0.003, respectively). The percentages of improvement from baseline at the end of GaitMaster training were 16.6% for the maximum gait speed and 8.3% for the timed up-and-go test. The effect size for GaitMaster4 training was 0.58 on the maximum gait speed and 0.43 on the timed up-and-go test. Conclusions: This pilot study showed that gait rehabilitation using the GaitMaster4 was a feasible training method for chronic stroke patients. Calculation of the sample size indicated that a sample size of 38 participants would be adequate to test a null hypothesis of nil benefit additional to routine rehabilitation for chronic stroke patients in a future randomized controlled trial.

Efferent neurons and suspected interneurons in S-1 vibrissa cortex of the awake rabbit: receptive fields and axonal properties

1989 ◽  
Vol 62 (1) ◽  
pp. 288-308 ◽  
Author(s):  
H. A. Swadlow
Keyword(s):  
Receptive Fields ◽  
Mean Value ◽  
Field Analysis ◽  
Layer 2 ◽  
Efferent Neurons ◽  
High Stimulus ◽  
The Central Nervous System ◽  
Frequency Burst ◽  
Stimulus Site ◽  
Stimulation Of

1. The behavioral tractability of the rabbit was exploited and enabled, in the fully awake state, receptive-field analysis of antidromically identified efferent neurons within the vibrissa representation of primary somatosensory cortex (S-1). Efferent neurons studied included ipsilateral corticocortical neurons (C-IC neurons, n = 56) that project to or beyond the second somatosensory cortical area (S-2) and corticofugal neurons of layer 5 (CF-5 neurons, n = 75) and layer 6 (CF-6 neurons, n = 92) that project to and/or beyond the thalamus. 2. An additional class of neurons was studied that was not activated antidromically from any stimulus site, but which responded synaptically to electrical stimulation of the ventrobasal (VB) thalamus with a burst of three or more spikes at frequencies of 600 to greater than 900 Hz. Most of these neurons also responded synaptically to stimulation of S-2. The action potentials of these neurons were much shorter (mean = 0.43 ms), than those of efferent neurons (mean = 0.98 ms). Such properties have been associated with interneurons found throughout the central nervous system, and these neurons are thereby referred to as suspected interneurons (SINs). Although SINs were found at all cortical depths, a strong peak in the distribution occurred just superficial to the peak in the distribution of CF-5 neurons. Most SINs located within this peak responded to deflection of only a single vibrissa. In contrast, SINs located in layer 6 and in layer 2-3 responded to deflection of many vibrissae (median = 11.0 and 5.5 vibrissae, respectively). In addition, SINs of layer 6 and layer 2-3 had significantly longer synaptic latencies to stimulation of VB thalamus than did SINs located at intermediate cortical depths. 3. The properties of efferent neurons and SINs differed considerably. Efferent neurons never responded to stimulation of VB thalamus with the high-frequency burst of spikes characteristic of SINs. Although greater than 70% of CF-6, CF-5 and C-IC neurons had receptive fields that were directionally selective, only 20% of SINs showed any degree of directional selectivity. Furthermore, SINs showed both much lower angular thresholds to vibrissa deflection and a much greater ability to follow high-stimulus frequencies than was seen in efferent neurons. The spontaneous firing rates of SINs had a mean value of 16.5 spikes/s, which was the highest seen in any population within S-1. 4. CF-5 neurons had a number of properties which contrasted with those of both CF-6 and C-IC neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Bundle-Specific Axon Diameter Index as a New Contrast to Differentiate White Matter Tracts

2021 ◽  
Vol 15 ◽  
Author(s):  
Muhamed Barakovic ◽  
Gabriel Girard ◽  
Simona Schiavi ◽  
David Romascano ◽  
Maxime Descoteaux ◽  
...  
Keyword(s):  
White Matter ◽  
Internal Capsule ◽  
Mean Value ◽  
Axon Diameter ◽  
Posterior Limb ◽  
Weighted Magnetic Resonance Imaging ◽  
The Central Nervous System ◽  
Index Value ◽  
White Matter Connectivity

In the central nervous system of primates, several pathways are characterized by different spectra of axon diameters. In vivo methods, based on diffusion-weighted magnetic resonance imaging, can provide axon diameter index estimates non-invasively. However, such methods report voxel-wise estimates, which vary from voxel-to-voxel for the same white matter bundle due to partial volume contributions from other pathways having different microstructure properties. Here, we propose a novel microstructure-informed tractography approach, COMMITAxSize, to resolve axon diameter index estimates at the streamline level, thus making the estimates invariant along trajectories. Compared to previously proposed voxel-wise methods, our formulation allows the estimation of a distinct axon diameter index value for each streamline, directly, furnishing a complementary measure to the existing calculation of the mean value along the bundle. We demonstrate the favourable performance of our approach comparing our estimates with existing histologically-derived measurements performed in the corpus callosum and the posterior limb of the internal capsule. Overall, our method provides a more robust estimation of the axon diameter index of pathways by jointly estimating the microstructure properties of the tissue and the macroscopic organisation of the white matter connectivity.

scholarly journals Assessing terpene content variability of whitebark pine in order to estimate representative sample size

2013 ◽  
pp. 193-204
Author(s):  
Milena Stefanovic ◽  
Slobodanka Mitrovic ◽  
Dragica Obratov-Petkovic ◽  
Vera Vidakovic ◽  
Zorica Popovic ◽  
...  
Keyword(s):  
Sample Size ◽  
Representative Sample ◽  
Mean Value ◽  
Whitebark Pine ◽  
Initial Sample ◽  
Basic Set ◽  
Chemical Content ◽  
The Mean ◽  
Selection Of

In studies of population variability, particular attention has to be paid to the selection of a representative sample. The aim of this study was to assess the size of the new representative sample on the basis of the variability of chemical content of the initial sample on the example of a whitebark pine population. Statistical analysis included the content of 19 characteristics (terpene hydrocarbons and their derivates) of the initial sample of 10 elements (trees). It was determined that the new sample should contain 20 trees so that the mean value calculated from it represents a basic set with a probability higher than 95 %. Determination of the lower limit of the representative sample size that guarantees a satisfactory reliability of generalization proved to be very important in order to achieve cost efficiency of the research.

Sign in / Sign up

Export Citation Format

Share Document