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

Asymmetric Hydrogenation of 1-alkyl and 1-aryl vinyl benzoates: a broad scope procedure for the highly enantioselective synthesis of 1-substituted ethyl benzoates

The enantioselective hydrogenation of enol esters of formula CH2=C(OBz)R with rhodium catalysts based on phosphine-phosphite ligands (P-OP) has been studied. The reaction has a broad scope and it is suitable for the preparation of products possessing a wide variety of R substituents. For the cases where R is a primary alkyl high catalyst activity (S/C = 500) and enantioselectivities (95-99 % ee) were obtained with a catalyst characterized by an ethane backbone and a PPh2 fragment. In contrast, for R = tBu a catalyst possessing a benzene backbone provided the best results (97 % ee). Derivatives with a cycloalkyl R substituent were particularly difficult substrates for this reaction. A broader catalyst screening was required for these substrates, which identified a catalyst possessing a P(m-xylyl)2 fragment as the most appropriate one, affording enantioselectivities between 90 and 95 % ee. Outstanding enantioselectivities (99 % ee) and high catalyst activity (S/C = 500-1000) were also obtained in the case of substrates bearing a Ph or a fluoroaryl R substituent. In addition, the system is also appropriate for the preparation of other synthetically useful esters as those for R = benzyl, 2-phenylethyl or Nphthalimido alkyl chains. Likewise, the hydrogenation of divinyl dibenzoates proceeded with very high diastero- and enantioselectivity, generating rather low amounts of the meso isomer (3-6 %). On the other hand, substrates with Br- and MeO- substituents at the phenyl benzoate ring, suitable for further functionalization, have also been examined. The results obtained indicate no detrimental effect of these substituents in the hydrogenation. Alternatively, the methodology has been applied to the highly enantioselective synthesis of deuterium isotopomers of 1-octyl benzoate bearing CDH2, CD2H or CD3 fragments. Finally, as a practical advantage of the present system, it has been observed that the high performance of the catalysts is retained in high concentrated solutions or even in the neat substrate, then minimizing both the amount of solvent added and the volume of the reactionJunta de Andalucía 2009/FQM-4832CSIC 201480E03 1Ministerio de Ciencia e Innovación CTQ2010- 14796/BQ