Accuracy and interpretation of results from the DISA momentum flux meter

Summary The momentum flux apparatus was tested for accuracy in vitro. Errors were within an acceptable range for clinical evaluation and research of meatal properties in male patients — provided the stream exit angle was horizontal within 10–15 degrees. Measurements from the apparatus give information about the rigid nozzle or distensible meatus from which the stream is discharged. It is stressed, that great caution has to be exercised in the interpretation of the residual kinetic energy density and of the energy loss during micturition.     

The mandible,an overhanging mechanically suspended structure

Summary The mandible, owing to its form, surrounding muscles and position in the craniofacial unit can be assimilated to an overhanging mechanically suspended structure.The hypothesis, according to which the temporomandibular joints would be submitted to pressure during mastication should be abandoned on the basis of anatomical and clinical findings. Furthermore, this hypothesis is in disagreement with the results of simulation on a physicomathematical model of the mandible.Accordingly, it is reasonable to assume that the mandible is a suspended structure and that the elevator muscles of mastication, especially the masseter and medial pterygoid (together forming the mandibular sling), and probably also the anterior belly of the temporalis muscle play a twin role in the suspension of this bone. These muscles obviously command the movement of closure. They also constitute the suspensory apparatus of the mandible and, by mechanical computation, should display a certain degree of elasticity and undergo most of the mechanical constraints developed during mastication.One can also consider the cranio-facio-mandibulo-hyoid group as a suspended structure. The comparison of this type of system to the basic principles of servo-robotics allows to understand that such a structure is capable of extremely precise movements in all spatial planes with a minimum of effort.

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La mandibule, une structure suspendue mécaniquement en porte-á-faux. Réflexions sur le système d'appui et de servo-commandes de la mandibule

Résumé De par sa forme même, son environnement musculaire et sa situation dans l'ensemble cranio-facial, la mandibule peut être assimilée à une structure suspendue mécaniquement en porte à faux.L'hypothèse selon laquelle les articulations temporo-mandibulaires subissent des pressions au cours de la mastication doit être abandonnée pour des raisons anatomiques et cliniques. Elle est de plus infirmée par le calcul et les expériences de simulation sur modèle physico-mathématique.Il est donc logique d'admettre que la mandibule est une structure suspendue, et que les muscles manducateurs élévateurs, tout particulièrement les muscles masseter, ptérygoïdien médial (qui constituent la fronde mandibulaire) et probablement aussi le ventre antérieur du muscle temporal jouent un double rôle: ils commandent évidemment le mouvement de fermeture mais ils constituent aussi un dispositif de suspension de la mandibule devant par calcul présenter une certaine élasticité, et subissant l'essentiel des contraintes développées au cours de la mastication.On peut également considérer l'ensemble cranio-facio-mandibulo-hyoïdien lui-même comme une structure suspendue. La comparaison d'un tel type de système avec les principes utilisés en robotique asservie, permet de comprendre qu'un tel type de structure autorise une extrême précision des mouvements dans les trois plans de l'espace avec la mise en jeu d'efforts minimum.

     

An investigation of the effectiveness of Behavioral Momentum on the acquisition and fluency outcomes of tacts in three children with Autism Spectrum Disorder

The study aimed to evaluate the effectiveness of the fluency intervention, Behavioral Momentum (BM), on acquisition of tacts and associated fluency outcomes in three children with Autism Spectrum Disorder (ASD). A multiple probe design across stimulus sets was utilized to investigate the outcomes of Behavioral Momentum for the acquisition, retention, stability, endurance, and application of tacts learned to a fluency aim. In the intervention phase, children were required to complete a Behavioral Momentum exercise consisting of the presentation of a sequence of high probability tacts followed immediately by the presentation of low probability tacts delivered within 1 min timings. The results demonstrated positive fluency outcomes on low probability tacts across all children. The practical implications of the study are discussed in terms of the use of Fluency Training for children with ASD within the educational setting.     

On the physics of momentum in ballistics: Can the human body be displaced or knocked down by a small arms projectile?

Shooting incidents are often portrayed as resulting in a sometimes violent backwards displacement of the victim. This opinion is also not infrequently held by expert witnesses. The physical force responsible for this would be momentum (mass x velocity). The physics of momentum in ballistic injury is explained in detail. The maximum momentum transferred from different small arms projectiles including large calibre rifles and a 12-gauge shotgun only results in a backwards motion of a 80 kg target body of 0.01–0.18 m/s, which is negligible compared to the velocity of a pedestrian (1–2 m/s). Furthermore, counterbalance is constantly maintained by neurophysiological reflexes. So the effect of the momentum transferred from the missile is virtually zero and there is no backwards motion of the person shot. Empirical evidence verifying these calculations can be obtained from hunting big game, from human gunshot victims and from a video documentary demonstrating the lack of any backwards motion of a person wearing body armour after hits from a centre fire rifle. So the alleged backwards hurling of a person shot is nothing but a myth which should be refuted not only because it is incorrect but also because it can result in miscarriages of justice.     

Velocity measurements within confined turbulent jets: Application to cardiovalvular regurgitation

An expression for centerline mean velocity distributions for circular and noncircular confined turbulent jets has been obtained by assuming self-preservation of flow downstream of the jet potential core. It was assumed that the velocity decay was not only dependent on the streamwise distancex in terms ofx/d, as in the case of free jets, but also on the ratio of the orifice diameterd to the confining pipe diameterD. To validate the expression and to determine the empirical constants, measurements of the centerline velocities within the confined jets issuing from different size circular orifices and various noncircular orifices of different shapes were conducted. The results indicate that the validity of the expression is restricted tod/D≤0.25 and is weakly dependent on the particular orifice shape. It is suggested that, as for the case of free turbulent jets reported earlier, that this expression may be used potentially to predict the valvular lesion size or to estimate the volume of valvular regurgitation for confined jets provided the value ofD, which corresponds to the “atrial diameter”, is known or statistically available.     

Clinical applications of momentum flux measurements with special reference to detrusor hyperreflexia and meatal stenosis

Summary Distensibility of the meatal part of urethra was studied in 67 patients with detrusor hyperreflexia and in 7 patients with organic meatal stenosis using the momentum flux meter. Statistically significantly higher momentum flux values were found in patients with non obstructive detrusor hyperreflexia compared to normal persons-indicating a tighter meatus than normal. The connection between tight meatus and detrusor hyperreflexia is discussed. Also in patients with organic meatal stenosis momentum flux measurements showed a rigid meatus. Because of its high diagnostic specificity, momentum flux measurement may prove valuable as a screening investigation in male patients with suspected detrusor hyperreflexia or distal urethral stenosis.     

Movement analysis of sit-to-stand – research informing clinical practice

Abstract

Background:

Sit-to-stand (STS) is a crucial transfer influencing a person's independence in daily activities, as well as safety and quality of life, and is thus vital to evaluate in research and in practice. Clinical STS tests provide single values in seconds or numbers of STS. There is, however, increasing numbers of research papers reporting spatial and temporal kinematic and kinetic process STS data.

Objectives:

To provide an overview of research findings from laboratory-based movement analyses regarding phases and determinants of typical STS, characteristics of successful versus failed STS transfers, and finally STS performance in some neurological conditions.

Major Findings:

The STS transfer, previously regarded as mainly requiring lower limb muscle strength, is increasingly recognized as a complex transfer skill. Muscle strength, balance, foot position, chair height and the movement strategy are major determinants influencing STS performance. Scaling and timing of momentum generation throughout STS seems critical for success or failure. Sit-to-stand in stroke and Parkinson's disease (PD) is characterized by asymmetry in force generation and difficulties in switching movement direction, respectively. In-depth, knowledge regarding mechanisms of momentum control during STS sub-phases, STS failures, as well as exploration of variability in normal and atypical STS is still lacking.

Conclusions:

Recent research based on instrumented movement analyses has generated better understanding of movement control during STS, but the specifics are not yet reflected in clinical assessments. There seems to be a call for clinical tools capturing determinants and process characteristics of the STS transfer for a more comprehensive evaluation in rehabilitation.     

The Value of Integrating Policy People and Space in Research

In this article, we address several tangible and intangible factors, which are difficult to quantify and often overlooked yet are crucial for research success. We discuss three dimensions which encompass: (1) policy, (2) people, and (3) space. Policies, such as rules and regulations, define the culture of any research program/initiative. Governing rules and regulations defined within these policies are dictated by cultural values. Individuals who exhibit strong leadership, promote innovation, and exercise strategic planning often determine the governing policies. People are the most valuable asset available to any institution. Ensuring the professional growth (personal and scientific) and creating an environment which supports collaborative and collegial research through teamwork are factors that are important for individuals. Space, the physical work environment, is the third dimension of our model and is often an underutilized resource. In addition to the physical layout and design of the space, creating a positive work atmosphere which supports research initiatives is equally important and can create valuable momentum to research efforts. Collectively, these three dimensions (policy, people, and space) have a significant impact on the success of any research initiative. The primary objective of this article is to create awareness and emphasize the importance of implementing these variables within research initiatives in academic settings.