1. |
- Bravo, L, et al.
(author)
-
- 2021
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swepub:Mat__t
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2. |
- Tabiri, S, et al.
(author)
-
- 2021
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swepub:Mat__t
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3. |
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4. |
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5. |
- Achterberg, A., et al.
(author)
-
Detection of atmospheric muon neutrinos with the IceCube 9-string detector
- 2007
-
In: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998. ; 76:2, s. 027101-
-
Journal article (peer-reviewed)abstract
- The IceCube neutrino detector is a cubic kilometer TeV to PeV neutrino detector under construction at the geographic South Pole. The dominant population of neutrinos detected in IceCube is due to meson decay in cosmic-ray air showers. These atmospheric neutrinos are relatively well understood and serve as a calibration and verification tool for the new detector. In 2006, the detector was approximately 10% completed, and we report on data acquired from the detector in this configuration. We observe an atmospheric neutrino signal consistent with expectations, demonstrating that the IceCube detector is capable of identifying neutrino events. In the first 137.4 days of live time, 234 neutrino candidates were selected with an expectation of 211 +/- 76.1(syst)+/- 14.5(stat) events from atmospheric neutrinos.
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6. |
- Achterberg, A., et al.
(author)
-
Multiyear search for a diffuse flux of muon neutrinos with AMANDA-II
- 2007
-
In: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998. ; 76:4, s. 042008-
-
Journal article (peer-reviewed)abstract
- A search for TeV-PeV muon neutrinos from unresolved sources was performed on AMANDA-II data collected between 2000 and 2003 with an equivalent live time of 807 days. This diffuse analysis sought to find an extraterrestrial neutrino flux from sources with nonthermal components. The signal is expected to have a harder spectrum than the atmospheric muon and neutrino backgrounds. Since no excess of events was seen in the data over the expected background, an upper limit of E-2 Phi(90%C.L.)< 7.4x10(-8) GeV cm(-2) s(-1) sr(-1) is placed on the diffuse flux of muon neutrinos with a Phi proportional to E-2 spectrum in the energy range 16 TeV to 2.5 PeV. This is currently the most sensitive Phi proportional to E-2 diffuse astrophysical neutrino limit. We also set upper limits for astrophysical and prompt neutrino models, all of which have spectra different from Phi proportional to E-2.
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7. |
- Achterberg, A., et al.
(author)
-
The search for muon neutrinos from northern hemisphere gamma-ray bursts with AMANDA
- 2008
-
In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 674:1, s. 357-370
-
Journal article (peer-reviewed)abstract
- We present the results of the analysis of neutrino observations by the Antarctic Muon and Neutrino Detector Array (AMANDA) correlated with photon observations of more than 400 gamma-ray bursts (GRBs) in the northern hemisphere from 1997 to 2003. During this time period, AMANDA's effective collection area for muon neutrinos was larger than that of any other existing detector. After the application of various selection criteria to our data, we expect similar to 1 neutrino event and <2 background events. Based on our observations of zero events during and immediately prior to the GRBs in the data set, we set the most stringent upper limit on muon neutrino emission correlated with GRBs. Assuming a Waxman-Bahcall spectrum and incorporating all systematic uncertainties, our flux upper limit has a normalization at 1 PeV of E-2 Phi(nu) <= 6.3 x 10(-9) GeV cm(-2) s(-1) sr(-1), with 90% of the events expected within the energy range of similar to 10 TeV to similar to 3 PeV. The impact of this limit on several theoretical models of GRBs is discussed, as well as the future potential for detection of GRBs by next-generation neutrino telescopes. Finally, we briefly describe several modifications to this analysis in order to apply it to other types of transient point sources.
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8. |
- Ackermann, M., et al.
(author)
-
Search for ultra-high-energy neutrinos with amanda-II
- 2008
-
In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 675:2, s. 1014-1024
-
Journal article (peer-reviewed)abstract
- A search for diffuse neutrinos with energies in excess of 10(5) GeV is conducted with AMANDA-II data recorded between 2000 and 2002. Above 10(7) GeV, the Earth is essentially opaque to neutrinos. This fact, combined with the limited overburden of the AMANDA-II detector ( roughly 1.5 km), concentrates these ultra-high-energy neutrinos at the horizon. The primary background for this analysis is bundles of downgoing, high-energy muons from the interaction of cosmic rays in the atmosphere. No statistically significant excess above the expected background is seen in the data, and an upper limit is set on the diffuse all-flavor neutrino flux of E-2 Phi(90%CL) < 2.7x10(-7) GeV cm(-2) s(-1) sr(-1) valid over the energy range of 2x10(5) to 10(9) GeV. A number of models that predict neutrino fluxes from active galactic nuclei are excluded at the 90% confidence level.
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9. |
- Abbasi, R., et al.
(author)
-
Search for point sources of high energy neutrinos with final data from AMANDA-II
- 2009
-
In: Physical Review D. - 1550-7998 .- 1550-2368. ; 79, s. 062001-
-
Journal article (peer-reviewed)abstract
- We present a search for point sources of high energy neutrinos using 3.8 yr of data recorded by AMANDA-II during 2000-2006. After reconstructing muon tracks and applying selection criteria designed to optimally retain neutrino-induced events originating in the northern sky, we arrive at a sample of 6595 candidate events, predominantly from atmospheric neutrinos with primary energy 100 GeV to 8 TeV. Our search of this sample reveals no indications of a neutrino point source. We place the most stringent limits to date on E(-2) neutrino fluxes from points in the northern sky, with an average upper limit of E(2)Phi(nu mu)+nu(tau)<= 5.2x10(-11) TeV cm(-2) s(-1) on the sum of nu(mu) and nu(tau) fluxes, assumed equal, over the energy range from 1.9 TeV to 2.5 PeV.
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10. |
- Abbasi, R., et al.
(author)
-
The IceCube data acquisition system : Signal capture, digitization, and timestamping
- 2009
-
In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 601:3, s. 294-316
-
Journal article (peer-reviewed)abstract
- IceCube is a km-scale neutrino observatory under construction at the South Pole with sensors both in the deep ice (InIce) and on the surface (IceTop). The sensors, called Digital Optical Modules (DOMs). detect, digitize and timestamp the signals from optical Cherenkov-radiation photons. The DOM Main Board (MB) data acquisition subsystem is connected to the central DAQ in the IceCube Laboratory (ICL) by a single twisted copper wire-pair and transmits packetized data on demand. Time calibration is maintained throughout the array by regular transmission to the DOMs of precisely timed analog signals, synchronized to a central GPS-disciplined clock. The design goals and consequent features, functional capabilities, and initial performance of the DOM MB, and the operation of a combined array of DOMs as a system, are described here. Experience with the first InIce strings and the IceTop stations indicates that the system design and performance goals have been achieved. (c) 2009 Elsevier B.V. All rights reserved.
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11. |
- Poyatos, R., et al.
(author)
-
Global transpiration data from sap flow measurements: the SAPFLUXNET database
- 2021
-
In: Earth System Science Data. - : Copernicus GmbH. - 1866-3508 .- 1866-3516. ; 13:6, s. 2607-2649
-
Journal article (peer-reviewed)abstract
- Plant transpiration links physiological responses of vegetation to water supply and demand with hydrological, energy, and carbon budgets at the land-atmosphere interface. However, despite being the main land evaporative flux at the global scale, transpiration and its response to environmental drivers are currently not well constrained by observations. Here we introduce the first global compilation of whole-plant transpiration data from sap flow measurements (SAPFLUXNET, https://sapfluxnet.creaf.cat/, last access: 8 June 2021). We harmonized and quality-controlled individual datasets supplied by contributors worldwide in a semi-automatic data workflow implemented in the R programming language. Datasets include sub-daily time series of sap flow and hydrometeorological drivers for one or more growing seasons, as well as metadata on the stand characteristics, plant attributes, and technical details of the measurements. SAPFLUXNET contains 202 globally distributed datasets with sap flow time series for 2714 plants, mostly trees, of 174 species. SAPFLUXNET has a broad bioclimatic coverage, with woodland/shrubland and temperate forest biomes especially well represented (80 % of the datasets). The measurements cover a wide variety of stand structural characteristics and plant sizes. The datasets encompass the period between 1995 and 2018, with 50 % of the datasets being at least 3 years long. Accompanying radiation and vapour pressure deficit data are available for most of the datasets, while on-site soil water content is available for 56 % of the datasets. Many datasets contain data for species that make up 90 % or more of the total stand basal area, allowing the estimation of stand transpiration in diverse ecological settings. SAPFLUXNET adds to existing plant trait datasets, ecosystem flux networks, and remote sensing products to help increase our understanding of plant water use, plant responses to drought, and ecohydrological processes. SAPFLUXNET version 0.1.5 is freely available from the Zenodo repository (https://doi.org/10.5281/zenodo.3971689; Poyatos et al., 2020a). The "sapfluxnetr" R package - designed to access, visualize, and process SAPFLUXNET data - is available from CRAN.
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12. |
- Abbasi, R., et al.
(author)
-
Calibration and characterization of the IceCube photomultiplier tube
- 2010
-
In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 618:1-3, s. 139-152
-
Journal article (peer-reviewed)abstract
- Over 5000 PMTs are being deployed at the South Pole to compose the IceCube neutrino observatory. Many are placed deep in the ice to detect Cherenkov light emitted by the products of high-energy neutrino interactions, and others are frozen into tanks on the surface to detect particles from atmospheric cosmic ray showers. IceCube is using the 10-in. diameter R7081-02 made by Hamamatsu Photonics. This paper describes the laboratory characterization and calibration of these PMTs before deployment. PMTs were illuminated with pulses ranging from single photons to saturation level. Parameterizations are given for the single photoelectron charge spectrum and the saturation behavior. Time resolution, late pulses and afterpulses are characterized. Because the PMTs are relatively large, the cathode sensitivity uniformity was measured. The absolute photon detection efficiency was calibrated using Rayleigh-scattered photons from a nitrogen laser. Measured characteristics are discussed in the context of their relevance to IceCube event reconstruction and simulation efforts. (C) 2010 Elsevier B.V. All rights reserved.
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13. |
- Abbasi, R., et al.
(author)
-
Constraints on high-energy neutrino emission from SN 2008D
- 2011
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 527:4, s. A28-
-
Journal article (peer-reviewed)abstract
- SN 2008D, a core collapse supernova at a distance of 27 Mpc, was serendipitously discovered by the Swift satellite through an associated X-ray flash. Core collapse supernovae have been observed in association with long gamma-ray bursts and X-ray flashes and a physical connection is widely assumed. This connection could imply that some core collapse supernovae possess mildly relativistic jets in which high-energy neutrinos are produced through proton-proton collisions. The predicted neutrino spectra would be detectable by Cherenkov neutrino detectors like IceCube. A search for a neutrino signal in temporal and spatial correlation with the observed X-ray flash of SN 2008D was conducted using data taken in 2007-2008 with 22 strings of the IceCube detector. Events were selected based on a boosted decision tree classifier trained with simulated signal and experimental background data. The classifier was optimized to the position and a "soft jet" neutrino spectrum assumed for SN 2008D. Using three search windows placed around the X-ray peak, emission time scales from 100-10 000 s were probed. No events passing the cuts were observed in agreement with the signal expectation of 0.13 events. Upper limits on the muon neutrino flux from core collapse supernovae were derived for different emission time scales and the principal model parameters were constrained. While no meaningful limits can be given in the case of an isotropic neutrino emission, the parameter space for a jetted emission can be constrained. Future analyses with the full 86 string IceCube detector could detect up to similar to 100 events for a core-collapse supernova at 10 Mpc according to the soft jet model.
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14. |
- Abbasi, R., et al.
(author)
-
First search for atmospheric and extraterrestrial neutrino-induced cascades with the IceCube detector
- 2011
-
In: Physical Review D. - 1550-7998 .- 1550-2368. ; 84:7, s. 072001-
-
Journal article (peer-reviewed)abstract
- We report on the first search for atmospheric and for diffuse astrophysical neutrino-induced showers (cascades) in the IceCube detector using 257 days of data collected in the year 2007-2008 with 22 strings active. A total of 14 events with energies above 16 TeV remained after event selections in the diffuse analysis, with an expected total background contribution of 8.3 +/- 3.6. At 90% confidence we set an upper limit of E(2)Phi(90%CL) < 3.6 x 10(-7) GeV.cm(-2).s(-1).sr(-1) on the diffuse flux of neutrinos of all flavors in the energy range between 24 TeV and 6.6 PeV assuming that Phi proportional to E(-2) and the flavor composition of the nu(e):nu(mu):nu(tau) flux is 1:1:1 at the Earth. The atmospheric neutrino analysis was optimized for lower energies. A total of 12 events were observed with energies above 5 TeV. The observed number of events is consistent with the expected background, within the uncertainties.
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15. |
- Abbasi, R., et al.
(author)
-
First search for extremely high energy cosmogenic neutrinos with the IceCube Neutrino Observatory
- 2010
-
In: Physical review. D, Particles, fields, gravitation, and cosmology. - 1550-7998. ; 82:7, s. 072003-
-
Journal article (peer-reviewed)abstract
- We report on the results of the search for extremely-high energy neutrinos with energies above 10(7) GeV obtained with the partially (similar to 30%) constructed IceCube in 2007. From the absence of signal events in the sample of 242.1 days of effective live time, we derive a 90% C.L. model independent differential upper limit based on the number of signal events per energy decade at E-2 phi(ve+v mu+v tau) similar or equal to 1.4 x 10(-6) GeV cm(-2) sec(-1) sr(-1) for neutrinos in the energy range from 3 x 10(7) to 3 x 10(9) GeV.
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16. |
- Abbasi, R., et al.
(author)
-
Limits on a muon flux from Kaluza-Klein dark matter annihilations in the Sun from the IceCube 22-string detector
- 2010
-
In: Physical Review D. - 1550-7998 .- 1550-2368. ; 81:5, s. 057101-
-
Journal article (peer-reviewed)abstract
- A search for muon neutrinos from Kaluza-Klein dark matter annihilations in the Sun has been performed with the 22-string configuration of the IceCube neutrino detector using data collected in 104.3 days of live time in 2007. No excess over the expected atmospheric background has been observed. Upper limits have been obtained on the annihilation rate of captured lightest Kaluza-Klein particle (LKP) WIMPs in the Sun and converted to limits on the LKP-proton cross sections for LKP masses in the range 250-3000 GeV. These results are the most stringent limits to date on LKP annihilation in the Sun.
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17. |
- Abbasi, R., et al.
(author)
-
Limits on Neutrino Emission from Gamma-Ray Bursts with the 40 String IceCube Detector
- 2011
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 106:14, s. 141101-
-
Journal article (peer-reviewed)abstract
- IceCube has become the first neutrino telescope with a sensitivity below the TeV neutrino flux predicted from gamma-ray bursts if gamma-ray bursts are responsible for the observed cosmic-ray flux above 10(18) eV. Two separate analyses using the half-complete IceCube detector, one a dedicated search for neutrinos from p gamma interactions in the prompt phase of the gamma-ray burst fireball and the other a generic search for any neutrino emission from these sources over a wide range of energies and emission times, produced no evidence for neutrino emission, excluding prevailing models at 90% confidence.
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18. |
- Abbasi, R., et al.
(author)
-
Measurement of acoustic attenuation in South Pole ice
- 2011
-
In: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 34:6, s. 382-393
-
Journal article (peer-reviewed)abstract
- Using the South Pole Acoustic Test Setup (SPATS) and a retrievable transmitter deployed in holes drilled for the IceCube experiment, we have measured the attenuation of acoustic signals by South Pole ice at depths between 190 m and 500 m. Three data sets, using different acoustic sources, have been analyzed and give consistent results. The method with the smallest systematic uncertainties yields an amplitude attenuation coefficient alpha = 3.20 +/- 0.57 km(-1) between 10 and 30 kHz, considerably larger than previous theoretical estimates. Expressed as an attenuation length, the analyses give a consistent result for lambda equivalent to 1/alpha of similar to 300 m with 20% uncertainty. No significant depth or frequency dependence has been found.
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19. |
- Abbasi, R., et al.
(author)
-
Measurement of the anisotropy of cosmic-ray arrival directions with icecube
- 2010
-
In: The Astrophysical Journal Letters. - 2041-8205. ; 718, s. L194-L198
-
Journal article (peer-reviewed)abstract
- We report the first observation of an anisotropy in the arrival direction of cosmic rays with energies in the multi-TeV region in the Southern sky using data from the IceCube detector. Between 2007 June and 2008 March, the partially deployed IceCube detector was operated in a configuration with 1320 digital optical sensors distributed over 22 strings at depths between 1450 and 2450 m inside the Antarctic ice. IceCube is a neutrino detector, but the data are dominated by a large background of cosmic-ray muons. Therefore, the background data are suitable for high-statistics studies of cosmic rays in the southern sky. The data include 4.3 billion muons produced by downward-going cosmic-ray interactions in the atmosphere; these events were reconstructed with a median angular resolution of 3 degrees and a median energy of similar to 20 TeV. Their arrival direction distribution exhibits an anisotropy in right ascension with a first-harmonic amplitude of (6.4 +/- 0.2 stat. +/- 0.8 syst.) x 10(-4).
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20. |
- Abbasi, R., et al.
(author)
-
Measurement of the atmospheric neutrino energy spectrum from 100 GeV to 400 TeV with IceCube
- 2011
-
In: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998 .- 1550-2368. ; 83:1, s. 012001-
-
Journal article (peer-reviewed)abstract
- A measurement of the atmospheric muon neutrino energy spectrum from 100 GeV to 400 TeV was performed using a data sample of about 18 000 up-going atmospheric muon neutrino events in IceCube. Boosted decision trees were used for event selection to reject misreconstructed atmospheric muons and obtain a sample of up-going muon neutrino events. Background contamination in the final event sample is less than 1%. This is the first measurement of atmospheric neutrinos up to 400 TeV, and is fundamental to understanding the impact of this neutrino background on astrophysical neutrino observations with IceCube. The measured spectrum is consistent with predictions for the atmospheric nu(mu) + (nu) over bar (mu) flux.
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21. |
- Abbasi, R., et al.
(author)
-
Search for a Lorentz-violating sidereal signal with atmospheric neutrinos in IceCube
- 2010
-
In: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998. ; 82, s. 112003-
-
Journal article (peer-reviewed)abstract
- A search for sidereal modulation in the flux of atmospheric muon neutrinos in IceCube was performed. Such a signal could be an indication of Lorentz-violating physics. Neutrino oscillation models, derivable from extensions to the standard model, allow for neutrino oscillations that depend on the neutrino's direction of propagation. No such direction-dependent variation was found. A discrete Fourier transform method was used to constrain the Lorentz and CPT-violating coefficients in one of these models. Because of the unique high energy reach of IceCube, it was possible to improve constraints on certain Lorentz-violating oscillations by 3 orders of magnitude with respect to limits set by other experiments.
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22. |
- Abbasi, R., et al.
(author)
-
Search for dark matter from the Galactic halo with the IceCube Neutrino Telescope
- 2011
-
In: Physical Review D. - 1550-7998 .- 1550-2368. ; 84:2, s. 022004-
-
Journal article (peer-reviewed)abstract
- Self-annihilating or decaying dark matter in the Galactic halo might produce high energy neutrinos detectable with neutrino telescopes. We have conducted a search for such a signal using 276 days of data from the IceCube 22-string configuration detector acquired during 2007 and 2008. The effect of halo model choice in the extracted limit is reduced by performing a search that considers the outer halo region and not the Galactic Center. We constrain any large-scale neutrino anisotropy and are able to set a limit on the dark matter self-annihilation cross section of h similar or equal to 10(-22) cm(3) s(-1) for weakly interacting massive particle masses above 1 TeV, assuming a monochromatic neutrino line spectrum.
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23. |
- Abbasi, R., et al.
(author)
-
Search for neutrino-induced cascades with five years of AMANDA data
- 2011
-
In: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 34:6, s. 420-430
-
Journal article (peer-reviewed)abstract
- We report on the search for electromagnetic and hadronic showers ("cascades") produced by a diffuse flux of extraterrestrial neutrinos in the AMANDA neutrino telescope. Data for this analysis were recorded during 1001 days of detector livetime in the years 2000-2004. The observed event rates are consistent with the background expectation from atmospheric neutrinos and muons. An upper limit is derived for the diffuse flux of neutrinos of all flavors assuming a flavor ratio of v(e):v(mu):v(tau) = 1:1:1 at the detection site. The all-flavor flux of neutrinos with an energy spectrum Phi proportional to E-2 is less than 5.0 x 10(-7) GeV s(-1) sr(-1) cm(-2) at a 90% C.L. Here, 90% of the simulated signal would fall within the energy range 40 TeV to 9 PeV. We discuss flux limits in the context of several specific models of extraterrestrial and prompt atmospheric neutrino production.
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24. |
- Abbasi, R., et al.
(author)
-
Search for relativistic magnetic monopoles with the AMANDA-II neutrino telescope
- 2010
-
In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 69:3-4, s. 361-378
-
Journal article (peer-reviewed)abstract
- We present the search for Cherenkov signatures from relativistic magnetic monopoles in data taken with the AMANDA-II detector, a neutrino telescope deployed in the Antarctic ice cap at the Geographic South Pole. The non-observation of a monopole signal in data collected during the year 2000 improves present experimental limits on the flux of relativistic magnetic monopoles: Our flux limit varies between 3.8x10(-17) cm(-2) s(-1) sr(-1) (for monopoles moving at the vacuum speed of light) and 8.8x10(-16) cm(-2) s(-1) sr(-1) (for monopoles moving at a speed beta=v/c=0.76, just above the Cherenkov threshold in ice). These limits apply to monopoles that are energetic enough to penetrate the Earth and enter the detector from below the horizon. The limit obtained for monopoles reaching the detector from above the horizon is less stringent by roughly an order of magnitude, due to the much larger background from down-going atmospheric muons. This looser limit is however valid for a larger class of magnetic monopoles, since the monopoles are not required to pass through the Earth.
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25. |
- Abbasi, R., et al.
(author)
-
Solar energetic particle spectrum on 2006 December 13 determined by IceTop
- 2008
-
In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 689:1, s. L65-L68
-
Journal article (peer-reviewed)abstract
- On 2006 December 13 the IceTop air shower array at the South Pole detected a major solar particle event. By numerically simulating the response of the IceTop tanks, which are thick Cerenkov detectors with multiple thresholds deployed at high altitude with no geomagnetic cutoff, we determined the particle energy spectrum in the energy range 0.6-7.6 GeV. This is the first such spectral measurement using a single instrument with a well-defined viewing direction. We compare the IceTop spectrum and its time evolution with previously published results and outline plans for improved resolution of future solar particle spectra.
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26. |
- Abbasi, R., et al.
(author)
-
The energy spectrum of atmospheric neutrinos between 2 and 200 TeV with the AMANDA-II detector
- 2010
-
In: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 34:1, s. 48-58
-
Journal article (peer-reviewed)abstract
- The muon and anti-muon neutrino energy spectrum is determined from 2000-2003 AMANDA telescope data using regularised unfolding. This is the first measurement of atmospheric neutrinos in the energy range 2-200 TeV. The result is compared to different atmospheric neutrino models and it is compatible with the atmospheric neutrinos from pion and kaon decays. No significant contribution from charm had-ron decays or extraterrestrial neutrinos is detected. The capabilities to improve the measurement of the neutrino spectrum with the successor experiment IceCube are discussed.
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27. |
- Abbasi, R., et al.
(author)
-
Time-integrated Searches for Point-like Sources of Neutrinos with the 40-string IceCube Detector
- 2011
-
In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 732:1, s. 18-
-
Journal article (peer-reviewed)abstract
- We present the results of time-integrated searches for astrophysical neutrino sources in both the northern and southern skies. Data were collected using the partially completed IceCube detector in the 40-string configuration recorded between 2008 April 5 and 2009 May 20, totaling 375.5 days livetime. An unbinned maximum likelihood ratio method is used to search for astrophysical signals. The data sample contains 36,900 events: 14,121 from the northern sky, mostly muons induced by atmospheric neutrinos, and 22,779 from the southern sky, mostly high-energy atmospheric muons. The analysis includes searches for individual point sources and stacked searches for sources in a common class, sometimes including a spatial extent. While this analysis is sensitive to TeV-PeV energy neutrinos in the northern sky, it is primarily sensitive to neutrinos with energy greater than about 1 PeV in the southern sky. No evidence for a signal is found in any of the searches. Limits are set for neutrino fluxes from astrophysical sources over the entire sky and compared to predictions. The sensitivity is at least a factor of two better than previous searches (depending on declination), with 90% confidence level muon neutrino flux upper limits being between E(2)d Phi/dE similar to 2-200 x 10(-12) TeV cm(-2) s(-1) in the northern sky and between 3-700 x 10(-12) TeV cm(-2) s(-1) in the southern sky. The stacked source searches provide the best limits to specific source classes. The full IceCube detector is expected to improve the sensitivity to d Phi/dE proportional to E-2 sources by another factor of two in the first year of operation.
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28. |
- Abbasi, R, et al.
(author)
-
Extending the Search for Neutrino Point Sources with IceCube above the Horizon
- 2009
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 103:22, s. 221102-
-
Journal article (peer-reviewed)abstract
- Point source searches with the IceCube neutrino telescope have been restricted to one hemisphere, due to the exclusive selection of upward going events as a way of rejecting the atmospheric muon background. We show that the region above the horizon can be included by suppressing the background through energy-sensitive cuts. This improves the sensitivity above PeV energies, previously not accessible for declinations of more than a few degrees below the horizon due to the absorption of neutrinos in Earth. We present results based on data collected with 22 strings of IceCube, extending its field of view and energy reach for point source searches. No significant excess above the atmospheric background is observed in a sky scan and in tests of source candidates. Upper limits are reported, which for the first time cover point sources in the southern sky up to EeV energies.
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29. |
- Abbasi, R., et al.
(author)
-
Measurement of sound speed vs. depth in South Pole ice for neutrino astronomy
- 2010
-
In: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 33:5-6, s. 277-286
-
Journal article (peer-reviewed)abstract
- We have measured the speed of both pressure waves and shear waves as a function of depth between 80 and 500 m depth in South Pole ice with better than 1% precision. The measurements were made using the South Pole Acoustic Test Setup (SPATS), an array of transmitters and sensors deployed in the ice at the South Pole in order to measure the acoustic properties relevant to acoustic detection of astrophysical neutrinos. The transmitters and sensors use piezoceramics operating at similar to 5-25 kHz. Between 200 m and 500 m depth, the measured profile is consistent with zero variation of the sound speed with depth, resulting in zero refraction, for both pressure and shear waves. We also performed a complementary study featuring an explosive signal propagating vertically from 50 to 2250 m depth, from which we determined a value for the pressure wave speed consistent with that determined for shallower depths, higher frequencies, and horizontal propagation with the SPATS sensors. The sound speed profile presented here can be used to achieve good acoustic source position and emission time reconstruction in general, and neutrino direction and energy reconstruction in particular. The reconstructed quantities could also help separate neutrino signals from background. (C) 2010 Elsevier B.V. All rights reserved.
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30. |
- Abbasi, R., et al.
(author)
-
SEARCH FOR HIGH-ENERGY MUON NEUTRINOS FROM THE "NAKED-EYE" GRB 080319B WITH THE IceCube NEUTRINO TELESCOPE
- 2009
-
In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 701:2, s. 1721-1731
-
Journal article (peer-reviewed)abstract
- We report on a search with the IceCube detector for high-energy muon neutrinos from GRB 080319B, one of the brightest gamma-ray bursts (GRBs) ever observed. The fireball model predicts that a mean of 0.1 events should be detected by IceCube for a bulk Lorentz boost of the jet of 300. In both the direct on-time window of 66 s and an extended window of about 300 s around the GRB, no excess was found above background. The 90% CL upper limit on the number of track-like events from the GRB is 2.7, corresponding to a muon neutrino fluence limit of 9.5 x 10(-3) erg cm(-2) in the energy range between 120 TeV and 2.2 PeV, which contains 90% of the expected events.
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31. |
- Abbasi, R., et al.
(author)
-
Search for muon neutrinos from gamma-ray bursts with the IceCube neutrino telescope
- 2010
-
In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 710:1, s. 346-359
-
Journal article (peer-reviewed)abstract
- We present the results of searches for high-energy muon neutrinos from 41 gamma-ray bursts (GRBs) in the northern sky with the IceCube detector in its 22 string configuration active in 2007/2008. The searches cover both the prompt and a possible precursor emission as well as a model-independent, wide time window of -1 hr to + 3 hr around each GRB. In contrast to previous searches with a large GRB population, we do not utilize a standard Waxman-Bahcall GRB flux for the prompt emission but calculate individual neutrino spectra for all 41 GRBs from the burst parameters measured by satellites. For all of the three time windows, the best estimate for the number of signal events is zero. Therefore, we place 90% CL upper limits on the fluence from the prompt phase of 3.7 x 10(-3) erg cm(-2) (72 TeV-6.5 PeV) and on the fluence from the precursor phase of 2.3 x 10(-3) erg cm(-2) (2.2-55 TeV), where the quoted energy ranges contain 90% of the expected signal events in the detector. The 90% CL upper limit for the wide time window is 2.7 x 10(-3) erg cm(-2) (3 TeV-2.8 PeV) assuming an E-2 flux.
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32. |
- Serge, M. A., et al.
(author)
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Testing the Effect of Relative Pollen Productivity on the REVEALS Model : A Validated Reconstruction of Europe-Wide Holocene Vegetation
- 2023
-
In: Land. - : MDPI. - 2073-445X. ; 12:5
-
Journal article (peer-reviewed)abstract
- Reliable quantitative vegetation reconstructions for Europe during the Holocene are crucial to improving our understanding of landscape dynamics, making it possible to assess the past effects of environmental variables and land-use change on ecosystems and biodiversity, and mitigating their effects in the future. We present here the most spatially extensive and temporally continuous pollen-based reconstructions of plant cover in Europe (at a spatial resolution of 1 degrees x 1 degrees) over the Holocene (last 11.7 ka BP) using the 'Regional Estimates of VEgetation Abundance from Large Sites' (REVEALS) model. This study has three main aims. First, to present the most accurate and reliable generation of REVEALS reconstructions across Europe so far. This has been achieved by including a larger number of pollen records compared to former analyses, in particular from the Mediterranean area. Second, to discuss methodological issues in the quantification of past land cover by using alternative datasets of relative pollen productivities (RPPs), one of the key input parameters of REVEALS, to test model sensitivity. Finally, to validate our reconstructions with the global forest change dataset. The results suggest that the RPPs.st1 (31 taxa) dataset is best suited to producing regional vegetation cover estimates for Europe. These reconstructions offer a long-term perspective providing unique possibilities to explore spatial-temporal changes in past land cover and biodiversity.
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33. |
- Abbasi, R, et al.
(author)
-
Determination of the atmospheric neutrino flux and searches for new physics with AMANDA-II
- 2009
-
In: Physical Review D. - 1550-7998 .- 1550-2368. ; 79, s. 102005-
-
Journal article (peer-reviewed)abstract
- The AMANDA-II detector, operating since 2000 in the deep ice at the geographic South Pole, has accumulated a large sample of atmospheric muon neutrinos in the 100 GeV to 10 TeV energy range. The zenith angle and energy distribution of these events can be used to search for various phenomenological signatures of quantum gravity in the neutrino sector, such as violation of Lorentz invariance or quantum decoherence. Analyzing a set of 5511 candidate neutrino events collected during 1387 days of livetime from 2000 to 2006, we find no evidence for such effects and set upper limits on violation of Lorentz invariance and quantum decoherence parameters using a maximum likelihood method. Given the absence of evidence for new flavor-changing physics, we use the same methodology to determine the conventional atmospheric muon neutrino flux above 100 GeV.
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34. |
- Abbasi, R, et al.
(author)
-
FIRST NEUTRINO POINT-SOURCE RESULTS FROM THE 22 STRING ICECUBE DETECTOR
- 2009
-
In: Astrophysical Journal Letters. - 2041-8205. ; 701, s. L47-L51
-
Journal article (peer-reviewed)abstract
- We present new results of searches for neutrino point sources in the northern sky, using data recorded in 2007-2008 with 22 strings of the IceCube detector (approximately one-fourth of the planned total) and 275.7 days of live time. The final sample of 5114 neutrino candidate events agrees well with the expected background of atmospheric muon neutrinos and a small component of atmospheric muons. No evidence of a point source is found, with the most significant excess of events in the sky at 2.2 sigma after accounting for all trials. The average upper limit over the northern sky for point sources of muon-neutrinos with E-2 spectrum is E-2 Phi(v mu) < 1.4 x 10(-11) TeV cm(-2) s(-1), in the energy range from 3 TeV to 3 PeV, improving the previous best average upper limit by the AMANDA-II detector by a factor of 2.
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35. |
- Abbasi, R, et al.
(author)
-
Limits on a Muon Flux from Neutralino Annihilations in the Sun with the IceCube 22-String Detector
- 2009
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:20, s. 201302-
-
Journal article (peer-reviewed)abstract
- A search for muon neutrinos from neutralino annihilations in the Sun has been performed with the IceCube 22-string neutrino detector using data collected in 104.3 days of live time in 2007. No excess over the expected atmospheric background has been observed. Upper limits have been obtained on the annihilation rate of captured neutralinos in the Sun and converted to limits on the weakly interacting massive particle (WIMP) proton cross sections for WIMP masses in the range 250-5000 GeV. These results are the most stringent limits to date on neutralino annihilation in the Sun.
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36. |
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37. |
- Pihl, E., et al.
(author)
-
Ten new insights in climate science 2020- A horizon scan
- 2020
-
In: Global Sustainability. - : Cambridge University Press. - 2059-4798.
-
Journal article (peer-reviewed)abstract
- Non-technical summary We summarize some of the past year's most important findings within climate change-related research. New research has improved our understanding of Earth's sensitivity to carbon dioxide, finds that permafrost thaw could release more carbon emissions than expected and that the uptake of carbon in tropical ecosystems is weakening. Adverse impacts on human society include increasing water shortages and impacts on mental health. Options for solutions emerge from rethinking economic models, rights-based litigation, strengthened governance systems and a new social contract. The disruption caused by COVID-19 could be seized as an opportunity for positive change, directing economic stimulus towards sustainable investments. Technical summary A synthesis is made of ten fields within climate science where there have been significant advances since mid-2019, through an expert elicitation process with broad disciplinary scope. Findings include: (1) a better understanding of equilibrium climate sensitivity; (2) abrupt thaw as an accelerator of carbon release from permafrost; (3) changes to global and regional land carbon sinks; (4) impacts of climate change on water crises, including equity perspectives; (5) adverse effects on mental health from climate change; (6) immediate effects on climate of the COVID-19 pandemic and requirements for recovery packages to deliver on the Paris Agreement; (7) suggested long-term changes to governance and a social contract to address climate change, learning from the current pandemic, (8) updated positive cost-benefit ratio and new perspectives on the potential for green growth in the short- A nd long-term perspective; (9) urban electrification as a strategy to move towards low-carbon energy systems and (10) rights-based litigation as an increasingly important method to address climate change, with recent clarifications on the legal standing and representation of future generations. Social media summary Stronger permafrost thaw, COVID-19 effects and growing mental health impacts among highlights of latest climate science.
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38. |
- Schoch, CL, et al.
(author)
-
Nuclear ribosomal internal transcribed spacer (ITS) region as a universal DNA barcode marker for Fungi
- 2012
-
In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490. ; 109:16, s. 6241-6246
-
Journal article (peer-reviewed)abstract
- Six DNA regions were evaluated as potential DNA barcodes for Fungi, the second largest kingdom of eukaryotic life, by a multinational, multilaboratory consortium. The region of the mitochondrial cytochrome c oxidase subunit 1 used as the animal barcode was excluded as a potential marker, because it is difficult to amplify in fungi, often includes large introns, and can be insufficiently variable. Three subunits from the nuclear ribosomal RNA cistron were compared together with regions of three representative protein-coding genes (largest subunit of RNA polymerase II, second largest subunit of RNA polymerase II, and minichromosome maintenance protein). Although the protein-coding gene regions often had a higher percent of correct identification compared with ribosomal markers, low PCR amplification and sequencing success eliminated them as candidates for a universal fungal barcode. Among the regions of the ribosomal cistron, the internal transcribed spacer (ITS) region has the highest probability of successful identification for the broadest range of fungi, with the most clearly defined barcode gap between inter- and intraspecific variation. The nuclear ribosomal large subunit, a popular phylogenetic marker in certain groups, had superior species resolution in some taxonomic groups, such as the early diverging lineages and the ascomycete yeasts, but was otherwise slightly inferior to the ITS. The nuclear ribosomal small subunit has poor species-level resolution in fungi. ITS will be formally proposed for adoption as the primary fungal barcode marker to the Consortium for the Barcode of Life, with the possibility that supplementary barcodes may be developed for particular narrowly circumscribed taxonomic groups.
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39. |
- Shupe, M. D., et al.
(author)
-
Overview of the MOSAiC expedition : Atmosphere
- 2022
-
In: Elementa. - : University of California Press. - 2325-1026. ; 10:1
-
Journal article (peer-reviewed)abstract
- With the Arctic rapidly changing, the needs to observe, understand, and model the changes are essential. To support these needs, an annual cycle of observations of atmospheric properties, processes, and interactions were made while drifting with the sea ice across the central Arctic during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition from October 2019 to September 2020. An international team designed and implemented the comprehensive program to document and characterize all aspects of the Arctic atmospheric system in unprecedented detail, using a variety of approaches, and across multiple scales. These measurements were coordinated with other observational teams to explore crosscutting and coupled interactions with the Arctic Ocean, sea ice, and ecosystem through a variety of physical and biogeochemical processes. This overview outlines the breadth and complexity of the atmospheric research program, which was organized into 4 subgroups: atmospheric state, clouds and precipitation, gases and aerosols, and energy budgets. Atmospheric variability over the annual cycle revealed important influences from a persistent large-scale winter circulation pattern, leading to some storms with pressure and winds that were outside the interquartile range of past conditions suggested by long-term reanalysis. Similarly, the MOSAiC location was warmer and wetter in summer than the reanalysis climatology, in part due to its close proximity to the sea ice edge. The comprehensiveness of the observational program for characterizing and analyzing atmospheric phenomena is demonstrated via a winter case study examining air mass transitions and a summer case study examining vertical atmospheric evolution. Overall, the MOSAiC atmospheric program successfully met its objectives and was the most comprehensive atmospheric measurement program to date conducted over the Arctic sea ice. The obtained data will support a broad range of coupled-system scientific research and provide an important foundation for advancing multiscale modeling capabilities in the Arctic.
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40. |
- Wendisch, M., et al.
(author)
-
Atmospheric and Surface Processes, and Feedback Mechanisms Determining Arctic Amplification: A Review of First Results and Prospects of the (AC)(3) Project
- 2023
-
In: Bulletin of the American Meteorological Society. - : American Meteorological Society. - 0003-0007 .- 1520-0477. ; 104:1
-
Journal article (peer-reviewed)abstract
- Mechanisms behind the phenomenon of Arctic amplification are widely discussed. To contribute to this debate, the (AC)(3) project was established in 2016 (www.ac3-tr.de/). It comprises modeling and data analysis efforts as well as observational elements. The project has assembled a wealth of ground-based, airborne, shipborne, and satellite data of physical, chemical, and meteorological properties of the Arctic atmosphere, cryosphere, and upper ocean that are available for the Arctic climate research community. Short-term changes and indications of long-term trends in Arctic climate parameters have been detected using existing and new data. For example, a distinct atmospheric moistening, an increase of regional storm activities, an amplified winter warming in the Svalbard and North Pole regions, and a decrease of sea ice thickness in the Fram Strait and of snow depth on sea ice have been identified. A positive trend of tropospheric bromine monoxide (BrO) column densities during polar spring was verified. Local marine/biogenic sources for cloud condensation nuclei and ice nucleating particles were found. Atmospheric-ocean and radiative transfer models were advanced by applying new parameterizations of surface albedo, cloud droplet activation, convective plumes and related processes over leads, and turbulent transfer coefficients for stable surface layers. Four modes of the surface radiative energy budget were explored and reproduced by simulations. To advance the future synthesis of the results, cross-cutting activities are being developed aiming to answer key questions in four focus areas: lapse rate feedback, surface processes, Arctic mixed-phase clouds, and airmass transport and transformation.
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41. |
- Davis, B, et al.
(author)
-
Voices of chemical biology
- 2021
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In: Nature chemical biology. - : Springer Science and Business Media LLC. - 1552-4469 .- 1552-4450. ; 17:1, s. 1-4
-
Journal article (peer-reviewed)
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42. |
- Kehoe, Laura, et al.
(author)
-
Make EU trade with Brazil sustainable
- 2019
-
In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
-
Journal article (other academic/artistic)
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43. |
- Maes, S.L., et al.
(author)
-
Environmental drivers of increased ecosystem respiration in a warming tundra
- 2024
-
In: Nature. - : Springer Nature. - 0028-0836 .- 1476-4687. ; 629:8010, s. 105-113
-
Journal article (peer-reviewed)abstract
- Arctic and alpine tundra ecosystems are large reservoirs of organic carbon. Climate warming may stimulate ecosystem respiration and release carbon into the atmosphere. The magnitude and persistency of this stimulation and the environmental mechanisms that drive its variation remain uncertain. This hampers the accuracy of global land carbon–climate feedback projections. Here we synthesize 136 datasets from 56 open-top chamber in situ warming experiments located at 28 arctic and alpine tundra sites which have been running for less than 1 year up to 25 years. We show that a mean rise of 1.4 °C [confidence interval (CI) 0.9–2.0 °C] in air and 0.4 °C [CI 0.2–0.7 °C] in soil temperature results in an increase in growing season ecosystem respiration by 30% [CI 22–38%] (n = 136). Our findings indicate that the stimulation of ecosystem respiration was due to increases in both plant-related and microbial respiration (n = 9) and continued for at least 25 years (n = 136). The magnitude of the warming effects on respiration was driven by variation in warming-induced changes in local soil conditions, that is, changes in total nitrogen concentration and pH and by context-dependent spatial variation in these conditions, in particular total nitrogen concentration and the carbon:nitrogen ratio. Tundra sites with stronger nitrogen limitations and sites in which warming had stimulated plant and microbial nutrient turnover seemed particularly sensitive in their respiration response to warming. The results highlight the importance of local soil conditions and warming-induced changes therein for future climatic impacts on respiration.
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44. |
- Abdesselam, A., et al.
(author)
-
Boosted objects : a probe of beyond the standard model physics
- 2011
-
In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 71:6, s. 1661-
-
Journal article (peer-reviewed)abstract
- We present the report of the hadronic working group of the BOOST2010 workshop held at the University of Oxford in June 2010. The first part contains a review of the potential of hadronic decays of highly boosted particles as an aid for discovery at the LHC and a discussion of the status of tools developed to meet the challenge of reconstructing and isolating these topologies. In the second part, we present new results comparing the performance of jet grooming techniques and top tagging algorithms on a common set of benchmark channels. We also study the sensitivity of jet substructure observables to the uncertainties in Monte Carlo predictions.
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45. |
- Broekman, Maarten J. E., et al.
(author)
-
Evaluating expert-based habitat suitability information of terrestrial mammals with GPS-tracking data
- 2022
-
In: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 31:8, s. 1526-1541
-
Journal article (peer-reviewed)abstract
- Aim: Macroecological studies that require habitat suitability data for many species often derive this information from expert opinion. However, expert-based information is inherently subjective and thus prone to errors. The increasing availability of GPS tracking data offers opportunities to evaluate and supplement expert-based information with detailed empirical evidence. Here, we compared expert-based habitat suitability information from the International Union for Conservation of Nature (IUCN) with habitat suitability information derived from GPS-tracking data of 1,498 individuals from 49 mammal species.Location: Worldwide.Time period: 1998-2021.Major taxa studied: Forty-nine terrestrial mammal species.Methods: Using GPS data, we estimated two measures of habitat suitability for each individual animal: proportional habitat use (proportion of GPS locations within a habitat type), and selection ratio (habitat use relative to its availability). For each individual we then evaluated whether the GPS-based habitat suitability measures were in agreement with the IUCN data. To that end, we calculated the probability that the ranking of empirical habitat suitability measures was in agreement with IUCN's classification into suitable, marginal and unsuitable habitat types.Results: IUCN habitat suitability data were in accordance with the GPS data (> 95% probability of agreement) for 33 out of 49 species based on proportional habitat use estimates and for 25 out of 49 species based on selection ratios. In addition, 37 and 34 species had a > 50% probability of agreement based on proportional habitat use and selection ratios, respectively.Main conclusions: We show how GPS-tracking data can be used to evaluate IUCN habitat suitability data. Our findings indicate that for the majority of species included in this study, it is appropriate to use IUCN habitat suitability data in macroecological studies. Furthermore, we show that GPS-tracking data can be used to identify and prioritize species and habitat types for re-evaluation of IUCN habitat suitability data.
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46. |
- Gross, C. P., et al.
(author)
-
The biogeography of community assembly: latitude and predation drive variation in community trait distribution in a guild of epifaunal crustaceans
- 2022
-
In: Proceedings of the Royal Society B: Biological Sciences. - : The Royal Society. - 1471-2954 .- 0962-8452. ; 289:1969
-
Journal article (peer-reviewed)abstract
- While considerable evidence exists of biogeographic patterns in the intensity of species interactions, the influence of these patterns on variation in community structure is less clear. Studying how the distributions of traits in communities vary along global gradients can inform how variation in interactions and other factors contribute to the process of community assembly. Using a model selection approach on measures of trait dispersion in crustaceans associated with eelgrass (Zostera marina) spanning 30° of latitude in two oceans, we found that dispersion strongly increased with increasing predation and decreasing latitude. Ocean and epiphyte load appeared as secondary predictors; Pacific communities were more overdispersed while Atlantic communities were more clustered, and increasing epiphytes were associated with increased clustering. By examining how species interactions and environmental filters influence community structure across biogeographic regions, we demonstrate how both latitudinal variation in species interactions and historical contingency shape these responses. Community trait distributions have implications for ecosystem stability and functioning, and integrating large-scale observations of environmental filters, species interactions and traits can help us predict how communities may respond to environmental change.
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47. |
- Hugelius, Gustaf, et al.
(author)
-
Large stocks of peatland carbon and nitrogen are vulnerable to permafrost thaw
- 2020
-
In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 117:34, s. 20438-20446
-
Journal article (peer-reviewed)abstract
- Northern peatlands have accumulated large stocks of organic carbon (C) and nitrogen (N), but their spatial distribution and vulnerability to climate warming remain uncertain. Here, we used machine-learning techniques with extensive peat core data (n > 7,000) to create observation-based maps of northern peatland C and N stocks, and to assess their response to warming and permafrost thaw. We estimate that northern peatlands cover 3.7 ± 0.5 million km2 and store 415 ± 150 Pg C and 10 ± 7 Pg N. Nearly half of the peatland area and peat C stocks are permafrost affected. Using modeled global warming stabilization scenarios (from 1.5 to 6 °C warming), we project that the current sink of atmospheric C (0.10 ± 0.02 Pg C⋅y−1) in northern peatlands will shift to a C source as 0.8 to 1.9 million km2 of permafrost-affected peatlands thaw. The projected thaw would cause peatland greenhouse gas emissions equal to ∼1% of anthropogenic radiative forcing in this century. The main forcing is from methane emissions (0.7 to 3 Pg cumulative CH4-C) with smaller carbon dioxide forcing (1 to 2 Pg CO2-C) and minor nitrous oxide losses. We project that initial CO2-C losses reverse after ∼200 y, as warming strengthens peatland C-sinks. We project substantial, but highly uncertain, additional losses of peat into fluvial systems of 10 to 30 Pg C and 0.4 to 0.9 Pg N. The combined gaseous and fluvial peatland C loss estimated here adds 30 to 50% onto previous estimates of permafrost-thaw C losses, with southern permafrost regions being the most vulnerable.
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48. |
- Menkveld, Albert J., et al.
(author)
-
Nonstandard Errors
- 2024
-
In: JOURNAL OF FINANCE. - : Wiley-Blackwell. - 0022-1082 .- 1540-6261. ; 79:3, s. 2339-2390
-
Journal article (peer-reviewed)abstract
- In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence-generating process (EGP). We claim that EGP variation across researchers adds uncertainty-nonstandard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for more reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants.
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49. |
- Sacco, R. L., et al.
(author)
-
Aspirin and extended-release dipyridamole versus clopidogrel for recurrent stroke
- 2008
-
In: New England Journal of Medicine. - Boston : Massachusetts medical society. - 1533-4406 .- 0028-4793. ; 359:12, s. 1238-51
-
Journal article (peer-reviewed)abstract
- BACKGROUND: Recurrent stroke is a frequent, disabling event after ischemic stroke. This study compared the efficacy and safety of two antiplatelet regimens--aspirin plus extended-release dipyridamole (ASA-ERDP) versus clopidogrel. METHODS: In this double-blind, 2-by-2 factorial trial, we randomly assigned patients to receive 25 mg of aspirin plus 200 mg of extended-release dipyridamole twice daily or to receive 75 mg of clopidogrel daily. The primary outcome was first recurrence of stroke. The secondary outcome was a composite of stroke, myocardial infarction, or death from vascular causes. Sequential statistical testing of noninferiority (margin of 1.075), followed by superiority testing, was planned. RESULTS: A total of 20,332 patients were followed for a mean of 2.5 years. Recurrent stroke occurred in 916 patients (9.0%) receiving ASA-ERDP and in 898 patients (8.8%) receiving clopidogrel (hazard ratio, 1.01; 95% confidence interval [CI], 0.92 to 1.11). The secondary outcome occurred in 1333 patients (13.1%) in each group (hazard ratio for ASA-ERDP, 0.99; 95% CI, 0.92 to 1.07). There were more major hemorrhagic events among ASA-ERDP recipients (419 [4.1%]) than among clopidogrel recipients (365 [3.6%]) (hazard ratio, 1.15; 95% CI, 1.00 to 1.32), including intracranial hemorrhage (hazard ratio, 1.42; 95% CI, 1.11 to 1.83). The net risk of recurrent stroke or major hemorrhagic event was similar in the two groups (1194 ASA-ERDP recipients [11.7%], vs. 1156 clopidogrel recipients [11.4%]; hazard ratio, 1.03; 95% CI, 0.95 to 1.11). CONCLUSIONS: The trial did not meet the predefined criteria for noninferiority but showed similar rates of recurrent stroke with ASA-ERDP and with clopidogrel. There is no evidence that either of the two treatments was superior to the other in the prevention of recurrent stroke. (ClinicalTrials.gov number, NCT00153062.)
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50. |
- Yusuf, S., et al.
(author)
-
Telmisartan to prevent recurrent stroke and cardiovascular events
- 2008
-
In: New England Journal of Medicine. - : Massachusetts medical society. - 1533-4406 .- 0028-4793. ; 359:12, s. 1225-37
-
Journal article (peer-reviewed)abstract
- BACKGROUND: Prolonged lowering of blood pressure after a stroke reduces the risk of recurrent stroke. In addition, inhibition of the renin-angiotensin system in high-risk patients reduces the rate of subsequent cardiovascular events, including stroke. However, the effect of lowering of blood pressure with a renin-angiotensin system inhibitor soon after a stroke has not been clearly established. We evaluated the effects of therapy with an angiotensin-receptor blocker, telmisartan, initiated early after a stroke. METHODS: In a multicenter trial involving 20,332 patients who recently had an ischemic stroke, we randomly assigned 10,146 to receive telmisartan (80 mg daily) and 10,186 to receive placebo. The primary outcome was recurrent stroke. Secondary outcomes were major cardiovascular events (death from cardiovascular causes, recurrent stroke, myocardial infarction, or new or worsening heart failure) and new-onset diabetes. RESULTS: The median interval from stroke to randomization was 15 days. During a mean follow-up of 2.5 years, the mean blood pressure was 3.8/2.0 mm Hg lower in the telmisartan group than in the placebo group. A total of 880 patients (8.7%) in the telmisartan group and 934 patients (9.2%) in the placebo group had a subsequent stroke (hazard ratio in the telmisartan group, 0.95; 95% confidence interval [CI], 0.86 to 1.04; P=0.23). Major cardiovascular events occurred in 1367 patients (13.5%) in the telmisartan group and 1463 patients (14.4%) in the placebo group (hazard ratio, 0.94; 95% CI, 0.87 to 1.01; P=0.11). New-onset diabetes occurred in 1.7% of the telmisartan group and 2.1% of the placebo group (hazard ratio, 0.82; 95% CI, 0.65 to 1.04; P=0.10). CONCLUSIONS: Therapy with telmisartan initiated soon after an ischemic stroke and continued for 2.5 years did not significantly lower the rate of recurrent stroke, major cardiovascular events, or diabetes. (ClinicalTrials.gov number, NCT00153062.)
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