340 research outputs found

    Electronic transport through a parallel--coupled triple quantum dot molecule: Fano resonances and bound states in the continuum

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    The electronic transport through a triple quantum dot molecule attached in parallel to leads in presence of a magnetic flux is studied. Analytical expressions of the linear conductance and density of states for the molecule in equilibrium at zero temperature are obtained. As a consequence of quantum interference, the conductance exhibits in general a Breit--Wigner and two Fano resonances, the positions and widths of which are controlled by the magnetic field. Every two flux quanta, there is an inversion of roles of the bonding and antibonding states. For particular values of the magnetic flux and dot-lead couplings, one or even both Fano resonances collapse and bound states in the continuum (BIC's) are formed. The line broadenings of the molecular states are examined as a function of the Aharonov--Bohm phase around the condition for the formation of BIC's, finding resonances extremely narrow and robust against variations of the magnetic field.Comment: 15 pages, 7 figure

    Sustitución de bombeos aspirando de depósitos de rotura de carga por bombeos con aspiración directa de red. El caso de la estación de bombeo de Adsubia-Cabanes (Jávea)

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    [ES] En sistemas de distribución de agua urbanos, en los puntos donde la presión es insuficiente para abastecer adecuadamente una parte de la red, se instalan estaciones de bombeo que refuerzan la presión solamente en esta parte del sistema. Es el caso, por una parte, de los grupos hidropresores instalados en edificios altos, mediante los cuales se puede suministrar sin problemas a partir de aproximadamente el tercero o cuarto piso. Y por otra parte están las estaciones de bombeo que impulsan el agua de la red hacia sectores con cota elevada, los cuales no pueden ser suministrados directamente desde el o los puntos de cabecera del sistema. Tanto en unos casos como en otros la aspiración de los grupos de bombeo se puede realizar desde depósitos a presión atmosférica, los cuales se alimentan del agua de la red (depósitos de rotura de carga), o bien aspirando directamente de la propia red. En el caso del bombeo desde depósitos de rotura de carga el agua de alimentación de los grupos de bombeo se despresuriza al entrar al depósito, perdiendo la energía de presión de la que dispone en el interior de la red (Cobacho et al., 2012). En este caso los transitorios de puesta en marcha o parada de los grupos de bombeo no afectan al sistema de distribución. En el caso de aspiración directa de red se aprovecha la energía de presión del agua aspirada, con lo cual la altura de bombeo y la energía consumida en la impulsión son menores. Esta es una razón importante que justifica la adopción de esta solución, máxime con el ahorro en potencia contratada y en consumo energético que se puede conseguir. Además, de esta manera se contribuye a la reducción de emisiones de gases de efecto invernadero que supone el ahorro en consumo energético (Basupi et al., 2014). Pero en contra de esta solución actúa el hecho de que los transitorios originados por las maniobras de los grupos de bombeo pueden llegar a afectar a la red (Davis, 210; Soriano et al., 2014), lo que obliga en instalaciones de importancia a disponer de adecuados sistemas de protección contra transitorios hidráulicos. En este sentido, la presente comunicación trata sobre la sustitución de los grupos de la estación de bombeo de Adsubia-Cabanes, la cual ha estado aspirando de un depósito de rotura de carga alimentado desde la red de distribución de agua potable de Jávea, por nuevos grupos de bombeo con aspiración directa de red. Se definen además los sistemas de protección contra transitorios hidráulicos a instalar tanto en la parte de aspiración como en la de impulsión de la estación de bombeo modificada, en los cuales se combinan calderines con válvulas de protección. Para llevar a cabo el estudio se utiliza el programa Allievi para cálculo y simulación de transitorios hidráulicos.Espert Alemany, VB.; Henarejos Cardona, J.; Cabrera Marcet, E.; Ladrón De Guevara Diego, P. (2015). Sustitución de bombeos aspirando de depósitos de rotura de carga por bombeos con aspiración directa de red. El caso de la estación de bombeo de Adsubia-Cabanes (Jávea). Universidad de Córdoba. 1005-1014. http://hdl.handle.net/10251/141657S1005101

    Simulation Study of Chic -> J/Psi + gamma Detection with J/Psi -> e+ e- in pp Collisions

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    We present Monte Carlo preliminary results about the feasibility to detect the Chic family in p-p collisions at 14 TeV in the ALICE Central Barrel at CERN LHC. The Chic1 and Chic2 were forced to decay in the channel J/Psi + gamma -> e+ e- + gamma and were merged with a proton-proton non-biased collision. After MonteCarlo transport and simulation of the detector response, the e+, e- and converted gamma were reconstructed and identified in the ALICE ITS, TPC and TRD detectors. Separate signals corresponding to gamma from Chic1 and from Chic2 were observed. The position and relative weight of the fit to gaussians agreed with the input values within the statistical limits. Similar studies will be done for Pb-Pb collisions

    A detailed analysis of the Gl 486 planetary system

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    Context. The Gl 486 system consists of a very nearby, relatively bright, weakly active M3.5 V star at just 8 pc with a warm transiting rocky planet of about 1.3 R-circle plus and 3.0 M-circle plus. It is ideal for both transmission and emission spectroscopy and for testing interior models of telluric planets. Aims. To prepare for future studies, we aim to thoroughly characterise the planetary system with new accurate and precise data collected with state-of-the-art photometers from space and spectrometers and interferometers from the ground. Methods. We collected light curves of seven new transits observed with the CHEOPS space mission and new radial velocities obtained with MAROON-X at the 8.1 m Gemini North telescope and CARMENES at the 3.5 m Calar Alto telescope, together with previously published spectroscopic and photometric data from the two spectrographs and TESS. We also performed near-infrared interferometric observations with the CHARA Array and new photometric monitoring with a suite of smaller telescopes (AstroLAB, LCOGT, OSN, TJO). This extraordinary and rich data set was the input for our comprehensive analysis. Results. From interferometry, we measure a limb-darkened disc angular size of the star Gl 486 at theta(LDD) = 0.390 +/- 0.018 mas. Together with a corrected Gaia EDR3 parallax, we obtain a stellar radius R-* = 0.339 +/- 0.015 R-circle plus. We also measure a stellar rotation period at P-rot = 49.9 +/- 5.5 days, an upper limit to its XUV (5-920 A) flux informed by new Hubble/STIS data, and, for the first time, a variety of element abundances (Fe, Mg, Si, V, Sr, Zr, Rb) and C/O ratio. Moreover, we imposed restrictive constraints on the presence of additional components, either stellar or sub-stellar, in the system. With the input stellar parameters and the radial-velocity and transit data, we determine the radius and mass of the planet Gl 486 b at R-p = 1.343(-0.062)(+0.063) R-circle plus and M-p = 3.00(-0.12)(+0.13) M-circle plus, with relative uncertainties of the planet radius and mass of 4.7% and 4.2%, respectively. From the planet parameters and the stellar element abundances, we infer the most probable models of planet internal structure and composition, which are consistent with a relatively small metallic core with respect to the Earth, a deep silicate mantle, and a thin volatile upper layer. With all these ingredients, we outline prospects for Gl 486 b atmospheric studies, especially with forthcoming James Webb Space Telescope (Webb) observations.The David & Lucile Packard FoundationHeising-Simons FoundationGemini ObservatoryUniversity of ChicagoMax Planck SocietyConsejo Superior de Investigaciones Cientificas (CSIC)Spanish GovernmentEuropean Commission FICTS-2011-02 ICTS-2017-07-CAHA-4 CAHA16-CE-3978German Research Foundation (DFG) FOR2544National Science Foundation (NSF) AST-1636624 AST-2034336 2108465 DGE 1746045European Research Council (ERC) 639889National Aeronautics & Space Administration (NASA) XRP NNX16AD43GNational Science Foundation (NSF) AST 1909165Wise Observatory, Tel-Aviv University, Israel TAU2021A-015Agencia Estatal de Investigacion of the Ministerio de Ciencia, Innovacion y Universidades and the ERDF PID2019-109522GB-C5[1:4] PID2019-107061GBC64 PID2019-110689RB-100 PGC2018-095317-B-C21 PGC2018-102108-BI00Centre of Excellence "Severo Ochoa" CEX2019-000920-SCentre of Excellence "Maria de Maeztu" CEX2019-000920-SInstituto de Astrofisica de Andalucia SEV-2017-0709Centro de Astrobiologia MDM2017-0737German Research Foundation (DFG)European Commission FOR2544 (KU 3625/2-1)Germany's Excellence Strategy to the Excellence Cluster ORIGINS EXC-2094 -390783311European Research Council (ERC)European Commission 639889Bulgarian National Science Fund through VIHREN-2021 KP-06-DB/5Schweizerischer Nationalfonds zur Forderung der wissenschaftlichen Forschung/Fonds national suisse de la recherche scientifique PZ00P2_174028United Kingdom Science Technology and Facilities Council 630008203Princeton UniversityUniversidad La Laguna through the Margarita Salas Fellowship from the Spanish Ministerio de UniversidadesEU Next Generation funds UNI/551/2021Generalitat de Catalunya (CERCA programme

    Transport through a quantum wire with a side quantum-dot array

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    A noninteracting quantum-dot array side-coupled to a quantum wire is studied. Transport through the quantum wire is investigated by using a noninteracting Anderson tunneling Hamiltonian. The conductance at zero temperature develops an oscillating band with resonances and antiresonances due to constructive and destructive interference in the ballistic channel, respectively. Moreover, we have found an odd-even parity in the system, whose conductance vanishes for an odd number of quantum dots while becomes 2e2/h2e^2/h for an even number. We established an explicit relation between this odd-even parity, and the positions of the resonances and antiresonances of the conductivity with the spectrum of the isolated QD arrayComment: 5 pages, 4 figures, submitted to PR

    Conductance and persistent current of a quantum ring coupled to a quantum wire under external fields

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    The electronic transport of a noninteracting quantum ring side-coupled to a quantum wire is studied via a single-band tunneling tight-binding Hamiltonian. We found that the system develops an oscillating band with antiresonances and resonances arising from the hybridization of the quasibound levels of the ring and the coupling to the quantum wire. The positions of the antiresonances correspond exactly to the electronic spectrum of the isolated ring. Moreover, for a uniform quantum ring the conductance and the persistent current density were found to exhibit a particular odd-even parity related with the ring-order. The effects of an in-plane electric field was also studied. This field shifts the electronic spectrum and damps the amplitude of the persistent current density. These features may be used to control externally the energy spectra and the amplitude of the persistent current.Comment: Revised version, 7 pages and 9 figures. To appear in Phys. Rev.

    Towards an integrated crowdsourcing definition

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    Crowdsourcing is a relatively recent concept that encompasses many practices. This diversity leads to the blurring of the limits of crowdsourcing that may be identified virtually with any type of internet-based collaborative activity, such as co-creation or user innovation. Varying definitions of crowdsourcing exist, and therefore some authors present certain specific examples of crowdsourcing as paradigmatic, while others present the same examples as the opposite. In this article, existing definitions of crowdsourcing are analysed to extract common elements and to establish the basic characteristics of any crowdsourcing initiative. Based on these existing definitions, an exhaustive and consistent definition for crowdsourcing is presented and contrasted in 11 cases.Estelles Arolas, E.; González-Ladrón-De-Guevara, F. (2012). Towards an integrated crowdsourcing definition. Journal of Information Science. 32(2):189-200. doi:10.1177/0165551512437638S189200322Vukovic, M., & Bartolini, C. (2010). Towards a Research Agenda for Enterprise Crowdsourcing. Leveraging Applications of Formal Methods, Verification, and Validation, 425-434. doi:10.1007/978-3-642-16558-0_36Brabham, D. C. (2008). Crowdsourcing as a Model for Problem Solving. Convergence: The International Journal of Research into New Media Technologies, 14(1), 75-90. doi:10.1177/1354856507084420Vukovic, M. (2009). Crowdsourcing for Enterprises. 2009 Congress on Services - I. doi:10.1109/services-i.2009.56Doan, A., Ramakrishnan, R., & Halevy, A. Y. (2011). Crowdsourcing systems on the World-Wide Web. Communications of the ACM, 54(4), 86. doi:10.1145/1924421.1924442Brabham, D. C. (2008). Moving the crowd at iStockphoto: The composition of the crowd and motivations for participation in a crowdsourcing application. First Monday, 13(6). doi:10.5210/fm.v13i6.2159Huberman, B. A., Romero, D. M., & Wu, F. (2009). Crowdsourcing, attention and productivity. Journal of Information Science, 35(6), 758-765. doi:10.1177/0165551509346786Andriole, S. J. (2010). Business impact of Web 2.0 technologies. Communications of the ACM, 53(12), 67. doi:10.1145/1859204.1859225Denyer, D., Tranfield, D., & van Aken, J. E. (2008). Developing Design Propositions through Research Synthesis. Organization Studies, 29(3), 393-413. doi:10.1177/0170840607088020Egger, M., Smith, G. D., & Altman, D. G. (Eds.). (2001). Systematic Reviews in Health Care. doi:10.1002/9780470693926Tatarkiewicz, W. (1980). A History of Six Ideas. doi:10.1007/978-94-009-8805-7Cosma, G., & Joy, M. (2008). Towards a Definition of Source-Code Plagiarism. IEEE Transactions on Education, 51(2), 195-200. doi:10.1109/te.2007.906776Brabham, D. C. (2009). Crowdsourcing the Public Participation Process for Planning Projects. Planning Theory, 8(3), 242-262. doi:10.1177/1473095209104824Alonso, O., & Lease, M. (2011). Crowdsourcing 101. Proceedings of the fourth ACM international conference on Web search and data mining - WSDM ’11. doi:10.1145/1935826.1935831Bederson, B. B., & Quinn, A. J. (2011). Web workers unite! addressing challenges of online laborers. Proceedings of the 2011 annual conference extended abstracts on Human factors in computing systems - CHI EA ’11. doi:10.1145/1979742.1979606Grier, D. A. (2011). Not for All Markets. Computer, 44(5), 6-8. doi:10.1109/mc.2011.155Heer, J., & Bostock, M. (2010). Crowdsourcing graphical perception. Proceedings of the 28th international conference on Human factors in computing systems - CHI ’10. doi:10.1145/1753326.1753357Heymann, P., & Garcia-Molina, H. (2011). Turkalytics. Proceedings of the 20th international conference on World wide web - WWW ’11. doi:10.1145/1963405.1963473Kazai, G. (2011). In Search of Quality in Crowdsourcing for Search Engine Evaluation. Advances in Information Retrieval, 165-176. doi:10.1007/978-3-642-20161-5_17La Vecchia, G., & Cisternino, A. (2010). Collaborative Workforce, Business Process Crowdsourcing as an Alternative of BPO. Lecture Notes in Computer Science, 425-430. doi:10.1007/978-3-642-16985-4_40Liu, E., & Porter, T. (2010). Culture and KM in China. VINE, 40(3/4), 326-333. doi:10.1108/03055721011071449Oliveira, F., Ramos, I., & Santos, L. (2010). Definition of a Crowdsourcing Innovation Service for the European SMEs. Lecture Notes in Computer Science, 412-416. doi:10.1007/978-3-642-16985-4_37Porta, M., House, B., Buckley, L., & Blitz, A. (2008). Value 2.0: eight new rules for creating and capturing value from innovative technologies. Strategy & Leadership, 36(4), 10-18. doi:10.1108/10878570810888713Ribiere, V. M., & Tuggle, F. D. (Doug). (2010). Fostering innovation with KM 2.0. VINE, 40(1), 90-101. doi:10.1108/03055721011024955Sloane, P. (2011). The brave new world of open innovation. Strategic Direction, 27(5), 3-4. doi:10.1108/02580541111125725Wexler, M. N. (2011). Reconfiguring the sociology of the crowd: exploring crowdsourcing. International Journal of Sociology and Social Policy, 31(1/2), 6-20. doi:10.1108/01443331111104779Whitla, P. (2009). Crowdsourcing and Its Application in Marketing Activities. Contemporary Management Research, 5(1). doi:10.7903/cmr.1145Yang, J., Adamic, L. A., & Ackerman, M. S. (2008). Crowdsourcing and knowledge sharing. Proceedings of the 9th ACM conference on Electronic commerce - EC ’08. doi:10.1145/1386790.1386829Brabham, D. C. (2010). MOVING THE CROWD AT THREADLESS. Information, Communication & Society, 13(8), 1122-1145. doi:10.1080/13691181003624090Giudice, K. D. (2010). Crowdsourcing credibility: The impact of audience feedback on Web page credibility. Proceedings of the American Society for Information Science and Technology, 47(1), 1-9. doi:10.1002/meet.14504701099Stewart, O., Huerta, J. M., & Sader, M. (2009). Designing crowdsourcing community for the enterprise. Proceedings of the ACM SIGKDD Workshop on Human Computation - HCOMP ’09. doi:10.1145/1600150.1600168Maslow, A. H. (1943). A theory of human motivation. Psychological Review, 50(4), 370-396. doi:10.1037/h0054346Veal, A. J. (Ed.). (2002). Leisure and tourism policy and planning. doi:10.1079/9780851995465.0000Dahlander, L., & Gann, D. M. (2010). How open is innovation? Research Policy, 39(6), 699-709. doi:10.1016/j.respol.2010.01.01

    Measurement of negative particle multiplicity in S - Pb collisions at 200 GeV/c per nucleon with the NA36 TPC

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    A high statistics study of the negative multiplicity distribution from S-Pb collisions at 200 GeV/c per nucleon is presented. The NA36 TPC was used to detect charged particles; corrections are based upon the maximum entropy method.A high statistics study of the negative multiplicity distribution from S-Pb collisions at 200 GeV/c per nucleon is presented. The NA36 TPC was used to detect charged particles; corrections are based upon the maximum entropy method.A high statistics study of the negative particle multiplicity distribution from S–Pb collisions at 200 GeV/ c per nucleon is presented. The NA36 TPC was used to detect charged particles; corrections are based upon the maximum entropy method
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