Home About us Contact
|
Home About us Contact | ||
|
|
||
Same Manufacturer (same + manufacturer)
Selected AbstractsAssessment of the increase in variability when combining volumetric data from different scannersHUMAN BRAIN MAPPING, Issue 2 2009Santiago Reig Abstract In multicenter MRI studies, pooling of volumetric data requires a prior evaluation of compatibility between the different machines used. We tested the compatibility of five different scanners (2 General Electric Signa, 2 Siemens Symphony, and a Philips Gyroscan) at five different sites by repeating the scans of five volunteers at each of the sites. Using a semiautomatic method based on the Talairach atlas, and SPM algorithms for tissue segmentation (multimodal T1 and T2, or T1-only), we obtained volume measurements of the main brain lobes (frontal, parietal, occipital, temporal) and for each tissue type. Our results suggest that pooling of multisite data adds small error for whole brain measurements, intersite coefficient of variation (CV) ranging from 1.8 to 5.2%, respectively, for GM and CSF. However, in the occipital lobe, intersite CV can be as high as 11.7% for WM and 17.3% for CSF. Compared with the intersite, intrasite CV values were always much lower. Whenever possible, T1 and T2 tissue segmentation methods should be used because they yield more consistent volume measurements between sites than T1-only, especially when some of the scans were obtained with different sequence parameters and pixel size from those of the other sites. Our study shows that highest compatibility among scanners would be obtained using equipments of the same manufacturer and also image acquisition parameters as similar as possible. After validation, data from a specific ROI or scanner showing values markedly different from the other sites might be excluded from the analysis. Hum Brain Mapp, 2009. © 2007 Wiley-Liss, Inc. [source] Application of a digital technique in evaluating the reliability of shade guidesJOURNAL OF ORAL REHABILITATION, Issue 5 2004E. Cal summary, There appears to be a need for a reliable method for quantification of tooth colour and analysis of shade. Therefore, the primary objective of this study was to show the applicability of graphic software in colour analysis and secondly to investigate the reliability of commercial shade guides produced by the same manufacturer, using this digital technique. After confirming the reliability and reproducibility of the digital method by using self-assessed coloured images, three shade guides of the same manufacturer were photographed in daylight and in studio environments with a digital camera and saved in tagged image file format (TIFF) format. Colour analysis of each photograph was performed using the Adobe Photoshop 4·0 graphic program. Luminosity, and red, green, blue (L and RGB) values of each shade tab of each shade guide were measured and the data were subjected to statistical analysis using the repeated measure Anova test. The L and RGB values of the images taken in daylight differed significantly from those of the images taken in studio environment (P < 0·05). In both environments, the luminosity and red values of the shade tabs were significantly different from each other (P < 0·05). It was concluded that, when the environmental conditions were kept constant, the Adobe Photoshop 4·0 colour analysis program could be used to analyse the colour of images. On the other hand, the results revealed that the accuracy of shade tabs widely being used in colour matching should be readdressed. [source] Mechanical Behavior and Failure Analysis of Prosthetic Retaining Screws after Long-term Use In Vivo.JOURNAL OF PROSTHODONTICS, Issue 3 2008Part 1: Characterization of Adhesive Wear, Structure of Retaining Screws Abstract Purpose: The general aim of this study and those presented in Parts 2,4 of this series was to characterize the structure, properties, wear, and fracture of prosthetic retaining screws in fixed detachable hybrid prostheses after long-term use in vivo. This part of the overall investigation addresses whether there are differences in thread wear between the screws closest to the fulcrum and those that are farthest from the fulcrum in fixed detachable hybrid prostheses. Materials and Methods: The total number of prosthetic retaining screws used in this study was 100 (10 new and 90 used). New screws (controls) from Nobel Biocare (NB) were divided into Group 1 (slotted) and Group 2 (hexed). Ninety used screws (in service 18,120 months) were retrieved from fixed detachable hybrid prostheses in 18 patients (5 screws from each patient, 60 from NB and 30 from Sterngold). The used screws were divided into 18 groups. Additionally, each group was subdivided into A and B categories. Category A contained the middle three prosthetic screws, which were considered the farthest screws from the fulcrum line. Category B contained the most posterior two screws, which were considered the screws closest to the fulcrum line. All 100 screws were subjected to thorough, nondestructive testing. Results: Light and scanning electron microscopic examination of all used screws for each group revealed surface deterioration of the active profile of the screw threads consistent with adhesive wear. The observed thread profile deterioration ranged from mild to severe. The wear was aggressive enough to cause galling, which led to thinning of the threads and, in severe cases, to knife-edges at thread crests. In ten groups, the most anterior three screws exhibited more wear than the most posterior two screws. In addition to thread wear, severe plastic deformation was detected on the bottom part of each screw for three groups, and a long external longitudinal crack was detected in one screw of Group 2. Conclusions: The findings of this study and those presented in Parts 2,4 demonstrate that different retaining screws from the same manufacturer and/or from different manufacturers have different geometrical design, microstructures, major alloy constituents, and microhardness, and that these differences influence their preload and fractured load values. In this part of the overall investigation, the occurrence of galling as a result of wear involving prosthetic retaining screws appears to be an inevitable and unavoidable consequence of long-term use in vivo in fixed detachable hybrid prostheses regardless of the intended/original preload value. The galling rate is greater on the middle three screws compared to the most posterior two screws in fixed detachable hybrid prostheses. The wear pattern is consistent with an adhesive wear mechanism; however, this study does not provide enough data to support a definitive analysis. [source] Incident investigation: Process to identify root causes of mechanical failures,PROCESS SAFETY PROGRESS, Issue 1 2006A. M. (Art) Dowell III P.E. This paper describes an actual incident investigation into unexpected premature failure of sealed diaphragm pressure transmitters in a chemical process. Some nontypical investigation tools from the CCPS Guidelines for Investigating Chemical Process Incidents (2nd edition) were used. A typical failure allowed a release of a corrosive process fluid with potential injury to personnel. The failures also required a shutdown of the process with loss of production. The cause of the problem was elusive; pressure transmitters from the same manufacturer had no problems in a similar process unit, although component designs differed between the two units. The investigation included confirmation of materials of construction, photographic and visual analyses of failed components, simulation of assembly of the pressure transmitter in the process and measurement of torque values, and brainstorming of possible failure mechanisms. Several hypotheses were tested using a fact,hypothesis matrix to determine most likely cause scenarios. Similarly, a matrix was used to illustrate which scenarios could be prevented by which corrective actions. The investigation included a root cause analysis tree to confirm cause scenarios. The paper discusses the incident investigation process, including diversity of skills on the investigation team, and how each of the tools was used. The paper also discusses the communication of the findings to operations. © 2005 American Institute of Chemical Engineers Process Saf Prog, 2006 [source] Identifying the origins of fishing gear ingested by seabirds: a novel multivariate approachAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 6 2010Cindy Ridley Abstract 1.The global decline of albatrosses (Diomedidae: Procellariiformes) is thought to have occurred largely as a direct result of fishery-related mortality. Albatrosses and other large petrels interact with fisheries in several ways, including scavenging used bait and discarded offal, which may contain hooks. 2.Hooks that are ingested by breeding birds are often fed to chicks which subsequently regurgitate them shortly before fledging. 3.In this study a series of mathematical (cladistic, cluster and principal components) analyses are applied to a sample of 241 items of fishing gear (hook, snood and hook/snood unit) collected from seabird nest sites on Bird Island, South Georgia, and 44 reference gear items provided by four South Atlantic regional fisheries. 4.The five separate analyses failed to assign most gear to a particular fishery or to identify any consistent annual trends. The homogeneous nature of the material, which was largely derived from the same manufacturers, meant that gear origin could not be determined. This suggests that hooks found at seabird colonies in this, and potentially other regions, will be of limited use in identifying offending fisheries, unless operators are obliged to deploy gear with unique marks in the future. 5.Nevertheless, it is suggested that this approach should work effectively where birds interact with a range of fisheries targeting different species using variable gear. This study therefore represents an innovative approach to the characterization of lost fishing gear with potentially widespread application. Copyright © 2010 John Wiley & Sons, Ltd. [source] | |||||||||||||