| 1. |
- Bellenguez, Celine, et al.
(författare)
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Genome-wide association study identifies a variant in HDAC9 associated with large vessel ischemic stroke
- 2012
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 44:3, s. 141-328
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Tidskriftsartikel (refereegranskat)abstract
- Genetic factors have been implicated in stroke risk, but few replicated associations have been reported. We conducted a genome-wide association study (GWAS) for ischemic stroke and its subtypes in 3,548 affected individuals and 5,972 controls, all of European ancestry. Replication of potential signals was performed in 5,859 affected individuals and 6,281 controls. We replicated previous associations for cardioembolic stroke near PITX2 and ZFHX3 and for large vessel stroke at a 9p21 locus. We identified a new association for large vessel stroke within HDAC9 (encoding histone deacetylase 9) on chromosome 7p21.1 (including further replication in an additional 735 affected individuals and 28,583 controls) (rs11984041; combined P = 1.87 x 10(-11); odds ratio (OR) = 1.42, 95% confidence interval (CI) = 1.28-1.57). All four loci exhibited evidence for heterogeneity of effect across the stroke subtypes, with some and possibly all affecting risk for only one subtype. This suggests distinct genetic architectures for different stroke subtypes.
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| 2. |
- Jencson, Jacob E., et al.
(författare)
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Discovery of an Intermediate-luminosity Red Transient in M51 and Its Likely Dust-obscured, Infrared-variable Progenitor
- 2019
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 880:2
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Tidskriftsartikel (refereegranskat)abstract
- We present the discovery of an optical transient (OT) in Messier. 51, designated M51 OT2019-1 (also ZTF 19aadyppr, AT 2019abn, ATLAS19bz1), by the Zwicky Transient Facility (ZTF). The OT rose over 15. days to an observed luminosity of M-r = -13 (nu L-nu = 9 x 10(6) L-circle dot), in the luminosity gap between novae and typical supernovae (SNe). Spectra during the outburst show a red continuum, Balmer emission with a velocity width of approximate to 400 km s(-1), Ca II and [Ca II] emission, and absorption features characteristic of an F-type supergiant. The spectra and multiband light curves are similar to the so-called SN impostors and intermediate-luminosity red transients (ILRTs). We directly identify the likely progenitor in archival Spitzer Space Telescope imaging with a 4.5 mu m luminosity of M-[4.5] approximate to -12.2 mag and a [3.6]-[4.5] color redder than 0.74 mag, similar to those of the prototype ILRTs SN 2008S and NGC 300 OT2008-1. Intensive monitoring of M51 with Spitzer further reveals evidence for variability of the progenitor candidate at [ 4.5] in the years before the OT. The progenitor is not detected in pre-outburst Hubble Space Telescope optical and near-IR images. The optical colors during outburst combined with spectroscopic temperature constraints imply a higher reddening of E(B - V) approximate to 0.7 mag and higher intrinsic luminosity of M-r approximate to -14.9 mag (nu L-nu = 5.3 x 10(7) L-circle dot) near peak than seen in previous ILRT candidates. Moreover, the extinction estimate is higher on the rise than on the plateau, suggestive of an extended phase of circumstellar dust destruction. These results, enabled by the early discovery of M51. OT2019-1 and extensive pre-outburst archival coverage, offer new clues about the debated origins of ILRTs and may challenge the hypothesis that they arise from the electron-capture induced collapse of extreme asymptotic giant branch stars.
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| 3. |
- Palmer, Nicholette D, et al.
(författare)
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A genome-wide association search for type 2 diabetes genes in African Americans.
- 2012
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Ingår i: PloS one. - San Francisco : Public Library of Science (PLoS). - 1932-6203. ; 7:1, s. e29202-
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Tidskriftsartikel (refereegranskat)abstract
- African Americans are disproportionately affected by type 2 diabetes (T2DM) yet few studies have examined T2DM using genome-wide association approaches in this ethnicity. The aim of this study was to identify genes associated with T2DM in the African American population. We performed a Genome Wide Association Study (GWAS) using the Affymetrix 6.0 array in 965 African-American cases with T2DM and end-stage renal disease (T2DM-ESRD) and 1029 population-based controls. The most significant SNPs (n = 550 independent loci) were genotyped in a replication cohort and 122 SNPs (n = 98 independent loci) were further tested through genotyping three additional validation cohorts followed by meta-analysis in all five cohorts totaling 3,132 cases and 3,317 controls. Twelve SNPs had evidence of association in the GWAS (P<0.0071), were directionally consistent in the Replication cohort and were associated with T2DM in subjects without nephropathy (P<0.05). Meta-analysis in all cases and controls revealed a single SNP reaching genome-wide significance (P<2.5×10(-8)). SNP rs7560163 (P = 7.0×10(-9), OR (95% CI) = 0.75 (0.67-0.84)) is located intergenically between RND3 and RBM43. Four additional loci (rs7542900, rs4659485, rs2722769 and rs7107217) were associated with T2DM (P<0.05) and reached more nominal levels of significance (P<2.5×10(-5)) in the overall analysis and may represent novel loci that contribute to T2DM. We have identified novel T2DM-susceptibility variants in the African-American population. Notably, T2DM risk was associated with the major allele and implies an interesting genetic architecture in this population. These results suggest that multiple loci underlie T2DM susceptibility in the African-American population and that these loci are distinct from those identified in other ethnic populations.
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| 4. |
- Biswas, Rahul, et al.
(författare)
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Two c's in a pod : cosmology-independent measurement of the Type Ia supernova colour-luminosity relation with a sibling pair
- 2022
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 509:4, s. 5340-5356
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Tidskriftsartikel (refereegranskat)abstract
- Using Zwicky Transient Facility (ZTF) observations, we identify a pair of ‘sibling’ Type Ia supernovae (SNe Ia), i.e. hosted by the same galaxy at z = 0.0541. They exploded within 200 d from each other at a separation of 0.6arcsec0.6arcsec corresponding to a projected distance of only 0.6 kpc. Performing SALT2 light-curve fits to the gri ZTF photometry, we show that for these equally distant ‘standardizable candles’, there is a difference of 2 mag in their rest-frame B-band peaks, and the fainter supernova (SN) has a significantly red SALT2 colour c = 0.57 ± 0.04, while the stretch values x1 of the two SNe are similar, suggesting that the fainter SN is attenuated by dust in the interstellar medium of the host galaxy. We use these measurements to infer the SALT2 colour standardization parameter, β = 3.5 ± 0.3, independent of the underlying cosmology and Malmquist bias. Assuming the colour excess is entirely due to dust, the result differs by 2σ from the average Milky Way total-to-selective extinction ratio, but is in good agreement with the colour–brightness corrections empirically derived from the most recent SN Ia Hubble–Lemaitre diagram fits. Thus we suggest that SN ‘siblings’, which will increasingly be discovered in the coming years, can be used to probe the validity of the colour and light-curve shape corrections using in SN Ia cosmology while avoiding important systematic effects in their inference from global multiparameter fits to inhomogeneous data sets, and also help constrain the role of interstellar dust in SN Ia cosmology.
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| 5. |
- Cheng, Yu-Ching, et al.
(författare)
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Genome-Wide Association Analysis of Young-Onset Stroke Identifies a Locus on Chromosome 10q25 Near HABP2.
- 2016
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Ingår i: Stroke; a journal of cerebral circulation. - 1524-4628. ; 47:2, s. 307-16
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Tidskriftsartikel (refereegranskat)abstract
- Although a genetic contribution to ischemic stroke is well recognized, only a handful of stroke loci have been identified by large-scale genetic association studies to date. Hypothesizing that genetic effects might be stronger for early- versus late-onset stroke, we conducted a 2-stage meta-analysis of genome-wide association studies, focusing on stroke cases with an age of onset <60 years.
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| 6. |
- Cole, John W, et al.
(författare)
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Genetics of the thrombomodulin-endothelial cell protein C receptor system and the risk of early-onset ischemic stroke.
- 2018
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 13:11
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Tidskriftsartikel (refereegranskat)abstract
- Polymorphisms in coagulation genes have been associated with early-onset ischemic stroke. Here we pursue an a priori hypothesis that genetic variation in the endothelial-based receptors of the thrombomodulin-protein C system (THBD and PROCR) may similarly be associated with early-onset ischemic stroke. We explored this hypothesis utilizing a multi-stage design of discovery and replication.Discovery was performed in the Genetics-of-Early-Onset Stroke (GEOS) Study, a biracial population-based case-control study of ischemic stroke among men and women aged 15-49 including 829 cases of first ischemic stroke (42.2% African-American) and 850 age-comparable stroke-free controls (38.1% African-American). Twenty-four single-nucleotide-polymorphisms (SNPs) in THBD and 22 SNPs in PROCR were evaluated. Following LD pruning (r2≥0.8), we advanced uncorrelated SNPs forward for association analyses. Associated SNPs were evaluated for replication in an early-onset ischemic stroke population (onset-age<60 years) consisting of 3676 cases and 21118 non-stroke controls from 6 case-control studies. Lastly, we determined if the replicated SNPs also associated with older-onset ischemic stroke in the METASTROKE data-base.Among GEOS Caucasians, PROCR rs9574, which was in strong LD with 8 other SNPs, and one additional independent SNP rs2069951, were significantly associated with ischemic stroke (rs9574, OR = 1.33, p = 0.003; rs2069951, OR = 1.80, p = 0.006) using an additive-model adjusting for age, gender and population-structure. Adjusting for risk factors did not change the associations; however, associations were strengthened among those without risk factors. PROCR rs9574 also associated with early-onset ischemic stroke in the replication sample (OR = 1.08, p = 0.015), but not older-onset stroke. There were no PROCR associations in African-Americans, nor were there any THBD associations in either ethnicity.PROCR polymorphisms are associated with early-onset ischemic stroke in Caucasians.
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| 7. |
- De, Kishalay, et al.
(författare)
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The Zwicky Transient Facility Census of the Local Universe. I. Systematic Search for Calcium-rich Gap Transients Reveals Three Related Spectroscopic Subclasses
- 2020
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 905:1
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Tidskriftsartikel (refereegranskat)abstract
- Using the Zwicky Transient Facility alert stream, we are conducting a large spectroscopic campaign to construct a complete, volume-limited sample of transients brighter than 20 mag, and coincident within 100 '' of galaxies in the Census of the Local Universe catalog. We describe the experiment design and spectroscopic completeness from the first 16 months of operations, which have classified 754 supernovae. We present results from a systematic search for calcium-rich gap transients in the sample of 22 low-luminosity (peak absolute magnitude M > -17), hydrogen-poor events found in the experiment. We report the detection of eight new events, and constrain their volumetric rate to greater than or similar to 15% +/- 5% of the SN Ia rate. Combining this sample with 10 previously known events, we find a likely continuum of spectroscopic properties ranging from events with SN Ia-like features (Ca-Ia objects) to those with SN Ib/c-like features (Ca-Ib/c objects) at peak light. Within the Ca-Ib/c events, we find two populations distinguished by their red (g - r approximate to 1.5 mag) or green (g - r approximate to 0.5 mag) colors at the r-band peak, wherein redder events show strong line blanketing features and slower light curves (similar to Ca-Ia objects), weaker He lines, and lower [Ca II]/[O I] in the nebular phase. We find that all together the spectroscopic continuum, volumetric rates, and striking old environments are consistent with the explosive burning of He shells on low-mass white dwarfs. We suggest that Ca-Ia and red Ca-Ib/c objects arise from the double detonation of He shells, while green Ca-Ib/c objects are consistent with low-efficiency burning scenarios like detonations in low-density shells or deflagrations.
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| 8. |
- Kasliwal, Mansi M., et al.
(författare)
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Kilonova Luminosity Function Constraints Based on Zwicky Transient Facility Searches for 13 Neutron Star Merger Triggers during O3
- 2020
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 905:2
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Tidskriftsartikel (refereegranskat)abstract
- We present a systematic search for optical counterparts to 13 gravitational wave (GW) triggers involving at least one neutron star during LIGO/Virgo's third observing run (O3). We searched binary neutron star (BNS) and neutron star black hole (NSBH) merger localizations with the Zwicky Transient Facility (ZTF) and undertook follow-up with the Global Relay of Observatories Watching Transients Happen (GROWTH) collaboration. The GW triggers had a median localization area of 4480 deg(2), a median distance of 267 Mpc, and false-alarm rates ranging from 1.5 to 10(-25) yr(-1). The ZTF coverage in the g and r bands had a median enclosed probability of 39%, median depth of 20.8 mag, and median time lag between merger and the start of observations of 1.5 hr. The O3 follow-up by the GROWTH team comprised 340 UltraViolet/Optical/InfraRed (UVOIR) photometric points, 64 OIR spectra, and three radio images using 17 different telescopes. We find no promising kilonovae (radioactivity-powered counterparts), and we show how to convert the upper limits to constrain the underlying kilonova luminosity function. Initially, we assume that all GW triggers are bona fide astrophysical events regardless of false-alarm rate and that kilonovae accompanying BNS and NSBH mergers are drawn from a common population; later, we relax these assumptions. Assuming that all kilonovae are at least as luminous as the discovery magnitude of GW170817 (-16.1 mag), we calculate that our joint probability of detecting zero kilonovae is only 4.2%. If we assume that all kilonovae are brighter than -16.6 mag (the extrapolated peak magnitude of GW170817) and fade at a rate of 1 mag day(-1) (similar to GW170817), the joint probability of zero detections is 7%. If we separate the NSBH and BNS populations based on the online classifications, the joint probability of zero detections, assuming all kilonovae are brighter than -16.6 mag, is 9.7% for NSBH and 7.9% for BNS mergers. Moreover, no more than <57% (<89%) of putative kilonovae could be brighter than -16.6 mag assuming flat evolution (fading by 1 mag day(-1)) at the 90% confidence level. If we further take into account the online terrestrial probability for each GW trigger, we find that no more than <68% of putative kilonovae could be brighter than -16.6 mag. Comparing to model grids, we find that some kilonovae must have M-ej M, X-lan > 10(-4), or > 30 degrees to be consistent with our limits. We look forward to searches in the fourth GW observing run; even 17 neutron star mergers with only 50% coverage to a depth of -16 mag would constrain the maximum fraction of bright kilonovae to <25%.
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| 9. |
- Kilarski, Laura L., et al.
(författare)
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Meta-analysis in more than 17,900 cases of ischemic stroke reveals a novel association at 12q24.12
- 2014
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Ingår i: Neurology. - 1526-632X .- 0028-3878. ; 83:8, s. 678-685
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To perform a genome-wide association study (GWAS) using the Immunochip array in 3,420 cases of ischemic stroke and 6,821 controls, followed by a meta-analysis with data from more than 14,000 additional ischemic stroke cases. Methods: Using the Immunochip, we genotyped 3,420 ischemic stroke cases and 6,821 controls. After imputation we meta-analyzed the results with imputed GWAS data from 3,548 cases and 5,972 controls recruited from the ischemic stroke WTCCC2 study, and with summary statistics from a further 8,480 cases and 56,032 controls in the METASTROKE consortium. A final in silico "look-up" of 2 single nucleotide polymorphisms in 2,522 cases and 1,899 controls was performed. Associations were also examined in 1,088 cases with intracerebral hemorrhage and 1,102 controls. Results: In an overall analysis of 17,970 cases of ischemic stroke and 70,764 controls, we identified a novel association on chromosome 12q24 (rs10744777, odds ratio [OR] 1.10 [1.07-1.13], p = 7.12 x 10(-11)) with ischemic stroke. The association was with all ischemic stroke rather than an individual stroke subtype, with similar effect sizes seen in different stroke subtypes. There was no association with intracerebral hemorrhage (OR 1.03 [0.90-1.17], p = 0.695). Conclusion: Our results show, for the first time, a genetic risk locus associated with ischemic stroke as a whole, rather than in a subtype-specific manner. This finding was not associated with intracerebral hemorrhage.
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| 10. |
- Soumagnac, Maayane T., et al.
(författare)
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Early Ultraviolet Observations of Type IIn Supernovae Constrain the Asphericity of Their Circumstellar Material
- 2020
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 899:1
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Tidskriftsartikel (refereegranskat)abstract
- We present a survey of the early evolution of 12 Type IIn supernovae (SNe IIn) at ultraviolet and visible light wavelengths. We use this survey to constrain the geometry of the circumstellar material (CSM) surrounding SN IIn explosions, which may shed light on their progenitor diversity. In order to distinguish between aspherical and spherical CSM, we estimate the blackbody radius temporal evolution of the SNe IIn of our sample, following the method introduced by Soumagnac et al. We find that higher-luminosity objects tend to show evidence for aspherical CSM. Depending on whether this correlation is due to physical reasons or to some selection bias, we derive a lower limit between 35% and 66% for the fraction of SNe IIn showing evidence for aspherical CSM. This result suggests that asphericity of the CSM surrounding SNe IIn is common-consistent with data from resolved images of stars undergoing considerable mass loss. It should be taken into account for more realistic modeling of these events.
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| 11. |
- Traylor, Matthew, et al.
(författare)
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A Novel MMP12 Locus Is Associated with Large Artery Atherosclerotic Stroke Using a Genome-Wide Age-at-Onset Informed Approach.
- 2014
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Ingår i: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 10:7
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Tidskriftsartikel (refereegranskat)abstract
- Genome-wide association studies (GWAS) have begun to identify the common genetic component to ischaemic stroke (IS). However, IS has considerable phenotypic heterogeneity. Where clinical covariates explain a large fraction of disease risk, covariate informed designs can increase power to detect associations. As prevalence rates in IS are markedly affected by age, and younger onset cases may have higher genetic predisposition, we investigated whether an age-at-onset informed approach could detect novel associations with IS and its subtypes; cardioembolic (CE), large artery atherosclerosis (LAA) and small vessel disease (SVD) in 6,778 cases of European ancestry and 12,095 ancestry-matched controls. Regression analysis to identify SNP associations was performed on posterior liabilities after conditioning on age-at-onset and affection status. We sought further evidence of an association with LAA in 1,881 cases and 50,817 controls, and examined mRNA expression levels of the nearby genes in atherosclerotic carotid artery plaques. Secondly, we performed permutation analyses to evaluate the extent to which age-at-onset informed analysis improves significance for novel loci. We identified a novel association with an MMP12 locus in LAA (rs660599; p = 2.5×10-7), with independent replication in a second population (p = 0.0048, OR(95% CI) = 1.18(1.05-1.32); meta-analysis p = 2.6×10-8). The nearby gene, MMP12, was significantly overexpressed in carotid plaques compared to atherosclerosis-free control arteries (p = 1.2×10-15; fold change = 335.6). Permutation analyses demonstrated improved significance for associations when accounting for age-at-onset in all four stroke phenotypes (p<0.001). Our results show that a covariate-informed design, by adjusting for age-at-onset of stroke, can detect variants not identified by conventional GWAS.
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| 12. |
- Zhou, Wei, et al.
(författare)
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Global Biobank Meta-analysis Initiative : Powering genetic discovery across human disease
- 2022
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Ingår i: Cell Genomics. - : Elsevier. - 2666-979X. ; 2:10
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Tidskriftsartikel (refereegranskat)abstract
- Biobanks facilitate genome-wide association studies (GWASs), which have mapped genomic loci across a range of human diseases and traits. However, most biobanks are primarily composed of individuals of European ancestry. We introduce the Global Biobank Meta-analysis Initiative (GBMI)-a collaborative network of 23 biobanks from 4 continents representing more than 2.2 million consented individuals with genetic data linked to electronic health records. GBMI meta-analyzes summary statistics from GWASs generated using harmonized genotypes and phenotypes from member biobanks for 14 exemplar diseases and endpoints. This strategy validates that GWASs conducted in diverse biobanks can be integrated despite heterogeneity in case definitions, recruitment strategies, and baseline characteristics. This collaborative effort improves GWAS power for diseases, benefits understudied diseases, and improves risk prediction while also enabling the nomination of disease genes and drug candidates by incorporating gene and protein expression data and providing insight into the underlying biology of human diseases and traits.
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| 13. |
- Abbafati, Cristiana, et al.
(författare)
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- 2020
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Tidskriftsartikel (refereegranskat)
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| 14. |
- Andreoni, Igor, et al.
(författare)
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Fast-transient Searches in Real Time with ZTFReST : Identification of Three Optically Discovered Gamma-Ray Burst Afterglows and New Constraints on the Kilonova Rate
- 2021
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 918:2
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Tidskriftsartikel (refereegranskat)abstract
- The most common way to discover extragalactic fast transients, which fade within a few nights in the optical, is via follow-up of gamma-ray burst and gravitational-wave triggers. However, wide-field surveys have the potential to identify rapidly fading transients independently of such external triggers. The volumetric survey speed of the Zwicky Transient Facility (ZTF) makes it sensitive to objects as faint and fast fading as kilonovae, the optical counterparts to binary neutron star mergers, out to almost 200 Mpc. We introduce an open-source software infrastructure, the ZTF REaltime Search and Triggering, ZTFReST, designed to identify kilonovae and fast transients in ZTF data. Using the ZTF alert stream combined with forced point-spread-function photometry, we have implemented automated candidate ranking based on their photometric evolution and fitting to kilonova models. Automated triggering, with a human in the loop for monitoring, of follow-up systems has also been implemented. In 13 months of science validation, we found several extragalactic fast transients independently of any external trigger, including two supernovae with post-shock cooling emission, two known afterglows with an associated gamma-ray burst (ZTF20abbiixp, ZTF20abwysqy), two known afterglows without any known gamma-ray counterpart (ZTF20aajnksq, ZTF21aaeyldq), and three new fast-declining sources (ZTF20abtxwfx, ZTF20acozryr, ZTF21aagwbjr) that are likely associated with GRB200817A, GRB201103B, and GRB210204A. However, we have not found any objects that appear to be kilonovae. We constrain the rate of GW170817-like kilonovae to R < 900 Gpc(-3) yr(-1) (95% confidence). A framework such as ZTFReST could become a prime tool for kilonova and fast-transient discovery with the Vera Rubin Observatory.
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| 15. |
- Bellm, Eric C., et al.
(författare)
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The Zwicky Transient Facility : Surveys and Scheduler
- 2019
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Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 131:1000
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Tidskriftsartikel (refereegranskat)abstract
- We present a novel algorithm for scheduling the observations of time-domain imaging surveys. Our integer linear programming approach optimizes an observing plan for an entire night by assigning targets to temporal blocks, enabling strict control of the number of exposures obtained per field and minimizing filter changes. A subsequent optimization step minimizes slew times between each observation. Our optimization metric self-consistently weights contributions from time-varying airmass, seeing, and sky brightness to maximize the transient discovery rate. We describe the implementation of this algorithm on the surveys of the Zwicky Transient Facility and present its on-sky performance.
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| 16. |
- Bellm, Eric C., et al.
(författare)
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The Zwicky Transient Facility : System Overview, Performance, and First Results
- 2019
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Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 131:995
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Tidskriftsartikel (refereegranskat)abstract
- The Zwicky Transient Facility (ZTF) is a new optical time-domain survey that uses the Palomar 48 inch Schmidt telescope. A custom-built wide-field camera provides a 47 deg(2) field of view and 8 s readout time, yielding more than an order of magnitude improvement in survey speed relative to its predecessor survey, the Palomar Transient Factory. We describe the design and implementation of the camera and observing system. The ZTF data system at the Infrared Processing and Analysis Center provides near-real-time reduction to identify moving and varying objects. We outline the analysis pipelines, data products, and associated archive. Finally, we present on-sky performance analysis and first scientific results from commissioning and the early survey. ZTF's public alert stream will serve as a useful precursor for that of the Large Synoptic Survey Telescope.
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| 17. |
- Bolin, Bryce T., et al.
(författare)
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Characterization of the Nucleus, Morphology, and Activity of Interstellar Comet 2I/Borisov by Optical and Near-infrared GROWTH, Apache Point, IRTF, ZTF, and Keck Observations
- 2020
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 160:1
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Tidskriftsartikel (refereegranskat)abstract
- We present visible and near-infrared (NIR) photometric and spectroscopic observations of interstellar object (ISO) 2I/Borisov taken from 2019 September 10 to 2019 December 20 using the GROWTH, the Apache Point Observatory Astrophysical Research Consortium 3.5 m, and the NASA Infrared Telescope Facility 3.0 m combined with pre- and postdiscovery observations of 2I obtained by the Zwicky Transient Facility from 2019 March 17 to 2019 May 5. Comparison with imaging of distant solar system comets shows an object very similar to mildly active solar system comets with an outgassing rate of similar to 10(27)mol s(-1). The photometry, taken in filters spanning the visible and NIR range, shows a gradual brightening trend of similar to 0.03 mag day(-1)since 2019 September 10 UTC for a reddish object becoming neutral in the NIR. The light curve from recent and prediscovery data reveals a brightness trend suggesting the recent onset of significant H2O sublimation with the comet being active with super volatiles such as CO at heliocentric distances >6 au consistent with its extended morphology. Using the advanced capability to significantly reduce the scattered light from the coma enabled by high-resolution NIR images from Keck adaptive optics taken on 2019 October 4, we estimate a diameter for 2I's nucleus of less than or similar to 1.4 km. We use the size estimates of 1I/'Oumuamua and 2I/Borisov to roughly estimate the slope of the ISO size distribution, resulting in a slope of similar to 3.4 1.2, similar to solar system comets and bodies produced from collisional equilibrium.
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| 18. |
- Bruch, Rachel J., et al.
(författare)
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A Large Fraction of Hydrogen-rich Supernova Progenitors Experience Elevated Mass Loss Shortly Prior to Explosion
- 2021
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 912:1
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Tidskriftsartikel (refereegranskat)abstract
- Spectroscopic detection of narrow emission lines traces the presence of circumstellar mass distributions around massive stars exploding as core-collapse supernovae. Transient emission lines disappearing shortly after the supernova explosion suggest that the material spatial extent is compact and implies an increased mass loss shortly prior to explosion. Here, we present a systematic survey for such transient emission lines (Flash Spectroscopy) among Type II supernovae detected in the first year of the Zwicky Transient Facility survey. We find that at least six out of ten events for which a spectrum was obtained within two days of the estimated explosion time show evidence for such transient flash lines. Our measured flash event fraction (>30% at 95% confidence level) indicates that elevated mass loss is a common process occurring in massive stars that are about to explode as supernovae.
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| 19. |
- Bruch, Rachel J., et al.
(författare)
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The Prevalence and Influence of Circumstellar Material around Hydrogen-rich Supernova Progenitors
- 2023
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 952:2
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Tidskriftsartikel (refereegranskat)abstract
- Narrow transient emission lines (flash-ionization features) in early supernova (SN) spectra trace the presence of circumstellar material (CSM) around the massive progenitor stars of core-collapse SNe. The lines disappear within days after the SN explosion, suggesting that this material is spatially confined, and originates from enhanced mass loss shortly (months to a few years) prior to the explosion. We performed a systematic survey of H-rich (Type II) SNe discovered within less than 2 days from the explosion during the first phase of the Zwicky Transient Facility survey (2018–2020), finding 30 events for which a first spectrum was obtained within <2 days from the explosion. The measured fraction of events showing flash-ionization features (>36% at the 95% confidence level) confirms that elevated mass loss in massive stars prior to SN explosion is common. We find that SNe II showing flash-ionization features are not significantly brighter, nor bluer, nor more slowly rising than those without. This implies that CSM interaction does not contribute significantly to their early continuum emission, and that the CSM is likely optically thin. We measured the persistence duration of flash-ionization emission and find that most SNe show flash features for ≈5 days. Rarer events, with persistence timescales >10 days, are brighter and rise longer, suggesting these may be intermediate between regular SNe II and strongly interacting SNe IIn.
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| 20. |
- Coughlin, Michael W., et al.
(författare)
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2900 Square Degree Search for the Optical Counterpart of Short Gamma-Ray Burst GRB 180523B with the Zwicky Transient Facility
- 2019
-
Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 131:998
-
Tidskriftsartikel (refereegranskat)abstract
- There is significant interest in the models for production of short gamma-ray bursts (GRBs). Until now, the number of known short GRBs with multi-wavelength afterglows has been small. While the Fermi GRB Monitor detects many GRBs relative to the Neil Gehrels Swift Observatory, the large localization regions makes the search for counterparts difficult. With the Zwicky Transient Facility (ZTF) recently achieving first light, it is now fruitful to use its combination of depth (m(AB) similar to 20.6), field of view (approximate to 47 square degrees), and survey cadence (every similar to 3 days) to perform Target of Opportunity observations. We demonstrate this capability on GRB 180523B, which was recently announced by the Fermi GRB Monitor as a short GRB. ZTF imaged approximate to 2900 square degrees of the localization region, resulting in the coverage of 61.6% of the enclosed probability over two nights to a depth of m(AB) similar to 20.5. We characterized 14 previously unidentified transients, and none were found to be consistent with a short GRB counterpart. This search with the ZTF shows it is an efficient camera for searching for coarsely localized short GRB and gravitational-wave counterparts, allowing for a sensitive search with minimal interruption to its nominal cadence.
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| 21. |
- Evans, Luke Christopher, et al.
(författare)
-
Behavioural modes in butterflies : their implications for movement and searching behaviour
- 2020
-
Ingår i: Animal Behaviour. - : Elsevier BV. - 0003-3472. ; 169, s. 23-33
-
Tidskriftsartikel (refereegranskat)abstract
- Animals move in ‘modes’ where movement patterns relate to specific behaviours. Despite much work on the movement of butterflies, their behavioural modes are relatively unexplored. Here we analysed the behaviour of the model butterfly species the meadow brown, Maniola jurtina. We identified modes in both sexes and across habitats varying in resource density. We found that, in nectar-rich habitats, males had more diverse behaviour than females, engaging in a unique ‘high-flight’ mode associated with mate search, whereas females were primarily nectaring or inactive. In nectar-poor habitats, both sexes were similar, switching between flight and inactivity. We also identified the movement parameters of the modes, finding that, for both sexes, movements associated with nectaring were slower and more tortuous and, for males, the mode associated with mate searching was straighter and faster. Using an individual-based random-walk model, we investigated the effects of behaviour on movement predictions by comparing a mode-switching model with a version including intraspecific variation and another assuming homogeneity between individuals. For both sexes, including modes affected the mean and shape of the displacement rate compared to models assuming homogeneity, although for females modes increased displacement 1.5 times while for males they decreased it by a third. Both models also differed substantially from models assuming intraspecific variation. Finally, using a new model of search behaviour we investigated the general conditions under which individuals should engage in an exclusive search for host plants or receptive females. Parameterized for M. jurtina, the model predicted males should engage exclusively in mate search, but females only when searching is very efficient. The model provides a framework for analysing the searching behaviour of other butterfly species.
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| 22. |
- Frederick, Sara, et al.
(författare)
-
A Family Tree of Optical Transients from Narrow-line Seyfert 1 Galaxies
- 2021
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 920:1
-
Tidskriftsartikel (refereegranskat)abstract
- The Zwicky Transient Facility (ZTF) has discovered five events (0.01 < z < 0.4) belonging to an emerging class of active galactic nuclei (AGNs) undergoing smooth, large-amplitude, and rapidly rising flares. This sample consists of several transients initially classified as supernovae with narrow spectral lines. However, upon closer inspection, all of the host galaxies display Balmer lines with FWHM(H beta) similar to 900-1400 km s(-1), characteristic of a narrow-line Seyfert 1 (NLSy1) galaxy. The transient events are long lived, over 400 days on average in the observed frame. We report UV and X-ray follow-up of the flares and observe persistent UV emission, with two of the five transients detected with luminous X-ray emission, ruling out a supernova interpretation. We compare the properties of this sample to previously reported flaring NLSy1 galaxies and find that they fall into three spectroscopic categories: 1) Balmer line profiles and Fe ii complexes typical of NLSy1s, 2) strong He ii profiles, and 3) He ii profiles including Bowen fluorescence features. The latter are members of the growing class of AGN flares attributed to enhanced accretion reported by Trakhtenbrot et al. We consider physical interpretations in the context of related transients from the literature. For example, two of the sources show high-amplitude rebrightening in the optical, ruling out a simple tidal disruption event scenario for those transients. We conclude that three of the sample belong to the Trakhtenbrot et al. class and two are tidal disruption events in NLSy1s. We also hypothesize as to why NLSy1s are preferentially the sites of such rapid enhanced flaring activity.
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| 23. |
- Frederick, Sara, et al.
(författare)
-
A New Class of Changing-look LINERs
- 2019
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 883:1
-
Tidskriftsartikel (refereegranskat)abstract
- We report the discovery of six active galactic nuclei (AGNs) caught turning on during the first nine months of the Zwicky Transient Facility (ZTF) survey. The host galaxies were classified as low-ionization nuclear emissionline region galaxies (LINERs) by weak narrow forbidden line emission in their archival SDSS spectra, and detected by ZTF as nuclear transients. In five of the cases, we found via follow-up spectroscopy that they had transformed into broad-line AGNs, reminiscent of the changing-look LINER iPTF16bco. In one case, ZTF18aajupnt/ AT2018dyk, follow-up Hubble Space Telescope ultraviolet and ground-based optical spectra revealed the transformation into a narrow-line Seyfert 1 with strong [Fe VII, X, XIV] and He II lambda 4686 coronal lines. Swift monitoring observations of this source reveal bright UV emission that tracks the optical flare, accompanied by a luminous soft X-ray flare that peaks similar to 60 days later. Spitzer follow-up observations also detect a luminous midinfrared flare, implying a large covering fraction of dust. Archival light curves of the entire sample from CRTS, ATLAS, and ASAS-SN constrain the onset of the optical nuclear flaring from a prolonged quiescent state. Here we present the systematic selection and follow-up of this new class of changing-look LINERs, compare their properties to previously reported changing-look Seyfert galaxies, and conclude that they are a unique class of transients well-suited to test the uncertain physical processes associated with the LINER accretion state.
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| 24. |
- Fremling, Christoffer, et al.
(författare)
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SNIascore : Deep-learning Classification of Low-resolution Supernova Spectra
- 2021
-
Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 917:1
-
Tidskriftsartikel (refereegranskat)abstract
- We present SNIascore, a deep-learning-based method for spectroscopic classification of thermonuclear supernovae (SNe Ia) based on very low-resolution (R similar to 100) data. The goal of SNIascore is the fully automated classification of SNe Ia with a very low false-positive rate (FPR) so that human intervention can be greatly reduced in large-scale SN classification efforts, such as that undertaken by the public Zwicky Transient Facility (ZTF) Bright Transient Survey (BTS). We utilize a recurrent neural network architecture with a combination of bidirectional long short-term memory and gated recurrent unit layers. SNIascore achieves a SNIascore simultaneously performs binary classification and predicts the redshifts of secure SNe Ia via regression (with a typical uncertainty of z = 0.01 to z = 0.12). For the magnitude-limited ZTF BTS survey (approximate to 70% SNe Ia), deploying SNIascore reduces the amount of spectra in need of human classification or confirmation by approximate to 60%. Furthermore, SNIascore allows SN Ia classifications to be automatically announced in real time to the public immediately following a finished observation during the night.
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| 25. |
- Heid, Iris M, et al.
(författare)
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Meta-analysis identifies 13 new loci associated with waist-hip ratio and reveals sexual dimorphism in the genetic basis of fat distribution
- 2010
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 42:11, s. 949-960
-
Tidskriftsartikel (refereegranskat)abstract
- Waist-hip ratio (WHR) is a measure of body fat distribution and a predictor of metabolic consequences independent of overall adiposity. WHR is heritable, but few genetic variants influencing this trait have been identified. We conducted a meta-analysis of 32 genome-wide association studies for WHR adjusted for body mass index (comprising up to 77,167 participants), following up 16 loci in an additional 29 studies (comprising up to 113,636 subjects). We identified 13 new loci in or near RSPO3, VEGFA, TBX15-WARS2, NFE2L3, GRB14, DNM3-PIGC, ITPR2-SSPN, LY86, HOXC13, ADAMTS9, ZNRF3-KREMEN1, NISCH-STAB1 and CPEB4 (P = 1.9 × 10⁻⁹ to P = 1.8 × 10⁻⁴⁰) and the known signal at LYPLAL1. Seven of these loci exhibited marked sexual dimorphism, all with a stronger effect on WHR in women than men (P for sex difference = 1.9 × 10⁻³ to P = 1.2 × 10⁻¹³). These findings provide evidence for multiple loci that modulate body fat distribution independent of overall adiposity and reveal strong gene-by-sex interactions.
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| 26. |
- Ho, Anna Y. Q., et al.
(författare)
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Evidence for Late-stage Eruptive Mass Loss in the Progenitor to SN2018gep, a Broad-lined Ic Supernova : Pre-explosion Emission and a Rapidly Rising Luminous Transient
- 2019
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 887:2
-
Tidskriftsartikel (refereegranskat)abstract
- We present detailed observations of ZTF18abukavn (SN2018gep), discovered in high-cadence data from the Zwicky Transient Facility as a rapidly rising (1.4 +/- 0.1 mag hr(-1)) and luminous (M-g,M- peak = -20 mag) transient. It is spectroscopically classified as a broad-lined stripped-envelope supernova (Ic-BL SN). The high peak luminosity (L-bol greater than or similar to 3 x 10(44) erg s(-1)), the short rise time (t(rise) = 3 days in g band), and the blue colors at peak (g-r similar to -0.4) all resemble the high-redshift Ic-BL iPTF16asu, as well as several other unclassified fast transients. The early discovery of SN2018gep (within an hour of shock breakout) enabled an intensive spectroscopic campaign, including the highest-temperature (T-eff greater than or similar to 40,000 K) spectra of a stripped-envelope SN. A retrospective search revealed luminous (M-g similar to M-r approximate to -14 mag) emission in the days to weeks before explosion, the first definitive detection of precursor emission for a Ic-BL. We find a limit on the isotropic gamma-ray energy release E-gamma,E- iso < 4.9 x 10(48) erg, a limit on X-ray emission L-X < 10(40) erg s(-1), and a limit on radio emission nu L-v less than or similar to 10(37) erg s(-1). Taken together, we find that the early (< 10 days) data are best explained by shock breakout in a massive shell of dense circumstellar material (0.02 M-circle dot) at large radii (3 x 10(14) cm) that was ejected in eruptive pre-explosion mass-loss episodes. The late-time (> 10 days) light curve requires an additional energy source, which could be the radioactive decay of Ni-56.
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| 27. |
- House, Robert A., et al.
(författare)
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Superstructure control of first-cycle voltage hysteresis in oxygen-redox cathodes
- 2020
-
Ingår i: Nature. - : NATURE PUBLISHING GROUP. - 0028-0836 .- 1476-4687. ; 577:7791, s. 502-508
-
Tidskriftsartikel (refereegranskat)abstract
- In conventional intercalation cathodes, alkali metal ions can move in and out of a layered material with the charge being compensated for by reversible reduction and oxidation of the transition metal ions. If the cathode material used in a lithium-ion or sodium-ion battery is alkali-rich, this can increase the battery's energy density by storing charge on the oxide and the transition metal ions, rather than on the transition metal alone(1-10). There is a high voltage associated with oxidation of O2- during the first charge, but this is not recovered on discharge, resulting in reduced energy density(11). Displacement of transition metal ions into the alkali metal layers has been proposed to explain the first-cycle voltage loss (hysteresis)(9,12-16). By comparing two closely related intercalation cathodes, Na-0.75[Li0.25Mn0.75]O-2 and Na-0.6[Li0.2Mn0.8]O-2, here we show that the first-cycle voltage hysteresis is determined by the superstructure in the cathode, specifically the local ordering of lithium and transition metal ions in the transition metal layers. The honeycomb superstructure of Na-0.75[Li0.25Mn0.75]O-2, present in almost all oxygen-redox compounds, is lost on charging, driven in part by formation of molecular O-2 inside the solid. The O-2 molecules are cleaved on discharge, reforming O2-, but the manganese ions have migrated within the plane, changing the coordination around O2- and lowering the voltage on discharge. The ribbon superstructure in Na-0.6[Li0.2Mn0.8]O-2 inhibits manganese disorder and hence O-2 formation, suppressing hysteresis and promoting stable electron holes on O2- that are revealed by X-ray absorption spectroscopy. The results show that voltage hysteresis can be avoided in oxygen-redox cathodes by forming materials with a ribbon superstructure in the transition metal layers that suppresses migration of the transition metal. In oxygen-redox intercalation cathodes, voltage hysteresis can be avoided by forming cathode materials with a 'ribbon' superstructure in the transition metal layers that suppresses transition metal migration.
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| 28. |
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| 29. |
- Jowett, Geraldine M., et al.
(författare)
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ILC1 drive intestinal epithelial and matrix remodelling
- 2021
-
Ingår i: Nature Materials. - : Springer Nature. - 1476-1122 .- 1476-4660. ; 20:2, s. 250-259
-
Tidskriftsartikel (refereegranskat)abstract
- Organoids can shed light on the dynamic interplay between complex tissues and rare cell types within a controlled microenvironment. Here, we develop gut organoid cocultures with type-1 innate lymphoid cells (ILC1) to dissect the impact of their accumulation in inflamed intestines. We demonstrate that murine and human ILC1 secrete transforming growth factor β1, driving expansion of CD44v6+ epithelial crypts. ILC1 additionally express MMP9 and drive gene signatures indicative of extracellular matrix remodelling. We therefore encapsulated human epithelial–mesenchymal intestinal organoids in MMP-sensitive, synthetic hydrogels designed to form efficient networks at low polymer concentrations. Harnessing this defined system, we demonstrate that ILC1 drive matrix softening and stiffening, which we suggest occurs through balanced matrix degradation and deposition. Our platform enabled us to elucidate previously undescribed interactions between ILC1 and their microenvironment, which suggest that they may exacerbate fibrosis and tumour growth when enriched in inflamed patient tissues.
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| 30. |
- Karambelkar, Viraj R., et al.
(författare)
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Faintest of Them All : ZTF 21aaoryiz/SN 2021fcg-Discovery of an Extremely Low Luminosity Type Iax Supernova
- 2021
-
Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 921:1
-
Tidskriftsartikel (refereegranskat)abstract
- We present the discovery of ZTF 21aaoryiz/SN 2021fcg-an extremely low luminosity Type Tax supernova. SN 2021fcg was discovered by the Zwicky Transient Facility in the star-forming galaxy IC0512 at a distance of approximate to 27 Mpc. It reached a peak absolute magnitude of M-r = -12.66 +/- 0.20 mag, making it the least luminous thermonuclear supernova discovered to date. The E(B - V) contribution from the underlying host galaxy is unconstrained. However, even if it were as large as 0.5 mag, the peak absolute magnitude would be M-r = -13.78 +/- 0.20 mag-still consistent with being the lowest-luminosity SN. Optical spectra of SN 2021fcg taken at 37 and 65 days post-maximum show strong [Ca II], Ca II, and Na I D emission and several weak [Fe II] emission lines. The [Ca II] emission in the two spectra has extremely low velocities of approximate to 1300 and 1000 km s(-1), respectively. The spectra very closely resemble those of the very low luminosity Type Tax supernovae SN 2008 ha, SN 2010ae, and SN 2019gsc taken at similar phases. The peak bolometric luminosity of SN 2021fcg is approximate to 2.5(-0.3)(+1.5) x 10(40) erg s(-1), which is a factor of 3 lower than that for SN 2008 ha. The bolometric lightcurve of SN 2021fcg is consistent with a very low ejected nickel mass (M-Ni approximate to 0.8(-0.5)(+0.4) x 10(-3) M-circle dot). The low luminosity and nickel mass of SN 2021fcg pose a challenge to the picture that low-luminosity SNe Tax originate from deflagrations of near-M-ch hybrid carbon-oxygen-neon white dwarfs. Instead, the merger of a carbon-oxygen and oxygen-neon white dwarf is a promising model to explain SN 2021fcg.
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| 31. |
- Kirsch, Irving, et al.
(författare)
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Definitions of Hypnosis and Hypnotizability and their Relation to Suggestion and Suggestibility : A Consensus Statement
- 2011
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Ingår i: Contemporary Hypnosis & Integrative Therapy. - : Crown House Publishing. - 2049-2146. ; 28, s. 107-115
-
Tidskriftsartikel (refereegranskat)abstract
- This article reports a consensus that was reached at an Advanced Workshop in Experimental Hypnosis held as part of the joint annual conference of the British Society of Medical and Dental Hypnosis (BSMDH) and the British Society of Experimental and Clinical Hypnosis (BSECH). The unanimous consensus was that conventional definitions of hypnosis and hypnotizability are logically inconsistent and that at least one of them needed to be changed. Participants were divided between the alternatives of (1) broadening the operational definition of hypnosis so as to include responding to so-called waking suggestion and (2) limiting the term 'hypnotizability' to the effects of administering a hypnotic induction.
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| 32. |
- Kupfer, Thomas, et al.
(författare)
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Year 1 of the ZTF high-cadence Galactic plane survey : strategy, goals, and early results on new single-mode hot subdwarf B-star pulsatos
- 2021
-
Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 505:1, s. 1254-1267
-
Tidskriftsartikel (refereegranskat)abstract
- We present the goals, strategy, and first results of the high-cadence Galactic plane survey using the Zwicky Transient Facility (ZTF). The goal of the survey is to unveil the Galactic population of short-period variable stars, including short-period binaries, and stellar pulsators with periods less than a few hours. Between 2018 June and 2019 January, we observed 64 ZTF fields resulting in 2990 deg2 of high stellar density in the ZTF-r band along the Galactic plane. Each field was observed continuously for 1.5 to 6 h with a cadence of 40 sec. Most fields have between 200 and 400 observations obtained over 2–3 continuous nights. As part of this survey, we extract a total of ≈230 million individual objects with at least 80 epochs obtained during the high-cadence Galactic plane survey reaching an average depth of ZTF–r ≈ 20.5 mag. For four selected fields with 2–10 million individual objects per field, we calculate different variability statistics and find that ≈1–2 per cent of the objects are astrophysically variable over the observed period. We present a progress report on recent discoveries, including a new class of compact pulsators, the first members of a new class of Roche lobe filling hot subdwarf binaries as well as new ultracompact double white dwarfs and flaring stars. Finally, we present a sample of 12 new single-mode hot subdwarf B-star pulsators with pulsation amplitudes between ZTF–r = 20–76 mmag and pulsation periods between P = 5.8–16 min with a strong cluster of systems with periods ≈6 min. All of the data have now been released in either ZTF Data Release 3 or Data Release 4.
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| 33. |
- Lango Allen, Hana, et al.
(författare)
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Hundreds of variants clustered in genomic loci and biological pathways affect human height.
- 2010
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 467:7317, s. 832-8
-
Tidskriftsartikel (refereegranskat)abstract
- Most common human traits and diseases have a polygenic pattern of inheritance: DNA sequence variants at many genetic loci influence the phenotype. Genome-wide association (GWA) studies have identified more than 600 variants associated with human traits, but these typically explain small fractions of phenotypic variation, raising questions about the use of further studies. Here, using 183,727 individuals, we show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait. The large number of loci reveals patterns with important implications for genetic studies of common human diseases and traits. First, the 180 loci are not random, but instead are enriched for genes that are connected in biological pathways (P = 0.016) and that underlie skeletal growth defects (P<0.001). Second, the likely causal gene is often located near the most strongly associated variant: in 13 of 21 loci containing a known skeletal growth gene, that gene was closest to the associated variant. Third, at least 19 loci have multiple independently associated variants, suggesting that allelic heterogeneity is a frequent feature of polygenic traits, that comprehensive explorations of already-discovered loci should discover additional variants and that an appreciable fraction of associated loci may have been identified. Fourth, associated variants are enriched for likely functional effects on genes, being over-represented among variants that alter amino-acid structure of proteins and expression levels of nearby genes. Our data explain approximately 10% of the phenotypic variation in height, and we estimate that unidentified common variants of similar effect sizes would increase this figure to approximately 16% of phenotypic variation (approximately 20% of heritable variation). Although additional approaches are needed to dissect the genetic architecture of polygenic human traits fully, our findings indicate that GWA studies can identify large numbers of loci that implicate biologically relevant genes and pathways.
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| 34. |
- Lee, James J, et al.
(författare)
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Gene discovery and polygenic prediction from a genome-wide association study of educational attainment in 1.1 million individuals.
- 2018
-
Ingår i: Nature genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 50:8, s. 1112-1121
-
Tidskriftsartikel (refereegranskat)abstract
- Here we conducted a large-scale genetic association analysis of educational attainment in a sample of approximately 1.1million individuals and identify 1,271independent genome-wide-significant SNPs. For the SNPs taken together, we found evidence of heterogeneous effects across environments. The SNPs implicate genes involved in brain-development processes and neuron-to-neuron communication. In a separate analysis of the X chromosome, we identify 10independent genome-wide-significant SNPs and estimate a SNP heritability of around 0.3% in both men and women, consistent with partial dosage compensation. A joint (multi-phenotype) analysis of educational attainment and three related cognitive phenotypes generates polygenic scores that explain 11-13% of the variance in educational attainment and 7-10% of the variance in cognitive performance. This prediction accuracy substantially increases the utility of polygenic scores as tools in research.
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| 35. |
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| 36. |
- Mahabal, Ashish, et al.
(författare)
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Machine Learning for the Zwicky Transient Facility
- 2019
-
Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 131:997
-
Tidskriftsartikel (refereegranskat)abstract
- The Zwicky Transient Facility is a large optical survey in multiple filters producing hundreds of thousands of transient alerts per night. We describe here various machine learning (ML) implementations and plans to make the maximal use of the large data set by taking advantage of the temporal nature of the data, and further combining it with other data sets. We start with the initial steps of separating bogus candidates from real ones, separating stars and galaxies, and go on to the classification of real objects into various classes. Besides the usual methods (e.g., based on features extracted from light curves) we also describe early plans for alternate methods including the use of domain adaptation, and deep learning. In a similar fashion we describe efforts to detect fast moving asteroids. We also describe the use of the Zooniverse platform for helping with classifications through the creation of training samples, and active learning. Finally we mention the synergistic aspects of ZTF and LSST from the ML perspective.
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| 37. |
- Palmer, Duncan S., et al.
(författare)
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Exome sequencing in bipolar disorder identifies AKAP11 as a risk gene shared with schizophrenia
- 2022
-
Ingår i: Nature Genetics. - : Nature Publishing Group. - 1061-4036 .- 1546-1718. ; 54:5, s. 541-547
-
Tidskriftsartikel (refereegranskat)abstract
- We report results from the Bipolar Exome (BipEx) collaboration analysis of whole-exome sequencing of 13,933 patients with bipolar disorder (BD) matched with 14,422 controls. We find an excess of ultra-rare protein-truncating variants (PTVs) in patients with BD among genes under strong evolutionary constraint in both major BD subtypes. We find enrichment of ultra-rare PTVs within genes implicated from a recent schizophrenia exome meta-analysis (SCHEMA; 24,248 cases and 97,322 controls) and among binding targets of CHD8. Genes implicated from genome-wide association studies (GWASs) of BD, however, are not significantly enriched for ultra-rare PTVs. Combining gene-level results with SCHEMA, AKAP11 emerges as a definitive risk gene (odds ratio (OR) = 7.06, P = 2.83 × 10−9). At the protein level, AKAP-11 interacts with GSK3B, the hypothesized target of lithium, a primary treatment for BD. Our results lend support to BD’s polygenicity, demonstrating a role for rare coding variation as a significant risk factor in BD etiology.
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| 38. |
- Patterson, Kurt, et al.
(författare)
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Nitrate-regulated glutaredoxins control Arabidopsis thaliana primary root growth.
- 2016
-
Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 1532-2548 .- 0032-0889. ; , s. 989-999
-
Tidskriftsartikel (refereegranskat)abstract
- Nitrogen is an essential soil nutrient for plants, and lack of nitrogen commonly limits plant growth. Soil nitrogen is typically available to plants in two inorganic forms: nitrate and ammonium. To better understand how nitrate and ammonium differentially affect plant metabolism and development, we performed transcriptional profiling of the shoots of ammonium-supplied and nitrate-supplied Arabidopsis thaliana plants. Seven genes encoding class III glutaredoxins were found to be strongly and specifically induced by nitrate. RNA silencing of four of these glutaredoxin genes (AtGRXS3/4/5/8) resulted in plants with increased primary root length (~25% longer than wild-type) and decreased sensitivity to nitrate-mediated inhibition of primary root growth. Increased primary root growth is also a well-characterized phenotype of many cytokinin-deficient plant lines. We determined that nitrate induction of glutaredoxin gene expression was dependent upon cytokinin signaling and that cytokinins could activate glutaredoxin gene expression independent of plant nitrate status. In addition, crosses between "long-root" cytokinin-deficient plants and "long-root" glutaredoxin-silenced plants generated hybrids that displayed no further increase in primary root length (i.e. epistasis). Collectively, these findings suggest that AtGRXS3/4/5/8 operate downstream of cytokinins in a signal transduction pathway that negatively regulates plant primary root growth in response to nitrate. This pathway could allow Arabidopsis to actively discriminate between different nitrogen sources in the soil, with the preferred nitrogen source, nitrate, acting to suppress primary root growth (vertical dimension) in concert with its well-characterized stimulatory effect on lateral root growth (horizontal dimension).
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| 39. |
- Perley, Daniel A., et al.
(författare)
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Real-time discovery of AT2020xnd : a fast, luminous ultraviolet transient with minimal radioactive ejecta
- 2021
-
Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 508:4, s. 5138-5147
-
Tidskriftsartikel (refereegranskat)abstract
- The many unusual properties of the enigmatic AT2018cow suggested that at least some subset of the empirical class of fast blue optical transients (FBOTs) represents a genuinely new astrophysical phenomenon. Unfortunately, the intrinsic rarity and fleeting nature of these events have made it difficult to identify additional examples early enough to acquire the observations necessary to constrain theoretical models. We present here the Zwicky Transient Facility discovery of AT2020xnd (ZTF20acigmel, the 'Camel') at z = 0.243, the first unambiguous AT2018cow analogue to be found and confirmed in real time. AT2018cow and AT2020xnd share all key observational properties: a fast optical rise, sustained high photospheric temperature, absence of a second peak attributable to ejection of a radioactively heated stellar envelope, extremely luminous radio, millimetre, and X-ray emission, and a dwarf-galaxy host. This supports the argument that AT2018cow-like events represent a distinct phenomenon from slower-evolving radio-quiet supernovae, likely requiring a different progenitor or a different central engine. The sample properties of the four known members of this class to date disfavour tidal disruption models but are consistent with the alternative model of an accretion powered jet following the direct collapse of a massive star to a black hole. Contextual filtering of alert streams combined with rapid photometric verification using multiband imaging provides an efficient way to identify future members of this class, even at high redshift.
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| 40. |
- Perley, Daniel A., et al.
(författare)
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The Zwicky Transient Facility Bright Transient Survey. II. A Public Statistical Sample for Exploring Supernova Demographics
- 2020
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 904:1
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Tidskriftsartikel (refereegranskat)abstract
- We present a public catalog of transients from the Zwicky Transient Facility (ZTF) Bright Transient Survey, a magnitude-limited (m g or r filter) survey for extragalactic transients in the ZTF public stream. We introduce cuts on survey coverage, sky visibility around peak light, and other properties unconnected to the nature of the transient, and show that the resulting statistical sample is spectroscopically 97% complete at <18 mag, 93% complete at <18.5 mag, and 75% complete at <19 mag. We summarize the fundamental properties of this population, identifying distinct duration-luminosity correlations in a variety of supernova (SN) classes and associating the majority of fast optical transients with well-established spectroscopic SN types (primarily SN Ibn and II/IIb). We measure the Type Ia SN and core-collapse (CC) SN rates and luminosity functions, which show good consistency with recent work. About 7% of CC SNe explode in very low-luminosity galaxies (M-i > -16 mag), 10% in red-sequence galaxies, and 1% in massive ellipticals. We find no significant difference in the luminosity or color distributions between the host galaxies of SNe Type II and SNe Type Ib/c, suggesting that line-driven wind stripping does not play a major role in the loss of the hydrogen envelope from their progenitors. Future large-scale classification efforts with ZTF and other wide-area surveys will provide high-quality measurements of the rates, properties, and environments of all known types of optical transients and limits on the existence of theoretically predicted but as yet unobserved explosions.
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| 41. |
- Purdum, Josiah N., et al.
(författare)
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Time-series and Phase-curve Photometry of the Episodically Active Asteroid (6478) Gault in a Quiescent State Using APO, GROWTH, P200, and ZTF
- 2021
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 911:2
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Tidskriftsartikel (refereegranskat)abstract
- We observed the episodically active asteroid (6478) Gault in 2020 with multiple telescopes in Asia and North America and found that it is no longer active after its recent outbursts at the end of 2018 and the start of 2019. The inactivity during this apparition allowed us to measure the absolute magnitude of Gault of H ( r ) = 14.63 +/- 0.02, G ( r ) = 0.21 +/- 0.02 from our secular phase-curve observations. In addition, we were able to constrain Gault's rotation period using time-series photometric lightcurves taken over 17 hr on multiple days in 2020 August, September, and October. The photometric lightcurves have a repeating less than or similar to 0.05 mag feature suggesting that (6478) Gault has a rotation period of similar to 2.5 hr and may have a semispherical or top-like shape, much like the near-Earth asteroids Ryugu and Bennu. The rotation period of similar to 2.5 hr is near the expected critical rotation period for an asteroid with the physical properties of (6478) Gault, suggesting that its activity observed over multiple epochs is due to surface mass shedding from its fast rotation spin-up by the Yarkovsky-O'Keefe-Radzievskii-Paddack effect.
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| 42. |
- Reusch, Simeon, et al.
(författare)
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Candidate Tidal Disruption Event AT2019fdr Coincident with a High-Energy Neutrino
- 2022
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 128:22
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Tidskriftsartikel (refereegranskat)abstract
- The origins of the high-energy cosmic neutrino flux remain largely unknown. Recently, one high-energy neutrino was associated with a tidal disruption event (TDE). Here we present AT2019fdr, an exceptionally luminous TDE candidate, coincident with another high-energy neutrino. Our observations, including a bright dust echo and soft late-time x-ray emission, further support a TDE origin of this flare. The probability of finding two such bright events by chance is just 0.034%. We evaluate several models for neutrino production and show that AT2019fdr is capable of producing the observed high-energy neutrino, reinforcing the case for TDEs as neutrino sources.
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| 43. |
- Speliotes, Elizabeth K., et al.
(författare)
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Association analyses of 249,796 individuals reveal 18 new loci associated with body mass index
- 2010
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 42:11, s. 937-948
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Tidskriftsartikel (refereegranskat)abstract
- Obesity is globally prevalent and highly heritable, but its underlying genetic factors remain largely elusive. To identify genetic loci for obesity susceptibility, we examined associations between body mass index and ~2.8 million SNPs in up to 123,865 individuals with targeted follow up of 42 SNPs in up to 125,931 additional individuals. We confirmed 14 known obesity susceptibility loci and identified 18 new loci associated with body mass index (P < 5 × 10−8), one of which includes a copy number variant near GPRC5B. Some loci (at MC4R, POMC, SH2B1 and BDNF) map near key hypothalamic regulators of energy balance, and one of these loci is near GIPR, an incretin receptor. Furthermore, genes in other newly associated loci may provide new insights into human body weight regulation.
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| 44. |
- Strotjohann, Nora L., et al.
(författare)
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Bright, Months-long Stellar Outbursts Announce the Explosion of Interaction-powered Supernovae
- 2021
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 907:2
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Tidskriftsartikel (refereegranskat)abstract
- Interaction-powered supernovae (SNe) explode within an optically thick circumstellar medium (CSM) that could be ejected during eruptive events. To identify and characterize such pre-explosion outbursts, we produce forced-photometry light curves for 196 interacting SNe, mostly of Type IIn, detected by the Zwicky Transient Facility between early 2018 and 2020 June. Extensive tests demonstrate that we only expect a few false detections among the 70,000 analyzed pre-explosion images after applying quality cuts and bias corrections. We detect precursor eruptions prior to 18 Type IIn SNe and prior to the Type Ibn SN 2019uo. Precursors become brighter and more frequent in the last months before the SN and month-long outbursts brighter than magnitude -13 occur prior to 25% (5-69%, 95% confidence range) of all Type IIn SNe within the final three months before the explosion. With radiative energies of up to 10(49) erg, precursors could eject similar to 1 M of material. Nevertheless, SNe with detected precursors are not significantly more luminous than other SNe IIn, and the characteristic narrow hydrogen lines in their spectra typically originate from earlier, undetected mass-loss events. The long precursor durations require ongoing energy injection, and they could, for example, be powered by interaction or by a continuum-driven wind. Instabilities during the neon- and oxygen-burning phases are predicted to launch precursors in the final years to months before the explosion; however, the brightest precursor is 100 times more energetic than anticipated.
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| 45. |
- Szkody, Paula, et al.
(författare)
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Cataclysmic Variables in the Second Year of the Zwicky Transient Facility
- 2021
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 162:3
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Tidskriftsartikel (refereegranskat)abstract
- Using a filter in the GROWTH Marshal based on color and the amplitude and timescale of variability, we have identified 372 objects as known or candidate cataclysmic variables (CVs) during the second year of the operation of the Zwicky Transient Facility. From the available difference imaging data, we found that 93 are previously confirmed CVs and 279 are strong candidates. Spectra of four of the candidates confirm them as CVs by the presence of Balmer emission lines, while one of the four has prominent He ii lines indicative of containing a magnetic white dwarf. Gaia EDR3 parallaxes are available for 154 of these systems, resulting in distances from 108–2096 pc and absolute magnitudes in the range of 7.5–15.0, with the largest number of candidates between 10.5 and 12.5. The total numbers are 21% higher than from the previous year of the survey with a greater number of distances available but a smaller percentage of systems close to the Galactic plane. Comparison of these findings with a machine-learning method of searching all the light curves reveals large differences in each data set related to the parameters involved in the search process.
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| 46. |
- Yao, Yuhan, et al.
(författare)
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ZTF Early Observations of Type Ia Supernovae. I. Properties of the 2018 Sample
- 2019
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 886:2
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Tidskriftsartikel (refereegranskat)abstract
- Early-time observations of Type Ia supernovae (SNe Ia) are essential to constrain the properties of their progenitors. In this paper, we present high-quality light curves of 127 SNe Ia discovered by the Zwicky Transient Facility (ZTF) in 2018. We describe our method to perform forced point-spread function photometry, which can be applied to other types of extragalactic transients. With a planned cadence of six observations per night (three g + three r), all of the 127 SNe Ia are detected in both g and r bands more than 10 days (in the rest frame) prior to the epoch of g-band maximum light. The redshifts of these objects range from z = 0.0181 to 0.165; the median redshift is 0.074. Among the 127 SNe, 50 are detected at least 14 days prior to maximum light (in the rest frame), with a subset of nine objects being detected more than 17 days before g-band peak. This is the largest sample of young SNe Ia collected to date; it can be used to study the shape and color evolution of the rising light curves in unprecedented detail. We discuss six peculiar events in this sample: one 02cx-like event ZTF18abclfee (SN 2018crl), one Ia-CSM SN ZTF18aaykjei (SN 2018cxk), and four objects with possible super-Chandrasekhar mass progenitors: ZTF18abhpgje (SN 2018eul), ZTF18abdpvnd (SN 2018dvf), ZTF18aawpcel (SN 2018cir), and ZTF18abddmrf (SN 2018dsx).
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| 47. |
- Kanai, M, et al.
(författare)
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- 2023
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