55 research outputs found
Expected spectral characteristics of (101955) Bennu and (162173) Ryugu, targets of the OSIRIS-REx and Hayabusa2 missions
NASA's OSIRIS-REx and JAXA's Hayabusa2 sample-return missions are currently
on their way to encounter primitive near-Earth asteroids (101955) Bennu and
(162173) Ryugu, respectively. Spectral and dynamical evidence indicates that
these near-Earth asteroids originated in the inner part of the main belt. There
are several primitive collisional families in this region, and both these
asteroids are most likely to have originated in the Polana-Eulalia family
complex. We present the expected spectral characteristics of both targets based
on our studies of our primitive collisional families in the inner belt:
Polana-Eulalia, Erigone, Sulamitis, and Clarissa. Observations were obtained in
the framework of our PRIMitive Asteroids Spectroscopic Survey (PRIMASS). Our
results are especially relevant to the planning and interpretation of in-situ
images and spectra to be obtained by the two spacecraft during the encounters
with their targets.Comment: 22 pages, 11 figures. Accepted for publication in Icarus on May 11,
201
Near-Earth asteroids spectroscopic survey at Isaac Newton Telescope
The population of near-Earth asteroids (NEAs) shows a large variety of
objects in terms of physical and dynamical properties. They are subject to
planetary encounters and to strong solar wind and radiation effects. Their
study is also motivated by practical reasons regarding space exploration and
long-term probability of impact with the Earth. We aim to spectrally
characterize a significant sample of NEAs with sizes in the range of 0.25
- 5.5 km (categorized as large), and search for connections between their
spectral types and the orbital parameters. Optical spectra of NEAs were
obtained using the Isaac Newton Telescope (INT) equipped with the IDS
spectrograph. These observations are analyzed using taxonomic classification
and by comparison with laboratory spectra of meteorites. A total number of 76
NEAs were observed. We classified 44 of them as Q/S-complex, 16 as B/C-complex,
eight as V-types, and another eight belong to the remaining taxonomic classes.
Our sample contains 27 asteroids categorized as potentially hazardous and 31
possible targets for space missions including (459872) 2014 EK24, (436724) 2011
UW158, and (67367) 2000 LY27. The spectral data corresponding to (276049) 2002
CE26 and (385186) 1994 AW1 shows the 0.7 m feature which indicates the
presence of hydrated minerals on their surface. We report that Q-types have the
lowest perihelia (a median value and absolute deviation of AU)
and are systematically larger than the S-type asteroids observed in our sample.
We explain these observational evidences by thermal fatigue fragmentation as
the main process for the rejuvenation of NEA surfaces. In general terms, the
taxonomic distribution of our sample is similar to the previous studies and
matches the broad groups of the inner main belt asteroids. Nevertheless, we
found a wide diversity of spectra compared to the standard taxonomic types.Comment: Accepted in Astronomy & Astrophysics (A&A
Utilização de fontes de energia renováveis para o aquecimento de aves.
Projeto/Plano de Ação: 03.05.01.021
DNA damage in children and adolescents with cardiovascular disease risk factors
The risk of developing cardiovascular disease (CVD) is related to lifestyle (e.g. diet, physical activity and smoking) as well as to genetic factors. This study aimed at evaluating the association between CVD risk factors and DNA damage levels in children and adolescents. Anthropometry, diet and serum CVD risk factors were evaluated by standard procedures. DNA damage levels were accessed by the comet assay (Single cell gel electrophoresis; SCGE) and cytokinesis-blocked micronucleus (CBMN) assays in leukocytes. A total of 34 children and adolescents selected from a population sample were divided into three groups according to their level of CVD risk. Moderate and high CVD risk subjects showed significantly higher body fat and serum CVD risk markers than low risk subjects (PO risco de desenvolver doença cardiovascular (DCV) está relacionado ao estilo de vida (por exemplo, dieta, atividade física e tabagismo), bem como a fatores genéticos. Este estudo teve como objetivo avaliar a associação entre fatores de risco cardiovascular e os níveis de danos ao DNA em crianças e adolescentes. Antropometria, dieta e fatores de risco para DCV foram avaliados através de procedimentos padrão. Níveis de danos no DNA foram avaliados através do ensaio cometa (eletroforese de célula única; EC) e do teste de micronúcleos em leucócitos. Um total de 34 crianças e adolescentes, selecionados a partir de uma amostra populacional, foram divididos em três grupos, de acordo com seu nível de risco de DCV. Indivíduos com níveis moderado e alto risco para DCV apresentaram de forma significativa maiores níveis de gordura corporal e de marcadores séricos de risco cardiovascular que indivíduos de baixo risco (P <0,05). Indivíduos de alto risco também mostraram um aumento significativo de danos ao DNA, de acordo com o EC, mas não de acordo com o teste de micronúcleos, do que indivíduos de risco baixo e moderado. A vitamina C consumida foi inversamente correlacionada com os danos ao DNA avaliados pelo EC, e o número de micronúcleos foi inversamente correlacionado com a ingestão de ácido fólico. Os resultados obtidos indicam um aumento de danos no DNA que pode ser consequente do estresse oxidativo em indivíduos jovens com fatores de risco para DCV, indicando que o nível de danos no DNA pode auxiliar na avaliação do risco de DCV
Studies of micronuclei and other nuclear abnormalities in red blood cells of Colossoma macropomum exposed to methylmercury
The frequencies of micronuclei (MN) and morphological nuclear abnormalities (NA) in erythrocytes in the peripheral blood of tambaqui (Colossoma macropomum), treated with 2 mg.L−1 methylmercury (MeHg), were analyzed. Two groups (nine specimens in each) were exposed to MeHg for different periods (group A - 24 h; group B - 120 h). A third group served as negative control (group C, untreated; n = 9). Although, when compared to the control group there were no significant differences in MN frequency in the treated groups, for NA, the differences between the frequencies of group B (treated for 120 h) and the control group were extremely significant (p < 0.02), thus demonstrating the potentially adverse effects of MeHg on C. macropomum erythrocytes after prolonged exposure
J-PLUS: The javalambre photometric local universe survey
ABSTRACT: TheJavalambrePhotometric Local UniverseSurvey (J-PLUS )isanongoing 12-band photometricopticalsurvey, observingthousands of squaredegrees of theNorthernHemispherefromthededicated JAST/T80 telescope at the Observatorio Astrofísico de Javalambre (OAJ). The T80Cam is a camera with a field of view of 2 deg2 mountedon a telescopewith a diameter of 83 cm, and isequippedwith a uniquesystem of filtersspanningtheentireopticalrange (3500–10 000 Å). Thisfiltersystemis a combination of broad-, medium-, and narrow-band filters, optimallydesigned to extracttherest-framespectralfeatures (the 3700–4000 Å Balmer break region, Hδ, Ca H+K, the G band, and the Mg b and Ca triplets) that are key to characterizingstellartypes and delivering a low-resolutionphotospectrumforeach pixel of theobservedsky. With a typicaldepth of AB ∼21.25 mag per band, thisfilter set thusallowsforanunbiased and accuratecharacterization of thestellarpopulation in our Galaxy, itprovidesanunprecedented 2D photospectralinformationforall resolved galaxies in the local Universe, as well as accuratephoto-z estimates (at the δ z/(1 + z)∼0.005–0.03 precisionlevel) formoderatelybright (up to r ∼ 20 mag) extragalacticsources. Whilesomenarrow-band filters are designedforthestudy of particular emissionfeatures ([O II]/λ3727, Hα/λ6563) up to z < 0.017, theyalsoprovidewell-definedwindowsfortheanalysis of otheremissionlines at higherredshifts. As a result, J-PLUS has thepotential to contribute to a widerange of fields in Astrophysics, both in thenearbyUniverse (MilkyWaystructure, globular clusters, 2D IFU-likestudies, stellarpopulations of nearby and moderate-redshiftgalaxies, clusters of galaxies) and at highredshifts (emission-line galaxies at z ≈ 0.77, 2.2, and 4.4, quasi-stellarobjects, etc.). Withthispaper, wereleasethefirst∼1000 deg2 of J-PLUS data, containingabout 4.3 millionstars and 3.0 milliongalaxies at r < 21mag. With a goal of 8500 deg2 forthe total J-PLUS footprint, thesenumbers are expected to rise to about 35 millionstars and 24 milliongalaxiesbytheend of thesurvey.Funding for the J-PLUS Project has been provided by the Governments of Spain and Aragón through the Fondo de Inversiones de Teruel, the Spanish Ministry of Economy and Competitiveness (MINECO; under grants AYA2017-86274-P, AYA2016-77846-P, AYA2016-77237-C3-1-P, AYA2015-66211-C2-1-P, AYA2015-66211-C2-2, AYA2012-30789, AGAUR grant SGR-661/2017, and ICTS-2009-14), and European FEDER funding (FCDD10-4E-867, FCDD13-4E-2685
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