35 research outputs found

    Quantum-noise--randomized data-encryption for WDM fiber-optic networks

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    We demonstrate high-rate randomized data-encryption through optical fibers using the inherent quantum-measurement noise of coherent states of light. Specifically, we demonstrate 650Mbps data encryption through a 10Gbps data-bearing, in-line amplified 200km-long line. In our protocol, legitimate users (who share a short secret-key) communicate using an M-ry signal set while an attacker (who does not share the secret key) is forced to contend with the fundamental and irreducible quantum-measurement noise of coherent states. Implementations of our protocol using both polarization-encoded signal sets as well as polarization-insensitive phase-keyed signal sets are experimentally and theoretically evaluated. Different from the performance criteria for the cryptographic objective of key generation (quantum key-generation), one possible set of performance criteria for the cryptographic objective of data encryption is established and carefully considered.Comment: Version 2: Some errors have been corrected and arguments refined. To appear in Physical Review A. Version 3: Minor corrections to version

    A autoridade, o desejo e a alquimia da política: linguagem e poder na constituição do papado medieval (1060-1120)

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    Long-term results of the treatment of aortic graft infection by in situ replacement with femoral popliteal vein grafts

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    ObjectiveGraft excision and neo-aortoiliac system (NAIS) reconstruction with large caliber, femoral popliteal vein (FPV) grafts have been reported as successful treatment of aortic graft infection (AGI) in several small series with limited follow-up. The goal of this study was to evaluate long-term outcomes in large cohort of consecutive patients treated with NAIS for AGI.MethodsFrom 1990 to 2006, 187 patients (age: 63 ± 10 years) with AGI were treated with in situ reconstructions using 336 FPV grafts. Data from a prospectively maintained data base were analyzed.ResultsNAIS reconstruction was performed for 144 infected aortofemoral bypasses, 21 infected aortic-iliac grafts, and 22 infected axillofemoral bypasses that had been placed to treat AGI. Polymicrobial cultures were present in 37% while 17% showed no growth. There were 55% gram positive, 32% gram negative, 13% anaerobic, and 18% fungal infections. The mean Society for Vascular Surgery run-off resistance score was 4.5 ± 2.3. Concomitant infrainguinal bypass was necessary in 27 (14%) patients (32 limbs). Major amputations were performed in 14 (7.4%) patients. Out of 14 amputations, five patients had irreversible ischemia and in four, there was no conduit available. Graft disruption from reinfection occurred in 10 patients (5%). While 30-day mortality was 10%, procedure-related mortality was 14%. Independent risk factors for perioperative death on multivariate analysis were: preoperative sepsis (odds ratio [OR] 3.5) ASA class 4 (OR 2.9), Candida species (OR 3.4), Candida glabrata (OR 7.6), Klebsiella pneumoniae (OR 3.5), and Bacteroides fragilis (OR 4.1). Perioperative factors included use of platelets (OR 2.4), blood loss >3.0 liters (OR 9.5). Cumulative primary patency at 72 months was 81%; secondary/assisted primary patency was 91%. Limb salvage at 72 months was 89%. Five-year survival was 52%.ConclusionsThese results compare favorably with other methods of treating AGI, especially in patients with multilevel occlusive disease. Principle advantages include acceptable perioperative mortality, low amputation rate, superior durability with excellent long-term patency, and freedom from secondary interventions and recurrent infections

    Message from general co-chairs and technical program co-chairs

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    Conference proceedings front matter may contain various advertisements, welcome messages, committee or program information, and other miscellaneous conference information. This may in some cases also include the cover art, table of contents, copyright statements, title-page or half title-pages, blank pages, venue maps or other general information relating to the conference that was part of the original conference proceedings.</p
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