La macroflora oligocena de la cuenca de Cervera, Lérida, España (Colección del Museu Comarcal de Cervera)

This paper is the follow-up of another study of the Oligocene macroflora from Cervera (Ebro Basin, Spain), started with the 'Madern Collection' from the Museu de Geologia de Barcelona (Sanz de Siria, 1992). The present paper analyses 226 specimen from the Museu Comarcal de Cervera. 29 species, not mentioned before, are included and 3 new species of the tertiary flora are established. A likely model of the vegetation existing in the area in the low Oligocene is established by comparision with the models existing today of similar content and structure. Similar models are presently located in tropical regions between 15o and 25o latitude north. The main vegetal community that has been found correspond to the tropical deciduous forest. In upper, wetter levels, evergreen forest with laurisilva communities appear. The climate in the low Oligocene in the region was probably of the tropicalk kind, with a long dry period followed by a rain period. The average temperature would be around 22o-26o. Key words: Paleobotany, Macroflora, Oligocene, Paleoecology, Ebro Basin, Cervera, Spain, Museu Comarcal de Cervera.En el presente trabajo se prosigue el estudio de la flora oligocena de Cervera (Lérida, España) iniciado con la 'Colección Madern' del Museu de Geologia de Barcelona (Sanz de Siria, 1992). Se estudian ahora 226 ejemplares depositados en el Museu Comarcal de Cervera. Se menciona la presencia de 29 especies no citadas anteriormente y se crean 3 especies nuevas para la flora terciaria. Asimismo, se determina el posible modelo de vegetación existente en la zona durante el Oligoceno, por comparación con los modelos actuales de parecida composición y estructura. Modelos similares se localizan actualmente en regiones tropicales, entre los 15o y los 25o de latitud Norte. La principal comunidad vegetal encontrada corresponde a bosques tropicales deciduos. En niveles superiores más húmedos aparecen bosques perennifolios de tipo laurisilva. El clima de la región, durante el Oligoceno inferior, parece que fue de tipo tropical, con una estación seca prolongada seguida de un período de lluvias. Las temperaturas medias anuales podrían situarse entre los 22o-26o. Palabras clave: Paleobotánica, Macroflora, Oligoceno, Paleoecología, Cuenca del Ebro, España, Museu Comarcal de Cervera

Dynamical Backaction Cooling with Free Electrons

The ability to cool single ions, atomic ensembles, and more recently macroscopic degrees of freedom down to the quantum groundstate has generated considerable progress and perspectives in Basic and Technological Science. These major advances have been essentially obtained by coupling mechanical motion to a resonant electromagnetic degree of freedom in what is generally known as laser cooling. In this work, we experimentally demonstrate the first self-induced coherent cooling mechanism that is not mediated by the electromagnetic field. Using a focused electron beam, we report a 50-fold reduction of the motional temperature of a nanowire. Our result primarily relies on the sub-nanometer confinement of the electron beam and generalizes to any delayed and topologically confined interaction, with important consequences for near-field microscopy and fundamental nanoscale dissipation mechanisms.Comment: 8 pages, 4 figure

Estudio paleoecológico y paleoclimático de la macroflora oligocena de Cervera (Lleida, España)

After the taxonomic revision of the macroflora from Cervera (Lleida, Spain) of the 'Martí Madern' (Museu de Geologia de Barcelona and Museu Comarcal de Cervera collections). We present here their palaeoecological and palaeoclimatic study. A likely model of the vegetation existing in the area in the low Oligocene is established by comparison with the models existing today of similar content and structure. Similar models are presently located in tropical regions about 20o latitude North. The main vegetal community that has been found corresponds to the tropical deciduous forest. In superior wetter levels, evergreen forest with laurisilva communities appears. The climate in the early Oligocene in the region was probably of the tropical kind, with a long dry period followed by a rain period. The average temperature would be around 22o - 26o. Key words: Palaeobotany, Macroflora, Oligocene, Palaeoecology, Palaeoclimatology, Ebro Basin, Cervera, Spain.Este trabajo es continuación de las revisiones taxonómicas realizadas de las colecciones de macroflora fósil 'Martí Madern', del Museu se Geologia de Barcelona y del Museu Comarcal de Cervera. Partiendo del estudio del conjunto de taxones fósiles hallado, se obtienen datos paleoecológicos y paleoclimáticos acerca de la cuenca y se intenta establecer el modelo de vegetación que debió existir durante el Oligoceno en esa zona. La principal comunidad vegetal presente correspondió a bosques deciduos de tipo tropical. En niveles superiores se ubicaron bosques perennifolios semejantes a las actuales laurisilvas. El clima en la región en el Oligoceno inferior fue de tipo tropical, con una estación seca prolongada a la que seguía un período de lluvias. Las temperaturas medias podían situarse en torno a los 22o-26o. Palabras clave: Paleobótanica, Macroflora, Oligoceno, Paleoecología, Paleoclimatología, Cuenca del Ebro, Cervera, España

Giant slip lengths of a simple fluid at vibrating solid interfaces

It has been shown recently [PRL 102, 254503 (2009)] that in the plane-plane configuration a mechanical resonator vibrating close to a rigid wall in a simple fluid can be overdamped to a frozen regime. Here, by solving analytically the Navier Stokes equations with partial slip boundary conditions at the solid fluid interface, we develop a theoretical approach justifying and extending these earlier findings. We show in particular that in the perfect slip regime the above mentioned results are, in the plane-plane configuration, very general and robust with respect to lever geometry considerations. We compare the results with those obtained previously for the sphere moving perpendicularly and close to a plane in a simple fluid and discuss in more details the differences concerning the dependence of the friction forces with the gap distance separating the moving object (i.e., plane or sphere) from the fixed plane. Finally, we show that the submicron fluidic effect reported in the reference above, and discussed further in the present work, can have dramatic implications in the design of nano-electromechanical systems (NEMS).Comment: submitted to PRE (see also PRL 102, 254503 (2009)

Modelos de nichos potenciales de especies de interés para tomadores de decisión, y su relación con el cambio climático en Nicaragua y América Central

DOI: 10.5377/encuentro.v41i84.51Encuentro 2009/ Año XLI, N° 84, 62-80DOI: 10.5377/encuentro.v41i84.51Encuentro 2009/ Año XLI, N° 84, 62-8

Universal Vectorial and Ultrasensitive Nanomechanical Force Field Sensor

Miniaturization of force probes into nanomechanical oscillators enables ultrasensitive investigations of forces on dimensions smaller than their characteristic length scale. Meanwhile it also unravels the force field vectorial character and how its topology impacts the measurement. Here we expose an ultrasensitive method to image 2D vectorial force fields by optomechanically following the bidimensional Brownian motion of a singly clamped nanowire. This novel approach relies on angular and spectral tomography of its quasi frequency-degenerated transverse mechanical polarizations: immersing the nanoresonator in a vectorial force field does not only shift its eigenfrequencies but also rotate eigenmodes orientation as a nano-compass. This universal method is employed to map a tunable electrostatic force field whose spatial gradients can even take precedence over the intrinsic nanowire properties. Enabling vectorial force fields imaging with demonstrated sensitivities of attonewton variations over the nanoprobe Brownian trajectory will have strong impact on scientific exploration at the nanoscale

Using mid-infrared spectroscopy and supervised machine-learning to identify vertebrate blood meals in the malaria vector, Anopheles arabiensis

Background: The propensity of diferent Anopheles mosquitoes to bite humans instead of other vertebrates infuences their capacity to transmit pathogens to humans. Unfortunately, determining proportions of mosquitoes that have fed on humans, i.e. Human Blood Index (HBI), currently requires expensive and time-consuming laboratory procedures involving enzyme-linked immunosorbent assays (ELISA) or polymerase chain reactions (PCR). Here, midinfrared (MIR) spectroscopy and supervised machine learning are used to accurately distinguish between vertebrate blood meals in guts of malaria mosquitoes, without any molecular techniques. Methods: Laboratory-reared Anopheles arabiensis females were fed on humans, chickens, goats or bovines, then held for 6 to 8 h, after which they were killed and preserved in silica. The sample size was 2000 mosquitoes (500 per host species). Five individuals of each host species were enrolled to ensure genotype variability, and 100 mosquitoes fed on each. Dried mosquito abdomens were individually scanned using attenuated total refection-Fourier transform infrared (ATR-FTIR) spectrometer to obtain high-resolution MIR spectra (4000 cm−1 to 400 cm−1 ). The spectral data were cleaned to compensate atmospheric water and CO2 interference bands using Bruker-OPUS software, then transferred to Python™ for supervised machine-learning to predict host species. Seven classifcation algorithms were trained using 90% of the spectra through several combinations of 75–25% data splits. The best performing model was used to predict identities of the remaining 10% validation spectra, which had not been used for model training or testing. Results: The logistic regression (LR) model achieved the highest accuracy, correctly predicting true vertebrate blood meal sources with overall accuracy of 98.4%. The model correctly identifed 96% goat blood meals, 97% of bovine blood meals, 100% of chicken blood meals and 100% of human blood meals. Three percent of bovine blood meals were misclassifed as goat, and 2% of goat blood meals misclassifed as human. Conclusion: Mid-infrared spectroscopy coupled with supervised machine learning can accurately identify multiple vertebrate blood meals in malaria vectors, thus potentially enabling rapid assessment of mosquito blood-feeding histories and vectorial capacities. The technique is cost-efective, fast, simple, and requires no reagents other than desiccants. However, scaling it up will require field validation of the findings and boosting relevant technical capacity in affected countries