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- Sugai, H., et al.
(author)
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Updated Design of the CMB Polarization Experiment Satellite LiteBIRD
- 2020
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In: Journal of Low Temperature Physics. - : Springer Science and Business Media LLC. - 0022-2291 .- 1573-7357. ; 199:3-4, s. 1107-1117
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Journal article (peer-reviewed)abstract
- Recent developments of transition-edge sensors (TESs), based on extensive experience in ground-based experiments, have been making the sensor techniques mature enough for their application on future satellite cosmic microwave background (CMB) polarization experiments. LiteBIRD is in the most advanced phase among such future satellites, targeting its launch in Japanese Fiscal Year 2027 (2027FY) with JAXA's H3 rocket. It will accommodate more than 4000 TESs in focal planes of reflective low-frequency and refractive medium-and-high-frequency telescopes in order to detect a signature imprinted on the CMB by the primordial gravitational waves predicted in cosmic inflation. The total wide frequency coverage between 34 and 448 GHz enables us to extract such weak spiral polarization patterns through the precise subtraction of our Galaxy's foreground emission by using spectral differences among CMB and foreground signals. Telescopes are cooled down to 5 K for suppressing thermal noise and contain polarization modulators with transmissive half-wave plates at individual apertures for separating sky polarization signals from artificial polarization and for mitigating from instrumental 1/f noise. Passive cooling by using V-grooves supports active cooling with mechanical coolers as well as adiabatic demagnetization refrigerators. Sky observations from the second Sun-Earth Lagrangian point, L2, are planned for 3 years. An international collaboration between Japan, the USA, Canada, and Europe is sharing various roles. In May 2019, the Institute of Space and Astronautical Science, JAXA, selected LiteBIRD as the strategic large mission No. 2.
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| 7. |
- Abazajian, Kevork, et al.
(author)
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CMB-S4 : Forecasting Constraints on Primordial Gravitational Waves
- 2022
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 926:1
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Journal article (peer-reviewed)abstract
- CMB-S4—the next-generation ground-based cosmic microwave background (CMB) experiment—is set to significantly advance the sensitivity of CMB measurements and enhance our understanding of the origin and evolution of the universe. Among the science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. This work details the development of a forecasting framework that includes a power-spectrum-based semianalytic projection tool, targeted explicitly toward optimizing constraints on the tensor-to-scalar ratio, r, in the presence of Galactic foregrounds and gravitational lensing of the CMB. This framework is unique in its direct use of information from the achieved performance of current Stage 2–3 CMB experiments to robustly forecast the science reach of upcoming CMB-polarization endeavors. The methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments, given a desired scientific goal. To form a closed-loop process, we couple this semianalytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. We document multiple rounds of forecasts for CMB-S4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the Stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for r > 0.003 at greater than 5σ, or in the absence of a detection, of reaching an upper limit of r < 0.001 at 95% CL.
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- Ade, Peter, et al.
(author)
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The Simons Observatory : science goals and forecasts
- 2019
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In: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :2
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Journal article (peer-reviewed)abstract
- The Simons Observatory (SO) is a new cosmic microwave background experiment being built on Cerro Toco in Chile, due to begin observations in the early 2020s. We describe the scientific goals of the experiment, motivate the design, and forecast its performance. SO will measure the temperature and polarization anisotropy of the cosmic microwave background in six frequency bands centered at: 27, 39, 93, 145, 225 and 280 GHz. The initial con figuration of SO will have three small-aperture 0.5-m telescopes and one large-aperture 6-m telescope, with a total of 60,000 cryogenic bolometers. Our key science goals are to characterize the primordial perturbations, measure the number of relativistic species and the mass of neutrinos, test for deviations from a cosmological constant, improve our understanding of galaxy evolution, and constrain the duration of reionization. The small aperture telescopes will target the largest angular scales observable from Chile, mapping approximate to 10% of the sky to a white noise level of 2 mu K-arcmin in combined 93 and 145 GHz bands, to measure the primordial tensor-to-scalar ratio, r, at a target level of sigma(r) = 0.003. The large aperture telescope will map approximate to 40% of the sky at arcminute angular resolution to an expected white noise level of 6 mu K-arcmin in combined 93 and 145 GHz bands, overlapping with the majority of the Large Synoptic Survey Telescope sky region and partially with the Dark Energy Spectroscopic Instrument. With up to an order of magnitude lower polarization noise than maps from the Planck satellite, the high-resolution sky maps will constrain cosmological parameters derived from the damping tail, gravitational lensing of the microwave background, the primordial bispectrum, and the thermal and kinematic Sunyaev-Zel'dovich effects, and will aid in delensing the large-angle polarization signal to measure the tensor-to-scalar ratio. The survey will also provide a legacy catalog of 16,000 galaxy clusters and more than 20,000 extragalactic sources.
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| 10. |
- Jung, Christian, et al.
(author)
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A comparison of very old patients admitted to intensive care unit after acute versus elective surgery or intervention
- 2019
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In: Journal of critical care. - : W B SAUNDERS CO-ELSEVIER INC. - 0883-9441 .- 1557-8615. ; 52, s. 141-148
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Journal article (peer-reviewed)abstract
- Background: We aimed to evaluate differences in outcome between patients admitted to intensive care unit (ICU) after elective versus acute surgery in a multinational cohort of very old patients (80 years; VIP). Predictors of mortality, with special emphasis on frailty, were assessed.Methods: In total, 5063 VIPs were induded in this analysis, 922 were admitted after elective surgery or intervention, 4141 acutely, with 402 after acute surgery. Differences were calculated using Mann-Whitney-U test and Wilcoxon test. Univariate and multivariable logistic regression were used to assess associations with mortality.Results: Compared patients admitted after acute surgery, patients admitted after elective surgery suffered less often from frailty as defined as CFS (28% vs 46%; p < 0.001), evidenced lower SOFA scores (4 +/- 5 vs 7 +/- 7; p < 0.001). Presence of frailty (CFS >4) was associated with significantly increased mortality both in elective surgery patients (7% vs 12%; p = 0.01), in acute surgery (7% vs 12%; p = 0.02).Conclusions: VIPs admitted to ICU after elective surgery evidenced favorable outcome over patients after acute surgery even after correction for relevant confounders. Frailty might be used to guide clinicians in risk stratification in both patients admitted after elective and acute surgery.
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| 11. |
- Basu, K., et al.
(author)
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Non-parametric modeling of the intra-cluster gas using APEX-SZ bolometer imaging data
- 2010
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 519:Article Number: A29
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Journal article (peer-reviewed)abstract
- Aims. We aim to demonstrate the usability of mm-wavelength imaging data obtained from the APEX-SZ bolometer array to derive the radial temperature profile of the hot intra-cluster gas out to radius r(500) and beyond. The goal is to study the physical properties of the intra-cluster gas by using a non-parametric de-projection method that is, aside from the assumption of spherical symmetry, free from modeling bias. Methods. We use publicly available X-ray spectroscopic-imaging data in the 0.7-2 keV energy band from the XMM-Newton observatory and our Sunyaev-Zel'dovich Effect (SZE) imaging data from the APEX-SZ experiment at 150 GHz to de-project the density and temperature profiles for a well-studied relaxed cluster, Abell 2204. We derive the gas density, temperature and entropy profiles assuming spherical symmetry, and obtain the total mass profile under the assumption of hydrostatic equilibrium. For comparison with X-ray spectroscopic temperature models, a re-analysis of recent Chandra observation is done with the latest calibration updates. We compare the results with that from an unrelaxed cluster, Abell 2163, to illustrate some differences between relaxed and merging systems. Results. Using the non-parametric modeling, we demonstrate a decrease of gas temperature in the cluster outskirts, and also measure gas entropy profiles, both of which are done for the first time independently of X-ray spectroscopy using the SZE and X-ray imaging data. The gas entropy measurement in the central 100 kpc shows the usability of APEX-SZ data for inferring cluster dynamical states with this method. The contribution of the SZE systematic uncertainties in measuring T-e at large radii is shown to be small compared to XMM-Newton and Chandra systematic spectroscopic errors. The total mass profile obtained using the hydrostatic equilibrium assumption is in agreement with the published X-ray and weak lensing results; the upper limit on M-200 derived from the non-parametric method is consistent with the NFW model prediction from weak lensing analysis.
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| 12. |
- Bender, A. N., et al.
(author)
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Galaxy cluster scaling relations measured with APEX-SZ
- 2016
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In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 460:4, s. 3432-3446
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Journal article (peer-reviewed)abstract
- We present thermal Sunyaev-Zel'dovich effect (SZE) measurements for 42 galaxy clusters observed at 150 GHz with the APEX-SZ experiment. For each cluster, we model the pressure profile and calculate the integrated Comptonization Y to estimate the total thermal energy of the intraclustermedium (ICM). We compare the measured Y values to X-ray observables of the ICM from the literature (cluster gas mass M-gas, temperature T-X, and Y-X = MgasTX) that relate to total cluster mass. We measure power-law scaling relations, including an intrinsic scatter, between the SZE and X-ray observables for three subsamples within the set of 42 clusters that have uniform X-ray analysis in the literature. We observe that differences between these X-ray analyses introduce significant variance into the measured scaling relations, particularly affecting the normalization. For all three subsamples, we find results consistent with a selfsimilarmodel of cluster evolution dominated by gravitational effects. Comparing to predictions from numerical simulations, these scaling relations prefer models that include cooling and feedback in the ICM. Lastly, we measure an intrinsic scatter of similar to 28 per cent in the Y - Y-X scaling relation for all three subsamples.
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| 14. |
- Schwan, D., et al.
(author)
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APEX-SZ: The Atacama Pathfinder EXperiment Sunyaev-Zel'dovich Instrument
- 2012
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In: The Messenger. ; 147, s. 7-12
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Journal article (other academic/artistic)abstract
- The APEX–SZ instrument was a millimetre-wave (150 GHz) cryogenic receiverfor the APEX telescope designedto observe galaxy clusters via theSunyaev–Zel’dovich Effect (SZE). Thereceiver contained a focal plane of280 superconducting transition-edgesensor bolometers equipped with afrequency-domain-multiplexed readoutsystem, and it played a key role in theintroduction of these new, robust, andscalable technologies. With 1-arcminuteresolution, the instrument had a higherinstantaneous sensitivity and covered alarger field of view (22 arcminutes) thanearlier generations of SZE instruments.During its period of operation from 2007to 2010, APEX–SZ was used to imageover 40 clusters and map fields overlappingwith external datasets. This paperbriefly describes the instrument anddata reduction procedure and presentsa cluster image gallery, as well as resultsfor the Bullet cluster, Abell 2204, Abell2163, and a power spectrum analysis inthe XMM-LSS field.
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| 15. |
- Schwan, D., et al.
(author)
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Invited Article: Millimeter-wave bolometer array receiver for the Atacama pathfinder experiment Sunyaev-Zel'dovich (APEX-SZ) instrument
- 2011
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In: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 82:9
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Journal article (peer-reviewed)abstract
- The Atacama pathfinder experiment Sunyaev-Zel'dovich (APEX-SZ) instrument is a millimeter-wave cryogenic receiver designed to observe galaxy clusters via the Sunyaev-Zel'dovich effect from the 12 m APEX telescope on the Atacama plateau in Chile. The receiver contains a focal plane of 280 superconducting transition-edge sensor (TES) bolometers instrumented with a frequency-domain multiplexed readout system. The bolometers are cooled to 280 mK via a three-stage helium sorption refrigerator and a mechanical pulse-tube cooler. Three warm mirrors, two 4 K lenses, and a horn array couple the TES bolometers to the telescope. APEX-SZ observes in a single frequency band at 150 GHz with 1' angular resolution and a 22' field-of-view, all well suited for cluster mapping. The APEX-SZ receiver has played a key role in the introduction of several new technologies including TES bolometers, the frequency-domain multiplexed readout, and the use of a pulse-tube cooler with bolometers. As a result of these new technologies, the instrument has a higher instantaneous sensitivity and covers a larger field-of-view than earlier generations of Sunyaev-Zel'dovich instruments. The TES bolometers have a median sensitivity of 890 mu K(CMB)root s (NEy of 3.5 x 10(-4) root s). We have also demonstrated upgraded detectors with improved sensitivity of 530 mu K(CMB) root s (NEy of 2.2 x 10(-4) root s). Since its commissioning in April 2007, APEX-SZ has been used to map 48 clusters. We describe the design of the receiver and its performance when installed on the APEX telescope.
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| 16. |
- van den Bosch, R, et al.
(author)
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Striatal dopamine dissociates methylphenidate effects on value-based versus surprise-based reversal learning
- 2022
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In: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1, s. 4962-
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Journal article (peer-reviewed)abstract
- Psychostimulants such as methylphenidate are widely used for their cognitive enhancing effects, but there is large variability in the direction and extent of these effects. We tested the hypothesis that methylphenidate enhances or impairs reward/punishment-based reversal learning depending on baseline striatal dopamine levels and corticostriatal gating of reward/punishment-related representations in stimulus-specific sensory cortex. Young healthy adults (N = 100) were scanned with functional magnetic resonance imaging during a reward/punishment reversal learning task, after intake of methylphenidate or the selective D2/3-receptor antagonist sulpiride. Striatal dopamine synthesis capacity was indexed with [18F]DOPA positron emission tomography. Methylphenidate improved and sulpiride decreased overall accuracy and response speed. Both drugs boosted reward versus punishment learning signals to a greater degree in participants with higher dopamine synthesis capacity. By contrast, striatal and stimulus-specific sensory surprise signals were boosted in participants with lower dopamine synthesis. These results unravel the mechanisms by which methylphenidate gates both attention and reward learning.
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| 17. |
- Hagstrom, H., et al.
(author)
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Outcomes of Pregnancy in Mothers With Cirrhosis: A National Population-Based Cohort Study of 1.3 Million Pregnancies
- 2018
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In: Hepatology Communications. - : Ovid Technologies (Wolters Kluwer Health). - 2471-254X. ; 2:11, s. 1299-1305
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Journal article (peer-reviewed)abstract
- There are limited data on pregnancy outcomes in women with cirrhosis. To address this gap, we examined the records of singleton births from Sweden's National Patient Register (NPR), Cause of Death Register (CDR), and Medical Birth Register (MBR) between 1997 and 2011 to assess exposure and pregnancy-related and liver-related outcomes of pregnant women with cirrhosis. Exposure status was defined as having an International Classification of Diseases (ICU) code for cirrhosis obtained prior to or during pregnancy. Poisson regression with cluster-robust standard errors was used to estimate relative risks (RRs) adjusted for maternal age, smoking, and body mass index (BMI). We identified 103 pregnancies in women with cirrhosis and compared these to 1,361,566 pregnancies in women without cirrhosis. Pregnancies in women with cirrhosis were at increased risk of caesarean delivery (36% versus 16%, respectively; adjusted RR [aRR], 2.00; 95% confidence interval [CI] 1.47-2.73), low birth weight (15% versus 3%; aRR, 3.87; 95% CI, 2.11-7.06), and preterm delivery (19% versus 5%; aRR, 3.51; 95% CI, 2.16-5.72). Rates of maternal mortality during pregnancy (no cases), gestational diabetes, preeclampsia, small for gestational age, congenital malformations, and stillbirth were not increased when compared to the pregnant women without cirrhosis. There were 12 hospitalizations during pregnancy due to liver-related events, including one case with bleeding esophageal varices. Conclusion: Women with cirrhosis are at increased risk for adverse pregnancy outcomes. However, severe maternal and fetal adverse events were rare in our study, and most pregnancies in women with cirrhosis ended without complications.
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| 20. |
- McCusker, Karina, et al.
(author)
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The first microwave and submillimetre closure study using particle models of oriented ice hydrometeors to simulate polarimetric measurements of ice clouds
- 2024
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In: Atmospheric Measurement Techniques. - 1867-1381 .- 1867-8548. ; 17:11, s. 3533-3552
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Journal article (peer-reviewed)abstract
- The first closure study involving passive microwave and submillimetre measurements of ice clouds with the consideration of oriented particles is presented, using a unique combination of polarised observations from the ISMAR spectral-like radiometer, two radars with frequencies of 35 and 95GHz, and a variety of in situ instruments. Of particular interest to this study are the large V-H polarised brightness temperature differences measured from ISMAR above a thick frontal ice cloud. Previous studies combining radar and passive submillimetre measurements have not considered polarisation differences. Moreover, they have assumed particle habits a priori. We aim to test whether the large V-H measurements can be simulated successfully by using an atmospheric model consistent with in situ microphysics. An atmospheric model is constructed using information from the in situ measurements, such as the ice water content, the particle size distribution, and the mass and shape of particles, as well as background information obtained from dropsonde profiles. Columnar and dendritic aggregate particle models are generated specifically for this case, and their scattering properties are calculated using the independent monomer approximation under the assumption of horizontal orientation. The scattering properties are used to perform polarised radiative transfer simulations using ARTS to test whether we can successfully simulate the measured large V-H differences. Radar measurements are used to extrapolate the 1-D microphysical profile to derive a time series of particle size distributions which are used to simulate ISMAR brightness temperatures. These simulations are compared to the observations. It is found that particle models that are consistent with in situ microphysics observations are capable of reproducing the brightness temperature depression and polarisation signature measured from ISMAR at the dual-polarised channel of 243GHz. However, it was required that a proportion of the particles were changed in order to increase the V-H polarised brightness temperature differences. Thus, we incorporated millimetre-sized dendritic crystals, as these particles were observed in the probe imagery. At the second dual-polarised channel of 664GHz, the brightness temperature depressions were generally simulated at the correct locations; however, the simulated V-H was too large. This work shows that multi-frequency polarisation information could be used to infer realistic particle shapes, orientations, and representations of the split between single crystals and aggregates within the cloud.
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| 21. |
- Nagarajan, A., et al.
(author)
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Weak-lensing mass calibration of the Sunyaev-Zel'dovich effect using APEX-SZ galaxy clusters
- 2019
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In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 488:2, s. 1728-1759
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Journal article (peer-reviewed)abstract
- The use of galaxy clusters as precision cosmological probes relies on an accurate determination of their masses. However, inferring the relationship between cluster mass and observables from direct observations is difficult and prone to sample selection biases. In this work, we use weak lensing as the best possible proxy for cluster mass to calibrate the Sunyaev-Zel'dovich (SZ) effect measurements from the APEX-SZ experiment. For a well-defined (ROSAT) X-ray complete cluster sample, we calibrate the integrated Comptonization parameter, Y-SZ, to the weak-lensing derived total cluster mass, M-500. We employ a novel Bayesian approach to account for the selection effects by jointly fitting both the SZ Comptonization, Y-SZ-M-500, and the X-ray luminosity, Lx-M-500, scaling relations. We also account for a possible correlation between the intrinsic (lognormal) scatter of L-x and Y-SZ at fixed mass. We find the corresponding correlation coefficient to be r = 0.47(-0.35)(+0.24), and at the current precision level our constraints on the scaling relations are consistent with previous works. For our APEX-SZ sample, we find that ignoring the covariance between the SZ and X-ray observables biases the normalization of the Y-SZ-M-500 scaling high by 1-2 sigma and the slope low by similar to 1 sigma, even when the SZ effect plays no role in the sample selection. We conclude that for higher precision data and larger cluster samples, as anticipated from on-going and near-future cluster cosmology experiments, similar biases (due to intrinsic covariances of cluster observables) in the scaling relations will dominate the cosmological error budget if not accounted for correctly.
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