1,051 research outputs found
Lithium in the Hyades L5 brown dwarf 2MASS J04183483+2131275
Aims. From the luminosity, effective temperature and age of the Hyades brown dwarf 2MASS J04183483+2131275 (2M0418), substellar evolutionary models predict a mass in the range 39−55 Jupiter masses (MJup) which is insufficient to produce any substantial lithium burning except for the very upper range >53 MJup. Our goal is to measure the abundance of lithium in this object, test the consistency between models and observations and refine constraints on the mass and age of the object.
Methods. We used the 10.4-m Gran Telescopio Canarias (GTC) with its low-dispersion optical spectrograph to obtain ten spectra of 2277 s each covering the range 6300–10 300 Å with a resolving power of R ~ 500.
Results. In the individual spectra, which span several months, we detect persistent unresolved Hα in emission with pseudo equivalent widths (pEW) in the range 45–150 Å and absorption lines of various alkalis with the typical strengths found in objects of L5 spectral type. The lithium resonance line at 6707.8 Å is detected with pEW of 18 ± 4 Å in 2M0418 (L5).
Conclusions. We determine a lithium abundance of log N(Li) = 3.0 ± 0.4 dex consistent with a minimum preservation of 90% of this element which confirms 2M0418 as a brown dwarf with a maximum mass of 52 MJup. We infer a maximum age for the Hyades of 775 Myr from a comparison with the BHAC15 models. Combining recent results from the literature with our study, we constrain the mass of 2M0418 to 45–52 MJup and the age of the cluster to 580–775 Myr (1σ) based on the lithium depletion boundary method.We thank the referee for a detailed report that improved the
quality of this manuscript. This research has been supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under the grants AYA2015-
69350-C3-2-P and AYA2015-69350-C3-3-P. We thank Yakiv Pavlenko for his
calculations of equivalent widths at different temperatures, Isabelle Baraffe for
her models, and Eduardo Martín for sharing his results prior to publication. This
work is based on observations made with the Gran Telescopio Canarias (GTC),
operated on the island of La Palma in the Spanish Observatorio del Roque de
los Muchachos of the Instituto de Astrofísica de Canarias (programme GTC77-
16B led by Pérez Garrido). This research has made use of the Simbad and
Vizier databases, operated at the Centre de Données Astronomiques de Strasbourg (CDS), and of NASA’s Astrophysics Data System Bibliographic Services
(ADS). We thank John Stauffer for kindly providing the optical spectra of the K
and M Hyades members published in 1997 (Stauffer et al. 1997a)
Wastewater Treatment by Advanced Oxidation Process and Their Worldwide Research Trends
Background: Water is a scarce resource and is considered a fundamental pillar of sustainable development. The modern development of society requires more and more drinking water. For this cleaner wastewater, treatments are key factors. Among those that exist, advanced oxidation processes are being researched as one of the sustainable solutions. The main objective of this manuscript is to show the scientific advances in this field. Methods: In this paper, a systematic analysis of all the existing scientific works was carried out to verify the evolution of this line of research. Results: It was observed that the three main countries researching this field are China, Spain, and the USA. Regarding the scientific collaboration between countries, three clusters were detected—one of Spain, one of China and the USA, and one of Italy and France. The publications are grouped around three types of water: industrial, urban, and drinking. Regarding the research, 15 clusters identified from the keywords analyzed the advanced oxidation process (alone or combined with biological oxidation) with the type of wastewater and the target pollutant, removal of which is intended. Finally, the most important scientific communities or clusters detected in terms of the number of published articles were those related to the elimination of pollutants of biological origin, such as bacteria, and of industrial nature, such as pesticides or pharmaceutical products
Libros, manuscritos y plantas secas de Mariano La Gasca (1776-1839) conservados actualmente en Málaga
Material botánico de Mariano La Gasca (1776-1839)
llegado a Málaga en 1834, desde Inglaterra, que acompañaba a su propietario en
el exilio y que aún permanece en Málaga –en
diferente ubicación–. Consiste en una gran
parte de su biblioteca (unos 250 volúmenes),
un número considerable de apuntes científicos,
correspondencia personal y plantas secas.
Podemos describir aquí ese “legado
malagueño” gracias al profesor Antonio
Acosta (1924−2004), quién nos informó de la
catalogación previa del bibliotecario F. Báguena
(1958)1 y nos cedió los manuscritos originales
y plantas secas de La Gasca que custodiaba
Tunneling time and Faraday/Kerr effects in -symmetric systems
We review the generalization of tunneling time and anomalous behaviour of
Faraday and Kerr rotation angles in parity and time
()-symmetric systems. Similarities of two phenomena are
discussed, both exhibit a phase transition-like anomalous behaviour in certain
range of model parameters. Anomalous behaviour of tunneling time and
Faraday/Kerr angles in -symmetric systems is caused by
the motion of poles of scattering amplitudes in energy/frequency complex plane.Comment: Match to accepted version, Invited EPL perspective review. arXiv
admin note: text overlap with arXiv:2208.1354
Removal of emerging pollutants in conventional and microalgae based biotechnology urban wastewater treatment plants
Wastewater treatment plants (WWTPs) reduce portion of the input of pharmaceuticals in aquatic systems, but there is no data available about the elimination of emerging contaminants with microalgae technology. The aim of this work was to determine the average mass flows and concentrations of pharmaceuticals in influents and effluents from two sewages treatment plants using conventional and microalgae based biotechnologies and to compare the removal of pharmaceuticals using both depuration technologies. Only between 20 to 60% of five pharmaceuticals groups is reduce in both WWTP using conventional technologies consisting of a pretreatment, primary settling and secondary treatment by aerobic biological reactor. Using microalgae based biotechnologies efficiency of removal pharmaceuticals is higher than conventional technologies and it increase by using DAF (Dissolve Air Flotation) technology to separate algae biomass
Relaciones entre la práctica física, condición física y atención en una muestra adolescente
El propósito de este trabajo fue examinar las relaciones entre la práctica de actividad física, la condición física y la atención en un grupo de adolescentes. Participaron en el estudio 149 adolescentes de la provincia de Málaga (España), con edades entre 14 y 16 años (M = 15.05; DE = .77). Para analizar los procesos atencionales se utilizó el test d2. La condición física se evaluó a través del test de salto horizontal, el test de Course Navette y el test de velocidad 5 x 10 metros. Los análisis indicaron mayores puntuaciones en diversos parámetros del test d2 en aquellos participantes que realizaban actividad física regularmente, así como relaciones significativas entre las medidas de condición física y las pruebas de atención, siendo el consumo de oxígeno la variable más relevante. Los resultados hallados apoyan la importancia de practicar actividad física en la infancia y la adolescencia, sugiriendo que el incremento de la condición física puede tener implicaciones positiva sobre la atención en estas edades.The purpose of this study was to examine the relationship between physical activity, fitness and attention in a group of adolescents. 149 adolescents aged between 14 and 16 years old (M = 15.05; SD = .77) took part in the study. The D-2 Test was used to analyse attention processes. Physical fitness was assessed with the horizontal jump test, the Course Navette test and the 5 x 10 metre sprint test. Analyses indicated higher scores on some measures of the D-2 test in participants who regularly did sports and significant relationships between fitness tests and measurements of attention, with oxygen consumption being the most relevant variable. The results obtained support the importance of physical activity in childhood and adolescence, suggesting that increased fitness may have positive implications on attention at this age.O propósito deste trabalho foi analisar as relações entre a prática de actividade física, a condição física e a atenção num grupo de adolescentes. Participaram no estudo 149 adolescentes da província de Málaga (Espanha), com idades compreendidas entre os 14 e os 16 anos (M = 15.05; DP = .77). Para analisar os processos atencionais foi utilizado o teste d2. A condição física foi avaliada através do teste de salto horizontal, o teste de Course Navette e o teste de velocidade 5 x 10 metros. As análises indicaram pontuações mais elevadas nos diversos parâmetros do teste d2 para os participantes que realizavam actividade física regularmente, assim como relações significativas entre as medidas de condição física e as provas de atenção, sendo o consumo de oxigénio a variável mais relevante. Os resultados encontrados suportam a importância de praticar actividade física na infância e adolescência, sugerindo que o incremento da condição física pode ter implicações positivas na atenção nestas idades
Post-Newtonian limit: second-order Jefimenko equations
The purpose of this paper is to get second-order
gravitational equations, a correction made to Jefimenko’s
linear gravitational equations. These linear equations were
first proposed by Oliver Heaviside in [1], making an analogy
between the laws of electromagnetism and gravitation. To
achieve our goal, we will use perturbation methods on Einstein field equations. It should be emphasized that the resulting system of equations can also be derived from Logunov’s
non-linear gravitational equations, but with different physical
interpretation, for while in the former gravitation is considered as a deformation of space-time as we can see in [2–5], in the latter gravitation is considered as a physical tensor field
in the Minkowski space-time (as in [6–8]). In Jefimenko’s
theory of gravitation, exposed in [9,10], there are two kinds
of gravitational fields, the ordinary gravitational field, due
to the presence of masses, at rest, or in motion and other
field called Heaviside field due to and acts only on moving
masses. The Heaviside field is known in general relativity as
Lense-Thirring effect or gravitomagnetism (The Heaviside
field is the gravitational analogous of the magnetic field in the
electromagnetic theory, its existence was proved employing
the Gravity Probe B launched by NASA (See, for example,
[11,12]). It is a type of gravitational induction), interpreted
as a distortion of space-time due to the motion of mass distributions, (see, for example [13,14]). Here, we will present our second-order Jefimenko equations for gravitation and its solutions
Congruency fit: beyond performance in the auto supplier industry
The effects of manufacturing strategy (MS) and technology (T) on performance have been
studied separately, but few studies have examined the relationship between MS and T practices
clusters that improve effectiveness when implemented jointly, and even then they do not
consider possible congruency between the two. This paper develops a congruency (selection)
model to test for any interconnection between said clusters, without addressing causation or their
combined effect on performance. The implicit outcome is that the plant will achieve a desirable
effectiveness level. Through a wide-ranging survey of auto supplier plants, two approaches are
considered: 1) grouping both clusters in pairs (canonical correlation analysis); and 2) a more
general selection view version, with practices from both clusters related multidimensionally and
subordinated by bivariate analysis (regression) to test for any congruent pattern. Both methods
find a congruent relationship between manufacturing strategy and technology practice clusters,
although the second provides greater detail.Ministerio de Educación y Ciencia DPI-2006-0553
The potential of different marine microalgae species to recycle nutrients from recirculating aquaculture systems (RAS) fish farms and produce feed additives
This study researched the use of six microalgae species (N. gaditana, P. lutheri, I. galbana, T. chuii, P. tricornutum and C. gracilis) and a bloom to treat effluent from a marine fish farm and produce quality biomass. More specifically, simulated water from a recirculating aquaculture system (RAS) was used. Microalgae culture was carried out under controlled conditions using 18 L bubble column photoreactors under batch and semi-continuous operation. The main parameters analysed were micronutritional requirements, biomass productivity, nutrient removal rate (nitrogen and phosphorus), biomass composition, and quality. Also, based on the results obtained, a quantitative classification of the microalgae was carried out. The results showed that all microalgae required at least trace metals. In certain species, the addition of vitamins was also required for viable cultivation. In the case of biomass productivity under batch operation, values were between 67 mg L−1 d−1 and 7 mg L−1 d−1 using T. chuii and C. gracilis, respectively, and between 71 mg L−1 d−1 and 9 mg L−1 d−1 using T. chuii and N. gaditana under semi-continuous operation. In the case of total dissolved phosphorus removal, no differences were found between species, reaching in all cases final concentrations <0.01 mg L−1. Total dissolved nitrogen removal rate varied between species and operating conditions, being the highest obtained using T. chuii under semi-continuous operation (12.6 mg L−1 d−1) and the lowest with C. gracilis batch operation (0.15 mg L−1 d−1). Biomass composition in terms of protein and lipids varied between species and operating conditions, but quality in terms of amino acids and fatty acids profile remained homogeneous in all cases. Finally, according to the developed score methodology, I. galbana was the microalgae with the highest biomass production score, while T. chuii was for wastewater treatment. © 2021This work was carried out within the SUNRAS Project ?Sustainable and Efficient Management of Marine Aquaculture Effluents using Solar Technologies? (N? AGL2016-80507-R; Plan Nacional de I+D+i 2013?2016) funded by Ministry of Economy and Competitiveness, Government of Spain. This study was also supported by a Personal Investigador en Formaci?n (PIF) contract (Ref. UCA/REC01VI/2017) funded by Universidad de C?diz. We also would like to acknowledge the technicians of Servicio Central de Investigaci?n en Cultivos Marinos at the Faculty of Marine and Environmental Science (Universidad de C?diz) and Centro Tecnol?gico de Acuicultura de Andaluc?a (CTAQUA) for their support
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