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The structural role of light elements in magmas: P, Cl and S
No full textThis study is focused on the geochemical and structural behaviour of light elements in magmas. In particular we are interested in investigating the role of phosphorus, chlorine\ud
and sulfur in silicate glasses in order to get important information to apply in a natural model. The geochemical and structural role of P, S and Cl in silicate glasses of\ud
composition relevant for the Earth Sciences has been investigated by X-ray Absorption Spectroscopy (XAS). The geochemical behavior of these elements in silicate melts and\ud
glasses is of major importance for problems ranging from volcano-climate interactions to the genesis of ore deposits of great economic importance to industrial glass-forming\ud
processes and treatment of vitreous waste material from refuse incineration activities.\ud
Evaluation of such problems requires new data on the structural environments around P, Cl and S dissolved in silicate melts and potential interactions with metal cations. Direct structural data (local bonding environment) are lacking, due to experimental difficulty in analyzing minor to trace light elements. We collected high quality XANES and EXAFS data on synthetic glasses in order to obtain information on the local chemical and structural environment around the studied elements. Use of synthetic glasses produced under controlled pressure, temperature and oxygen fugacity conditions allowed to understand how the structural and geochemical role of these light elements vary\ud
according to the physical and chemical conditions existing in the magma chamber. Data analysis has been accomplished by comparison with well characterized model compounds with known absorber oxidation state and coordination number. Theoretical XANES calculations have further helped in understanding the chemical and structural environment of the studied elements (e.g. cations bonded to [PO4]3- groups or to Cl- and S2- anions) in the synthetic glasses\u
Il contributo delle ittiofaune alla definizione paleoambientale e stratigrafica della fase post-evaporitica del Messiniano.\ud \ud The contribution of the ichthyofauna in the paleoenvironment and stratigraphic definition of the Messinian post-evaporitic phase.\ud
No full textThanks to the hypothesized spectacular catastrophic scenario, the Messinian salinity crisis has represented one of the most discussed topic in Earth Sciences in the past 30 years. The possibility that during the Messinian the Mediterranean was at times completely desiccated has received considerable attention in the scientific community and stimulated an unusual quantity of multidisciplinary researches, which generated cogent and often conflicting\ud
debates. The amazing development of stratigraphic techniques in the last decade has greatly increased our knowledge of the events related to the Messinian salinity crisis. The refinement of the Neogene bio- and magnetostratigraphy in the Mediterranean region and the consequent improvement of a detailed astronomically-tuned time scale have provided a useful tool for high resolution correlations and paleogeographic reconstructions (Hilgen et al., 1999).\ud
Moreover, the accurate correlations available have favoured the interpretation of a reliable sequence of environmental changes and their relationships with global and regional climatic and tectonic events (Krijgsman et al., 1999; Hodell et al., 2001; Rouchy & Caruso, 2006).\ud
Based on these studies the base of the Messinian (Tortonian-Messinian boundary) has been fixed at 7.25 Ma and its end (Messinian-Zanclean boundary) dated at 5.33 Ma (Hilgen et\ud
al., 2000). The top of this stage corresponds to the so-called ‘Terminal Messinian Flooding’, a catastrophic return to fully marine condition synchronous in the whole Mediterranean. The well developed and widely distributed cyclic arrangement of the Messinian deposits suggested\ud
the classical three phase subdivision (see Krijgsman et al., 1999): 1) Pre-evaporitic phase, characterized by cyclic diatomite-sapropel sedimentation that affected the basin in response to the precessional forcing of ocean stratification (7.25-5.96 Ma); 2) Evaporitic phase (=Lower\ud
Evaporites; 5.96-5.59 Ma); 3) Post-evaporitic phase (5.52-5.33 Ma). The second and the third phases correspond to the Salinity Crisis event. The stratigraphic resolution within the three phases is very different, mainly because of the lack of biostratigraphic control in the evaporitic and post-evaporitic phases, classically included in the so-called ‘Non Distinctive Zone’. The lack of biostratigraphic control limits the possibility to obtain a detailed stratigraphic framework for this interval. Moreover, the scarcity of fossils and the heterogeneity of sedimentary products that characterizes the Salinity Crisis-related deposits makes difficult the understanding of the physico-chemical and palaeoenvironmental conditions of the waterbody during the span of this event and the resulting palaeogeographical setting of the Mediterranean. According to the original hypotheses of Messinian palaeoenvironmental evolution the isolated Mediterranean was affected, during the evaporitic phase (Lower Evaporites), by a cyclic evaporative draw down of the sea level that shallowed up to the complete desiccation. As a consequence of the cyclic progressive desiccation, an increased concentration of the brines culminating in the deposition of sulphate-rich evaporites widely occurred in the basin. The evaporitic phase was followed by a short time interval characterized by non-deposition and erosion (Messinian gap), and by the subsequent deposition of the non-marine sediments of the ‘Lago-mare’ event (Krijgsman et al., 1999).\ud
The progressive sea-level drop and the successive esiccation of the basin were responsible for the drastic change of the drainage pattern in the peri-Mediterranean region, resulting in the partial refill with fresh- and brackish waters of Paratethyan origin (e.g. Cita et al., 1978; McCulloch & DeDekker, 1989). The post-evaportic “Lago-Mare” phase in the Mediterranean realm was used initially to describe a brackish to freshwater environment characterized by a fauna of molluscs (“Congeria beds”, or “Melanopsis beds”) in sediments deposited ending the\ud
Messinian Salinity Crisis immediately prior to Pliocene marine re-flooding. Thus, the desiccation model implies that during the Salinity Crisis the Mediterranean waterbody was characterized by dramatic and rapid environmental changes, from hypersaline to completely dried out, to hyposaline.\ud
This study is focused on the post-evaporitic ‘Lago-mare’ phase and provides a new palaeoenvironment interpretation of the Mediterranean waterbody during such a interval of\ud
the Messinian history using fossil fish remains. Up to date, the interpation of the paleoecological setting of the Mediterranean Basin during the evaporitic and post-evaporitic ‘Lago-mare’ phase, has been based analysis of the microfaunas (foraminifera and ostracods) and macroinvertebrates (molluscs). The integrated palaeoecological analysis of the entire fossil assemblage (benthic foraminiferans, ostracods, molluscs, fishes) highlights the key role of fish remains as palaeoenvironmental indicators. Because of their mobility and frequent migratory behaviour, marine fishes can co-occur with fresh- or brackish-water organisms, and, at the same time, provide useful information for the interpretation of the palaeoenvironmental conditions of the areas surrounding those testified by the resident biota.\ud
The new paleoichthyological approach presented herein has been performed in four different geodynamic contexts, representative of four different depositional environments, in order to provide a reliable and comprehensive large-scale interpretation. The main objective of this paper is to investigate the fossil fish remains, mostly otoliths, collected from the ‘Lago-mare’ deposits of five localities in the Italian peninsula.\ud
In this Thesis I have analysed eleven stratigraphic section referred to the postevaporitc ‘Lago-mare’ phase. Five of these sections resulted productive for such a study. As\ud
documented above, all these sections are representative of a different geodynamic context: Capanne di Bronzo section (Marche basin) is typical of the foreland basin system; Cava\ud
Serredi and Podere Torricella (Tuscany basin) are typical to the back-arc basins active since Tortonian times; Le Vicenne (Abruzzi basin) (Cipollari et al., 1999a) and Ciabòt Cagna (Piedmont basin) (Gelati & Gnaccolini, 2003) are refered to the small basins located in the inner sector of the Apenninic chain.\ud
Otoliths are calcareous structures associated with the ear of fish involved in vestibular and acoustic functions (Popper & Fay, 1993). Although fishes posses three pairs of otoliths, only the largest, the Sagitta, is commonly used in paleontological studies. These calcareous structures are often characterized by a wide interspecific morphological variability, and for this reason are sometime used in species-levels taxonomic study. Fossil otoliths are very\ud
common in Cenozoic and Quaternary marine and brackish deposits, representing the most common remains of teleost fishes (Nolf, 1985). Because of their abundance and diversity, fossil otoliths usually provide a large amount of paleoecological and paleogeographical data which are necessary for paleoenvironmental reconstruction (Nolf, 1985). The otoliths usally are been presents in the fossiliferous horizons where the carbonate structure, such as molluscs, bryozoan, corals, etc., are to be well-preserved.\ud
In the fossiferous horizons here studied the specimes are extremely well-preserved and fine structures useful for taxonomic determinations are usually clearly recognizable. Because of the excellent preservation of the otoliths, we conclude that the fossil assemblages documented herein reflects autochthonous embedding, thereby excluding the possibilities of reworking from older rocks and contamination from younger deposits. This is also suggested\ud
by the preservation of delicate mollusc shells and by the mutual occurrence of ostracod valves at different growth stages.\ud
The systematic and palaeoecological analysis have revealed a well diversified fish assemblage, composed by 5517 specimens, among which 44 taxa have been recognized. From\ud
an ecological point of view, the total assemblage consists of four different ecological guilds: anadromous, estuarine residents, marine migrants and marine stragglers. The palaeoecological analysis reveals a coastal shallow marine environment strongly influenced by unsteady continental outflow in the deposizional environment recorded in the section here analysed.\ud
Based on the the palaecological and palaeoenvironmental data, all depositional areas here considered are closely associated to a basin characterized by normal marine waters. These findings clearly demonstrate that fishes, because of their mobility and migratory behaviour,\ud
represent a useful tool for the large-scale interpretation of the environmental conditions of the Messinian Mediterranean waterbody.\ud
The repetitive occurrence, in the stratigraphic sections analysed herein, of well diversified assemblages of marine stenohaline and euryhaline fishes necessarily implies that a\ud
basin characterized by marine water was present close to the depositional environments. The highly diverse taxonomical composition and the ecological disparity that characterize the fish assemblages of these localities suggest that the Mediterranean Basin has already had a\ud
complex and fully developed ecological structure during the late Messinian. Moreover, the statistic analysis carried out on the fish assemblages testify the presence of a marine\ud
environment linked to the depositional setting recorded in the stratigraphic section here analysed. This palaeonvironment model is in contrast with the classical model (Hsü et al., 1973, 1977) that suggested the widespread development of brackish/oligohaline conditions in\ud
the Mediterramean Basin during the post-evaporitic phase.\ud
In order to better define the paleontological significance of these upper Messinian fish assemblages, the oxygen, carbon and strontium isotopic composition of fish otoliths and other fossils (ostracods and molluscs) has been measured. This measurements is in agree with the palaeoenvironmental analysis that indicate the presence of marginal brakish environment linked to the normal marine condition in the Mediterranean Basin.\ud
The benthic macro- and microfauna characteristic of the fossiliferous horizon is clearly indicative of a brackish environment during the post-evaporitic phase. Actually, the\ud
presence of the marine taxa in the fish assemblage that characterized the brackish environment testified the permanently connection with a basin characterized by normal\ud
marine water body. The common occurrence of estuarine resident and the presence of marine fishes is evidently consistent with the hypothesis of a transitional environment characterized by thalassogenic waters, thereby confirming that the ichthyofaunal assemblages can be\ud
considered as a useful complementary tool in defining the levels of marine influence on brackish biotopes (see Mariani, 2001).\ud
The interpretation of the composition of the waterbody during the deposition of the post-evaporitic phase has been largely debated and several studies of isotope geochemistry,\ud
clay mineralogy, and palaeontology (foraminiferans, ostracods, molluscs) have been produced, resulting in a rather confused scenario of fresh-, brackish-, oligohaline or mesohaline waters. The paleontological and geochemical analysis of fossil fish remains clearly indicates that a new palaeoenvironmental interpretation of the Messinian ‘Lago-mare’ event is necessary, and provides an unquestionable demonstration that the re-establishment of\ud
normal marine conditions in the Mediterranean preceded the Mio-Pliocene boundary. The possibility of an intra-Messinian marine reflooding has been proposed by several authors (e.g. Butler et al., 1995; Riding et al., 1999; Pedley & Maniscalco, 1999; Steffahn & Michalzik, 2000; Griffin, 2002; Aguirre & Sánchez-Almazo, 2004), and evidences of at least periodical marine influxes are rather common in the ‘Lago-mare’ sedimentary record (e.g. Iaccarino & Bossio, 1999; Iaccarino et al., 1999; Rouchy et al., 2001; Crescenti et al., 2002; Clauzon et al., 2005). However, the hypothesis of pre-Pliocene reflooding has never been commonly accepted, as the proposed evidence has been considered weak or inadequate (e.g. Fortuin &\ud
Krijgsman, 2003). Fossil fish remains indicate that the rapid and catastrophic Pliocene inundation from the Atlantic was preceded by a progressive transgression that re-established the marine biotic communities. These findings are in agreement with the scenario postulated\ud
by Keogh & Butler (1999) who suggested that during the ‘Lago-mare’ phase the base-level of the Mediterranean was within the range of the world’s oceans even though the waterbody probably had a different but internally homogeneous isotopic composition.\u
Regole, criteri di esproprio e di riuso per i complessi conventuali soppressi nelle Marche dal 1860 al secondo ‘900
No full textL’indagine affrontata nella ricerca che seguira', si prefigge […] l’obiettivo di approfondire un aspetto che, nella realta' marchigiana, e' risultato decisivo sia sul piano storico sia sul piano del potere di lasciare traccia sulle realta' urbane o capoluogo, o piu' semplicemente, di manipolarle. […].\ud
Le soppressioni degli ordini conventuali portate avanti su scala nazionale che precedettero l’acquisizione di un rilevante numero di beni immobili, sia architettonici che fondiari, da destinare a varie esigenze, innanzitutto di tipo funzionale per nuove destinazioni comunitarie, ma anche per un nuovo inserimento di essi in un circuito economico di tipo speculativo, vennero certamente guidati da motivazioni innanzitutto politiche.\ud
Questo aspetto storico, che assunse proporzioni consistenti in innumerevoli centri italiani, fu particolarmente accentuato nelle Marche, dove i suoi stretti legami tradizionali con l’autorita' pontificia si sintetizzo' in una organizzazione ecclesiastica conventuale particolarmente significativa, distribuita puntualmente su tutto il territorio. Tra l’altro, in un ambito regionale dove si trovo' ad agire con risolutezza il Commissario generale straordinario Lorenzo Valerio, si anticiparono gli effetti delle leggi nazionali di soppressione del 1866 e dell’anno successivo, procedendo ad acquisizioni generalizzate, dietro l’emanazione di decreti. Gli stessi si occuparono di far fronte ad una consistente mole di richieste inoltrate da enti comunali ed organi pubblici settoriali, situazione facilmente ricostruibile dalle fonti documentarie. Questi necessitavano di una strutturazione spaziale e distributiva pressoché totale, in particolare nei centri di maggiore attrazione antropica, quali Urbino, Ancona, Fermo ed Ascoli Piceno ad esempio.\ud
In questo contesto storico ed amministrativo fortemente sollecitato, molti sono gli aspetti meritevoli di approfondimento, specialmente per gli effetti di esso sulla citta' in genere, e sulle realta' urbane che maggiormente caratterizzano il territorio marchigiano, sempre tenendo un occhio di riguardo a dibattiti e vicende nazionali.\ud
La soppressione delle comunita' religiose, infatti, e la confisca dei loro beni, in particolare insediamenti dall’elevato pregio storico-architettonico, determinarono evoluzioni di molteplici aspetti che definiscono porzioni di citta', o piu' semplicemente un preciso contesto, caratterizzato da fatti architettonici, e non solo.\ud
Un ruolo preminente lo ebbe la funzione, certo, che riguardera' una elevata quantita' di spazi da reimpiegarsi per usi collettivi, di natura completamente diversa. Limitare la ricerca esclusivamente alle nuove destinazioni funzionali, pero', risulterebbe alquanto riduttivo; essa infatti escluderebbe dalla riflessione una serie di condizioni altrettanto importanti, assolutamente necessari per captare nuove chiavi di lettura, al fine di comprendere esattamente il grado di cambiamento che riguardera' singoli fatti urbani, quali gli insediamenti conventuali che, in molti casi, proprio per la loro mole compositiva e dimensionale, potevano essere considerati come vere e proprie parti di citta', soprattutto se rapportati alla scala dei centri marchigiani.\ud
Alterazioni compositive, parziali demolizioni, ricostruzione di nuovi nuclei edilizi, ridisegno o piu' semplicemente perdita di sistemi di elementi che portarono alla cancellazione definitiva dell’equilibrio tra il complesso conventuale ed il suo intorno; sono semplicemente le considerazioni che vanno avanzate al fine di stabilire i cambiamenti che coinvolsero numerose realta' urbane, caratterizzate con tratti distintivi.\ud
La ricerca e l’approfondimento di queste dinamiche urbane sono cruciali per capire le condizioni odierne ed i problemi rimasti aperti, in quanto le citta' in genere vanno sempre intese nella loro evoluzione spazio-temporale.\ud
L’adattamento di spazi a nuove funzioni, con la frammentazioni di complessi sistemi stratificatisi nei secoli come pertinenze e giardini, hanno lasciato aperte questioni che, nel momento attuale, andranno certamente affrontate.\ud
Tali decisioni decretarono, soprattutto in ambiti provinciali, la rinuncia del progetto, a causa anche della cronica mancanza di disponibilità finanziarie, inteso secondo gli strumenti piu' tradizionali, quali in concorso di progettazione, o piu' semplicemente previo incarico diretto. In altre realta' di maggiore consistenza, quale ad esempio Roma capitale, si assistette alla redazione di importanti progetti che riguardavano soprattutto sedi ministeriali, tuttora parti considerate primarie nell’immagine complessiva della citta'.\ud
Il confronto con insediamenti conventuali dismessi, per capire le modalita' per una loro nuova utilizzazione nel senso contemporaneo, trova la sua materializzazione ad Urbino, probabilmente unico caso di progettualita' nelle Marche, almeno fino ai tempi piu' recenti, quando diverse limitate operazioni hanno riguardato alcuni edifici ex monastici, di buona qualita' progettuale e redatti secondo una consapevolezza storica. Oltre tutto, uno sguardo attento va sempre mantenuto verso importanti esperienze progettuali compiute in alcuni paesi europei, come ad esempio in Portogallo, dove architetti di primo livello come Eduardo Souto De Moura e Joao Luis Carrilho Da Graca si sono confrontati con il recupero di consistenti sedi monastiche.\ud
In un contesto conoscitivo in cui il sapere di tali evoluzioni storiche, e le rispettive condizioni ed effetti sull’architettura dell’intera citta', una ricerca che riguarda la soppressione degli ordini religiosi di ogni appartenenza, e l’acquisizione dei rispettivi beni immobili e mobili di proprieta', vuole infine porre nuovi riferimenti in un settore scientifico che dispone di rilevanti fonti storiche, ma che solo parzialmente ha ricostruito pienamente una fase importante della realta' italiana e marchigiana, sia sul piano storico, dove rimane da affrontare una serie di problemi aperti, sia sul piano urbano e prettamente architettonico.\ud
Le attuali condizioni di una serie di conventi o parti di conventi gravemente alterati nel corso dei decenni, ci porta inevitabilmente a porci una serie di interrogativi ai quali le istituzioni, unitamente a tutti i soggetti che a vario titolo hanno potere e capacita' di incidere sulla citta', dovranno necessariamente proporre risposte.\ud
L’acquisizione, ad esempio, dell’antico convento dei Cappuccini sul Colle di Ancona dal Politecnico delle Marche, quindi quella dell’antico convento dei filippini dall’ateneo urbinate, dovranno farci comprendere se la felice esperienza Bo-De Carlo, sia ripetibile. Ambiti urbani non risolti, quindi, che doverosamente attenderanno delle risposte nell’immediato futuro, quando si affronteranno nuovi itinerari progettuali che porteranno a ripensare complessivamente secondo nuove logiche, luoghi e contesti fortemente caratterizzati, capaci di apporre nuovi segni distintivi di qualita' sulla citta' contemporanea.\ud
\u
Optimal state transfer in long-range interacting spin-chains\ud
Get PDFIn recent years, the interest in quantum communication channels has experienced a rapid increase, also in view of their use as a bus between registers and processor within a quantum computer. Despite the fact that the majority of protocols for quantum communication rely on photons,\ud
because of their weak interaction with the environment, and of the welldeveloped optical fiber technology, it is not always possible to use photons when one needs a frequent exchange of information between distant qubits.\ud
For example, in the case we have mentioned, the communication between different parts of a quantum computer would require a continous conversion of stationary qubits (i.e. the information stored in the components of the\ud
quantum computer) into ying qubits (i.e. photons), in order to transmit information. This procedure leads to several interfacing problems between the two different kinds of physical systems, that could be avoided by using,\ud
as a quantum channel, the same kind of physical system that is used for realizing the quantum computer. Indeed, a seminal paper by Bose, suggested to use spin-chains as a quantum channel for short or mid-range communication, showing that, by means of the magnetic interaction between\ud
the spins composing the chain, the information is transferred by only letting the system evolve dynamically, without the requirement of any external control. Transferring quantum information between distant qubits through spin-chains would be highly desirable, as, in general, this is a procedure which requires the repeated application of swapping gates and is, consequently,\ud
higly experimentally demanding. After the first proposal, there has been a spread of works investigating the dynamical behaviour of spinchains and possible optimization techniques for enhancing its performances as a quantum channel.\ud
There has been proposed a large amount of schemes for reaching perfect state transfer by optimising the system over a variety of parameters, as, for example, the robustness against errors and a restricted ability to engineer the state, or, on the opposite, the ability of engineering the couplings and a definite interval of time for the state transfer, or by allowing other kinds of control over the chain. However, all the schemes proposed, not only present some kind of side-effects, as, for example,\ud
a potentially indefinite waiting time for observing the transfer, or a difficult generalization to the transfer of multiple-qubit states, or are not scalable with the size of the system, or require a demanding technology in order\ud
to be implemented, but also rely on the nearest-neighbour modellization of the chain. The nearest-neighbour model appears to be a rather theoretical model, with respect to a long-range interacting model, such as a spin-chain\ud
which exhibits dipolar couplings. In fact, the experimental implementations of spin-chain based on trapped particles, such as ions or electrons, exhibit dipolar couplings. Indeed, trapped particles, like ions or electrons,\ud
are suitable for implementing both a scalable quantum processor, and a quantum channel, so they represent one the most interesting playgrounds for the implementation of spin-chain.\ud
In literature, there have been only few examples of works taking into account long-range interactions, which, in general, have always been regarded as a sort of perturbation with respect to the nearest-neighbour\ud
(NN) model. However there are relevant features of the long-range interactions that cannot be captured within the frame of only NN-coupling. An example is provided by the completely different behaviour in presence of defects\ud
such as vacancies along the chain. The presence of empty sites, in fact, in the NN case would prevent the use of the system as a quantum channel, whereas the long-range interacting chain is more robust against this kind of\ud
errors, which, for example, could be the consequence of an imperfect chain-filling.\ud
We start our investigation with the aim of reaching a deeper understanding of the dynamics of long-range interacting systems, and of proposing an optimization scheme, for this class of chains, which could avoid, as much\ud
as possible, the drawbacks of the previous proposals. Our goal is to find a general and easy-to-implement prescription that allows to significanlty enhance\ud
the performances of the channel. In order to accomplish this task we adopt an approach which lead us to start our investigation from the very beginning. In fact, we look for the most general considerations about system\ud
properties, like symmetry, energy spectrum and eigenvectors, that allows a generic physical system to transfer perfectly information, in order to understand\ud
their role in the communiation process.\ud
We find that, given a fixed transmission distance, perfect state transfer, moreover in the shortest possible time, can be achieved only by a system made of two spins. This ideal system, however, results unpractical, due to the decrease of the interactions with the inter-spin distance , which makes it impossible to transfer a state over an arbitrarily long distance. In fact, in presence of whatever kind of noise, the coupling between sender and receiver would result too weak after a short distance. The obvious way to circumvent this problem relies on filling the space in between with other spins, as in the ordinary spin-chains. However, this procedure on one side enforces the communication, but on the other, lowers the fidelity and increases the transfer time. What is, then, the smartest way to fill in the space between sender and receiver in order to keep the fidelity of transmission close to unity and the transfer time reasonably short?\ud
We find an answer to this question which leads to optimal results and, most notably, largely independent of the number of spins in the chain, hence scal-able. Therefore, our scheme can be applied also to mid-range communication\ud
in a rather straightforward way. The key element is a joudicious balance between the ideal two-spin chain and the complete chain with equally spaced spins. We do not resort to specific design or challenging system engineering,\ud
but simply identify a general and easy prescription to optimize the performances of the spin chain as a quantum channel. Furthermore, our scheme leads to optimal state transfer also in all the higher excitation subspaces,\ud
allowing the transmission of multiple-qubit states and of multiple-entangled states. We show explictly how this applies in the case of two excitations travelling along the chain. The Hamiltonian of the system, indeed, acts on the different excitations as a whole entity, and, in this terms, allows a mapping in which the degrees of freedom relative to the positions of the excitations are mapped into a single index spanning all the states in the\ud
configuration space of the system. We study the double excitation case also in connection with the eventuality of thermal noise in the system. This investigation is quite general and could be used also as a scheme appliabe to\ud
other situations, such as memory effects in the channel.\ud
Our work is organised as follow: in Chap.1 we introduce the basic concepts concerning the quantum channels and introduce the basic protocol of communication through a spin chain that has been originally proposed in Ref. [2]. We also provide an overview of the optimization schemes proposed in literature, and of both their advantages and their disadvantages. In Chap. 2 we illustrate the three main proposals for experimentally implementing the spin-chain dynamics, and show how it naturally arises, in\ud
the two most interesting cases, the dipolar-coupling Hamiltonian. After a very short overview of the state of the art concerning long-range interactions, and of the standard way to approach these systems, in Chap.3, we\ud
start our original investigation, by examining the most general conditions under which the transfer fidelity is maximized. We analize the role of spatial symmetry in connection with the properties of the eigenvectors and of the relative eigenenergies. These considerations lead us to consider symmetry a necessary condition for perfect state transfer, and to derive also a sufficient condition. We also prove that the ring of qubits is not a suitable configuration for transferring a state between two parties, by showing how it does not match the conditions we have found for perfect state transfer. Furthermore, by means of the symmetry, we provide an explanation for the dependence,\ud
of the ring performances, on the parity of the number of spins, despite its ferromagnetic nature. In Chap. 4 we further explore the implications of our results by including defects, e.g. empty sites, in the chain. In particular we first examine a single-hole chain and then skip to the double-hole case.\ud
The latter ones lies at the heart of our procedure for achieving, by practical means, perfect state transfer. We show that, within our scheme, not only the performances of the system are dramatically enhanced, but also, given\ud
a fixed transmission distance, are invariant under system rescaling. We also extend our procedure to the double-excitation subspace. Finally, we examine the case in which a second excitation is induced in the chain by thermal\ud
noise.\ud
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NAD+ Metabolism: aspects of biosynthesis and degradation\ud
No full textIncreasing evidences have indicated that NAD+ and NADH play critical roles not only in energy metabolism, but also in several cellular functions including calcium homeostasis, gene expression, ageing, immunological mechanisms and cell death. The research work focused on two important aspects of NAD+ metabolism, the biosynthesis with a detailed analysis of NAD+ biosynthetic pathways in human keratinocytes and, on the other hand, the NAD+ degradation by the purification and characterization of NAD(P)+ -glycohydrolase from porcine liver.\ud
The first study is originated from the NAD+ involvement in skin cancer prevention mechanisms that include enhancing DNA repair as a substrate of poly(ADP-ribose) polymerases (PARPs), preventing photoimmune suppression, serving as a cofactor for energy generation necessary for the formation of a functional cornified epidermal barrier, and for the release of agents such as leptin known to have protective effects in skin. We report here an analysis of NAD+ biosynthetic pathways present in human keratinocytes (HaCat) cells. All our experiments were carried out with\ud
HaCat cells initially grown in NAD+ precursor free media in order to evaluate the functionality of the different biosynthetic pathways using the same starting conditions. In addition to the wellknown nicotinamide (Dieterich) and nicotinic acid (Preiss-Handler) pathways, we investigated the potential of nicotinamide riboside (NmR) to serve as a NAD precursor. Our results confirm the presence of the Preiss-Handler and Dieterich salvage pathways, but showed that HaCat cells also are able to efficiently synthesize NAD+ starting from NmR via two different pathways involving\ud
conversion to nicotinamide mononucleotide and via conversion to nicotinamide. The rates of conversion and maximum NAD content that can be achieved vary among the different precursors.\ud
The second part of the work focused on the purification and characterization of NAD(P)+-glycohydrolase from porcine liver. NAD+ glycohydrolases (NADase, EC 3.2.2.5) belong to the list of enzymes that cleave the nicotinamide-glycosyl bond of NAD+ to form nicotinamide (Nam) and adenosine diphosphoribose (ADPR), and they are highly involved in the Ca2+ cellular homeostasis.\ud
In addition to NAD(P)+ hydrolysis, this enzyme shows other catalytic activities, as transglycosidation, ADP-rybosil cyclase (also known as cADPR synthase) and cADPR hydrolysis\ud
reactions. NAD(P)+-glycohydrolase was partially purified from microsomal membranes of porcine liver after solubilization with Triton X-100. Porcine liver NADase showed a molecular mass of 64kDa. Kinetic studies were carried out in order to characterize the partially purified enzyme. The results obtained demonstrated an high stability of the purified enzyme in a wide range of temperature and pH. In order to clarify the catalytic mechanisms, NADase activity was assayed in presence of several ion species and of denaturating agents, and also utilizing NAD+ analogues as\ud
substrate. In addition to the NAD+ hydrolysis activity, the purified enzyme showed other catalytic activities, such as transglycosidase and ADP-rybosil cyclase, as reported in literature for many NAD+ glycohydrolase enzymes.\u
New metal complexes supported by scorpionate\ud and macrocyclic ligands: chemistry and biological\ud studies
No full textI and my research group have focused our attention on the study of the coordinative ability of monoanionic heteroscorpionate ligands based on bis(pyrazol-1-yl)methanes\ud
containing acetate or sulfonate groups as the third coordinating moiety in particular toward rhenium. The similarity between technetium and rhenium chemistry, in fact, determined a widespread use of the latter as a technetium surrogate to perform macroscopic chemistry of\ud
potential radiopharmaceuticals. In this way, a ‘‘cold’’ material (the natural isotopic mixture of 185Re and 187Re) can be advantageously manipulated instead of the radioactive nuclide 99gTc (t1/2 = 2.12 105 y, Eâ = 292 keV). On the other hand, rhenium has two â- emitters isotopes 186Re (â-max = 1.07 max = 2.10 MeV; t1/2 = 17 h) which are of great interest to nuclear medicine due to their physical and nuclear properties finalized to a potential application in the radiopharmaceutical. For this reason, a renewed interest in rhenium coordination chemistry\ud
fluourished, finalized to a potential application in the radiopharmaceutical field of rhenium itself, which was no longer considered as a mere technetium substitute for chemical investigations at macroscopic level. In the past few years the so-called ‘‘metal fragment’’ strategy for the synthesis of new technetium and rhenium radiopharmaceuticals revealed to be a promising approach. This methodology is based on the preparation of intermediate species comprising a stable building- block\ud
constituted by the metal and suitable ancillary ligands and labile modentate groups (e.g., water molecules or halide groups), which can be easily replaced by chelating bi- or tri-dentate ligands eventually conjugated to a specific biomolecule.\ud
According to this strategy, we have reported on a new class of compounds containing the stable metal fragment [Re(O)(NNO)]2+ (N,N,O = tripodal heteroscorpionate ligand). In fact, in order to stabilize the monooxo rhenium core, heteroscorpionate ligands were chosen due to their\ud
coordinative flexibility and proper (facial) stereochemical arrangement. In particular, monoanionic bis(pyrazol-1-yl)methane derivatives, containing acetate (Hbpza = bis(pyrazol-1-yl)acetate; Libdmpza = Lithium[Bis(3,5-dimethylpyrazol-1-yl)acetate]) or sulfonate groups (Libdmpzs = Lithium[Bis(3,5-dimethylpyrazol-1-yl)methanesulfonate]), by reaction with [NBu4][Re(O)Cl4],\ud
gave a series of intermediate compounds Re(O)(NNO)Cl(X), where the octahedral coordination sphere is filled with two modentate groups (X = Cl or OR) whose structure depends on the type of NNO ligand and solvent utilized. Besides, we have seen that the effectiveness of replacement of\ud
two modentate groups of intermediate species with a bidentate chelate (ethylene glycol, malonic acid and 1,3-propandiol) depends on the nature of the heteroscorpionate, and that the substitution takes place easily when N,N,O ligand bear methylated pyrazolyl rings\u
Sistemazione del sagrato della chiesa di S.Giacomo della Marca di Ascoli Piceno
No full textCHIESA OGGI \ud
Ordine degli Architetti di Ascoli Piceno\ud
PROGETTO SEGNALATO EX AEQUO - PROVINCIA DI ASCOLI PICENO\ud
Località: Ascoli Piceno\ud
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Il complesso di S. Giacomo della Marca è nel quartiere Borgo Soletà, tra il nucleo storico di Ascoli e una zona di edilizia popolare degli anni ‘60/’70.\ud
La chiesa, dall’impianto semplice, risale agli anni ‘60.\ud
Il progetto prevede un sistema di piani che diviene segno trasversale e riconnette la piazza con la via retrostante alla chiesa.\ud
Dall’alto: planimetria di progetto, descrizione degli spazi\ud
alle diverse quote, rendering.\ud
Tale segno si estende da un lato all’interno della piazza, dove si trasforma in palco per le manifestazioni all’aperto; dall’altro fino a via Rossini erodendo spazio al campetto sportivo: un giardino pensile che articolandosi copre nuovi spazi ipogei, ospita attività sportive. Il percorso distributivo incassato si protende verso via Rossini. L’alternarsi di segni verdi e pavimentati ridefinisce il prospetto su via Verdi.\ud
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MECHANICAL AND COMPRESSION CHARACTERIZATION OF PELLETES\ud PREPARED BY EXTRUSION-SPHERONIZATION\ud
No full textPart 1\ud
The first part concern the characterization of mechanical and compression properties of pellets prepared by extrusion-spheronization. Thirteen batches of pellets were prepared all in the same condition, using five materials (corn starch, α-lactose monohydrate, anhydrous dicalcium\ud
phosphate, peg 6000 and amidated pectin) plus microcrystalline cellulose as main binder, in fixed\ud
ratio, 75, 50 and 25% respect the cellulose amount. A further batch was prepared using only microcrystalline cellulose. A characterization program were carried out on the compression and mechanical properties of the starting materials, powder mixtures and pellets, the latter analysed\ud
either as single unit that during compression. Results showed as pellets compaction behaviour is strongly related to the properties of powder mixtures used for their preparation and it could be also derived from single components characteristics according with the ratio used. Diametrical compression tests and pellets images before and after such test enabled to link mixtures and pellets\ud
compaction behaviour, moreover these tests allowed to classify pellets as fragmenting and deforming. Despite the similar compaction mechanism mixtures and pellets behaved completely different in term of tablettability. A marked increase on surface area resulted crucial in order to\ud
obtain pellets tablets, as confirmed by the fragmenting batches results.\ud
All pellets classified as deforming seem suitable as core materials for the film coating application,in the preparation of multiparticulate controlled release tablets. They resist to the compaction process retaining their shape, so they represent good system in order the maintain the film integrity.\ud
All pellets classified as fragmenting pellets do not result useful as “cushioning agents” in multiparticulate controlled release tablets. Moreover the spheronization carried out on dense extrudate (as in this case) do not represent the best methodology for this purpose.\ud
Part 2\ud
The second part, carried out at the school of pharmacy and chemistry, John Moore University (UK) under the supervision of Dr. M. Roberts, concerning the influence of hydro-ethanolic media on the aspirin release profiles from hypromellose matrices. Percent aspirin released increased with increasing levels of ethanol in the dissolution media, correlating with the drug’s solubility, however,dose dumping of aspirin did not occur. An initial rapid release was observed in media comprising 40% ethanol. Release in these conditions was considered to be both erosion and diffusion-mediated, in contrast to the release in 0, 10, 20 and 30% ethanol media, where erosion-controlled release\ud
dominated. Image analysis of matrix swelling indicated a slower initial interaction between ethanol and hypromellose accounting for the initial rapid release. Cloud point studies suggested that ethanol retarded hydration of the polymer.\ud
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Reconstruction of local climatic evolution by atmospheric aerosol analysis \ud
No full textIn recent decades, the interest of the scientific world against climate change is always more important. To arouse much interest contributed enormously the numerous work appeared in the scientific literature in the years 80; in them has been tested that over the last century, the global average surface temperature has increased by about 0.6°C.\ud
It is now established that the emissions of greenhouse gases and aerosols caused by human activity continued to alter the surface temperature of the earth. In the\ud
IPCC (Intergovernmental Panel of Climate Change), of 2007, has been pointed out how these emissions have increased, and how they influenced the climate particularly in the last 20 years.\ud
However, it is still open the question about the assessment of the climate impact of aerosol (generally indicated as aerosol forcing).\ud
The total suspended particulate is a complex mixture of heterogeneous substances, both inorganic and organic. The data of concentration and composition in literature and limit values imposed by the regulations are referring to particles with an aerodynamic diameter less than 10 μm, the\ud
pollution called PM10.\ud
This particulate fraction contains both primary aerosol, placed directly in the ambient air (material of Earth's crust, dust emitted from industries, from roads), both aerosol of secondary origin (particles resulting from combustion, vapours of metals and organic compounds condensed). The fine fraction is responsible for most acidity and mutagenic activity of the particulates. In strongly antropization areas, the particulate arouses strong concern because of its obvious and proven negative effects on human health; the World Health Organization\ud
underline as the particulate material has influence on the population in a continuous way more than any other pollutant.\ud
In order to make a quantitative evaluation reliable is essential the knowledge of vertical distribution of particulate pollution, of composition and size distribution, and its evolution in time. While has increased enormously the availability of long series of meteorological data as the thermometric and pluviometric data, together with data of atmospheric pressure, sunshine and clouds, few historical series of aerosol concentrations in the atmosphere are available.\ud
Start point of this study was then the creation of a database of concentrations of TSP (total suspended particulate) and PM10 of Milano and its province over the\ud
last 30 years.\ud
For a good reconstruction of the historical series follows a statistical study of recovered data, including analysis of annual and seasonal trend of each monitoring station taken into account and the definition of optimal relationship between PM10/TSP for the correct homogenization of data.\ud
Ultimately we will try to study the influence of the wind on concentration of particulate matter: we know, in fact, that parameters such as the wind speed govern the dispersion and the removal of particulates in the atmosphere.\u