508 research outputs found
Units of relativistic time scales and associated quantities
This note suggests nomenclature for dealing with the units of various
astronomical quantities that are used with the relativistic time scales TT,
TDB, TCB and TCG. It is suggested to avoid wordings like "TDB units" and "TT
units" and avoid contrasting them to "SI units". The quantities intended for
use with TCG, TCB, TT or TDB should be called "TCG-compatible",
"TCB-compatible", "TT-compatible" or "TDB-compatible", respectively. The names
of the units second and meter for numerical values of all these quantities
should be used with out any adjectives. This suggestion comes from a special
discussion forum created within IAU Commission 52 "Relativity in Fundamental
Astronomy"
Aquatic pollution may favor the success of the invasive species A. franciscana
The genus Artemia consists of several bisexual and parthenogenetic sibling species. One of them, A. franciscana, originally restricted to the New World, becomes invasive when introduced into ecosystems out of its natural range of distribution. Invasiveness is anthropically favored by the use of cryptobiotic eggs in the aquaculture and pet trade. The mechanisms of out-competition of the autochthonous Artemia by the invader are still poorly understood. Ecological fitness may play a pivotal role, but other underlying biotic and abiotic factors may contribute. Since the presence of toxicants in hypersaline aquatic ecosystems has been documented, our aim here is to study the potential role of an organophosphate pesticide, chlorpyrifos, in a congeneric mechanism of competition between the bisexual A. franciscana (AF), and one of the Old World parthenogenetic siblings, A. parthenogenetica (PD). For this purpose we carried out life table experiments with both species, under different concentrations of the toxicant (0.1, 1 and 5. μg/l), and analyzed the cholinesterase inhibition at different developmental stages. The results evidence that both, AF and PD, showed an elevated tolerance to high ranges of chlorpyrifos, but AF survived better and its fecundity was less affected by the exposure to the pesticide than that of PD. The higher fecundity of AF is a selective advantage in colonization processes leading to its establishment as NIS. Besides, under the potential selective pressure of abiotic factors, such as the presence of toxicants, its higher resistance in terms of survival and biological fitness also indicates out-competitive advantages. © 2015This research was supported by the Spanish Ministry for Science and Innovation projects (CGL2005-02306 and CGL2008-04737-E) “Biodiversidad de Artemia (Branchiopoda, Anostraca) en el Mediterráneo Occidental, archipiélagos Balear y Canario. Efectos de A. franciscana como especie invasora. Implicaciones ecológicas y de interés en acuicultura” y “Biodiversidad amenazada en salinas mediterráneas”. S. Redón was supported by a Ph.D grant (FPI) from the Spanish Ministry of Science and Innovation. D. Guinot was supported by BANCAJA contract.Peer Reviewe
Aquatic pollution may favor the success of the invasive species A. franciscana
The genus Artemia consists of several bisexual and parthenogenetic sibling species. One of them, A. franciscana, originally restricted to the New World, becomes invasive when introduced into ecosystems out of its natural range of distribution. Invasiveness is anthropically favored by the use of cryptobiotic eggs in the aquaculture and pet trade. The mechanisms of out-competition of the autochthonous Artemia by the invader are still poorly understood. Ecological fitness may play a pivotal role, but other underlying biotic and abiotic factors may contribute. Since the presence of toxicants in hypersaline aquatic ecosystems has been documented, our aim here is to study the potential role of an organophosphate pesticide, chlorpyrifos, in a congeneric mechanism of competition between the bisexual A. franciscana (AF), and one of the Old World parthenogenetic siblings, A. parthenogenetica (PD). For this purpose we carried out life table experiments with both species, under different concentrations of the toxicant (0.1, 1 and 5 μg/l), and analyzed the cholinesterase inhibition at different developmental stages. The results evidence that both, AF and PD, showed an elevated tolerance to high ranges of chlorpyrifos, but AF survived better and its fecundity was less affected by the exposure to the pesticide than that of PD. The higher fecundity of AF is a selective advantage in colonization processes leading to its establishment as NIS. Besides, under the potential selective pressure of abiotic factors, such as the presence of toxicants, its higher resistance in terms of survival and biological fitness also indicates out-competitive advantages.Spanish Ministry for Science and Innovation project, CGL2005-02306, CGL2008-04737-E
"Ethnic disparities in the prevalence of Molar-Incisor-Hypomineralisation (MIH) and caries among 6-12-year-old children in Catalonia, Spain"
AIM: To study the prevalence of MIH and caries in 6- and 12-year-old schoolchildren and their association with ethnic disparities and other relevant factors. BACKGROUND: In recent years, there has been uneven improvement in school children's oral health, highlighting inequalities in access to dental care and health outcomes, particularly among ethnic minorities. The most prevalent oral disease in childhood, caries, is preventable, as its risk factors are well known. However, MIH, a common condition affecting the enamel of permanent incisors and/or molars, has no established aetiology or preventive measures. METHODS: A cross-sectional study among schoolchildren was conducted in 725 children from Masnou (Barcelona, 2013) and in 577 children from Sant Andreu de Llavaneres (Barcelona, 2018-2020). Data collection was carried out by means of clinical examination and a selfreferenced questionnaire. Oral health outcomes included: presence of dental caries, presence of MIH, hypomineralised second primary molars (HSPM). All variables were analysed according to ethnic disparities and other variables such as socioeconomics, diet, hygiene habits, plaque and access to dental services. We performed multivariate Poisson regression models with robust variance to examine ethnic disparities in MIH and caries. CONCLUSION: This cross-sectional study based in Catalonia, Spain showed that there are ethnic disparities in caries as observed with other child's diseases; however, they do not seem to follow the same pattern for MIH. More studies are needed (i) to explore how MIH behaves among populations in terms of inequality; (ii) to study the aetiological factors of MIH; and (iii) to identify potential factors associated with MIH and caries that have not been studied and that may contribute to the observed ethnic disparities.</p
"Ethnic disparities in the prevalence of Molar-Incisor-Hypomineralisation (MIH) and caries among 6-12-year-old children in Catalonia, Spain"
AIM: To study the prevalence of MIH and caries in 6- and 12-year-old schoolchildren and their association with ethnic disparities and other relevant factors. BACKGROUND: In recent years, there has been uneven improvement in school children's oral health, highlighting inequalities in access to dental care and health outcomes, particularly among ethnic minorities. The most prevalent oral disease in childhood, caries, is preventable, as its risk factors are well known. However, MIH, a common condition affecting the enamel of permanent incisors and/or molars, has no established aetiology or preventive measures. METHODS: A cross-sectional study among schoolchildren was conducted in 725 children from Masnou (Barcelona, 2013) and in 577 children from Sant Andreu de Llavaneres (Barcelona, 2018-2020). Data collection was carried out by means of clinical examination and a selfreferenced questionnaire. Oral health outcomes included: presence of dental caries, presence of MIH, hypomineralised second primary molars (HSPM). All variables were analysed according to ethnic disparities and other variables such as socioeconomics, diet, hygiene habits, plaque and access to dental services. We performed multivariate Poisson regression models with robust variance to examine ethnic disparities in MIH and caries. CONCLUSION: This cross-sectional study based in Catalonia, Spain showed that there are ethnic disparities in caries as observed with other child's diseases; however, they do not seem to follow the same pattern for MIH. More studies are needed (i) to explore how MIH behaves among populations in terms of inequality; (ii) to study the aetiological factors of MIH; and (iii) to identify potential factors associated with MIH and caries that have not been studied and that may contribute to the observed ethnic disparities.</p
One blind and three targeted searches for (sub)millisecond pulsars
We conducted one blind and three targeted searches for millisecond and
submillisecond pulsars. The blind search was conducted within 3deg of the
Galactic plane and at longitudes between 20 and 110deg. It takes 22073
pointings to cover this region, and 5487 different positions in the sky. The
first targeted search was aimed at Galactic globular clusters, the second one
at 24 bright polarized and pointlike radiosources with steep spectra, and the
third at 65 faint polarized and pointlike radiosources. The observations were
conducted at the large radiotelescope of Nancay Observatory, at a frequency
near 1400 MHz. Two successive backends were used, first a VLBI S2 system,
second a digital acquisition board and a PC with large storage capacity
sampling the signal at 50 Mb/s on one bit, over a 24-MHz band and in one
polarization. The bandwidth of acquisition of the second backend was later
increased to 48 MHz and the sampling rate to 100 Mb/s. The survey used the
three successive setups, with respective sensitivities of 3.5, 2.2, and 1.7
mJy. The targeted-search data were obtained with the third setup and reduced
with a method based on the Hough transform, yielding a sensitivity of 0.9 mJy.
The processing of the data was done in slightly differed time by
soft-correlation in all cases. No new short-period millisecond pulsars were
discovered in the different searches. To better understand the null result of
the blind survey, we estimate the probability of detecting one or more
short-period pulsars among a given Galactic population of synthetic pulsars
with our setup: 25% for the actual incomplete survey and 79% if we had
completed the whole survey with a uniform nominal sensitivity of 1.7 mJy. The
alternative of surveying a smaller, presumably more densely populated, region
with a higher sensitivity would have a low return and would be impractical at a
transit instrument. (abridged)Comment: accepted for publication in Astronomy & Astrophysic
Impact of Point Spread Function Higher Moments Error on Weak Gravitational Lensing II: A Comprehensive Study
Weak gravitational lensing, or weak lensing, is one of the most powerful
probes for dark matter and dark energy science, although it faces increasing
challenges in controlling systematic uncertainties as \edit{the statistical
errors become smaller}. The Point Spread Function (PSF) needs to be precisely
modeled to avoid systematic error on the weak lensing measurements. The weak
lensing biases induced by errors in the PSF model second moments, i.e., its
size and shape, are well-studied. However, Zhang et al. (2021) showed that
errors in the higher moments of the PSF may also be a significant source of
systematics for upcoming weak lensing surveys. Therefore, the goal of this work
is to comprehensively investigate the modeling quality of PSF moments from the
to order, and estimate their impact on
cosmological parameter inference. We propagate the \textsc{PSFEx} higher
moments modeling error in the HSC survey dataset to the weak lensing
\edit{shear-shear correlation functions} and their cosmological analyses. We
find that the overall multiplicative shear bias associated with errors in PSF
higher moments can cause a shift on the cosmological
parameters for LSST Y10. PSF higher moment errors also cause additive biases in
the weak lensing shear, which, if not accounted for in the cosmological
parameter analysis, can induce cosmological parameter biases comparable to
their uncertainties for LSST Y10. We compare the \textsc{PSFEx} model
with PSF in Full FOV (\textsc{Piff}), and find similar performance in modeling
the PSF higher moments. We conclude that PSF higher moment errors of the future
PSF models should be reduced from those in current methods to avoid a need to
explicitly model these effects in the weak lensing analysis.Comment: 24 pages, 17 figures, 3 tables; Submitted to MNRAS; Comments welcome
Monophyly and phylogenetic origin of the gall crab family Cryptochiridae (Decapoda : Brachyura)
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