95 research outputs found
La inhibición de la síntesis de óxido nítrico durante la colestasis inducida experimentalmente reduce la lesión hepatocelular al facilitar la homeostasis de nitrosotioles
Comunicaciones a congreso
Uso de la autoevaluación para mejorar destrezas orales del idioma inglés de los estudiantes, en la enseñanza virtual
The evaluation and scoring of spoken English during virtual classes has become a common task in public schools. Several teachers have identified various challenges, such as the student's limited language proficiency, lack of prior knowledge of English, student dependency on the teacher, poor exposure to English outside the classroom, lack of consistency in student performance. student and teachers' limited expectations of what students can achieve, as well as the scarcity of technological devices that support development in the use of language platforms and courses. The main objective of this research is to improve students' English proficiency by using self-assessment in collaboration with Flipgrid, an online tool that allows users to create audio recordings and short videos. The methodology used is based on action research with an interpretive approach to analyze the environment and seek solutions through open research. The population under study includes a group of students with whom virtual English classes were carried out. The findings obtained facilitate feedback and foster a supportive learning environment as means that contribute to the progress of students, providing them with the opportunity to take corrective measures in their learning process.La evaluación y puntuación del inglés hablado durante las clases virtuales se ha convertido en una tarea común en las escuelas públicas. Varios maestros han identificado diversos desafíos, como la limitada competencia del estudiante en el idioma, la falta de conocimientos previos de inglés, la dependencia del estudiante en el maestro, la escasa exposición al inglés fuera del aula, la falta de coherencia en el desempeño del estudiante y las expectativas limitadas de los maestros sobre lo que los estudiantes pueden lograr, así como la escasez de dispositivos tecnológicos que apoyen el desarrollo en el uso de plataformas y cursos de idiomas. El principal objetivo de esta investigación es mejorar la competencia en inglés, de los estudiantes, mediante el uso de la autoevaluación en colaboración con Flipgrid, una herramienta en línea que permite a los usuarios crear grabaciones de audio y videos cortos. La metodología empleada se basa en la investigación-acción con un enfoque interpretativo para analizar el entorno y buscar soluciones a través de una investigación abierta. La población objeto de estudio incluye un grupo de estudiantes con los cuales se llevaron a cabo clases virtuales de inglés. Los hallazgos obtenidos facilitan la retroalimentación y fomentan un entorno de aprendizaje de apoyo como medios que contribuyen al progreso de los estudiantes, brindándoles la oportunidad de tomar medidas correctivas en su proceso de aprendizaje
Star-forming Clumps in Local Luminous Infrared Galaxies
We present HST narrowband near-infrared imaging of Paα and Paβ emission of 48 local luminous infrared galaxies (LIRGs) from the Great Observatories All-Sky LIRG Survey. These data allow us to measure the properties of 810 spatially resolved star-forming regions (59 nuclei and 751 extranuclear clumps) and directly compare their properties to those found in both local and high-redshift star-forming galaxies. We find that in LIRGs the star-forming clumps have radii ranging from ~90 to 900 pc and star formation rates (SFRs) of ~1 × 10⁻³ to 10 M⊙ yr⁻¹, with median values for extranuclear clumps of 170 pc and 0.03 M⊙ yr⁻¹. The detected star-forming clumps are young, with a median stellar age of 8.7 Myr, and have a median stellar mass of 5 × 10⁵ M ⊙. The SFRs span the range of those found in normal local star-forming galaxies to those found in high-redshift star-forming galaxies at z = 1–3. The luminosity function of the LIRG clumps has a flatter slope than found in lower-luminosity, star-forming galaxies, indicating a relative excess of luminous star-forming clumps. In order to predict the possible range of star-forming histories and gas fractions, we compare the star-forming clumps to those measured in the MassiveFIRE high-resolution cosmological simulation. The star-forming clumps in MassiveFIRE cover the same range of SFRs and sizes found in the local LIRGs and have total gas fractions that extend from 10% to 90%. If local LIRGs are similar to these simulated galaxies, we expect that future observations with ALMA will find a large range of gas fractions, and corresponding star formation efficiencies, among the star-forming clumps in LIRGs
C-GOALS II. Chandra Observations of the Lower Luminosity Sample of Nearby Luminous Infrared Galaxies in GOALS
We analyze Chandra X-ray observatory data for a sample of 63 luminous
infrared galaxies (LIRGs), sampling the lower-infrared luminosity range of the
Great Observatories All-Sky LIRG survey (GOALS), which includes the most
luminous infrared selected galaxies in the local universe. X-rays are detected
for 84 individual galaxies within the 63 systems, for which arcsecond
resolution X-ray images, fluxes, infrared and X-ray luminosities, spectra and
radial profiles are presented. Using X-ray and MIR selection criteria, we find
AGN in (315)% of the galaxy sample, compared to the (386)% previously
found for GOALS galaxies with higher infrared luminosities (C-GOALS I). Using
mid-infrared data, we find that (599)% of the X-ray selected AGN in the
full C-GOALS sample do not contribute significantly to the bolometric
luminosity of the host galaxy. Dual AGN are detected in two systems, implying a
dual AGN fraction in systems that contain at least one AGN of (2914)%,
compared to the (1110)% found for the C-GOALS I sample. Through analysis
of radial profiles, we derive that most sources, and almost all AGN, in the
sample are compact, with half of the soft X-ray emission generated within the
inner kpc. For most galaxies, the soft X-ray sizes of the sources are
comparable to those of the MIR emission. We also find that the hard X-ray
faintness previously reported for the bright C-GOALS I sources is also observed
in the brightest LIRGs within the sample, with
L.Comment: 24 pages, 13 figures, 11 tables, accepted for publication in A&
A 33 GHz Survey of Local Major Mergers: Estimating the Sizes of the Energetically Dominant Regions from High Resolution Measurements of the Radio Continuum
We present Very Large Array observations of the 33 GHz radio continuum
emission from 22 local ultraluminous and luminous infrared (IR) galaxies
(U/LIRGs). These observations have spatial (angular) resolutions of 30--720 pc
(0.07"-0.67") in a part of the spectrum that is likely to be optically thin.
This allows us to estimate the size of the energetically dominant regions. We
find half-light radii from 30 pc to 1.7 kpc. The 33 GHz flux density correlates
well with the IR emission, and we take these sizes as indicative of the size of
the region that produces most of the energy. Combining our 33 GHz sizes with
unresolved measurements, we estimate the IR luminosity and star formation rate
per area, and the molecular gas surface and volume densities. These quantities
span a wide range (4 dex) and include some of the highest values measured for
any galaxy (e.g., ). At least sources appear Compton thick (). Consistent with previous work, contrasting these data
with observations of normal disk galaxies suggests a nonlinear and likely
multi-valued relation between SFR and molecular gas surface density, though
this result depends on the adopted CO-to-H conversion factor and the
assumption that our 33 GHz sizes apply to the gas. 11 sources appear to exceed
the luminosity surface density predicted for starbursts supported by radiation
pressure and supernovae feedback, however we note the need for more detailed
observations of the inner disk structure. U/LIRGs with higher surface
brightness exhibit stronger [{\sc Cii}] 158m deficits, consistent with the
suggestion that high energy densities drive this phenomenon.Comment: 32 pages, 11 figures, 7 tables. Accepted for publication in Ap
Sub-arcsecond imaging of Arp\,299-A at 150 MHz with LOFAR: Evidence for a starburst-driven outflow
We report on the first sub-arcsecond (0.44 0.41 arcsec)
angular resolution image at 150 MHz of the A-nucleus in the Luminous Infrared
Galaxy Arp299, from International Low Frequency Array (LOFAR) Telescope
observations. The most remarkable finding is that of an intriguing two-sided,
filamentary structure emanating from A-nucleus, which we interpret as an
outflow that extends up to at least 14 arcseconds from the A-nucleus in the N-S
direction ( 5 kpc deprojected size) and accounts for almost 40% of the
extended emission of the entire galaxy system. We also discuss HST/NICMOS
[FeII] 1.64 and H 2.12 images of Arp299-A,
which show similar features to those unveiled by our 150 MHz LOFAR
observations, thus giving string morphological support for the outflow
scenario. Finally, we discuss unpublished NaI D spectra that confirm the
outflow nature of this structure. From energetic arguments, we rule out the
low-luminosity active galactic nucleus in Arp299-A as a driver for the
outflow. On the contrary, the powerful, compact starburst in the central
regions of Arp299-A provides plenty of mechanical energy to sustain an
outflow, and we conclude that the intense supernova (SN) activity in the
nuclear region of Arp299-A is driving the observed outflow. We estimate that
the starburst wind can support a mass-outflow rate in the range (11-63) at speeds of up to (370 - 890) , and is
relatively young, with an estimated kinematic age of (3 - 7) Myr. Those results
open an avenue to the use of low-frequency (150 MHz), sub-arcsecond imaging
with LOFAR to detect outflows in the central regions of local luminous infrared
galaxies
Nuclear Translocation of b-Catenin during Mesenchymal Stem Cells Differentiation into Hepatocytes Is Associated with a Tumoral Phenotype
Wnt/b-catenin pathway controls biochemical processes related to cell differentiation. In committed cells the alteration of
this pathway has been associated with tumors as hepatocellular carcinoma or hepatoblastoma. The present study evaluated
the role of Wnt/b-catenin activation during human mesenchymal stem cells differentiation into hepatocytes. The
differentiation to hepatocytes was achieved by the addition of two different conditioned media. In one of them, b-catenin
nuclear translocation, up-regulation of genes related to the Wnt/b-catenin pathway, such as Lrp5 and Fzd3, as well as the
oncogenes c-myc and p53 were observed. While in the other protocol there was a Wnt/b-catenin inactivation. Hepatocytes
with nuclear translocation of b-catenin also had abnormal cellular proliferation, and expressed membrane proteins involved
in hepatocellular carcinoma, metastatic behavior and cancer stem cells. Further, these cells had also increased auto-renewal
capability as shown in spheroids formation assay. Comparison of both differentiation protocols by 2D-DIGE proteomic
analysis revealed differential expression of 11 proteins with altered expression in hepatocellular carcinoma. Cathepsin B and
D, adenine phosphoribosyltransferase, triosephosphate isomerase, inorganic pyrophosphatase, peptidyl-prolyl cis-trans
isomerase A or lactate dehydrogenase b-chain were up-regulated only with the protocol associated with Wnt signaling
activation while other proteins involved in tumor suppression, such as transgelin or tropomyosin b-chain were downregulated
in this protocol. In conclusion, our results suggest that activation of the Wnt/b-catenin pathway during human
mesenchymal stem cells differentiation into hepatocytes is associated with a tumoral phenotyp
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