Now showing items 49-62 of 62

    • Stochastic approach to the smart quantum confinement model in porous silicon 

      Ramírez Porras, Arturo; Weisz, S. Z. (Surface Science 515 (2002) L509-L513, 2002)
      A model that encompasses two approaches to explain the photoluminescence in p-type porous silicon is proposed. The model considers a stochastic distribution of nanocrystallite sizes within the porous matrix and explain the ...
    • Structure factor of a relaxor ferroelectric 

      Guzmán Verri, Gian Giacomo; Varma, Chandra M. (2015-04-14)
      We study a minimal model for a relaxor ferroelectric including dipolar interactions, and short-range harmonic and anharmonic forces for the critical modes as in the theory of pure ferroelectrics together with quenched ...
    • Study of oxide bands in p-type porous silicon layers 

      Rojas Fernández, Yoselin; Hernández López, María José; Ramírez Porras, Arturo (2019)
      The interest in developing fast and reliable chemical and biochemical sensors in an inexpensive way is something that has attracted a lot of efforts in the last decades. One of the potential material candidates is ...
    • The 2:3:6 quasi-periodic oscillation structure in GRS 1915+105 and cubic subharmonics in the context of relativistic discoseismology 

      Ortega Rodríguez, Manuel; Solís Sánchez, Hugo; López Barquero, Vanessa; Matamoros Alvarado, Bryan; Venegas Li, Ariadna (Monthly Notices of the Royal Astronomical Society 440:3011-3015, 2014-06-01)
      We propose a simple toy model to explain the 2:3:6 quasi-periodic oscillation (QPO) structure in GRS 1915+105 and, more generally, the 2:3 QPO structure in XTE J1550−564, GRO J1655−40 and H1743−322. The model exploits the ...
    • The early rainy season in Central America: the role of thetropical North Atlantic SSTs 

      Maldonado Mora, Tito José; Alfaro Martínez, Eric J.; Rutgersson, Anna; Amador Astúa, Jorge Alberto (2016)
      We explored the relationship between the precipitation anomalies during May to June as the first peak of the rainy season in the Pacific slope of Central America, and sea surface temperature (SST) fluctuations in the ...
    • The gigaelectronvolt counterpart of ver j2019+407 in the northern shell of the supernova remnant g78.2+2.1 (γ cygni) 

      Fraija Cabrera, Nissim Illich; Araya Arguedas, Miguel (2016-07)
      Analysis of gamma-ray emission from the supernova remnant G78.2+2.1 (γ Cygni) with 7.2 years of cumulative data from the Fermi Large Area Telescope shows a distinct hard, bright, and extended component to the north of the ...
    • The Hubble Constant and the Deceleration Parameter in Anisotropic Cosmological Spaces of Petrov type D 

      Alvarado Marín, Rodrigo Eduardo (2016-11)
      In this paper the Hubble parameter and the deceleration parameter are analyzed for a group of anisotropic homogeneous solutions of the Petrov type-D. It is obtained that for the said set of solutions can be constructed a ...
    • The mechanical career of Councillor Orffyreus, confidence man 

      Jenkins Villalobos, Alejandro (2013-05)
      In the early 18th century, J. E. E. Bessler, known as Orffyreus, constructed several wheels that he claimed could keep turning forever, powered only by gravity. He never revealed the details of his invention, but he ...
    • Tropical precipitation anomalies and d‐excess evolution during El Niño 2014‐16 

      Sánchez Murillo, Ricardo; Durán Quesada, Ana María; Birkel Dostal, Christian; Esquivel Hernández, Germain; Boll, Jan (2016)
      The last 2014-16 El Niño event was among the three strongest episodes on record. El Niño considerably changes annual and seasonal precipitation across the tropics. Here, we present a unique stable isotope data set of daily ...
    • Tsunamis and Tsunami Hazards in Central America 

      Fernández Arce, Mario; Molina, Enrique; Havskov, Jens; Kuvvet, Atakan (2000-02)
      A tsunami catalogue for Central America is compiled containing 49 tsunamis for the period 1539–1996, thirty seven of them are in the Pacific and twelve in the Caribbean. At the Caribbean side, 5 events are related with ...
    • Tsunamis and tsunami prepardness in Costa Rica, Central America 

      Fernández Arce, Mario; Alvarado Delgado, Guillermo (2005-12)
      Pacific and Atlantic sides of Costa Rica there are coastal segments characterised by a flat relief, which increases the vulnerability of the coastal communities. In addition to tsunamis originating in the Middle American ...
    • Vacuum treatment to stabilize oxidation at low temperature region in porous silicon 

      Allen, Kevin; Pereira Cubillo, Juan Sebastián; Ramírez Porras, Arturo (2020)
      Oxidation in porous silicon is studied for as-etched samples and samples subjected to high vacuum at room temperature. Attenuated Total Reflectance (ATR) measurements in infrared spectroscopy for temperatures ranging from ...
    • Verificación del Comisionamiento del Acelerador Lineal UNIQUE de Varian 

      Calvo Alfaro, Jorge Arturo (2021)
      Esta tesis trata sobre la Verificación del Comisionamiento del Acelerador Lineal UNIQUE, el cual se encuentra en el Hospital México. La metodología usada para este fin comprende el Protocolo Internacional para la Determinación ...
    • Why is the electrocaloric effect so small in ferroelectrics? 

      Guzmán Verri, Gian Giacomo; Littlewood, Peter B. (2016-05-19)
      Ferroelectrics are attractive candidate materials for environmentally friendly solid state refrigeration free of greenhouse gases. Their thermal response upon variations of external electric fields is largest in the vicinity ...