Testicular Anomalies in the Hybridogenetic Frog Pelophylax esculentus (Amphibia: Anura: Ranidae)

Testicular anomalies in the hybridogenetic frog Pelophylax esculentus (586 adults) and two parental species (193) were analyzed. The hybrids were characterized by an increased number of males with testicular anomalies (61%) compared to the parental species (17–20%). Diploid hybrids had more males with abnormal testes when compared to triploid hybrids. Among the hybrids with asymmetrical testes, males with a larger left testis were prevalent

Phonon-mediated tuning of instabilities in the Hubbard model at half-filling

We obtain the phase diagram of the half-filled two-dimensional Hubbard model on a square lattice in the presence of Einstein phonons. We find that the interplay between the instantaneous electron-electron repulsion and electron-phonon interaction leads to new phases. In particular, a d$_{x^2-y^2}$-wave superconducting phase emerges when both anisotropic phonons and repulsive Hubbard interaction are present. For large electron-phonon couplings, charge-density-wave and s-wave superconducting regions also appear in the phase diagram, and the widths of these regions are strongly dependent on the phonon frequency, indicating that retardation effects play an important role. Since at half-filling the Fermi surface is nested, spin-density-wave is recovered when the repulsive interaction dominates. We employ a functional multiscale renormalization-group method that includes both electron-electron and electron-phonon interactions, and take retardation effects fully into account.Comment: 8 pages, 5 figure

Raman scattering study of electron-doped Prx_xCa1−x_{1-x}Fe2_2As2_2 superconductors

Temperature-dependent polarized Raman spectra of electron-doped superconducting Pr$_x$Ca$_{1-x}$Fe$_2$As$_2$ ($x \approx 0.12$) single crystals are reported. All four allowed by symmetry even-parity phonons are identified. Phonon mode of B$_{1g}$ symmetry at 222 cm$^{-1}$, which is associated with the c-axis motion of Fe ions, is found to exhibit an anomalous frequency hardening at low temperatures, that signals non-vanishing electron-phonon coupling in the superconducting state and implies that the superconducting gap magnitude $2\Delta_c < 27$meV.Comment: 4 pages, 3 figure

Raman scattering study of (Kx_xSr1−x_{1-x})Fe2_2As2_2 (xx = 0.0, 0.4)

Polarized Raman spectra of non-superconducting SrFe$_2$As$_2$ and superconducting K$_{0.4}$Sr$_{0.6}$Fe$_2$As$_2$ ($T_c = 37$ K) are reported. All four phonon modes (A$_{1g}$ + B$_{1g}$ + 2E$_g$) allowed by symmetry, are found and identified. Shell model gives reasonable description of the spectra. No detectable anomalies are observed near the tetragonal-to-orthorhombic transition in SrFe$_2$As$_2$ or the superconducting transition in K$_{0.4}$Sr$_{0.6}$Fe$_2$As$_2$.Comment: 4 pages, 4 figures, 2 table

Mutual maintenance of di- and triploid Pelophylax esculentus hybrids in R-E systems: results fro

Background: Interspecies animal hybrids can employ clonal or hemiclonal reproduction modes where one or all parental genomes are transmitted to the progeny without recombination. Nevertheless, some interspecies hybrids retain strong connection with the parental species needed for successful reproduction. Appearance of polyploid hybrid animals may play an important role in the substitution of parental species and in the speciation process. Results: To establish the mechanisms that enable parental species, diploid and polyploid hybrids coexist we have performed artificial crossing experiments of water frogs of Pelophylax esculentus complex. We identified tadpole karyotypes and oocyte genome composition in all females involved in the crossings. The majority of diploid and triploid hybrid frogs produced oocytes with 13 bivalents leading to haploid gametes with the same genome as parental species hybrids usually coexist with. After fertilization of such gametes only diploid animals appeared. Oocytes with 26 bivalents produced by some diploid hybrid frogs lead to diploid gametes, which give rise to triploid hybrids after fertilization. In gonads of all diploid and triploid hybrid tadpoles we found DAPI-positive micronuclei (nucleus-like bodies) involved in selective genome elimination. Hybrid male and female individuals produced tadpoles with variable karyotype and ploidy even in one crossing owing to gametes with various genome composition. Conclusions: We propose a model of diploid and triploid hybrid frog reproduction in R-E population systems. Triploid Pelophylax esculentus hybrids can transmit genome of parental species they coexist with by producing haploid gametes with the same genome composition. Triploid hybrids cannot produce triploid individuals after crossings with each other and depend on diploid hybrid females producing diploid eggs. In contrast to other population systems, the majority of diploid and triploid hybrid females unexpectedly produced gametes with the same genome as parental species hybrids coexist with

The effect of phylogeographic history on species boundaries: a comparative framework in Hyla tree frogs.

Because it is indicative of reproductive isolation, the amount of genetic introgression across secondary contact zones is increasingly considered in species delimitation. However, patterns of admixture at range margins can be skewed by the regional dynamics of hybrid zones. In this context, we posit an important role for phylogeographic history: hybrid zones located within glacial refugia (putatively formed during the Late-Pleistocene) should be better defined than those located in post-glacial or introduced ranges (putatively formed during the Holocene and the Anthropocene). We test this hypothesis in a speciation continuum of tree frogs from the Western Palearctic (Hyla), featuring ten identified contacts between species spanning Plio-Pleistocene to Miocene divergences. We review the rich phylogeographic literature of this group and examine the overlooked transition between H. arborea and H. molleri in Western France using a multilocus dataset. Our comparative analysis supports a trend that contacts zones resulting from post-glacial expansions and human translocations feature more extensive introgression than those established within refugial areas. Integrating the biogeographic history of incipient species, i.e. their age since first contact together with their genetic divergence, thus appears timely to draw sound evolutionary and taxonomic inferences from patterns of introgression across hybrid zones

Thermoelectric properties of Zn_5Sb_4In_(2-δ)(δ=0.15)

The polymorphic intermetallic compound Zn_5Sb_4In_(2−δ) (δ = 0.15(3)) shows promising thermoelectric properties at low temperatures, approaching a figure of merit ZT of 0.3 at 300 K. However, thermopower and electrical resistivity changes discontinuously at around 220 K. Measurement of the specific heat locates the previously unknown temperature of the order-disorder phase transition at around 180 K. Investigation of the charge carrier concentration and mobility by Hall measurements and infrared reflection spectroscopy indicate a mixed conduction behavior and the activation of charge carriers at temperatures above 220 K. Zn_5Sb_4In_(2−δ) has a low thermal stability, and at temperatures above 470 K samples decompose into a mixture of Zn, InSb, and Zn_4Sb_3

ANOMALIES IN TWO SPECIES OF NEWTS FROM NORTH-WESTERN RUSSIA: A COMPARATIVE ANALYSIS

Amount of animals with anomalies in wild populations of tailed amphibians, as a rule, are higher as compare with anurans. This phenomenon could be named as «the paradoxes of high amount of morphological abnormalities in tailed amphibians». The aim of the present paper was to study the paradoxes on the example of two newt species inhabiting north-western Russia. The amount of malformed animals in Lissotriton vulgaris (2,6 %) was two time higher as compared with Triturus cristatus (1,3 %). The number of adults with anomalies (7,5 and 9,0 % in T. cristatus and L. vulgaris, respectively) was much higher when in larvae (0 and 0,6 %). All mentioned malformations were on limbs only. Perhaps, an amount of anomalies in newts increased during life as a result of abnormal regeneration. The proposal is supported by strong correlation between number of animals with anomalies and amount of newts with injuries.Встречаемость животных с аномалиями в природных популяциях хвостатых земноводных, как правило, выше, в сравнении с бесхвостыми. Это явление можно назвать «парадоксом большого количества морфологических аномалий у хвостатых амфибий». Целью настоящей работы было изучение этого парадокса на примере двух видов тритонов, населяющих северо-запад России. Встречаемость аномальных особей у Lissotriton vulgaris (2,6 %) была в два раза выше, по сравнению с Triturus cristatus (1,3 %). Доля взрослых с аномалиями (7,5 и 9,0 % в T. cristatus и L. vulgaris соответственно) была значительно выше, чем у личинок (0 и 0,6 %). Все упомянутые аномалии отмечены только на конечностях. Возможно, частота аномалий у тритонов увеличивается в течение жизни в результате аномальной регенерации. Данное предположение подтверждается существенной корреляцией между частотой животных с аномалиями и встречаемостью тритонов с травмами.Я искренне признателен фонду РФФИ (№ 12-04-01277) за частичную поддержку исследования и Л. Я. Боркину за стимулирующие беседы и обсуждение парадокса повышенного количества аномалий у хвостатых амфибий, а также Ю. С. Литвинчук за помощь в полевых исследованиях и обработке материала

Небезпечна продукція як елемент криміналістичної характеристики злочину, передбаченого ст. 227 КК України

Літвінчук І. С. Небезпечна продукція як елемент криміналістичної характеристики злочину, передбаченого ст. 227 КК України / І. С. Літвінчук // Традиції та новації юридичної науки: минуле, сучасність, майбутнє : матер. Міжнар. наук.-практ. конф. (м. Одеса, 19 трав. 2017 р.). У 2-х т. Т. 2 / відп. ред. Г. О. Ульянова. - Одеса : Видавничий дім "Гельветика", 2017. - С. 775-777

Raman and Infrared-Active Phonons in Hexagonal HoMnO3_3 Single Crystals: Magnetic Ordering Effects

Polarized Raman scattering and infrared reflection spectra of hexagonal HoMnO$_3$ single crystals in the temperature range 10-300 K are reported. Group-theoretical analysis is performed and scattering selection rules for the second order scattering processes are presented. Based on the results of lattice dynamics calculations, performed within the shell model, the observed lines in the spectra are assigned to definite lattice vibrations. The magnetic ordering of Mn ions, which occurs below T$_N$=76 K, is shown to effect both Raman- and infrared-active phonons, which modulate Mn-O-Mn bonds and, consequently, Mn exchange interaction.Comment: 8 pages, 6 figure