38 research outputs found
The genus <i>Nitzschia</i> on the South Shetland Islands and James Ross Island
The purpose of this study was to present LM and SEM observations of Nitzschia taxa encountered on the South Shetland Islands and James Ross Island. During the ongoing taxonomical revision of the freshwater and limno-terrestrial diatom flora on the South Shetland Islands and James Ross Island (Maritime Antarctic Region) eight unknown taxa belonging to the genus Nitzschia were found. These taxa were previously force-fitted into European names such as N. commutata or N. perminuta, but detailed light and scanning electron microscopical observations allowed their separation from the already known taxa and resulted in the description of eight new species. The paper discusses all twelve Nitzschia taxa found in the Maritime Antarctic Region. New taxa are compared to the morphologically most similar taxa and their ecology and biogeography are discussed. Although the genus Nitzschia is present worldwide, a large number of Nitzschia taxa have a restricted distribution within the Antarctic Region, showing a clear bioregionalism
PHP194 Pharmacoeconomic Guideline for Positive Drug List Application Purposes Implemented In Bulgaria
Quadrupole and octupole collectivity in the semi-magic nucleus 80206Hg126
The first low-energy Coulomb-excitation measurement of the radioactive, semi-magic, two proton-hole nucleus 206Hg, was performed at CERN's recently-commissioned HIE-ISOLDE facility. Two γ rays depopulating low-lying states in 206Hg were observed. From the data, a reduced transition strength B(E2;21+→01+)=4.4(6) W.u. was determined, the first such value for an N=126 nucleus south of 208Pb, which is found to be slightly lower than that predicted by shell-model calculations. In addition, a collective octupole state was identified at an excitation energy of 2705 keV, for which a reduced B(E3) transition probability of 30−13+10 W.u. was extracted. These results are crucial for understanding both quadrupole and octupole collectivity in the vicinity of the heaviest doubly-magic nucleus 208Pb, and for benchmarking a number of theoretical approaches in this key region. This is of particular importance given the paucity of data on transition strengths in this region, which could be used, in principle, to test calculations relevant to the astrophysical r-process
Four new <i>Luticola</i> taxa (Bacillariophyta) from Maritime Antarctica
The paper describes four new Luticola taxa from the South Shetland Archipelago, Antarctica: Luticola neglecta sp. nov., L. bogaertsiana sp. nov., L. contii sp. nov. and L. olegsakharovii sp. nov. All new taxa are studied using both light and scanning electron microscopy and compared to other morphologically similar species from (sub-)Antarctica and elsewhere in the world. Data on their ecology and biogeography are added