Browsing by Author "Roman, Javier"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Actitudes disruptivas en el ambiente de pabellón
    (Elsevier, 2017) Campos Daziano, Mauricio Andrés; Lira Salas, María Jesús; Mery Illanes, Pamela Pía; Pimentel Muller, Fernando Ernesto; Zuñiga Parada, Denisse Alejandra; Roman, Javier
  • No Thumbnail Available
    Item
    Effect of Chloride Ions on the Corrosion of Galvanized Steel Embedded in Concrete Prepared with Cements of Different Composition
    (2014) Roman, Javier; Vera, Rosa; Bagnara, Margarita; Carvajal, Ana M.; Aperador, William
    The behavior of galvanized steel inside concrete prepared with different types of cement is of vital importance in the latest construction mega-projects, which demand durability in environments as aggressive as sea water. This paper presents the results of a year of study on the behavior of galvanized steel rebars against the action of chloride ions. The steel bars in question were used in reinforced concrete prepared with Standard Portland cement and Pozzolanic cement at a water/cement ratio of 0.45, and then exposed to a 2.6 M NaCl solution with cycles of 4 days semi-immersion and 3 days drying at 60 degrees C. The state of the galvanized steel bars was monitored through measurement of corrosion potential and corrosion current over time. Chloride ion entry profiles were also studied. The composition and morphology of the corrosion products formed on the galvanized steel were analyzed by MEB-EDAX. Polarization curves were used to evaluate the behavior of the galvanized steel bars in alkaline solutions; these bars were taken from concrete specimens exposed to an artificial marine media. It was shown that the behavior of the galvanized steel bars varies with the composition of the cement used depending on tricalcium aluminate content and its interaction with the chloride ions. In both types of concrete the galvanized steel bar was found to be in a passive state at the end of the test period.
  • No Thumbnail Available
    Item
    Intraoperative immediate strength recovery following lacertus fibrosus release in patients with proximal median nerve compression at the elbow
    (2023) Azocar, Camila; Corvalan, Gonzalo; Orellana, Pablo; Cobb, Peter; Liendo, Rodrigo; Roman, Javier
    PurposeIn the literature, we find that patients with lacertus syndrome (LS), proximal median nerve compression at the elbow, present subjective improvement of thumb, and index flexion strength after lacertus fibrosus (LF) release. The aim of this study is to objectively evaluate the immediate change in intraoperative flexion strength after LF release.MethodWe retrospectively reviewed prospectively collected data of a cohort of 24 patients with a double crush syndrome of the median nerve with no response to conservative treatment. All patients had surgery with LF and carpal tunnel release (CTR) under wide-awake local anaesthesia and no tourniquet (WALANT) and were evaluated intraoperatively with a dynamometer immediately before and after LF release. Flexor digitorum profundus of the second finger (FDP2) and Flexor pollicis longus (FPL) were tested in peak strength to failure. The primary outcome was the percentage of change in strength before and after the release in both assessed muscles. CTR was done after evaluating the change in flexor strength.ResultsA percentage of 79.2 women with an average age of 43.3 years. The average strength of FDP2 before LF release was 15.5 pounds (lbs.) (7.0 kg) (SD, 7.2 lbs (3.3 kg)) and 27.1 lbs. (12.2 kg) (SD, 7.1 lbs. (3.2 kg)) after LF release, which corresponds to a 96% (SD, 70%) change in strength (p=0.000). For FPL, the average pre-release strength was 17.7 lbs. (8.0kg) (SD, 4.8 lbs. (2.2 kg)) and 27.4 lbs. (12.4 kg) (SD, 5.2 lbs. (2.4 kg)) post-release, this corresponded to a 65% (SD, 38%) change in strength (p=0.000).ConclusionsPeak strength to failure in FDP2 and FPL has an immediate significant recovery after LF surgical release in patients with Lacertus syndrome.Level of evidence: IV, retrospective study.
  • No Thumbnail Available
    Item
    The CAVITY project: The spatially resolved stellar population properties of galaxies in voids
    (2024) Conrado, Ana M.; Delgado, Rosa M. Gonzalez; Garcia-Benito, Ruben; Perez, Isabel; Verley, Simon; Ruiz-Lara, Tomas; Sanchez-Menguiano, Laura; Puertas, Salvador Duarte; Jimenez, Andoni; Dominguez-Gomez, Jesus; Espada, Daniel; Argudo-Fernandez, Maria; Alcazar-Laynez, Manuel; Blazquez-Calero, Guillermo; Bidaran, Bahar; Zurita, Almudena; Peletier, Reynier; Torres-Rios, Gloria; Florido, Estrella; Rodriguez Martinez, Monica; del Moral-Castro, Ignacio; van de Weygaert, Rien; Falcon-Barroso, Jesus; Lugo-Aranda, Alejandra Z.; Sanchez, Sebastian F.; van der Hulst, Thijs; Courtois, Helene M.; Ferre-Mateu, Anna; Sanchez-Blazquez, Patricia; Roman, Javier; Aceituno, Jesus
    The Universe is shaped as a web-like structure, formed by clusters, filaments, and walls that leave large low number-density volumes in between named voids. Galaxies in voids have been found to be of a later type, bluer, less massive, and to have a slower evolution than galaxies in denser environments (filaments and walls). However, the effect of the void environment on their stellar population properties is still unclear. We aim to address this question using 118 optical integral field unit datacubes from the Calar Alto Void Integral-field Treasury surveY (CAVITY), observed with the PMAS/PPaK spectrograph at the 3.5 m telescope at the Calar Alto Observatory (Almer & iacute;a, Spain). We fitted their spectra from 3750 & Aring; to 7000 & Aring; with the non-parametric full spectral fitting code STARLIGHT to estimate their stellar population properties: stellar mass, stellar mass surface density, age, star formation rate (SFR), and specific star formation rate (sSFR). We analysed the results through the global properties, assessing the behaviour of the whole galaxy, and the spatially resolved information, by obtaining the radial profiles from the 2D maps up to the 2 half-light radius of each stellar population property. The results were examined with respect to their morphological type and stellar mass. Then, we compared them with a control sample of galaxies in filaments and walls, selected from the CALIFA survey and analysed following the same procedure. To make a fair comparison between the samples, we selected a twin filament galaxy for each void galaxy of the same morphological type and closest stellar mass, to match the void galaxy sample as much as possible in morphology and mass. Key findings from our global and spatially resolved analysis include void galaxies having a slightly higher half-light radius (HLR), lower stellar mass surface density, and younger ages across all morphological types, and slightly elevated SFR and sSFR (only significant enough for Sas). Many of these differences appear in the outer parts of spiral galaxies (HLR > 1), where discs are younger and exhibit a higher sSFR compared to galaxies in filaments and walls, indicative of less evolved discs. This trend is also found for early-type spirals, suggesting a slower transition from star-forming to quiescent states in voids. Our analysis indicates that void galaxies, influenced by their surroundings, undergo a more gradual evolution, especially in their outer regions, with a more pronounced effect for low-mass galaxies. We find that below a certain mass threshold, environmental processes play a more influential role in galactic evolution.