The spectroscopic Hertzsprung-Russell diagram of Galactic massive stars

The distribution of stars in the Hertzsprung-Russell diagram narrates their evolutionary history and directly assesses their properties. Placing stars in this diagram however requires the knowledge of their distances and interstellar extinctions, which are often poorly known for Galactic stars. The spectroscopic Hertzsprung-Russell diagram (sHRD) tells similar evolutionary tales, but is independent of distance and extinction measurements. Based on spectroscopically derived effective temperatures and gravities of almost 600 stars, we derive for the first time the observational distribution of Galactic massive stars in the sHRD. While biases and statistical limitations in the data prevent detailed quantitative conclusions at this time, we see several clear qualitative trends. By comparing the observational sHRD with different state-of-the-art stellar evolutionary predictions, we conclude that convective core overshooting may be mass-dependent and, at high mass ($\geq 15\,M_\odot$), stronger than previously thought. Furthermore, we find evidence for an empirical upper limit in the sHRD for stars with $T_{\rm{eff}}$ between 10000 and 32000 K and, a strikingly large number of objects below this line. This over-density may be due to inflation expanding envelopes in massive main-sequence stars near the Eddington limit.Comment: 5 pages, 2 figures, 1 table; accepted for publication in A&A Letter

Pharmacogenetic Variation and Its Clinical Relevance in a Latin American Rural Population

Latin-American populations have been largely underrepresented in genomic studies of drug response and disease susceptibility. In this paper, we present a genome-wide Chilean dataset from Talca based on the Illumina Global Screening Array. This let us to compare the frequency of gene variants involved in response to drugs among our population and others, taking data from the 1000 Genomes Project. We found four single-nucleotide polymorphisms with low prevalence in Chileans when compared with African, Amerindian, East and South Asian, and European populations: rs2819742 (RYR2), rs2631367 (SLC22A5), rs1063320 (HLA-G), and rs1042522 (TP53). Moreover, two markers showed significant differences between lower and higher proportion of Mapuche ancestry groups: rs1719247 (located in an intergenic region in chromosome 15; p-value = 6.17 × 10-5, Bonferroni corrected p-value = 0.02) and rs738409 (A nonsynonymous gene variant in the PNPLA3 gene; p-value = 9.02 × 10-5, Bonferroni corrected p-value = 0.04). All of these polymorphisms have been shown to be associated with diverse pathologies, such as asthma, cancer, or chronic hepatitis B, or to be involved in a different response to drugs, such as metformin, HMG-CoA reductase inhibitors, or simvastatin. The present work provides a pharmacogenetic landscape of an understudied Latin American rural population and supports the notion that pharmacogenetic studies in admixed populations should consider ancestry for a higher accuracy of the results. Our study stresses the relevance of the pharmacogenomic research to provide guidance for a better choice of the best treatment for each individual in a population with admixed ancestry. Keywords: Chile; Latin-American; ancestry; personalized medicine; pharmacogenetics; single nucleotide polymorphism

Global design of analog cells using statistical optimization techniques

We present a methodology for automated sizing of analog cells using statistical optimization in a simulation based approach. This methodology enables us to design complex analog cells from scratch within reasonable CPU time. Three different specification types are covered: strong constraints on the electrical performance of the cells, weak constraints on this performance, and design objectives. A mathematical cost function is proposed and a bunch of heuristics is given to increase accuracy and reduce CPU time to minimize the cost function. A technique is also presented to yield designs with reduced variability in the performance parameters, under random variations of the transistor technological parameters. Several CMOS analog cells with complexity levels up to 48 transistors are designed for illustration. Measurements from fabricated prototypes demonstrate the suitability of the proposed methodology

The IACOB project. V. Spectroscopic parameters of the O-type stars in the modern grid of standards for spectral classification

The IACOB and OWN surveys are two ambitious complementary observational projects which have made available a large multi-epoch spectroscopic database of optical high resolution spectra of Galactic massive O-type stars. As a first step in the study of the full sample of (more than 350) O stars surveyed by the IACOB/OWN projects, we have performed the quantitative spectroscopic analysis of a subsample of 128 stars included in the modern grid of O-type standards for spectral classification. We use semi-automatized tools to determine the set of spectroscopic parameters that can be obtained from the optical spectrum of O-type stars. We also benefit from the multi-epoch character of the surveys to perform a spectroscopic variability study of the sample, accounting for spectroscopic binarity and variability of the main wind diagnostic lines. We provide a general overview of the stellar and wind parameters of this reference sample, and updated recipes for the SpT\,--\,Teff/log g calibrations for Galactic O-type stars. We evaluate our semi-automatized analysis strategy with $\sim$40 stars from the literature, and find a good agreement. The agreement between the synthetic spectra associated with fastwind best fitting models and the observed spectra is good for most targets, but 46 stars present a particular behavior of the wind diagnostic lines that cannot be reproduced by our grid of spherically symmetric unclumped models. These are potential targets of interest for more detailed investigations of clumpy winds and/or the existence of additional circumstellar components. Last, our variability study has led to the detection of signatures of spectroscopic binarity in 27\% of the stars and small amplitude radial velocity variations in the photospheric lines of another 30\%. Additionally, 31\% of the investigated stars show variability in the wind diagnostic lines.Comment: 20 pages, 18 figures, accepted for publication in Astronomy & Astrophysic

The IACOB project. VI. On the elusive detection of massive O-type stars close to the ZAMS

The apparent lack of massive O-type stars near the zero-age main sequence (at ages < 2 Myr) is a topic widely discussed. Different explanations for this elusive detection have been proposed, but no firm conclusions have been reached yet. We reassess this empirical result benefiting from the high-quality spectroscopic observations of >400 Galactic O-type stars gathered by the IACOB and OWN surveys. We used temperatures and gravities from a iacob-gbat/fastwind spectroscopic analysis to locate our sample in the Kiel and spectroscopic HR diagrams. We evaluated the completeness of our sample of stars, observational biases using information from the Galactic O star catalog (GOSC), systematics of our methodology, and compare with other recent studies using smaller samples of Galactic O-type stars. We base our discussion on the spectroscopic HR diagram to avoid the use of uncertain distances. We performed a detailed study of the young cluster Trumpler-14 as an example of how Gaia cluster distances can help to construct the associated classical HR diagram. The apparent lack of massive O-type stars near the ZAMS with masses between 30 and 70 Msol persist even when spectroscopic results from a large, non-biased sample of stars are used. We do not find correlation between the dearth of stars and observational biases, limitations of our methodology, or the use of spectroscopic HR diagram instead of the classical one. Investigating the efficiency of mass accretion during the formation process we conclude that an adjustment of the accretion rate towards lower values could reconcile the hotter boundary of detected O-type stars and the theoretical birthline. Last, we discuss that the presence of a small sample of O2-O3.5 stars found closer to the ZAMS might be explained taking into account non-standard star evolution (e.g. binary interaction, mergers, or homogeneous evolution).Comment: 20 pages, 15 figures, accepted for publication in Astronomy & Astrophysic

Annual Legumes as an Alternative for Animal Feeding in Cuba

Studies conducted in Cuba have demonstrated the importance of the agronomic and nutritional performance of the species Vigna unguiculata (cowpea), Canavalia ensiformis (jackbean), Stizolobium niveum (mucuna), Lablab purpureus (dolicho) and Glycine max (soybean) as feed sources for non-ruminant species. Under Cuban tropical conditions, and with minimum agricultural inputs, jackbean, dolicho and mucuna have attained forage yields between 4 and 6 t dry matter (DM)/ha and grain yields between 2.57 and 3.41 t/ha and cowpea and soybean have given yields of between 1 and 2 t/ha (Díaz 2000). This study was carried out to determine the chemical composition of grains and forages of these annual legumes in relation to their use in animal feeding

QoSatAr: a cross-layer architecture for E2E QoS provisioning over DVB-S2 broadband satellite systems

This article presents QoSatAr, a cross-layer architecture developed to provide end-to-end quality of service (QoS) guarantees for Internet protocol (IP) traffic over the Digital Video Broadcasting-Second generation (DVB-S2) satellite systems. The architecture design is based on a cross-layer optimization between the physical layer and the network layer to provide QoS provisioning based on the bandwidth availability present in the DVB-S2 satellite channel. Our design is developed at the satellite-independent layers, being in compliance with the ETSI-BSM-QoS standards. The architecture is set up inside the gateway, it includes a Re-Queuing Mechanism (RQM) to enhance the goodput of the EF and AF traffic classes and an adaptive IP scheduler to guarantee the high-priority traffic classes taking into account the channel conditions affected by rain events. One of the most important aspect of the architecture design is that QoSatAr is able to guarantee the QoS requirements for specific traffic flows considering a single parameter: the bandwidth availability which is set at the physical layer (considering adaptive code and modulation adaptation) and sent to the network layer by means of a cross-layer optimization. The architecture has been evaluated using the NS-2 simulator. In this article, we present evaluation metrics, extensive simulations results and conclusions about the performance of the proposed QoSatAr when it is evaluated over a DVB-S2 satellite scenario. The key results show that the implementation of this architecture enables to keep control of the satellite system load while guaranteeing the QoS levels for the high-priority traffic classes even when bandwidth variations due to rain events are experienced. Moreover, using the RQM mechanism the user’s quality of experience is improved while keeping lower delay and jitter values for the high-priority traffic classes. In particular, the AF goodput is enhanced around 33% over the drop tail scheme (on average)

Propagación clonal in vitro de arboles elite de teca (tectona grandis l.)

EI empleo de las técnicas de cultivo de tejidos vegetales para la propagación y el mejoramiento de especies de interés forestal es una importante herramienta de apoyo a los programas de reforestación y establecimiento de huertos semilleros clonales. EI objetivo del presente trabajo consistió en el desarrollo de una metodología para la propagación clonal in vitro de la teca a partir de arboles elite. Como fuente de explantes se emplearon ápices procedentes de brotes epicormicos, los cuales se sembraron en el medio de cultivo de Schenk y Hildebrandt, enriquecido con los microelementos de Bourgin y Nitsch, Bencil Amino Purina (BAP 0,5 mg/L) y solidificado con agar. Para la fase de proliferación se empleó el medio de cultivo de Murashige y Skoog con las sales nitrogenadas reducidas a la mitad de su concentración normal. Se evaluaron diferentes concentraciones de BAP (0, 0,1, 0,5 Y 1,0 mg/L). EI mayor coeficiente de multiplicaci6n y mejor calidad de los brotes se logr6 con 0,5 mg/L de BAP.  El enraizamiento se realizó en condiciones ex vitro; se emplearon microesquejes apicales con una longitud pro media de 1,5 a 2,0 cm. Estos se trataron con diferentes concentraciones de AlB (0,250, 500, 1.000, 2.000, 4.000 Y5.000 mg/L), Los mayores porcentajes de enraizamiento y supervivencia de las plantulas se lograron con 4.000 mg/L de AlB. Esta metodología permitió el establecimiento de los arboles en condiciones de campo para apoyar los programas de huertos semilleros clonales y plantaciones a escala comercial de Refocosta.The employment of the techniques of plant tissue culture for the propagation and the genetic improvement of forest trees are importants support tool to the reforestation programs and the establishment of clonal seed orchards. This work's main objective was the development of a methodology for the in vitro clonal propagation of teak, starting from elite trees. As explants source apical shoots from epicormic buds were used, which were placed in the basal medium of Schenk and Hildebrandt supplemented with 0.5 mg/L of BAr, Bourgin and Nitsch micronutrients and solidified with agar. For the proliferation phase it was used the basal medium of Murashige and Skoog with half of the normal NH4N03 and KN03 concentration. Different concentrations of BAP were evaluated (0, 0,1, 0,5 and 1,0 mg/L). The biggest multiplication coefficient and better quality of the buds was achieved with 0.5 mg/L of BAP. The rooting was carried out under ex vitro conditions; were used microcutings between 1.5 and 2.0 em of length. Then, they were treated with different concentrations of IBA (0, 250, 500, 1.000, 2.000, 4.000 and 5.000 mg/L). The biggest rooting percentage and plantlets survival was achieved with 4000 mg/L of IBA. This methodology allowed the establishment of the trees under field conditions to support the programs of clonal seed orchards and operative plantations of Refocosta