Publications
1042 results found
Guarnieri P, Maraston C, Thomas D, et al., 2019, Candidate massive galaxies at <i>z</i> ∼ 4 in the Dark Energy Survey, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 483, Pages: 3060-3081, ISSN: 0035-8711
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- Citations: 15
Dafsari HS, Martinez-Martin P, Rizos A, et al., 2019, EuroInf 2: Subthalamic stimulation, apomorphine, and levodopa infusion in Parkinson's disease, MOVEMENT DISORDERS, Vol: 34, Pages: 353-365, ISSN: 0885-3185
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- Citations: 98
Yanny B, Stringer KM, Long JP, et al., 2019, Identification of RR Lyrae Stars in Multiband, Sparsely Sampled Data from the Dark Energy Survey Using Template Fitting and Random Forest Classification, Astronomical Journal, Vol: 158, ISSN: 0004-6256
Many studies have shown that RR Lyrae variable stars (RRL) are powerful stellar tracers of Galactic halo structure and satellite galaxies. The Dark Energy Survey (DES), with its deep and wide coverage (g ∼23.5 mag in a single exposure; over 5000 deg2) provides a rich opportunity to search for substructures out to the edge of the Milky Way halo. However, the sparse and unevenly sampled multiband light curves from the DES wide-field survey (a median of four observations in each of grizY over the first three years) pose a challenge for traditional techniques used to detect RRL. We present an empirically motivated and computationally efficient template-fitting method to identify these variable stars using three years of DES data. When tested on DES light curves of previously classified objects in SDSS stripe 82, our algorithm recovers 89% of RRL periods to within 1% of their true value with 85% purity and 76% completeness. Using this method, we identify 5783 RRL candidates, ∼28% of which are previously undiscovered. This method will be useful for identifying RRL in other sparse multiband data sets.
Abbott TMC, Allam S, Andersen P, et al., 2019, First Cosmology Results using Type Ia Supernovae from the Dark Energy Survey: Constraints on Cosmological Parameters, Astrophysical Journal Letters, Vol: 872, ISSN: 2041-8205
We present the first cosmological parameter constraints using measurements of type Ia supernovae (SNe Ia) from the Dark Energy Survey Supernova Program (DES-SN). The analysis uses a subsample of 207 spectroscopically confirmed SNe Ia from the first three years of DES-SN, combined with a low-redshift sample of 122 SNe from the literature. Our "DES-SN3YR" result from these 329 SNe Ia is based on a series of companion analyses and improvements covering SN Ia discovery, spectroscopic selection, photometry, calibration, distance bias corrections, and evaluation of systematic uncertainties. For a flat ΛCDM model we find a matter density Ω m = 0.331 ± 0.038. For a flat wCDM model, and combining our SN Ia constraints with those from the cosmic microwave background (CMB), we find a dark energy equation of state w = -0.978 ± 0.059, and ω m = 0.321 ± 0.018. For a flat w 0 w a CDM model, and combining probes from SN Ia, CMB and baryon acoustic oscillations, we find w0 = -0.885 ± 0.114 and w a = -0.387 ± 0.430. These results are in agreement with a cosmological constant and with previous constraints using SNe Ia (Pantheon, JLA).
Doctor Z, Kessler R, Herner K, et al., 2019, A Search for Optical Emission from Binary Black Hole Merger GW170814 with the Dark Energy Camera, Astrophysical Journal Letters, Vol: 873, ISSN: 2041-8205
Binary black hole (BBH) mergers found by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo detectors are of immense scientific interest to the astrophysics community, but are considered unlikely to be sources of electromagnetic emission. To test whether they have rapidly fading optical counterparts, we used the Dark Energy Camera to perform an i-band search for the BBH merger GW170814, the first gravitational wave (GW) detected by three interferometers. The 87 deg 2 localization region (at 90% confidence) centered in the Dark Energy Survey (DES) footprint enabled us to image 86% of the probable sky area to a depth of i ∼ 23 mag and provide the most comprehensive data set to search for electromagnetic (EM) emission from BBH mergers. To identify candidates, we perform difference imaging with our search images and with templates from pre-existing Dark Energy Survey (DES) images. The analysis strategy and selection requirements were designed to remove supernovae and to identify transients that decline in the first two epochs. We find two candidates, each of which is spatially coincident with a star or a high-redshift galaxy in the DES catalogs, and they are thus unlikely to be associated with GW170814. Our search finds no candidates associated with GW170814, disfavoring rapidly declining optical emission from BBH mergers brighter than i ∼ 23 mag (L optical ∼ 5 ×10 41 erg s -1 ) 1-2 days after coalescence. In terms of GW sky map coverage, this is the most complete search for optical counterparts to BBH mergers to date.
Banda-Huarca MV, Camargo JIB, Desmars J, et al., 2019, Astrometry and Occultation Predictions to Trans-Neptunian and Centaur Objects Observed within the Dark Energy Survey, Astronomical Journal, Vol: 157, ISSN: 0004-6256
Trans-Neptunian objects (TNOs) are a source of invaluable information to access the history and evolution of the outer solar system. However, observing these faint objects is a difficult task. As a consequence, important properties such as size and albedo are known for only a small fraction of them. Now, with the results from deep sky surveys and the Gaia space mission, a new exciting era is within reach as accurate predictions of stellar occultations by numerous distant small solar system bodies become available. From them, diameters with kilometer accuracies can be determined. Albedos, in turn, can be obtained from diameters and absolute magnitudes. We use observations from the Dark Energy Survey (DES) from 2012 November until 2016 February, amounting to 4,292,847 charge-coupled device (CCD) frames. We searched them for all known small solar system bodies and recovered a total of 202 TNOs and Centaurs, 63 of which have been discovered by the DES collaboration as of the date of submission. Their positions were determined using the Gaia Data Release 2 as reference and their orbits were refined. Stellar occultations were then predicted using these refined orbits plus stellar positions from Gaia. These predictions are maintained, and updated, in a dedicated web service. The techniques developed here are also part of an ambitious preparation to use the data from the Large Synoptic Survey Telescope (LSST), that expects to obtain accurate positions and multifilter photometry for tens of thousands of TNOs.
McGinnity CJ, Arstad E, Beck K, et al., 2019, Comment on "<i>In Vivo</i> [<SUP>18</SUP>F]GE-179 Brain Signal Does Not Show NMDA-Specific Modulation with Drug Challenges in Rodents and Nonhuman Primates", ACS CHEMICAL NEUROSCIENCE, Vol: 10, Pages: 768-772, ISSN: 1948-7193
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- Citations: 8
Ishikawa Y, Sirk MM, Edelstein J, et al., 2018, Comprehensive Measurements of the Volume-phase Holographic Gratings for the Dark Energy Spectroscopic Instrument, Astrophysical Journal, Vol: 869, ISSN: 0004-637X
The Dark Energy Spectroscopic Instrument (DESI) is a Stage IV ground-based dark energy experiment that will be employed on the Mayall 4 m Telescope to study the expansion history of the universe. In the era of massively multiplexed fiber-fed spectrographs, DESI will push the boundaries of fiber spectroscopy with a design capable of taking 5000 simultaneous spectra over 360 to 980 nm. The instrument utilizes a suite of three-channel spectrographs, where volume-phase holographic (VPH) gratings provide dispersions. Thirty-six VPH gratings were produced and their performances were evaluated at the Lawrence Berkeley National Laboratory. We present the design and the evaluation tests for the production run of the VPH gratings, verifying the incidence angle, area-weighted efficiency, and wavefront errors (WFEs). We also present the specialized test set-up developed on-site to assess the grating performances. Measurements of the VPH gratings show high consistency in area-weighted efficiency to within an rms of 2% for the red and near-infrared and 6.2% for the blue gratings. Measured WFEs also showed high consistency per bandpass. Comprehensive evaluations show that the VPH gratings meet DESI performance requirements and have been approved for integration.
Abbott TMC, Abdalla FB, Allam S, et al., 2018, The Dark Energy Survey: Data Release 1, ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, Vol: 239, ISSN: 0067-0049
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- Citations: 356
Lillethorup TP, Glud AN, Landeck N, et al., 2018, In vivo quantification of glial activation in minipigs overexpressing human α-synuclein, SYNAPSE, Vol: 72, ISSN: 0887-4476
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- Citations: 12
Li TS, Simon JD, Kuehn K, et al., 2018, The First Tidally Disrupted Ultra-faint Dwarf Galaxy?: A Spectroscopic Analysis of the Tucana III Stream, Astrophysical Journal, Vol: 866, ISSN: 0004-637X
We present a spectroscopic study of the tidal tails and core of the Milky Way satellite Tucana III, collectively referred to as the Tucan III stream, using the 2dF+AAOmega spectrograph on the Anglo-Australian Telescope and the IMACS spectrograph on the Magellan Baade Telescope. In addition to recovering the brightest nine previously known member stars in the Tucana III core, we identify 22 members in the tidal tails.We observe strong evidence for a velocity gradient of 8.0 ± 0.4 km s-1 deg-1 over at least 3° on the sky. Based on the continuity in velocity, we confirm that the Tucana III tails are real tidal extensions of Tucana III. The large velocity gradient of the stream implies that Tucana III is likely on a radial orbit. We successfully obtain metallicities for four members in the core and 12 members in the tails. We find that members close to the ends of the stream tend to be more metal-poor than members in the core, indicating a possible metallicity gradient between the center of the progenitor halo and its edge. The spread in metallicity suggests that the progenitor of the Tucana III stream is likely a dwarf galaxy rather than a star cluster. Furthermore, we find that with the precise photometry of the Dark Energy Survey data, there is a discernible color offset between metal-rich disk stars and metal-poor stream members. This metallicity-dependent color offers a more efficient method to recognize metal-poor targets and will increase the selection efficiency of stream members for future spectroscopic follow-up programs on stellar streams.
Knudsen K, Fedorova T, Hansen A, et al., 2018, In vivo staging of pathology in REM sleep behaviour disorder, International Congress of Parkinson's Disease and Movement Disorders, Publisher: WILEY, Pages: S708-S708, ISSN: 0885-3185
Sridharan S, Raffel J, Nandoskar A, et al., 2018, Confirmation of specific binding of the 18 kDa translocator protein (TSPO) radioligand [<SUP>18</SUP>F]GE-180: a blocking study using XDB173 in multiple sclerosis, 34th Congress of the European-Committee-for-Treatment-and-Research-in-Multiple-Sclerosis (ECTRIMS), Publisher: SAGE PUBLICATIONS LTD, Pages: 421-422, ISSN: 1352-4585
Edison P, Dani M, wood M, et al., 2018, Microglial activation correlates in vivo with both tau and amyloid in Alzheimer’s disease, Brain, Vol: 141, Pages: 2740-2754, ISSN: 1460-2156
Alzheimer’s disease is characterized by the histopathological presence of amyloid-β plaques and tau-containing neurofibrillary tangles. Microglial activation is also a recognized pathological component. The relationship between microglial activation and protein aggregation is still debated. We investigated the relationship between amyloid plaques, tau tangles and activated microglia using PET imaging. Fifty-one subjects (19 healthy controls, 16 mild cognitive impairment and 16 Alzheimer’s disease subjects) participated in the study. All subjects had neuropsychometric testing, MRI, amyloid (18F-flutemetamol), and microglial (11C-PBR28) PET. All subjects with mild cognitive impairment and Alzheimer’s disease and eight of the controls had tau (18F-AV1451) PET. 11C-PBR28 PET was analysed using Logan graphical analysis with an arterial plasma input function, while 18F-flutemetamol and 18F-AV1451 PET were analysed as target:cerebellar ratios to create parametric standardized uptake value ratio maps. Biological parametric mapping in the Statistical Parametric Mapping platform was used to examine correlations between uptake of tracers at a voxel-level. There were significant widespread clusters of positive correlation between levels of microglial activation and tau aggregation in both the mild cognitive impairment (amyloid-positive and amyloid-negative) and Alzheimer’s disease subjects. The correlations were stronger in Alzheimer’s disease than in mild cognitive impairment, suggesting that these pathologies increase together as disease progresses. Levels of microglial activation and amyloid deposition were also correlated, although in a different spatial distribution; correlations were stronger in mild cognitive impairment than Alzheimer’s subjects, in line with a plateauing of amyloid load with disease progression. Clusters of positive correlations between microglial activation and protein aggregation often targeted similar areas of
Parbo P, Ismail R, Sommerauer M, et al., 2018, Does inflammation precede tau aggregation in early Alzheimer's disease? A PET study, NEUROBIOLOGY OF DISEASE, Vol: 117, Pages: 211-216, ISSN: 0969-9961
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- Citations: 38
Shipp N, Drlica-Wagner A, Balbinot E, et al., 2018, Stellar Streams Discovered in the Dark Energy Survey, Astrophysical Journal, Vol: 862, ISSN: 0004-637X
We perform a search for stellar streams around the Milky Way using the first 3 yr of multiband optical imaging data from the Dark Energy Survey (DES). We use DES data covering ∼5000 deg2 to a depth of g > 23.5 with a relative photometric calibration uncertainty of <1%. This data set yields unprecedented sensitivity to the stellar density field in the southern celestial hemisphere, enabling the detection of faint stellar streams to a heliocentric distance of ∼50 kpc. We search for stellar streams using a matched filter in color-magnitude space derived from a synthetic isochrone of an old, metal-poor stellar population. Our detection technique recovers four previously known thin stellar streams: Phoenix, ATLAS, Tucana III, and a possible extension of Molonglo. In addition, we report the discovery of 11 new stellar streams. In general, the new streams detected by DES are fainter, more distant, and lower surface brightness than streams detected by similar techniques in previous photometric surveys. As a by-product of our stellar stream search, we find evidence for extratidal stellar structure associated with four globular clusters: NGC 288, NGC 1261, NGC 1851, and NGC 1904. The ever-growing sample of stellar streams will provide insight into the formation of the Galactic stellar halo, the Milky Way gravitational potential, and the large- and small-scale distribution of dark matter around the Milky Way.
Becker JC, Khain T, Hamilton SJ, et al., 2018, Discovery and Dynamical Analysis of an Extreme Trans-Neptunian Object with a High Orbital Inclination, Astronomical Journal, Vol: 156, ISSN: 0004-6256
We report the discovery and dynamical analysis of 2015 BP519, an extreme trans-Neptunian object (TNO) detected by the Dark Energy Survey at a heliocentric distance of 55 au, perihelion of ∼36 au, and absolute magnitude H r = 4.3. The current orbit, determined from a 1110 day observational arc, has a semimajor axis a ≈ 450 au, eccentricity e ≈ 0.92, and inclination i ≈ 547deg;. With these orbital elements, 2015 BP519 is the most extreme TNO discovered to date, as quantified by the reduced Kozai action, , which is a conserved quantity at fixed semimajor axis a for axisymmetric perturbations. We discuss the orbital stability and evolution of this object and find that, under the influence of the four known giant planets, 2015 BP519 displays rich dynamical behavior, including rapid diffusion in semimajor axis and more constrained variations in eccentricity and inclination. We also consider the long-term orbital stability and evolutionary behavior within the context of the Planet Nine hypothesis and find that 2015 BP519 adds to the circumstantial evidence for the existence of this proposed new member of the solar system, as it would represent the first member of the population of high-i, π-shepherded TNOs.
Femminella G, Fan Z, Frangou E, et al., 2018, Peripheral insulin resistance does not correlate with cerebral glucose metabolic rate in non-diabetic Alzheimer’s patients, Alzheimer's and Dementia, Vol: 14, Pages: P1157-P1158, ISSN: 1552-5260
Calsolaro V, Fan Z, Veronese M, et al., 2018, Novel third generation microglial marker flutriciclamide ([18F]GE180) in Alzheimer’s disease and mild cognitive impairment, Alzheimer's and Dementia, Vol: 14, Pages: P506-P506, ISSN: 1552-5260
Fan Z, Dani M, Femminella GD, et al., 2018, Parametric mapping using spectral analysis for11C-PBR28 PET reveals neuroinflammation in mild cognitive impairment subjects, European Journal of Nuclear Medicine and Molecular Imaging, Vol: 45, Pages: 1432-1441, ISSN: 1619-7070
PURPOSE: Neuroinflammation and microglial activation play an important role in amnestic mild cognitive impairment (MCI) and Alzheimer's disease. In this study, we investigated the spatial distribution of neuroinflammation in MCI subjects, using spectral analysis (SA) to generate parametric maps and quantify11C-PBR28 PET, and compared these with compartmental and other kinetic models of quantification. METHODS: Thirteen MCI and nine healthy controls were enrolled in this study. Subjects underwent11C-PBR28 PET scans with arterial cannulation. Spectral analysis with an arterial plasma input function was used to generate11C-PBR28 parametric maps. These maps were then compared with regional11C-PBR28 VT(volume of distribution) using a two-tissue compartment model and Logan graphic analysis. Amyloid load was also assessed with18F-Flutemetamol PET. RESULTS: With SA, three component peaks were identified in addition to blood volume. The11C-PBR28 impulse response function (IRF) at 90 min produced the lowest coefficient of variation. Single-subject analysis using this IRF demonstrated microglial activation in five out of seven amyloid-positive MCI subjects. IRF parametric maps of11C-PBR28 uptake revealed a group-wise significant increase in neuroinflammation in amyloid-positive MCI subjects versus HC in multiple cortical association areas, and particularly in the temporal lobe. Interestingly, compartmental analysis detected group-wise increase in11C-PBR28 binding in the thalamus of amyloid-positive MCI subjects, while Logan parametric maps did not perform well. CONCLUSIONS: This study demonstrates for the first time that spectral analysis can be used to generate parametric maps of11C-PBR28 uptake, and is able to detect microglial activation in amyloid-positive MCI subjects. IRF parametric maps of11C-PBR28 uptake allow voxel-wise single-subject analysis and could be used to evaluate microglial activation in individual subjects.
Knudsen K, Fedorova TD, Hansen AK, et al., 2018, In-vivo staging of pathology in REM sleep behaviour disorder: a multimodality imaging case-control study, LANCET NEUROLOGY, Vol: 17, Pages: 618-628, ISSN: 1474-4422
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- Citations: 184
Minett T, Su L, Mak E, et al., 2018, Longitudinal diffusion tensor imaging changes in early Parkinson's disease: ICICLE-PD study, JOURNAL OF NEUROLOGY, Vol: 265, Pages: 1528-1539, ISSN: 0340-5354
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- Citations: 29
Mattsson N, Groot C, Jansen WJ, et al., 2018, Prevalence of the apolipoprotein E ε4 allele in amyloid β positive subjects across the spectrum of Alzheimer's disease, ALZHEIMERS & DEMENTIA, Vol: 14, Pages: 913-924, ISSN: 1552-5260
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- Citations: 51
Stokholm MG, Iranzo A, Ostergaard K, et al., 2018, Extrastriatal monoaminergic dysfunction and enhanced microglial activation in idiopathic rapid eye movement sleep behaviour disorder, NEUROBIOLOGY OF DISEASE, Vol: 115, Pages: 9-16, ISSN: 0969-9961
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- Citations: 25
Edison P, Brooks D, 2018, Role of neuroinflammation in Alzheimer’s trajectory and in vivo quantification using PET, Journal of Alzheimers Disease, Vol: 64, Pages: S339-S351, ISSN: 1387-2877
Recent evidence suggests that neuroinflammation and immunity play a significant role in Alzheimer’s disease and other neurodegenerative diseases. It has also been observed that, independent of the presence of aggregated proteins, neuroinflammation could be present in different neurodegenerative diseases. It has also been suggested that neuroinflammation could occur well ahead of amyloid deposition in AD. Recent genetic studies and other preclinical studies specifically point to a role of neuroinflammation and, in this review, we evaluate the evidence of neuroinflammation in the Alzheimer’s disease trajectory and the different imaging modalities by which we could monitor neuroinflammation in vivo in humans.
McGinnity CJ, Riaño Barros DA, Trigg W, et al., 2018, Simplifying [18F]GE-179 PET: are both arterial blood sampling and 90-min acquisitions essential?, EJNMMI Research, Vol: 8, ISSN: 2191-219X
INTRODUCTION: The NMDA receptor radiotracer [18F]GE-179 has been used with 90-min scans and arterial plasma input functions. We explored whether (1) arterial blood sampling is avoidable and (2) shorter scans are feasible. METHODS: For 20 existing [18F]GE-179 datasets, we generated (1) standardised uptake values (SUVs) over eight intervals; (2) volume of distribution (VT) images using population-based input functions (PBIFs), scaled using one parent plasma sample; and (3) VT images using three shortened datasets, using the original parent plasma input functions (ppIFs). RESULTS: Correlations with the original ppIF-derived 90-min VTs increased for later interval SUVs (maximal ρ = 0.78; 80-90 min). They were strong for PBIF-derived VTs (ρ = 0.90), but between-subject coefficient of variation increased. Correlations were very strong for the 60/70/80-min original ppIF-derived VTs (ρ = 0.97-1.00), which suffered regionally variant negative bias. CONCLUSIONS: Where arterial blood sampling is available, reduction of scan duration to 60 min is feasible, but with negative bias. The performance of SUVs was more consistent across participants than PBIF-derived VTs.
Sommerauer M, Hansen AK, Parbo P, et al., 2018, Decreased noradrenaline transporter density in the motor cortex of Parkinson's disease patients, Movement Disorders, Vol: 33, Pages: 1006-1010, ISSN: 0885-3185
Reduced noradrenaline levels have been reported to occur in the motor cortices of PD patients postmortem. Imaging techniques have recently become available to specifically study noradrenergic terminal function in vivo using PET. The objective of this study was to evaluate cortical 11 C-MeNER binding in PD patients. Thirty PD patients and 12 healthy control subjects comparable in age, sex, and cognitive performance underwent PET imaging with 11 C-MeNER, a specific ligand of the noradrenaline transporter. Cortical noradrenaline transporter binding was compared at a voxel level using Statistical Parametric Mapping, whereas cortical thickness was assessed using FreeSurfer software with MRI. PD patients showed reduced 11 C-MeNER binding in the primary motor cortex unrelated to cortical thickness; other cortical regions did not differ between groups. In a subgroup analysis, patients with higher Hoehn & Yahr stage exhibited more pronounced 11 C-MeNER binding reductions. Loss of cortical noradrenergic projections to the primary motor cortex occurs in PD associated with disease stage. © 2018 International Parkinson and Movement Disorder Society.
Chaudhuri KR, Poewe W, Brooks D, 2018, Motor and Nonmotor Complications of Levodopa: Phenomenology, Risk Factors, and Imaging Features, MOVEMENT DISORDERS, Vol: 33, Pages: 909-919, ISSN: 0885-3185
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- Citations: 71
Hansen AK, Brooks DJ, Borghammer P, 2018, MAO-B Inhibitors Do Not Block <i>In Vivo</i> Flortaucipir([<SUP>18</SUP>F]-AV-1451) Binding, MOLECULAR IMAGING AND BIOLOGY, Vol: 20, Pages: 356-360, ISSN: 1536-1632
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- Citations: 38
Prasad S, Pal PK, 2018, Levodopa-Induced Dyskinesia: "TRAP"ping the Culprit., Mov Disord, Vol: 33
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