A New Recursive Least-Squares Method with Multiple Forgetting Schemes

We propose a recursive least-squares method with multiple forgetting schemes to track time-varying model parameters which change with different rates. Our approach hinges on the reformulation of the classic recursive least-squares with forgetting scheme as a regularized least squares problem. A simulation study shows the effectiveness of the proposed method

Vascularization of the trachea in the bottlenose dolphin: Comparison with bovine and evidence for evolutionary adaptations to diving

The rigid structure of the mammalian trachea is functional to maintain constant patency and airflow during breathing, but no gas exchange takes place through its walls. The structure of the organ in dolphins shows increased rigidity of the tracheal cartilaginous rings and the presence of vascular lacunae in the submucosa. However, no actual comparison was ever made between the size and capacity of the vascular lacunae of the dolphin trachea and the potentially homologous structures of terrestrial mammals. In the present study, the extension of the lacunae has been compared between the bottlenose dolphin and the bovine, a closely related terrestrial Cetartiodactyla. Our results indicate that the extension of the blood spaces in the submucosa of dolphins is over 12 times larger than in the corresponding structure of the bovines. Furthermore, a microscopic analysis revealed the presence of valve-like structures in the walls of the cetacean lacunae. The huge difference in size suggests that the lacunae are not merely a product of individual physiological plasticity, but may constitute a true adaptive evolutionary character, functional to life in the aquatic environment. The presence of valve-like structures may be related to the regulation of blood flow, and curtail excessive compression under baric stress at depth

Poder monetário e financeiro dos países do BRICS: o que mudou desde a crise financeira global de 2008 e por que é importante

This paper analyses the ongoing transformations in the international monetary and financial system and the role played by the BRICS countries. It argues that while the changes the BRICS countries triggered have been marginal, because there was not a substantial change in the underlying power relations, these changes matter because they are forms of power. It looks into three areas where the group was relatively successful in challenging the system: (i) increasing their voice in major global economic forums (focusing on the IMF and the G20), (ii) creating new international financial institutions and (iii) influencing the IMF’s new institutional view on capital flows. It then discusses the limits of the BRICS’ monetary and financial power given their subordinated position in the currency hierarchy, China being the exception. Understanding the rise and limitations of the BRICS’ monetary and financial power is important because they challenge the existing theoretical framework to advance if it wants to understand how emerging market and developing economies, and the groupings formed by them, act in order to uphold their interests in a system which is rigid, hierarchical and still dominated by advanced economies.Este artigo analisa as transformações em curso no sistema monetário e financeiro internacional (SMFI) desde a Crise Financeira Global de 2008 e o papel desempenhado pelos países do BRICS. O artigo argumenta que, embora as mudanças provocadas pelos países do BRICS tenham sido marginais, porque não ocorreu uma mudança substancial nas relações de poder subjacentes, estas mudanças importam porque são poder como um fim em si mesmo. São examinadas três áreas em que o grupo foi relativamente bem sucedido em desafiar o sistema: (i) aumentar sua voz nos principais fóruns econômicos globais (com foco no FMI e no G20), (ii) criar novas instituições financeiras internacionais; e (iii) influenciar a nova visão institucional do FMI sobre fluxos de capital. Em seguida, discute-se os limites do poder monetário e financeiro dos BRICS, dada sua posição subordinada no SMFI, com a exceção da China. Compreender a ascensão e os limites do poder monetário e financeiro dos BRICS é importante porque eles encorajam o arcabouço teórico existente a avançar, se quisermos entender como atores subordinados – como as economias emergentes e os grupos formados por eles (tal qual os BRICS) – podem conseguir aquilo que querem em um sistema rígido, hierárquico e ainda dominado pelas economias avançadas

Functionalisation of surfaces and interfaces : molecules, particles and crystals

This thesis is concerned with understanding and directing the functionalisation of solid surfaces with materials: molecules, nanoparticles and crystals. Both conducting (electrode) and insulating surfaces are of interest. For molecular functionalisation, a sweep potential procedure has been developed to assist the formation of self assembled monolayers (SAMs) of a ruthenium thiolated complex. Electrochemical investigations were employed to characterised the SAM formed on a platinum electrode. Nanoparticles formation explored two distinct routes. First Pd nanoparticles were successfully formed within ultra-thin Nafion films via impregnation and a chemical reduction method. Morphological investigations utilised atomic force microscopy. The electrocatalytic properties of the nanocomposite material were elucidated for the hydrogen oxidation reaction. The methodology used for the preparation of this nanocomposite material shows promise for applications in sensors and fuel cells. Second, the potential-assisted deposition of pre–formed perthiolated-ß-cyclodextrin-capped Pt nanoparticles method is described. Pt nanoparticles (5 nm diameter) were deposited in a controlled fashion on indium tin oxide and highly oriented pyrolytic graphite electrodes. The Pt anoparticles formed in this way were electrocatalytically active towards hydrogen generation and oxidation. This new approach for the deposition of metal nanoparticles with controlled surface density provides a new tool for the investigation of electrocatalytic processes. A major focus of the second part of the thesis has been the development of methods to study crystal deposition at extreme supersaturation. For this purpose a delivery system for calcium carbonate at high-supersaturation ion has been coupled with a quartz crystal microbalance and in–situ optical microscopy. The dynamics and quantitative evaluation of calcium carbonate deposition onto foreign solid substrates, and the effect of various additives, are described. Ex– situ studies, scanning electron microscopy and microRaman spectroscopy, allowed the morphological characterisation of the phases deposited. The transformation of ACC to calcite has been explored in details. In the study of additives, a significant finding was that citrate concentration shows a nonmonotonic behaviour on the amount of scale deposited. Fast screening of different additives (polymeric and molecular) and a quantitative ranking of their inhibitory properties on calcium carbonate deposition on a gold surface is described. Molecular and polymeric additives showed different inhibitory mechanisms on the scaling process and the technique employed gave a better insight into their mode of action

Back to Water: Signature of Adaptive Evolution in Cetacean Mitochondrial tRNAs

Abstract The mitochondrion is the power plant of the eukaryotic cell, and tRNAs are the fundamental components of its translational machinery. In the present paper, the evolution of mitochondrial tRNAs was investigated in the Cetacea, a clade of Cetartiodactyla that retuned to water and thus had to adapt its metabolism to a different medium than that of its mainland ancestors. Our analysis focussed on identifying the factors that influenced the evolution of Cetacea tRNA double-helix elements, which play a pivotal role in the formation of the secondary and tertiary structures of each tRNA and consequently manipulate the whole translation machinery of the mitochondrion. Our analyses showed that the substitution pathways in the stems of different tRNAs were influenced by various factors, determining a molecular evolution that was unique to each of the 22 tRNAs. Our data suggested that the composition, AT-skew, and GC-skew of the tRNA stems were the main factors influencing the substitution process. In particular, the range of variation and the fluctuation of these parameters affected the fate of single tRNAs. Strong heterogeneity was observed among the different species of Cetacea. Finally, it appears that the evolution of mitochondrial tRNAs was also shaped by the environments in which the Cetacean taxa differentiated. This latter effect was particularly evident in toothed whales that either live in freshwater or are deep divers

Messi all’angolo

Il laboratorio che abbiamo preparato assieme ai ragazzi della IID e della IIE della Scuola Media “Tomizza” è stata la nostra prima esperienza nel mondo di “La matematica dei ragazzi”. Quello che possiamo affermare con sicurezza è che il nostro rapporto con gli alunni è cambiato: abbiamo lavorato in sinergia per un progetto comune e il risultato ha sorpreso sia noi che loro. Tutto è cominciato quando Eva Onofrio ci ha invitate a partecipare alla prima riunione del Nucleo di Ricerca Didattica dell’Università di Trieste. Sinceramente, all’inizio ci siamo sentite un po’ spaesate perché quel tipo di metodologia didattica era per noi una novità assoluta. Certamente, confidavamo nella spigliatezza dei nostri alunni come oratori; avevamo però qualche dubbio sull’argomento da proporre, che non volevamo fosse banale, ma nemmeno troppo ostico per i ragazzi. Abbiamo riletto tutte i volumi delle edizioni precedenti, scartando di volta in volta gli argomenti già trattati; poi l’ispirazione è arrivata per caso, mentre prendevamo in considerazione il progetto “Vela sul Mare”. I ragazzi delle classi seconde medie del nostro Istituto partecipano ormai da anni a questo progetto. Esperti della Lega Navale tengono delle lezioni teorico-pratiche di nautica e navigazione a vela. Una delle lezioni più complesse è quella relativa alle carte nautiche: il concetto di punto nave, di latitudine, di longitudine, e da qui il passo è stato breve… l’angolo! Parliamo dell’angolo

Nanoscale intermittent contact-scanning electrochemical microscopy

A major theme in scanning electrochemical microscopy (SECM) is a methodology for nanoscale imaging with distance control and positional feedback of the tip. We report the expansion of intermittent contact (IC)-SECM to the nanoscale, using disk-type Pt nanoelectrodes prepared using the laser-puller sealing method. The Pt was exposed using a focused ion beam milling procedure to cut the end of the electrode to a well-defined glass sheath radius, which could also be used to reshape the tips to reduce the size of the glass sheath. This produced nanoelectrodes that were slightly recessed, which was optimal for IC-SECM on the nanoscale, as it served to protect the active part of the tip. A combination of finite element method simulations, steady-state voltammetry and scanning electron microscopy for the measurement of critical dimensions, was used to estimate Pt recession depth. With this knowledge, the tip-substrate alignment could be further estimated by tip approach curve measurements. IC-SECM has been implemented by using a piezo-bender actuator for the detection of damping of the oscillation amplitude of the tip, when IC occurs, which was used as a tip-position feedback mechanism. The piezo-bender actuator improves significantly on the performance of our previous setup for IC-SECM, as the force acting on the sample due to the tip is greatly reduced, allowing studies with more delicate tips. The capability of IC-SECM is illustrated with studies of a model electrode (metal/glass) substrate

Coherent Dynamics in Solutions of Colloidal Plexcitonic Nanohybrids at Room Temperature

The increasing ability to prepare systems with nanoscale resolution and address their optical properties with ultrashort time precision is revealing quantum phenomena with tremendous potential in quantum nanotechnologies. Colloidal plexcitonic materials promise to play a pivotal role in this scenario. Plexcitons are hybrid states originating from the mixing of the plasmon resonances of metal nanostructures with molecular excitons. They allow nanoscale confinement of electromagnetic fields and the establishment of strong couplings between light and matter, potentially giving rise to controllable and tunable coherent phenomena. However, the characterization of the ultrafast coherent and incoherent dynamics of colloidal plexciton nanohybrids remains highly unexplored. Here, two dimensional electronic spectroscopy (2DES) is employed to study the quantum coherent interactions active after the photoexcitation of these systems. By comparing the response of the nanohybrids with the one of the uncoupled systems, the nonlinear photophysical processes at the base of the coherent dynamics are identified, allowing a step forward toward the effective understanding and exploitation of these nanomaterials

Information Asymmetries, Family Ownership and Divestiture Financial Performance: Evidence from Western European Countries

Abstract: Combining agency theory and information asymmetry literature this paper examines the controversial relationship between family ownership and the stock market reaction to a divestiture event. We employ a unique dataset of 265 divestiture transactions in West European countries. We reveal that in presence of high information asymmetries the stock market’s positive reaction will be lowered by a higher perception of the risk of opportunistic behaviours that controlling owners may carry out to the detriment of minority shareholders