A new Megatheriinae skull (Xenarthra, Tardigrada) from the pliocene of northern venezuela – Implications for a giant sloth dispersal to central and North America

A skull of a ground sloth from the Pliocene San Gregorio Formation documents a northern neotropical occurrence of a megatheriine that addresses issues on intraspecific variation and biogeography. The new specimen is broadly similar in size and morphology to that of Proeremotherium eljebe from the underlying Codore Formation in the Urumaco Sequence, differing in several features such as a longer basicranial area and a more posteriorly projected basioccipital between the condyles. The living sloths species of Bradypus and Choloepus do not have unequivocal anatomical features that indicate sexual dimorphism. Nevertheless, fossil sloths may have shown such dimorphism, and speculations on this subject are part of the considerations that can be made when allocating fragmentary fossils (e.g., in the new skull the presence of a long sagittal crest could indicate a male individual and the absence of an extended crest in Proeremotherium eljebe a female one). We speculate that as early as the late middle Miocene, two main lines of Megatheriinae had clearly separated in two geographic areas, one in the rising Andean area and one at low latitudes on the lowlands of central and northern South America.Fil: Carlini, Alfredo Armando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico de Paleontología de Vertebrados; ArgentinaFil: Brandoni, Diego. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; ArgentinaFil: Sánchez, Rodolfo. Museo Paleontológico de la Alcaldia de Urumaco; VenezuelaFil: Sánchez Villagra, Marcelo R.. Universitat Zurich; Suiz

Una biblioteca para almas en pena

Texto sobre el libro “Die Bibliothek der Gnade” de Thomas Lehr. Incluye obra visual del pintor Davis Birks, reproducida en blanco y negro.ITESO, A.C

Dynamics of crystalline tensionless surfaces

4 pages, 4 figures.-- PACS nrs.: 68.35.Rh, 81.10.Aj, 81.10.Bk, 81.15.Hi.We introduce a model for two-dimensional crystalline tensionless surfaces. In equilibrium, the model exhibits a roughening transition to the high temperature phase of the sine-Gordon (sG) model, though its initial stages are rougher and described by the linear molecular beam epitaxy equation; the transition temperature is about half the sG one. Depending on distance to equilibrium and temperature, the model can behave as a nonmoving flat interface, a moving interface with oscillatory roughness, or a rough moving interface. Possible experimental applications are discussed.This work has been supported by CICyT (Spain) Grant No. MAT95-0325.Publicad

Additions to the knowledge of Urumaquia robusta (Xenarthra, Phyllophaga, Megatheriidae) from the Urumaco Formation (Late Miocene), Estado Falcön, Venezuela

We describe new remains ofUrumaquia robusta Carlini, Brandoni & Sänchez, 2006, which significantly improve the knowledge of the species and allow a more precise discussion about the relationships with the rest of the South American Megatheriinae. The new remains (ulna, phalanx, femora, patella, tibia, astragalus, navicular, metatarsals IV-V) described here suggest close affinities of this taxon with the species ofPyramiodontherium and withMegatheriops rectidens, based on morphological similarities of the ulna (length, gracility), femur (general morphology, shape of the medial margin), and astragalus (angle between the discoidal and odontoid facets). In fact, the shape of femoral medial margin is a shared derived character amongUrumaquia, Pyramiodontherium andMegatheriops. However, and despite the increasing information concerning Tertiary species, their phylogenetic relationships are only partially understoo

Evaluación del tratamiento de aguas residuales con Lemna gibba en estanques con régimen de flujo de pistón

Se evaluó el comportamiento de la especie Lemna gibbaen el tratamiento del agua residual proveniente de asentamientos rurales en la región tropical andina. Se estimaronlas constantes cinéticas de primer orden para la eliminación de materia orgánica, nutrientes y bacterias. Se diseñó y construyó una estación piloto con seis estanques al aire libre, cada uno de 20 m de largo por 2 m de ancho y 0,30 m de profundidad. Se aplicó un Diseño de Bloques Completamente al Azar (DBCA) con cinco tratamientos y tres repeticiones, con diferentes tiempos de retención hidráulicos, controlados entre 2 y 11 días. Se aplicó la prueba de Tukey al 5% para evaluar posibles diferenciassignificativas entre tratamientos. La Lemna gibba se adaptórápidamente sobre el agua residual, mostrando diferenciassignificativas entre tratamientos para el rendimientomáximo de la lenteja fresca. Se obtuvieron las constantescinéticas de primer orden para dos modelos lineales diferentes,comparándose los resultados. No se encontraron valores de referencia de las constantes cinéticas bajo las mismas condiciones climáticas

Flujometría Doppler de las arterias uterinas como predictor de preeclampsia en embarazos de 18-24 semanas de gestación del hospital materno infantil del ISSEMyM en el periodo 1° de enero al 31 de diciembre del 2011.

La preeclampsia presenta una incidencia del 5-10% de los embarazos con una razón de mortalidad del 25.2% siendo la primera causa de Muerte en pacientes embarazadas a nivel mundial

Crystalline lattice effects on tensionless surface dynamics

9 pages, 5 figures.A new model is introduced for two-dimensional crystalline interfaces with negligible surface tension. The model is given by a discrete version of the linear molecular beam epitaxy (MBE) equation plus an additional term periodic in the interface height variable. Langevin dynamics simulations and analytical arguments show that the model exhibits a roughening transition to the high temperature phase of the sine-Gordon model, whose initial stages are nevertheless described by the scaling of the linear MBE equation. Out of equilibrium, the model can have three different behaviors depending on temperature and deviation from equilibrium: A non-moving flat interface, a moving interface with oscillatory roughness, and a moving interface which shows scaling. Possible connections to experiments are discussed.This work has been supported by CICyT (Spain) grant MAT95-0325.Publicad

Magnetization reversal signatures in the magnetoresistance of magnetic multilayers

Perna, P. et al.The simultaneous determination of magnetoresistance and vectorial-resolved magnetization hysteresis curves in a spin valve structure reveals distinct magnetoresistive features for different magnetic field orientations, which are directly related to the magnetization reversal processes. Measurements performed in the whole angular range demonstrate that the magnetoresistive response originates from the intrinsic anisotropic angular dependence of the magnetization orientation between the two ferromagnetic layers. This also provides direct proof that the spin-dependent scattering in the bulk of the magnetic layers is at the origin of the magnetoresistive signal. © 2012 American Physical Society.This work was supported in part by the Spanish MICINN through Project No. CSD2007-00010 and FIS 2010-18847 and by the Comunidad de Madrid through Project No. S2009/MAT-1726. P.P. acknowledges support through the Marie Curie AMAROUT EU action and the Spanish MICINN “Juan de la Cierva” contract. A.B. acknowledges support through the “Ramón y Cajal” contract from the Spanish MICINN.Peer Reviewe