9,477 research outputs found

    Harvesting Entities from the Web Using Unique Identifiers -- IBEX

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    In this paper we study the prevalence of unique entity identifiers on the Web. These are, e.g., ISBNs (for books), GTINs (for commercial products), DOIs (for documents), email addresses, and others. We show how these identifiers can be harvested systematically from Web pages, and how they can be associated with human-readable names for the entities at large scale. Starting with a simple extraction of identifiers and names from Web pages, we show how we can use the properties of unique identifiers to filter out noise and clean up the extraction result on the entire corpus. The end result is a database of millions of uniquely identified entities of different types, with an accuracy of 73--96% and a very high coverage compared to existing knowledge bases. We use this database to compute novel statistics on the presence of products, people, and other entities on the Web.Comment: 30 pages, 5 figures, 9 tables. Complete technical report for A. Talaika, J. A. Biega, A. Amarilli, and F. M. Suchanek. IBEX: Harvesting Entities from the Web Using Unique Identifiers. WebDB workshop, 201

    Modeling Quantum Optical Components, Pulses and Fiber Channels Using OMNeT++

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    Quantum Key Distribution (QKD) is an innovative technology which exploits the laws of quantum mechanics to generate and distribute unconditionally secure cryptographic keys. While QKD offers the promise of unconditionally secure key distribution, real world systems are built from non-ideal components which necessitates the need to model and understand the impact these non-idealities have on system performance and security. OMNeT++ has been used as a basis to develop a simulation framework to support this endeavor. This framework, referred to as "qkdX" extends OMNeT++'s module and message abstractions to efficiently model optical components, optical pulses, operating protocols and processes. This paper presents the design of this framework including how OMNeT++'s abstractions have been utilized to model quantum optical components, optical pulses, fiber and free space channels. Furthermore, from our toolbox of created components, we present various notional and real QKD systems, which have been studied and analyzed.Comment: Published in: A. F\"orster, C. Minkenberg, G. R. Herrera, M. Kirsche (Eds.), Proc. of the 2nd OMNeT++ Community Summit, IBM Research - Zurich, Switzerland, September 3-4, 201

    A second eigenvalue bound for the Dirichlet Schroedinger operator

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    Let λi(Ω,V)\lambda_i(\Omega,V) be the iith eigenvalue of the Schr\"odinger operator with Dirichlet boundary conditions on a bounded domain ΩRn\Omega \subset \R^n and with the positive potential VV. Following the spirit of the Payne-P\'olya-Weinberger conjecture and under some convexity assumptions on the spherically rearranged potential VV_\star, we prove that λ2(Ω,V)λ2(S1,V)\lambda_2(\Omega,V) \le \lambda_2(S_1,V_\star). Here S1S_1 denotes the ball, centered at the origin, that satisfies the condition λ1(Ω,V)=λ1(S1,V)\lambda_1(\Omega,V) = \lambda_1(S_1,V_\star). Further we prove under the same convexity assumptions on a spherically symmetric potential VV, that λ2(BR,V)/λ1(BR,V)\lambda_2(B_R, V) / \lambda_1(B_R, V) decreases when the radius RR of the ball BRB_R increases. We conclude with several results about the first two eigenvalues of the Laplace operator with respect to a measure of Gaussian or inverted Gaussian density

    Optical imaging of resonant electrical carrier injection into individual quantum dots

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    We image the micro-electroluminescence (EL) spectra of self-assembled InAs quantum dots (QDs) embedded in the intrinsic region of a GaAs p-i-n diode and demonstrate optical detection of resonant carrier injection into a single QD. Resonant tunneling of electrons and holes into the QDs at bias voltages below the flat-band condition leads to sharp EL lines characteristic of individual QDs, accompanied by a spatial fragmentation of the surface EL emission into small and discrete light- emitting areas, each with its own spectral fingerprint and Stark shift. We explain this behavior in terms of Coulomb interaction effects and the selective excitation of a small number of QDs within the ensemble due to preferential resonant tunneling paths for carriers.Comment: 4 page

    Comparative imipenem treatment of Staphylococcus aureus endocarditis in the rat

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    The efficacy of imipenem alone or in association with gentamicin against Staphylococcus aureus experimental endocarditis was compared to the efficacy of cloxacillin alone or in association with gentamicin. Parenteral treatment was started 24 h after intravenous bacterial challenge of rats with catheter-induced aortic valve vegetations. The cloxacillin MIC and MBC for Staph. aureus were 0.125 and 32 mg/l and the imipenem MIC and MBC 0.008 and 8 mg/l, respectively. In-vitro killing curves showed a synergistic effect between cloxacillin and gentamicin, and an additive effect between imipenem and gentamicin. Only large doses of cloxacillin (400 mg/kg tid) (producing serum levels above those obtained after intravenous injection of 2 g in man) achieved results comparable to those of imipenem 80 mg/kg tid (producing serum levels similar to those obtained after an intravenous dose of 750 mg in man) in reducing the bacterial numbers in vegetations after 3 and 5 days of treatment. There was a significantly greater reduction of bacterial numbers in vegetations after treatment with the association of cloxacillin and gentamicin than with cloxacillin alone. In contrast, the addition of gentamicin to imipenem did not improve significantly the results of treatment with imipenem alone, but imipenem alone was as good as the combination cloxacillin and gentamicin after 5 days of treatment. We conclude that imipenem is a highly bactericidal drug in this animal model, worth considering for clinical trials in the treatment of Staph. aureus infection

    Gene identification for the cblD defect of vitamin B12 metabolism

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    Background Vitamin B12 (cobalamin) is an essential cofactor in several metabolic pathways. Intracellular conversion of cobalamin to its two coenzymes, adenosylcobalamin in mitochondria and methylcobalamin in the cytoplasm, is necessary for the homeostasis of methylmalonic acid and homocysteine. Nine defects of intracellular cobalamin metabolism have been defined by means of somatic complementation analysis. One of these defects, the cblD defect, can cause isolated methylmalonic aciduria, isolated homocystinuria, or both. Affected persons present with multisystem clinical abnormalities, including developmental, hematologic, neurologic, and metabolic findings. The gene responsible for the cblD defect has not been identified. Methods We studied seven patients with the cblD defect, and skin fibroblasts from each were investigated in cell culture. Microcell-mediated chromosome transfer and refined genetic mapping were used to localize the responsible gene. This gene was transfected into cblD fibroblasts to test for the rescue of adenosylcobalamin and methylcobalamin synthesis. Results The cblD gene was localized to human chromosome 2q23.2, and a candidate gene, designated MMADHC (methylmalonic aciduria, cblD type, and homocystinuria), was identified in this region. Transfection of wild-type MMADHC rescued the cellular phenotype, and the functional importance of mutant alleles was shown by means of transfection with mutant constructs. The predicted MMADHC protein has sequence homology with a bacterial ATP-binding cassette transporter and contains a putative cobalamin binding motif and a putative mitochondrial targeting sequence. Conclusions Mutations in a gene we designated MMADHC are responsible for the cblD defect in vitamin B12 metabolism. Various mutations are associated with each of the three biochemical phenotypes of the disorder

    Controversies in the Use of Passive Immunotherapy for Bacterial Infections in the Critically Ill Patient

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    Several preparations of standard immunoglobulins for intravenous use have been tested as adjunctive therapy for bacterial infections in premature neonates and in critically ill adults after major surgery, trauma, and burn. The use of intravenous immunoglobulins in these settings is controversial because the efficacy and cost-effectiveness of this treatment are still not definitively established. Specific preparations of immunoglobulins against Pseudomonas aeruginosa for intramuscular administration have shown promising efficacy, and preparations for intravenous administration are now under investigation. Cross-protection against a wide range of gram-negative infections has been attempted by the administration of antiserum to the core glycolipid of lipopolysaccharide prepared from volunteers immunized with the J5 mutant of Escherichia coli 0111. Treatment with this preparation improved the survival rate of patients with gram-negative bacteremia and, when administered prophylactically to high-risk surgical patients, prevented shock and death related to gram-negative infections. The mechanism of protection of the J5 antiserum is not clearly understood because of our inability to measure the actual protective antibody in polyclonal J5 antiserum. Thus, the preparation of readily available cross-protective hyperimmune immunoglobulins is hampered because there is presently no method of selecting appropriate donors or high-titered plasma pool
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