Na řadě konkrétních příkladů ukážeme, že se sluneční soustava i galaxie velice pozvolna rozpínají rychlostí řádově srovnatelnou s Hubbleovou konstantou. To je samozřejmé V rozporu se zákonem zachování energie. Dále ukážeme, co by mohlo být zdrojem skryté energie způsobující toto rozpínání i zrychlující se rozpínání celého vesmíru., We give several factual examples showing that the Solar System and also galaxies expand very slowly by a speed comparable with the Hubble constant. This, of course, contradicts the law of ener gy conservation. Further, we show what could be the source of dark energy causing this expansion as well as the accelerating expansion of the whole universe., Michal Křížek., and Obsahuje seznam literatury
Ve druhé části článku předložíme další argumenty, které hovoří ve prospěch hypotézy, jež tvrdí, že skrytá energie nepůsobí jenom globálně, ale i lokálně. To naznačuje, že zákon zachování energie nemusí platit. Navíc ukážeme, že skrytá energie způsobující lokální expanzi gravitačně vázaných systémů může pocházet z nepatrně malé, ale kladné hodnoty gravitační aberace, jež je důsledkem konečné rychlosti šíření gravitační interakce a principu kauzality. Předložený mechanismus může i přispívat ke zrychlujícímu se rozpínání vesmíru., In the second part of this paper we give further examples showing that dark energy acts, not only globally, but also locally. This indicates that the law of energy conservation does not hold. Moreover, we demonstrate that the dark energy needed for an accelerated expansion of the universe may come from an extremely small but positive value of gravitational aberration which would result from a finite speed of gravitational interaction and from causality., Michal Křížek., and Obsahuje seznam literatury
Uvádíme a porovnáváme názory největších myslitelů antiky a středověku - Platóna, Aristotela, Augustina a Tomáše Akvinského - na povahu a vlastnosti času. Všímáme si, jak se jimi formulované názory a problémy odrážejí v současné fyzice., Pavel Macků, Jan Novotný., and Obsahuje seznam literatury
Přežití kriticky ohroženého západního poddruhu antilopy Derbyho se neobejde bez zásahu člověka. Unikátní populace v záchovném oborovém chovu, který probíhá v Senegalu pod odborným vedením českých badatelů, se úspěšně rozrůstá. Náš tým zajišťuje management chovu s ohledem na individuální znalost zvířat, demografické a genetické parametry populace a vytváří dlouhodobou strategii pro zachování tohoto vzácného genofondu. and Survival of the critically endangered western subspecies of Derby eland cannot succeed without human intervention. The unique population in a conservation breeding programme running in Senegal under the professional leadership of Czech researchers is successfully increasing. Our team provides breeding management involving individual knowledge of all the animals and the demographic and genetic parameters of the population and it draws up the long-term strategy for its conservation.
Antilopa vraná (Hippotragus niger) zahrnuje 4-5 tradičních poddruhů v jižní a východní Africe. Jedním z nejméně prozkoumaných a nejvzácnějších, ale zároveň nejzajímavějších je H. n. variani z izolované populace v Angole. Diskutována její historie, morfologie, stupeň ohrožení i problematické postavení taxonu na základě molekulárně biologických studií. and The Sable Antelope (Hippotragus niger) includes four to five traditional subspecies inhabiting southern and eastern Africa. One of the least known and rarest, but at the same time the most interesting is H. n. variani from an isolated population in Angola. Its history, morphology, conservation status and rather disputable classification based on the recent studies in molecular genetics are discussed in this article.
The action of two potential anticonvulsants, CM 40907 (10-50 mg/kg i.p.) and SR 41378 (1.25-20 mg/kg i.p.) against metrazol-induced seizures was studied in rats 7, 12, 18 and 25 days old. Two types of motor seizures - minimal, clonic and major, generalized tonic-clonic - were elicited by a 100-mg/kg dose of metrazol (s.c.) and their incidence and latency were evaluated. The severity of seizures was expressed as a score on a 5-point scale. Dimethylsulfoxide, an organic solvent, exhibited anticonvulsant action only in doses far exceeding those used for dissolving the two anticonvulsants. Both drugs suppressed minimal as well as major seizures in all age groups studied in a dose-dependent manner, SR 41378 being approximately four times more potent than CM 40907. The latencies could be measured only in animals given low doses of anticonvulsants. CM 40907 did not change the latencies whereas SR 41378 prolonged them. The severity of seizures was decreased again in a dose-dependent manner. There were only minor changes in the efficacy of CM 40907 among the four age groups. On the contrary, SR 41378 exhibited an extreme efficacy in 7-day-old rat pups, where even the 1.25 mg/kg dose signifcantly decreased the incidence and severity of seizures. The efficacy in the remaining three age groups was approximately at the same level as in adult rats.
Microsporidia are a cause of emerging and opportunistic infections in humans and animals. Although two drugs are currently being used to treat microsporidiosis, concerns exist that albendazole is only selective for inhibiting some species of microsporidia that infect mammals, and fumagillin appears to have been found to be toxic. During a limited sequence survey of the Vittaforma corneae (syn. Nosema corneum Shadduck, Meccoli, Davis et Font, 1990) genome, a partial gene encoding for the ParC topoisomerase IV subunit was identified. The purpose of this set of studies was to determine if fluoroquinolones, which target topoisomerase IV, exert activity against Encephalitozoon intestinalis (syn. Septata intestinalis Cali, Kotler et Orenstein, 1993) and V. corneae in vitro, and whether these compounds could prolong survival of V. corneae-infected athymic mice. Fifteen fluoroquinolones were tested. Of these, norfloxacin and ofloxacin inhibited E. intestinalis replication by more than 70% compared with non-treated control cultures, while gatifloxacin, lomefloxacin, moxifloxacin, and nalidixic acid (sodium salt) inhibited both E. intestinalis and V. corneae by at least 60% at concentrations not toxic to the host cells. These drugs were tested in vivo also, where gatifloxacin, lomefloxacin, norfloxacin, and ofloxacin prolonged survival of V. corneae-infected athymic mice (P < 0.05), whereas moxifloxacin and nalidixic acid failed to prolong survival. Therefore, these results support continued studies for evaluating the efficacy of the fluoroquinolones for treating microsporidiosis and for characterizing the target(s) of these fluoroquinolones in the microsporidia.
Antimicrobial peptides as future therapeutics? Rapid development of bacterial resistance to the most conventional antibiotics has resulted in an intensive search for alternative antimicrobial agents. Antimicrobial peptides which are part of the innate defense system of practically all living organisms represent promising compounds for developing drugs in the fight against resistant pathogens. Antimicrobial peptides kill bacteries by the disruption of their membrane which is substantially different mechanism from that of conventional antibiotics. We describe remarkable group of cationic helical antimicrobial peptides identified in the venom of hymenopteran insects.
The main characteristics of the Antimüllerian hormone from the points of view of biochemistry, molecular genetics, physiological functions and importance for diagnostics in reproductive endocrinology and related biomedical fields are reviewed. The role of the hormone in male and female development, its participation in oocyte maturation including selection of a dominant follicle are summarized, as well as its changes under various pathological situations in both sexes. The physiological changes of serum AMH leves in the life span in both sexes and their alterations under various pathological conditions are provided, too., R. Hampl, M. Šnajderová, T. Mardešić., and Obsahuje bibliografii a bibliografické odkazy