Two interacting active regions of different ages have been studied over two days using white light and Hα observations as well as magnetograma. Different series of homologous flares and the formation of a filament in tbe region were analysed and an interpretation of these events is proposed.
Cryptosporidium parvum causes life-threatening diarrhoea in immunocompromized, especially AIDS patients and the efficiency of proposed anti-cryptosporidial therapies is limited or doubtful. An immunosuppressed adult rat model of C. parvum infection was developed for screening molecules candidate for curative and preventive activity in human cryptosporidiosis. Among 31 drugs tested, lasalocid (2-10 mg/kg/24 h), and sinefungin (2-10 mg/kg/24 h), exhibited some activity against C. parvum infection. Oral sinefungin therapy resulted in a dose related suppression of oocysts shedding, which correlated with oocyst disappearance from ileum sections and was also efficient in preventing infection. Relapses were observed after discontinuation of curative sinefungin therapy, which suggests that the biliary tract, a major location and parasite reservoir which sustains persisting infection, was not cleared of parasites by the drug. Improved therapeutic procedures with sinefungin (or analogues) will result from current pharmacological studies.
The sequences of 10 conservative regions (CR) of minicircles of 6 selected isolates of freshwater fish try-panosomes have typical organization of this region with high degree of sequence conservation. The comparison with CRs of other trypanosomatids showed that freshwater fish trypanosomes represent a compact separate group within the genus Trypanosoma. The alignment of all sequences obtained revealed, however, the existence of 2 types of CRs in sequenced minicirclcs, with the differences concentrated in a short region. Taxonomic consequences of these results arc discussed.
The survival of Encephalitozoon cuniculi Lcvaditi, Nicolau et Schoen, 1923 spores suspended in distilled water and exposed at defined temperatures was investigated. Infectivity of E. cuniculi spores was tested by inoculation of SCID mice. There was no marked loss of infectivity of spores stored at 4°C for two years or frozen at -12°C and -24°C for 1, 8, and 24 h. Although there was a remarkable loss of infectivity, spores remained infective after freezing at -70°C for 1 and 8 h. Heating at 60°C and 70°C for 5 min and 1 min, respectively, rendered the microsporidia non-infective. These findings demonstrate that E. cuniculi spores suspended in water can survive freezing temperatures but lost infectivity in water that reached a temperature of 60°C at 5 min.
The article deals with white-light spectral interferometry used for measuring the thickness of SiO2 thin films on a silicon substrate. A slightly dispersive Michelson interferometer with a cube beam splitter and a fibre optic spectrometer are used when one of the interferometer mirrors is replaced by the SiO2 thin film on the silicon wafer. Thickness of the SiO2 thin film is determined by comparison of recorded spectral interferogram with theoretical one provided that the optical constants for materials involved in the structure are known. This method was applied for the thickness determination of four SiO2 thin-film samples. and Článek se zabývá využitím spektrální interferometrie v bílém světle pro měření tloušťky tenkých vrstev SiO2 na křemíkovém substrátu. Využívá se mírně disperzního Michelsonova interferometru s polopropustným zrcadlem ve tvaru kostky a vláknově optického spektrometru pro záznam interferogramů, kdy jedno ze zrcadel interferometru je nahrazeno křemíkovou deskou s tenkou vrstvou SiO2. Tloušťku tenké vrstvy SiO2 určujeme porovnáním zaznamenaného spektrálního interferogramu s interferogramem teoretickým za předpokladu znalosti optických konstant tenké vrstvy a substrátu. Tuto metodu jsme využili pro určení tloušťky čtyř vzorků s SiO2 tenkou vrstvou.