264 research outputs found
Escuchar las viejas voces. Transformaciones y demandas de la Universidad de Chile
Vida y Problemas de la UniversidadSituaciĂłn y Perspectiva de la Universidad de ChilePor Eugenio GonzĂĄlez Â
Time at a Standstill: Some Remarks on Acceleration and Subjectivity
From an experiential point of view, acceleration is a space-shrinking and a time-stressing phenomenon. Assuming that this phenomenon has reached a decisive pervasiveness in late modernity, so that it has become determinative of social relations in general, a question about its impact on the structure of experience and of the subject of experience bears a double signification: on the one hand, it concerns temporality, i.e., the structure of the experience of time, and, on the other hand, it concerns historicity, that is, the structure of the experience of historical time. I suppose that the development of this question requires examining the structure of the experience of the present, given that acceleration may be considered at first sight as an intensive experience of the present. But, then, an examination of the structure of the experience of the present is deeply rooted in the structure of the present itself. So, my argument relates three concepts: experience, present, and acceleration, the latter according to the double effect in which this phenomenon appears (spaceshrinking and time-stressing)
H^+_2$ in a strong magnetic field described via a solvable model
We consider the hydrogen molecular ion in the presence of a strong
homogeneous magnetic field. In this regime, the effective Hamiltonian is almost
one dimensional with a potential energy which looks like a sum of two Dirac
delta functions. This model is solvable, but not close enough to our exact
Hamiltonian for relevant strenght of the magnnetic field. However we show that
the correct values of the equilibrium distance as well as the binding energy of
the ground state of the ion, can be obtained when incorporating perturbative
corrections up to second order. Finally, we show that exists for
sufficiently large magnetic fields
Synthesis and morphological characterization of nanocomposite based on anodic TiO2 nanotubes and poly(N-maleoyl Glycine-CO-Acrylic acid)
IndexaciĂłn: Scopus.In this study, we examined the synthesis, and characterization of TiO2/poly(N-maleoylglycine-co-acrylic acid) (TiO2/poly(MG-co-AA)) nanocomposite. The nanocomposite was prepared by the dispersion of TiO2 nanotubes in a water solution of the polymer (3% w/w) and then it was lyophilized. The nanocomposite was characterized by FTIR and Raman spectroscopies. The incorporation of TiO2 nanotubes to the polymeric matrix was determined by transmission electron microscopy (TEM) from which TiO2 nanotubes in the inner of copolymer with diameters ranging between 90 and 100 nm were observed. The overall morphology of the previously synthetized nanotubes was determined by scanning electron microscopy (SEM). For the nanocomposite system, the morphology was studied by atomic force microscopy (AFM) from which a grain shape structure was observed. This process resulted in a new nanocompsite material with an average grain diameter estimated by SEM and AFM ranging between 210-240 nm. It was observed that the nanotubes were homogeneously dispersed within the polymeric matrix. The prepared material could be suitable in the design of electronic devices and additionally could have potential applications as biomaterial.https://scielo.conicyt.cl/pdf/jcchems/v62n3/0717-9324-jcchems-62-03-3634.pd
The Proteome of Biologically Active Membrane Vesicles from Piscirickettsia salmonis LF-89 Type Strain Identifies Plasmid-Encoded Putative Toxins
IndexaciĂłn: Scopus.Piscirickettsia salmonis is the predominant bacterial pathogen affecting the Chilean salmonid industry. This bacterium is the etiological agent of piscirickettsiosis, a significant fish disease. Membrane vesicles (MVs) released by P. salmonis deliver several virulence factors to host cells. To improve on existing knowledge for the pathogenicity-associated functions of P. salmonis MVs, we studied the proteome of purified MVs from the P. salmonis LF-89 type strain using multidimensional protein identification technology. Initially, the cytotoxicity of different MV concentration purified from P. salmonis LF-89 was confirmed in an in vivo adult zebrafish infection model. The cumulative mortality of zebrafish injected with MVs showed a dose-dependent pattern. Analyses identified 452 proteins of different subcellular origins; most of them were associated with the cytoplasmic compartment and were mainly related to key functions for pathogen survival. Interestingly, previously unidentified putative virulence-related proteins were identified in P. salmonis MVs, such as outer membrane porin F and hemolysin. Additionally, five amino acid sequences corresponding to the Bordetella pertussis toxin subunit 1 and two amino acid sequences corresponding to the heat-labile enterotoxin alpha chain of Escherichia coli were located in the P. salmonis MV proteome. Curiously, these putative toxins were located in a plasmid region of P. salmonis LF-89. Based on the identified proteins, we propose that the protein composition of P. salmonis LF-89 MVs could reflect total protein characteristics of this P. salmonis type strain. © 2017 Oliver, HernĂĄndez, Tandberg, Valenzuela, Lagos, Haro, SĂĄnchez, Ruiz, Sanhueza-OyarzĂșn, CortĂ©s, Villar, Artigues, Winther-Larsen, Avendaño-Herrera and Yåñez.https://www.frontiersin.org/articles/10.3389/fcimb.2017.00420/ful
Revised timing of cenozoic atlantic incursions and changing hinterland sediment sources during southern patagonian orogenesis
New detrital zircon U-Pb geochronology data from the Cenozoic Magallanes-Austral Basin in Argentina and Chile ~51° S establish a revised chronostratigraphy of Paleocene-Miocene foreland synorogenic strata and document the rise and subsequent isolation of hinterland sources in the Patagonian Andes from the continental margin. The upsection loss of zircons derived from the hinterland Paleozoic and Late Jurassic sources between ca. 60 and 44Ma documents a major shift in sediment routing due to Paleogene orogenesis in the greater Patagonian-Fuegian Andes. Changes in the proportion of grains from hinterland thrust sheets, comprised of Jurassic volcanics and Paleozoic metasedimentary rocks, provide a trackable signal of long-term shifts in orogenic drainage divide and topographic isolation due to widening of the retroarc fold-thrust belt. The youngest detrital zircon U-Pb ages confirm timing of Maastrichtian-Eocene strata but require substantial age revisions for part of the overlying Cenozoic basinfill during the late Eocene and Oligocene. The upper RĂo Turbio Formation, previously mapped as middle to late Eocene in the published literature, records a newly recognized latest Eocene-Oligocene (37-27Ma) marine incursion along the basin margin. We suggest that these deposits could be genetically linked to the distally placed units along the Atlantic coast, including the El Huemul Formation and the younger San JuliĂĄn Formation, via an eastward deepening within the foreland basin system that culminated in a basin-wide Oligocene marine incursion in the Southern Andes. The overlying RĂo Guillermo Formation records onset of tectonically generated coarse-grained detritus ca. 24.3Ma and a transition to the first fully nonmarine conditions on the proximal Patagonian platform since Late Cretaceous time, perhaps signaling a Cordilleran-scale upper plate response to increased plate convergence and tectonic plate reorganization.Fil: Fosdick, Julie C.. University of Connecticut; Estados UnidosFil: VanderLeest, R. A.. University of Connecticut; Estados UnidosFil: Bostelmann, J. E.. Universidad de Chile; ChileFil: Leonard, J. S.. Arizona State University; Estados UnidosFil: Ugalde, R.. Universidad Mayor; ChileFil: OyarzĂșn, J. L.. Parque Geo-paleontolĂłgico la Cumbre-baguales; ChileFil: Griffin, Miguel. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. DivisiĂłn PaleozoologĂa Invertebrados; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata; Argentin
AnĂĄlisis de los patrones instruccionales en las clases de resoluciĂłn de problemas matemĂĄticos verbales
En este estudio se analizan los patrones instruccionales en las clases de segundo ciclo de enseñanza bĂĄsica destinados a la resoluciĂłn de problemas (RP) matemĂĄticos. Se analizan muestras de la EvaluaciĂłn Docente 2013 identificando las actividades tĂpicas de aula, las estructuras de participaciĂłn y las ayudas otorgadas por los profesores. Si bien esta investigaciĂłn se encuentra en curso, se presentan los primeros hallazgos pertenecientes a 10 profesores mediante un anĂĄlisis del discurso y un anĂĄlisis cuantitativo de tipo de descriptivo. Los resultados arrojan once actividades tĂpicas de aula, que la estructura de participaciĂłn recae en los profesores y que son diez las ayudas mĂĄs utilizadas durante las sesiones de clase de RP
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