Search results for "Magnification"
showing 8 items of 88 documents
Optical illusions in scanning electron micrographs: the case of the eggshell of Acrosternum (Chinavia) marginatum (Hemiptera: Pentatomidae)
2003
Scanning electron microscopy revealed that-as is common in this family of the Hemiptera-the eggs of the green stink bug Acrosternum (Chinavia) marginatum are roughly barrel-shaped and possess at their apical pole a row of slender extensions, the aero-micropylar processes. The outer surface of the eggshell carries hexagonally arranged pits. The analysis of cross-fractured eggshells showed that the pits have slender basal extensions with transverse diaphragms. When scanning electron micrographs of the egg surface of A. marginatum are viewed upside down, the perception flips and the pits appear as elevations to all observers addressed. Thus, we are dealing with an optical illusion, which is kn…
Diagnostic of craniofacial asymmetry : literature review
2009
Facial asymmetry is a common feature in many syndromes, and requires surgery as the only valid treatment option. Routine diagnostic methods (frontal RX, panoramic RX and submentovertex RX) have serious limitations mainly due to the transfer from a three dimensional image to a two dimensional plane. The feasibility of such methods is poorly supported due to inherent projection errors (image magnification, cranial rotation) and identification errors (image quality, precision and reproducibility). The use of computer tomographies represents a substantial improvement in the sense of skeletal and soft tissue structures? reproduction precision. The interpretation of this new data source makes evi…
Use of contemporary technologies and new materials in undergraduate Endodontics teaching.
2021
Background: This study aims to analyze the use of contemporary technologies and materials in undergraduate endodontic teaching in Spain. Material and Methods: The survey was sent to the undergraduate endodontic programme leads in the 23 Spanish dental schools. The survey asked about the use of magnification, ultrasonic devices, electronic apex locator, rotary instruments, root-filling techniques, and bioceramic cements in the teaching of endodontics. Results: The response rate was 91%, and the final number of schools included in the study was twenty. Only two schools (10%) used magnification (loupes or operative microscope). Five schools (25%) used ultrasonic devices to prepare the access c…
Optical analysis to predict outcomes after implantation of a double intraocular lens magnification device.
2007
Purpose To analyze the effect of different optical parameters of the eye on the outcomes of implantation of a double intraocular lens (IOL) magnification device in patients with low vision. Setting Fundacion Oftalmologica del Mediterraneo, Valencia, Spain. Methods The eye's refraction and magnification before and after surgery were evaluated using a theoretical eye model based on paraxial optics approximation. Four parameters on which refraction and magnification are dependent were evaluated: anterior chamber depth (ACD), axial length (AL), mean keratometry (Km), and the distance between the 2 implanted IOLs. The 4 variables were analyzed separately in the first stage. Next, different combi…
Variations of OCT measurements corrected for the magnification effect according to axial length and refractive error in children
2018
Purpose: The aim of this paper was to examine the distribution of macular, retinal nerve fiber layer (RNFL) thickness and optic disc parameters of myopic and hyperopic eyes in comparison with emmetropic control eyes and to investigate their variation according to axial length (AL) and spherical equivalent (SE) in healthy children. Methods: This study included 293 pairs of eyes of 293 children (145 boys and 148 girls), ranging in age from 6 to 17 years. Subjects were divided according to SE in control (emmetropia, 99 children), myopia (100 children) and hyperopia (94 children) groups and according to axial AL in 68 short ([Formula: see text]22.00[Formula: see text]mm, 68), medium (from [For…
Spiral-CT und 3 D-Rekonstruktion des Tracheobronchialbaumes zur Auswahl geeigneter Doppellumentuben vor Einzellungenbeatmung
1997
Purpose To assess the potential of 3-D spiral CT in the selection of adequate double-lumen tubes (DLT) for one-lung-ventilation. Materials and methods 3-D spiral CT of eight different DLTs was performed with standardized acquisition parameters: section thickness 4 mm, table speed 6 mm/s, increment 3 mm and standardised thresholds, window settings and magnification zoom. The accuracy was confirmed by measuring 3-D objects on screen and original DLTs by vernier caliper. 3-D spiral CT was performed in 20 patients preoperatively with slice thickness 4-8 mm, pitch 1-1.5, increment 4-8 mm. To select the adequate DLT size the 3-D reconstructions of the patient's tracheobronchial tree and of the DL…
Customized intraocular telescope implanted in high myopic patients with advanced maculopathy
2011
Purpose To evaluate the results of intraocular personalized telescope implantation to improve distance best corrected visual acuity (BCVA) in high myopic patients having cataract surgery. Methods This prospective non randomized observational study included 16 eyes of 9 consecutive patients with advanced maculopathy associate to high myopia having cataract surgery. Bilateral implantation of the intraocular telescope was performed after phacoemulsification in patients having the requisites. The telescope consists of two lenses a positive high power lens is implanted in the anterior chamber and a negative one is implanted in the posterior chamber. The lenses power, magnification and residual r…
Magnification in apical surgerymusing the endoscope: a review
2011
Objective: A review is made to determine whether the use of the endoscope in endodontic surgery offers advantages in clinical practice, and whether it improves the clinical and radiographic outcomes of the procedure. Material and methods: The main search terms used were: endodontic surgery, apicoectomy, apical surgery, endoscope, and magnification devices . The authors searched the Medline database for articles published up to 1 September 2010. The review included experimental studies comparing endoscopic microstructural findings with the findings of the naked eye or other magnification devices, as well as prospective clinical trials comparing endodontic surgery with or without the use of a…