4,108 research outputs found
Modelling the squeeze flow in a deformed rectangular microchannel
Universidad de Málaga. Campus de Excelencia Internacional AndalucÃa Tech.Rheinforce cork composites, previously named elsewhere as CorkSTFluidics [1], are sandwiches consis?ng of two microagglomerated cork pads embedding microfluidic
paCerns that are filled with a shear thickening fluid (see Figure 1 (a)), whose mechanical performance under impact loads is determined by the microfluidic paCern and the
rheological proper?es of the fluid [2]. From the experimental results it is impossible to decouple the fluid contribu?on from the solid contribu?on to the force?me response
of the composite. In this work, we have developed a simple model of the fluid-flow dynamics that it is able to predict the fluid contribu?on in the energy dissipa?on of the
Rheinforce cork composites under impact loads. To that end, we model the viscous flow inside a microchannel for a known displacement of the upper lid h(t, x), calcula?ng
as a result the needed force to create that movement
A Quasar Microlensing Light Curve Generator for LSST
We present a tool to generate mock quasar microlensing light curves and
sample them according to any observing strategy. An updated treatment of the
fixed and random velocity components of observer, lens, and source is used,
together with a proper alignment with the external shear defining the
magnification map caustic orientation. Our tool produces quantitative results
on high magnification events and caustic crossings, which we use to study three
lensed quasars known to display microlensing, viz. RX J1131-1231, HE 0230-2130,
and Q 2237+0305, as they would be monitored by The Rubin Observatory Legacy
Survey of Space and Time (LSST). We conclude that depending on the location on
the sky, the lens and source redshift, and the caustic network density, the
microlensing variability may deviate significantly than the expected
20-year average time scale (Mosquera & Kochanek 2011, arXiv:1104.2356).
We estimate that high magnification events with mag mag
could potentially be observed by LSST each year. The duration of the majority
of high magnification events is between 10 and 100 days, requiring a very high
cadence to capture and resolve them. Uniform LSST observing strategies perform
the best in recovering microlensing high magnification events. Our web tool can
be extended to any instrument and observing strategy, and is freely available
as a service at http://gerlumph.swin.edu.au/tools/lsst_generator/, along with
all the related code.Comment: 10 pages, 6 figures, 2 tables. Published in MNRAS. Updated Table
Transition to turbulence in the bottom boundary layer under a solitary wave.
Se estudia la transición a la turbulencia en una capa lÃmite oscilatoria.Se estudia la transición a la turbulencia en una capa lÃmite oscilatoria.Universidad de Málaga. Campus de Excelencia Internacional AndalucÃa Tech
At-sea abundance and distribution of skuas and jaegers (Charadriiformes: Stercorariidae) at coastal waters off central Chile
Indexación: Web of Science; Scielo.BACKGROUND: Skuas and jaegers (Charadriiformes: Stercorariidae) are seabirds breeding at moderate to high latitudes and some perform extensive post-breeding transequatorial migrations. Most species overwinter and perform significant portions of their migratory flyways along the Pacific coast of South America, but scant information is available on their at-sea ecology in this waters. Our aims in this study were to determine: 1) the timing of occurrence and fluctuations in abundance of skua and jaeger species, 2) their spatial distribution within the coastal zone and 3) at-sea behavior of birds, including flock size and interactions with other seabird species.
RESULTS: Between July 2006 and October 2013, we conducted at-sea bird counts at Valparaiso Bay (33°S) in central Chile and confirmed the occurrence of Chilean skuas (Stercorarius chilensis), Brown skuas (S. antarcticus), and Parasitic jaegers (S. parasiticus). Parasitic jaegers are regular austral summer visitors (November to March), whereas Brown skuas occur in the area only in winter (July to October). Chilean skuas were regularly recorded year-round in the area with higher abundances between late winter and early spring (August to October). Brown and Chilean skuas where observed comparatively offshore, whereas Jaegers presented a more coastal distribution, probably associated to host presence. Chilean skuas kleptoparasitized similar-sized (shearwaters and fulmars) and larger seabird species (boobies), whereas jaegers chased only smaller coastal birds (gulls and terns). Brown skuas engaged in no kleptoparasitic behaviors. All three species were observed mostly as solitary individuals.
CONCLUSIONS: Skuas and jaegers showed in general a marked seasonality in their occurrence and abundance (only Chilean skua occurs year-round) and use this area as a commuting and stopover zone within their extensive migratory flyway along the southeastern Pacific.http://ref.scielo.org/p7thp
The different origins of high- and low-ionization broad emission lines revealed by gravitational microlensing in the Einstein cross
We investigate the kinematics and ionization structure of the broad emission
line region of the gravitationally lensed quasar QSO2237+0305 (the Einstein
cross) using differential microlensing in the high- and low-ionization broad
emission lines. We combine visible and near-infrared spectra of the four images
of the lensed quasar and detect a large-amplitude microlensing effect
distorting the high-ionization CIV and low-ionization H line profiles
in image A. While microlensing only magnifies the red wing of the Balmer line,
it symmetrically magnifies the wings of the CIV emission line. Given that the
same microlensing pattern magnifies both the high- and low-ionization broad
emission line regions, these dissimilar distortions of the line profiles
suggest that the high- and low-ionization regions are governed by different
kinematics. Since this quasar is likely viewed at intermediate inclination, we
argue that the differential magnification of the blue and red wings of
H favors a flattened, virialized, low-ionization region whereas the
symmetric microlensing effect measured in CIV can be reproduced by an emission
line formed in a polar wind, without the need of fine-tuned caustic
configurations.Comment: 11 pages, 4 figures, A&
El concepto de geosinclinal tras la revolución movilista: otro desajuste entre la ciencia actual y la ciencia en el aula
A revision of Geology and Physical Science textbooks widely used at high-school leve1 shows that the geosyncline idea (in itself or as a part of plate tectonics theory) is frequently presented as a tenable hypothesis on mountain origins. As this is not a scientifically acceptable position any more, a great deal of confusion is probably being created among both students and teachers without very solid geologic foundations
Historia y epistemologÃa de las ciencias: el concepto de geosinclinal tras la revolución movilista: otro desajuste entre la ciencia actual y la ciencia en el aula
Depto. de MineralogÃa y PetrologÃaFac. de Ciencias GeológicasFALSEpu
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