Combined radio-acoustic antenna for the air field complex of acoustic and radioacoustic sounding of the atmosphere

Today the acoustic sounding systems (sodars) are used in many countries to cater for needs of aviation. The interest grows to RAS: the information about high-altitude temperature distribution obtained as a result of radioacoustic atmosphere sounding can be of help for ensuring aircraft take off and landing safety because of connection of the wind shifts with the temperature stratification.A single reflecting antenna for both radio- and acoustic receiving and transmitting at the airfield complex of acoustic and radioacoustic sounding is presented

Low-height radiation field of the coastal radar antenna taking into account troposphere inhomogeneities

A procedure is considered for defining the presence of the tropospheric waveguide based on the shape of the phase-plane portrait, with which it is convenient to describe the behavior of all combinations of radio wave trajectories. A rough model of the spatial distribution of the troposphere refractive index n(x, z) near the sea coastline is given. The minimum information needed for model construction is from two separated vertical profiles of n(z) in the troposphere, which can be obtained by radio-acoustic sounding

Combined acousto-electromagnetic antennas for radioacoustic sounding of the atmosphere

History of the development of combined acousto-electromagnetic antennas for the atmosphere radioacoustic sounding equipment is briefly considered. Advantages and shortages of combined reflector antennas and combined PAAs are pointed out. The modulation effect of sounding electromagnetic radiation at the sound frequency, which is inherent in the combined antennas, is analyzed. Particular attention is given to the statistical aspects of acoustic PAA operation - to the influence of randomness in the sources distribution in antennas on their radiation patterns

The Chemical and Biological Properties of Propolis

The term propolis comes from two Greek words, pro (which means for or in defence of) and polis (which means the city); thus, propolis means in defence of the city or beehive. Propolis is a sticky resinous substance, which is gathered from buds and the bark of trees. It is also known as "bee glue" as bees use it to cover surfaces, seal holes and close gaps in their hives, thus providing a sterile environment that protects them from microbes and spore-producing organisms, including fungi and molds. It can be considered to be a potent chemical weapon against bacteria, viruses, and other pathogenic microorganisms that may invade the bee colony. Also, bees use propolis as an embalming substance, to mummify invaders such as other insects, that have been killed and are too heavy to remove from the colony. Thus, propolis is important for bee health but it also has activity against many human diseases. It is a powerful anti-oxidant and can modulate the activity of reactive oxygen species within the human body. The most studied aspect of propolis is its anti-bacterial activity, which is almost always present at a moderate to high level depending on the exact type of propolis. It is in general more active against Gram positive than Gram negative bacteria, but activity against Gram negative bacteria has been observed. Propolis has been found to be active against a range of viruses and also is almost always active against protozoa such as Tryanosoma brucei and Leishmania donovani. Propolis also shows activity against cardiovascular diseases and diabetes and has immunomodulatory effects. Anti-cancer activity has also been observed. In summary, propolis is remarkable for its range of biological activities and for the variety of its chemical composition. It may be of great importance both to bees and humans