Process Chain for the Fabrication of a Custom 3D Barrier for Guided Bone Regeneration

Guided Bone Regeneration (GBR) is a surgical procedure that consists in the use of barrier membranes to cover bone defects caused by trauma, periodontal disease and other pathologies. These barriers allow the proliferation of bone cells, and prevent the invasion of the defect by non-osteogenic cells (connective and epithelium) in patients with a lack of horizontal and/or vertical bone. This process is essential for the successful dental implant placement. Additive manufacturing (AM) is emerging as an important tool for biomedical applications, especially for regenerative medicine and tissue engineering. This paper proposes a process chain for the fabrication of a custom barrier from cone beam computed tomography (CBCT) as Digital Imaging and Communication in Medicine (DICOM) files obtained from a patient with vertical bone resorption of the anterior maxilla.DICOM files have been processed with Invesalius 3.0 to obtain the tridimensional (3D) anatomy of the region of interest. This 3D model was cleaned, fixed, and smoothed. The prototyped model of the patient’s bone defect was further processed in Rhinoceros to offer a 3D architecture for cell growth. To obtain information of the thermal and mechanical properties a finite element method (FEM) was assessed. The prototype obtained was produced with fused deposition modeling (FDM) an additive manufacturing technology

A new L-dwarf member of the moderately metal-poor triple system HD 221356

We report on the discovery of a fourth component in the HD 221356 star system, previously known to be formed by an F8V, slightly metal-poor primary ([Fe/H]=-0.26), and a distant M8V+L3V pair. In our ongoing common proper motion search based on VISTA Hemisphere Survey (VHS) and 2MASS catalogues, we have detected a faint (J=13.76+/-0.04 mag) co-moving companion of the F8 star located at angular separation of 12.13+/-0.18 arcsec (position angle of 221.8+/-1.7), corresponding to a projected distance of ~312 AU at 26 pc. Near-infrared spectroscopy of the new companion, covering the 1.5-2.4 micron wavelength range with a resolving power of R~600, indicates an L1+/-1 spectral type. Using evolutionary models the mass of the new companion is estimated at ~0.08 solar masses, which places the object close to the stellar-substellar borderline. This multiple system provides an interesting example of objects with masses slightly above and below the hydrogen burning mass limit. The low mass companions of HD 221356 have slightly bluer colours than field dwarfs with similar spectral type, which is likely a consequence of the sub-solar metallicity of the system.Comment: 7 pages, 4 figures, accepted for publication in MNRA

Near-infrared Linear Polarization of Ultracool Dwarfs

We report on near-infrared J- and H-band linear polarimetric photometry of eight ultracool dwarfs (two late-M, five L0-L7.5, and one T2.5) with known evidence for photometric variability due to dust clouds, anomalous red infrared colors, or low-gravity atmospheres. The polarimetric data were acquired with the LIRIS instrument on the William Herschel Telescope. We also provide mid-infrared photometry in the interval 3.4-24 micron for some targets obtained with Spitzer and WISE, which has allowed us to confirm the peculiar red colors of five sources in the sample. We can impose modest upper limits of 0.9% and 1.8% on the linear polarization degree for seven targets with a confidence of 99%. Only one source, 2MAS, J02411151-0326587 (L0), appears to be strongly polarized (P ~ 3%) in the J-band with a significance level of P/sigma_P ~ 10. The likely origin of its linearly polarized light and rather red infrared colors may reside in a surrounding disk with an asymmetric distribution of grains. Given its proximity (66 +/- 8 pc), this object becomes an excellent target for the direct detection of the disk.Comment: Accepted for publication in Ap

Ultracool dwarf benchmarks with \emph{Gaia} primaries

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2017 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.We explore the potential of \emph{Gaia} for the field of benchmark ultracool/brown dwarf companions, and present the results of an initial search for metal-rich/metal-poor systems. A simulated population of resolved ultracool dwarf companions to \emph{Gaia} primary stars is generated and assessed. Of order $\sim$24,000 companions should be identifiable outside of the Galactic plane ($|b| > 10\,$deg) with large-scale ground- and space-based surveys including late M, L, T, and Y types. Our simulated companion parameter space covers $0.02 \le M/M_{\odot} \le 0.1$, $0.1 \le {\rm age/Gyr} \le 14$, and $-2.5 \le {\rm [Fe/H]} \le 0.5$, with systems required to have a false alarm probability $$0.6\, kau}\,Peer reviewedFinal Accepted Versio

Producción de biodiésel a partir de microalgas: avances y perspectivas biotecnológicas

Las microalgas son una alternativa para la obtención de biodiésel por su alto rendimiento de lípidos y su perfil de ácidos grasos. Objetivos. Hacer una revisión sobre los avances y perspectivas actuales de la producción de biodiésel a partir de microalgas. Métodos. Se realizó una búsqueda actualizada de los trabajos de investigación relacionados con la producción de biodiésel a partir de microalgas, con especial énfasis en la biosíntesis de ácidos grasos y triglicéridos, la producción de biomasa, las técnicas de extracción, los procesos biotecnológicos implementados en sistemas de cultivo, la transesterificación y los sistemas de doble propósito. Resultados. Las microalgas tienen rendimientos altos de producción de lípidos (59 m3 ha-1 año-1), por lo que representa una alternativa para la obtención de biodiésel; sin embargo, el costo de producción y recuperación de biomasa sigue siendo elevado ($5.8 USD Kg-1), aunado a los altos requerimientos energéticos (33 MJ Kg-1). Actualmente no existen técnicas industriales factibles para la extracción de lípidos y se están probando los métodos por fluidos supercríticos, campo eléctrico de pulso, microondas y ultrasonicación. La biotecnología ha propuesto un novedoso sistema biológico mediante el uso de lipasas recuperadas de hongos filamentosos para el proceso de transesterificación, los cuales ya son comerciales, y ha logrado rendimientos de biocatálisis mayores al 90%.Los sistema de doble propósito pueden ser optimizados utilizando un diseño modular que establezca los procesos y operaciones unitarias bien definidas. Conclusiones. El uso de microalgas para la obtención de biodiésel representa una técnica viable gracias a su alto contenido lipídico y a su perfil de ácidos grasos, aunque hace falta el desarrollo de tecnologías que disminuyan el costo de producción. El uso de sistemas de doble propósito se vislumbra como una buena opción para reducir estos precios, al mismo tiempo que se reusan aguas residuales

New isolated planetary mass objects and the stellar and substellar mass function of the sigma Orionis cluster

We report on our analysis of the VISTA Orion ZYJHKs photometric data (completeness magnitudes Z=22.6 and J=21.0mag) focusing on a circular area of 2798.4 arcmin^2 around the young sigma Orionis star cluster (~3Myr, ~352pc, solar metallicity). The combination of the VISTA photometry with optical, WISE and Spitzer data allows us to identify a total of 210 cluster member candidates with masses in the interval 0.25-0.004Msun, 23 of which are new planetary-mass object findings. These discoveries double the number of cluster planetary-mass candidates known so far. One object has colors compatible with a T spectral type. The cluster harbors about as many brown dwarfs (69, 0.072-0.012Msun) and planetary-mass objects (37, 0.012-0.004Msun) as very low-mass stars (104, 0.25-0.072Msun). Based on Spitzer data, we derive a disk frequency of ~40% for very low-mass stars, brown dwarfs, and planetary mass objects in sigma Orionis. The radial density distributions of these three mass intervals are alike: all are spatially concentrated within an effective radius of 12arcmin (1.2pc) around the multiple star sigma Ori, and no obvious segregation between disk-bearing and diskless objects is observed. Using the VISTA data and the Mayrit catalog, we derive the cluster mass spectrum (DeltaN/DeltaM ~ M^{-alpha}) from ~19 to 0.006Msun (VISTA ZJ completeness), which is reasonably described by two power-law expressions with indices of alpha=1.7+/-0.2 for M>0.35Msun, and alpha=0.6+/-0.2 for M<0.35Msun. The sigma Orionis mass spectrum smoothly extends into the planetary-mass regime down to 0.004Msun. Our findings of T-type sources (<0.004Msun) in the VISTA sigma Orionis exploration appear to be smaller than what is predicted by the extrapolation of the cluster mass spectrum down to the survey J-band completeness.Comment: Accepted for publication in ApJ. 69 pages, 15 figure

Multi-resolution anisotropy studies of ultrahigh-energy cosmic rays detected at the Pierre Auger Observatory

We report a multi-resolution search for anisotropies in the arrival directions of cosmic rays detected at the Pierre Auger Observatory with local zenith angles up to $80^\circ$ and energies in excess of 4 EeV ($4 \times 10^{18}$ eV). This search is conducted by measuring the angular power spectrum and performing a needlet wavelet analysis in two independent energy ranges. Both analyses are complementary since the angular power spectrum achieves a better performance in identifying large-scale patterns while the needlet wavelet analysis, considering the parameters used in this work, presents a higher efficiency in detecting smaller-scale anisotropies, potentially providing directional information on any observed anisotropies. No deviation from isotropy is observed on any angular scale in the energy range between 4 and 8 EeV. Above 8 EeV, an indication for a dipole moment is captured; while no other deviation from isotropy is observed for moments beyond the dipole one. The corresponding $p$-values obtained after accounting for searches blindly performed at several angular scales, are $1.3 \times 10^{-5}$ in the case of the angular power spectrum, and $2.5 \times 10^{-3}$ in the case of the needlet analysis. While these results are consistent with previous reports making use of the same data set, they provide extensions of the previous works through the thorough scans of the angular scales.Comment: Published version. Added journal reference and DOI. Added Report Numbe

Ultrahigh-energy neutrino follow-up of Gravitational Wave events GW150914 and GW151226 with the Pierre Auger Observatory

On September 14, 2015 the Advanced LIGO detectors observed their first gravitational-wave (GW) transient GW150914. This was followed by a second GW event observed on December 26, 2015. Both events were inferred to have arisen from the merger of black holes in binary systems. Such a system may emit neutrinos if there are magnetic fields and disk debris remaining from the formation of the two black holes. With the surface detector array of the Pierre Auger Observatory we can search for neutrinos with energy above 100 PeV from point-like sources across the sky with equatorial declination from about -65 deg. to +60 deg., and in particular from a fraction of the 90% confidence-level (CL) inferred positions in the sky of GW150914 and GW151226. A targeted search for highly-inclined extensive air showers, produced either by interactions of downward-going neutrinos of all flavors in the atmosphere or by the decays of tau leptons originating from tau-neutrino interactions in the Earth's crust (Earth-skimming neutrinos), yielded no candidates in the Auger data collected within $\pm 500$ s around or 1 day after the coordinated universal time (UTC) of GW150914 and GW151226, as well as in the same search periods relative to the UTC time of the GW candidate event LVT151012. From the non-observation we constrain the amount of energy radiated in ultrahigh-energy neutrinos from such remarkable events.Comment: Published version. Added journal reference and DOI. Added Report Numbe

Calibration of the Logarithmic-Periodic Dipole Antenna (LPDA) Radio Stations at the Pierre Auger Observatory using an Octocopter

An in-situ calibration of a logarithmic periodic dipole antenna with a frequency coverage of 30 MHz to 80 MHz is performed. Such antennas are part of a radio station system used for detection of cosmic ray induced air showers at the Engineering Radio Array of the Pierre Auger Observatory, the so-called Auger Engineering Radio Array (AERA). The directional and frequency characteristics of the broadband antenna are investigated using a remotely piloted aircraft (RPA) carrying a small transmitting antenna. The antenna sensitivity is described by the vector effective length relating the measured voltage with the electric-field components perpendicular to the incoming signal direction. The horizontal and meridional components are determined with an overall uncertainty of 7.4^{+0.9}_{-0.3} % and 10.3^{+2.8}_{-1.7} % respectively. The measurement is used to correct a simulated response of the frequency and directional response of the antenna. In addition, the influence of the ground conductivity and permittivity on the antenna response is simulated. Both have a negligible influence given the ground conditions measured at the detector site. The overall uncertainties of the vector effective length components result in an uncertainty of 8.8^{+2.1}_{-1.3} % in the square root of the energy fluence for incoming signal directions with zenith angles smaller than 60{\deg}.Comment: Published version. Updated online abstract only. Manuscript is unchanged with respect to v2. 39 pages, 15 figures, 2 table