10,661 research outputs found

    Teleportation scheme implementing contextually the Universal Optimal Quantum Cloning Machine and the Universal Not Gate. Complete experimental realization

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    By a significant modification of the standard protocol of quantum state Teleportation two processes ''forbidden'' by quantum mechanics in their exact form, the Universal NOT gate and the Universal Optimal Quantum Cloning Machine, have been implemented contextually and optimally by a fully linear method. In particular, the first experimental demonstration of the Tele-UNOT Gate, a novel quantum information protocol has been reported (cfr. quant-ph/0304070). A complete experimental realization of the protocol is presented here.Comment: 11 pages, 3 figure

    Geoneutrinos and reactor antineutrinos at SNO+

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    In the heart of the Creighton Mine near Sudbury (Canada), the SNO+ detector is foreseen to observe almost in equal proportion electron antineutrinos produced by U and Th in the Earth and by nuclear reactors. SNO+ will be the first long baseline experiment to measure a reactor signal dominated by CANDU cores (∼\sim55\% of the total reactor signal), which generally burn natural uranium. Approximately 18\% of the total geoneutrino signal is generated by the U and Th present in the rocks of the Huronian Supergroup-Sudbury Basin: the 60\% uncertainty on the signal produced by this lithologic unit plays a crucial role on the discrimination power on the mantle signal as well as on the geoneutrino spectral shape reconstruction, which can in principle provide a direct measurement of the Th/U ratio in the Earth.Comment: 7 pages including 2 figures and 1 table, in XIV International Conference on Topics in Astroparticle and Underground Physics (TAUP 2015) IOP Publishing , published on Journal of Physics: Conference Series 718 (2016) 06200

    IC 751: a new changing-look AGN discovered by NuSTAR

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    We present the results of five NuSTAR observations of the type 2 active galactic nucleus (AGN) in IC 751, three of which were performed simultaneously with XMM-Newton or Swift/XRT. We find that the nuclear X-ray source underwent a clear transition from a Compton-thick (N H≃2×1024 cm−2N_{\rm\,H}\simeq 2\times 10^{24}\rm\,cm^{-2}) to a Compton-thin (N H≃4×1023 cm−2N_{\rm\,H}\simeq 4\times 10^{23}\rm\,cm^{-2}) state on timescales of ≲3\lesssim 3 months, which makes IC 751 the first changing-look AGN discovered by NuSTAR. Changes of the line-of-sight column density at a ∼2σ\sim2\sigma level are also found on a time-scale of ∼48\sim 48 hours (ΔN H∼1023 cm−2\Delta N_{\rm\,H}\sim 10^{23}\rm\,cm^{-2}). From the lack of spectral variability on timescales of ∼100\sim 100 ks we infer that the varying absorber is located beyond the emission-weighted average radius of the broad-line region, and could therefore be related either to the external part of the broad-line region or a clumpy molecular torus. By adopting a physical torus X-ray spectral model, we are able to disentangle the column density of the non-varying absorber (N H∼3.8×1023 cm−2N_{\rm\,H}\sim 3.8\times 10^{23}\rm\,cm^{-2}) from that of the varying clouds [N H∼(1−150)×1022 cm−2N_{\rm\,H}\sim(1-150)\times10^{22}\rm\,cm^{-2}], and to constrain that of the material responsible for the reprocessed X-ray radiation (N H∼6×1024 cm−2N_{\rm\,H} \sim 6 \times 10^{24}\rm\,cm^{-2}). We find evidence of significant intrinsic X-ray variability, with the flux varying by a factor of five on timescales of a few months in the 2-10 and 10-50 keV band.Comment: Accepted for publication in ApJ, 11 pages, 6 figure

    Cluster derivation of Parisi's RSB solution for disordered systems

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    We propose a general scheme in which disordered systems are allowed to sacrifice energy equi-partitioning and separate into a hierarchy of ergodic sub-systems (clusters) with different characteristic time-scales and temperatures. The details of the break-up follow from the requirement of stationarity of the entropy of the slower cluster, at every level in the hierarchy. We apply our ideas to the Sherrington-Kirkpatrick model, and show how the Parisi solution can be {\it derived} quantitatively from plausible physical principles. Our approach gives new insight into the physics behind Parisi's solution and its relations with other theories, numerical experiments, and short range models.Comment: 7 pages 5 figure

    Stormy weather in 3C 196.1: nuclear outbursts and merger events shape the environment of the hybrid radio galaxy 3C 196.1

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    We present a multi-wavelength analysis based on archival radio, optical and X-ray data of the complex radio source 3C 196.1, whose host is the brightest cluster galaxy of a z=0.198z=0.198 cluster. HST data show Hα\alpha+[N II] emission aligned with the jet 8.4 GHz radio emission. An Hα\alpha+[N II] filament coincides with the brightest X-ray emission, the northern hotspot. Analysis of the X-ray and radio images reveals cavities located at galactic- and cluster- scales. The galactic-scale cavity is almost devoid of 8.4 GHz radio emission and the south-western Hα\alpha+[N II] emission is bounded (in projection) by this cavity. The outer cavity is co-spatial with the peak of 147 MHz radio emission, and hence we interpret this depression in X-ray surface brightness as being caused by a buoyantly rising bubble originating from an AGN outburst ∼\sim280 Myrs ago. A \textit{Chandra} snapshot observation allowed us to constrain the physical parameters of the cluster, which has a cool core with a low central temperature ∼\sim2.8 keV, low central entropy index ∼\sim13 keV cm2^2 and a short cooling time of ∼\sim500 Myr, which is <0.05<0.05 of the age of the Universe at this redshift. By fitting jumps in the X-ray density we found Mach numbers between 1.4 and 1.6, consistent with a shock origin. We also found compelling evidence of a past merger, indicated by a morphology reminiscent of gas sloshing in the X-ray residual image. Finally, we computed the pressures, enthalpies EcavE_{cav} and jet powers PjetP_{jet} associated with the cavities: Ecav∼7×1058E_{cav}\sim7\times10^{58} erg, Pjet∼1.9×1044P_{jet}\sim1.9\times10^{44} erg s−1^{-1} for the inner cavity and Ecav∼3×1060E_{cav}\sim3\times10^{60} erg, Pjet∼3.4×1044P_{jet}\sim3.4\times10^{44} erg s−1^{-1} for the outer cavity.Comment: 14 pages, 4 figures, ApJ accepte

    Testing the theory of grain growth and fragmentation by millimeter observations of protoplanetary disks

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    Context. Observations at sub-millimeter and mm wavelengths will in the near future be able to resolve the radial dependence of the mm spectral slope in circumstellar disks with a resolution of around a few AU at the distance of the closest star-forming regions. Aims. We aim to constrain physical models of grain growth and fragmentation by a large sample of (sub-)mm observations of disks around pre-main sequence stars in the Taurus-Auriga and Ophiuchus star-forming regions. Methods. State-of-the-art coagulation/fragmentation and disk-structure codes are coupled to produce steady-state grain size distributions and to predict the spectral slopes at (sub-)mm wavelengths. Results. This work presents the first calculations predicting the mm spectral slope based on a physical model of grain growth. Our models can quite naturally reproduce the observed mm-slopes, but a simultaneous match to the observed range of flux levels can only be reached by a reduction of the dust mass by a factor of a few up to about 30 while keeping the gas mass of the disk the same. This dust reduction can either be due to radial drift at a reduced rate or during an earlier evolutionary time (otherwise the predicted fluxes would become too low) or due to efficient conversion of dust into larger, unseen bodies.Comment: Accepted for publication in A&A Letters. 5 pages, 3 figure

    Glassy Critical Points and Random Field Ising Model

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    We consider the critical properties of points of continuous glass transition as one can find in liquids in presence of constraints or in liquids in porous media. Through a one loop analysis we show that the critical Replica Field Theory describing these points can be mapped in the Ï•4\phi^4-Random Field Ising Model. We confirm our analysis studying the finite size scaling of the pp-spin model defined on sparse random graph, where a fraction of variables is frozen such that the phase transition is of a continuous kind.Comment: The paper has been completely revised. A completely new part with simulations of a p-spin glass model on random graph has been included. An appendix with the Mathematica worksheet used in the calculation of the diagrams has also been adde

    Research on Long-Term Care Homes for Older People in Brazil: Protocol for Scoping Review

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    LOTUS CONSORTIUM - Improving care in Long-term Care Institutions in Brazil and Europe through Collaboration and ResearchBackground The fast growth of the ageing population in low and middle-income countries, such as Brazil, has allowed little time for social and health care systems to adapt. As the care needs for the most vulnerable and frail older people become increasingly complex, services and governments need to ensure that long term care homes deliver high-quality and evidence-based care to meet their healthcare needs. Aim To examine and map the range of research undertaken in Brazil regarding care homes published in peer reviewed journals. Method This scoping review will consider all relevant peer-reviewed primary studies fully or partly conducted in Brazilian care homes including those which consider workforce (for example, e.g. healthcare professionals, care staff, and management level staff) and care home residents (older people aged 60 years and above), using empirical and original research focused on any health related topic. The searches will be conducted using bibliographic databases (MEDLINE, EMBASE, LILACS and Google Scholar) and manual searching of the reference lists of relevant studies published in English, Portuguese or Spanish from inception up to 2018. Two authors will independently screen each document by title and abstract against the eligibility criteria. In case of disagreement, a third reviewer will be consulted. Data from the included studies will be extracted and reported using tables, graphs, and narrative accounts using elements of content analysis. The Mixed Methods Appraisal Tool will be used to appraise the methodological quality of the included studies

    Properties of Stationary Nonequilibrium States in the Thermostatted Periodic Lorentz Gas II: The many point particles system

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    We study the stationary nonequilibrium states of N point particles moving under the influence of an electric field E among fixed obstacles (discs) in a two dimensional torus. The total kinetic energy of the system is kept constant through a Gaussian thermostat which produces a velocity dependent mean field interaction between the particles. The current and the particle distribution functions are obtained numerically and compared for small E with analytic solutions of a Boltzmann type equation obtained by treating the collisions with the obstacles as random independent scatterings. The agreement is surprisingly good for both small and large N. The latter system in turn agrees with a self consistent one particle evolution expected to hold in the limit of N going to infinity.Comment: 14 pages, 9 figure
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