Abstract
The Vera Rubin Observatory Legacy Survey of Space and Time (LSST) is expected to process ∼10
6
transient detections per night. For precision measurements of cosmological parameters and ...rates, it is critical to understand the detection efficiency, magnitude limits, artifact contamination levels, and biases in the selection and photometry. Here we rigorously test the LSST Difference Image Analysis (DIA) pipeline using simulated images from the Rubin Observatory LSST Dark Energy Science Collaboration Data Challenge (DC2) simulation for the Wide-Fast-Deep survey area. DC2 is the first large-scale (300 deg
2
) image simulation of a transient survey that includes realistic cadence, variable observing conditions, and CCD image artifacts. We analyze ∼15 deg
2
of DC2 over a 5 yr time span in which artificial point sources from Type Ia supernova (SNIa) light curves have been overlaid onto the images. The magnitude limits per filter are
u
= 23.66 mag,
g
= 24.69 mag,
r
= 24.06 mag,
i
= 23.45 mag,
z
= 22.54 mag, and
y
= 21.62 mag. The artifact contamination levels are ∼90% of all detections, corresponding to ∼1000 artifacts deg
–2
in
g
band, and falling to 300 deg
–2
in
y
band. The photometry has biases <1% for magnitudes 19.5 <
m
< 23. Our DIA performance on simulated images is similar to that of the Dark Energy Survey difference-imaging pipeline on real images. We also characterize DC2 image properties to produce catalog-level simulations needed for distance bias corrections. We find good agreement between DC2 data and simulations for distributions of signal-to-noise ratio, redshift, and fitted light-curve properties. Applying a realistic SNIa cosmology analysis for redshifts
z
< 1, we recover the input cosmology parameters to within statistical uncertainties.
ABSTRACT
We present and validate 20 deg2 of overlapping synthetic imaging surveys representing the full depth of the Nancy Grace Roman Space Telescope High-Latitude Imaging Survey (HLIS) and 5 yr of ...observations of the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). The two synthetic surveys are summarized, with reference to the existing 300 deg2 of LSST simulated imaging produced as part of Dark Energy Science Collaboration (DESC) Data Challenge 2 (DC2). Both synthetic surveys observe the same simulated DESC DC2 universe. For the synthetic Roman survey, we simulate for the first time fully chromatic images along with the detailed physics of the Sensor Chip Assemblies derived from lab measurements using the flight detectors. The simulated imaging and resulting pixel-level measurements of photometric properties of objects span a wavelength range of ∼0.3–2.0 μm. We also describe updates to the Roman simulation pipeline, changes in how astrophysical objects are simulated relative to the original DC2 simulations, and the resulting simulated Roman data products. We use these simulations to explore the relative fraction of unrecognized blends in LSST images, finding that 20–30 per cent of objects identified in LSST images with i-band magnitudes brighter than 25 can be identified as multiple objects in Roman images. These simulations provide a unique testing ground for the development and validation of joint pixel-level analysis techniques of ground- and space-based imaging data sets in the second half of the 2020s – in particular the case of joint Roman–LSST analyses.
Despite the tremendous advances in laser cooling of neutral atoms and positive ions, no negatively charged ion has been directly laser cooled. The negative ion of lanthanum, La(-), has been proposed ...as the best candidate for laser cooling of any atomic anion and , Phys. Rev. A 81, 032503 (2010). Tunable infrared laser photodetachment spectroscopy is used to measure the bound-state structure of La(-), revealing a spectrum of unprecedented richness with multiple bound-bound electric dipole transitions. The potential laser-cooling transition ((3)F(2)(e)→(3)D(1)(o)) is identified and its excitation energy is measured. The results confirm that La^{-} is a very promising negative ion for laser-cooling applications.
The authors conducted a systematic review of published data on the association between diabetes mellitus and fracture. The authors searched MEDLINE through June 2006 and examined the reference lists ...of pertinent articles (limited to studies in humans). Summary relative risks and 95% confidence intervals were calculated with a random-effects model. The 16 eligible studies (two case-control studies and 14 cohort studies) included 836,941 participants and 139,531 incident cases of fracture. Type 2 diabetes was associated with an increased risk of hip fracture in both men (summary relative risk (RR) = 2.8, 95% confidence interval (CI): 1.2, 6.6) and women (summary RR = 2.1, 95% CI: 1.6, 2.7). Results were consistent between studies of men and women and between studies conducted in the United States and Europe. The association between type of diabetes and hip fracture incidence was stronger for type 1 diabetes (summary RR = 6.3, 95% CI: 2.6, 15.1) than for type 2 diabetes (summary RR = 1.7, 95% CI: 1.3, 2.2). Type 2 diabetes was weakly associated with fractures at other sites, and most effect estimates were not statistically significant. These findings strongly support an association between both type 1 and type 2 diabetes and increased risk of hip fracture in men and women.
Summary Current intake recommendations of 200 to 600 IU vitamin D per day may be insufficient for important disease outcomes reduced by vitamin D. Introduction This study assessed the benefit of ...higher-dose and higher achieved 25-hydroxyvitamin D levels 25(OH)D versus any associated risk. Methods and results Based on double-blind randomized control trials (RCTs), eight for falls (n = 2426) and 12 for non-vertebral fractures (n = 42,279), there was a significant dose-response relationship between higher-dose and higher achieved 25(OH)D and greater fall and fracture prevention. Optimal benefits were observed at the highest dose tested to date for 700 to 1000 IU vitamin D per day or mean 25(OH)D between 75 and 110 nmol/l (30-44 ng/ml). Prospective cohort data on cardiovascular health and colorectal cancer prevention suggested increased benefits with the highest categories of 25(OH)D evaluated (median between 75 and 110 nmol/l). In 25 RCTs, mean serum calcium levels were not related to oral vitamin D up to 100,000 IU per day or achieved 25(OH)D up to 643 nmol/l. Mean levels of 75 to 110 nmol/l were reached in most RCTs with 1,800 to 4,000 IU vitamin D per day without risk. Conclusion Our analysis suggests that mean serum 25(OH)D levels of about 75 to 110 nmol/l provide optimal benefits for all investigated endpoints without increasing health risks. These levels can be best obtained with oral doses in the range of 1,800 to 4,000 IU vitamin D per day; further work is needed, including subject and environment factors, to better define the doses that will achieve optimal blood levels in the large majority of the population.
For a fixed amount of time engaged in physical activity, activity choice may affect body weight differently depending partly on other activities’ displacement. Typical models used to evaluate effects ...of physical activity on body weight do not directly address these substitutions. An isotemporal substitution paradigm was developed as a new analytic model to study the time-substitution effects of one activity for another. In 1991–1997, the authors longitudinally examined the associations of discretionary physical activities, with varying activity displacements, with 6-year weight loss maintenance among 4,558 healthy, premenopausal US women who had previously lost >5% of their weight. Results of isotemporal substitution models indicated widely heterogeneous relations with each physical activity type (P < 0.001) depending on the displaced activities. Notably, whereas 30 minutes/day of brisk walking substituted for 30 minutes/day of jogging/running was associated with weight increase (1.57 kg, 95% confidence interval: 0.33, 2.82), brisk walking was associated with lower weight when substituted for slow walking (−1.14 kg, 95% confidence interval: −1.75, −0.53) and with even lower weight when substituted for TV watching. Similar heterogeneous relations with weight change were found for each activity type (TV watching, slow walking, brisk walking, jogging/running) when displaced by other activities across these various models. The isotemporal substitution paradigm may offer new insights for future public health recommendations.
Abstract
The presence of fringing in astronomical Charge-Coupled Device (CCD) images will have an impact on photometric quality and measurements. Yet its impact on the Vera C. Rubin Observatory’s ...Legacy Survey of Space and Time (LSST) has not been fully studied. We present a detailed study on fringing for CCDs already implemented on the Rubin Observatory LSST Camera’s focal plane. After making physical measurements and knowing the compositions, we developed a model for the e2v CCDs. We present a method to fit for the internal height variation of the epoxy layer within the sensors based on fringing measurements in a laboratory setting. This method is generic enough that it can be easily modified to work for other CCDs. Using the derived fringing model, we successfully reproduce comparable fringing amplitudes that match the observed levels in images taken by existing telescopes with different optical designs. This model is then used to forecast the expected level of fringing in a single LSST
y
-band sky background exposure with Rubin telescope optics in the presence of a realistic time-varying sky spectrum. The predicted fringing amplitude in LSST images ranges from 0.04% to 0.2% depending on the location of a CCD on the focal plane. We find that the predicted variation in surface brightness caused by fringing in LSST
y
-band sky background images is about 0.6
μ
Jy
arcsec
−
2
, which is 40 times larger than the current measurement error. We conclude that it is necessary to include fringing correction in the Rubin’s LSST image processing pipeline.
Similarities between Alzheimer disease (AD) and Parkinson disease (PD) suggest a possible role for apolipoprotein E (APOE) in PD. Most previous studies seeking to establish such a link used ...case-control datasets and results have been inconsistent.
To investigate APOE's role in PD using family-based association analyses.
APOE functional polymorphisms were genotyped for 658 PD affected families, including 282 multiplex and 376 singleton families. The pedigree disequilibrium test (PDT) and the genotype-PDT were used to test the risk effect of APOE. The Monks-Kaplan test was used to evaluate the effect of APOE on age at onset of PD.
APOE was significantly associated with risk of developing PD. Stratified analysis revealed that APOE was most strongly associated with families with a positive PD family history (global p = 0.003). Like AD, the APOE-4 allele increases disease risk while the APOE-3 allele decreases risk. We detected a positive association of APOE-3 (p = 0.019) and a negative association of APOE-4 (p = 0.015) with age at onset in PD.
The APOE-4 allele increases risk and decreases age at onset of PD, an association that may not be dependent upon cognitive impairment.
We characterize the dust in NGC 628 and NGC 6946, two nearby spiral galaxies in the KINGFISH sample. With data from 3.6 mu m to 500 mu m, dust models are strongly constrained. Using the Draine & Li ...dust model (amorphous silicate and carbonaceous grains), for each pixel in each galaxy we estimate (1) dust mass surface density, (2) dust mass fraction contributed by polycyclic aromatic hydrocarbons, (3) distribution of starlight intensities heating the dust, (4) total infrared (IR) luminosity emitted by the dust, and (5) IR luminosity originating in regions with high starlight intensity. We obtain maps for the dust properties, which trace the spiral structure of the galaxies. The dust models successfully reproduce the observed global and resolved spectral energy distributions (SEDs). The overall dust/H mass ratio is estimated to be 0.0082 + or - 0.0017 for NGC 628, and 0.0063 + or - 0.0009 for NGC 6946, consistent with what is expected for galaxies of near-solar metallicity. Our derived dust masses are larger (by up to a factor of three) than estimates based on single-temperature modified blackbody fits. We show that the SED fits are significantly improved if the starlight intensity distribution includes a (single intensity) "delta function" component. We find no evidence for significant masses of cold dust (T <, ~ 12 K). Discrepancies between PACS and MIPS photometry in both low and high surface brightness areas result in large uncertainties when the modeling is done at PACS resolutions, in which case SPIRE, MIPS70, and MIPS160 data cannot be used. We recommend against attempting to model dust at the angular resolution of PACS.
Archaeological evidence suggests that dogs were introduced to the islands of Oceania via Island Southeast Asia around 3,300 years ago, and reached the eastern islands of Polynesia by the fourteenth ...century AD. This dispersal is intimately tied to human expansion, but the involvement of dogs in Pacific migrations is not well understood. Our analyses of seven new complete ancient mitogenomes and five partial mtDNA sequences from archaeological dog specimens from Mainland and Island Southeast Asia and the Pacific suggests at least three dog dispersal events into the region, in addition to the introduction of dingoes to Australia. We see an early introduction of dogs to Island Southeast Asia, which does not appear to extend into the islands of Oceania. A shared haplogroup identified between Iron Age Taiwanese dogs, terminal-Lapita and post-Lapita dogs suggests that at least one dog lineage was introduced to Near Oceania by or as the result of interactions with Austronesian language speakers associated with the Lapita Cultural Complex. We did not find any evidence that these dogs were successfully transported beyond New Guinea. Finally, we identify a widespread dog clade found across the Pacific, including the islands of Polynesia, which likely suggests a post-Lapita dog introduction from southern Island Southeast Asia.
PDF
