488 research outputs found

    The effects of claw regeneration on territory ownership and mating success in the fiddler crab Uca mjoebergi

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    Underlying male quality is often reflected in the condition of sexually selected traits. In fiddler crabs, male success in both intra- and interspecific interactions is highly dependent on the size of the major claw. However, males are often forced to autotomize their major claw. Claw regeneration significantly altered the structure of a males' major claw in Uca mjoebergi. We found, however, that claw regeneration did not affect signal quality. Both males and females were unable to visually distinguish a regenerated claw from an original claw. Although regenerated males were inferior fighters, males were able to compensate for this fighting disadvantage by avoiding fights with other males. Regenerated males were, however, less likely to acquire and defend high-quality territories and consequently suffered a decrease in mating success

    Study of Molecular Sensitization Processes of Nanostructured Metal Oxides

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    Functional hybrids are nano-composite materials lying at the interface of organic and inorganic realms, combining properties and advantages of both materials, and possibly minimizing their disadvantages. Nanostructured titanium dioxide is one of the most investigated material for hybrid systems, as its application areas range from photovoltaics and photocatalysis to photo-/electrochromics, optoelectronics and sensors. Among organic molecules, metal-phthalocyanines (MPcs) are of particular interest due their great versatility and high thermal and chemical stability. A critical and very challenging issue in hybrid system engineering is the contemporary achievement of the metal oxide nano-crystals and the molecular sensitization process. As the high crystalline quality of TiO2 is commonly obtained through thermal treatments, its organic decoration is usually carried out in successive separate steps. Supersonic beams techniques (SuMBD) offer to overcome this challenge, thanks to the possibility of working with both organic molecules and inorganic aggregates, and to the ability to achieve physical and chemical processes at surfaces. The final aim of this thesis work is the study of the molecular sensitization processes, induced by supersonic beams approaches, occurring at the titanium dioxide/copper phthalocyanine interface. A preliminary extensive analysis of the nanostructured TiO2 thin films grown by PMCS is performed, in order to test the material peculiarities resulting from the non conventionality of the deposition technique. At the Parma IMEM-CNR Laboratories, the as-grown TiO2 thin films were investigated by means of several electron microscopy techniques. The morphological and luminescence properties have been evaluated by Scanning Electron Microscopy and Cathodoluminescence, while Transmission Electron Microscopy analyses provided the structural information. These studies have been integrated by surface photoelectron spectroscopies (XPS and UPS), that the candidate performed at the Trento IMEM-CNR Laboratories in order to study the material electronic properties. Moreover, the effects of annealing treatments on the observed properties have been investigated and discussed. Photoelectron emission experiments on both copper and free-base phthalocyanine, grown by SuMBD. These experiments have been carried out at synchrotron ELETTRA (Trieste). The aim of this study was to understand the real influence of the metal core on the molecule electronic properties. Taking advantages of the high resolution of the synchrotron facility, it was possible to determine well suitable fit models for both molecules. In particular, the deconvolution model related to the CuPc was decisive in the last part of this thesis work, to analyze the reactivity processes at the inorganic/organic interface. After achieving a comprehensive knowledge of the electronic properties of both the organic and the inorganic counterparts, we focused our attention to the chemical reactivity phenomena occurring at their interface, which is the final aim of this thesis work. In the Trento IMEM-CNR Laboratories, we got two hybrid systems with the same configuration (CuPc/TiO2) in a combined PMCS/SuMBD approach. In both cases the nanocrystalline metal oxide has been synthesized by PMCS, at room temperature without the need of any thermal treatment. In order to understand the role of the kinetic energy during the sensitization process, the CuPc deposition has been performed by molecular seeded beams at high (experiment A) and low (experiment B) kinetic energies. For both hybrid systems, a complete characterization of core levels and valence band states have been performed at increasing organic coverages, in order to better emphasize the dynamic of the chemical bonds formation at the interface, induced by different kinetic energies.Combinando materiali organici ed inorganici è possibile ottenere materiali funzionali ibridi con proprietà fisico-chimiche modulate al tipo di applicazione desiderata. Un sistema ibrido particolarmente promettente per l’energetica e la sensoristica è quello costituito da biossido di titanio nanostrutturato e metalloftalocianine. Una delle sfide più attuali nell’ingegnerizzazione di sistemi ibridi è la realizzazione contemporanea dell’ossido metallico nanostrutturato e della sensitizzazione molecolare. Infatti i comuni metodi di crescita del TiO2 si servono di processi termici al fine di attivarne la cristallizzazione; affinchè ciò non vada a danneggiare le molecole organiche funzionalizzanti, i processi di sensitizzazione molecolare vengono solitamente effettuati in una fase successiva. Le tecniche di deposizione basate su fasci supersonici possono superare questo ostacolo, grazie alla possibilità di lavorare con materiali sia organici (SuMBD) che inorganici (PMCS), e alla capacità di attivare processi chimici e fisici alle interfacce. Lo scopo di questo lavoro di tesi è appunto lo studio dei processi di sensitizzazione molecolare indotti da fasci supersonici, realizzato sull’interfaccia biossido di titanio/rameftalocianina (n-TiO2/CuPc). Studi preliminari sono stati effettuati separatamente sia sul materiale inorganico che sulle molecole organiche, al fine di analizzarne le peculiarità risultanti dalla non convenzionalità della tecnica di crescita. I film sottili di TiO2 as-grown sono stati analizzati presso I laboratori del IMEM-CNR di Parma, mediante diverse tecniche di microscopia elettronica. Le proprietà morfologiche e di luminescenza sono stati osservate mediante Microscopio Elettronico a Scansione e Catodoluminescenza, mentre le informazioni strutturali sono state ottenute da misure di Microscopia Elettronica in Trasmissione. Tali studi sono stati integrati da Spettroscopie di superficie (XPS and UPS) effettuate presso I laboratori IMEM-CNR di Trento, al fine di analizzare le proprietà elettroniche del materiale. Inoltre, sono stati analizzati gli effetti dei trattamenti termici sulle proprietà appena descritte. Ulteriori esperimenti di Spettroscopie da fotoelettroni sono state effettuati su film di ftalocianina-rame (CuPc) e free-base (H2Pc), al fine di individuare l’influenza del centro metallico sulle proprietà elettroniche della molecola. Tali analisi sono state effettuate presso il sincrotrone ELETTRA (Trieste). Dopo aver studiato le proprietà elettroniche di entrambi I materiali, sono stati analizzati i fenomeni di reattività alle loro interfacce. Presso i laboratori IMEM-CNR di Trento abbiamo ottenuto due sistemi ibridi con la stessa configurazione CuPc/TiO2. In entrambi i casi l’ossido metallico nanostrutturato è stato sintetizzato a temperatura ambiente con la sorgente PMCS, senza ulteriori post-processing termici. Al fine di studiare il ruolo dell’energia cinetica durante il processo di sensitizzazione, la deposizione della CuPc è stata effettuata mediante fasci molecolari supersonici sia ad alta (esperimento A) che a bassa (esperimento B) energia cinetica. Entrambi I sistemi ibridi sono stati analizzati acquisendo i core levels e gli stati della banda di valenza durante le varie fasi della deposizione. In questo modo è stato possible osservare la dinamica della formazione di legami chimici indotti dalla diversa energia cinetic

    \u201cArchivi intermediali: il valzer nella testualit\ue0 byroniana\u201d

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    Tratto ricorrente del discorso letterario fin dall\u2019antichit\ue0, l\u2019interazione fra testo e danza fa della letteratura una delle possibili chiavi d\u2019accesso alla ricostruzione storica dei fenomeni legati alla danza, ovvero un particolare archivio del corpo. Caso specifico di \uabletteralizzazione della danza\ubb \ue8 l\u2019incontro intermediale fra la testualit\ue0 byroniana e il valzer. Introdotto ufficialmente a Londra nel 1812, il valzer venne salutato come un ballo sconveniente, che riscosse comunque il favore della migliore societ\ue0, incluso quello del Principe Reggente. Nel 1813 Byron si un\uec al coro censorio con il poemetto \u201cWaltz\u201d, pubblicato in forma anonima, che sviluppava il tema della promiscuit\ue0 del nuovo ballo. L\u2019apparente moralismo di Byron viene qui letto nel contesto della Reggenza come reazione a una pratica sociale con specifiche connotazioni di genere e classe, rintracciando la presenza ricorrente del valzer a livello figurale nella produzione byroniana

    Global biosphere-climate interaction : a causal appraisal of observations and models over multiple temporal scales

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    Improving the skill of Earth system models (ESMs) in representing climate-vegetation interactions is crucial to enhance our predictions of future climate and ecosystem functioning. Therefore, ESMs need to correctly simulate the impact of climate on vegetation, but likewise feedbacks of vegetation on climate must be adequately represented. However, model predictions at large spatial scales remain subjected to large uncertainties, mostly due to the lack of observational patterns to benchmark them. Here, the bidirectional nature of climate-vegetation interactions is explored across multiple temporal scales by adopting a spectral Granger causality framework that allows identification of potentially co-dependent variables. Results based on global and multi-decadal records of remotely sensed leaf area index (LAI) and observed atmospheric data show that the climate control on vegetation variability increases with longer temporal scales, being higher at inter-annual than multi-month scales. Globally, precipitation is the most dominant driver of vegetation at monthly scales, particularly in (semi-)arid regions. The seasonal LAI variability in energy-driven latitudes is mainly controlled by radiation, while air temperature controls vegetation growth and decay in high northern latitudes at inter-annual scales. These observational results are used as a benchmark to evaluate four ESM simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Findings indicate a tendency of ESMs to over-represent the climate control on LAI dynamics and a particular overestimation of the dominance of precipitation in arid and semi-arid regions at inter-annual scales. Analogously, CMIP5 models overestimate the control of air temperature on seasonal vege-tation variability, especially in forested regions. Overall, climate impacts on LAI are found to be stronger than the feedbacks of LAI on climate in both observations and models; in other words, local climate variability leaves a larger imprint on temporal LAI dynamics than vice versa. Note however that while vegetation reacts directly to its local climate conditions, the spatially collocated character of the analysis does not allow for the identification of remote feedbacks, which might result in an underestimation of the biophysical effects of vegetation on climate. Nonetheless, the widespread effect of LAI variability on radiation, as observed over the northern latitudes due to albedo changes, is overestimated by the CMIP5 models. Overall, our experiments emphasise the potential of benchmarking the representation of particular interactions in online ESMs using causal statistics in combination with observational data, as opposed to the more conventional evaluation of the magnitude and dynamics of individual variables

    Benchmarking and parameter sensitivity of physiological and vegetation dynamics using the Functionally Assembled Terrestrial Ecosystem Simulator (FATES) at Barro Colorado Island, Panama

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    Plant functional traits determine vegetation responses to environmental variation, but variation in trait values is large, even within a single site. Likewise, uncertainty in how these traits map to Earth system feedbacks is large. We use a vegetation demographic model (VDM), the Functionally Assembled Terrestrial Ecosystem Simulator (FATES), to explore parameter sensitivity of model predictions, and comparison to observations, at a tropical forest site: Barro Colorado Island in Panama. We define a single 12-dimensional distribution of plant trait variation, derived primarily from observations in Panama, and define plant functional types (PFTs) as random draws from this distribution. We compare several model ensembles, where individual ensemble members vary only in the plant traits that define PFTs, and separate ensembles differ from each other based on either model structural assumptions or non-trait, ecosystem-level parameters, which include (a) the number of competing PFTs present in any simulation and (b) parameters that govern disturbance and height-based light competition. While single-PFT simulations are roughly consistent with observations of productivity at Barro Colorado Island, increasing the number of competing PFTs strongly shifts model predictions towards higher productivity and biomass forests. Different ecosystem variables show greater sensitivity than others to the number of competing PFTs, with the predictions that are most dominated by large trees, such as biomass, being the most sensitive. Changing disturbance and height-sorting parameters, i.e., the rules of competitive trait filtering, shifts regimes of dominance or coexistence between early- and late-successional PFTs in the model. Increases to the extent or severity of disturbance, or to the degree of determinism in height-based light competition, all act to shift the community towards early-successional PFTs. In turn, these shifts in competitive outcomes alter predictions of ecosystem states and fluxes, with more early-successional-dominated forests having lower biomass. It is thus crucial to differentiate between plant traits, which are under competitive pressure in VDMs, from those model parameters that are not and to better understand the relationships between these two types of model parameters to quantify sources of uncertainty in VDMs

    Functional Traits of Tropical Trees and Lianas Explain Spatial Structure across Multiple Scales

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    Dispersal and density dependence are major determinants of spatial structure, population dynamics and coexistence for tropical forest plants. However, because these two processes can jointly influence spatial structure at similar scales, analysing spatial patterns to separate and quantify them is often difficult. Species functional traits can be useful indicators of dispersal and density dependence. However, few methods exist for linking functional traits to quantitative estimates of these processes that can be compared across multiple species. We analysed static spatial patterns of woody plant populations in the 50 ha Forest Dynamics Plot on Barro Colorado Island, Panama with methods that distinguished scale‐specific differences in species aggregation. We then tested how these differences related to seven functional traits: growth form, dispersal syndrome, tree canopy layer, adult stature, seed mass, wood density and shade tolerance. Next, we fit analytically tractable spatial moment models to the observed spatial structure of species characterized by similar trait values, which allowed us to estimate relationships of functional traits with the spatial scale of dispersal, and the spatial scale and intensity of negative density dependence. Our results confirm that lianas are more aggregated than trees, and exhibit increased aggregation within canopy gaps. For trees, increased seed mass, wood density and shade tolerance were associated with less intense negative density dependence, while higher canopy layers and increased stature were associated with decreased aggregation and better dispersal. Spatial structure for trees was also strongly determined by dispersal syndrome. Averaged across all spatial scales, zoochory was more effective than wind dispersal, which was more effective than explosive dispersal. However, at intermediate scales, zoochory was associated with more aggregation than wind dispersal, potentially because of differences in short‐distance dispersal and the intensity of negative density dependence. Synthesis. We develop new tools for identifying significant associations between functional traits and spatial structure, and for linking these associations to quantitative estimates of dispersal scale and the strength and scale of density dependence. Our results help clarify how these processes influence woody plant species on Barro Colorado, and demonstrate how these tools can be applied to other sites and systems

    New perspectives in diagnosis and risk stratification of non-ischaemic dilated cardiomyopathy

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    Dilated cardiomyopathy is a primitive heart muscle condition, characterized by structural and functional abnormalities, in the absence of a specific cause sufficient to determine the disease. It is, though, an 'umbrella' term that describes the final common pathway of different pathogenic processes and gene-environment interactions. Performing an accurate diagnostic workup and appropriate characterization of the patient has a direct impact on the patient's outcome. The physician should adapt a multiparametric approach, including a careful anamnesis and physical examination and integrating imaging data and genetic testing. Aetiological characterization should be pursued, and appropriate arrhythmic risk stratification should be performed. Evaluations should be repeated thoroughly at follow-up, as the disease is dynamical over time and individual risk might evolve. The goal is an all-around characterization of the patient, a personalized medicine approach, in order to establish a diagnosis and therapy tailored for the individual patient
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