Photovoltaic (PV) solar energy generating capacity has grown by 41 per cent per year since 2009
. Energy system projections that mitigate climate change and aid universal energy access show a nearly ...ten-fold increase in PV solar energy generating capacity by 2040
. Geospatial data describing the energy system are required to manage generation intermittency, mitigate climate change risks, and identify trade-offs with biodiversity, conservation and land protection priorities caused by the land-use and land-cover change necessary for PV deployment. Currently available inventories of solar generating capacity cannot fully address these needs
. Here we provide a global inventory of commercial-, industrial- and utility-scale PV installations (that is, PV generating stations in excess of 10 kilowatts nameplate capacity) by using a longitudinal corpus of remote sensing imagery, machine learning and a large cloud computation infrastructure. We locate and verify 68,661 facilities, an increase of 432 per cent (in number of facilities) on previously available asset-level data. With the help of a hand-labelled test set, we estimate global installed generating capacity to be 423 gigawatts (-75/+77 gigawatts) at the end of 2018. Enrichment of our dataset with estimates of facility installation date, historic land-cover classification and proximity to vulnerable areas allows us to show that most of the PV solar energy facilities are sited on cropland, followed by aridlands and grassland. Our inventory could aid PV delivery aligned with the Sustainable Development Goals.
Secular trends in dialysis therapy delivery require a frequent re-examination of outcomes in patients on renal replacement modalities. We examined four large cohorts of patients initiating peritoneal ...dialysis (PD) in 2000–2003 (total of >40000 patients) to ascertain trends in patient outcomes, technique success, and predictors of both parameters of interest. Age, end-stage renal disease vintage, and diabetes were clear predictors of patient survival. Technique success was higher in patients on automated PD than in patients on continuous ambulatory PD. Center size was a powerful predictor of technique success. We conclude that the current state of PD in the United States is characterized by improving patient outcomes, higher technique success, and a predominance of use of cycler-based therapy. Several opportunities for improving technique success amenable to practice interventions have been identified.
We present a measurement of the angular power spectrum of the cosmic microwave background (CMB) using data from the South Pole Telescope (SPT). The data consist of 790 deg2 of sky observed at 150 GHz ...during 2008 and 2009. Here we present the power spectrum over the multipole range 650 < l < 3000, where it is dominated by primary CMB anisotropy. We combine this power spectrum with the power spectra from the seven-year Wilkinson Microwave Anisotropy Probe (WMAP) data release to constrain cosmological models. We find that the SPT and WMAP data are consistent with each other and, when combined, are well fit by a spatially flat, Delta *LCDM cosmological model. The SPT+WMAP constraint on the spectral index of scalar fluctuations is ns = 0.9663 ? 0.0112. We detect, at ~5 Delta *s significance, the effect of gravitational lensing on the CMB power spectrum, and find its amplitude to be consistent with the Delta *LCDM cosmological model. We explore a number of extensions beyond the Delta *LCDM model. Each extension is tested independently, although there are degeneracies between some of the extension parameters. We constrain the tensor-to-scalar ratio to be r < 0.21 (95% CL) and constrain the running of the scalar spectral index to be dns /dln k = --0.024 ? 0.013. We strongly detect the effects of primordial helium and neutrinos on the CMB; a model without helium is rejected at 7.7 Delta *s, while a model without neutrinos is rejected at 7.5 Delta *s. The primordial helium abundance is measured to be Yp = 0.296 ? 0.030, and the effective number of relativistic species is measured to be N eff = 3.85 ? 0.62. The constraints on these models are strengthened when the CMB data are combined with measurements of the Hubble constant and the baryon acoustic oscillation feature. Notable improvements include ns = 0.9668 ? 0.0093, r < 0.17 (95% CL), and N eff = 3.86 ? 0.42. The SPT+WMAP data show a mild preference for low power in the CMB damping tail, and while this preference may be accommodated by models that have a negative spectral running, a high primordial helium abundance, or a high effective number of relativistic species, such models are disfavored by the abundance of low-redshift galaxy clusters.
We present the first three-frequency South Pole Telescope (SPT) cosmic microwave background (CMB) power spectra. The band powers presented here cover angular scales 2000 < l < 9400 in frequency bands ...centered at 95, 150, and 220 GHz. At these frequencies and angular scales, a combination of the primary CMB anisotropy, thermal and kinetic Sunyaev-Zel'dovich (SZ) effects, radio galaxies, and cosmic infrared background (CIB) contributes to the signal. We combine Planck/HFI and SPT data at 220 GHz to constrain the amplitude and shape of the CIB power spectrum and find strong evidence for nonlinear clustering. We explore the SZ results using a variety of cosmological models for the CMB and CIB anisotropies and find them to be robust with one exception: allowing for spatial correlations between the thermal SZ effect and CIB significantly degrades the SZ constraints. Neglecting this potential correlation, we find the thermal SZ power at 150 GHz and l = 3000 to be 3.65 + or - 0.69 mu K super(2), and set an upper limit on the kinetic SZ power to be less than 2.8 mu K super(2) at 95% confidence. When a correlation between the thermal SZ and CIB is allowed, we constrain a linear combination of thermal and kinetic SZ power: D super(tSZ) sub(3000) + 0.5D sub(3000) super(kSZ) = 4.60 + or - 0.63 mu K super(2), consistent with earlier measurements. We use the measured thermal SZ power and an analytic, thermal SZ model calibrated with simulations to determine sigma sub(8) = 0.807 + or - 0.016. Modeling uncertainties involving the astrophysics of the intracluster medium rather than the statistical uncertainty in the measured band powers are the dominant source of uncertainty on sigma sub(8). We also place an upper limit on the kinetic SZ power produced by patchy reionization; a companion paper uses these limits to constrain the reionization history of the universe.
In the past decade, our understanding of galaxy evolution has been revolutionized by the discovery that luminous, dusty starburst galaxies were 1,000 times more abundant in the early Universe than at ...present. It has, however, been difficult to measure the complete redshift distribution of these objects, especially at the highest redshifts (z > 4). Here we report a redshift survey at a wavelength of three millimetres, targeting carbon monoxide line emission from the star-forming molecular gas in the direction of extraordinarily bright millimetre-wave-selected sources. High-resolution imaging demonstrates that these sources are strongly gravitationally lensed by foreground galaxies. We detect spectral lines in 23 out of 26 sources and multiple lines in 12 of those 23 sources, from which we obtain robust, unambiguous redshifts. At least 10 of the sources are found to lie at z > 4, indicating that the fraction of dusty starburst galaxies at high redshifts is greater than previously thought. Models of lens geometries in the sample indicate that the background objects are ultra-luminous infrared galaxies, powered by extreme bursts of star formation.
We detect the kinematic Sunyaev-Zel'dovich (kSZ) effect with a statistical significance of 4.2σ by combining a cluster catalogue derived from the first year data of the Dark Energy Survey with cosmic ...microwave background temperature maps from the South Pole Telescope Sunyaev-Zel'dovich Survey. This measurement is performed with a differential statistic that isolates the pairwise kSZ signal, providing the first detection of the large-scale, pairwise motion of clusters using redshifts derived from photometric data. By fitting the pairwise kSZ signal to a theoretical template, we measure the average central optical depth of the cluster sample,
$\bar{\tau }_e = (3.75 \pm 0.89)\times 10^{-3}$
. We compare the extracted signal to realistic simulations and find good agreement with respect to the signal to noise, the constraint on
$\bar{\tau }_e$
, and the corresponding gas fraction. High-precision measurements of the pairwise kSZ signal with future data will be able to place constraints on the baryonic physics of galaxy clusters, and could be used to probe gravity on scales ≳100 Mpc.
We present first results on the cooling properties derived from Chandra X-ray observations of 83 high-redshift (0.3 < z < 1.2) massive galaxy clusters selected by their Sunyaev-Zel'dovich signature ...in the South Pole Telescope data. We measure each cluster's central cooling time, central entropy, and mass deposition rate, and compare these properties to those for local cluster samples. We find no significant evolution from z ~ 0 to z ~ 1 in the distribution of these properties, suggesting that cooling in cluster cores is stable over long periods of time. We also find that the average cool core entropy profile in the inner ~100 kpc has not changed dramatically since z ~ 1, implying that feedback must be providing nearly constant energy injection to maintain the observed "entropy floor" at ~10 keV cm super(2). While the cooling properties appear roughly constant over long periods of time, we observe strong evolution in the gas density profile, with the normalized central density (rhog, 0/rho sub(crit)) increasing by an order of magnitude from z ~ 1 to z ~ 0. When using metrics defined by the inner surface brightness profile of clusters, we find an apparent lack of classical, cuspy, cool-core clusters at z > 0.75, consistent with earlier reports for clusters at z > 0.5 using similar definitions. Our measurements indicate that cool cores have been steadily growing over the 8 Gyr spanned by our sample, consistent with a constant, ~150 M sub(middot in circle) yr super(-1) cooling flow that is unable to cool below entropies of 10 keV cm super(2) and, instead, accumulates in the cluster center. We estimate that cool cores began to assemble in these massive systems at z sub(cool) = 1.0 super(+1.0) sub(-0.2), which represents the first constraints on the onset of cooling in galaxy cluster cores. At high redshift (z > ~ 0.75), galaxy clusters may be classified as "cooling flows" (low central entropy, cooling time) but not "cool cores" (cuspy surface brightness profile), meaning that care must be taken when classifying these high-z systems. We investigate several potential biases that could conspire to mimic this cool core evolution and are unable to find a bias that has a similar redshift dependence and a substantial amplitude.
The epoch of re-ionization is a milestone of cosmological structure formation, marking the birth of the first objects massive enough to yield large numbers of ionizing photons. Measurements of the ...cosmic microwave background (CMB) Doppler effect from ionizing bubbles embedded in large-scale velocity streams - known as the patchy kinetic Sunyaev-Zel'dovich (kSZ) effect - can be used to constrain the duration of re-ionization. Using new multi-frequency data from the South Pole Telescope (SPT), we show that the ionized fraction evolved relatively rapidly. We combine the SPT constraint on the duration of re-ionization with the Wilkinson Microwave Anisotropy Probe measurement of the integrated optical depth to probe the cosmic ionization history. We find that re-ionization ended with 95% confidence at z > 7.2 under the assumption of no tSZ-CIB correlation, and z > 5.8 when correlations are allowed. These CMB observations complement other observational probes of the epoch of re-ionization such as the red-shifted 21 cm line and narrow-band surveys for Lyalpha-emitting galaxies.
We present three maps of the millimeter-wave sky created by combining data from the South Pole Telescope (SPT) and the Planck satellite. We use data from the SPT-SZ survey, a survey of 2540 deg2 of ...the the sky with arcminute resolution in three bands centered at 95, 150, and 220 GHz, and the full-mission Planck temperature data in the 100, 143, and 217 GHz bands. A linear combination of the SPT-SZ and Planck data is computed in spherical harmonic space, with weights derived from the noise of both instruments. This weighting scheme results in Planck data providing most of the large-angular-scale information in the combined maps, with the smaller-scale information coming from SPT-SZ data. A number of tests have been done on the maps. We find their angular power spectra to agree very well with theoretically predicted spectra and previously published results.
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