When performed with chondroitinase ABC or agents other than chymopapain Percutaneous lumbar discectomymanual or automated, is considered medically necessary for treatment of herniated lumbar discs when all of the following are met: Member is otherwise a candidate for open laminectomy; and Member has failed 6 months of conservative treatment; and Diagnostic studies show that the nuclear bulge of the disc is contained within the annulus i. Percutaneous lumbar diskectomy is considered experimental and investigational for all other indications because its effectiveness for indications other than the one listed above has not been established.
In John Snow determined the source of a cholera outbreak in London by marking points on a map depicting where the cholera victims lived, and connecting the cluster that he found with a nearby water source. This was one of the earliest successful uses of a geographic methodology in epidemiology.
While the basic elements of topography and theme existed previously in cartographythe John Snow map was unique, using cartographic methods not only to depict but also to analyze clusters of geographically dependent phenomena.
This work was originally drawn on glass plates but later plastic film was introduced, with the advantages of being lighter, using less storage space and being less brittle, among others. When all the layers were finished, they were combined into one image using a large process camera.
Once color printing came in, the layers idea was also used for creating separate printing plates for each color. Computer hardware development spurred by nuclear weapon research led to general-purpose computer "mapping" applications by the early s.
A rating classification factor was also added to permit analysis.
It supported a national coordinate system that spanned the continent, coded lines as arcs having a true embedded topology and it stored the attribute and locational information in separate files.
As a result of this, Tomlinson has become known as the "father of GIS", particularly for his use of overlays in promoting the spatial analysis of convergent geographic data.
It was developed as a mainframe -based system in support of federal and provincial resource planning and management. Its strength was continent-wide analysis of complex datasets. The CGIS was never available commercially.
This was renamed in to MapInfo for Windows when it was ported to the Microsoft Windows platform. This began the process of moving GIS from the research department into the business environment. More recently, a growing number of free, open-source GIS packages run on a range of operating systems and can be customized to perform specific tasks.
The most common method of data creation is digitizationwhere a hard copy map or survey plan is transferred into a digital medium through the use of a CAD program, and geo-referencing capabilities.
With the wide availability of ortho-rectified imagery from satellites, aircraft, Helikites and UAVsheads-up digitizing is becoming the main avenue through which geographic data is extracted. Heads-up digitizing involves the tracing of geographic data directly on top of the aerial imagery instead of by the traditional method of tracing the geographic form on a separate digitizing tablet heads-down digitizing.
Just as a relational database containing text or numbers can relate many different tables using common key index variables, GIS can relate otherwise unrelated information by using location as the key index variable.
Any variable that can be located spatially, and increasingly also temporally, can be referenced using a GIS. Units applied to recorded temporal-spatial data can vary widely even when using exactly the same data, see map projectionsbut all Earth-based spatial—temporal location and extent references should, ideally, be relatable to one another and ultimately to a "real" physical location or extent in space—time.
Related by accurate spatial information, an incredible variety of real-world and projected past or future data can be analyzed, interpreted and represented. GIS uncertainties[ edit ] GIS accuracy depends upon source data, and how it is encoded to be data referenced.
Land surveyors have been able to provide a high level of positional accuracy utilizing the GPS -derived positions. In developing a digital topographic database for a GIS, topographical maps are the main source, and aerial photography and satellite imagery are extra sources for collecting data and identifying attributes which can be mapped in layers over a location facsimile of scale.
The scale of a map and geographical rendering area representation type[ clarification needed ] are very important aspects since the information content depends mainly on the scale set and resulting locatability of the map's representations.
A quantitative analysis of maps brings accuracy issues into focus. The electronic and other equipment used to make measurements for GIS is far more precise than the machines of conventional map analysis. GIS file formats GIS data represents real objects such as roads, land use, elevation, trees, waterways, etc.
Real objects can be divided into two abstractions: Traditionally, there are two broad methods used to store data in a GIS for both kinds of abstractions mapping references: Points, lines, and polygons are the stuff of mapped location attribute references.
A new hybrid method of storing data is that of identifying point clouds, which combine three-dimensional points with RGB information at each point, returning a " 3D color image ".This article may be too long to read and navigate comfortably.
Please consider splitting content into sub-articles, condensing it, or adding or removing subheadings. (November ). effects. Generally, eddy-current effects are divided into skin effect and proximity effect.
The classical deﬁnition of skin-effect loss is the extra AC loss in a single isolated conductor which is carrying a time-varying current.
And the correspond-ing deﬁnition of proximity-effect loss in a winding is deﬁned as the total eddy-current loss minus the . eddy current probe,current volatility and complexity of the electromagnetic field, leading to sensor measurement accuracy more difficult to achieve micron metin2sell.com current commercial eddy current sensor accuracy is usually 10 m,to reach 4 m accuracy of the above,the cost significantly increases.
Non-destructive techniques are used widely in the metal industry in order to control the quality of materials. Eddy current testing is one of the most extensively used non-destructive techniques for inspecting electrically conductive materials at very high speeds that does not require any contact between the test piece and the sensor.
This paper includes an overview of the fundamentals and. Improvement of the Eddy Current Method of Non-Destructive Testing with Pulsed Mode Excitation Oleksandr DUGIN 1, eddy current sensor to widen of functional capabilities of the eddy current non- accuracy of a informative signal decrement.
It is determined that it is very impotent to. ASME Biennial Stability and Damped Critical Speeds of a Flexible Rotor in Fluid-Film Bearings J. W. Lund 1 ASME Biennial Experimental Verification of Torquewhirl-the Destabilizing Influence of Tangential Torque J. M. Vance and K.