Variaciones estacionales de parámetros reproductivos, calidad espermática y enzimas del plasma seminal en carneros texel

El objetivo del presente trabajo fue determinar el efecto de la estación del año (fotoperíodo) sobre la circunferencia escrotal (CE), peso testicular (PT), volumen testicular (VT), capacidad de servicio (CS), concentración plasmática de testosterona, características cuali-cuantitativas del semen fresco y enzimas del plasma seminal de carneros de raza Texel. El estudio se realizó en la pampa húmeda de Argentina (37°45’ S, 58°18’ O, 130 msnm). Se utilizaron seis carneros jóvenes (2 años de edad) y las determinaciones realizadas, peso vivo, CE, PT [PT=0,5533 x (L) x (A)2], VT [VT=4/3 x (n) x (L/2) x (A/2)2] (siendo L=longitud y A=ancho del testículo) y testosterona plasmática se realizaron una vez por mes. La prueba de CS se realizó dos veces por estación y la evaluación del semen se efectuó dos veces por semana durante el mes central de cada estación. Las variables fueron analizadas mediante modelos lineales mixtos para medidas repetidas en el tiempo (R Core Team). En verano (Marzo) se observaron los mayores valores (media ±EE; p<0,05) de CE (33,8±0,6 cm), PT (467,5±15,2 g) y VT (442,3±8,5 cm3). El número promedio de montas totales fue mayor (p<0,05) en invierno (21) respecto de la primavera (9). La mayor concentración plasmática de testosterona (p<0,05) fue determinada en verano (Enero=13,2±2,9 ng/ml) y la menor en invierno (Sep- tiembre=0,13±0,1 ng/ml). Eyaculados (n=192) fueron evaluados y los mejores parámetros de calidad seminal fueron determinados en otoño e invierno. Los patrones anuales de las enzimas alanina-amino-transferasa y lactato-deshidrogenasa mostraron una significativa variación estacional (p<0,05), con la más alta actividad durante la estación reproductiva. Por otro lado, las concentraciones de aspartato-amino-transferasa, gama-glutamil-transpeptidasa y fosfatasa alcalina fueron más bajas en verano. Los resultados sugieren que los carneros Texel presentan un mayor potencial reproductivo en la estación de otoño (fotoperíodo decreciente) en esta latitud

Algebraic characterization of the Wess-Zumino consistency conditions in gauge theories

A new way of solving the descent equations corresponding to the Wess-Zumino consistency conditions is presented. The method relies on the introduction of an operator $\delta$ which allows to decompose the exterior space-time derivative $d$ as a $BRS$ commutator. The case of the Yang-Mills theories is treated in detail.Comment: 16 pages, UGVA-DPT 1992/08-781 to appear in Comm. Math. Phy

The Expectation Monad in Quantum Foundations

The expectation monad is introduced abstractly via two composable adjunctions, but concretely captures measures. It turns out to sit in between known monads: on the one hand the distribution and ultrafilter monad, and on the other hand the continuation monad. This expectation monad is used in two probabilistic analogues of fundamental results of Manes and Gelfand for the ultrafilter monad: algebras of the expectation monad are convex compact Hausdorff spaces, and are dually equivalent to so-called Banach effect algebras. These structures capture states and effects in quantum foundations, and also the duality between them. Moreover, the approach leads to a new re-formulation of Gleason's theorem, expressing that effects on a Hilbert space are free effect modules on projections, obtained via tensoring with the unit interval.Comment: In Proceedings QPL 2011, arXiv:1210.029

Yang-Mills gauge anomalies in the presence of gravity with torsion

The BRST transformations for the Yang-Mills gauge fields in the presence of gravity with torsion are discussed by using the so-called Maurer-Cartan horizontality conditions. With the help of an operator \d which allows to decompose the exterior spacetime derivative as a BRST commutator we solve the Wess-Zumino consistency condition corresponding to invariant Chern-Simons terms and gauge anomalies.Comment: 24 pages, report REF. TUW 94-1

Dimensional crossover in topological matter: Evolution of the multiple Dirac point in the layered system to the flat band on the surface

We consider the dimensional crossover in the topological matter, which involves the transformation of different types of topologically protected zeroes in the fermionic spectrum. In the considered case, the multiple Dirac (Fermi) point in quasi 2-dimensional system evolves into the flat band on the surface of the 3-dimensional system when the number of atomic layers increases. This is accompanied by formation of the spiral nodal lines in the bulk. We also discuss the topological quantum phase transition at which the surface flat band shrinks and changes its chirality, while the nodal spiral changes its helicity.Comment: 13 pages, 7 figure

Substrate-induced band gap opening in epitaxial graphene

Graphene has shown great application potentials as the host material for next generation electronic devices. However, despite its intriguing properties, one of the biggest hurdles for graphene to be useful as an electronic material is its lacking of an energy gap in the electronic spectra. This, for example, prevents the use of graphene in making transistors. Although several proposals have been made to open a gap in graphene's electronic spectra, they all require complex engineering of the graphene layer. Here we show that when graphene is epitaxially grown on the SiC substrate, a gap of ~ 0.26 is produced. This gap decreases as the sample thickness increases and eventually approaches zero when the number of layers exceeds four. We propose that the origin of this gap is the breaking of sublattice symmetry owing to the graphene-substrate interaction. We believe our results highlight a promising direction for band gap engineering of graphene.Comment: 10 pages, 4 figures; updated reference

Role of surface roughness in hard x-ray emission from femtosecond laser produced copper plasmas

The hard x-ray emission in the energy range of 30-300 keV from copper plasmas produced by 100 fs, 806 nm laser pulses at intensities in the range of 10$^{15}-10^{16}$ W cm$^{-2}$ is investigated. We demonstrate that surface roughness of the targets overrides the role of polarization state in the coupling of light to the plasma. We further show that surface roughness has a significant role in enhancing the x-ray emission in the above mentioned energy range.Comment: 5 pages, 4 figures, to appear in Phys. Rev.