Now showing items 10-29 of 49

    • 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 ...
    • 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)
    • 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 ...
    • (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 ...
    • Phototransport Properties of a-SiC:H Alloys 

      Balberg, I.; Nery, Guillermo; Ramírez Porras, Arturo; Resto, O.; Weisz, S. Z.; Lubianiker, Y. (1995)
      We report a study of the mobility-lifetime products of the two charge carriers in a-SiC:H alloys. The measurements were carried out as a function of the carbon concentration and the temperature. An analysis, relying on the ...