Phase distortions of attosecond pulses produced by resonance-enhanced high harmonic generation

Resonant enhancement of high harmonic generation can be obtained in plasmas containing ions with strong radiative transitions resonant with harmonic orders. The mechanism for this enhancement is still debated. We perform the first temporal characterization of the attosecond emission from a tin plasma under near-resonant conditions for two different resonance detunings. We show that the resonance considerably changes the relative phase of neighbouring harmonics. For very small detunings, their phase locking may even be lost, evidencing strong phase distortions in the emission process and a modified attosecond structure. These features are well reproduced by our simulations, allowing their interpretation in terms of the phase of the recombination dipole moment

Morfologija i sekvence mitohondrijske DNK pokazuju da su Plecotus alpinus Kiefer & Veith, 2002 i Plecotus microdontus Spitzenberger, 2002 sinonimi Plecotus macrobullaris Kuzjakin, 1965

Genetic and morphological analyses of long-eared bats from Northern Ossetia and other Caucasian localities revealed that the sister clade of Plecotus auritus discovered in the Eastern Alps (SPITZENBERGER et al., 2001) and described as a new species by Spitzenberger (SPITZENBERGER et al., 2002) (Plecotus microdontus) and by KIEFER & VEITH (2002) (Plecotus alpinus) is conspecific with Plecotus macrobullaris Kuzyakin, 1965, described as a subspecies of P. auritus, from the vicinity of Vladikavkaz. The valid name for this species therefore is Plecotus macrobullaris. P. macrobullaris also occurs in central and eastern Turkey. Morphological as well as genetic analyses differentiate between an eastern and a western group within P. macrobullaris. From a morphological comparison of specimens of P. macrobullaris with the type specimens of Plecotus wardi from Kashmir we conclude that macrobullaris is not conspecific with wardi.Genetske i morfološke analize dugouhih šišmiša iz Sjeverne Osetije i drugih kavkaskih lokaliteta otkrile su da je sestrinska grupa vrste Plecotus auritus, otkrivena u Istočnim Alpama (SPITZENBERGER et al., 2001) i opisana kao nova vrsta od Spitzenberger (SPITZENBERGER et al., 2002) (Plecotus microdontus) i KIEFER & VEITH (2002) (Plecotus alpinus), konspecifična s vrstom Plecotus macrobullaris Kuzyakin, 1965, opisanom kao podvrsta od P. auritus iz blizine Vladikavkaza. Zato je validno ime ove vrste Plecotus macrobullaris. P. macrobullaris se također javlja u središnjoj i istočnoj Turskoj. Morfološke i genetičke analize pokazuju razliku istočne i zapadne grupe unutar P. macrobullaris. Iz morfološke usporedbe primjeraka P. macrobullaris s tipskim primjercima Plecotus wardi iz Kašmira zaključujemo da macrobullaris nije konspecifičan s wardi

Does Giant Magnetoresistance Survive in Presence of Superconducting Contact?

The giant magnetoresistance (GMR) of ferromagnetic bilayers with a superconducting contact (F1/F2/S) is calculated in ballistic and diffusive regimes. As in spin-valve, it is assumed that the magnetization in the two ferromagnetic layers F1 and F2 can be changed from parallel to antiparallel. It is shown that the GMR defined as the change of conductance between the two magnetic configurations is an oscillatory function of the thickness of F2 layer and tends to an asymptotic positive value at large thickness. This is due to the formation of quantum well states in F2 induced by Andreev reflection at the F2/S interface and reflection at F1/F2 interface in antiparallel configuration. In the diffusive regime, if only spin-dependent scattering rates in the magnetic layers are considered (no difference in Fermi wave-vectors between spin up and down electrons) then the GMR is supressed due to the mixing of spin up and down electron-hole channels by Andreev reflection.Comment: 7 pages, 4 figures, submitted to Phys.Rev.Let

Diode effect in magnetic tunnel junctions

The influence on the I-V characteristics and tunnel magnetoresistance (TMR), of impurities embedded into the insulating barrier I separating the two ferromagnetic electrodes F of a magnetic tunnel junction, was theoretically investigated. When the energy of the electron's bound state at the impurity site is close to the Fermi energy, it is shown that the current and TMR are strongly enhanced in the vicinity of the impurity. If the position of the impurity inside the barrier is asymmetric, e.g. closer to one of the interfaces F/I, the I-V characteristic exhibits a quasidiode behavior. The case of a single impurity and of a random distribution of impurities within a plane were both studied.Comment: 8 pages, 5 figure

The Comparative Analysis of the Identification of Parasitic Fungi Races Affecting the Soil and Cultivated Vegetable and Cucurbits Crops in the Astrakhan Region

The habitat of plant pathogens does not remain constant and undergoes significant changes. Therefore, the reasons have to be revealed: the emergence of fungal infectious matter in the soil; the infection source and rate, which may have epiphytotic character under environmental factors of the disease development and consequently lead to the reduction in the yield of vegetable and cucurbits crops. As a result, it is necessary to conduct monitoring and objective diagnosis of the phytosanitary condition of the planting of vegetables and melons. In this case, the identification of parasitic fungi races of the Astrakhan region remains relevant and timely

UCN anomalous losses and the UCN capture cross-section on material defects

Experimental data shows anomalously large Ultra Cold Neutrons (UCN) reflection losses and that the process of UCN reflection is not completely coherent. UCN anomalous losses under reflection cannot be explained in the context of neutron optics calculations. UCN losses by means of incoherent scattering on material defects are considered and cross-section values calculated. The UCN capture cross-section on material defects is enhanced by a factor of 10^4 due to localization of UCN around defects. This phenomenon can explain anomalous losses of UCN.Comment: 13 pages, 4 figure

GRANIT project: a trap for gravitational quantum states of UCN

Previous studies of gravitationally bound states of ultracold neutrons showed the quantization of energy levels, and confirmed quantum mechanical predictions for the average size of the two lowest energy states wave functions. Improvements in position-like measurements can increase the accuracy by an order of magnitude only. We therefore develop another approach, consisting in accurate measurements of the energy levels. The GRANIT experiment is devoted to the study of resonant transitions between quantum states induced by an oscillating perturbation. According to Heisenberg's uncertainty relations, the accuracy of measurement of the energy levels is limited by the time available to perform the transitions. Thus, trapping quantum states will be necessary, and each source of losses has to be controlled in order to maximize the lifetime of the states. We discuss the general principles of transitions between quantum states, and consider the main systematical losses of neutrons in a trap.Comment: presented in ISINN 15 seminar, Dubn

К видовому разнообразию нематодофауны семейства Corvidae Vigors, 1825 в дельте реки Волги

The purpose of the research is to systematize the long-term data on study of nematode fauna of Corvidae family birds of Volga river delta. Materials and methods. Data of helminthological researches carried out during the period from 1936 to 2017 in different landscape zones of Volga river delta are included into the project. The study of the species composition of the nematode fauna was carried out based on analysis of own and literature data received during helminthological autopsy of the Corvidae family birds belonging to 3 species: hooded crow (Corvus cornix Linnaeus, 1758), rook (Corvus frugilegus Linnaeus, 1758), magpie (Picapica Linnaeus, 1758). Traditional methods were used during collection and handling of helminthological material (Skryabin, 1928; Dubinina, 1955). Nematodes have been fixed by the mixture made from equal parts of 70% alcohol, lactic acid and 50% glycerol, 4% formalin solution or in Barbagallo liquid. Nematodes have been identified by famous indicators. Results and discussion. 480 specimen of Corvidae family birds, 170 specimen of which had been infested by nematode worms, were investigated in order to study helminthofauna at Volga river delta from 1936 to nowadays. Having summarized the literature data with the results from own study of Corvidae family parasitophauna we have made a taxonomical list including 17 species of nematodes. During the period from 1976 to 2017 we have been discovering 3 species of nematodes for the first time: Microtetrameres helix (Cram, 1927) - in a rook, Oxyspirura sygmoidea (Molin, 1860) - in a rook, a magpie and a hooded crow, Pseudaprocta decorata (Li, 1933) - in a magpie. 2 species of nematodes have been registered in Corvidae family as in new hosts in the studied region too. Baruscapillaria corvorum (Rudolphi, 1819) - in a hooded crow, a magpie and Diplotriaena tricuspis (Fedtschenko, 1874) - in a hooded crow.Цель исследований: систематизировать многолетние данные по изучению нематодофауны врановых птиц дельты реки Волги. Материалы и методы. В работу включены сведения гельминтологических исследований, проводившихся в период с 1936 до 2017 гг. в различных ландшафтных зонах дельты реки Волги. Изучение видового состава нематодофауны проводили на основе анализа собственных и литературных данных, полученных при проведении гельминтологических вскрытий птиц семейства врановые, принадлежащих к 3 видам: ворона серая (Corvus cornix Linnaeus, 1758), грач (Corvus frugilegus Linnaeus, 1758), сорока (Pica pica Linnaeus, 1758). При сборе и обработке гельминтологического материала использованы традиционные методики (Скрябин, 1928; Дубинина, 1955). Нематод фиксировали смесью из равных частей 70%-ного спирта, молочной кислоты и 50%-ного глицерина, 4%-ным раствором формалина, или в жидкости Барбагалло. Нематод идентифицировали по известным определителям. Результаты и обсуждение. С 1936 г. по настоящее время в целях изучения гельминтофауны в дельте реки Волги исследовано 480 экз. врановых птиц, 170 из которых были инвазированы круглыми червями. Обобщив литературные данные с результатами собственных исследований паразитофауны врановых, нами составлен таксономический список, включающий 17 видов нематод. В период с 1976 до 2017 гг. у врановых нами впервые в регионе обнаружено 3 вида нематод: Microtetrameres helix (Cram, 1927) - у грача, Oxyspirura sygmoidea (Molin, 1860) - у грача, сороки и серой вороны, Pseudaprocta decorata (Li, 1933) - у сороки. Также, в исследуемом регионе 2 вида нематод зарегистрированы у врановых как у новых хозяев: Baruscapillaria corvorum (Rudolphi, 1819) - у серой вороны и сороки и Diplotriaena tricuspis (Fedtschenko, 1874) - у серой вороны

Conservation genetics of the pond bat (Myotis dasycneme) with special focus on the populations in northwestern Germany and in Jutland, Denmark

Conservation genetics is important in the management of endangered species, helping to understand their connectivity and long‐term viability, thus identifying populations of importance for conservation. The pond bat (Myotis dasycneme) is a rare species classified as “Near Threatened” with a wide but patchy Palearctic distribution. A total of 277 samples representing populations in Denmark, Germany, Latvia, Hungary, and Russia were used in the genetic analyses; 224 samples representing Denmark, Germany, and Russia were analyzed at 10 microsatellite loci; 241 samples representing all areas were analyzed using mitochondrial D‐loop and cytochrome B sequences. A Bayesian clustering approach revealed two poorly resolved clusters, one representing the Danish and German groups and the other the Russian group. However, significantly different pairwise FST and DEST estimates were observed between the Danish and German groups and between the Danish and Russian groups suggesting a recent population structure. These conflicting results might be attributed to the effect of migration or low resolution due to the number of microsatellite markers used. After concatenating the two mitochondrial sequences, analysis detected significant genetic differentiation between all populations, probably due to genetic drift combined with a founder event. The phylogenetic tree suggested a closer relationship between the Russian and Northern European populations compared to the Hungarian population, implying that the latter belongs to an older ancestral population. This was supported by the observed haplotype network and higher nucleotide diversity in this population. The genetic structuring observed in the Danish/German pond bat stresses the need for a cross‐border management between the two countries. Further, the pronounced mtDNA structuring, together with the indicated migration between nearby populations suggest philopatric female behavior but male migration, emphasizes the importance of protecting suitable habitat mosaics to maintain a continuum of patches with dense pond bat populations across the species' distribution range