The most common hazards in the forestry that may induce disorders of the musculoskeletal system are vibrations, unfavorable microclimatic conditions, noise, over-time working hours, work load and long-term repeated movements. The objective of this study was to analyze the prevalence of musculoskeletal diseases and its difference among workers engaged in various jobs in the forestry. Two groups of workers were selected: woodcutters operating with chain-saw (N=33) and other loggers (N=32). Selected workers were of the similar age and had similar total length of employment as well as the length of service in the forestry. Both groups of workers employed in the forestry had the high prevalence of musculoskeletal diseases (woodcutters 69.7% and other loggers 62.5%, respectively). Degenerative diseases of spinal column were very frequent, in dependently of the type of activity in the forestry. Non-significantly higher risk of carpal tunnel syndrome was found in woodcutters with chain-saw compared to workers having other jobs in the forestry (OR=3.09; 95%CI=0.64-19.72). The lateral epicondylitis was found only in woodcutters operating with chain-saw with the prevalence of 18.2%.

A structure-based description of excitation migration in multireaction center light harvesting systems is introduced. The description is an extension of the sojourn expansion, which decomposes excitation migration in terms of repeated detrapping and recapture events. The approach is applied to light harvesting in the trimeric form of cyanobacterial photosystem I (PSI). Excitation is found to be shared between PSI monomers and the chlorophylls providing the strongest respective links are identified. Excitation sharing is investigated by computing cross-monomer excitation trapping probabilities. It is seen that on the average there is a nearly 40% chance of excitation cross transfer and trapping, indicating efficient coupling between monomers. The robustness and optimality of the chlorophyll network of trimeric PSI is examined.

An algebraic Kekule structure of a benzenoid hydrocarbon is obtained from an ordinary Kekule structure by inscribing into each hexagon the number of π-electrons which (according to this Kekule structure) belong to this hexagon. We show that in the case of catafusenes, there is a one-to-one correspondence between ordinary and algebraic Kekule structures. On the other hand, in the case of perifusenes, one algebraic Kekule structure may correspond to several ordinary Kekule structures.