Abstract
We have matched the ultraviolet (UV) sources in
GUVcat
_AIS with optical databases that have similar depth and wide sky coverage.
GUVcat
_AIS has Galaxy Evolution Explorer (GALEX) far-UV ...(FUV,
λ
eff
∼ 1528 Å) and near-UV (NUV,
λ
eff
∼ 2310 Å) photometry of ≈83 million sources, covering 24,788 square degrees of the sky, with a typical depth of FUV = 19.9 and NUV = 20.8 AB mag. Matches with Gaia and the Sloan Digital Sky Survey (SDSS) databases are presented here. Gaia data release 2 (DR2), covering the entire
GUVcat
footprint, detected about one-third of the
GUVcat
_AIS sources. We found 31,925,294 Gaia DR2 counterparts to 30,024,791
GUVcat
_AIS unique sources, with photometry in the Gaia
G
band and often also in Gaia BP and RP bands; 26,275,572 matches have a parallax measurement, 21,084,628, 18,588,140, and 16,357,505 have a parallax error less than 50%, 30%, and 20%, respectively. The match with SDSS data release 14 (DR14) yields 23,310,532 counterparts to 22,207,563 unique
GUVcat
_AIS sources, 10,167,460 of which are pointlike, over a total overlap area of ≈11,100 square degrees (Bianchi et al. 2019). SDSS adds five optical magnitudes to the UV photometry :
u
,
g
,
r
,
i
,
z
, and optical spectra of 860,224 matched sources. We used a match radius of 3″, consistent with previous works, although the positions agree to ≲15 for the majority of (pointlike) matched sources, in order to identify possible multiple matches whose UV flux could be unresolved in GALEX imaging. The catalogs can be trimmed to a tighter match radius using the provided separation. The multiband photometry is used to identify classes of astrophysical objects that are prominent in UV, to characterize the content of the
GUVmatch
catalogs, where stars in different evolutionary stages, quasi-stellar objects, and galaxies can be separated.
We report on intriguing photometric properties of Galactic stars observed in the Galaxy Evolution Explorer (GALEX) satellite's far-UV (FUV) and near-UV (NUV) bandpasses, as well as from the ...ground-based Sloan Digital Sky Survey (SDSS) and the Kepler Input Catalog. Investigating this tendency further, we found in two samples of mid-F through K type stars that 17%-22% of them exhibit FUV excesses relative to their NUV fluxes and spectral types. A correction for FUV incompleteness of the FUV magnitude-limited star sample brings this ratio to 14%-18%. Nearly the same fractions are also discovered among members of the Kepler Eclipsing Binary Catalog and in the published list of Kepler Objects of Interest. We find that the subpopulation composing this island is mainly horizontal branch stars. This subpopulation appears "red" in the UV only because the stars' colors are not pulled to the blue by the inclusion of UVe stars.
We present a new, expanded and improved catalog of Ultraviolet (UV) sources from the GALEX All-Sky Imaging survey: GUVcat_AIS (Bianchi et al. in Astrophys. J. Suppl. Ser. 230:24,
2017
). The catalog ...includes 83 million unique sources (duplicate measurements and rim artifacts are removed) measured in far-UV and near-UV. With respect to previous versions (Bianchi et al. in Mon. Not. R. Astron. Soc. 411:2770
2011a
, Adv. Space Res. 53:900–991,
2014
), GUVcat_AIS covers a slightly larger area, 24,790 square degrees, and includes critical corrections and improvements, as well as new tags, in particular to identify sources in the footprint of extended objects, where pipeline source detection may fail and custom-photometry may be necessary. The UV unique-source catalog facilitates studies of density of sources, and matching of the UV samples with databases at other wavelengths.
We also present first results from two ongoing projects, addressing respectively UV variability searches on time scales from seconds to years by mining the GALEX photon archive, and the construction of a database of ∼120,000 GALEX UV spectra (range ∼1300–3000 Å), including quality and calibration assessment and classification of the grism, hence serendipitous, spectral sources.
We have matched the ultraviolet (UV) sources in GUVcat_AIS (Bianchi et al.2017) with optical databases having similar depth and wide sky coverage. GUVcat_AIS has GALEX far-UV (FUV, lambda-eff ...~1528\AA ) and near-UV (NUV, lambda-eff ~2310\AA) photometry of approx 83~million sources, covering 24,788 square degrees of the sky, with typical depth of FUV=19.9, NUV=20.8~ABmag. Matches with Gaia and SDSS databases are presented here. Gaia data release 2 (DR2), covering the entire GUVcat footprint (Bianchi et al. 2019), detected about one third of the \(GUVcat\_AIS\) sources. We found 31,925,294 Gaia~DR2 counterparts to 30,024,791 GUVcat_AIS unique sources, with photometry in \(Gaia\)~\(G\) band, and often also in \(Gaia\)~\(BP\) and \(RP\) bands; 26,275,572 matches have a parallax measurement, 21,084,628/18,588,140/16,357,505 with parallax error less than 50%/30%/20%. The match with SDSS data release 14 (DR14) yields 23,310,532 counterparts to 22,207,563 unique GUVcat_AIS sources, 10,167,460 of which are point-like, over a total overlap area of \(\approx\)11,100~square~degrees (Bianchi et al. 2019)}. SDSS adds to the UV photometry five optical magnitudes: \(u,g,r,i,z\), and optical spectra of 860,224 matched sources. We used a match radius of 3arcsec, consistent with previous works (e.g., Bianchi et al. 2011a), although the positions agree to \(\lesssim\)1.5arcsec for the majority of point-like matched-sources, in order to identify possible multiple matches whose UV flux could be unresolved in GALEX imaging. The catalogs can be trimmed to a tighter match radius using the provided separation. The multi-band photometry is used to identify classes of astrophysical objects that are prominent in UV, to characterise the content of the \(GUVmatch\) catalogs, where stars in different evolutionary stages, QSOs, and galaxies can be separated.
The Galaxy Evolution Explorer (GALEX) imaged the sky in two Ultraviolet (UV) bands, far-UV (FUV) and near-UV (NUV), delivering the first comprehensive sky surveys at these wavelengths. The GALEX ...database contains FUV and NUV images, 500~million source measurements and over 100,000 low-resolution UV spectra. ... We present science-enhanced, clean catalogs of GALEX UV sources, with useful tags to facilitate scientific investigations. The catalogs are an improved and expanded version of our previous catalogs of UV sources (Bianchi et al. 2011, 2014: BCScat). With respect to BCScat, we have patched 640 fields for which the pipeline had improperly coadded non-overlapping observations, we provide a version with a larger sky coverage (about 10percent) .... We added new tags to facilitate selection and cleaning of statistical samples...: we flag sources within the footprint of extended objects (nearby galaxies, stellar clusters) so that these regions can be excluded for estimating source density. As in our previous catalogs, in GUVcat duplicate measurements of the same source are removed.... Such unique-source catalog is needed to study density and distributions of sources, and to match UV sources with catalogs at other wavelengths. The catalog includes all observations from the All-Sky Imaging Survey (AIS), the survey with the largest area coverage, with both FUV and NUV detectors exposed: over 28,700 fields, made up of a total of 57,000 observations ("visits"). The total area covered, when overlaps are removed and gaps accounted for, is 24,790 (GUVcat_AIS_fov055) and 22,125 (GUVcat_AIS_fov050) square degrees. The total number of unique AIS sources (eliminating duplicate measurements) is 82,992,086 (GUVcat_AIS_fov055) and 69,772,677 (GUVcat_AIS_fov050). The typical depth of the GUVcat_AIS catalog is FUV=19.9, NUV=20.8ABmag.
We report on intriguing photometric properties of Galactic stars observed in the GALEX satellite's far-UV and near-UV bandbasses as well as from the SDSS survey and the Kepler Input Catalog. First, ...the FUV-NUV color distribution of stars in the Kepler field consists of 2 distinct peaks. Second, curiously, for stars with spectral types G or later the mean FUV-NUV color becomes much bluer, contrary to expectation. we have found in two samples of mid-F through K type stars that ~14-18% of them exhibit FUV-excesses relative to their NUV fluxes and spectral types. Nearly the same fractions are also discovered among members of the Kepler Eclipsing Binary Catalog and in the published list of Kepler Objects of Interest. These UV-excess ("UVe") colors are confirmed by the UV continuum slopes in GALEX spectra. The SDSS spectra of some UVe stars exhibit metallic line weakening especially in the blue. This suggests an enhanced contribution of UV flux relative to photospheric flux of a solar-type single star. We consider the possibility that the UV excesses originate from various types of hot stars, including binaries, and strong chromosphere stars that. Our model atmosphere-derived simulations of colors for binaries with main sequence pairs with a hot secondary demonstrate that the color loci conflict with the observed sequence. We are left with the active chromospheres explanation, whether in active binaries or young stars, as a still tentative explanation for the UVe stars. We also address the presence of an island of "UV red" stars in the NUV-g, g-i color diagram. The subpopulation comprising this island are mainly horizontal branch stars. These objects do not exhibit UV excesses and therefore have UV colors typical for their spectral types. This subpopulation appears "red" in the UV because their colors are not pulled to the blue by the UVe stars.
We investigated whether adding anthropometric measures to HbA1c would have stronger discriminative ability over HbA1c alone in detecting dysglycemia (diabetes and prediabetes) among Asian women ...trying to conceive. Among 971 Singaporean women, multiple regression models and area under receiver-operating characteristic (AUROC) curves were used to analyze associations of anthropometric (weight, height, waist/hip circumferences, 4-site skinfold thicknesses) and HbA1c z-scores with dysglycemia (fasting glucose ≥6.1 mmol/L with 2-hour glucose ≥7.8 mmol/l). The prevalence of dysglycemia was 10.9%. After adjusting for sociodemographic/medical history, BMI (Odds Ratio OR = 1.62 95%CI 1.32-1.99), waist-to-height ratio (OR = 1.74 1.39-2.17) and total skinfolds (OR = 2.02 1.60-2.55) showed the strongest associations with dysglycemia but none outperformed HbA1c (OR = 4.09 2.81-5.94). After adjustment for history, adding BMI, waist-to-height ratio and total skinfolds (anthropometry trio) as continuous variables to HbA1c (AUROC = 0.80 95%CI 0.75-0.85) performed similarly to HbA1c alone (AUROC = 0.79 0.74-0.84). However, using clinically-defined thresholds without considering history, as in common clinical practice, BMI ≥ 23 kg/m
+ HbA1c ≥ 5.7% (AUROC = 0.70 0.64-0.75) and anthropometry trio + HbA1c ≥ 5.7% (AUROC = 0.71 0.65-0.76) both outperformed HbA1c ≥ 5.7% alone (AUROC = 0.61 0.57-0.65). In a two-stage strategy, incorporating BMI ≥ 23 kg/m
alongside HbA1c ≥ 5.7% into first-stage screening to identify high risk women for subsequent oral glucose tolerance testing improves dysglycemia detection in Asian women preconception.
Integrated 24-Hour Movement Guidelines provide specific recommendations on screen viewing (SV), moderate-to-vigorous physical activity (MVPA) and sleep to improve health of children and youth. ...However, few studies have examined whether these guidelines are met in young children, particularly in Asia. We evaluated adherence to integrated and individual guidelines and its predictors in 5.5-year-old Singaporean children.
Growing Up in Singapore towards Healthy Outcomes (GUSTO) is a mother-offspring birth cohort study. At age 5.5 years, child SV was reported by parents. Movement behaviours (MBs) were measured continuously using wrist-worn accelerometers over 7 consecutive days and nights. For accelerometer data including ≥3 days with ≥16 h/day we estimated mean (±SD) daily MVPA, SV and nighttime sleep duration across the week. Adherence to integrated (Canadian/Australian) guidelines was defined as meeting all individual guidelines: ≥60 min of MVPA/day, ≤2 h of screen time/day, and 9-11 h of sleep/night. Socio-demographic and maternal predictors collected at pregnancy enrolment and at 26-28 weeks' gestation were examined by multivariable logistic regression.
Of 864 children followed up age 5.5 years, 547 (63.3%) had both valid ActiGraph and questionnaire data (51.7% boys and 58.3% Chinese ethnicity). Children averaged 101.9 (± 88.7) min/day SV, 67.3 (± 23.7) min/day MVPA and 480.6 (± 57.2) min/night sleep. Few children met integrated guidelines. Specifically, the proportions of children who met none, SV, MVPA, sleep and integrated guidelines were 11.2, 70.2, 59.6, 13.7 and 5.5%, respectively. Multivariable analysis showed that maternal activity and television (TV) viewing were associated with meeting integrated guidelines (insufficiently vs. highly active (OR 95% CI): 0.11 0.01, 0.95; 2-3 vs. ≥ 3 h TV: 3.52 1.02, 12.22). Examining higher adherence to individual guidelines, Chinese ethnicity, younger maternal age and lower maternal TV and sleep time were associated with greater SV; male sex, Malay ethnicity, higher birth order and higher maternal activity level were associated with greater MVPA; and older maternal age was associated with adherence to sleep guideline.
Beyond individual behaviours, consideration of the full spectrum of MBs may be important to improve children's health. However, few Singaporean children adhere to integrated 24-h movement guidelines. Maternal behaviours as early as during pregnancy could be important targets for future interventions aiming to promote these MBs in children.
Time spent in movement behaviours, including physical activity (PA), sedentary behaviour (SB) and sleep, across the 24-h day may have distinct health consequences. We aimed to describe 24-h movement ...behaviour (24 h-MB) profiles in children and how profile membership changed from age 5.5 to 8 years.
Children in the Growing Up in Singapore Towards healthy Outcomes (GUSTO) cohort were asked to wear an accelerometer (ActiGraph-GT3X+) on their wrist for seven consecutive days at ages 5.5 and 8 years to measure 24 h-MB patterns. Time spent in night sleep, inactivity (proxy for SB), light PA, moderate PA (MPA), and vigorous PA (VPA) per day were calculated using the R-package GGIR 2.0. Using latent profile analyses (n = 442) we identified 24 h-MB profiles, which were given animal names to convey key characteristics. Latent transition analyses were used to describe the profile membership transition from ages 5.5 to 8 years. Associations with sex and ethnicity were examined.
We identified four profiles, "Rabbits" (very high-MPA/VPA, low-inactivity and average-night-sleep), "Chimpanzees" (high-MPA, low-inactivity and average-night-sleep), "Pandas" (low-PA, high-inactivity and high-night-sleep) and "Owls" (low-PA, high-inactivity and low-night-sleep), among children at both time points. At ages 5.5 and 8 years, the majority of children were classified into profiles of "Chimpanzees" (51 and 39%, respectively) and "Pandas" (24 and 37%). Half of the sample (49%), particularly "Rabbits", remained in the same profile at ages 5.5 and 8 years: among children who changed profile the predominant transitions occurred from "Chimpanzees" (27%) and "Owls" (56%) profiles to "Pandas". Sex, but not ethnicity, was associated with profile membership: compared to girls, boys were more likely to be in the "Rabbits" profile (adjusted OR 95% CI: 3.6 1.4, 9.7 and 4.5 1.8, 10.9 at ages 5.5 and 8 years, respectively) and less likely to be in the "Pandas" profile (0.5 0.3, 0.9 and 0.4 0.2, 0.6) at both ages.
With increasing age about half the children stayed in the same of four 24 h-MB profiles, while the predominant transition for the remaining children was towards lower PA, higher inactivity and longer sleep duration. These findings can aid development and implementation of public health strategies to promote better health.
This study was registered on 4th August 2010 and is available online at ClinicalTrials.gov: NCT01174875 .
Parental practices and neighbourhood environmental factors may influence children's movement behaviours. We aimed to investigate the cross-sectional and prospective associations of parental practices ...and neighbourhood environmental factors with accelerometer-measured 24-hour movement behaviours (24 h-MBs) among school-aged children in Singapore.
The Growing Up in Singapore Towards healthy Outcomes (GUSTO) study collected information on dimensions of parental practices and neighbourhood environment at age 5.5 years. Confirmatory factor analyses were performed to generate latent variables and used to compute overall parental practices involvement in PA + support for PA + control of screen viewing context and environmental scores facilities for active play + active mobility facilitators + barriers*-1. Children wore an accelerometer on their non-dominant wrist for seven consecutive days at ages 5.5 and 8 years. The R-package GGIR 2.6 was used to derive moderate-to-vigorous-intensity physical activity (MVPA), light-intensity physical activity (LPA), inactivity, and total-sleep (napping+night sleep) minutes per day. Associations were determined using compositional data analysis with multivariate linear regression models, taking into account potential confounders.
Among 425 children (48% girls, 59% Chinese), higher parental involvement in PA, parental support for PA and overall parental practices were associated with 24 h-MBs at ages 5.5 and 8 years, specifically with greater time spent in MVPA and less time being inactive relative to the remaining movement behaviours. The corresponding mean changes in the overall 24 h-MB for increasing parental practices from lowest to highest scores (- 2 to + 2 z-scores) indicated potential increases of up to 15-minutes in MVPA, 20-minutes in LPA, 5-minutes in sleep duration, and a reduction of 40-minutes in inactivity at age 5.5 years. At age 8 years, this could translate to approximately 15-minutes more of MVPA, 20-minutes more of LPA, a 20-minute reduction in sleep duration, and a 20-minute reduction in inactivity. Parental control of screen viewing contexts and neighbourhood environmental factors were not associated with 24 h-MBs.
Parental practices but not environmental factors were associated with higher MVPA and lower inactivity among Singaporean children, even at a later age. Further research may provide insights that support development of targeted public health strategies to promote healthier movement behaviours among children.
This study was registered on 4th August 2010 and is available online at ClinicalTrials.gov: NCT01174875.
PDF
