Health of ophthalmologists as a prerequisite of quality medical services.

Objective: Introduction: The effectiveness and efficiency of the medical sector workforce directly depend on health of medical professionals. Scientific literature pays considerable attention to the health of surgeons, physicians, obstetricians, gynecologists, infectionists and dentists paying very little, if any, attention to health problems of ophthalmologists. This study is intended to bridge this gap.

[Fractal aspects of the taxic diversity].

Two approaches are suggested for describing taxic diversity as a fractal, or self-similar, object. One of them called "sampling approach" is based on necessity of taking into account the sampling process and on proceeding from the real ecological practice of exploration of the community structure. Verification of this approach is fulfilled using a multifractal analysis of the generic diversity of vascular plants of the National Park "Samarskaya Luka".

Seasonal changes in polar lipids in fronds of the ferns Dryopteris filix-mas and Matteuccia struthiopteris.

The distribution pattern of total lipids, glyco- and phospholipids, and one betaine lipid (DGTS) in the fronds ofthe ferns Dryopteris filix-mas and Matteuccia struthiopteris was studied. The lipid composition of the embryo leaflets forming a bud, or "treble clef", and that of fully opened leaves changed throughout the growth season. The maximum amount of DGTS in clefs and mature leaves was detected at the beginning of the season.

Hydrocarbons, fatty acids, and lipids of freshwater grasses of the Potamogetonaceae family.

The composition of hydrocarbons, fatty acids, and of total, polar, and neutral lipids was studied in freshwater Potamogetonaceae grasses collected in two different regions of the Volga river. More than 40 fatty acids and hydrocarbons were separated and identified by chromato-mass spectrometry. The variability of lipid characteristics of plants of the same family is discussed.

Seasonal variations of diacylglyceryl-N,N,N-trimethylhomoserine content in Polypodiophyta.

Diacylglyceryl-N,N,N-trimethylhomoserine (DGTS) belongs to a family of three known betaine lipids. It is synthesized by a number of bacteria, fungi, brown, red and green algae, in addition to lichens, and is also found in higher plants Bryophyta, Equisetophyta and Polydiophyta. It has been determined that DGTS plants can be DGTS-positive or DGTS-negative.