Search results for "Axia"

Analytical approach for the problems of dynamics and stability of a moving web

2015

Problems of dynamics and stability of a moving web, modelled as an elastic rod or string, and axially travelling between rollers (supports) at a constant velocity, are studied using analytical approaches. Transverse, longitudinal and torsional vibrations of the moving web are described by a hyperbolic second-order partial differential equation, corresponding to the string and rod models. It is shown that in the framework of a quasi-static eigenvalue analysis, for these models, the critical point cannot be unstable. The critical velocities of one-dimensional webs, and the arising non-trivial solution of free vibrations, are studied analytically. The dynamical analysis is then extended into t…

Efectos de la vibración sobre la actividad del rectus abdominis y sobre la transmisión de aceleraciones durante la realización de un puente frontal. …

2012

Durante las dos ultimas decadas se ha incrementado notablemente la utilizacion de la vibracion como medio complementario de ejercicio fisico. La literatura cientifica muestra distintos efectos positivos, aunque la mayor parte de ensayos se han centrado en el analisis del ejercicio de squat. El objetivo del presente estudio fue analizar la actividad muscular del rectus abdominis y la transmision de la vibracion en el cuerpo humano durante la realizacion de un puente frontal sobre una plataforma vibratoria oscilante vibrando a diferentes frecuencias (5, 16, 20 Hz) y a una amplitud constante (3 mm). Las aceleraciones maximas en la cabeza (ejes X, Y, Z) y la actividad electromiografica media de…

On the limit velocity and buckling phenomena of axially moving orthotropic membranes and plates

2011

In this paper, we consider the static stability problems of axially moving orthotropic membranes and plates. The study is motivated by paper production processes, as paper has a fiber structure which can be described as orthotropic on the macroscopic level. The moving web is modeled as an axially moving orthotropic plate. The original dynamic plate problem is reduced to a two-dimensional spectral problem for static stability analysis, and solved using analytical techniques. As a result, the minimal eigenvalue and the corresponding buckling mode are found. It is observed that the buckling mode has a shape localized in the regions close to the free boundaries. The localization effect is demon…

Ultrasound measurements in bone using an array transducer

2014

Analysis of stability of axially moving orthotropic membranes and plates with a linear non-homogeneous tension profile

2011

A Critical Review of Alien Limb-Related Phenomena and Implications for Functional Magnetic Resonance Imaging Studies

2021

Consensus criteria on corticobasal degeneration (CBD) include alien limb (AL) phenomena. However, the gist of the behavioral features of AL is still “a matter of debate.” CBD-related AL has so far included the description of involuntary movements, frontal release phenomena (frontal AL), or asomatognosia (posterior or “real” AL). In this context, the most frequent symptoms are language and praxis deficits and cortical sensory misperception. However, asomatognosia requires, by definition, intact perception and cognition. Thus, to make a proper diagnosis of AL in the context of CBD, cognitive and language dysfunctions must be carefully verified and objectively assessed. We reviewed the current…

Walk the Line. The Surgical Highways to the Craniovertebral Junction in Endoscopic Approaches: A Historical Perspective

2018

Background We compiled a comprehensive literature review on the anatomic and clinical results of endoscopic approaches to the craniocervical junction (CVJ) to better contribute to identify the best strategy. Methods An updated literature review was performed in the PubMed, OVID, and Google Scholar medical databases, using the terms “Craniovertebral junction,” “Transoral approach,” “Transnasal approach,” “Transcervical approach,” “Endoscopic endonasal approach,” “Endoscopic transoral approach,” “Endoscopic transcervical approach.” Clinical series, anatomic studies, and comparative studies were reviewed. Results Pure endonasal and cervical endoscopic approaches still have some disadvantages, …

Craniopharyngiomas in Children - Experience of Consecutive 152 Operated Cases

2020

Context Craniopharyngiomas (CPH) are benign tumors, rarely encountered in children, representing 5-6% of all intracranial tumors. Objective This study aimed to analyze the surgical management and quality of life in a series of CPH pediatric cases. Design This was a multicenter study performed over a 25-year period (1994 - 2019) in Bucharest. Subjects and methods 152 children (0-17 years old) were treated for CPH. Preoperative manifestations were intracranial hypertension, endocrine dysfunction, visual impairment, ataxia, intellectual performance decrease. Results Considering all surgical approaches used, we advocate for pterional approach to best fit in CPH. We achieved gross-total removal …

Could thiazolidinediones increase the risk of heart failure in Friedreich's ataxia patients?

2011

Clinical evidence and the recent decisions of the European Medicines Agency and the Food and Drug Administration challenge the safety of thiazolidinediones treatment. Recently, this treatment has been suggested for Friedreich's ataxia because thiazolidinediones improve neurological symptoms. Hypertrophic cardiomyopathy is the most prevalent cardiac feature and the cause of premature death in Friedreich's ataxia patients. We recommend that therapy with peroxisome proliferator-activated receptor-gamma agonists like thiazolidinediones be taken with caution, as they cause a decrease in the number of fast fibers and an increase in mitochondrial biogenesis in cardiac muscle because of the inducti…

Ocular motor biomarkers in Niemann-Pick disease type C: A prospective cross-sectional multicontinental study in 72 patients

2020

AbstractNiemann-Pick type C (NPC) is a rare lysosomal storage disorder with ocular motor involvement. In a multicontinental, cross-sectional study we characterized ocular motor function in 72 genetically proven patients from twelve countries by means of video-oculography. Interlinking with disease severity, we also searched for ocular motor biomarkers. Our study protocol comprised reflexive and self-paced saccades, smooth pursuit, and gaze-holding in horizontal and vertical planes. Data were compared with those of 158 healthy controls. The Modified Disability Rating Scale, Scale for Assessment and Rating of Ataxia, Spinocerebellar Ataxia Functional Index for neurological status, and Montrea…