Thus mortality reduction may be the result of new cancer treatments or of screening diffusion or both [ 18, 19]; evidence of efficacy for prostate cancer screening, however, is yet inconclusive and also recent studies yielded conflicting results [ 20- 22].
It is also important to note that, if we compare incidence rates as an indicator of screening intensity, PSA screening diffusion in Umbria seems lower than in many other Italian geographic areas covered by cancer registration; indeed highly variable incidence rates among neighbouring Italian areas probably reflect different screening activities [ 23].
Indeed it is present also in the US data [ 17, 18] and may be associated with changing diagnostic activities since a pronounced increase in mortality occurred earlier in US than in Umbria, and in that country also screening diffusion occurred earlier.
The flicker frequency of each strip light was converted to 1200 Hz with special ballasts (Osram Quicktronic QT-Eco 1 58/230-240), and the light from each rig was diffused by a single sheet of Rosco 216 (Germany) UV-transmitting white diffusion screen to provide an even and homogenous illumination source.
Less dramatic but equally fascinating is an unprepossessing square of membrane known as a diffusion screen that was used, in a process known as gas diffusion, to enrich uranium for Britain's atomic weapons programme.
He [Buelteman] then lays each sample on color transparency film and covers it with a diffusion screen which is positioned on a piece of sheet metal sandwiched between plexiglas, floating in liquid silicone".
at a constant velocity of 16°/s (spf = 0.06 cycles/deg; contrast = 100%) onto the diffusion screen.
Minimal contrast (Min): A homogeneous gray image with no contrast was projected onto the diffusion screen with the same light intensity as the averaged intensity under maximum contrast.
Using a digital light projector (HP vp6111), moving and still vertical sine-wave gratings (spatial frequency (spf) = 0.06 cycles/deg) were projected onto a cylindrical diffusion screen.
Try using lamps behind the diffusion screen for an illuminated background.
