The Ability to Perceive a Minor Change in Luminosity Lab Report

The Ability to Perceive a Minor Change in Luminosity - Lab Report Example To perform the CS test (CST), the basic requirements for all four tests were: 1) to have an adequate luminance level required for each test; 2) to have precise test distance; and 3) to perform each test approximately at the same eye sight level as that of test charts. The CST luminance requirement for Pelli-Robson charts was 60–120 cd/m2, while for Vistech6000 and Cambridge plates the adequate luminance levels were 103–240 cd/m2 and 100 cd/m2 respectively. The Lux value required for Cardiff cards CST was equal to that of the gray background cards. For each test the required Lux level was verified by using a Lux meter. The value of precise test distance varies from test to test. For Pelli-Robson CST the required separation was 1 m. For Vistech and Cambridge plates CSTs, the required separation was 3.048 m and 6 m respectively, and within the acuity limit for Cardiff cards CST (Wood and Wood 1995). After having all basic requirements for each test, the test charts/cards w ere hung vertically on a wall one after the other. To determine CS values, corresponding observations were made: first with the right eye (without any correction), starting horizontally on each line of charts/cards and moving from the left hand side to the right hand side, and then from top to bottom for each letter/symbol on the chart /card. The tests were repeated for a plastic in front of an eye pretended to be a cataract. The tests were concluded when two or three letters/symbols were named incorrectly. The corresponding observations for CS were recorded. The CS function (CSF) value obtained for monocular right eye (RE) testing without cataract through Pelli-Robson CST is 1.95 while with cataract it is 1.65 – a quite lower value (fig. 4 and 5) . From Cardiff CST the evaluated contrast (%) values for monocular.

How Are Program Libraries Concatenated Assignment - 1

How Are Program Libraries Concatenated - Assignment Example Concatenation allows the data sets to be processed in a sequence automatically (Ebbers et al., 2011). Â  - NEW designate that a new data set will be developed. The job has a unique access to the data set while it is running. Additionally, the data set should not exist on the same volume containing the new data, set or be in the system or user catalog (Ebbers et al., 2012). Â  - SHR shows that a data set is already existing and that various concurrent jobs are able to share access and at the same time run. Mainly, all concurrent jobs should specify SHR (Ebbers et al., 2012). Â  DISP=NEW shows that a file is new and does not exist in the system. DISP=OLD is used to show that a file will be overwritten, and hence the old data will disappear and replaced with new data. DISP=MOD implies that a new data is to be added at the end of a file (Ebbers et al., 2012). Â  An indexed VSAM file is used when the data sets are held in control areas (CA) and control intervals (CI). The indexed VSAM file is used when the records are ordered according to a collating sequence of an embedded prime key field. Also, it is used where the order of the records is fixed or where the records are commanded by their relative key. In addition, VSAM files are used to insert new records into a suitable place in a file as well as the records that follow, which are moved to a new location. The VSAM file is used when there is no need for reorganization (Singh, 2011). Â  The advantage of using a VSAM file is that various datasets are accessed efficiently and quickly because of its organization. Another advantage is that records are inserted in an effective way. The disadvantage of VSAM file usage is that the records are deleted from the disk physically rather than being removed logically (Somnath, 2010). Â  - IEBGENER is a utility that copies one sequential data set to another.