29 research outputs found
Material flow analysis in indentation process by 3D Digital Image Correlation
Focusing in the application of the 3D Digital Image Correlation technique, this work proposes a material flow analysis in an indentation process. The study establishes the methodology for the calibration and implementation of the 3D image sensing technology for deformation measurements. The purpose is to continue with the validation of the DIC application to the indentation processes, where a deep penetration is achieved and extensive material flow is produced. With the 3D DIC technique is possible to perform accurate deformation measurements in not planar specimens and study the material emerging towards the exterior of the tested specimen, which is not possible with the 2D DIC technique. Although previous 2D studies were efficient detecting the flow field and von Mises strains on the specimens tested, the bulge emerging under the punch on the front surface (dead zone) could not be studied due to its predominantly 3D character. Therefore, present work implements a 3D methodology that carries out a complete study of the deformation, including the material flow that occurs on the Z axis, towards the exterior of the tested specimen, optimizing previous analyses.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
An L-type substellar object in Orion: reaching the mass boundary between brown dwarfs and giant planets
We present J-band photometry and low-resolution optical spectroscopy
(600-1000 nm) for one of the faintest substellar member candidates in the young
sigma Ori cluster, SOri 47 (I=20.53, Bejar et al. 1999). Its very red
(I-J)=3.3+/-0.1 color and its optical spectrum allow us to classify SOri 47 as
an L1.5-type object which fits the low-luminosity end of the cluster
photometric and spectroscopic sequences. It also displays atmospheric features
indicative of low gravity such as weak alkaline lines and hydride and oxide
bands, consistent with the expectation for a very young object still undergoing
gravitational collapse. Our data lead us to conclude that SOri 47 is a true
substellar member of the sigma Ori cluster. Additionally, we present the
detection of LiI in its atmosphere which provides an independent confirmation
of youth and substellarity. Using current theoretical evolutionary tracks and
adopting an age interval of 1-5 Myr for the sigma Ori cluster, we estimate the
mass of SOri 47 at 0.015+/-0.005 Msun, i.e. at the minimum mass for deuterium
burning, which has been proposed as a definition for the boundary between brown
dwarfs and giant planets. SOri 47 could well be the result of a natural
extension of the process of cloud fragmentation down to the deuterium burning
mass limit; a less likely alternative is that it has originated from a
protoplanetary disc around a more massive cluster member and later ejected from
its orbit due to interacting effects within this rather sparse (~12
objects/pc^3) young cluster.Comment: 9 pages, 3 figures, accepted for publication in ApJ Letter
Pleiades low-mass brown dwarfs: the cluster L dwarf sequence
We present a search for low-mass brown dwarfs in the Pleiades open cluster.
The identification of Pleiades members fainter and cooler than those currently
known allows us to constrain evolutionary models for L dwarfs and to extend the
study of the cluster mass function to lower masses. We conducted a 1.8 deg^2
near-infrared J-band survey at the 3.5m Calar Alto Telescope, with completeness
J~19.0. The detected sources were correlated with those of previously available
optical I-band images (completeness I~22). Using a J versus I-J
colour-magnitude diagram, we identified 18 faint red L-type candidates, with
magnitudes 17.43.2. If Pleiades members, their masses
would span ~0.040-0.020 M_Sol. We performed follow-up HKs-band imaging to
further confirm their cluster membership by photometry and proper motion. Out
of 11 IJ candidates with proper motion measurements, we find six cluster
members, two non-members and three whose membership is uncertain and depends on
the intrinsic velocity dispersion of Pleiades brown dwarfs. This dispersion (>4
mas yr^-1) is at least four times that of cluster stars with masses >1 M_Sol.
Five of the seven other IJ candidates are discarded because their J-Ks colours
are bluer than those of confirmed members. The J versus I-J sequence of the
L-type candidates at J>18 is not as red as theoretical models predict; it
rather follows the field L-dwarf sequence translated to the cluster distance.
This sequence overlapping, also observed in the J versus J-H and J-K diagrams,
suggests that Pleiades and field L dwarfs may have similar spectral energy
distributions and luminosities, and thus possibly similar radii. Also, we find
alpha=0.5+-0.2 for a power-law approximation dN/dM propor. M^-alpha of the
survey mass spectrum in the mass range 0.5-0.026 M_Sol.Comment: 14 pages, 7 figures, accepted for publication in Astronomy and
Astrophysic
Shadows of the colonial past – diverging plant use in Northern Peru and Southern Ecuador
This paper examines the traditional use of medicinal plants in Northern Peru and Southern Ecuador, with special focus on the Departments of Piura, Lambayeque, La Libertad, Cajamarca, and San Martin, and in Loja province, with special focus on the development since the early colonial period. Northern Peru represents the locus of the old Central Andean "Health Axis." The roots of traditional healing practices in this region go as far back as the Cupisnique culture early in the first millennium BC
Search for flavour-changing neutral current top quark decays t → Hq in pp collisions at √s=8 TeV with the ATLAS detector
A search for flavour-changing neutral current decays of a top quark to an uptype quark (q = u, c) and the Standard Model Higgs boson, where the Higgs boson decays to bb¯, is presented. The analysis searches for top quark pair events in which one top quark decays to Wb, with the W boson decaying leptonically, and the other top quark decays to Hq. The search is based on pp collisions at √s=8 TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and uses an integrated luminosity of 20.3 fb−1. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon and at least four jets. The search exploits the high multiplicity of b-quark jets characteristic of signal events, and employs a likelihood discriminant that uses the kinematic differences between the signal and the background, which is dominated by tt¯→WbWb decays. No significant excess of events above the background expectation is found, and observed (expected) 95% CL upper limits of 0.56% (0.42%) and 0.61% (0.64%) are derived for the t → Hc and t → Hu branching ratios respectively. The combination of this search with other ATLAS searches in the H → γγ and H → WW*, ττ decay modes significantly improves the sensitivity, yielding observed (expected) 95% CL upper limits on the t → Hc and t → Hu branching ratios of 0.46% (0.25%) and 0.45% (0.29%) respectively. The corresponding combined observed (expected) upper limits on the |λtcH| and |λtuH| couplings are 0.13 (0.10) and 0.13 (0.10) respectively. These are the most restrictive direct bounds on tqH interactions measured so far
Traditional medicinal plant use in Northern Peru: tracking two thousand years of healing culture
This paper examines the traditional use of medicinal plants in Northern Peru, with special focus on the Departments of Piura, Lambayeque, La Libertad, Cajamarca, and San Martin. Northern Peru represents the center of the old Central Andean "Health Axis," stretching from Ecuador to Bolivia. The roots of traditional healing practices in this region go at least as far back as the Moche period (AC 100–800). Although about 50% of the plants in use reported in the colonial period have disappeared from the popular pharmacopoeia, the plant knowledge of the population is much more extensive than in other parts of the Andean region. 510 plant species used for medicinal purposes were collected, identified and their vernacular names, traditional uses and applications recorded. The families best represented were Asteraceae with 69 species, Fabaceae (35), Lamiaceae (25), and Solanaceae (21). Euphorbiaceae had twelve species, and Apiaceae and Poaceae 11 species. The highest number of species was used for the treatment of "magical/ritual" ailments (207 species), followed by respiratory disorders (95), problems of the urinary tract (85), infections of female organs (66), liver ailments (61), inflammations (59), stomach problems (51) and rheumatism (45). Most of the plants used (83%) were native to Peru. Fresh plants, often collected wild, were used in two thirds of all cases, and the most common applications included the ingestion of herb decoctions or the application of plant material as poultices
Surface Gravities for 228 M, L, and T Dwarfs in the NIRSPEC Brown Dwarf Spectroscopic Survey
Fish ES cells and applications to biotechnology
10.1007/s10126-006-6034-4Marine Biotechnology92117-127MABI
Magnetic fields in M dwarfs from the CARMENES survey
Context. M dwarfs are known to generate the strongest magnetic fields among main-sequence stars with convective envelopes, but we are still lacking a consistent picture of the link between the magnetic fields and underlying dynamo mechanisms, rotation, and activity. Aims: In this work we aim to measure magnetic fields from the high-resolution near-infrared spectra taken with the CARMENES radial-velocity planet survey in a sample of 29 active M dwarfs and compare our results against stellar parameters. Methods: We used the state-of-the-art radiative transfer code to measure total magnetic flux densities from the Zeeman broadening of spectral lines and filling factors. Results: We detect strong kG magnetic fields in all our targets. In 16 stars the magnetic fields were measured for the first time. Our measurements are consistent with the magnetic field saturation in stars with rotation periods P < 4 d. The analysis of the magnetic filling factors reveal two different patterns of either very smooth distribution or a more patchy one, which can be connected to the dynamo state of the stars and/or stellar mass. Conclusions: Our measurements extend the list of M dwarfs with strong surface magnetic fields. They also allow us to better constrain the interplay between the magnetic energy, stellar rotation, and underlying dynamo action. The high spectral resolution and observations at near-infrared wavelengths are the beneficial capabilities of the CARMENES instrument that allow us to address important questions about the stellar magnetism