Treatment of patients with failed sutures in the small intestine

The suture insufficiency have occurred in 26 (15%) patients after operative treatment of 179 patients with different diseases of small intestine. The main methods of treatment of this patients are the surgical procedures, intestinal intubation, rational antibioticotherapy, the hemostasis correction for the postoperative peritonitis liquidation.     

Transmission and reflection characteristics at concrete block wallsin the UHF bands proposed for future PCS

Buildings such as warehouses, supermarkets and retail department stores typically have walls constructed from concrete (cinder) blocks. The web and void design of the individual blocks and their arrangement within a wall creates a periodic structure, which exhibits frequency dependent transmission and reflections characteristics in the UHF bands proposed for future Personal Communication Systems (PCS). For higher frequencies, higher order Floquet modes excited at the periodic structure can propagate away from the wall, suggesting that significant power can be carried away from the wall in non-specular directions. Indoor propagation prediction models must consider the non-specular paths exited by walls with a periodic nature in order to account for all of the scattered power. In this work, plane wave reflection and transmission characteristics for typical concrete block walls are examined theoretically and experimentally to determine the frequency dependence of the specularly and non-specularly transmitted and reflected fields     

Mechanisms governing UHF propagation on single floors in modernoffice buildings

Because of the potential implementation of indoor wireless local area networks (LANs) and personal communication networks (PCNs) it is important to understand propagation of signals in the UHF band inside buildings. The authors explore features of office buildings of modern construction that influence propagation between transmitter and receiver located on the same floor. One feature is the clear space between ceiling and furnishings or floor that results in excess attenuation of the signal. A second feature is reflection and transmission at interior and exterior walls. Diffraction at corners and propagation along the exterior wall are also shown to be a significant means for radiation to reach the receivers. The influences of the first two features are combined into a computer program that evaluates the sector average signal, which is then compared with measurements     

UHF propagation prediction for wireless personal communications

Propagation characteristics of radio signals in the UHF band place fundamental limits on the design and performance of wireless personal communications systems, such as cellular mobile radio (CMR), wireless LANs, and personal communication services (PCS). Because the radio link is direct to each subscriber, the prediction of signal characteristics is most important in urban areas where subscriber density is high, and the buildings have a profound influence on the propagation. The paper starts by reviewing the characteristic signal variations observed in CMR systems employing high base station antennas to cover macrocells having radius out to 20 km. Theoretical models incorporating diffraction are shown to explain the observed range dependence and shadow loss statistics. For the low base station antennas envisioned to cover microcells of radius out to 1 km for PCS applications, signal propagation is more strongly dependent on the building environment and on the location of the antennas in relation to the buildings. Various levels of theoretical modeling of this dependence are discussed in conjunction with measurements made in various building environments. Finally, the paper discusses advances in site specific prediction for outdoor and indoor propagation     

Bilateral averaging over receiving and transmitting areas foraccurate measurements of sector average signal strength inside buildings

In defining path loss for narrowband systems, it is common to introduce the concept of the sector or local average in order to remove the rapid (Rayleigh or Rician) fading. As originally developed for cellular mobile radio (CMR) systems, the sector average is obtained from the spatial average of the received signal as the mobile traverses a path of 20 or so wavelengths. This approach has also been applied indoors with the assumption that a unique average could be obtained by moving either end of the radio link. Unlike the CMR path for indoor propagation, however, both ends of the radio link are in a rich multipath environment. It is shown both theoretically and experimentally that moving both ends of the link is required to achieve a unique average. When averaging is accomplished by moving only one end, the result can experience variations of as much as ±2 dB when the other end is moved by a fraction of a wavelength     

Broadband wireless access

This article reviews the technologies and potential markets, applications, and architectures for broadband wireless access. The emergence of wireless communications for cellular systems is presented, together with its projected future evolution to mobile wideband systems. The field of broadband access systems, services, and network architectures is also covered, and then systems for broadband wireless communications for indoor local area networks and outdoor public fixed access networks are discussed. Broadband wireless access systems are emerging as a new and growing area of telecommunications, since the ability to provide access without extensive installation of copper or fiber infrastructures make wireless technology well suited for broadband services. Finally, some of the key enabling technologies, such as adaptive antennas and video compression, and the future architectural directions of broadband wireless networks are presented     

Mechanisms governing propagation between different floors inbuildings

The potential implementation of wireless radio local area networks (LANs) and personal communication services inside buildings requires a thorough understanding of signal propagation within buildings. In this work the authors develop a theory which explains propagation between a transmitter and a receiver located on different floors of a building. Depending on the structure of the building and the location of the antennas, either direct ray propagation through floors or diffraction outside the building will determine the propagation characteristics and range dependence of the signal sector average as the number of floors between the transmitter and the receiver is increased