Cenozoic volcanism II: the Canary Islands

[EN] The Canarian archipelago comprises seven main volcanic islands and several islets that form a chain extending for c. 500 km across the eastern Atlantic, with its eastern edge only 100 km from the NW African coast (Fig. 18.1). The islands have had a very long volcanic history, with formations over 20 million years old cropping out in the eastern Canaries. Thus all stages of the volcanic evolution of oceanic islands, including the submarine stage as well as the deep structure of the volcanoes, can be readily observed. Rainfall and vegetation cover are relatively low, with the exception of the island of La Palma, favouring both geological observation and rock preservation. Furthermore, the absence of surface water has promoted groundwater mining by means of up to 3000 km of subhorizontal tunnels (locally known as ‘galerías’).

Astronomical site testing in the era of the extremely large telescopes

The quality of astronomical sites is the first step to be considered to have the best performances from the telescopes. In particular, the efficiency of large telescopes in UV, IR, radio etc. is critically dependent on atmospheric transparency. It is well known that the random optical effects induced on the light propagation by turbulent atmosphere also limit telescope’s performances. Nowadays, clear appears the importance to correlate the main atmospheric physical parameters with the optical quality reachable by large aperture telescopes. The sky quality evaluation improved with the introduction of new techniques, new instrumentations and with the understanding of the link between the meteorological (or synoptical parameters and the observational conditions thanks to the application of the theories of electromagnetic waves propagation in turbulent medias: what we actually call astroclimatology. At the present the site campaigns are evolved and are performed using the classical scheme of optical seeing properties, meteorological parameters, sky transparency, sky darkness and cloudiness. New concept are added and are related to the geophysical properties such as seismicity, microseismicity, local variability of the climate, atmospheric conditions related to the ground optical turbulence and ground wind regimes, aerosol presence, use of satellite data. The purpose of this project is to provide reliable methods to analyze the atmospheric properties that affect ground-based optical astronomical observations and to correlate them with the main atmospheric parameters generating turbulence and affecting the photometric accuracy. The first part of the research concerns the analysis and interpretation of longand short-time scale meteorological data at two of the most important astronomical sites located in very different environments: the Paranal Observatory in the Atacama Desert (Chile), and the Observatorio del Roque de Los Muchachos(ORM) located in La Palma (Canary Islands, Spain). The optical properties of airborne dust at ORM have been investigated collecting outdoor data using a ground-based dust monitor. Because of its dryness, Paranal is a suitable observatory for near-IR observations, thus the extinction properties in the spectral range 1.00-2.30 um have been investigated using an empirical method. Furthermore, this PhD research has been developed using several turbulence profilers in the selection of the site for the European Extremely Large Telescope(E-ELT). During the campaigns the properties of the turbulence at different heights at Paranal and in the sites located in northern Chile and Argentina have been studied. This given the possibility to characterize the surface layer turbulence at Paranal and its connection with local meteorological conditions.

Development and optimization of graphic user interfaces (GUIs) for infrared spectrometers at the Telescopio Nazionale Galileo

This Phd thesis was entirely developed at the Telescopio Nazionale Galileo (TNG, Roque de los Muchachos, La Palma Canary Islands) with the aim of designing, developing and implementing a new Graphical User Interface (GUI) for the Near Infrared Camera Spectrometer (NICS) installed on the Nasmyth A of the telescope. The idea of a new GUI for NICS has risen for optimizing the astronomers work through a set of powerful tools not present in the existing GUI, such as the possibility to move automatically, an object on the slit or do a very preliminary images analysis and spectra extraction. The new GUI also provides a wide and versatile image display, an automatic procedure to find out the astronomical objects and a facility for the automatic image crosstalk correction. In order to test the overall correct functioning of the new GUI for NICS, and providing some information on the atmospheric extinction at the TNG site, two telluric standard stars have been spectroscopically observed within some engineering time, namely Hip031303 and Hip031567. The used NICS set-up is as follows: Large Field (0.25'' /pixel) mode, 0.5'' slit and spectral dispersion through the AMICI prism (R~100), and the higher resolution (R~1000) JH and HK grisms.

L’Orientalismo tra vocazione imperialista, suggestioni esotiche e omoerotiche. Le rappresentazioni storiche del passaggio tra l’epoca omayyade e abbaside.

Lo studio si tratta di mettere in evidenza il cambiamento che ha subito il termine Oriente nel secolo XX in alcuni testi della letteratura italiana contemporanea. L’opera di Edward Said, L’Orientalismo è un testo di riferimento per i nostri studi. Nel quale abbiamo focalizzato l’attenzione su alcuni aspetti salienti: il concetto di orientalismo; l’interesse nei confronti dell’Oriente sul piano politico, scientifico, letterario; l’impossibilità di separare lo studioso dalle circostanze biografiche e sociali. Siamo riusciti, quindi, a stabilire che il cambiamento dell’immagine orientale dipende da tre fattori: lo scrittore (emittente), il soggetto (la fonte) ed il lettore (destinatario), dai quali si origina l’oggetto (il testo). Basandoci su questi tre elementi abbiamo cercato di inquadrare l’interesse letterario per l’Oriente vista da una triplice prospettiva: imperialismo, fascino ed erotismo. Per studiare le prime due prospettive, abbiamo scelto due opere. La prima presenta l’immagine dell’imperialismo, si tratta di Sanya, La moglie egiziana e il Romanzo dell’Oriente Moderno (1927) di Bruno Corra. La seconda prospettiva dove troviamo l’immagine dell’Oriente fascinoso è nello scritto di Annie Vivanti, La terra di Cleopatra (1925). Il punto centrale della tesi si tratta di studiare Annie Messina (1910-1996), è una scrittrice che ha uno stile peculiare ed un approccio tutto suo al tema dell’Oriente. I testi studiati sono : "Il mirto e la rosa" (1982), "Il banchetto dell'emiro" (1997) e "La principessa e il wâlî" (1996), tutti pubblicati dalla casa editrice Sellerio.L’unico pubblicato da Mondadori è "La palma di Rusafa" (1989). L’ultima parte del lavoro abbiamo esposto un profilo storico e socio-religioso della letteratura erotica araba. In cui abbiamo rintracciato le origini dell’immagine erotico dell’Oriente e il tema dell’omosessualità, mettendo a confronto il testo omosessuale di Messina con la letteratura italiana contemporanea.

Venedig oder Rom – Disegno e Colore. Ein Topos der Kunstkritik und seine Folgen

Partendo dal concetto di 'regionalismo' oppure d' identità regionale nell'interpretazione che ne ha dato Fernand Braudel ci rendiamo conto che il modo di guardare Venezia e l'arte veneziana con una certa ottica si forma a partire del romanticismo. Sono autori quali John Ruskin e Hippolyte Taine che sulla base della teoria del 'milieu' hanno dato inizio a un metodo della storia dell'arte ottocentesca che identifica il carattere del luogo e della sua gente con l'arte che vi viene prodotta. Il concetto teorico che sta alla base di questo modo di interpretare la pittura, deriva però dal Vasari e si riferiva all'opposizione artistica tra Venezia e Firenze, e al loro antagonismo che secondo Vasari vedeva vincitore il disegno. Dopo Vasari questo concetto viene ripreso da altri teorici italiani, ma all'inizio del Settecento il dibattito si sposta in Francia dove de Piles sulla scia del 'debat des anciens et modernes' dando la palma a Rubens invece di Poussin, prende la parte del colore. Grazie alla diffusione del nuovo gusto per il colore che si diffonde dalla Francia per tutta l'Europa, l'arte veneziana acquista una grandissima riputazione dalla quale approfittano soprattutto i pittori moderni veneziani attivi all'estero, durante il Settecento. Davanti questo sfondo viene sottolineata l'importanza di Venezia per il giovane Mengs che deve il suo primo successo al 'ritratto a pastelli', seguendo il gusto del sovrano sassone Augusto III. A causa dell'incarico per il quadro della chiesa cattolica di Dresda il pittore si porta a Venezia dove studia l'Assunta di Tiziano che si rispecchia nel quadro per Dresda. Dall'incontro con l'arte di Tiziano nasce un intenso dialogo teorico con la sua pittura di modo che Tiziano viene incluso da Mengs nella 'trias' dei tre primi pittori della storia della pittura per la perfezione del suo colore. Tale rivalutazione di Tiziano, pubblicata nei suoi scritti, porta alla revisione generale dei pregiudizi accademici verso la scuola veneziana sul livello teorico e pratico. A Venezia è Andrea Memmo, basandosi sui scritti di Mengs, a dare con la sua 'Orazione' davanti l'Accademia nel 1787 una nuova visione quando abbandona la tradizionale gerarchia 'disegno, colore e chiaroscuro' e con essa anche la tradizionale classifica delle scuole. Angelika Kauffmann che ritrae Memmo durante il suo soggiorno veneziano rappresenta forse il tipo di pittura che Memmo intese come ideale ed è una pittura che riunisce le qualità dei grandi maestri del passato facendolo confluire in un gusto universale. Spetterà poi al Lanzi di introdurre l'idea di una nuova pittura di carattere nazionale che si verifica durante l'Ottocento con i 'Macchiaioli' che danno la prevalenza al colore e non al disegno.

Geochemistry, fluxes and nitrogen isotopic composition data of traps LP1 and EBC2-1 and cores GeoB4242-4 and Geo4301-1

We compare total and biogenic particle fluxes and stable nitrogen isotope ratios (d15N) at three mooring sites along a productivity gradient in the Canary Islands region with surface sediment accumulation rates and sedimentary d15N. Higher particle fluxes and sediment accumulation rates, and lower d15N were observed in the upwelling influenced eastern boundary region (EBC) compared to the oligotrophic sites north of Gran Canaria [European Station for Time-Series in the Ocean, Canary Islands (ESTOC]] and north of La Palma (LP). The impact of organic matter degradation and lateral particle advection on sediment accumulation was quantified with respect to the multi-year flux record at the ESTOC. Remineralisation of organic matter in the water column and at the sediment surface resulted in an organic carbon preservation of about 0.8% and total nitrogen preservation of about 0.4% of the estimated export production. Higher total and carbonate fluxes and accumulation rates in the lower traps and surface sediment compared to the upper traps indicated that at least 50% of the particulate matter at the ESTOC was derived from allochthonous sources. Low d15N values in the lower traps of the ESTOC and LP point to a source region influenced by coastal upwelling. We conclude from this study that the reconstruction of export production or nutrient regimes from sedimentary records in regions with strong productivity gradients might be biased due to the mixture of particles originating from autochthonous and allochthonous sources. This could result in an imprint of high productivity signatures on sedimentation processes in oligotrophic regions.

Investigation of time series stations along a productivity gradient north of the Canary Islands

Three stations along a productivity gradient north of the Canary Islands were investigated for surface-water properties, particle flux, and composition (biogenic and lithogenic components, and stable nitrogen isotope composition, delta15N) and export production. Investigation sites along the east-west transect off the NW African upwelling margin included the European Station for Time-Series in the Ocean, Canary Islands (ESTOC), one location contiguous to the NW African upwelling zone in the Eastern Boundary Current (EBC) and one station north of the island La Palma (LP). The seasonality of surface-water properties along the transect was mainly influenced by the winter cooling and simultaneous phytoplankton maximum and, in addition at EBC, by nearby upwelling. Accordingly, particle flux and composition along the transect were closely linked to the winter bloom sedimentation and upwelling related enhanced plankton biomass stemming from the primary upwelling and the Cape Yubi filament at EBC. During all seasons, particle flux was highest at EBC and had the highest contribution of biogenic opal and lithogenic components, and the lowest delta15N compared to the offshore stations. But contrary to what would be expected from the productivity gradient, particle flux did not decrease from ESTOC to LP. Below the upper several hundred meters, particle flux was enhanced by additional particle input along the entire transect, manifested by an increase of flux with depth and lower delta15N values. We offer a scenario in which intermediate nepheloid layers originating from the primary upwelling as well as particle dispersion from upwelling filaments, mainly the Cape Ghir filament, impact on the trap stations as far as 700 km into the open ocean. This study contributes to our understanding of the poorly resolved biogeochemical transition between the productive shelf and subtropical gyre provinces.

Probabilistic versus incremental presynaptic learning in biological plausible synapses

In this paper, the presynaptic rule, a classical rule for hebbian learning, is revisited. It is shown that the presynaptic rule exhibits relevant synaptic properties like synaptic directionality, and LTP metaplasticity (long-term potentiation threshold metaplasticity). With slight modifications, the presynaptic model also exhibits metaplasticity of the long-term depression threshold, being also consistent with Artola, Brocher and Singer’s (ABS) influential model. Two asymptotically equivalent versions of the presynaptic rule were adopted for this analysis: the first one uses an incremental equation while the second, conditional probabilities. Despite their simplicity, both types of presynaptic rules exhibit sophisticated biological properties, specially the probabilistic version

On the Biological Plausibility of Artificial Metaplasticity

The training algorithm studied in this paper is inspired by the biological metaplasticity property of neurons. Tested on different multidisciplinary applications, it achieves a more efficient training and improves Artificial Neural Network Performance. The algorithm has been recently proposed for Artificial Neural Networks in general, although for the purpose of discussing its biological plausibility, a Multilayer Perceptron has been used. During the training phase, the artificial metaplasticity multilayer perceptron could be considered a new probabilistic version of the presynaptic rule, as during the training phase the algorithm assigns higher values for updating the weights in the less probable activations than in the ones with higher probability

A Prediction Model to Diabetes using Artificial Metaplasticity

Diabetes is the most common disease nowadays in all populations and in all age groups. Different techniques of artificial intelligence has been applied to diabetes problem. This research proposed the artificial metaplasticity on multilayer perceptron (AMMLP) as prediction model for prediction of diabetes. The Pima Indians diabetes was used to test the proposed model AMMLP. The results obtained by AMMLP were compared with other algorithms, recently proposed by other researchers, that were applied to the same database. The best result obtained so far with the AMMLP algorithm is 89.93%

On the monitoring of surface displacement in connection with volcano reactivation in Tenerife, Canary Islands, using space techniques

Geodetic volcano monitoring in Tenerife has mainly focused on the Las Cañadas Caldera, where a geodetic micronetwork and a levelling profile are located. A sensitivity test of this geodetic network showed that it should be extended to cover the whole island for volcano monitoring purposes. Furthermore, InSAR allowed detecting two unexpected movements that were beyond the scope of the traditional geodetic network. These two facts prompted us to design and observe a GPS network covering the whole of Tenerife that was monitored in August 2000. The results obtained were accurate to one centimetre, and confirm one of the deformations, although they were not definitive enough to confirm the second one. Furthermore, new cases of possible subsidence have been detected in areas where InSAR could not be used to measure deformation due to low coherence. A first modelling attempt has been made using a very simple model and its results seem to indicate that the deformation observed and the groundwater level variation in the island may be related. Future observations will be necessary for further validation and to study the time evolution of the displacements, carry out interpretation work using different types of data (gravity, gases, etc) and develop models that represent the island more closely. The results obtained are important because they might affect the geodetic volcano monitoring on the island, which will only be really useful if it is capable of distinguishing between displacements that might be linked to volcanic activity and those produced by other causes. One important result in this work is that a new geodetic monitoring system based on two complementary techniques, InSAR and GPS, has been set up on Tenerife island. This the first time that the whole surface of any of the volcanic Canary Islands has been covered with a single network for this purpose. This research has displayed the need for further similar studies in the Canary Islands, at least on the islands which pose a greater risk of volcanic reactivation, such as Lanzarote and La Palma, where InSAR techniques have been used already.

GIS analysis of the accuracy of Tomas Lopez's historical cartography in the Canary Islands (1742 - 1746)

The accuracy of Tomás López´s historical cartography of the Canary Islands included in the “Atlas Particular” of the Kingdoms of Spain, Portugal and Adjacent Islands” is analyzed. For this purpose, we propose a methodology based on Geographic Information Systems (GIS), a comparison of digitized historical cartography population centres with current ones. This study shows that the lineal error value is small for the smaller islands: Lanzarote, El Hierro, La Palma and La Gomera. In the large islands of Tenerife, Fuerteventura and Gran Canaria, the error is smaller in central zones but increases towards the coast. This indicates that Tomás López began his cartography starting from central island zones, accumulating errors due to lack of geodetic references as he moved toward the coast.

Simulating accepting networks of evolutionary processors with filtered connections by accepting evolutionary P systems

In this work, we propose a variant of P system based on the rewriting of string-objects by means of evolutionary rules. The membrane structure of such a P system seems to be a very natural tool for simulating the filters in accepting networks of evolutionary processors with filtered connections. We discuss an informal construction supporting this simulation. A detailed proof is to be considered in an extended version of this work.

Un'idea nel palmo di una mano = An idea in the palm of a hand

Una idea en la palma de una mano. Texto en italiano e inglés.

Anteproyecto de camino forestal "Cumbre Vieja al Llanito" tramo 1º

El camino forestal que en la propuesta del estudio se denomina "Cumbre Vieja al Llanito" cuya primera parte esta proyectada y cuya segunda es objeto de este anteproyecto; esta destinado a recoger los productos de la mas extensa zona posible de montes publicos y particulares de la ladera oriental en su mitad meridional de la Isla de La Palma.