Search results for "dislocations"

Thermodynamics-based gradient plasticity theories with an application to interface models

2008

AbstractIn the framework of small deformations, the so-called residual-based gradient plasticity theory is reconsidered and improved. Using the notion of moving geometrically necessary dislocations (GNDs), suitable micromechanics interpretations are heuristically given for the higher order boundary conditions and the long distance particle interactions. Also, a comparison is made between this theory and the analogous virtual work principle (VWP)-based one, whereby their respective conceptual and methodological features are pointed out. The conditions under which the two theories lead to a same constitutive model are investigated, showing that, correspondingly, a certain indeterminacy exhibi…

Binocular motility system and temporomandibular joint internal derangement: A study in adults

2007

Abstract INTRODUCTION: Ocular convergence defects have been confirmed in adults with temporomandibular joint (TMJ) dysfunction, but few studies of the relationship of the oculomotor apparatus to TMJ disc displacement have been reported. The purpose of this study was to examine the impact of disc displacement on the oculomotor capacity of the eyes in adults. METHODS: Fifty symptomatic patients with bilateral TMJ disc displacement (13 men, 37 women; mean age, 28.84 +/- 8.22 years; range, 18-40 years) were compared with the same number of asymptomatic volunteers with normal disc position (14 men, 36 women; mean age, 29.96 +/- 5.04 years; range, 18-37 years). All subjects underwent standardized…

Temporomandibular chronic dislocation : the long-standing condition

2016

Background The temporomandibular joint (TMJ) dislocation can be categorised into three groups: acute, habitual or recurrent and long-standing. The long-standing or protracted lower jaw dislocation refers to a condition that persists for more than one month without reduction. There are a great variety of methods for its treatment, from the manual or non-surgical, to surgical ones like the indirect approach (conservative surgical approach) and direct approach (open joint). Additional procedures in unsuccessful cases may include extra-articular orthognathic techniques to correct a malocclusion until joint replacement. Material and Methods We report four new cases with a minimum of 6 weeks disl…

Is there a role for percutaneous pelvic and acetabular reconstruction?

2007

The primary goal in the treatment of pelvic fractures is the restoration of haemodynamic stability. The secondary goal is the reconstruction of stability and symmetry of the pelvic ring. Percutaneous reconstruction can only be accepted if these goals are met. The type of definitive surgery is dependent of the degree of instability of the anterior and posterior pelvic ring. Retrograde transpubic screw fixation of pubic rami fractures is a good alternative to external fixation or plate and screw osteosynthesis. The technique of screw placement and image intensifier control is explained. Internal fixation of pure sacroiliac dislocations, fracture-dislocations of the sacroiliac joint and sacral…

Trapping of hydrogen and helium at dislocations in tungsten: anab initiostudy

2017

Retention of plasma gas components such as hydrogen (H) isotopes and helium (He) is one of the limiting factors in selection of plasma facing materials for future thermonuclear fusion devices. Tungsten (W) is one of the promising candidates for such materials and was chosen for the divertor armor for International Thermonuclear Experimental Reactor (ITER) and the first wall material for the design of the demonstrational fusion power plant - DEMO. For the analytical estimation of accumulation of H/He components in tungsten, it is important to understand the relevant physical mechanisms of their trapping in the material and thoroughly parameterize them numerically. Experiments involving high …

Formation of dislocations in LiF irradiated with 3He and 4He ions

2018

Influence of the irradiation with 13.5 MeV 3He and 5 MeV 4He ions on the micro-structure and mechanical properties of LiF single crystals was studied. The depth profiles of nanoindentation, dislocation mobility, selective chemical etching and photoluminescence served for the characterization of damage. Strong ion-induced increase of hardness and decrease in dislocation mobility at the stage of track overlapping due to accumulation of dislocations and other extended defects was observed. At high fluences (1015 ions/cm2) the hardness saturates at about 3.5 GPa (twofold increase in comparison to a virgin crystal) thus confirming high efficiency of light projectiles in modifications of structur…

Atlantoaxial subluxation and congenital atlas arch defect

2014

Posterior subtalar dislocation.

2009

A subtalar dislocation of the foot is an uncommon injury, and cases of posterior subtalar dislocation are even rarer. This injury is characterized by a simultaneous dislocation of talocalcaneal and talonavicular joints while tibiotalar and calcaneocuboid articulations remain intact. Subtalar dislocation is commonly accompanied by fractures of the malleoli, talus, or fifth metatarsal and by a rotational component of the subtalar joint. Subtalar dislocation can occur in any direction and produces significant deformity. This article presents a case of pure posterior subtalar dislocation in an 80-year-old man who presented with pain and deformity in his left ankle following a motorcycle acciden…

Does clinical findings correlate with magnetic resonance imaging (MRI) findings in patients with temporomandibular joint (TMJ) pain? A cross sectiona…

2019

Background Although magnetic resonance imaging (MRI) helps to clearly visualize the disorders in temporomandibular joint (TMJ), the relationship between cross-sectional and clinical findings has not been precisely established. The aim of this study was to evaluate the relationship between clinical symptoms and MRI findings in individuals with TMJ pain. Material and Methods This cross-sectional study, conducted on the clinical and MRI findings of the patients, who applied to Uşak University, Oral and Maxillofacial Surgery Clinic with TMJ pain between the years 2016-2019. The primary predictor variables were MRI findings; disc position (normal, disc displacement with reduction (DDWR), disc di…

Transverse fracture-dislocation of the sacrum: a diagnostic pitfall and a surgical challenge.

2002

Transverse fracture-dislocations of the sacrum are rare. Associated lesions of the lumbosacral spine as well as neurological injuries are common. Conventional radiographs of the pelvis often fail to clearly visualize the fracture. Delayed diagnosis increases the risk of progressive neurological disfunction. True lateral sacral views and CT-scans with 3-dimensional reconstructions are very helpful in establishing the full extent of the injury. These examinations should be considered in all patients with a history of high energy trauma and clinical signs indicating lumbosacral injury, such as severe low back pain and neurological disturbances of the lower extremities. The management of transv…