326,645 research outputs found
Reconstituted CP29 : multicomponent fluorescence decay from an optically homogeneous sample
No full textThe multiexponential fluorescence decay of the CP29 complex in which the apoprotein and pigments were reconstituted in vitro was examined. Of the three decay components observed only the two dominant ones, with about 3 and 5 ns lifetimes, were studied. The main question addressed was whether the multicomponent decay was associated with sample optical heterogeneity. To this end, we examined the optical absorption and fluorescence of the CP29 sample by means of two different and independent experimental strategies. This approach was used as the wavelength positions of the absorption/fluorescence spectral forms has recently been shown to be a sensitive indicator of the binding site-induced porphyrin ring deformation (Zucchelli et al. Biophys J 93:2240-2254, 2007) and hence of apoprotein conformational changes. The data indicate that this CP29 sample is optically homogeneous. It is hypothesised that the different lifetimes are explained in terms of multiple detergent/CP29 interactions leading to different quenching states, a suggestion that allows for optical homogeneity
Molecola di acido nucleico funzionale e relativo uso
No full textViene descritta una molecola di acido nucleico funzionale trans-agente comprendente una sequenza di legame di bersaglio eucariotico comprendente una sequenza inversa complementare ad una sequenza di mRNA bersaglio per cui si deve migliorare la traduzione proteica e una sequenza regolatrice comprendente una sequenza di sito di entrata al ribosoma interno (IRES) o una sequenza derivata dal sito di ingresso del ribosoma interno (IRES) e una traduzione migliorativa della sequenza di mRNA bersaglio, in cui la sequenza regolatrice è posizionata a 3 'della sequenza di legame target
Relazioni del viaggio e missioni di Congo nell'Etiopia inferiore occidentale <dt.>
No full textVerfasser nach früheren Ausgaben ermittelt: Zucchelli, Antonio: Merckwuerdige Mißions- und Reise-Beschreibung nach Congo in EthiopienAutopsie nach dem Exemplar der ULB Sachsen-AnhaltPaginierfehler: Zählung sprint von S. 344 auf S. 369 und von S. 544 auf S. 553Vorlageform des Erscheinungsvermerks: Erfurth, Bey Johann Heydolph, 1723
Photoinhibition in vivo and in vitro involves weakly coupled chlorophyll-protein complexes
No full textIn the present study the analysis of the relation between the excited state population in the photosystem 11 (PSII) antenna and photoinactivation has been extended from an in vitro system, isolated thylakoids, to an in vivo system, Chlamydomonas reinhardtii cells. The results indicate that the excited state quenching by an added singlet quencher induces maximal protection against photoinhibition of about 30% of that expected on the basis of the observed light intensity-treatment time reciprocity rule. Similar results, obtained previously with thylakoids, have been interpreted in terms of damaged or incorrectly assembled complexes that play an important role in photoinhibition in the thylakoid membranes (Santabarbara, S., K. Neverov, F. M. Garlaschi, G. Zucchelli and R. C. Jennings [2001] Involvement of uncoupled antenna chlorophylls in photoinhibition in thylakoids. FEBS Lett. 491, 109-113.). In an attempt to better define this aspect, the photoinhibition action spectra were determined for mutant barley thylakoids, lacking the chlorophyll (Chl) a-b complexes of the outer antenna, and for its wild type. The results indicate that in both systems the action spectra are significantly blueshifted (2-4 nm) and are broader than the PSII absorption in the membranes. These data are interpreted in terms of a heterogeneous population of outer and inner antenna pigment-protein complexes that contain significant levels of uncoupled Chl
Logistica e mercato immobiliare in Italia
No full textLa globalizzazione dell'economia mondiale ha indotto un evidente rinnovamento delle caratteristiche dei mercati che regolano la competitività tra i "Sistemi Paese"; dalle pratiche manageriali delle imprese, orientate alla razionalizzazione delle risorse, all'esternalizzazione dei servizi no core, alla delocalizzazione manifatturiera, all'adozione di nuovi sistemi di comunicazione e movimentazione delle merci.
II settore della logistica è oggi uno dei comparti più complessi tra le attività economiche operanti nel nostro Paese; caratterizzato da processi trasversali e dalla cooperazione di un numero considerevole di attori, tale comparto è oggi in grado di esprimere un'efficiente gestione dell'intera catena del valore, operando su tre livelli spaziali concomitanti: economico, organizzativo e geografico. L'internazionalizzazione dei mercati e la delocalizzazione manifatturiera hanno dato avvio ad un processo di ridefinizione geografica dei flussi di merci, volto al superamento dei limiti e delle inefficienze della rete infrastrutturale nazionale, nella prospettiva di una totale integrazione con i progetti europei. L'Italia, in effetti, è da tempo inserita in un contesto logistico altamente competitivo, caratterizzato dal passaggio dei flussi commerciali tra Asia, Europa e Stati Uniti, che rende il nostro mercato particolarmente appetibile ad investitori nazionali ed internazionali.
Protagonisti di questa fase sono, da una parte i professionisti del Real Estate, ossia le società del "nuovo" mercato immobiliare che hanno come obiettivo l'individuazione delle aree, la progettazione, la costruzione, la vendita o la locazione degli "immobili della logistica". Dall'altra le società di servizi logistici che li affittano o, in alcuni casi, li acquistano per svolgere le proprie attività per conto di uno o più clienti. La competitività del nostro Sistema Paese passa dunque anche attraverso la capacità di offrire immobili "di qualità" e di coordinarne la localizzazione sul territorio (marketing territoriale).
In questo scenario, il libro approfondisce le dinamiche evolutive che hanno interessato il settore della logistica e le caratteristiche degli immobili e del relativo mercato immobiliare in Italia
Delamination localisation and length estimation in composite laminate beam by VSHM and pattern recognition methods
No full textThe focus of this work is to investigate the delamination damage in laminate composite beams, to fix a Vibration-based structural health monitoring (VSHM) method for the laminate structures. The analysis is concentrated on the vibration characteristics of the samples and, in particular, the attention is addressed on the first several natural frequencies of a composite laminate beam with a delamination damage. The core of this work is an experimental investigation on the vibration response of a composite laminate beam and its changes caused by delaminations with different sizes and in different locations of the beam. The study is divided in 3 sections: delamination detection, delamination localization, and delamination estimate. The aim is to determine how the first six harmonics frequencies change due to the delamination, and the results show that they can be successfully used to investigate the presence, the location and the dimensions of the delamination in a composite beam. A Pattern Recognition analysis is used to locate the damage, while the detection and the evaluation are done using the changes in the harmonic frequencies. A finite element analysis is performed, and the variations of the natural frequencies due to delamination are in good agreement with the experimental results
The Q(y) absorption transition of the light harvesting complex II as determined by structure based analysis of chlorophyll nmacrocycle deforemations
No full textThe absorption spectrum of the main antenna complex of photosystem II, LHCII, has been modeled using, as starting points, the chlorophyll (chl) atomic coordinates as obtained by the LHCII crystal analysis [Liu, Z., Yan, H., Wang, K., Kuang, T., Zhang, J., Gui, L., An, X., and Chang, W. (2004) Nature 428, 287-292] of three different trimers. The chl site Q(y) transition energies have been obtained in terms of the chl macrocycle deformations influencing the energy level of the chl frontier orbitals. Using these chl site transition energy values and the entire set of interaction energies, calculated in the ideal dipole approximation, the complete Hamiltonians for the three LHCII trimers have been written and the full set of 42 eigenstates of each LHCII trimer have been calculated. With the 42 transition energies and transition dipole strengths, either unperturbed or associated to the eigenstates, the LHCII Q(y) absorption spectrum has been calculated using a chl absorption band shape. These calculations have been performed both in vacuo and in the presence of a medium. Despite the number of approximations, a good correlation with the measured absorption spectrum of a LHCII preparation is obtained. This analysis shows that, although a substantial C3 symmetry of the LHCII trimer in terms of both chl-chl distances and interaction energies is present, a marked variation among monomer subsets of site transition energies is estimated. This leads to a C3 symmetry breaking in the unperturbed chl site transition energies set and, consequently, in the trimer eigenstates. It is also concluded that interactions among chlorophylls do not significantly modify the light absorption role of LHCII in plant leaves
Deciding Extensions of the Theory of Arrays by Integrating Decision Procedures and Instantiation Strategies
No full textThe theory of arrays, introduced by McCarthy in his seminal paper "Toward a mathematical science of computation", is central to Computer Science. Unfortunately, the theory alone is not sufficient
for many important verification applications such as program analysis. Motivated by this observation, we study extensions of the theory of
arrays whose satisfiability problem (i.e.\ checking the satisfiability of conjunctions of ground literals) is decidable. In particular, we
consider extensions where the indexes of arrays has the algebraic structure of Presburger Arithmetic and the theory of arrays is
augmented with axioms characterizing additional symbols such as dimension, sortedness, or the domain of definition of arrays.
We provide methods for integrating available decision procedures for the theory of arrays and Presburger Arithmetic with automatic instantiation strategies which allow us to reduce the satisfiability problem for the extension of the theory of arrays to that of the theories decided by the available procedures. Our approach aims to reuse as much as possible existing techniques so to ease the implementation of the proposed methods. To this end, we show how to use both model-theoretic and rewriting-based theorem proving (i.e., superposition) techniques to implement the instantiation strategies of the various extensions
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