scholarly journals Scaling of inertial delays in terrestrial mammals

2019 ◽  
Author(s):  
Sayed Naseel Mohamed Thangal ◽  
J. Maxwell Donelan
Keyword(s):  
Full Range ◽  
Whole Body ◽  
Range Of Movement ◽  
Stimulus Response ◽  
Moment Arms ◽  
Terrestrial Mammals ◽  
Biomechanical Models ◽  
Elapsed Time ◽  
Animal Size ◽  
Body Inertia

AbstractAs part of its response to a perturbation, an animal often needs to reposition its body. Inertia acts to oppose motion, delaying the completion of the movement—we refer to this additional elapsed time as inertial delay. As animal size increases, muscle moment arms also increase, but muscles are proportionally weaker, and limb inertia is proportionally larger. Consequently, the scaling of inertial delays is complex. Here, we quantify it using two biomechanical models representing common scenarios in animal locomotion: a distributed mass pendulum approximating swing limb repositioning (swing task), and an inverted pendulum approximating whole body posture recovery (posture task). We parameterized the anatomical, muscular, and inertial properties of these models using literature scaling relationships, then determined inertial delay for each task across a large range of movement magnitudes and the full range of terrestrial mammal sizes. We found that inertial delays scaled with an average of M0.28 in the swing task and M0.35 in the posture task across movement magnitudes—larger animals require more absolute time to perform the same movement as small animals. The time available to complete a movement also increases with animal size, but less steeply. Consequently, inertial delays comprise a greater fraction of swing duration and other characteristic movement times in larger animals. We also compared inertial delays to the other component delays within the stimulus-response pathway. As movement magnitude increased, inertial delays exceeded these sensorimotor delays, and this occurred for smaller movements in larger animals. Inertial delays appear to be a challenge for motor control, particularly for bigger movements in larger animals.

Shoulder examination: a systematic approach

2021 ◽  
pp. 1-15
Author(s):  
Akib M Khan ◽  
Angelos Assiotis ◽  
Mazin S Ibrahim ◽  
Andrew R Sankey
Keyword(s):  
Rotator Cuff ◽  
Systematic Approach ◽  
Healthcare Professionals ◽  
Full Range ◽  
Range Of Movement ◽  
Systematic Examination ◽  
Complex Joint ◽  
Different Levels ◽  
Shoulder Examination

The shoulder is a complex joint with static and dynamic stabilising structures working synchronously. These allow a full range of movement while preserving stability of the joint. Patients may present with pain, stiffness, weakness, deformity or instability. The authors suggest a systematic examination sequence to ensure that important pathology is not overlooked. Adopting this approach allows common pathologies, including tears of the rotator cuff, impingement and tendinopathy, to be easily identified. This shoulder examination sequence may be used by all healthcare professionals and can also act as a revision aid for those undergoing exams in this field, at different levels of training.

Impact of Age and Body Mass Index on Anthropometry in Working Adults

2017 ◽  
Vol 61 (1) ◽  
pp. 1341-1345 ◽  
Author(s):  
Zachary Merrill ◽  
April Chambers ◽  
Rakié Cham
Keyword(s):  
Body Mass Index ◽  
Body Mass ◽  
Center Of Mass ◽  
Biomechanical Model ◽  
Whole Body ◽  
Working Adults ◽  
Biomechanical Models ◽  
Scan Data ◽  
Body Segment Parameters ◽  
The Impact

Body segment parameters (BSPs) such as segment mass and center of mass are used as inputs in ergonomic design and biomechanical models to predict the risk of musculoskeletal injuries. These models have been shown to be sensitive to the BSP values used as inputs, demonstrating the necessity of using accurate and representative parameters. This study aims to provide accurate BSPs by quantifying the impact of age and body mass index on torso and thigh mass and center of mass in working adults using whole body dual energy x-ray absorptiometry (DXA) scan data. The results showed significant effects of gender, age, and body mass index (BMI) on torso and thigh mass and center of mass, as well as significant effects of age and BMI within genders, indicating that age, gender, and BMI need to be taken into account when predicting BSPs in order to calculate representative ergonomic and biomechanical model outputs.

scholarly journals Dynamics of the IFT machinery at the ciliary tip

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Alexander Chien ◽  
Sheng Min Shih ◽  
Raqual Bower ◽  
Douglas Tritschler ◽  
Mary E Porter ◽  
...  
Keyword(s):  
Basal Body ◽  
Full Range ◽  
Intraflagellar Transport ◽  
Feedback Mechanism ◽  
Conventional Imaging ◽  
Range Of Movement ◽  
Anterograde Transport ◽  
Traffic Jam ◽  
Negative Feedback Mechanism ◽  
Cilia And Flagella

Intraflagellar transport (IFT) is essential for the elongation and maintenance of eukaryotic cilia and flagella. Due to the traffic jam of multiple trains at the ciliary tip, how IFT trains are remodeled in these turnaround zones cannot be determined by conventional imaging. Using PhotoGate, we visualized the full range of movement of single IFT trains and motors in Chlamydomonas flagella. Anterograde trains split apart and IFT complexes mix with each other at the tip to assemble retrograde trains. Dynein-1b is carried to the tip by kinesin-II as inactive cargo on anterograde trains. Unlike dynein-1b, kinesin-II detaches from IFT trains at the tip and diffuses in flagella. As the flagellum grows longer, diffusion delays return of kinesin-II to the basal body, depleting kinesin-II available for anterograde transport. Our results suggest that dissociation of kinesin-II from IFT trains serves as a negative feedback mechanism that facilitates flagellar length control in Chlamydomonas.

scholarly journals Controversies In The Surgical Management Of Shoulder Instability: Associated Soft Tissue Procedures

2017 ◽  
Vol 11 (1) ◽  
pp. 989-1000 ◽  
Author(s):  
Santos Moros Marco ◽  
José Luis Ávila Lafuente ◽  
Miguel Angel Ruiz Ibán ◽  
Jorge Diaz Heredia
Keyword(s):  
Soft Tissue ◽  
Rotator Cuff ◽  
Shoulder Instability ◽  
Full Range ◽  
Rotator Interval ◽  
Range Of Movement ◽  
Slap Repair ◽  
Rotator Cuff Injuries ◽  
Complex Anatomy ◽  
Pubmed Database

Background:The glenohumeral joint is a ball-and-socket joint that is inherently unstable and thus, susceptible to dislocation. The traditional and most common anatomic finding is the Bankart lesion (anterior-inferior capsule labral complex avulsion), but there is a wide variety of anatomic alterations that can cause shoulder instability or may be present as a concomitant injury or in combination, including bone loss (glenoid or humeral head), complex capsule-labral tears, rotator cuff tears, Kim´s lesions (injuries to the posterior-inferior labrum) and rotator interval pathology.Methods:A review of articles related to shoulder anatomy and soft tissue procedures that are performed during shoulder instability arthroscopic management was conducted by querying the Pubmed database and conclusions and controversies regarding this injury were exposed.Results:Due to the complex anatomy of the shoulder and the large range of movement of this joint, a wide variety of anatomic injuries and conditions can lead to shoulder instability, specially present in young population. Recognizing and treating all of them including Bankart repair, capsule-labral plicatures, SLAP repair, circumferential approach to pan-labral lesions, rotator interval closure, rotator cuff injuries and HAGL lesion repair is crucial to achieve the goal of a stable, full range of movement and not painful joint.Conclusion:Physicians must be familiarized with all the lesions involved in shoulder instability, and should be able to recognize and subsequently treat them to achieve the goal of a stable non-painful shoulder. Unrecognized or not treated lesions may result in recurrence of instability episodes and pain while overuse of some of the techniques previously described can lead to stiffness, thus the importance of an accurate diagnosis and treatment when facing a shoulder instability.

Gait Analysis Using Multibody Simulation Tools and Inverse Dynamics Procedures

2005 ◽  
Author(s):  
Miguel Silva ◽  
Jorge Ambro´sio
Keyword(s):  
Gait Analysis ◽  
Inverse Dynamics ◽  
Three Dimensional ◽  
Biomechanical Model ◽  
Whole Body ◽  
Dynamics Analysis ◽  
Natural Coordinates ◽  
Kinematic Constraints ◽  
Biomechanical Models ◽  
Inverse Dynamics Analysis

The use of inverse dynamics methodologies for the evaluation of intersegmental reaction forces and the moments-of-force at the anatomical joints, in the framework of gait analysis, not only requires that appropriate biomechanical models are used but also that kinematic and kinetic data sets are available. This paper discusses the quality of the results of the inverse dynamics analysis with respect to the filtering procedures used and the kinematic consistency of the position, velocity and acceleration data. A three-dimensional whole body response biomechanical model based on a multibody formulation with natural coordinates is used. The model has 16 anatomical segments that are described using 33 rigid bodies in a total of 44 degrees-of-freedom. In biomechanical applications, one of the advantages of the current formulation is that the set of anatomical points used to reconstruct the spatial motion of the subject is also used to construct the set of natural coordinates that describe the biomechanical model itself. Based on the images collected by four synchronized video cameras, the three-dimensional trajectories of the anatomical points are reconstructed using standard photogrammetry techniques and Direct Linear Transformations. The trajectories obtained are then filtered in order to reduce the noise levels introduced during the reconstruction procedure using 2nd order Butterworth low-pass filters with properly chosen cut-off frequencies. The filtered data is used in the inverse dynamics analysis either directly or after being modified in order to ensure its consistency with the biomechanical model’s kinematic constraints. It is also shown that the use of velocities and accelerations consistent with the kinematic constraints or those obtained through the time derivatives of the spline interpolation curves of the reconstructed trajectories lead to similar results.

Condylar fractures of the proximal and middle phalanges

2013 ◽  
Vol 40 (1) ◽  
pp. 51-58 ◽  
Author(s):  
D. J. Shewring ◽  
A. C. Miller ◽  
A. Ghandour
Keyword(s):  
Internal Fixation ◽  
Full Range ◽  
Day Surgery ◽  
Nonoperative Treatment ◽  
Lateral Approach ◽  
Close Monitoring ◽  
Range Of Movement ◽  
Distal Interphalangeal ◽  
Condylar Fractures ◽  
Extensor Lag

We describe the treatment of 74 patients with phalangeal condylar fractures. Twelve patients presenting with undisplaced fractures were initially treated nonoperatively; of these, five displaced, requiring fixation. The remaining seven patients, all children, united uneventfully. Sixty-two patients presenting with displaced fractures were treated with internal fixation using a single lag screw through a lateral approach. The patients were treated semi-electively on a day surgery unit. Twenty-seven patients with unicondylar fractures, all operated on within 2 weeks of injury, regained full range of movement. Thirty-eight patients had loss of extension (range 10–35°) with fixed flexion contractures at the proximal interphalangeal and thumb interphalangeal joints and extensor lag at the distal interphalangeal joints (overall mean extension loss 10°). Although fixation was technically easier during the first week, a delay of 2 weeks before fixation made little difference to the outcome. In our experience, fractures can be taken down and fixed internally even 8 weeks after injury. If nonoperative treatment is initially embarked upon, close monitoring is required with weekly radiographs up to 3 weeks, as these fractures will frequently displace.

scholarly journals P12 Focal myositis—A case series of a rare cause of hip immobility and calf pseudotumor in children

2021 ◽  
Vol 5 (Supplement_1) ◽  
Author(s):  
Fahim Patel ◽  
Arani Sridhar
Keyword(s):  
Case Report ◽  
External Rotation ◽  
Full Range ◽  
Case Series ◽  
Joint Involvement ◽  
Inflammatory Cell Infiltrate ◽  
Eye Drops ◽  
Range Of Movement ◽  
Obturator Internus ◽  
Rare Differential Diagnosis

Abstract Case report - Introduction Focal myositis is a rare immune-mediated pseudotumour of a single skeletal muscle group. Only around 200 cases have been described in the literature, so little is known about incidence, prevalence, patient management and outcomes. This differs and should not be confused with post-viral myalgia which bears neither the histological changes nor chronicity of focal myositis. Treatment options are centred on immunomodulation and in severe cases surgical management of contractures. Case report - Case description Case 1 A systemically well 7-year-old girl presented with 5-weeks of right calf tenderness and swelling following a short episode of pharyngitis and generalised maculopapular rash. There was no gait abnormality, focal neurology or restriction in activity aside from fatigability on walking distances. There were no skin rashes, joint involvement, eye changes or involvement of other muscles. She had a raised creatine kinase, plasma viscosity and lactate dehydrogenase. Her other blood results were normal including an extended autoimmune screen, immunoglobulins, complement levels, ASOT and titres of mycoplasma, EBV and CMV. MRI showed evidence of extensive inflammation of the gastrocnemius and soleus. A muscle biopsy showed heavy interstitial inflammatory cell infiltrate of predominantly lymphocytes, features of fibre necrosis including phagocytosis and hyalinisation with concurrent fibre regeneration. Case 2 A systemically well 14-year-old presented with 6-months of left-sided hip pain, weight loss and inability to weight-bear without crutches. On examination there was painful fixed limitation of the left hip to 45o on abduction and external rotation with bilateral mild swelling of the proximal interphalangeal (PIP) joints on both upper limbs. Otherwise, there was a full range of movement in all joints, with no rashes or other joint swelling or inflammation. Her blood tests were ANA positive 1:6000 and MRI of her hips demonstrated high T2 signal intensity in the left gluteus minimis and medius, obturator internus, obturator externus in keeping with myositis. Case report - Discussion Case 1 She was initially managed with physiotherapy and anti-inflammatory medications but then developed intermittent right calf pain, restriction in activity and tiptoe walking due to gastrocnemius contractures. She was commenced on an 8-week tapering course of oral steroids and is improving with weekly methotrexate. Case 2 She received a pulse of corticosteroids followed by a course of methotrexate. There was immediate improvement in her PIP joint swellings and within a few weeks she was able to walk without crutches for the first time in 6 months; a surveillance MRI confirmed complete radiographical resolution of myositis. Unfortunately, 18 months after her diagnosis, she had developed anterior uveitis of her left eye with posterior synechiae; this responded well to steroid and cyclopentolate eye drops. Case report - Key learning points We emphasise that clinicians should bear this rare differential diagnosis for in mind for consideration of early conservative management, assessment for uveitis, immunomodulation and possibly surgical correction to improve patient outcome.

scholarly journals Multi-Domain Touchscreen-Based Cognitive Assessment of C57BL/6J Female Mice Shows Whole-Body Exposure to 56Fe Particle Space Radiation in Maturity Improves Discrimination Learning Yet Impairs Stimulus-Response Rule-Based Habit Learning

2021 ◽  
Vol 15 ◽  
Author(s):  
Ivan Soler ◽  
Sanghee Yun ◽  
Ryan P. Reynolds ◽  
Cody W. Whoolery ◽  
Fionya H. Tran ◽  
...  
Keyword(s):  
Discrimination Learning ◽  
Space Radiation ◽  
Memory Systems ◽  
Whole Body ◽  
Cortical Function ◽  
Rule Based ◽  
Female Mice ◽  
Stimulus Response ◽  
Prefrontal Cortical ◽  
Response Rule

Astronauts during interplanetary missions will be exposed to galactic cosmic radiation, including charged particles like 56Fe. Most preclinical studies with mature, “astronaut-aged” rodents suggest space radiation diminishes performance in classical hippocampal- and prefrontal cortex-dependent tasks. However, a rodent cognitive touchscreen battery unexpectedly revealed 56Fe radiation improves the performance of C57BL/6J male mice in a hippocampal-dependent task (discrimination learning) without changing performance in a striatal-dependent task (rule-based learning). As there are conflicting results on whether the female rodent brain is preferentially injured by or resistant to charged particle exposure, and as the proportion of female vs. male astronauts is increasing, further study on how charged particles influence the touchscreen cognitive performance of female mice is warranted. We hypothesized that, similar to mature male mice, mature female C57BL/6J mice exposed to fractionated whole-body 56Fe irradiation (3 × 6.7cGy 56Fe over 5 days, 600 MeV/n) would improve performance vs. Sham conditions in touchscreen tasks relevant to hippocampal and prefrontal cortical function [e.g., location discrimination reversal (LDR) and extinction, respectively]. In LDR, 56Fe female mice more accurately discriminated two discrete conditioned stimuli relative to Sham mice, suggesting improved hippocampal function. However, 56Fe and Sham female mice acquired a new simple stimulus-response behavior and extinguished this acquired behavior at similar rates, suggesting similar prefrontal cortical function. Based on prior work on multiple memory systems, we next tested whether improved hippocampal-dependent function (discrimination learning) came at the expense of striatal stimulus-response rule-based habit learning (visuomotor conditional learning). Interestingly, 56Fe female mice took more days to reach criteria in this striatal-dependent rule-based test relative to Sham mice. Together, our data support the idea of competition between memory systems, as an 56Fe-induced decrease in striatal-based learning is associated with enhanced hippocampal-based learning. These data emphasize the power of using a touchscreen-based battery to advance our understanding of the effects of space radiation on mission critical cognitive function in females, and underscore the importance of preclinical space radiation risk studies measuring multiple cognitive processes, thereby preventing NASA’s risk assessments from being based on a single cognitive domain.

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