Effect of Crystal Quality on HCP-BCC Phase Transition in Solid 4He

The kinetics of HCP-BCC structure phase transition is studied by precise pressure measurement technique in 4He crystals of different quality. An anomalous pressure behavior in bad quality crystals under constant volume conditions is detected just after HCP-BCC structure phase transition. A sharp pressure drop of 0.2 bar was observed at constant temperature. The subsequent pressure kinetics is a non-monotonic temperature function. The effect observed can be explained if we suppose that microscopic liquid droplets appear on the HCP-BCC interphase region in bad quality crystals. After the interphase region disappearance, these droplets are crystallized with pressure reduction. It is shown that this effect is absent in high quality thermal-treated crystals.Comment: 4 pages, 4 figure

Fast Diffusion Process in Quenched hcp Dilute Solid 3^3He-4^4He Mixture

The study of phase structure of dilute $^3$He - $^4$He solid mixture of different quality is performed by spin echo NMR technique. The diffusion coefficient is determined for each coexistent phase. Two diffusion processes are observed in rapidly quenched (non-equilibrium) hcp samples: the first process has a diffusion coefficient corresponding to hcp phase, the second one has huge diffusion coefficient corresponding to liquid phase. That is evidence of liquid-like inclusions formation during fast crystal growing. It is established that these inclusions disappear in equilibrium crystals after careful annealing.Comment: 7 pages, 3 figures, QFS200

NMR Study of Disordered Inclusions in the Quenched Solid Helium

Phase structure of rapidly quenched solid helium samples is studied by the NMR technique. The pulse NMR method is used for measurements of spin-lattice $T_1$ and spin-spin $T_2$ relaxation times and spin diffusion coefficient $D$ for all coexisting phases. It was found that quenched samples are two-phase systems consisting of the hcp matrix and some inclusions which are characterized by $D$ and $T_2$ values close to those in liquid phase. Such liquid-like inclusions undergo a spontaneous transition to a new state with anomalously short $T_2$ times. It is found that inclusions observed in both the states disappear on careful annealing near the melting curve. It is assumed that the liquid-like inclusions transform into a new state - a glass or a crystal with a large number of dislocations. These disordered inclusions may be responsible for the anomalous phenomena observed in supersolid region.Comment: 10 pages, 3 figure

Phylogeny and phylogeography of the roaches, genus Rutilus (Cyprinidae), at the Eastern part of its range as inferred from mtDNA analysis

The genus Rutilus is a widely distributed lineage of cyprinids and ranges from West Europe to East Siberia. Although matrilineal phylogeny and phylogeography of western species were already studied, roaches from remaining part of the range were not examined. Phylogenetic analysis based on cytochrome b sequences detected the following three major phylogenetic clades: (i) R. frisii, (ii) R. rutilus s. str., and (iii) group of six Ponto–Caspian taxa: R. caspicus, R. heckelii, R. rutilus aralensis, R. rutilus lacustris, R. schelkovnikovi, and R. stoumboudae. Our results suggest that these “species” within Ponto–Caspian clade could be a single species (R. lacustris by priority of description). The Ponto–Caspian clade is most widely distributed among others and covers the freshwaters from the Aegean Sea basin to Laptev Sea tributaries. Both R. rutilus s. str. and Ponto–Caspian clades sympatrically occur in Black Sea and Caspian Sea basins, Azov Sea itself, and even in drainage of White Sea. The vastest zone of contact (approximately 1700 km) was detected in the Volga basin. The spatial pattern of haplotype diversity and the shape of haplotype network argued for multiple refugia in Ponto–Caspian region as well as a rapid post-glacial colonization of Volga River and Siberia

Phylogeny and phylogeography of the roaches, genus Rutilus (Cyprinidae), at the Eastern part of its range as inferred from mtDNA analysis

The genus Rutilus is a widely distributed lineage of cyprinids and ranges from West Europe to East Siberia. Although matrilineal phylogeny and phylogeography of western species were already studied, roaches from remaining part of the range were not examined. Phylogenetic analysis based on cytochrome b sequences detected the following three major phylogenetic clades: (i) R. frisii, (ii) R. rutilus s. str., and (iii) group of six Ponto–Caspian taxa: R. caspicus, R. heckelii, R. rutilus aralensis, R. rutilus lacustris, R. schelkovnikovi, and R. stoumboudae. Our results suggest that these “species” within Ponto–Caspian clade could be a single species (R. lacustris by priority of description). The Ponto–Caspian clade is most widely distributed among others and covers the freshwaters from the Aegean Sea basin to Laptev Sea tributaries. Both R. rutilus s. str. and Ponto–Caspian clades sympatrically occur in Black Sea and Caspian Sea basins, Azov Sea itself, and even in drainage of White Sea. The vastest zone of contact (approximately 1700 km) was detected in the Volga basin. The spatial pattern of haplotype diversity and the shape of haplotype network argued for multiple refugia in Ponto–Caspian region as well as a rapid post-glacial colonization of Volga River and Siberia

Rarely naturalized, but widespread and even invasive: the paradox of a popular pet terrapin expansion in Eurasia

The North American terrapin, the red-eared slider, has globally recognized invasive status. We built a new extensive database using our own original and literature data on the ecology of this reptile, representing information on 1477 water bodies throughout Eurasia over the last 50 years. The analysis reveals regions of earliest introductions and long-term spatio-temporal dynamics of the expansion covering now 68 Eurasian countries, including eight countries reported here for the first time. We established also long-term trends in terms of numbers of terrapins per aquatic site, habitat occupation, and reproduction success. Our investigation has revealed differences in the ecology of the red-eared slider in different parts of Eurasia. The most prominent expression of diverse signs of invasion success (higher portion of inhabited natural water bodies, higher number of individuals per water body, successful overwintering, occurrence of juvenile individuals, successful reproduction, and establishment of populations) are typical for Europe, West Asia and East Asia and tend to be restricted to coastal regions and islands. Reproduction records coincide well with the predicted potential range based on climatic requirements but records of successful wintering have a wider distribution. This invader provides an excellent and possibly unique (among animals) example of wide alien distribution, without the establishment of reproducing populations, but through the recruitment of new individuals to rising pseudopopulations due to additional releases. Therefore, alongside the potential reproduction range, a cost-effective strategy for population control must take in account the geographical area of successful wintering. Graphical abstrac