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

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

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

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

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

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

Solvability of singular integral equations with rotations and degenerate kernels in the vanishing coefficient case

By means of Riemann boundary value problems and of certain convenient systems of linear algebraic equations, this paper deals with the solvability of a class of singular integral equations with rotations and degenerate kernel within the case of a coefficient vanishing on the unit circle. All the possibilities about the index of the coefficients in the corresponding equations are considered and described in detail, and explicit formulas for their solutions are obtained. An example of application of the method is shown at the end of the last section

The anomaly of the oxygen bond-bending mode at 320 cm−1^{-1} and the additional absorption peak in the c-axis infrared conductivity of underdoped YBa2_{2}Cu3_{3}O7−δ_{7-\delta} single crystals revisited by ellipsometricmeasurements

We have performed ellipsometric measurements of the far-infrared c-axis dielectric response of underdoped YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ single crystals. Here we report a detailed analysis of the temperature-dependent renormalization of the oxygen bending phonon mode at 320 cm$^{-1}$ and the formation of the additional absorption peak around 400-500 cm$^{-1}$. For a strongly underdoped YBa$_{2}$Cu$_{3}$O$_{6.5}$ crystal with T$_{c}$=52 K we find that, in agreement with previous reports based on conventional reflection measurements, the gradual onset of both features occurs well above T$_{c}$ at T*$\sim$150 K. Contrary to some of these reports, however, our data establish that the phonon anomaly and the formation of the additional peak exhibit very pronounced and steep changes right at T$_{c}$. For a less underdoped YBa$_{2}$Cu$_{3}$O$_{6.75}$ crystal with T$_{c}$=80 K, the onset temperature of the phonon anomaly almost coincides with T$_{c}$. Also in contrast to some previous reports, we find for both crystals that a sizeable fraction of the spectral weight of the additional absorption peak cannot be accounted for by the spectral-weight loss of the phonon modes but instead arises from a redistribution of the electronic continuum. Our ellipsometric data are consistent with a model where the bilayer cuprate compounds are treated as a superlattice of intra- and inter-bilayer Josephson-junctions

Cubic curves from instanton counting

We investigate the possibility to extract Seiberg-Witten curves from the formal series for the prepotential, which was obtained by the Nekrasov approach. A method for models whose Seiberg-Witten curves are not hyperelliptic is proposed. It is applied to the SU(N) model with one symmetric or antisymmetric representations as well as for SU(N_1)xSU(N_2) model with (N_1,N_2) or (N_1,\bar{N}_2) bifundamental matter. Solutions are compared with known results. For the gauge group product we have checked the instanton corrections which follow from our curves against direct instanton counting computations up to two instantons.Comment: 30 pages, v2. typos fixed, referenced adde