Imaging with extended focal depth by means of lenses with radial and angular modulation.

The paper presents imaging properties of modified lenses with the radial and the angular modulation. We analyze three following optical elements with moderate numerical apertures: the forward logarithmic axicon and the axilens representing the radial modulation as well as the light sword optical element being a counterpart of the axilens with the angular modulation. The abilities of the elements for imaging with extended depth of focus are discussed in detail with the help of structures of output images and modulation transfer functions corresponding to them. According to the obtained results only the angular modulation of the lens makes possible to maintain the acceptable resolution, contrast and brightness of the output images for a wide range of defocusing. Therefore optical elements with angular modulations and moderate numerical apertures seem to be especially suitable for imaging with extended focal depth.

[Hospital infections in surgical wards]. / Zakazenia szpitalne w oddzialach zabiegowych.

Nosocomial infections are defined as these which develop during the patient's stay at hospital or shortly after its leaving. In Poland The Society of Nosocomial Infections has been trying to estimate the problem. To deal with it the card for registration of nosocomial infection has been developed. The data used in this project embraces the registration of the nosocomial infections in 1998. The registration cards were sent to the computer centre where they were analysed. 91 hospitals took part in the project. The material consisted of 301,813 cards. The number of patients taken into account in operative departments reached 170,036. In 2,384 cases nosocomial infections were discovered which is 1.4 per cent of all. Nosocomial infections were observed to be similarly frequent in regional hospitals and teashing hospitals. The immune system, not well developed (newborns) or weakened (old age) proroves the danger of nosocomial infection. The time of the infected patient's stay at hospital is twice longer than usually. It needs additional treatment, both operative and pharmacological, which is connected with high costs. The most common systems that usually get infected are respiratory, urinary and wounds. Clinical course of nosocomial infections is rather mild. The programme of nosocomial infections registration allows to better estimate the scale of the problem.