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Search Results: 1 - 10 of 401279 matches for " M. Sacchi "
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Il Gel Piastrinico in chirurgia orale
Sacchi M.C.
Working Paper of Public Health , 2012,
Abstract: Obiettivi: L’utilizzo topico di emocomponenti autologhi, il concentrato piastrinico (CP) ed il plasma povero di piastrine, rappresenta una delle strategie più innovative per modulare ed amplificare i processi di guarigione e di rigenerazione tessutale. Con questo studio si è dimostrato che l’applicazione del gel piastrinico, quando viene applicato in chirurgia orale ed in particolare nell’implantologia, è in grado di migliorare ed accelerare i processi osteogenetici;Metodologia: il CP, preparato a partire da un prelievo contenuto di sangue venoso (30-60 ml), viene attivato mediante una miscela di calcio gluconato e batroxobina (un enzima similtrombinico). Nell’arco di 3-5 minuti si ottiene un bioprodotto pronto per rilasciare in situ, verosimilmente, quei GFs fondamentali per la guarigione e la rigenerazione dei tessuti circostanti.;Conclusioni: il gel piastrinico, una biotecnologia efficace, semplice e dai costi contenuti, offre ai clinici l’opportunità di poter disporre di uno strumento innovativo atto a ridurre i tempi di guarigione e le complicanze post-operative, migliorando notevolmente la qualità di vita dei pazienti;
Renormalized quantum tomography
G. M. D'Ariano,M. F. Sacchi
Physics , 2009, DOI: 10.1016/j.physleta.2009.11.081
Abstract: The core of quantum tomography is the possibility of writing a generally unbounded complex operator in form of an expansion over operators that are generally nonlinear functions of a generally continuous set of spectral densities--the so-called "quorum" of observables. The expansion is generally non unique, the non unicity allowing further optimization for given criteria. The mathematical problem of tomography is thus the classification of all such operator expansions for given (suitably closed) linear spaces of unbounded operators--e.g. Banach spaces of operators with an appropriate norm. Such problem is a difficult one, and remains still open, involving the theory of general basis in Banach spaces, a still unfinished chapter of analysis. In this paper we present new nontrivial operator expansions for the quorum of quadratures of the harmonic oscillator, and introduce a first very preliminary general framework to generate new expansions based on the Kolmogorov construction. The material presented in this paper is intended to be helpful for the solution of the general problem of quantum tomography in infinite dimensions, which corresponds to provide a coherent mathematical framework for operator expansions over functions of a continuous set of spectral densities.
Protocols for entanglement transformations of bipartite pure states
G. M. D'Ariano,M. F. Sacchi
Physics , 2002, DOI: 10.1103/PhysRevA.67.042312
Abstract: We present a general theoretical framework for both deterministic and probabilistic entanglement transformations of bipartite pure states achieved via local operations and classical communication. This framework unifies and greatly simplifies previous works. A necessary condition for ``pure contraction'' transformations is given. Finally, constructive protocols to achieve both probabilistic and deterministic entanglement transformations are presented.
LOCC protocols for entanglement transformations
G. M. D'Ariano,M. F. Sacchi
Physics , 2002,
Abstract: We construct the protocols to achieve probabilistic and deterministic entanglement transformations for bipartite pure states by means of local operations and classical communication. A new condition on pure contraction transformations is provided.
Optimized quantum-optical communications in the presence of loss
G. M. D'Ariano,M. F. Sacchi
Physics , 1997, DOI: 10.1016/S0030-4018(97)00688-3
Abstract: We consider the effect of loss on quantum-optical communication channels. The channel based on direct detection of number states, which for a lossless transmission line would achieve the ultimate quantum channel capacity, is easily degraded by loss. The same holds true for the channel based on homodyne detection of squeezed states, which also is very fragile to loss. On the contrary, the ``classical'' channel based on heterodyne detection of coherent states is loss-invariant. We optimize the a priori probability for the squeezed-state and the number-state channels, taking the effect of loss into account. In the low power regime we achieve a sizeable improvement of the mutual information, and both the squeezed-state and the number-state channels overcome the capacity of the coherent-state channel. In particular, the squeezed-state channel beats the classical channel for total average number of photons $N<8$. However, for sufficiently high power the classical channel always performs as the best one. For the number-state channel we show that with a loss $\eta\lesssim .6$ the optimized a priori probability departs from the usual thermal-like behavior, and develops gaps of zero probability, with a considerable improvement of the mutual information (up to 70 % of improvement at low power for attenuation $\eta=.15$).
Optical von Neumann measurement
G. M. D'Ariano,M. F. Sacchi
Physics , 1997, DOI: 10.1016/S0375-9601(97)00314-9
Abstract: We present an optical scheme that realizes the standard von Neumann measurement model, providing an indirect measurement of a quadrature of the field with controllable Gaussian state-reduction. The scheme is made of simple optical elements, as laser sources, beam splitters, and phase sensitive amplifiers, along with a feedback mechanism that uses a Pockels cell. We show that the von Neumann measurement is achieved without the need of working in a ultra-short pulsed regime.
Trace forms for the generalized Wigner functions
G. M. D'Ariano,M. F. Sacchi
Physics , 1997,
Abstract: We derive simple formulas connecting the generalized Wigner functions for $s$-ordering with the density matrix, and vice-versa. These formulas proved very useful for quantum mechanical applications, as, for example, for connecting master equations with Fokker-Planck equations, or for evaluating the quantum state from Monte Carlo simulations of Fokker-Planck equations, and finally for studying positivity of the generalized Wigner functions in the complex plane.
Quantum cloning optimal for joint measurements
G. M. D'Ariano,M. F. Sacchi
Physics , 2000,
Abstract: We show that universally covariant cloning is not optimal for achieving joint measurements of noncommuting observables with minimum added noise. For such a purpose a cloning transformation that is covariant with respect to a restricted transformation group is needed.
Two-mode heterodyne phase detection
G. M. D'Ariano,M. F. Sacchi
Physics , 2001, DOI: 10.1103/PhysRevA.52.R4309
Abstract: We present an experimental scheme that achieves ideal phase detection on a two-mode field. The two modes $a$ and $b$ are the signal and image band modes of an heterodyne detector, with the field approaching an eigenstate of the photocurrent $\hat{Z}=a+b^{\dag}$. The field is obtained by means of a high-gain phase-insensitive amplifier followed by a high-transmissivity beam-splitter with a strong local oscillator at the frequency of one of the two modes.
Entanglement at distance: qubits versus continuous variables
G. M. D'Ariano,M. F. Sacchi
Physics , 2002, DOI: 10.1002/prop.200310064
Abstract: We consider the problem of obtaining maximally entangled photon states at distance in the presence of loss. We compare the efficiency of two different schemes in establishing $N$ shared ebits: i) $N$ single ebit states with the qubit encoded on polarization; ii) a single continuous variable entangled state (emode) assisted by optimal local operation and classical communication (LOCC) protocol in order to obtain a $2^N$-dimensional maximally entangled state, with qubits encoded on the photon number.
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