The present study is focusing on the transmission of the monogenean ectoparasite Gyrodactylus salaris Malmberg, 1957, a major pathogen on natural populations of Norwegian Atlantic salmon, Salmo salar L. In laboratory experiments the transmission rate of G. salaris after direct host to host contact was positively correlated with water temperature (1.2, 4,7 and 12.2°C). The transmission of detached G. salaris in the planktonie drift was studied in field experiments where salmon parr were individually isolated for 24 hours in small wire mesh cages suspended in the water column. Ten out of 157 salmon parr (prevalence 6.4%, mean intensity 1.0) contracted G. salaris infections after this exposure. Furthermore, 200 uninfected marked salmon parr were released into the same area of the river. After 24 and 48 hours, respectively 18 and 19 marked parr were caught by electro-fishing. The prevalence of G. salaris was 44.4% (mean intensity 1.9) after 24 hours, rising to 57.9% (mean intensity 2.3) after 48 hours. Gyrodactylids have no specific transmission stage or swimming ability, but detached G. salaris drifting in the water column were found to infect salmon parr. However, the transmission rate was markedly higher to free-living fish, suggesting that transmission routes such as indirect transmission from the substrate or direct contact transmission from infected live and/or dead fish, are relatively more important than transmission by drifting detached parasites.
Transparentní keramika se v laserové technice využívá jako matrice aktivních laserových prostředí vysokovýkonových laserů, kde se začala prosazovat od začátku milénia. Díky svým jedinečným vlastnostem je atraktivní alternativou monokrystalů a skel, kdy nachází využití v široké škále oborů a aplikací zahrnujících optiku, vojenství, medicínu, detektory záření a další., Transparent ceramics have been used as matrices for laser gain media of high power lasers since the beginning of this millennium. Thanks to its unique qualities it has become an attractive alternative to glasses and single crystals, finding applications in the field of optics, defence, medical facilities, radiation detectors and many others., Samuel Paul David, Petr Navrátil, Martin Hanuš, Venkatesan Jambunathan, Martin Divoký, Antonio Lucianetti, Tomáš Mocek., and Obsahuje bibliografické odkazy
Differential pulse voltammetry with a carbon fibre microelectrode (ME) was used in pentobarbital- anaesthetized rats for monitoring the stobadine current (STB.C) on both sides of the blood-brain barrier (BBB) in the arterial bloodstream (BS) and in the corpus striatum (CS). The STB.C exhibited a distinct peak at a polarization voltage 540±30 mV (n=4). The maximum of STB.C in BS attained 2-3 min after the STB administration (2.8 mg/100 g in 1.0 ml saline solution i.a.) was followed by a rapid decrease to about 20 % within next 3 min. The STB readily passed across the BBB: the STB.C peak appeared in the CS in the 3rd minute and continued to rise up to the 30th min. The administration of STB did not prevent a large increase (1347±326 %, n=3) of the catechol-oxidative current (CA.OC) occurring in the CS between the 4th and 5th minute after cardiac arrest. However, a decrease of ME sensitivity to CA.OC in the presence of STB was observed. This fact leads to the speculation whether a similar "quenching" of dopamine by STB could not participate in the protective effects of STB observed in the brain exposed to hypoxia-reoxygenation.
The effects of sleepiness, sleep loss and fatigue have been the focus of literally hundreds of studies dating back to 1896. Sleep disorders, like any other medical condition potentially affecting the safe performance of essential job functions or the safety of co-workers or the general public, require an individual assessment of the employee diagnosed with the condition to determine medical fitness for service and the necessity of any appropriate reasonable accommodations. The medical fitness assessment is a tool for maximum possible operational safety and the health and safety of all personnel in the railway industry. The article describes relevant international medical fitness standards for railway staff with special rules recommended for mental disorders, disorders of the central nervous system and use of alcohol, drugs, and other psychotropic substances.
This paper describes the free transverse vibration analysis of a thin circular plate, subjected to in plane stretching, whilst in interaction with a cylindrical acoustic cavity. An analysis is performed which combines the equations describing the plate and the acoustic cavity to form a matrix equation which, when solved, produces the natural frequencies (latent roots) of the coupled system and associated latent vectors which describe the mode shape coefficients of the plate. After assessing the numerical convergence of the method, results are compared with those from a commercial finite element code (ANSYS). The results analysis is then extended to investigate the effect of stressing upon the free vibration of the coupled system. and Obsahuje seznam literatury