scholarly journals Scaling of Dynamics in the Earliest Stages of Walking

2007 ◽  
Vol 87 (11) ◽  
pp. 1458-1467 ◽  
Author(s):  
Kenneth G Holt ◽  
Elliot Saltzman ◽  
Chia-Ling Ho ◽  
Beverly D Ulrich
Keyword(s):  
Developmental Delays ◽  
Physical Therapist ◽  
Equations Of Motion ◽  
Fine Tuning ◽  
Spring Stiffness ◽  
Kinematic Data ◽  
Ground Testing ◽  
Stage Process ◽  
Study Participants ◽  
Isometric Muscle

Background and Purpose Although the description of mature walking is fairly well established, less is known about what is being learned in the process. Such knowledge is critical to the physical therapist who wants to teach children with developmental delays. The purpose of this experiment was to test the notion that learning to walk efficiently involves fine-tuning the body’s controllable stiffness (by co-contraction and isometric muscle contractions against gravity) to match (at a 1:1 scaling) the gravitational (pendular) stiffness of the swing leg. Subjects The study participants were 7 children with typical development and the newly emerged ability to walk 6 steps without falling (ages 11 months to 1 year 5 months at the onset of walking). Methods Pendular stiffness and spring stiffness were estimated from the equations of motion for a hybrid model with kinematic data as children walked over ground. Testing occurred once per month for the first 7 months of walking. Results After the first month of walking, children walked with greater spring stiffness than would be predicted by the model. The ratio began to approach the predicted value (1:1) as the months progressed. Discussion and Conclusion The results of this and a previous study of the pendular dynamics of gait suggest that learning to walk is a 2-stage process. The first stage involves the child’s discovery of how to conserve energy by inputting a particular muscular force at the correct moment in the cycle. The second stage involves the fine-tuning of the soft-tissue stiffness that takes advantage of the resonance characteristics of tissues. In order to address developmental delays, investigators must discover the dynamic resources used for the activity and attempt to foster their development. A number of interventions that probe this approach are discussed.

scholarly journals Efeitos da crioterapia e da diatermia por micro-ondas sobre a capacidade de produção de força de flexores de cotovelo de homens saudáveis

2016 ◽  
Vol 18 (3) ◽  
pp. 332
Author(s):  
Juliana Carvalho Schleder ◽  
Andrelize Müller ◽  
Walkyria Vilas Boas Fernandes ◽  
Andrielle Elaine Capote
Keyword(s):  
Production Capacity ◽  
Peak Strength ◽  
Isometric Strength ◽  
The Other ◽  
Significant Difference ◽  
Thermal Changes ◽  
Study Participants ◽  
Sedentary Subjects ◽  
Isometric Muscle ◽  
Microwave Diathermy

DOI: http://dx.doi.org/10.5007/1980-0037.2016v18n3p332 Physiological effects of thermal changes in tissues might influence some physical properties of muscle fibers, such as strength. The aim of this study was to compare the effects of cryotherapy and microwave diathermy application on the strength production capacity of the elbow flexor muscles. Thirty male, healthy and sedentary subjects, with average age of 22.40 (±3.42) years, participated in this prospective study. Participants were submitted to assessment of isometric strength production capability by an adapted load cell. Half of volunteers received cryotherapy on the first day of application and microwave diathermy (MD) 48 hours later, whereas the other half was treated the other way around. Cryotherapy was applied up to the temperature of the biceps region reached 25ºC, and MD was applied up to 42ºC. Six peak strength reevaluations were made over 2 hours. There was significant increase in peak strength (PS) up to 15 minutes after cryotherapy, then there was a decrease in maximum isometric strength, however, statistically significant difference remained up to 1 hour and 30 minutes after cryotherapy. In MD, PS decreased significantly after application until 15 min. From this moment, PS returned close to the initial value, and in the last assessment, PS reduced again. Cryotherapy and MD differently interfered in isometric muscle strength production capacity of elbow flexors, while cooling generated increment, heating caused decline.

Neural Correlates of Morphological Processes in Hebrew

2008 ◽  
Vol 20 (3) ◽  
pp. 406-420 ◽  
Author(s):  
Atira Bick ◽  
Gadi Goelman ◽  
Ram Frost
Keyword(s):  
Imaging Study ◽  
Semantic Relatedness ◽  
Neural Substrates ◽  
Statistical Correlation ◽  
Morphological Processing ◽  
Fine Tuning ◽  
Orthographic Similarity ◽  
Distinct Process ◽  
Study Participants ◽  
Semantic Properties

Is morphology a discrete and independent element of lexical structure or does it simply reflect a fine tuning of the system to the statistical correlation that exists among the orthographic and semantic properties of words? Imaging studies in English failed to show unequivocal morphological activation that is distinct from semantic or orthographic activation. Cognitive research in Hebrew has revealed that morphological decomposition is an important component of print processing. In Hebrew, morphological relatedness does not necessarily induce a clear semantic relatedness, thus, Hebrew provides a unique opportunity to investigate the neural substrates of morphological processing. In this functional magnetic resonance imaging study, participants were required to perform judgment tasks of morphological relatedness, semantic relatedness, rhyming, and orthographic similarity. Half of the morphologically related words were semantically related and half were semantically unrelated. This design was chosen to induce explicit morphological processing. We identified two locations involved in morphological processing: the left middle frontal gyrus and the left inferior parietal sulcus. Comparing locations of morphological related activation to the locations of semantic and orthographic related activation, we found that the areas neighbored but only partially overlapped. The similarity in activation between the two morphological conditions eliminates the possibility that morphological activation simply results from the semantic properties of the words. These results demonstrate the important role of morphological processing in reading and suggest that morphological analysis is a distinct process of visual word recognition.

Vehicle Moving Along an Infinite Beam With Random Surface Irregularities on a Kelvin Foundation

2001 ◽  
Vol 69 (1) ◽  
pp. 69-75 ◽  
Author(s):  
L. Andersen ◽  
S. R. K. Nielsen ◽  
R. Iwankiewicz
Keyword(s):  
Equations Of Motion ◽  
Response Functions ◽  
Spring Stiffness ◽  
Euler Beam ◽  
Random Surface ◽  
Single Degree Of Freedom ◽  
Surface Irregularities ◽  
Stiffness And Damping Coefficient ◽  
Mass Spring ◽  
Stiffness And Damping

The paper deals with the stochastic analysis of a single-degree-of-freedom vehicle moving at a constant velocity along an infinite Bernoulli-Euler beam with surface irregularities supported by a Kelvin foundation. Both the Bernoulli-Euler beam and the Kelvin foundation are assumed to be constant and deterministic. This also applies to the mass, spring stiffness, and damping coefficient of the vehicle. At first the equations of motion for the vehicle and beam are formulated in a coordinate system following the vehicle. The frequency response functions for the displacement of the vehicle and beam are determined for harmonically varying surface irregularities. Next, the surface irregularities are modeled as a random process. The variance response of the mass of the vehicle as well as the displacement variance of the beam under the oscillator are determined in terms of the autospectrum of the surface irregularities.

scholarly journals Facilitators and Barriers for Using Outcome Measuring Tools in Physical Therapy Practice

2021 ◽  
Vol 15 (6) ◽  
pp. 2126-2129
Author(s):  
Rahat Ayub ◽  
Somia Sabeeh Awan ◽  
Muhamamd Rizwan ◽  
Rabia Majeed ◽  
Rabia Jawa ◽  
...  
Keyword(s):  
Physical Therapy ◽  
Key Words ◽  
Outcome Measures ◽  
Physical Therapist ◽  
Assessment Tools ◽  
The Other ◽  
Study Population ◽  
Facilitators And Barriers ◽  
Study Participants ◽  
E Mail

Objective: The study was conducted toascertain the percentage of physiotherapist who were utilizing the outcome measures during the treatment of patients and to find the factors which were potentiating the physiotherapists in implementing the outcome measuring tools in the treatment of their patients. On the other hand, such factors were also looked into which were considered as obstacles by the physiotherapists in the use of the tools. Methodology: The estimated study population size was 242. Data was collected through e-mail as well as through one-on-one meeting with the physiotherapists by using a standard questionnaire (appendix I) and was analyzed through SPSS version 20. Results: It was found that 78 percent of the study participants were using the outcome measures in the assessments of the patients and for finding the progression in their condition. The feeling of the patient about the keen involvement of the physiotherapist in his treatment, enhanced communication between two of them and increased efficiency of examination were the major facilitators which urged the physiotherapists to use outcome measures in their practice. The most frequent barriers seen were the duration required by physiotherapist to analyze the score and duration of patient to complete it. Conclusion: The main facilitators are increased communication between physiotherapist and patient and enhanced the efficacy of assessment. Alternatively, the main barriers restricting the usage of outcome measures are reported to be the inability to complete the various assessment tools due to the lack of time on the part of the patient as well as the physical therapist. Key words: Outcome measures, Outcomes measuring tools, Facilitators, Barriers, Physical therapist, Physiotherapist

scholarly journals Investigating the Effect of Low Speed Impact on Sandwich Panel with Metal Foam Core (Comparing the Results of MATLAB and Abacus Analysis)

2020 ◽  
Vol 6 (5) ◽  
pp. 45-52
Author(s):  
Hamed Farhadi Nai
Keyword(s):  
Analytical Modeling ◽  
Sandwich Panel ◽  
Metal Foam ◽  
Equations Of Motion ◽  
Sandwich Panels ◽  
Foam Core ◽  
Spring Stiffness ◽  
Mass Model ◽  
Low Speed ◽  
Three Samples

In this paper, analytical modeling and numerical simulation of sandwich panel behavior with metal foam core under low impact impact are presented and how the formation and development of impact defects in impact loading conditions in three samples with different face sizes Taken, checked. Multi-layer sandwich panels are made of epoxy carbon and the core is also made of metal foam. Analytical modeling of low speed shock load on sandwich panels, using mass model and two-degree free spring, has been used to calculate the contact force. The spring stiffness of the contact site, and the bending and shear spring stiffness of the sandwich panel are calculated, the values of which change over time. To solve the equations of motion, the exact solution method has been used and the radius of the affected area is calculated using energy equations. In the next section, simulation of low speed impact on sandwich panels with metal foam core is done in three samples of different sizes in Abacus software, so that we see how to create and develop defects in sandwich panels. In the next section, we have examined the results and compared the numerical solution and analytical simulation, which confirms the process of research and this has been proven to be important.

Stability and vibration of a non-linear vehicle and passenger system

2002 ◽  
Vol 216 (2) ◽  
pp. 109-116 ◽  
Author(s):  
K Yu ◽  
A C J Luo ◽  
Y He
Keyword(s):  
Equations Of Motion ◽  
Linear Equations ◽  
Dynamic Responses ◽  
Spring Stiffness ◽  
Torsional Spring ◽  
Non Linear ◽  
Linear Equations Of Motion ◽  
Safety Belts ◽  
The Stability ◽  
Non Linear Equations

A non-linear dynamic model to predict the passenger's response in a vehicle travelling on a rough pavement surface (or a rough terrain) is developed. The corresponding equilibrium and stability are investigated through the non-linear equations of motion for a vehicle and passenger system with impacts. The stability with respect to the torsional spring stiffness of safety belts is illustrated. Based on such a stability condition, the dynamic responses for the vehicle and passenger system with and without impacts are simulated numerically. This investigation shows that a strong torsional spring is required in order to reduce the vibration amplitudes of passengers and to avoid impacts between the vehicle and passenger.

Stiffness Optimization for Springs in a Gun Cartridge Retaining Mechanism

2013 ◽  
Vol 385-386 ◽  
pp. 163-167
Author(s):  
Long Miao Chen ◽  
Lin Fang Qian ◽  
Rui Xue Zhao
Keyword(s):  
Optimization Design ◽  
Design Research ◽  
Simulation Analysis ◽  
Equations Of Motion ◽  
Parameters Optimization ◽  
Design Parameters ◽  
Evaluation Function ◽  
Spring Stiffness ◽  
Original Design ◽  
Design Variables

To prolong the life of cartridge retaining pawl and link stopper in a gun cartridge retaining Mechanism, three compression springs stiffness are reduced via design study and optimization design based on dynamic analysis. Presenting the load of shell on a typical stage while entering-bore, differential equations of motion in this mechanism are established. With translational velocity of shell as the design variable, a design research and simulation analysis are made. And the relationship between shell velocity and proper shell-feed is acquired. An evaluation function is built using springs stiffness with preference-selection. With this evaluation function as the optimum objective, spring stiffness as design variables, and proper shell-feed as constraint condition, the minimum of three spring stiffness is obtained after calculation. The results indicate that compared with the original design parameters optimization results, are significantly improved with the stiffness decreased separately by 20.27%, 11.99% and 6.86%.

The Effects of Duration and Frequency of Achilles Tendon Stretching on Dorsiflexion and Outcome in Painful Heel Syndrome: A Randomized, Blinded, Control Study

2002 ◽  
Vol 23 (7) ◽  
pp. 619-624 ◽  
Author(s):  
David Porter ◽  
Erin Barrill ◽  
Kathy Oneacre ◽  
Benjamin D. May
Keyword(s):  
Achilles Tendon ◽  
Physical Therapist ◽  
Significant Difference ◽  
Blinded Study ◽  
American Orthopaedic ◽  
Study Participants ◽  
Monthly Visit ◽  
Control Study ◽  
Stretching Exercises ◽  
Painful Heel

The American Orthopaedic Foot and Ankle Society recommends at least six months of nonsurgical treatment before considering surgical intervention for painful heel syndrome. Achilles tendon stretching exercises are consistently reported to be one of the more effective nonsurgical modalities for treatment of painful heel syndrome. However, the optimal duration and frequency of the exercises has not been reported. The purpose of this study was to evaluate and compare the effectiveness of sustained and intermittent Achilles tendon stretching for the relief of pain associated with painful heel syndrome. This prospective, randomized, blinded study was performed from May 1997 to July 2000. A total of 94 people (122 affected feet) fit the inclusion criterion and agreed initially to participate in a treatment study group. To achieve our purpose, study participants were randomized into two stretching groups. One group performed sustained Achilles tendon stretches (three minutes, three times daily), the other performed intermittent stretches (five sets, 20 seconds each, two times daily). Participants were evaluated once a month for a period of four months subsequent to diagnosis. At each monthly visit, participants completed subjective questionnaires about their pain. Also, a physical therapist measured each participant's Achilles tendon flexibility. The study determined that both sustained and intermittent Achilles tendon stretching exercises increase Achilles tendon flexibility. This increase in flexibility correlated with a decrease in pain. There was no significant difference in outcome between the sustained and intermittent stretching groups. The data suggest that both sustained and intermittent Achilles tendon stretching exercises were effective nonsurgical treatments for painful heel syndrome.

Derivation and reliability of kinematic measures of sperm motion

1995 ◽  
Vol 7 (4) ◽  
pp. 857 ◽  
Author(s):  
RO Davis ◽  
RJ Siemers
Keyword(s):  
Equations Of Motion ◽  
Biological Mechanisms ◽  
Kinematic Data ◽  
Head Kinematics ◽  
Accuracy And Precision ◽  
Engineering Measures ◽  
Kinematic Measures ◽  
Sperm Motion ◽  
Standard Techniques ◽  
Sperm Movement

Studies of sperm movement are relevant in the diagnosis of sperm function and in investigations of cellular biology. Such studies have been traditionally performed by analysing the kinematics of the flagellum or the head. Analysis of the flagellum can provide insights into the cell biological mechanisms responsible for the control of movement. However, the mathematical correspondence between head kinematics and flagellum kinematics is not unique. Therefore, it is not possible to use head kinematics to obtain detailed insights into cell mechanisms or physiology. The accuracy and precision of kinematic measurements are limited by a number of technical and biological factors. Therefore, the interpretation of kinematic data is dependent on a thorough understanding of the assumptions and conditions underlying the analysis. Evaluation of the reliability of kinematic measurements has suffered because no absolute standard for measurement has existed. The development and application of a new standard based on images which were simulated using the equations of motion is described. Because the kinematics of these images are known prior to empirical measurement, the performance of different methods can be determined absolutely. Some kinematic measures are unreliable because they are inappropriate analogues for engineering concepts. The development and use of appropriate engineering measures for the frequency and amplitude of sperm motion is also described. Some types of sperm motion cannot be analysed using kinematic measures (e.g. hyperactivated movement). The concept of the fractal dimension as a more accurate measurement for such motions is introduced. It is concluded that kinematic measurements of sperm motion can provide valuable information about cell biological mechanisms (in the case of the flagellum) and about general membrane and axoneme function (in the case of the head) when the measurements are made under the appropriate conditions, when standard techniques are followed, and when the assumptions underlying the analysis are well understood.

The Effect of Nonlinear Springs in Jumping Mechanisms

2018 ◽  
Author(s):  
Sahand Sadeghi ◽  
Blake D. Betsill ◽  
Phanindra Tallapragada ◽  
Suyi Li
Keyword(s):  
Piecewise Linear ◽  
Equations Of Motion ◽  
Piecewise Linear Function ◽  
Displacement Curve ◽  
Spring Stiffness ◽  
Nonlinear Spring ◽  
Jumping Performance ◽  
Nonlinear Springs ◽  
Nonlinear Force ◽  
Force Displacement

This research investigates the potential effects of utilizing nonlinear springs on the performance of robotic jumping mechanisms. As a theoretical example, we study dynamic characteristics of a jumping mechanism consisting of two masses connected by a generic nonlinear spring, which is characterized by a piecewise linear function. The goal of this study is to understand how the nonlinearity in spring stiffness can impact the jumping performance. To this end, non-dimensional equations of motion of the jumping mechanism are derived and then used extensively for both analytical and numerical investigations. The nonlinear force-displacement curve of the spring is divided into two sections: compression and tension. We examine the influences of these two sections of spring stiffness on the overall performance of the jumping mechanism. It is found that compression section of the nonlinear spring can significantly increase energy storage and thus enhance the jumping capabilities dramatically. We also found that the tension section of the nonlinear force-displacement curve does not affect the jumping performance of the center of gravity, however, it has a significant impact on the internal oscillations of the mechanism. Results of this study can unfold the underlying principles of harnessing nonlinear springs in jumping mechanisms and may lead to the emergence of more efficient hopping and jumping systems and robots in the future.

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