Criteria For Displacement Research Articles

EXPERIENCE OF CLINICAL AND RADIOGRAPHIC CORRELATION IN PATIENTS WITH PAIN SYNDROME OF TMJ DYSFUNCTION IN ATRICULATION-OCCLUSIVE DISORDERS

This article examines the imaging anatomy of the temporomandibular joint (TMJ), describes the technique of calculating the gaps between the fossa and the head, their comparison based on TMJ computed tomography (CT) data, and their comparison with clinical signs of TMJ dysfunction. The aim was to determine CT diagnostic criteria for persistent functional displacement of the lower jaw in patients with TMJ functional disorders in occlusal-articulation disorders at the stage of orthopedic treatment planning. Research materials and methods. A clinical and radiological examination of 150 patients with functional disorders of the masticatory apparatus and occlusal disorders, who were included in the experimental group, and 30 practically healthy persons – the control group, was carried out. The results. The presence of a pain syndrome was primarily determined - 60 patients (40.00%) complained of pain in the TMJ area, masticatory muscles or headache, and in 19 (31.67%) of them, complaints of pain bothered more than half year TMJ pain was found in 30 (20.00%) patients, in masticatory muscles in 43 (28.67%), headache in 47 (31.33%). Hypertonus of the masticatory muscles was established - 94 - 62.67% with their hypertrophy - 46 - 30.67%, both unilateral and bilateral, which were observed simultaneously with the parafunction of the masticatory muscles (34 - 22.67%). Palpatory functional stable displacement of the lower jaw was determined in 135 (90.00%) patients of the research group, in 57 (42.22%) of them significant pain syndrome was present in 46 (80.70%). At the same time, deviation or deflexion was established in 74 (49.33%) patients of the experimental group, restriction of mouth opening in 52 (32.67%) patients; crunching and clicking in the TMJ - 112- 74.67%. The presence of bilateral posterior displacement of the heads of the lower jaw was established in 103 (68.67%) patients with TMJ dysfunction, of which 42 (40.77%) came to the doctor with complaints of orofacial pain, and in 22 (14.67%) significant displacement, 17 (77.27%) of them had a pain syndrome; unilateral posterior displacement of the heads of the lower jaw in 32 (21.33%) patients with TMJ dysfunction, 16 (50.00%) of them have a pain syndrome, and 11 of them have a significant displacement; in 16 (10.67%) one-sided posterior displacement with simultaneous anterior displacement in the contralateral joint was established with a subjective assessment of the absence of pain syndrome. Presence of a significant displacement in at least one joint was established in 72 (48.00%) patients with TMJ dysfunction, 63 (87.50%) of them had a pain syndrome. Conclusions. CT enables a comprehensive assessment of bone structures and their connection in the TMJ and is a valuable tool for planning orthopedic treatment and evaluating its effectiveness in dynamics.

Flexible Intramedullary Nail Placement in Pediatric Humerus Fractures.

Flexible intramedullary nailing is an effective method of stabilization in pediatric patients with a humeral shaft fracture when surgery is indicated1-3. Although these fractures are most often treated nonoperatively, operative indications include open fractures, bilateral injuries, compartment syndrome, pathologic fractures, neurovascular compromise, unacceptable alignment after attempted nonoperative treatment, and ipsilateral upper-extremity injuries4. The current literature on flexible intramedullary nailing of the pediatric humeral shaft lacks concise descriptions of available entry points, which directly affect the subsequent technique, and of pertinent pediatric-specific anatomy. Thus, the present article focuses on these entry points in the pediatric patient. Various entry points are available for the insertion of flexible nails into the humeral shaft. A surgeon must initially decide whether the patient and fracture characteristics are best suited for anterograde versus retrograde insertion. This choice typically depends on several fracture and patient-related characteristics. The passage of flexible intramedullary nails has been well described; thus, the present article will place special emphasis on the available proximal and distal entry points and pediatric-specific anatomy5-10. For diaphyseal fractures, we prefer dual distal lateral entry points with the nails advanced retrograde in a C-S configuration whenever possible, given the risks associated with proximal lateral entry (e.g., damage to the axillary nerve) or distal medial entry (e.g., damage to the ulnar nerve or nail prominence). A distal posterior supracondylar entry point is also possible but requires additional preoperative planning with regard to patient positioning, a more proximal entry point to avoid impingement of the olecranon on the nail in extension, and avoidance of the ulnar nerve. The substantial potential for remodeling in pediatric patients permits nonoperative treatment of humeral fractures if specific age-related criteria for angulation and displacement are met. Generally accepted tolerances for nonoperative angulation and displacement are as follows: for patients <5 years old, ≤70° angulation and up to 100% displacement; for patients 5 to 12 years old, 40° to 70° angulation; and for patients >12 years old, ≤40° angulation and 50% apposition4. The use of flexible nails is often preferred because of the healing potential of pediatric humeral shaft fractures, the ability of flexible nails to tolerate nonrigid fixation until osseous bridging occurs, the ability of the surgeon to avoid exposure of neurologic structures during surgery, and the benefit of avoiding physeal disruption. These factors make flexible nails a favorable option when compared with plate osteosynthesis or rigid intramedullary nailing. When indicated, the use of flexible intramedullary nails in pediatric humeral fractures has been associated with high rates of union, good functional outcomes, early range of motion, and an acceptably low rate of complications2. Be familiar with the technical details associated with all available entry points.Avoid damage to key neurologic structures around the proximal and distal humerus.Minimize the opportunity for symptomatic hardware.Optimize the biomechanics through flexible nail positioning at the fracture site. FIN = flexible intramedullary nailingEBL = estimated blood lossf/u = follow-upIM = intramedullaryMRI = magnetic resonance imagingOR = operating roomPT = physical therapyROM = range of motion.

A study on the functional and radiological outcome with complications in the management of proximal humerus fractures operated with proximal humerus internal locking osteosynthesis system

Background: A number of opinions exist regarding the management of proximal humerus fractures starting from conservative to tension band-wiring to internal fixation with plates. The aim of this study is to assess the functional outcome, the radiological outcome and the complications associated with the management of proximal humerus fractures treated with proximal humerus interlocking osteosynthesis system (PHILOS). Methods: A prospective descriptive study was undertaken comprising of 40 patients. Closed proximal humerus fractures meeting Neer’s criteria for operative displacement were enrolled. Patients underwent open reduction internal fixation with PHILOS plate. Post-operative radiological outcome was estimated with follow-up x-rays, functional outcome using the Constant and Murley score. Results: 60% patients were female, with the most common mode of injury being fall at a ground level. Late complications were noted in 25% of patients, which were malunion 5%, joint stiffness 10%, joint instability 5% and heterotopic ossification 5%. The mean Constant and Murley score was 79.5 and it was found to be statistically significant to the type of fracture according to the Neer’s classification (Kruskal Wallis test, p=0.005). Joint stiffness was also found to be statistically significantly correlated to the type of fracture pattern (Chi square test, p=0.016). The average time to union was 10 weeks. Conclusions: Thus, by this study it can be expressed due to appropriate articular reduction by open reduction and by the use of a fixed angle implant like the PHILOS plate, operative management of proximal humerus fractures by the said implant is a viable option to enable quick and early rehabilitation of patients.

Surgical and non-operative management of displaced scapular fractures and long-term outcomes

Abstract Objective To compare the long-term functional outcome of surgically and non-operatively managed patients with displaced intra- and extra-articular scapular fractures. Methods This study included patients with intra- and extra-articular scapula fractures, treated between 2010 and 2020 in a Swiss level 1 trauma centre. The decision to operate was based on standardized criteria for fracture displacement. Patients with isolated Bankart lesions (Ideberg 1) and process fractures (AO type 14-A) were excluded. Primary outcomes were functional patient reported measures (DASH score) and quality of life (EQ5D score). Secondary outcomes were complications, radiological union, satisfaction with treatment, pain and range of motion. Results Out of 486 cases, 74 patients had displaced scapula fractures. Forty patients were treated surgically and 34 were treated conservatively. Significantly more patients with intra-articular fractures and high-energy trauma were treated surgically. Fifty percent returned the questionnaires after a mean follow-up of 47 months (± SD 36). The mean DASH score of this group was 12 (SD 15.6), with a mean of 14.7 (SD 15.9) in the surgery group and 9.8 (SD 14.6) in the non-operative group (p = 0.7). Multivariate analysis did not show statistically significant correlating factors. No significant differences in quality of life were observed. Patients rated their treatment with a mean of 8.6/10 (SD 1.8). Among surgically treated patients, 19 underwent a deltoid sparing procedure with significant shorter time to union than those that underwent deltoid release (23 vs. 49 weeks, p&amp;lt;0.01). Complications occurred in 3/28 surgically treated patients and all three required a reoperation. Conclusion Functional results after conservative and surgical treatment were similar, despite more complex fractures and more intra-articular fractures being treated surgically. Osteosynthesis of both intra- and extra-articular scapula fractures is safe and leads to good functional results, furthermore, new minimal invasive techniques may lead to faster bone healing and return to work and sports.

Long-term follow-up of patients with displaced scapular fractures managed surgically and non-operatively

IntroductionControversy remains on which patients with displaced scapula fractures benefit from surgery. This retrospective cohort study aims to compare and describe long-term patient-reported outcomes of patients with displaced scapula fractures treated both surgically and conservatively. MethodsThis study included patients with intra- and extra-articular scapula fractures, treated between 2010 and 2020 in a Swiss level 1 trauma centre. The decision to operate was based on standardized criteria for fracture displacement. Patients with isolated Bankart lesions (Ideberg 1) and process fractures (AO type 14-A) were excluded. Primary outcomes were functional patient reported measures (DASH score) and quality of life (EQ5D score). Secondary outcomes were complications, radiological union, satisfaction with treatment, pain and range of motion. ResultsOut of 486 cases, 74 patients had displaced scapula fractures. Forty patients were treated surgically and 34 were treated conservatively. Significantly more patients with intra-articular fractures and high-energy trauma were treated surgically. Fifty percent returned the questionnaires after a mean follow-up of 47 months (± SD 36). The mean DASH score of this group was 12 (SD 15.6), with a mean of 14.7 (SD 15.9) in the surgery group and 9.8 (SD 14.6) in the non-operative group (p = 0.7). Multivariate analysis did not show statistically significant correlating factors. No significant differences in quality of life were observed. Patients rated their treatment with a mean of 8.6/10 (SD 1.8). Among surgically treated patients, 19 underwent a deltoid sparing procedure with significant shorter time to union than those that underwent deltoid release (23 vs. 49 weeks, p<0.01). Complications occurred in 3/28 surgically treated patients and all three required a reoperation. ConclusionIn this cohort, functional results after conservative and surgical treatment were similar, despite more complex fractures and more intra-articular fractures being treated surgically. Osteosynthesis of both intra- and extra-articular scapula fractures is safe and leads to good functional results, furthermore, new minimal invasive techniques may lead to faster bone healing and return to work and sports

Temporomandibular Joint Anterior Disc Displacement Without Reduction

A 31-year-old woman was referred to physical therapy by her dentist for sharp pain in the right temporomandibular joint (TMJ) area. A week following the physical therapy examination, the magnetic resonance imaging previously ordered by the dentist was performed. The imaging and clinical findings met the diagnostic criteria for right anterior disc displacement without reduction and with limited mouth opening. JOSPT Cases 2021;1(4):287–288. doi:10.2519/josptcases.2021.10555

ЛУЧЕВАЯ ДИАГНОСТИКА ПРИ ЛЕЧЕНИИ СМЕЩЕНИЯ СУСТАВНОГО ДИСКА ВИСОЧНО-НИЖНЕЧЕЛЮСТНОГО СУСТАВА И МИОФАСЦИАЛЬНЫХ РАССТРОЙСТВ

Purpose: Determination of the volume and sequence of radiation studies in the treatment of patients with displacement of the articular disc of the temporomandibular joint (TMJ)and myofascial pain disorders.&#x0D; Material and methods: The study included 48 patients with displacement of the articular disc of the TMJ and myofascial pain disorders. Clinical criteria for articular displacement were confirmed by MRI and CBCT. Studies of the function of the masticatory muscles were carried out at the Synapsis electromyograph. All patients underwent complex treatment, including relaxation of the masticatory muscles and relief of pain using injections of botulinum toxin in the actual masticatory, temporal and lateral pterygoid muscles (LPM), followed by repositioning split therapy. For the introduction of muscle relaxant in LPM, we have developed and applied external periarticular injection access to LPM. The method is based on reaching the zone of joint attachment of the upper and lower heads of the LPM with MRI navigation. Surveillance continued for up to 12 months with MRI monitoring of the position of the articular disc.&#x0D; Results: The stages of treatment of SJS of the TMJ with control use of MRI and CT, as well as a method for the administration of botulinum toxin under MRI navigation, have been developed. The first stage included CT and MRI of the temporomandibular joint, the second stage – injections of botulinum toxin into the masticatory muscles using the developed periarticular access to the LPM with MRI navigation, as well as CBCT with a splint to control the new (established) position of the lower jaw; the third and fourth stages included continuation of the reduction splint therapy, correction of the splint, observation for 3-6 months with control CBCT after 6 months to assess the position of the mandible without splint. Achieved an increase in the posterior and upper temporomandibular joint distances and the correct position of the lower jaw.&#x0D; Conclusion: Performing radiation studies on time at certain stages of treatment, differing in their content and volume, provided a complete diagnosis, planning treatment measures and monitoring the results.

Ecological Character Displacement in Non-Congeneric Frogs.

Character displacement is phenotypic divergence driven by competition (ecological character displacement) or reproductive interference (reproductive character displacement). Although previous studies have examined these phenomena separately, recent evidence suggests that reproductive interference can drive both reproductive and ecological character displacement, in that certain traits are related to both competition and reproduction. Thus, to evaluate the effect of competition, the effect of reproductive interference must be excluded. Here, we analysed ecological character displacement between non-congeneric frogs, which show little reproductive interference. Odorrana amamiensis inhabits the Amami and Tokunoshima Islands, Japan, whereas its non-congeneric competitor Babina subaspera inhabits the Amami Island. We tested three of the Schluter (2000) criteria for ecological character displacement: phenotypic changes in O. amamiensis between the two islands, phenotypic change related to prey preference, prey availability between the two islands. We demonstrated that the three criteria in Schluter (2000) were likely to be satisfied, indicating the occurrence of ecological character displacement in non-congeners without reproductive interference. Thus, we conclude that competition is potentially the main driver of this phenotypic divergence, and that non-congeners may be a suitable model for evaluating ecological character displacement in a variety of organisms, as the influence of reproductive interference can be excluded.

Comparative evaluation of three gingival displacement materials for efficacy in tissue management and dimensional accuracy.

Aim:Displacement of gingiva is essential for obtaining accurate impressions for the fabrication of fixed prostheses, particularly when the finish line is at or within the gingival sulcus. Various newer impression materials have been introduced to achieve gingival displacement while recording the impressions. A comparative evaluation of these new gingival displacement materials was deemed necessary for efficacy in tissue management and dimensional accuracy.Materials and Methods:Ten individuals were selected according to the inclusion and exclusion criteria for gingival displacement using retraction cord impregnated with aluminum chloride and two polyvinyl siloxane impression materials (Aquasil and NoCord VPS impression system) according to Latin block design. Intraoral scanner and Vernier caliper were used to study and compare the dimensional accuracy of each die obtained following which the dies were sectioned and evaluated under optical microscope with image analyzer to measure the amount of gingival retraction.Results and Conclusion:Statistical analysis showed that the amount of gingival retraction obtained by using retraction cord impregnated with aluminum chloride as gingival retraction agent was maximum as compared to NoCord followed by Aquasil. All three gingival displacement techniques could produce gingival displacement >0.2 mm which is the optimum amount of retraction required for impression making. All the three materials are found to be dimensionally accurate.

A prospective study on functional and radiological outcome of proximal humeral fractures treated with locking compression plates

Fractures of proximal humerus account for about 4 to 5% of all fractures. It is the third most common fracture after hip fracture and colles fracture in elderly patients. In this study we have analysed 20 cases of proximal humeral fractures treated surgically using (PHILOS) proximal humerus locking compression plates admitted at Department of Orthopaedics and Traumatology, Government Kilpauk Medical College and Hospital, Chennai from April 2013 to November 2013. The aim of the study was to analyze the functional and radiological outcome and to assess the complications of proximal humeral fractures treated using locking compression plates. Patients with proximal humerus fractures, who are skeletally mature and age more than 18 years satisfying Neer s criteria for operative displacement were selected. The patients were operated by the standard anterior deltopectoral approach or deltoid splitting approach using proximal humerus locking plates. All the patients were reviewed at two weeks interval, for first three months and later every month, Radiological evaluation of fracture union was observed by serial X rays. Constant and Murley’s score was used to assess the functional outcome of our patients. The average constant score in our study with 20 patients was 82.4. Finally we concluded that displaced proximal humeral fractures when treated surgically produce greater range of movements (ROM), less pain and less stiffness.

Outcomes of Pediatric Fractures Managed With Closed Reduction by Orthopaedic Residents in the Emergency Department.

Closed reduction of pediatric fractures is commonly performed by orthopaedic residents using conscious sedation in the emergency department (ED). The purpose of this study was to determine the rate of satisfactory reductions as performed by residents, and to determine the outcomes of these procedures. A retrospective review was performed of all fractures that underwent closed reduction under conscious sedation in the ED of a level 1 pediatric trauma center between January 1, 2010 and November 30, 2014. Initial and subsequent radiographs were reviewed and a determination was made as to whether the initial reduction was satisfactory, based on predetermined criteria for angulation and displacement. If a second reduction attempt in the operating room was necessary, this was noted. Chart notes were reviewed until a documented endpoint was reached, such as uneventful healing, malunion, nonunion, or growth arrest. A total of 838 subjects were identified. The upper extremity was involved in 85% of the fractures. Of the initial 838 fracture reductions performed, 39 (4.7%) were unsatisfactory. Residents on their first pediatric orthopaedic rotation had a higher unsatisfactory reduction rate compared with more experienced residents (7.0% vs. 3.4%, P=0.01). A second reduction was performed for 94 of 749 (12.6%) fractures. Of these, 35 (37.2%) required an open procedure to accomplish a satisfactory reduction. Fractures with initially satisfactory reductions were significantly less likely to require a second reduction attempt than those with initially unsatisfactory reductions (9.2% vs. 80.0%, P<0.01). The likelihood of a satisfactory reduction was significantly higher in the upper extremity than in the lower extremity. Overall, the vast majority (99.2%) of fractures had a satisfactory final outcome. Most attempts at closed reduction of pediatric fractures in the ED by orthopaedic residents are successful, and the likelihood of a satisfactory reduction was associated with increased levels of resident experience. Fractures with an initially successful reduction were far less likely to require remanipulation. Level IV-this is a therapeutic case series.

Distal Radius Fractures Do Not Displace following Splint or Cast Removal in the Acute, Postreduction Period: A Prospective, Observational Study.

Background Displacement of distal radius fractures has been previously described in the literature; however, little is known about fracture displacement following splint or cast removal at the initial clinic visit following reduction and immobilization. Purpose The purpose of this study was to evaluate risk factors for fracture displacement following splint or cast removal and physical examination in the acute postinjury period. Methods All patients with a closed distal radius fracture who presented to our orthopedic hand clinic within 3 weeks of injury were prospectively enrolled in our study. Standard wrist radiographs were obtained prior to splint or cast removal. A second wrist series was obtained following physical exam and application of immobilization at the end of the clinic visit. Radiographic parameters for displacement were measured by two independent reviewers and included dorsal angulation, radial inclination, articular step-off, radial height, and ulnar variance. Displacement was assessed using predefined, radiographic criteria for displacement. Results A total of 64 consecutive patients were enrolled over a period of 12 weeks. Of these, 37.5% were classified as operative according to American Academy of Orthopaedic Surgeons guidelines and 37.5% met LaFontaine instability criteria. For each fracture, none of the five measurements exceeded the predefined clinically or statistically significant criteria for displacement. Conclusion Splint removal in the acute postinjury period did not result in distal radius fracture displacement. Clinicians should feel comfortable removing splints and examining underlying soft tissue in the acute setting for patients with distal radius fractures after closed reduction. Level of Evidence Level II, prospective comparative study.

In-the-plane design of an off-axis ophthalmic adaptive optics system using toroidal mirrors

Adaptive optics (AO) ophthalmoscopes have garnered increased clinical and scientific use for imaging the microscopic retina. Unlike conventional ophthalmoscopes, however, AO systems are commonly designed with spherical mirrors that must be used off-axis. This arrangement causes astigmatism to accumulate at the retina and pupil conjugate planes, degrading AO performance. To mitigate this effect and more fully tap the benefit of AO, we investigated a novel solution based on toroidal mirrors. Derived 2(nd) order analytic solutions along with commercial ray tracing predict performance benefit of toroidal mirrors for ophthalmoscopic use. For the Indiana AO ophthalmoscope, a minimum of three toroids is required to achieve performance criteria for retinal image quality, beam displacement, and beam ellipticity. Measurements with fabricated toroids and retinal imaging on subjects substantiate the theoretical predictions. Comparison to off-the-plane method is also presented.

Extreme Modal Combinations for Pushover Analysis of RC Buildings

The pushover method is a practical procedure for comprehensive nonlinear analysis of structures subjected to seismic action. Application of this method, in accordance with the Eurocode 8 rules and due to engineering simplicity, favours application utilizing the first mode. The aim of the presented research in this paper was to find the influence of multi modal combinations in assessing the bearing capacity of reinforced concrete (RC) frames and walls. This paper presents a procedure in which the most extreme state is defined by the lowest ground acceleration caused by a predetermined shape of an elastic spectrum. The extreme bearing value is obtained by the envelope principle. Mode shapes and period sizes are determined on a linear elastic model while the limit state of the load bearing system is evaluated in a nonlinear state of structures. Results of the analysis show that influences of higher modes are significantly higher and that the safety/reliability, indicated by the criteria for the target displacement, in accordance with Eurocode 8 (Annex B), is not achieved. Inclusion of higher modes, in some presented examples, decreases the peak ground acceleration by more than two times, which is significantly less favourable than the target displacement criteria.

Analysis of Criteria for MRI Diagnosis of TMJ Disc Displacement and Arthralgia.

Aims. To improve diagnostic criteria for TMJ disc displacement (DD). Methods. The standard protocol for MRI diagnosis of DD, using a 12 o'clock reference position, was compared to an alternative protocol. The alternative protocol involves the functional relationship between the condyle and articular eminence, using a line perpendicular to the posterior slope of the eminence as a reference for disc position. The disc location was examined using both protocols, and disc diagnoses were compared in their relationship with joint pain. Statistical analyses included P value, sensitivity, specificity, odds ratio, and kappa statistic. Results. 58 MRIs were interpreted. 36 subjects reported arthralgia; 22 did not. Both protocols demonstrated significance (standard P = 0.004, alternative P < 0.001) for the ability to predict arthralgia. The odds of arthralgia increased in DD patients diagnosed by standard methods 9.71 times and in DD diagnosed by alternative means 37.15 times. The diagnostic sensitivity decreased 30% using the alternative versus the standard protocol (0.6389 versus 0.9444), while specificity increased 60% (0.9545 versus 0.3636). Conclusions. A stronger relationship occurs between DD and arthralgia when using a function-based protocol. The alternative protocol correctly identifies subjects without arthralgia, who by standard methods would be diagnosed with DD, as having nondisplaced discs, providing a more clinically relevant assessment of TMJ disc displacement.

High Displacement Glass Seismic Systems

The intent of this technical paper is to present and document the seismic performance of three new structural glass systems, each of which was designed to accommodate the elastic and inelastic seismic displacement criteria for high displacement in areas with high seismic activity. These systems include a rail-supported seismic glazing system, a point-fixed seismic glazing system, and a point-fixed seismic fin glass system. These systems may be used for cladding facades of buildings in areas of high seismicity and in particular in the state of California Seismic Zone 4. The California Building Code is now the underlying design methodology for the design of building cladding systems in California As most point supported glazing systems that are commonly used are not able to accommodate large building drifts, there was a need for an alternate point supported cladding system to address the design criteria imposed by current building codes. The performance of these systems was verified by mock-up testing, demonstrating that the proposed glazing systems can be used for cladding facades of building structures in areas of high seismicity, such as the state of California. The mock-up testing verified that the glass would translate horizontally and distribute seismic drift evenly over the height of the glazing systems, without breaking any components or glass. The testing also demonstrated that the silicone would withstand the shear demand imposed without rupturing the seal. The authors of this paper contributed to these three new glazing systems in ways of system engineering, design development, component finite analysis, preparation of engineering reports, test procedures, mock-up test result analysis, and project management for the actual implementation on the three successful installations. After successful completion of the mock-up test structures, each of these individual systems was used in real project applications; these projects are currently completed with the glazing systems fully installed. Please refer to the actual technical paper for detailed analysis on these systems.

The wind‐induced response characteristics of atypical tall buildings

AbstractA tall building reacts sensitively to winds because the wind force increases according to the height and shape of the building. Various shapes of tall buildings and their aerodynamic characteristics have been studied extensively. For structural design and occupant comfort, the dynamic displacement of a tall building must be maintained within the criteria for acceptable levels of wind‐induced motion. An aerodynamically appropriate building shape needs to be selected at the design stage of a tall building. In this study, wind‐induced vibration responses were investigated, according to the criteria for maximum acceptable displacement and acceleration. Copyright © 2007 John Wiley &amp; Sons, Ltd.

MRI of radial displacement of the meniscus in the knee

Objective To describe the phenomenon of radial displacement of the meniscus of the knees in the study population with MR imaging, and to establish MRI diagnostic criteria for radial displacement of the meniscus and displacement index.Methods MR signs of radial displacement of the meniscus were evaluated retrospectively in 398 patients with knee symptoms who were examined with non-weight bearing MR images from Jan. 2000 to Feb. 2004. The patients younger than 18 years old, with joint effusion or serious arthropathy were excluded and 312 patients were eligible to be enrolled in this study. The criterion for radial displacement of the meniscus was defined as the location of the edge of meniscal body beyond the femoral and tibial outer border line. A displacement index, defined as the ratio of meniscal overhang to meniscal width, was used to quantify meniscal displacement.Results The prevalence of radial displacement of the meniscus was 16.7%(52/312) and 13.9%(21/151)in right knee and 19.3%(31/161)in left knee, respectively. There was no significant difference between left and right knee (χ2=1.60,P0.05) and the ratio between medial and lateral meniscus was 7.8:1. The average displacement index was 0.54±0.24. The displacement indices were significant higher in older group (F=3.63,P0.05). The incidence and indices of radial displacement of the meniscus for patients under or above 50 year older were 12.0%(17/142), 0.46±0.22 and 20.6%(35/170), 0.64±0.20,respectively. Difference was highly significant (t=0.84,P0.01). Conclusion It was concluded that radial displacement of the meniscus in knees was not a rare finding with MR imaging in patients with knee symptoms. The incidence increased in older age group. Further investigations were recommended to understand the etiology and clinical significance of the phenomenon of radial displacement of the meniscus.

Computational Theory and Cognition in Representational Momentum and Related Types of Displacement: A reply to Kerzel

Kerzel’s (2006) commentary on Hubbard’s (2005) re-view of the literature on representational momentum and related types of displacement highlights differences of interpretation between Hubbard and Kerzel, but also contains mischaracterizations of Hubbard’s position. In this reply to Kerzel, these differences and mischaracterizations are addressed. Issues are briefly considered that involve the following: whether displacement involves multiple processes; the Marr (1982) framework; the relationship of displacement to internalized physics, goodness of perceived motion, apparent motion, and oculomotor overshoot; generalization from flashed objects to moving objects; necessary and sufficient criteria for displacement; and whether the existence of auditory representational momentum provides evidence for a supramodal account of displacement.

CHARACTER DISPLACEMENT VIA AGGRESSIVE INTERFERENCE IN APPALACHIAN SALAMANDERS

Ecological character displacement occurs when sympatric species compete with one another, resulting in morphological divergence. Theoretically, character displacement can evolve from a number of ecological interactions, such as exploitation, interference, or predation, but most examples describe species competing exploitatively for limiting resources (typically food). Here I report a case of character displacement evolving from aggressive behavioral interference, found in a well-studied system of terrestrial salamanders of the genus Plethodon. Using geometric morphometrics, I found parallel shifts in head shape from allopatry to sympatry in both P. jordani and P. teyahalee, and found significantly greater morphological divergence in sympatry relative to allopatry. Both findings are consistent with ecological character displacement. I also show a significant association between morphology and aggressive behavior, demonstrating a direct link between interference competition and morphology. I present a modified set of the criteria for character displacement that are appropriate for discriminating character displacement via aggressive interference from other possible evolutionary mechanisms. For this example, empirical support satisfying five of the six criteria for character displacement is found. These results provide evidence that morphological variation can be generated by mechanisms other than resource exploitation, which has profound implications for interpreting patterns of biological diversity.