Suppression of decoherence in quantum registers by entanglement with a nonequilibrium environment

It is shown that a nonequilibrium environment can be instrumental in suppressing decoherence between distinct decoherence free subspaces in quantum registers. The effect is found in the framework of exact coherent-product solutions for model registers decohering in a bath of degenerate harmonic modes, through couplings linear in bath coordinates. These solutions represent a natural nonequilibrium extension of the standard solution for a decoupled initial register state and a thermal environment. Under appropriate conditions, the corresponding reduced register distribution can propagate in an unperturbed manner, even in the presence of entanglement between states belonging to distinct decoherence free subspaces, and despite persistent bath entanglement. As a byproduct, we also obtain a refined picture of coherence dynamics under bang-bang decoherence control. In particular, it is shown that each radio-frequency pulse in a typical bang-bang cycle induces a revival of coherence, and that these revivals are exploited in a natural way by the time-symmetrized version of the bang-bang protocol.Comment: RevTex3, 26 pgs., 2 figs.. This seriously expanded version accepted by Phys.Rev.A. No fundamentally new content, but rewritten introduction to problem, self-contained introduction of thermal coherent-product states in standard operator formalism, examples of zero-temperature decoherence free Davydov states. Also fixed a typo that propagated into an interpretational blunder in old Sec.3 [fortunately of no consequence

On the robustness of bucket brigade quantum RAM

We study the robustness of the bucket brigade quantum random access memory model introduced by Giovannetti, Lloyd, and Maccone [Phys. Rev. Lett. 100, 160501 (2008)]. Due to a result of Regev and Schiff [ICALP '08 pp. 773], we show that for a class of error models the error rate per gate in the bucket brigade quantum memory has to be of order $o(2^{-n/2})$ (where $N=2^n$ is the size of the memory) whenever the memory is used as an oracle for the quantum searching problem. We conjecture that this is the case for any realistic error model that will be encountered in practice, and that for algorithms with super-polynomially many oracle queries the error rate must be super-polynomially small, which further motivates the need for quantum error correction. By contrast, for algorithms such as matrix inversion [Phys. Rev. Lett. 103, 150502 (2009)] or quantum machine learning [Phys. Rev. Lett. 113, 130503 (2014)] that only require a polynomial number of queries, the error rate only needs to be polynomially small and quantum error correction may not be required. We introduce a circuit model for the quantum bucket brigade architecture and argue that quantum error correction for the circuit causes the quantum bucket brigade architecture to lose its primary advantage of a small number of "active" gates, since all components have to be actively error corrected.Comment: Replaced with the published version. 13 pages, 9 figure

Assume-Guarantee Abstraction Refinement for Probabilistic Systems

We describe an automated technique for assume-guarantee style checking of strong simulation between a system and a specification, both expressed as non-deterministic Labeled Probabilistic Transition Systems (LPTSes). We first characterize counterexamples to strong simulation as "stochastic" trees and show that simpler structures are insufficient. Then, we use these trees in an abstraction refinement algorithm that computes the assumptions for assume-guarantee reasoning as conservative LPTS abstractions of some of the system components. The abstractions are automatically refined based on tree counterexamples obtained from failed simulation checks with the remaining components. We have implemented the algorithms for counterexample generation and assume-guarantee abstraction refinement and report encouraging results.Comment: 23 pages, conference paper with full proof

A Variational Procedure for Time-Dependent Processes

A simple variational Lagrangian is proposed for the time development of an arbitrary density matrix, employing the "factorization" of the density. Only the "kinetic energy" appears in the Lagrangian. The formalism applies to pure and mixed state cases, the Navier-Stokes equations of hydrodynamics, transport theory, etc. It recaptures the Least Dissipation Function condition of Rayleigh-Onsager {\bf and in practical applications is flexible}. The variational proposal is tested on a two level system interacting that is subject, in one instance, to an interaction with a single oscillator and, in another, that evolves in a dissipative mode.Comment: 25 pages, 4 figure

Topology of amorphous tetrahedral semiconductors on intermediate lengthscales

Using the recently-proposed ``activation-relaxation technique'' for optimizing complex structures, we develop a structural model appropriate to a-GaAs which is almost free of odd-membered rings, i.e., wrong bonds, and possesses an almost perfect coordination of four. The model is found to be superior to structures obtained from much more computer-intensive tight-binding or quantum molecular-dynamics simulations. For the elemental system a-Si, where wrong bonds do not exist, the cost in elastic energy for removing odd-membered rings is such that the traditional continuous-random network is appropriate. Our study thus provides, for the first time, direct information on the nature of intermediate-range topology in amorphous tetrahedral semiconductors.Comment: 4 pages, Latex and 2 postscript figure

Line orientation adaptation: local or global?

Prolonged exposure to an oriented line shifts the perceived orientation of a subsequently observed line in the opposite direction, a phenomenon known as the tilt aftereffect (TAE). Here we consider whether the TAE for line stimuli is mediated by a mechanism that integrates the local parts of the line into a single global entity prior to the site of adaptation, or the result of the sum of local TAEs acting separately on the parts of the line. To test between these two alternatives we used the fact the TAE transfers almost completely across luminance contrast polarity [1]. We measured the TAE using adaptor and test lines that (1) either alternated in luminance polarity or were of a single polarity, and (2) either alternated in local orientation or were of a single orientation. We reasoned that if the TAE was agnostic to luminance polarity and was parts-based, we should obtain large TAEs using alternating-polarity adaptors with single-polarity tests. However we found that (i) TAEs using one-alternating-polarity adaptors with all-white tests were relatively small, increased slightly for two-alternating-polarity adaptors, and were largest with all-white or all-black adaptors. (ii) however TAEs were relatively large when the test was one-alternating polarity, irrespective of the adaptor type. (iii) The results with orientation closely mirrored those obtained with polarity with the difference that the TAE transfer across orthogonal orientations was weak. Taken together, our results demonstrate that the TAE for lines is mediated by a global shape mechanism that integrates the parts of lines into whole prior to the site of orientation adaptation. The asymmetry in the magnitude of TAE depending on whether the alternating-polarity lines was the adaptor or test can be explained by an imbalance in the population of neurons sensitive to 1st-and 2nd-order lines, with the 2nd-order lines being encoded by a subset of the mechanisms sensitive to 1st-order lines

From Davydov solitons to decoherence-free subspaces: self-consistent propagation of coherent-product states

The self-consistent propagation of generalized $D_{1}$ [coherent-product] states and of a class of gaussian density matrix generalizations is examined, at both zero and finite-temperature, for arbitrary interactions between the localized lattice (electronic or vibronic) excitations and the phonon modes. It is shown that in all legitimate cases, the evolution of $D_{1}$ states reduces to the disentangled evolution of the component $D_{2}$ states. The self-consistency conditions for the latter amount to conditions for decoherence-free propagation, which complement the $D_{2}$ Davydov soliton equations in such a way as to lift the nonlinearity of the evolution for the on-site degrees of freedom. Although it cannot support Davydov solitons, the coherent-product ansatz does provide a wide class of exact density-matrix solutions for the joint evolution of the lattice and phonon bath in compatible systems. Included are solutions for initial states given as a product of a [largely arbitrary] lattice state and a thermal equilibrium state of the phonons. It is also shown that external pumping can produce self-consistent Frohlich-like effects. A few sample cases of coherent, albeit not solitonic, propagation are briefly discussed.Comment: revtex3, latex2e; 22 pages, no figs.; to appear in Phys.Rev.E (Nov.2001

OP0251 THE EULAR SYSTEMIC SCLEROSIS IMPACT OF DISEASE (SCLEROID) SCORE – A NEW PATIENT-REPORTED OUTCOME MEASURE FOR PATIENTS WITH SYSTEMIC SCLEROSIS

Background:Patient reported outcome measures (PROM) are important for clinical practice and research. Given the unmet need for a comprehensive PROM for systemic sclerosis (SSc), the ScleroID questionnaire was developed by a joint team of patients with SSc and medical experts. This is intended as a brief, specific, patient-derived, disease impact score for research and clinical use in SSc.Objectives:Here, we present the validation and final version of the ScleroID.Methods:This EULAR-endorsed project involves 9 European expert SSc centers. Patients fulfilling the ACR/EULAR 2013 criteria were prospectively included since 05/16 in a large observational cohort study. Patients completed the ScleroID and comparators SHAQ, EQ5D, SF36. They also weighted the 10 dimensions of the ScleroID by distributing 100 points according to the perceived impact on their health. The final score calculation is based on the ranking of the weights. The validation study included a reliability arm and a longitudinal arm, looking at sensitivity to change at follow-up.Results:Of the 472 patients included at baseline, 109 patients also had a reliability visit and 113 patients a follow-up visit. 84.5% of patients were female, 29.8% had diffuse SSc, mean age was 54.6 years, and mean disease duration 9.5 years. The highest weights were assigned by the patients to Raynaud`s phenomenon, fatigue, hand function and pain, confirming our previous results. The total ScleroID score showed good Spearman correlation coefficients with the comparators (SHAQ, 0.73; EQ5D -0.48; Patient's global assessment, VAS 0.77; HAQ-DI 0.62; SF36 physical score -0.62; each p<0.001). The internal consistency was good: Crohnbach's alpha 0.866, similar to SS-HAQ (0.88) and higher than EQ5D (0.77). The ScleroID had a very good reliability: intra-class correlation coefficient 0.839 (ranging 0.608 to 0.788 for the individual items), superior to all comparators. Twenty of 113 patients reported a change in their disease status at follow up. Sensitivity to change: the standardized response mean was 0.34 for the total ScleroID score and highest for lower GI (0.633) and life choices domains (0.521), superior to all other PROM. Figure 1 shows the final ScleroID.Figure 1.Conclusion:The EULAR ScleroID is a novel PROM designed for use in clinical practice and clinical trials to reflect the disease impact of SSc, showing good performance in the validation study. Importantly, Raynaud syndrome, impaired hand function, pain and fatigue were the main patient reported drivers of disease impact.Disclosure of Interests:Mike O. Becker: None declared, Rucsandra Dobrota: None declared, Kim Fligelstone: None declared, Annelise Roennow: None declared, Yannick Allanore Grant/research support from: BMS, Inventiva, Roche, Sanofi, Consultant of: Actelion, Bayer AG, BMS, BI, Patricia Carreira Grant/research support from: Actelion, Roche, MSD, Consultant of: GlaxoSmithKline, VivaCell Biotechnology, Emerald Health Pharmaceuticals, Boehringer Ingelheim, Roche, Speakers bureau: Actelion, GlaxoSmithKline, Roche, László Czirják Consultant of: Actelion, BI, Roche-Genentech, Lilly, Medac, Novartis, Pfizer, Bayer AG, Christopher Denton Grant/research support from: GlaxoSmithKline, CSL Behring, and Inventiva, Consultant of: Medscape, Roche-Genentech, Actelion, GlaxoSmithKline, Sanofi Aventis, Inventiva, CSL Behring, Boehringer Ingelheim, Corbus Pharmaceuticals, Acceleron, Curzion and Bayer, Roger Hesselstrand: None declared, Gunnel Sandqvist: None declared, Otylia Kowal-Bielecka Consultant of: Bayer, Boehringer Ingelheim, Inventiva, MSD, Medac, Novartis, Roche and Sandoz, Speakers bureau: Bayer, Boehringer Ingelheim, Inventiva, MSD, Medac, Novartis, Roche and Sandoz, Cosimo Bruni Speakers bureau: Actelion, Eli Lilly, Marco Matucci Cerinic: None declared, Carina Mihai: None declared, Ana Maria Gheorghiu: None declared, Ulf Müller-Ladner Speakers bureau: Biogen, Joe Sexton: None declared, Turid Heiberg: None declared, Oliver Distler Grant/research support from: Grants/Research support from Actelion, Bayer, Boehringer Ingelheim, Competitive Drug Development International Ltd. and Mitsubishi Tanabe; he also holds the issued Patent on mir-29 for the treatment of systemic sclerosis (US8247389, EP2331143)., Consultant of: Consultancy fees from Actelion, Acceleron Pharma, AnaMar, Bayer, Baecon Discovery, Blade Therapeutics, Boehringer, CSL Behring, Catenion, ChemomAb, Curzion Pharmaceuticals, Ergonex, Galapagos NV, GSK, Glenmark Pharmaceuticals, Inventiva, Italfarmaco, iQvia, medac, Medscape, Mitsubishi Tanabe Pharma, MSD, Roche, Sanofi and UCB, Speakers bureau: Speaker fees from Actelion, Bayer, Boehringer Ingelheim, Medscape, Pfizer and Roch

Reconstructia sanului dupa diferitele proceduri chirurgicale adresate cancerului mamar

Spitalul Clinic de Urgenţă “Bagdasar-Arseni” Bucureşti, România, Spitalul Clinic de urgenţă “Sf. Pantelimon” Bucureşti, România, Spitalul Judeţean de Urgenţă Piteşti, România, Al XI-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova și cea de-a XXXIII-a Reuniune a Chirurgilor din Moldova „Iacomi-Răzeșu” 27-30 septembrie 2011Introducere. Dintre neoplaziile intalnite la femeie, cancerul mamar o reprezinta pe cea mai frecventa incidenta acestuia fiind in crestere in ultimele decenii. Chirurgia de conservare a sanului este acum larg acceptata drept tratamentul de electie in cancerul mamar.Actualmente, cancerul mamar este abordat in echipe pluridisciplinare, reconstructia dupa diferitele tipuri de interventii de exereza fiind preferata in majoritatea cazurilor. Se are in vedere reconstructia volumului sanului, simetrizarea sanului nou format cu cel controlateral si reconstructia placii areolo-mamare. Material si metoda. Lucrarea de fata are la baza studiul retrospectiv al unui numar de 7 cazuri de cancer mamar tratate in Spitalul Clinic de Urgenta “Bagdasar-Arseni” in intervalul Iunie 2008 – Iunie 2011. Au fost luate in calcul atat cazurile la care s-au facut in cadrul aceleasi interventii chirurgicale, cat si cazurile la care reconstructia s-a facut la un anumit interval distanta.Rezultate. Rezultatele au fost bune in cadrul ambelor tehnici – reconstructie imediata dupa ablatie si reconstructie la distanta – insa procentul complicatiilor asociate a fost mai mare pentru reconstructia la distanta, in mare masura datorita remanierilor tisulare aparute intre cele doua interventii chirurgicale. Mortalitatea a fost 0, iar in cadrul morbiditatii am intalnit un caz cu necroza parcelara ce a necesitat o reinterventie pentru grefare si un caz de limforagie persistenta, care odata devenit cronic, a necesitat indepartarea protezei de silicon. Concluzii.-Tehnica de reconstructie este una dificila si minutioasa, al carui rezultat favorabil este dependent atat de alegerea unei tehnici de ablatie potrivita urmata de una de reconstructie individuala cat si de colaborarea interdisciplinara intre chirurgul de chirurgie generala, chirurgul plastician si medicul oncolog- In urma cazurilor prezentate si a rezultatelor foarte bune obtinute optam pentru reconstructia imediata urmata de tratamentul chimioterapeutic specific.-Din experienta noastra consideram extrem de importante indicatia chirurgicala, tehnica pentru care se opteaza, acordul asupra abordului utilizat al membrilor echipei pluridisciplinare si urmarirea postoperatorie atenta

The GEYSERS optical testbed: a platform for the integration, validation and demonstration of cloud-based infrastructure services

The recent evolution of cloud services is leading to a new service transformation paradigm to accommodate network infrastructures in a cost-scalable way. In this transformation, the network constitutes the key to efficiently connect users to services and applications. In this paper we describe the deployment, validation and demonstration of the optical integrated testbed for the “GEneralized architecture for dYnamic infrastructure SERviceS” (GEYSERS) project to accommodate such cloud based Infrastructure Services. The GEYSERS testbed is composed of a set of local physical testbeds allocated in the facilities of the GEYSERS partners. It is built up based on the requirements specification, architecture definition and per-layer development that constitutes the whole GEYSERS ecosystem, and validates the procedures on the GEYSERS prototypes. The testbed includes optical devices (layer 1), switches (layer 2), and IT resources deployed in different local testbeds provided by the project partners and interconnected among them to compose the whole testbed layout. The main goal of the GEYSERS testbed is twofold. On one hand, it aims at providing a validation ground for the architecture, concepts and business models proposed by GEYSERS, sustained by two main paradigms: Infrastructure as a Service (IaaS) and the coupled provisioning of optical network and IT resources. On the other hand, it is used as a demonstration platform for testing the software prototypes within the project and to demonstrate to the research and business community the project approach and solutions. In this work, we discuss our experience in the deployment of the testbed and share the results and insights learned from our trials in the process. Additionally, the paper highlights the most relevant experiments carried out in the testbed, aimed at the validation of the overall GEYSERS architecture