Quaternary glacial evolution in the Central Cantabrian Mountains (Northern Spain)

Peer reviewedPostprin

Cambios en la vegetación producidos por los hormigueros de Lasius flavus en pastos supraforestales del pirineo occidental

7 páginasPara averiguar los cambios en la vegetación debidos a la presencia de montículos de tierra producidos por la hormiga Lasius flavus, se llevaron a cabo muestreos dentro y fuera de hormigueros seleccionados al azar. Diez pares de muestras se tomaron en cada una de las comunidades de pasto Bromion erecti y Nardion strictae en el Pirineo occidental. Se determinó la cobertura de especies, y el N total, pH y temperatura del suelo. En general las especies que colonizan los hormigueros no son diferentes de las que se encuentran en su entorno, pero cambia su abundancia. Thymus praecox, Cerastium arvense y Calluna vulgaris fueron las únicas especies significativamente más abundantes en los hormigueros que en el pasto contiguo. En general aumentan las especies termófilas y disminuyen las calcífugas (p.e. Nardus stricta), al presentar los hormigueros una mayor alcalinidad. El número de especies es menor en los hormigueros que fuera de ellos, pero estos contribuyen a aumentar la heterogeneidad ambiental general de la comunidad.Peer reviewe

A simple test of momentum in foreign exchange markets

This study proposes a new method for testing for the presence of momentum in nominal exchange rates, using a probabilistic approach. We illustrate our methodology estimating a binary response model using information on local currency / US dollar exchange rates of eight emerging economies. After controlling for important variables a§ecting the behavior of exchange rates in the short-run, we show evidence of exchange rate inertia; in other words, we Önd that exchange rate momentum is a common feature in this group of emerging economies, and thus foreign exchange traders participating in these markets are able to make excess returns by following technical analysis strategies. We Önd that the presence of momentum is asymmetric, being stronger in moments of currency depreciation than of appreciation. This behavior may be associated with central bank intervention.Momentum, foreign exchange markets, hazard duration analysis, emerging economies.

El quijotismo intrahistórico de Unamuno.

Sin resume

Epifisiolisis proximal del fémur en valgo: aportación de dos casos

Los autores describen dos pacientes con deslizamiento epifísario en valgo de la extremidad proximal del fémur (epifisiolisis). Este desplazamiento lateral del núcleo epifísario es muy raro habiendo sido publicados muy pocos casos. El diagnóstico se puede efectuar con las proyecciones radiográficas de Leuenstain o una verdadera lateral. Las radiografías anteroposteriores de la cadera practicadas se evaluaron como normales y la línea de Klein no es de utilidad en estos casos pues corta la porción superior del núcleo epifísario como en las caderas normales del niño.The authors present two patients with reverse slipped capital femoral epiphysis. The lateral displacement is very rare and only few cases has been reported in the literature. The Lauenstain's image and/or a true lateral roentgenographic view of the hip allowed the diagnosis. The anteroposterior XRay image were evaluated as normal and the condition was not recognized because the Klein line passes through the superior corner of the epiphysis as in the normal hip

The "Ñireco Caldera" in the central-western Neuquén Andes (38°50'S - 70°50'O)

In the southern segment of the Copahue- Pino Hachado block, next to the Moquehue-Alumine lacustrine basin, an anomalous concentration of calderas, resulting from a Pliocene-Quaternary volcanic activity was recognized. The Ñireco caldera, which was proposed as part of this caldera complex, is the reason of the present work. The authors object the interpretation of such a morphostructural feature on the basis of a detailed geomorphologic, structural and stratigraphic analyses of the area. The limits of the proposed caldera coincide mostly with fluvial valleys that seem to be controlled by previous structures like faults and regional lineaments. There are no evidences that could suggest the presence of a volcanic complex that theoretically contains such a depression, or for its external and internal flanks. The central sector of the proposed caldera presents the highest altitude values of the region (± 2,900 m a.s.l.), which highly surpass those of the Principal Cordillera at these latitudes. The local stratigraphy of the area, is dominated by the oldest rocks of the region (Upper Paleozoic granitoids and Triassic volcanic and volcaniclastic sequences), and shows not temporal coincidence with the Pliocene-Quaternary volcanic activity, well represented immediately to the north. The study area falls on the contrary into a thick-skinned west-verging fold-and-thrust-belt, where tectonic inversion played a central role.Fil:García Morabito, E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina