266 research outputs found

    Biosafety and risk assessment in the use of genetically modified mosquitoes for disease control

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    The development and implementation of the release of genetically modified mosquitoes (GMM) for interrupting pathogen transmission represent a major challenge, despite the fact that several achievements have been made about Anopheles and Aedes mosquitoes. There are major biotechnology challenges remaining about the improvement of the stability of a gene construct and its expression for a robust and complete interruption of pathogen transmission and the devise of safe means of spreading foreign antipathogen genes through mosquito populations in the wild. The implementation obstacles to overcome include proper risk assessment and management, conduct of studies to ensure safety for humans and the environment, devise of appropriate control strategies based on sound gene-driving systems, address properly ethical, legal and social implications of the release of GMM and public concerns. Although the development of GMM as disease-control tool is technically feasible, for proper implementation no field release must be undertaken until clear scientific proof of safety for humans and the environment and efficacy is provided and ELSI concerns and public acceptance are properly addresse

    High correlation between Chagas' disease serology and PCR-based detection of Trypanosoma cruzi kinetoplast DNA in bolivian children living in an endemic area

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    Submitted by sandra infurna ([email protected]) on 2016-06-29T15:31:55Z No. of bitstreams: 1 carlos20_morel_etal_IOC_1994.pdf: 578671 bytes, checksum: 49c1bfe1a3334487aede673ca532654a (MD5)Approved for entry into archive by sandra infurna ([email protected]) on 2016-06-29T15:43:03Z (GMT) No. of bitstreams: 1 carlos20_morel_etal_IOC_1994.pdf: 578671 bytes, checksum: 49c1bfe1a3334487aede673ca532654a (MD5)Made available in DSpace on 2016-06-29T15:43:03Z (GMT). No. of bitstreams: 1 carlos20_morel_etal_IOC_1994.pdf: 578671 bytes, checksum: 49c1bfe1a3334487aede673ca532654a (MD5) Previous issue date: 1994Submitted by Angelo Silva ([email protected]) on 2016-07-07T11:16:53Z No. of bitstreams: 3 carlos20_morel_etal_IOC_1994.pdf.txt: 19093 bytes, checksum: d5ec7ae508e9468c358833ecf7cf1076 (MD5) carlos20_morel_etal_IOC_1994.pdf: 578671 bytes, checksum: 49c1bfe1a3334487aede673ca532654a (MD5) license.txt: 2991 bytes, checksum: 5a560609d32a3863062d77ff32785d58 (MD5)Approved for entry into archive by sandra infurna ([email protected]) on 2016-07-07T12:13:56Z (GMT) No. of bitstreams: 3 license.txt: 2991 bytes, checksum: 5a560609d32a3863062d77ff32785d58 (MD5) carlos20_morel_etal_IOC_1994.pdf: 578671 bytes, checksum: 49c1bfe1a3334487aede673ca532654a (MD5) carlos20_morel_etal_IOC_1994.pdf.txt: 19093 bytes, checksum: d5ec7ae508e9468c358833ecf7cf1076 (MD5)Made available in DSpace on 2016-07-07T12:13:56Z (GMT). No. of bitstreams: 3 license.txt: 2991 bytes, checksum: 5a560609d32a3863062d77ff32785d58 (MD5) carlos20_morel_etal_IOC_1994.pdf: 578671 bytes, checksum: 49c1bfe1a3334487aede673ca532654a (MD5) carlos20_morel_etal_IOC_1994.pdf.txt: 19093 bytes, checksum: d5ec7ae508e9468c358833ecf7cf1076 (MD5) Previous issue date: 1994Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de Bioquímica e Biologia Molecular. Laboratório de Biologia Molecular e Doenças Endêmicas. Rio de Janeiro, RJ, Brasil.UMR CNRS/ ORSTOM, Génétique Moléculaire des Parasites et des Vecteurs. CP 9214, La Paz, Bolivia.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de Bioquímica e Biologia Molecular. Laboratório de Biologia Molecular e Doenças Endêmicas. Rio de Janeiro, RJ, Brasil.Universidad Mayor de San Andres. Instituto Boliviano de Biologia de Altura. La Paz, Bolivia.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de Bioquímica e Biologia Molecular. Laboratório de Biologia Molecular e Doenças Endêmicas. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de Bioquímica e Biologia Molecular. Laboratório de Biologia Molecular e Doenças Endêmicas. Rio de Janeiro, RJ, Brasil.UMR CNRS/ ORSTOM, Génétique Moléculaire des Parasites et des Vecteurs. CP 9214, La Paz, Bolivia.The detection of Tr)tpunosomu crirzi kinetoplast DNA by polymerase chain reaction (PCR) amplification is a potentially powerful tool for the parasitological diagnosis of Chagas’ disease. We have applied this technique in a field situation in Bolivia, where 45 children from a primary school were subjected to serological testing, buffy coat analysis and PCR diagnosis. 26 of the 28 serology-positive individuals were also positive by PCR. In addition, two serology-negative children gave a positive result by PCR, including one who was positive in the buffy coat test. These results suggest that PCR detection of T. cruzi DNA in blood can be a very useful complement to serology in Chagas’ disease diagnosis in Bolivia

    Renormalization Group Approach to the Coulomb Pseudopotential for C_{60}

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    A numerical renormalization group technique recently developed by one of us is used to analyse the Coulomb pseudopotential (μ{\mu^*}) in C60{{\rm C}_{60}} for a variety of bare potentials. We find a large reduction in μ{\mu^*} due to intraball screening alone, leading to an interesting non-monotonic dependence of μ{\mu^*} on the bare interaction strength. We find that μ{\mu^*} is positive for physically reasonable bare parameters, but small enough to make the electron-phonon coupling a viable mechanism for superconductivity in alkali-doped fullerides. We end with some open problems.Comment: 12 pages, latex, 7 figures available from [email protected]

    The 3-Band Hubbard-Model versus the 1-Band Model for the high-Tc Cuprates: Pairing Dynamics, Superconductivity and the Ground-State Phase Diagram

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    One central challenge in high-TcT_c superconductivity (SC) is to derive a detailed understanding for the specific role of the CuCu-dx2y2d_{x^2-y^2} and OO-px,yp_{x,y} orbital degrees of freedom. In most theoretical studies an effective one-band Hubbard (1BH) or t-J model has been used. Here, the physics is that of doping into a Mott-insulator, whereas the actual high-TcT_c cuprates are doped charge-transfer insulators. To shed light on the related question, where the material-dependent physics enters, we compare the competing magnetic and superconducting phases in the ground state, the single- and two-particle excitations and, in particular, the pairing interaction and its dynamics in the three-band Hubbard (3BH) and 1BH-models. Using a cluster embedding scheme, i.e. the variational cluster approach (VCA), we find which frequencies are relevant for pairing in the two models as a function of interaction strength and doping: in the 3BH-models the interaction in the low- to optimal-doping regime is dominated by retarded pairing due to low-energy spin fluctuations with surprisingly little influence of inter-band (p-d charge) fluctuations. On the other hand, in the 1BH-model, in addition a part comes from "high-energy" excited states (Hubbard band), which may be identified with a non-retarded contribution. We find these differences between a charge-transfer and a Mott insulator to be renormalized away for the ground-state phase diagram of the 3BH- and 1BH-models, which are in close overall agreement, i.e. are "universal". On the other hand, we expect the differences - and thus, the material dependence to show up in the "non-universal" finite-T phase diagram (TcT_c-values).Comment: 17 pages, 9 figure

    PCR-based diagnosis for Chagas' disease in bolivian children living in an active transmission area : comparison with conventional serological and parasitological diagnosis

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    A large field study has been performed in the Cochabamba region of Bolivia with the aim of comparing the polymerase chain reaction (PCR) with other diagnosis methods for Chagas' disease. The amplification of #Trypanosoma cruzi$-specific kinetoplast DNA sequences in blood samples was compared with classical serological methods, specific IgM detection and direct parasite visualization for 268 school children in a single village where Chagas' disease transmission is active. Of 113 children positive by classical serology or buffy coat examination, 106 were detected by PCR (sensitivity : 93,8%). We did not observe any significant difference of PCR sensitivity between initial (IgM and/or buffy coat positive) and indeterminate stage (only IgG positive) patients. Among the remaining 155 children unconfirmed as chagasic (who were either only IgM positive, or IgG-, IgM-, and buffy coat -negative) only one case was PCR positive. This case may be due to DNA contamination, or to a very recent infection not detected otherwise, or to specific immune depression. These results show that PCR is a very sensitive parasitological test for Chagas' disease in active transmission regions. The future follow-up of the possibly infected patients who were only IgM-positive should clarify the interest of PCR and IgM tests in the detection of starting infections. (Résumé d'auteur

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

    Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

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    Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

    Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

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    This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio

    Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

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    The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter

    Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

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    We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters
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