7,316 research outputs found
Dos visiones de la integración americana : Comentarios reales, del inca Garcilaso de la Vega y Crónica mexicana, de Fernando Alvarado Tezozómoc
1 archivo PDF (16 páginas). fhquadragintaDos cronistas mestizos, Garcilaso de la Vega El Inca en el Perú (hijo de español con princesa quéchua) y Fernando Alvarado Tezozómoc, indígena puro pero ya “mestizado” culturalmente y de la casa real de Texcoco, tratan en dos obras (“Comentarios reales”, el primero, y “Crónica mexicáyotl” el segundo), la figura de dos mitos fundacionales de sus orígenes: Viracocha y Quetzalcóatl. El estudio presente establece semejanzas y diferencias en su conceptualización y pretende mostrar las afinidades entre ambos tratamientos y sus diversas connotaciones
Los restos de José María Heredia, Santiago de Cuba, 1803- Ciudad de México, 1839 : detrás de los huesos perdidos o ¿La paz de los sepulcros?
1 archivo PDF (16 páginas). fhduodequadragintaA partir de la búsqueda de los restos mortales del escritor y político cubanomexicano José María Heredia, se realiza una revisión del estado de los sitios de enterramiento en la Ciudad de México entre 1839 y los siguientes años hasta finales del siglo XIX, en una época que incluye las diversas disposiciones de los gobiernos liberales mexicanos en cuanto a los panteones y cementerios, hasta entonces propiedad de la Iglesia
Multirobot heterogeneous control considering secondary objectives
Cooperative robotics has considered tasks that are executed frequently, maintaining the
shape and orientation of robotic systems when they fulfill a common objective, without taking
advantage of the redundancy that the robotic group could present. This paper presents a proposal
for controlling a group of terrestrial robots with heterogeneous characteristics, considering primary
and secondary tasks thus that the group complies with the following of a path while modifying its
shape and orientation at any time. The development of the proposal is achieved through the use
of controllers based on linear algebra, propounding a low computational cost and high scalability
algorithm. Likewise, the stability of the controller is analyzed to know the required features that have
to be met by the control constants, that is, the correct values. Finally, experimental results are shown
with di erent configurations and heterogeneous robots, where the graphics corroborate the expected
operation of the proposalThis research was funded by Corporación Ecuatoriana para el Desarrollo de la Investigación
y Academia–CEDI
DNA replication and replication stress response in the context of nuclear architecture
The DNA replication process needs to be coordinated with other DNA metabolism transactions and must eventually extend to the full genome, regardless of chromatin status, gene expression, secondary structures and DNA lesions. Completeness and accuracy of DNA replication are crucial to maintain genome integrity, limiting transformation in normal cells and offering targeting opportunities for proliferating cancer cells. DNA replication is thus tightly coordinated with chromatin dynamics and 3D genome architecture, and we are only beginning to understand the underlying molecular mechanisms. While much has recently been discovered on how DNA replication initiation is organised and modulated in different genomic regions and nuclear territories-the so-called "DNA replication program"-we know much less on how the elongation of ongoing replication forks and particularly the response to replication obstacles is affected by the local nuclear organisation. Also, it is still elusive how specific components of nuclear architecture participate in the replication stress response. Here, we review known mechanisms and factors orchestrating replication initiation, and replication fork progression upon stress, focusing on recent evidence linking genome organisation and nuclear architecture with the cellular responses to replication interference, and highlighting open questions and future challenges to explore this exciting new avenue of research
Dynamic Daylight Metrics for Electricity Savings in Offices: Window Size and Climate Smart Lighting Management
Daylight performance metrics provide a promising approach for the design and
optimization of lighting strategies in buildings and their management. Smart controls for electric
lighting can reduce power consumption and promote visual comfort using different control strategies,
based on affordable technologies and low building impact. The aim of this research is to assess the
energy efficiency of these smart controls by means of dynamic daylight performance metrics, to
determine suitable solutions based on the geometry of the architecture and the weather conditions.
The analysis considers different room dimensions, with variable window size and two mean surface
reflectance values. DaySim 3.1 lighting software provides the simulations for the study, determining
the necessary quantification of dynamic metrics to evaluate the usefulness of the proposed smart
controls and their impact on energy efficiency. The validation of dynamic metrics is carried out by
monitoring a mesh of illuminance-meters in test cells throughout one year. The results showed that,
for most rooms more than 3.00 m deep, smart controls achieve worthwhile energy savings and a low
payback period, regardless of weather conditions and for worst-case situations. It is also concluded
that dimming systems provide a higher net present value and allow the use of smaller window size
than other control solutions
Polarization of the changing-look quasar J1011+5442
If the disappearance of the broad emission lines observed in changing-look
quasars were caused by the obscuration of the quasar core through moving dust
clouds in the torus, high linear polarization typical of type 2 quasars would
be expected. We measured the polarization of the changing-look quasar
J1011+5442 in which the broad emission lines have disappeared between 2003 and
2015. We found a polarization degree compatible with null polarization. This
measurement suggests that the observed change of look is not due to a change of
obscuration hiding the continuum source and the broad line region, and that the
quasar is seen close to the system axis. Our results thus support the idea that
the vanishing of the broad emission lines in J1011+5442 is due to an intrinsic
dimming of the ionizing continuum source that is most likely caused by a rapid
decrease in the rate of accretion onto the supermassive black hole.Comment: Accepted for publication in Astronomy and Astrophysics Letter
HH 223: a parsec-scale H2 outflow in the star-forming region L723
The dark cloud Lynds 723 (L723) is a low-mass star-forming region where one
of the few known cases of a quadrupolar CO outflow has been reported. Two
recent works have found that the radio continuum source VLA 2, towards the
centre of the CO outflow, is actually a multiple system of young stellar
objects (YSOs). Several line-emission nebulae that lie projected on the
east-west CO outflow were detected in narrow-band Halpha and [SII] images. The
spectra of the knots are characteristic of shock-excited gas (Herbig-Haro
spectra), with supersonic blueshifted velocities, which suggests an optical
outflow also powered by the VLA 2 YSO system of L723. We imaged a field of ~5'
X 5' centred on HH 223, which includes the whole region of the quadrupolar CO
outflow with nir narrow-band filters . The H2 line-emission structures appear
distributed over a region of 5.5' (0.5 pc for a distance of 300 pc) at both
sides of the VLA 2 YSO system, with an S-shape morphology, and are projected
onto the east-west CO outflow. Most of them were resolved in smaller knotty
substructures. The [FeII] emission only appears associated with HH 223. An
additional nebular emission from the continuum in Hc and Kc appears associated
with HH 223-K1, the structure closest to the VLA 2 YSO system, and could be
tracing the cavity walls. We propose that the H2 structures form part of a
large-scale near-infrared outflow, which is also associated with the VLA 2 YSO
system. The current data do not allow us to discern which of the YSOs of VLA 2
is powering this large scale optical/near-infrared outflow.Comment: Accepted for A&A http://dx.doi.org/10.1051/0004-6361/201015125 12
pages, 9 figure
Hexavalent Chromium Removal by a Paecilomyces sp. Fungal Strain Isolated from Environment
A resistant and capable fungal strain in removing hexavalent chromium was isolated from an environment near of Chemical Science Faculty, located in the city of San Luis Potosí, Mexico. The strain was identified as Paecilomyces sp., by macro- and microscopic characteristics. Strain resistance of the strain to high Cr (VI) concentrations and its ability to reduce chromium were studied. When it was incubated in minimal medium with glucose, another inexpensive commercial carbon source like unrefined and brown sugar or glycerol, in the presence of 50 mg/L of Cr (VI), the strain caused complete disappearance of Cr (VI), with the concomitant production of Cr (III) in the growth medium after 7 days of incubation, at 28°C, pH 4.0, 100 rpm, and an inoculum of 38 mg of dry weight. Decrease of Cr (VI) levels from industrial wastes was also induced by Paecilomyces biomass. These results indicate that reducing capacity of chromate resistant filamentous fungus Cr (VI) could be useful for the removal of Cr (VI) pollution
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