3,652 research outputs found

    Quantum probes to assess correlations in a composite system

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    We suggest and demonstrate experimentally a strategy to obtain relevant information about a composite system by only performing measurements on a small and easily accessible part of it, which we call quantum probe. We show in particular how quantitative information about the angular correlations of couples of entangled photons generated by spontaneous parametric down conversion is accessed through the study of the trace distance between two polarization states evolved from different initial conditions. After estimating the optimal polarization states to be used as quantum probe, we provide a detailed analysis of the connection between the increase of the trace distance above its initial value and the amount of angular correlations.Comment: 6 pages, 4 figure

    A large dynamic range radiation-tolerant analog memory in a quarter- micron CMOS technology

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    An analog memory prototype containing 8*128 cells has been designed in a commercial quarter-micron CMOS process. The aim of this work is to investigate the possibility of designing large dynamic range mixed-mode switched capacitor circuits for high-energy physics (HEP) applications in deep submicron CMOS technologies. Special layout techniques have been used to make the circuit radiation tolerant. The memory cells employ gate-oxide capacitors for storage, permitting a very high density. A voltage write-voltage read architecture has been chosen to minimize the sensitivity to absolute capacitor values. The measured input voltage range is 2.3 V (the power supply voltage V/sub DD/ is equal to 2.5 V), with a linearity of almost 8 bits over 2 V. The dynamic range is more than 11 bits. The pedestal variation is +or-0.5 mV peak-to-peak. The noise measured, which is dominated by the noise of the measurement setup, is around 0.8 mV rms. The characteristics of the memory have been measured before irradiation and after 100 kGy (SiO/sub 2/), and they do not degrade after irradiation. (15 refs)

    Environmental control on the end of the Dolomia Principale/Hauptdolomit depositional system in the central Alps: Coupling sea-level and climate changes

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    The Norian in the Western Tethys is characterised by the deposition of early-dolomitised inner platform facies (Dolomia Principale/Hauptdolomit, DP/HD), bordered on the landward side by terrigenous coastal deposits (Keuper) and on the seaward side by calcareous backreef and reefal facies (Dachstein Limestone) passing basinward to open-sea sediments (Hallstatt facies). The inner carbonate platform is locally (Lombardy Basin, Carnic Alps, Central Austroalpine) dissected by normal faults leading to the development of intraplatform troughs. Close to the Norian-Rhaetian boundary, sedimentation records an abrupt environmental change both on platform top and basins all over the Western Tethys (e.g. Western Carpathians, Transdanubian Range, Alps, Central Apennine). The top of the Dolomia Principale locally emerged, reflecting a major eustatic sea-level fall. Emersion is recorded in favourable settings by the development of polycyclic paleosols up to 30 m thick. In the Norian intraplatform basins, the succession is capped by 4 to 8 m of thin-bedded, fine-grained limestones yielding abundant remnants of fishes and terrestrial reptiles. Fossil concentration as well as sedimentological features is indicative of reduced sedimentation rates due to decreased carbonate production, induced by the emersion of the platform top. The sea-level fall was followed by deposition of mixed fine-grained siliciclastic-carbonate successions (e.g. Riva di Solto Shale, Kossen beds, "Rhaetavicula contorta beds", Fatra Formation). Stratigraphic evidence indicates a dry climate in the Western Tethys during the Norian, as indicated by the presence of evaporites (Burano, Apennine) and arid to semi-arid coastal to playa settings (Upper Keuper, Germany). In contrast, the basal layers of the basinal shales show evidence of wet climate. The end of the Norian depositional system records two different phenomena: (1) an important sea-level fall was responsible for the emersion of the platform top and deposition of a condensed horizon in the basins: and (2) transition from dry to humid climate. The observed evolution is explained with a global cooling which caused the rapid sea-level fall responsible for the abrupt end of the DP/HD depositional system and the shift of the boundary between arid and temperate climate belts, which modified the distribution and amount of rainfall, triggering the deposition of shales along the Western Tethys margin

    Optical Link of the Atlas Pixel Detector

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    The on-detector optical link of the ATLAS pixel detector contains radiation-hard receiver chips to decode bi-phase marked signals received on PIN arrays and data transmitter chips to drive VCSEL arrays. The components are mounted on hybrid boards (opto-boards). We present results from the irradiation studies with 24 GeV protons up to 32 Mrad (1.2 x 10^15 p/cm^2) and the experience from the production.Comment: 9th ICATPP Conference, Como, Ital

    Generalized convex hull construction for materials discovery

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    High-throughput computational materials searches generate large databases of locally-stable structures. Conventionally, the needle-in-a-haystack search for the few experimentally-synthesizable compounds is performed using a convex hull construction, which identifies structures stabilized by manipulation of a particular thermodynamic constraint (for example pressure or composition) chosen based on prior experimental evidence or intuition. To address the biased nature of this procedure we introduce a generalized convex hull framework. Convex hulls are constructed on data-driven principal coordinates, which represent the full structural diversity of the database. Their coupling to experimentally-realizable constraints hints at the conditions that are most likely to stabilize a given configuration. The probabilistic nature of our framework also addresses the uncertainty stemming from the use of approximate models during database construction, and eliminates redundant structures. The remaining small set of candidates that have a high probability of being synthesizable provide a much needed starting point for the determination of viable synthetic pathways.Comment: Accepted Manuscrip

    The First Year of the Large Hadron Collider: A Brief Review

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    The first year of LHC data taking provided an integrated luminosity of about 35/pb in proton-proton collisions at sqrt(s)=7 TeV. The accelerator and the experiments have demonstrated an excellent performance. The experiments have obtained important physics results in many areas, ranging from tests of the Standard Model to searches for new particles. Among other results the physics highlights have been the measurements of the W-, Z-boson and t t-bar production cross-sections, improved limits on supersymmetric and other hypothetical particles and the observation of jet-quenching, elliptical flow and J/Psi suppression in lead-lead collisions at sqrt(sNN) = 2.76 TeV.Comment: 11 pages, 9 figures, invited brief review for Mod. Phys. Lett.

    Performance of upstream interaction region detectors for the FIRST experiment at GSI

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    The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at GSI has been designed to study carbon fragmentation, measuring 12C double differential cross sections (∂2σ/ ∂θ∂E) for different beam energies between 100 and 1000 MeV/u. The experimental setup integrates newly designed detectors in the, so called, Interaction Region around the graphite target. The Interaction Region upstream detectors are a 250 μm thick scintillator and a drift chamber optimized for a precise measurement of the ions interaction time and position on the target. In this article we review the design of the upstream detectors along with the preliminary results of the data taking performed on August 2011 with 400 MeV/u fully stripped carbon ion beam at GSI. Detectors performances will be reviewed and compared to those obtained during preliminary tests, performed with 500 MeV electrons (at the BTF facility in the INFN Frascati Laboratories) and 80 MeV/u protons and carbon ions (at the INFN LNS Laboratories in Catania)

    Chemotherapy versus best supportive care in stage IV non-small cell lung cancer, non metastatic to the brain

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    Stage IV non-small cell lung cancer is a fatal disease, with a median survival of 14 months. Systemic chemotherapy is the most common approach. However the impact in overall survival and quality of life still a controversy. OBJECTIVES: To determine differences in overall survival and quality of life among patients with stage IV non-small cell lung cancer non-metastatic to the brain treated with best supportive care versus systemic chemotherapy. PATIENTS: From February 1990 through December 1995, 78 eligible patients were admitted with the diagnosis of stage IV non-small cell lung cancer . Patients were divided in 2 groups: Group A (n=31 -- treated with best supportive care ), and Group B (n=47 -- treated with systemic chemotherapy). RESULTS: The median survival time was 23 weeks (range 5 -- 153 weeks) in Group A and 55 weeks (range 7.4 -- 213 weeks) in Group B (p=0.0018). In both groups, the incidence of admission for IV antibiotics and need of blood transfusions were similar. Patients receiving systemic chemotherapy were also stratified into those receiving mytomycin, vinblastin, and cisplatinum, n=25 and those receiving other combination regimens (platinum derivatives associated with other drugs, n=22). Patients receiving mytomycin, vinblastin, and cisplatinum, n=25 had a higher incidence of febrile neutropenia and had their cycles delayed for longer periods of time than the other group. These patients also had a shorter median survival time (51 versus 66 weeks, p=0.005). CONCLUSION: In patients with stage IV non-small cell lung cancer, non-metastatic to the brain, chemotherapy significantly increases survival compared with best supportive care.O câncer de pulmão de células não pequenas em estádio IV é uma doença fatal, com uma sobrevida mediana de seis meses. Quimioterapia é a abordagem mais freqüente, apresentando um impacto na sobrevida controverso e questionável alteração na qualidade de vida. OBJETIVOS: Comparar o impacto na sobrevida global e na qualidade de vida em pacientes portadores de câncer de pulmão de células não pequenas, estádio IV, tratados com suporte clínico ou quimioterapia. PACIENTES: Entre fevereiro de 1990 e dezembro de 1995, 78 pacientes (pts) portadores de câncer de pulmão de células não pequenas estádio IV foram admitidos. Os pacientes foram divididos em dois grupos: grupo A (n=31 -- tratados com suporte clínico) e grupo B (n=47, tratados com quimioterapia). RESULTADOS: A sobrevida mediana no grupo tratado com suporte clínico foi de 23 semanas (variando de 5-153 semanas) e de 55 semanas no grupo tratado com quimioterapia (variando de 7,4 a 213 semanas), p= 0,0018 -- Qui-quadrada. Em ambos grupos, a incidência de internações hospitalares para a administração intravenosa de antibióticos e hemoderivados foi similar. Pacientes recebendo quimioterapia, foram estratificados entre àqueles que receberam mitomicina, vinblastina e cisplatina, n=25 e àqueles recebendo outros regimes (derivados de platina, associados à outras drogas, n= 22). Pacientes recebendo mitomicina, vinblastina e cisplatina, n=25 apresentaram uma incidência mais alta de neutropenia febril e tiveram atrasos mais longos entre os ciclos de quimioterapia, quando comparados aos pacientes do outro grupo. Pacientes recebendo mitomicina, vinblastina e cisplatina, n=25, também apresentaram uma pior sobrevida mediana (51 versus 66 semanas, p= 0,005 -- Qui-quadrado). CONCLUSÕES: Em pacientes com câncer de pulmão de células não pequenas, estádio IV, não metastático para os pulmões, o uso de quimioterapia aumenta a sobrevida de maneira estatisticamente significativa, quando comparado aos cuidados de suporte
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