We analyzed the abundance, distribution and niche overlap of species (Pianka's Ojk index) in tenebrionid beetle communities inhabiting different biotopes in Tyrrhenian and Adriatic sand dunes. The rank abundance distribution of the different species has the form of a geometric series in both communities as predicted by the niche preemption hypothesis for communities in harsh environments. Mean niche overlap values did not deviate significantly from null expectations, which indicates random interspecific interactions. These results, coupled with evidence of species habitat preferences, led us to conclude that the community organization of tenebrionid species inhabiting coastal dunes is determined more by habitat preferences than interspecific competition., Simone Fattorini, Davide Bergamaschi, Cristina Mantoni, Alicia T. R. Acosta, Andrea Di Giulio., and Obsahuje bibliografii
The impacts of aquatic invasive species vary from the population to ecosystem level most strikingly through modifications to native communities, often leading to a decline in native species. A primary impact mechanism is competitive displacement of native by invasive species through resource partitioning. However, the trophic interactions between native and invasive species occupying the same habitat remain poorly understood, particularly at the early stages of invasion. This study used stable isotope analysis of two co-occurring populations of invasive topmouth gudgeon, Pseudorasbora parva and native Caucasian dwarf goby, Knipowitschia caucasica in a highly productive shallow lake to characterize overlap of potential trophic niches. The trophic niches of both species were divergent, with no overlap. Mixing models suggest some inter-specific dietary differences. The trophic niche of the Caucasian dwarf goby was slightly and non-significantly larger than that of topmouth gudgeon. These results suggest that when introduced outside of their natural range, topmouth gudgeon might integrate into new fish communities via the exploitation of resources that are underexploited by native fishes, which could also explain the high invasion success of the species.
Aim of the study was to test the effect of nicotine (NIC) and kainic acid (KA) co-treatment in immature rats. Male Wistar albino rats (two different age groups) were chosen for the study. Experiments started on postnatal day (PD) 8 or 21 and animals were treated twice a day for three days with nicotine, fourth day KA was administered. Animals at PD12 (PD25 respectively) were examined electrophysiologically for cortical epileptic afterdischarges (ADs). First cortical ADs in PD12 animals were longer, when compared to PD25 rats (group treated with both substances). Nor NIC or KA treatment affected the length of discharges in PD12 rats. Older experimental group exhibited the shortening of the first ADs (group treated with NIC and KA, compared with groups exposed to single treatment). Few changes were found in KA treated group – 2nd and 4th ADs were shorter when compared with first ADs. These results demonstrate that NIC treatment played minor role in seizure susceptibility of PD12 rats, sensitivity to NIC differs during ontogenesis and subconvulsive dose of KA influenced the length of discharges only in PD25 animals., V. Riljak ... [et al.]., and Obsahuje seznam literatury
The article is divided into three parts. The first section summarizes the key scientific contributions of Niels Bohr and also clarifies selected misleading interpretation concerning the so-called Copenhagen interpretation of complementarity. The second part shows Bohr as the thinker who solved scientific problems in light of a cross-disciplinary search. Furthermore, the section presents the atmosphere of the so-called Copenhagen spirit that reigned in Bohr‘s Institute for Theoretical Physics. The last part deals with Bohr as a director of the Institute and the development or transformations of the Institute from its foundation in 1920 till the beginning of the Second World War., Filip Grygar., and Obsahuje seznam literatury
The first part of the article outlines Bohr's complementary way of thinking with which he amongst others approached the solution of atomic events in his three famous articles On the constitution of atoms and molecules from 1913. It also shows Bohr not only as a physicist, but as an interdisciplinary thinker and philanthropist. The second part gives a summary of the conference commemorating the centenar of the Bohr model of the atom, which claims to at least to partially for some gaps in the perception of this remarkable figure., Výklad stability atomu podal Niels Bohr ve svých třech stěžejních článcích nazvaných O konstituci atomů a molekul v roce 1913. V nich jedinečným způsobem aplikoval na Rutherfordův model atomu dosud nespojované předpoklady (klasické předpoklady a Planckovu kvantovou hypotézu nebo Balmerovu-Rydbergovu konstantu). To mu umožnilo podat vysvětlení čárového spektra (nejenom) vodíku a v neposlední řadě ho jeho teorie dovedla až k revolučnímu pojetí struktury molekul. V české odborné a laicky zainteresované veřejnosti tak přetrvává představa Bohra především jako fyzika nebo jen strůjce modelu atomu vodíku. Takový obraz o Bohrovi je velmi zavádějící. Ve fyzice Bohr dosáhl řady dalších významných příspěvků a současně byl interdisciplinárním myslitelem, jenž se zabýval filosofií, psychologií, biologií nebo jazykem. Nárokem konference ke stému výročí Bohrova modelu atomu tak bylo alespoň zčásti zaplnit některá bílá místa ve vnímání této pozoruhodné osobnosti., Patrik Čermák, Filip Grygar., and Obsahuje seznam literatury