Incident data 586 INDEX

Mortality data are frequently used in cohort studies as opposed to incidence data because of the relative ease of obtaining information on deaths. In particular, the advent of the National Death Index has made mortality data more readily available. While all states maintain registries of incident cancer cases, many of the registries are relatively new and data quality can vary from state to state. Investigators conducting follow-up studies are required to comply with each state s requirements for use of the data. For cancers such as pancreatic cancer where survival is poor, mortality data is an excellent surrogate for the risk of the disease. For other cancers where the survival is much better, such as testicular cancer, mortality is a poor estimator of incidence. Table 15.5 describes the 5-year survival for several selected cancer sites for the period 1996-2004. As evident from the table, there is a considerable difference in survival rates for cancer of different sites. The 5-year survival rate for pancreatic cancer was only 5.1% compared to a survival rate of 98.9% for prostate cancer (SEER 2008). 

Circular dichroism arises from the same optically active transitions responsible for the Cotton effects observed in ORD curves, but unlike ORD it is an absorption, not a dispersion, phenomenon. Hence, the CD effect is restricted to the region of the transition and can be interpreted more straightforwardly. Both ORD and CD can best be understood if one imagines the incident plane-polarized beam resolved into two in-phase circularly polarized beams whose vectors rotate in opposite directions. A difference in index of refraction between the left and right circularly polarized beams results in rotation of the transmitted plane polarized beam while differential absorption of the two circularly polarized beams results in depolarization of the transmitted beam, so that an incident plane-polarized beam whose frequency is within that of an optically active absorption band becomes both rotated and elliptically polarized upon passage through the sample. This depolarization effect is CD, and the measured parameter is (et — er), the difference in extinction coefficient between the left and right circularly polarized beams. The data is usually recorded as the specific ellipticity, defined as ... 

These measurements were made on an Auto EL-II Ellipsometer (Rudolph Research, Flanders, NJ). The laser source was a 1 mW continuous wave helium/ neon laser, with a wavelength of 6328 A. The angle of incidence was 70° and the spot size 2-3 mm. A refractive index of 1.5 was utilized for all the silane layers. The data were analysed on a Hewlett-Packard 85 computer using film 85 software package, version 30, program 13, and the film thickness was calculated using the McCrackin program. 

The Collection is a source of reference patterns for pure crystalline phases. The data may be helpful in identifying known zeolitic materials and indexing their diffraction patterns. Because so many factors related to both the zeolite crystal and the diffraction instrument affect powder diffraction data, phase identification is not always straightforward and frequently requires additional data. Considerable care should be exercised in comparing calculated diffraction patterns to experimental patterns. For example, the use of fixed versus variable incident slits on a powder diffractometer can drastically change the relative intensities of a diffraction pattern, and it should be emphasized that calculated patterns are only as accurate as the structure refinements on which they are based. 

This procedure has been used to determine droplet size in sprays. Oseillations in the curve relating x and D can be smoothed out by the use of an incident laser beam having a broad speetral bandwidth [83]. An accumulation of independent scattering intensities from multiple scatterers ean be used to measure the mean droplet size of a group [84]. This procedure has been applied to water sprays and the experimental data confirmed by phase Doppler anemometry [85]. The applicability of the polarization ratio technique is strongly influenced by the complex refractive index of the dispersed media and is limited to media having a relative refractive index below about 1.44 [86]. 

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