Now showing items 10-29 of 51

    • Design and Characterization of a High Vacuum Metals Deposition System based on Electron Beam Evaporation 

      Ramírez Porras, Arturo; Avendaño Soto, Esteban Damián; Araya Pochet, José (2010-08-03)
      We describe a high vacuum metals deposition system based ona variation of a pendant-drop type electron beam evaporator.This system uses a Molybdenum crucible as an evaporantinstead of a rod or wire usually used in ultrathin ...
    • Diseño y caracterización de un enfriador de átomos de tipo “desacelerador Zeeman” 

      Guevara Bertsch, Milena; Salfenmoser, Lena; Chavarría Sibaja, Andrés; Avendaño Soto, Esteban Damián; Herrera Sancho, Óscar Andrey (2016)
      Nosotros presentamos un método que utiliza simultáneamente dos modelos matemáticos, con el objetivo de optimizar el diseño de un desacelerador Zeeman, con miras a la implementación de átomos ultrafríos a la física del ...
    • Diseño y simulación de un maniquí para la cuantificación del desempeño de sondas intraoperatorias gamma 

      González López, Dagoberto Eloy (2020-05-28)
      La técnica de cirugía radioguiada se basa en la utilización de una sonda detectora de radiaciones para la localización y posterior extracción a través de procedimientos quirúrgicos del tejido enfermo, el cual acumula ...
    • Distribución espacial de impactos de eventos hidrometeorológicos en América Central 

      Pérez Briceño, Paula Marcela; Alfaro Martínez, Eric J.; Hidalgo León, Hugo G.; Jiménez, Francisco (2016)
      América Central está expuesta a la ocurrencia de eventos hidrometeorológicos a lo largo del año y los impactos que estos pueden provocar van a estar mayormente localizados en áreas donde las variables tanto naturales como ...
    • Do Magnetic Fields Destroy Black Hole Accretion Disk g-Modes? 

      Ortega Rodríguez, Manuel; Solís Sánchez, Hugo; Arguedas Leiva, José Agustín; Wagoner, Robert V.; Levine, Adam (2015-08-04)
      Diskoseismology, the theoretical study of normal-mode oscillations in geometrically thin, optically thick accretion disks, is a strong candidate for explaining some quasi-periodic oscillations in the power spectra of many ...
    • El inflatón complejo 

      Padilla Víquez, Gerardo José (1999)
    • Electronic structure of silicon-based nanostructures 

      Guzmán Verri, Gian Giacomo; Lew Yan Voon, Lok Chong (2007-08-30)
      We have developed a unifying tight-binding Hamiltonian that can account for the electronic properties of recently proposed Si-based nanostructures, namely, Si graphene-like sheets and Si nanotubes. We considered the sp3s∗ ...
    • Estimation of Silicon Nanocrystalline Sizes from Photoluminescence Measurements of RF Co-Sputtered Si/SiO2 Films 

      Ramírez Porras, Arturo; Fonseca, L. F.; Resto, O. (Materials Research Society Symposium Proceedings 737 (2003), 2003)
      A stochastic distribution of nanocrystalline sizes model is applied to fit photoluminescence (PL) spectra of luminescent Si nanocrystals in a Si/SiO2 matrix synthesized by RF co-sputtering on the top of quartz substrates. ...
    • Exact solution of an ekpyrotic fluid and a primordial magnetic field in an anisotropic cosmological space-time of Petrov D 

      Alvarado Marín, Rodrigo Eduardo (2017)
      This document obtained and analyzed an exact solution of an ekpyrotic fluid (P = 5/3 µ) and a primordial magnetic field, so that the latter does not induce currents or electric fields. It is determined that the main role, ...
    • Exact Solutions of a Chaplygin Gas in an Anisotropic Space-Time of Petrov D 

      Alvarado Marín, Rodrigo Eduardo (2017)
      This document obtains two exact solutions to the anisotropic spacetime of Petrov D by using the model of a perfect fluid. These solutions represent a scenario of a universe in which the pressure P and the energetic density ...
    • Fundamentals of silicene 

      Willatzen, Morten; Lew Yan Voon, Lok Chong; Guzmán Verri, Gian Giacomo (2017-08-02)
      Silicene is a single atomic layer of silicon (Si) much like graphene, the first example of an elemental twodimensional (2D) nanomaterial whose study led to the 2010 Nobel Prize in Physics. Until 2010 or so, the only known ...
    • (Hydro)climatological studies of climate change and variability in Central America 

      Hidalgo León, Hugo G. (2018-06-26)
      This is the presentation of Hugo Hidalgo at the CORDEX Central America and South America Training Workshop on Downscaling Techniques, in La Paz, Bolivia, June 25 to 27, 2018.
    • Interaction of a quantum field with a rotating heat bath 

      Alicki, Robert; Jenkins Villalobos, Alejandro (2018-08-01)
      The linear coupling of a rotating heat bath to a quantum field is studied in the framework of the Markovian master equation for the field's non-unitary time evolution. The bath's rotation induces population inversion for ...
    • Irreversibility in an ideal fluid 

      Jenkins Villalobos, Alejandro (2014-10)
      When a real fluid is expelled quickly from a tube, it forms a jet separated from the surrounding fluid by a thin, turbulent layer. On the other hand, when the same fluid is sucked into the tube, it comes in from all ...
    • Irreversibility of mechanical and hydrodynamic instabilities 

      Díaz Marín, Carlos D.; Jenkins Villalobos, Alejandro (2017-12-01)
      The literature on dynamical systems has, for the most part, considered self-oscillators (i.e., systems capable of generating and maintaining a periodic motion at the expense of an external energy source with no corresponding ...
    • Landau theory and giant room-temperature barocaloric effect 

      Corrales Salazar, A.; Brierley, Richard T.; Littlewood, Peter B.; Guzmán Verri, Gian Giacomo (2017-10-17)
      The structural phase transitions of MF3 (M = Al, Cr, V, Fe, Ti, Sc) metal trifluorides are studied within a simple Landau theory consisting of tilts of rigid MF6 octahedra associated with soft antiferrodistortive optic ...
    • Large isotropic negative thermal expansion above a structural quantum phase transition 

      Handunkanda, Sahan U.; Curry, Erin B.; Voronov, Vladimir; Said, Ayman H.; Guzmán Verri, Gian Giacomo; Brierley, Richard T.; Littlewood, Peter B.; Hancock, Jason N. (2015-10-01)
      Perovskite structured materials contain myriad tunable ordered phases of electronic and magnetic origin with proven technological importance and strong promise for a variety of energy solutions. An always-contributing ...
    • Negative Thermal Expansion in Open Perovskites near the Precipice of Structural Stability 

      Occhialini, Connor A.; Guzmán Verri, Gian Giacomo; Handunkanda, Sahan U.; Hancock, Jason N. (2018)
      Negative thermal expansion (NTE) describes the anomalous propensity of materials to shrink when heated. Since its discovery, the NTE effect has been found in a wide variety of materials with an array of magnetic, electronic ...
    • Negative thermal expansion near two structural quantum phase transitions Connor 

      Guzmán Verri, Gian Giacomo; Hancock, Jason N. (2017-12-18)
      Recent experimental work has revealed that the unusually strong, isotropic structural negative thermal expansion in cubic perovskite ionic insulator ScF3 occurs in excited states above a ground state tuned very near a ...
    • Observed Changes (1970-1999) in Extreme Hydroclimatic Events in Central America 

      Hidalgo León, Hugo G.; Alfaro Martínez, Eric J. (2018-04-20)
      Previous studies have shown that most of Central America has been experiencing warming trends during the last 30-50 years, while precipitation annual totals have not changed much. Warming alone can exacerbate the effects ...