1,107 research outputs found

    Quantum Reverse Shannon Theorem

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    Dual to the usual noisy channel coding problem, where a noisy (classical or quantum) channel is used to simulate a noiseless one, reverse Shannon theorems concern the use of noiseless channels to simulate noisy ones, and more generally the use of one noisy channel to simulate another. For channels of nonzero capacity, this simulation is always possible, but for it to be efficient, auxiliary resources of the proper kind and amount are generally required. In the classical case, shared randomness between sender and receiver is a sufficient auxiliary resource, regardless of the nature of the source, but in the quantum case the requisite auxiliary resources for efficient simulation depend on both the channel being simulated, and the source from which the channel inputs are coming. For tensor power sources (the quantum generalization of classical IID sources), entanglement in the form of standard ebits (maximally entangled pairs of qubits) is sufficient, but for general sources, which may be arbitrarily correlated or entangled across channel inputs, additional resources, such as entanglement-embezzling states or backward communication, are generally needed. Combining existing and new results, we establish the amounts of communication and auxiliary resources needed in both the classical and quantum cases, the tradeoffs among them, and the loss of simulation efficiency when auxiliary resources are absent or insufficient. In particular we find a new single-letter expression for the excess forward communication cost of coherent feedback simulations of quantum channels (i.e. simulations in which the sender retains what would escape into the environment in an ordinary simulation), on non-tensor-power sources in the presence of unlimited ebits but no other auxiliary resource. Our results on tensor power sources establish a strong converse to the entanglement-assisted capacity theorem.Comment: 35 pages, to appear in IEEE-IT. v2 has a fixed proof of the Clueless Eve result, a new single-letter formula for the "spread deficit", better error scaling, and an improved strong converse. v3 and v4 each make small improvements to the presentation and add references. v5 fixes broken reference

    Remote preparation of quantum states

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    Remote state preparation is the variant of quantum state teleportation in which the sender knows the quantum state to be communicated. The original paper introducing teleportation established minimal requirements for classical communication and entanglement but the corresponding limits for remote state preparation have remained unknown until now: previous work has shown, however, that it not only requires less classical communication but also gives rise to a trade-off between these two resources in the appropriate setting. We discuss this problem from first principles, including the various choices one may follow in the definitions of the actual resources. Our main result is a general method of remote state preparation for arbitrary states of many qubits, at a cost of 1 bit of classical communication and 1 bit of entanglement per qubit sent. In this "universal" formulation, these ebit and cbit requirements are shown to be simultaneously optimal by exhibiting a dichotomy. Our protocol then yields the exact trade-off curve for arbitrary ensembles of pure states and pure entangled states (including the case of incomplete knowledge of the ensemble probabilities), based on the recently established quantum-classical trade-off for quantum data compression. The paper includes an extensive discussion of our results, including the impact of the choice of model on the resources, the topic of obliviousness, and an application to private quantum channels and quantum data hiding.Comment: 21 pages plus 2 figures (eps), revtex4. v2 corrects some errors and adds obliviousness discussion. v3 has section VI C deleted and various minor oversights correcte

    Less sensitive oxygen-rich organic peroxides containing geminal hydroperoxy groups

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    Tetranitratoethane (C2H2N4O12), which has an oxygen content of 70.1% was synthesized by nitration of monomeric glyoxal using N2O5 and purified by sublimation. Single crystals could be grown from CH2Cl2/pentane and were used to determine the structure by X-ray diffraction. Several energetic parameters and values were also established

    Less sensitive oxygen-rich organic peroxides containing geminal hydroperoxy groups

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    Tetranitratoethane (C2H2N4O12), which has an oxygen content of 70.1% was synthesized by nitration of monomeric glyoxal using N2O5 and purified by sublimation. Single crystals could be grown from CH2Cl2/pentane and were used to determine the structure by X-ray diffraction. Several energetic parameters and values were also established

    Singular solutions of fully nonlinear elliptic equations and applications

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    We study the properties of solutions of fully nonlinear, positively homogeneous elliptic equations near boundary points of Lipschitz domains at which the solution may be singular. We show that these equations have two positive solutions in each cone of Rn\mathbb{R}^n, and the solutions are unique in an appropriate sense. We introduce a new method for analyzing the behavior of solutions near certain Lipschitz boundary points, which permits us to classify isolated boundary singularities of solutions which are bounded from either above or below. We also obtain a sharp Phragm\'en-Lindel\"of result as well as a principle of positive singularities in certain Lipschitz domains.Comment: 41 pages, 2 figure

    The Pathway to Low Outlier Status in Venous Thromboembolism Events: An Analysis of Pancreatic Surgery in ACS NSQIP

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    Introduction: Our institution’s hepatopancreaticobiliary service (HPBS) is a high-volume pancreatic surgery service, which has demonstrated consistently low rates of symptomatic venous thromboembolism (VTE) compared to similar institutions as reported by NSQIP. We sought to determine if the HPBS’s regimented multimodal VTE prophylaxis pathway plays a role in achieving consistently low VTE rates. Methods: We queried the ACS NSQIP Participant User File and our institution’s data from 2011-2016 for major pancreatic operations. We used Chi-squared analysis to compare the HPBS and national patient populations, and created a matched dataset based on preoperative patient factors. Univariate and multivariate analyses were performed on both the aggregate and matched data to determine independent risk factors for symptomatic VTE formation. Results: Among 36,435 NSQIP patients, 850 (2.3%) received surgery by the HPBS. VTE rates were significantly lower for the HPBS (2.0%) compared to the national cohort (3.5%) (p=0.018); this significance was seen in the matched cohort as well (p=0.040). Upon multivariate analysis, having an operation performed by the HPBS independently conferred lower odds of VTE formation in both the aggregate (OR=0.572, p=0.024) and matched (OR=0.530, p=0.041) cohorts. Discussion: The HPBS had statistically lower rates of symptomatic VTE compared to the national cohort as reported by NSQIP. We identified an independent protective effect of the HPBS on VTE formation, which we believe to be due, at least in part, to adherence to a high risk VTE prophylaxis pathway. This pathway could serve as a model for other institutions hoping to improve their VTE rates

    No. 7 - The Future of International Trade: An American Perspective

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    Organized and sponsored by the Dean Rusk Center for International Law and Policy and the University of Georgia’s Terry College of Business, along with the Business Law Society and Graduate Business Association, The Future of International Trade was a daylong conference exploring issues related to the business aspects of international trade, future challenges for trade, and the future of multilateral trade negotiations. Ambassador Demetrios Marantis, deputy U.S. trade representative, served as the keynote speaker for the event

    Severe Pneumococcal Pneumonia Causes Acute Cardiac Toxicity and Subsequent Cardiac Remodeling

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    Rationale: Up to one-third of patients hospitalized with pneumococcal pneumonia experience major adverse cardiac events (MACE) during or after pneumonia. In mice, Streptococcus pneumoniae caninvade themyocardium, induce cardiomyocyte death, and disrupt cardiac function following bacteremia, but it is unknown whether the same occurs in humans with severe pneumonia. Objectives: We sought to determine whether S. pneumoniae can (1) translocate the heart, (2) induce cardiomyocyte death, (3) causeMACE, and (4) induce cardiac scar formation after antibiotic treatment during severe pneumonia using a nonhuman primate (NHP) model. Methods: We examined cardiac tissue from six adult NHPs with severe pneumococcal pneumonia and three uninfected control animals. Three animals were rescued with antibiotics (convalescent animals). Electrocardiographic, echocardiographic, and serum biomarkers of cardiac damage were measured (troponin T, N-terminal pro-brain natriuretic peptide, and heart-type fatty acid binding protein). Histological examination included hematoxylin and eosin staining, immunofluorescence, immunohistochemistry, picrosirius red staining, and transmission electron microscopy. Immunoblots were used to assess the underlying mechanisms. Measurements and Main Results: Nonspecific ischemic alterations were detected by electrocardiography and echocardiography. Serum levels of troponin T and heart-type fatty acid binding protein were increased (P,0.05) after pneumococcal infection in both acutely ill and convalescent NHPs. S. pneumoniae was detected in the myocardium of all NHPs with acute severe pneumonia. Necroptosis and apoptosis were detected in the myocardium of both acutely ill and convalescent NHPs. Evidence of cardiac scar formation was observed only in convalescent animals by transmission electron microscopy and picrosirius red staining. Conclusions: S. pneumoniae invades the myocardium and induces cardiac injury with necroptosis and apoptosis, followed by cardiac scarring after antibiotic therapy, in anNHP model of severe pneumonia
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