| 1. |
- Abelev, Betty, et al.
(författare)
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Long-range angular correlations on the near and away side in p-Pb collisions at root S-NN=5.02 TeV
- 2013
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 719:1-3, s. 29-41
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Tidskriftsartikel (refereegranskat)abstract
- Angular correlations between charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV for transverse momentum ranges within 0.5 < P-T,P-assoc < P-T,P-trig < 4 GeV/c. The correlations are measured over two units of pseudorapidity and full azimuthal angle in different intervals of event multiplicity, and expressed as associated yield per trigger particle. Two long-range ridge-like structures, one on the near side and one on the away side, are observed when the per-trigger yield obtained in low-multiplicity events is subtracted from the one in high-multiplicity events. The excess on the near-side is qualitatively similar to that recently reported by the CMS Collaboration, while the excess on the away-side is reported for the first time. The two-ridge structure projected onto azimuthal angle is quantified with the second and third Fourier coefficients as well as by near-side and away-side yields and widths. The yields on the near side and on the away side are equal within the uncertainties for all studied event multiplicity and p(T) bins, and the widths show no significant evolution with event multiplicity or p(T). These findings suggest that the near-side ridge is accompanied by an essentially identical away-side ridge. (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
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| 2. |
- Abelev, Betty, et al.
(författare)
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Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :11
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Tidskriftsartikel (refereegranskat)abstract
- The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.
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| 3. |
- Abelev, Betty, et al.
(författare)
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Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :7
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Tidskriftsartikel (refereegranskat)abstract
- We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%.
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| 4. |
- Abbasi, Rasha, et al.
(författare)
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IceCube search for neutrinos from GRB 221009A
- 2023
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Ingår i: Proceedings of 38th International Cosmic Ray Conference (ICRC 2023). - : Sissa Medialab Srl.
-
Konferensbidrag (refereegranskat)abstract
- GRB 221009A is the brightest Gamma Ray Burst (GRB) ever observed. The observed extremelyhigh flux of high and very-high-energy photons provide a unique opportunity to probe the predictedneutrino counterpart to the electromagnetic emission. We have used a variety of methods to searchfor neutrinos in coincidence with the GRB over several time windows during the precursor, promptand afterglow phases of the GRB. MeV scale neutrinos are studied using photo-multiplier ratescalers which are normally used to search for galactic core-collapse supernovae neutrinos. GeVneutrinos are searched starting with DeepCore triggers. These events don’t have directionallocalization, but instead can indicate an excess in the rate of events. 10 GeV - 1 TeV and >TeVneutrinos are searched using traditional neutrino point source methods which take into accountthe direction and time of events with DeepCore and the entire IceCube detector respectively. The>TeV results include both a fast-response analysis conducted by IceCube in real-time with timewindows of T0 − 1 to T0 + 2 hours and T0 ± 1 day around the time of GRB 221009A, as well asan offline analysis with 3 new time windows up to a time window of T0 − 1 to T0 + 14 days, thelongest time period we consider. The combination of observations by IceCube covers 9 ordersof magnitude in neutrino energy, from MeV to PeV, placing upper limits across the range forpredicted neutrino emission.
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| 5. |
- Fuerst, Johannes J., et al.
(författare)
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The Ice-Free Topography of Svalbard
- 2018
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 45:21, s. 11760-11769
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Tidskriftsartikel (refereegranskat)abstract
- We present a first version of the Svalbard ice-free topography (SVIFT1.0) using a mass conserving approach for mapping glacier ice thickness. SVIFT1.0 is informed by more than 1 million point measurements, totalling more than 8,700 km of thickness profiles. SVIFT1.0 is publicly available and represents the geometric state around the year 2010. Our estimate for the total ice volume is 6,199 km(3), equivalent to 1.5-cm sea level rise. The thickness map suggests that 13% of the glacierized area is grounded below sea level. A complementary map of error estimates comprises uncertainties in the thickness surveys as well as in other input variables. Aggregated error estimates are used to define a likely ice-volume range of 5,200-7,300 km(3). The ice front thickness of marine-terminating glaciers is a key quantity for ice loss attribution because it controls the potential ice discharge by iceberg calving into the ocean. We find a mean ice front thickness of 135 m for the archipelago (likely range 123-158 m). Plain Language Summary Svalbard is an archipelago in the Arctic, north of Norway, which is comparable in size to the New York metropolitan area. Roughly half of it is covered by glacier ice. Yet to this day, the ice volume stored in the many glaciers on Svalbard is not well known. Many attempts have been made to infer a total volume estimate, but results differ substantially. This surprises because of the long research activity in this area. A large record of more than 1 million thickness measurements exists, making Svalbard an ideal study area for the application of a state-of-the-art mapping approach for glacier ice thickness. The mapping approach computes an ice volume that will raise global sea level by more than half an inch if instantaneously melted. If spread over the metropolitan area, New York would be buried beneath a 100-m ice cover. The asset of this approach is that it provides not only a thickness map for each glacier on the archipelago but also an error map that defines the likely local thickness range. Finally, we provide the first well-informed estimate of the ice front thickness of all marine-terminating glaciers that loose icebergs to the ocean. The archipelago-wide mean ice front cliff is 135 m.
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| 6. |
- Zamora, Juan Carlos, et al.
(författare)
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Considerations and consequences of allowing DNA sequence data as types of fungal taxa
- 2018
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Ingår i: IMA Fungus. - : INT MYCOLOGICAL ASSOC. - 2210-6340 .- 2210-6359. ; 9:1, s. 167-185
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Tidskriftsartikel (refereegranskat)abstract
- Nomenclatural type definitions are one of the most important concepts in biological nomenclature. Being physical objects that can be re-studied by other researchers, types permanently link taxonomy (an artificial agreement to classify biological diversity) with nomenclature (an artificial agreement to name biological diversity). Two proposals to amend the International Code of Nomenclature for algae, fungi, and plants (ICN), allowing DNA sequences alone (of any region and extent) to serve as types of taxon names for voucherless fungi (mainly putative taxa from environmental DNA sequences), have been submitted to be voted on at the 11th International Mycological Congress (Puerto Rico, July 2018). We consider various genetic processes affecting the distribution of alleles among taxa and find that alleles may not consistently and uniquely represent the species within which they are contained. Should the proposals be accepted, the meaning of nomenclatural types would change in a fundamental way from physical objects as sources of data to the data themselves. Such changes are conducive to irreproducible science, the potential typification on artefactual data, and massive creation of names with low information content, ultimately causing nomenclatural instability and unnecessary work for future researchers that would stall future explorations of fungal diversity. We conclude that the acceptance of DNA sequences alone as types of names of taxa, under the terms used in the current proposals, is unnecessary and would not solve the problem of naming putative taxa known only from DNA sequences in a scientifically defensible way. As an alternative, we highlight the use of formulas for naming putative taxa (candidate taxa) that do not require any modification of the ICN.
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| 7. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 8. |
- Aartsen, M. G., et al.
(författare)
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Improved limits on dark matter annihilation in the Sun with the 79-string IceCube detector and implications for supersymmetry
- 2016
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :4
-
Tidskriftsartikel (refereegranskat)abstract
- We present an improved event-level likelihood formalism for including neutrino telescope data in global fits to new physics. We derive limits on spin-dependent dark matter-proton scattering by employing the new formalism in a re-analysis of data from the 79-string IceCube search for dark matter annihilation in the Sun, including explicit energy information for each event. The new analysis excludes a number of models in the weak-scale minimal supersymmetric standard model (MSSM) for the first time. This work is accompanied by the public release of the 79-string IceCube data, as well as an associated computer code for applying the new likelihood to arbitrary dark matter models.
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| 9. |
- Abbasi, R., et al.
(författare)
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Background studies for acoustic neutrino detection at the South Pole
- 2012
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 35:6, s. 312-324
-
Tidskriftsartikel (refereegranskat)abstract
- The detection of acoustic signals from ultra-high energy neutrino interactions is a promising method to measure the flux of cosmogenic neutrinos expected on Earth. The energy threshold for this process depends strongly on the absolute noise level in the target material. The South Pole Acoustic Test Setup (SPATS), deployed in the upper part of four boreholes of the IceCube Neutrino Observatory, has monitored the noise in Antarctic ice at the geographic South Pole for more than two years down to 500 m depth. The noise is very stable and Gaussian distributed. Lacking an in situ calibration up to now, laboratory measurements have been used to estimate the absolute noise level in the 10-50 kHz frequency range to be smaller than 20 mPa. Using a threshold trigger, sensors of the South Pole Acoustic Test Setup registered acoustic events in the IceCube detector volume and its vicinity. Acoustic signals from refreezing IceCube holes and from anthropogenic sources have been used to test the localization of acoustic events. An upper limit on the neutrino flux at energies E-v>10(11) GeV is derived from acoustic data taken over eight months. (C) 2011 Elsevier B.V. All rights reserved.
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| 10. |
- Abbasi, R., et al.
(författare)
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Calibration and characterization of the IceCube photomultiplier tube
- 2010
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 618:1-3, s. 139-152
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Tidskriftsartikel (refereegranskat)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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| 11. |
- Abbasi, R., et al.
(författare)
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Constraints on high-energy neutrino emission from SN 2008D
- 2011
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 527:4, s. A28-
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Tidskriftsartikel (refereegranskat)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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| 12. |
- Abbasi, R., et al.
(författare)
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Constraints on the extremely-high energy cosmic neutrino flux with the IceCube 2008-2009 data
- 2011
-
Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998 .- 1550-2368. ; 83:9, s. 092003-
-
Tidskriftsartikel (refereegranskat)abstract
- We report on a search for extremely-high energy neutrinos with energies greater than 10(6) GeV using the data taken with the IceCube detector at the South Pole. The data was collected between April 2008 and May 2009 with the half-completed IceCube array. The absence of signal candidate events in the sample of 333.5 days of live time significantly improves model-independent limits from previous searches and allows to place a limit on the diffuse flux of cosmic neutrinos with an E-2 spectrum in the energy range 2.0 x 10(6) - 6.3 x 10(9) GeV to a level of E-2 phi <= 3.6 x 10(-8) GeV cm(-2) sec(-1) sr(-1).
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| 13. |
- Abbasi, R, et al.
(författare)
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Extending the Search for Neutrino Point Sources with IceCube above the Horizon
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 103:22, s. 221102-
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Tidskriftsartikel (refereegranskat)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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| 14. |
- Abbasi, R, et al.
(författare)
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FIRST NEUTRINO POINT-SOURCE RESULTS FROM THE 22 STRING ICECUBE DETECTOR
- 2009
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Ingår i: Astrophysical Journal Letters. - 2041-8205. ; 701, s. L47-L51
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Tidskriftsartikel (refereegranskat)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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| 15. |
- Abbasi, R., et al.
(författare)
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First search for atmospheric and extraterrestrial neutrino-induced cascades with the IceCube detector
- 2011
-
Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 84:7, s. 072001-
-
Tidskriftsartikel (refereegranskat)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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| 16. |
- Abbasi, R., et al.
(författare)
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First search for extremely high energy cosmogenic neutrinos with the IceCube Neutrino Observatory
- 2010
-
Ingår i: Physical review. D, Particles, fields, gravitation, and cosmology. - 1550-7998. ; 82:7, s. 072003-
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Tidskriftsartikel (refereegranskat)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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| 17. |
- Abbasi, R., et al.
(författare)
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Limits on a muon flux from Kaluza-Klein dark matter annihilations in the Sun from the IceCube 22-string detector
- 2010
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 81:5, s. 057101-
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Tidskriftsartikel (refereegranskat)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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| 18. |
- Abbasi, R., et al.
(författare)
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Limits on Neutrino Emission from Gamma-Ray Bursts with the 40 String IceCube Detector
- 2011
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 106:14, s. 141101-
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Tidskriftsartikel (refereegranskat)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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| 19. |
- Abbasi, R., et al.
(författare)
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Measurement of acoustic attenuation in South Pole ice
- 2011
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 34:6, s. 382-393
-
Tidskriftsartikel (refereegranskat)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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| 20. |
- Abbasi, R., et al.
(författare)
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Measurement of sound speed vs. depth in South Pole ice for neutrino astronomy
- 2010
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 33:5-6, s. 277-286
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Tidskriftsartikel (refereegranskat)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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| 21. |
- Abbasi, R., et al.
(författare)
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Measurement of the anisotropy of cosmic-ray arrival directions with icecube
- 2010
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Ingår i: The Astrophysical Journal Letters. - 2041-8205. ; 718, s. L194-L198
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Tidskriftsartikel (refereegranskat)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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| 22. |
- Abbasi, R., et al.
(författare)
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Measurement of the atmospheric neutrino energy spectrum from 100 GeV to 400 TeV with IceCube
- 2011
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Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998 .- 1550-2368. ; 83:1, s. 012001-
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Tidskriftsartikel (refereegranskat)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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| 23. |
- Abbasi, R., et al.
(författare)
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Search for a Lorentz-violating sidereal signal with atmospheric neutrinos in IceCube
- 2010
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Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998. ; 82, s. 112003-
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Tidskriftsartikel (refereegranskat)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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| 24. |
- Abbasi, R., et al.
(författare)
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Search for dark matter from the Galactic halo with the IceCube Neutrino Telescope
- 2011
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 84:2, s. 022004-
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Tidskriftsartikel (refereegranskat)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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| 25. |
- Abbasi, R., et al.
(författare)
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Search for neutrino-induced cascades with five years of AMANDA data
- 2011
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 34:6, s. 420-430
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Tidskriftsartikel (refereegranskat)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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| 26. |
- Abbasi, R., et al.
(författare)
-
Search for relativistic magnetic monopoles with the AMANDA-II neutrino telescope
- 2010
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 69:3-4, s. 361-378
-
Tidskriftsartikel (refereegranskat)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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| 27. |
- Abbasi, R., et al.
(författare)
-
The energy spectrum of atmospheric neutrinos between 2 and 200 TeV with the AMANDA-II detector
- 2010
-
Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 34:1, s. 48-58
-
Tidskriftsartikel (refereegranskat)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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| 28. |
- Abbasi, R., et al.
(författare)
-
Time-dependent searches for point sources of neutrinos with the 40-string and 22-string configurations of IceCube
- 2012
-
Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 744:1, s. 1-
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents four searches for flaring sources of neutrinos using the IceCube neutrino telescope. For the first time, a search is performed over the entire parameter space of energy, direction, and time with sensitivity to neutrino flares lasting between 20 mu s and a year duration from astrophysical sources. Searches that integrate over time are less sensitive to flares because they are affected by a larger background of atmospheric neutrinos and muons that can be reduced by the use of additional timing information. Flaring sources considered here, such as active galactic nuclei, soft gamma-ray repeaters, and gamma-ray bursts, are promising candidate neutrino emitters. Two searches are "untriggered" in the sense that they look for any possible flare in the entire sky and from a predefined catalog of sources from which photon flares have been recorded. The other two searches are triggered by multi-wavelength information on flares from blazars and from a soft gamma-ray repeater. One triggered search uses lightcurves from Fermi-LAT which provides continuous monitoring. A second triggered search uses information where the flux states have been measured only for short periods of time near the flares. The untriggered searches use data taken by 40 strings of IceCube between 2008 April 5 and 2009 May 20. The triggered searches also use data taken by the 22-string configuration of IceCube operating between 2007 May 31 and 2008 April 5. The results from all four searches are compatible with a fluctuation of the background.
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| 29. |
- Abbasi, R., et al.
(författare)
-
Time-integrated Searches for Point-like Sources of Neutrinos with the 40-string IceCube Detector
- 2011
-
Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 732:1, s. 18-
-
Tidskriftsartikel (refereegranskat)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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| 30. |
- Braun, Matthias, et al.
(författare)
-
Changes of glacial front positions of Vestfonna (Nordaustlandet, Svalbard)
- 2011
-
Ingår i: Geografiska Annaler. Series A, Physical Geography. - : Informa UK Limited. - 0435-3676 .- 1468-0459. ; 93:4, s. 301-310
-
Tidskriftsartikel (refereegranskat)abstract
- Glaciers in Svalbard have shown considerable mass loss in recent years with a reported acceleration in the western and southern parts of the archipelago. However, for the ice cap Vestfonna, in northeastern Svalbard, climatic mass balance modelling has suggested almost balanced conditions over a period of nine years (2000–2009). A slightly positive geodetic mass balance (1990–2005) has been reported from a comparison of laser altimetry to older DEMs. A heterogeneous situation has been depicted for the various catchments, and hence changes in glacier extent can reveal additional information of glacier status, in particular when dealing with surge-type glaciers. We analysed a 34-year data record of multi-spectral satellite imagery in order to study changes in glacier frontal positions of the ice cap Vestfonna. A consistent pattern of almost steady retreat of the southern and north-eastern outlet glaciers of the ice cap is observed while Franklinbreen, the only major outlet glacier draining towards the north-west shows re-advance. This is consistent with an observed speed up and potential upcoming surge of this outlet. The glacier retreat on the southern coast also agrees with ICESat elevation change measurements. However, due to the glacier response time no direct relations between frontal retreat and surface mass balance can be drawn from the short observation period. The heterogeneous pattern of changes with on-going dynamic adjustments in some areas make the ice cap Vestfonna an ideal test site for future monitoring activities including novel techniques like differential interferometry from bi-static SAR systems.
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| 31. |
- Braun, Matthias, et al.
(författare)
-
Comparison of remote sensing derived glacier facies maps with distributed mass balance modelling at Engabreen, northern Norway
- 2007
-
Ingår i: Glacier Mass Balance Changes and Meltwater Discharge. - Wallingford : IAHS. - 9781901502398 ; , s. 126-134:318, s. 126-134
-
Konferensbidrag (refereegranskat)abstract
- Calibration and validation of glacier mass balance models typically rely on mass balance data derived from measurements at individual points, often along altitudinal gradients, thus neglecting much of the spatial variability of mass balance. Remote sensing data can provide useful additional spatially distributed information, e.g. on surface conditions such as bare ice area, firn cover extent, or snow. We developed a semi-automated procedure to derive glacier-facies maps from Landsat satellite images, and applied it to Engabreen, an outlet glacier from the Svartisen ice cap in northern Norway. These maps, discriminating between firn, snow and ice surfaces, are then used as a reference for mass balance modelling. Facies information shows a general agreement with the available few field observations and results obtained by distributed mass balance modelling. We conclude that Earth Observation products provide a powerful, although as yet poorly exploited tool, for calibration and validation of distributed mass balance models.
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| 32. |
- Braun, Matthias, et al.
(författare)
-
Corelease and differential exit via the fusion pore of GABA, serotonin, and ATP from LDCV in rat pancreatic beta cells
- 2007
-
Ingår i: Journal of General Physiology. - : Rockefeller University Press. - 0022-1295 .- 1540-7748. ; 129:3, s. 221-231
-
Tidskriftsartikel (refereegranskat)abstract
- The release gamma-aminobutyric acid (GABA) and ATP from rat beta cells was monitored using an electrophysiological assay based on overexpression GABAA or P2X2 receptor ion channels. Exocytosis of LDCVs, detected by carbon fiber amperometry of serotonin, correlated strongly (similar to 80%) with ATP release. The increase in membrane capacitance per ATP release event was 3.4 fF, close to the expected capacitance of an individual LDCV with a diameter of 0.3 mu m. ATP and GABA were coreleased with serotonin with the same probability. Immunogold electron microscopy revealed that similar to 15% of the LDCVs contain GABA. Prespike "pedestals," reflecting exit of granule constituents via the fusion pore, were less frequently observed for ATP than for serotonin or GABA and the relative amplitude (amplitude of foot compared to spike) was smaller: in some cases the ATP-dependent pedestal was missing entirely. An inward tonic current, not dependent on glucose and inhibited by the GABAA receptor antagonist SR95531, was observed in beta cells in clusters of islet cells. Noise analysis indicated that it was due to the activity of individual channels with a conductance of 30 pS, the same as expected for individual GABA(A) Cl- channels with the ionic gradients used. We conclude that (a) LDCVs accumulate ATP and serotonin; (b) regulated release of GABA can be accounted for by exocytosis of a subset of insulin-containing LDCVs; (c) the fusion pore of LDCVs exhibits selectivity and compounds are differentially released depending on their chemical properties (including size); and (d) a glucose-independent nonvesicular form of GABA release exists in beta cells.
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| 33. |
- Braun, Matthias, et al.
(författare)
-
GABAB-receptor activation inhibits exocytosis in rat pancreatic {beta}-cells by G-protein-dependent activation of calcineurin.
- 2004
-
Ingår i: Journal of Physiology. - : Wiley. - 1469-7793 .- 0022-3751. ; 559:2, s. 397-409
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated the regulation of hormone secretion from rat pancreatic islets by the GABAB receptors (GABABRs). Inclusion of the specific GABABR antagonist CGP 55845 in the extracellular medium increased glucose-stimulated insulin secretion 1.6-fold but did not affect the release of glucagon and somatostatin. Conversely, addition of the GABABR agonist baclofen inhibited glucose-stimulated insulin secretion by ∼60%. Using RT-PCR, transcription of GABABR1a-c,f and GABABR2 subunits was detected in β-cells. Measurements of membrane currents and cell capacitance were applied to single β-cells to investigate the mechanisms by which GABABR activation inhibits insulin secretion. In perforated-patch measurements, baclofen inhibited exocytosis elicited by 500-ms voltage-clamp depolarizations to 0 mV by ≤ 80% and voltage-gated Ca2+ entry by only ∼30%. Both effects were concentration-dependent with IC50 values of ∼2 μm. The inhibitory action of baclofen was abolished in the presence of CGP 55845. The ability of baclofen to suppress exocytosis was prevented by pre-treatment with pertussis toxin and by inclusion of GDPβS in the intracellular medium, and became irreversible in the presence of GTPγS as expected for a process involving inhibitory G-proteins (Gi/o-proteins). The inhibitory effect of baclofen resulted from activation of the serine/threonine protein phosphatase calcineurin and pre-treatment with cyclosporin A or intracellular application of calcineurin autoinhibitory peptide abolished the effect. Addition of baclofen had no effect on [Ca2+]i and electrical activity in glucose-stimulated β-cells. These data indicate that GABA released from β-cells functions as an autocrine inhibitor of insulin secretion in pancreatic islets and that the effect is principally due to direct suppression of exocytosis.
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| 34. |
- Braun, Matthias, et al.
(författare)
-
Regulated Exocytosis of GABA-containing Synaptic-like Microvesicles in Pancreatic {beta}-cells.
- 2004
-
Ingår i: Journal of General Physiology. - : Rockefeller University Press. - 0022-1295 .- 1540-7748. ; 123:3, s. 191-204
-
Tidskriftsartikel (refereegranskat)abstract
- We have explored whether {gamma}-aminobutyric acid (GABA) is released by regulated exocytosis of GABA-containing synaptic-like microvesicles (SLMVs) in insulin-releasing rat pancreatic ß-cells. To this end, ß-cells were engineered to express GABAA-receptor Cl--channels at high density using adenoviral infection. Electron microscopy indicated that the average diameter of the SLMVs is 90 nm, that every ß-cell contains ~3,500 such vesicles, and that insulin-containing large dense core vesicles exclude GABA. Quantal release of GABA, seen as rapidly activating and deactivating Cl--currents, was observed during membrane depolarizations from -70 mV to voltages beyond -40 mV or when Ca2+ was dialysed into the cell interior. Depolarization-evoked GABA release was suppressed when Ca2+ entry was inhibited using Cd2+. Analysis of the kinetics of GABA release revealed that GABA-containing vesicles can be divided into a readily releasable pool and a reserve pool. Simultaneous measurements of GABA release and cell capacitance indicated that exocytosis of SLMVs contributes ~1% of the capacitance signal. Mathematical analysis of the release events suggests that every SLMV contains 0.36 amol of GABA. We conclude that there are two parallel pathways of exocytosis in pancreatic ß-cells and that release of GABA may accordingly be temporally and spatially separated from insulin secretion. This provides a basis for paracrine GABAergic signaling within the islet.
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| 35. |
- De Marinis, Yang, et al.
(författare)
-
GLP-1 inhibits and adrenaline stimulates glucagon release by differential modulation of N- and L-type Ca2+ channel-dependent exocytosis.
- 2010
-
Ingår i: Cell Metabolism. - : Elsevier BV. - 1550-4131. ; 11:6, s. 543-553
-
Tidskriftsartikel (refereegranskat)abstract
- Glucagon secretion is inhibited by glucagon-like peptide-1 (GLP-1) and stimulated by adrenaline. These opposing effects on glucagon secretion are mimicked by low (1-10 nM) and high (10 muM) concentrations of forskolin, respectively. The expression of GLP-1 receptors in alpha cells is <0.2% of that in beta cells. The GLP-1-induced suppression of glucagon secretion is PKA dependent, is glucose independent, and does not involve paracrine effects mediated by insulin or somatostatin. GLP-1 is without much effect on alpha cell electrical activity but selectively inhibits N-type Ca(2+) channels and exocytosis. Adrenaline stimulates alpha cell electrical activity, increases [Ca(2+)](i), enhances L-type Ca(2+) channel activity, and accelerates exocytosis. The stimulatory effect is partially PKA independent and reduced in Epac2-deficient islets. We propose that GLP-1 inhibits glucagon secretion by PKA-dependent inhibition of the N-type Ca(2+) channels via a small increase in intracellular cAMP ([cAMP](i)). Adrenaline stimulates L-type Ca(2+) channel-dependent exocytosis by activation of the low-affinity cAMP sensor Epac2 via a large increase in [cAMP](i).
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| 36. |
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| 37. |
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| 38. |
- Eliasson, Lena, et al.
(författare)
-
Novel aspects of the molecular mechanisms controlling insulin secretion
- 2008
-
Ingår i: Journal of Physiology. - : Wiley. - 1469-7793 .- 0022-3751. ; 586:14, s. 3313-3324
-
Forskningsöversikt (refereegranskat)abstract
- Pancreatic beta-cells secrete insulin by Ca2+-dependent exocytosis of secretory granules. beta-cell exocytosis involves SNARE (soluble NSF-attachment protein receptor) proteins similar to those controlling neurotransmitter release and depends on the close association of L-type Ca2+ channels and granules. In most cases, the secretory granules fuse individually but there is ultrastructural and biophysical evidence of multivesicular exocytosis. Estimates of the secretory rate in beta-cells in intact islets indicate a release rate of similar to 15 granules per beta-cell per second, 100-fold higher than that observed in biochemical assays. Single-vesicle capacitance measurements reveal that the diameter of the fusion pore connecting the granule lumen with the exterior is similar to 1.4 nm. This is considerably smaller than the size of insulin and membrane fusion is therefore not obligatorily associated with release of the cargo, a feature that may contribute to the different rates of secretion detected by the biochemical and biophysical measurements. However, small molecules like ATP and GABA, which are stored together with insulin in the granules, are small enough to be released via the narrow fusion pore, which accordingly functions as a molecular sieve. We finally consider the possibility that defective fusion pore expansion accounts for the decrease in insulin secretion observed in pathophysiological states including long-term exposure to lipids.
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| 39. |
- Fuerst, Johannes Jakob, et al.
(författare)
-
Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard
- 2017
-
Ingår i: The Cryosphere. - : Copernicus GmbH. - 1994-0416 .- 1994-0424. ; 11:5, s. 2003-2032
-
Tidskriftsartikel (refereegranskat)abstract
- The basal topography is largely unknown beneath most glaciers and ice caps, and many attempts have been made to estimate a thickness field from other more accessible information at the surface. Here, we present a two-step reconstruction approach for ice thickness that solves mass conservation over single or several connected drainage basins. The approach is applied to a variety of test geometries with abundant thickness measurements including marine-and landterminating glaciers as well as a 2400 km(2) ice cap on Svalbard. The input requirements are kept to a minimum for the first step. In this step, a geometrically controlled, non-local flux solution is converted into thickness values relying on the shallow ice approximation (SIA). In a second step, the thickness field is updated along fast-flowing glacier trunks on the basis of velocity observations. Both steps account for available thickness measurements. Each thickness field is presented together with an error-estimate map based on a formal propagation of input uncertainties. These error estimates point out that the thickness field is least constrained near ice divides or in other stagnant areas. Withholding a share of the thickness measurements, error estimates tend to overestimate mismatch values in a median sense. We also have to accept an aggregate uncertainty of at least 25% in the reconstructed thickness field for glaciers with very sparse or no observations. For Vestfonna ice cap (VIC), a previous ice volume estimate based on the same measurement record as used here has to be corrected upward by 22 %. We also find that a 13% area fraction of the ice cap is in fact grounded below sea level. The former 5% estimate from a direct measurement interpolation exceeds an aggregate maximum range of 6-23% as inferred from the error estimates here.
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| 40. |
- Gilje, Patrik, et al.
(författare)
-
Plasma Levels of Liver-Specific miR-122 is Massively Increased in a Porcine Cardiogenic Shock Model and Attenuated by Hypothermia.
- 2012
-
Ingår i: Shock. - 1540-0514. ; 37, s. 234-238
-
Tidskriftsartikel (refereegranskat)abstract
- AIMS:: Tissue-specific circulating microRNAs are released into the blood after organ injury. In an ischemic porcine cardiogenic shock model we investigated the release pattern of cardiacspecific miR-208b and liver-specific miR-122 and assessed the effect of therapeutic hypothermia on their respective plasma levels. METHODS AND RESULTS:: Pigs were anesthetized and cardiogenic shock was induced by inflation of a PCI-balloon in the proximal LAD for 40 minutes followed by reperfusion. After fulfillment of the predefined shock criteria, the pigs were randomized to hypothermia (33°C, n=6) or normothermia (38°C, n=6). Circulating microRNAs were extracted from plasma and measured with quantitative real-time PCR. Tissue specificity was assessed by microRNA extraction from porcine tissues followed by quantitative real-time PCR. In vitro, the release of miR-122 from a cultured hepatocyte cell line exposed to either hypoxia or acidosis was assessed by real-time PCR. miR-122 was found to be highly liver specific whereas miR-208b was expressed exclusively in the heart. In the control group ischemic cardiogenic shock induced a 460.000-fold and a 63.000-fold increase in plasma levels of miR-122 (p<0.05) and miR-208b (p<0.05), respectively. Therapeutic hypothermia significantly diminished the increase of miR-122 compared to the normothermic group (p<0.005). In our model, hypothermia was initiated after coronary reperfusion and did neither affect myocardial damage as previously assessed by magnetic resonance imaging nor the plasma level of miR-208b. CONCLUSIONS:: Our results indicate that liver-specific miR-122 is released into the circulation in the setting of cardiogenic shock and that therapeutic hypothermia significantly reduces the levels of miR-122.
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| 41. |
- Kowal-Bielecka, Otylia, et al.
(författare)
-
Update of EULAR recommendations for the treatment of systemic sclerosis
- 2017
-
Ingår i: Annals of the Rheumatic Diseases. - : BMJ. - 0003-4967 .- 1468-2060. ; 76, s. 1327-1339
-
Tidskriftsartikel (refereegranskat)abstract
- The aim was to update the 2009 European League against Rheumatism (EULAR) recommendations for the treatment of systemic sclerosis (SSc), with attention to new therapeutic questions. Update of the previous treatment recommendations was performed according to EULAR standard operating procedures. The task force consisted of 32 SSc clinical experts from Europe and the USA, 2 patients nominated by the pan-European patient association for SSc (Federation of European Scleroderma Associations (FESCA)), a clinical epidemiologist and 2 research fellows. All centres from the EULAR Scleroderma Trials and Research group were invited to submit and select clinical questions concerning SSc treatment using a Delphi approach. Accordingly, 46 clinical questions addressing 26 different interventions were selected for systematic literature review. The new recommendations were based on the available evidence and developed in a consensus meeting with clinical experts and patients. The procedure resulted in 16 recommendations being developed (instead of 14 in 2009) that address treatment of several SSc-related organ complications: Raynaud's phenomenon (RP), digital ulcers (DUs), pulmonary arterial hypertension (PAH), skin and lung disease, scleroderma renal crisis and gastrointestinal involvement. Compared with the 2009 recommendations, the 2016 recommendations include phosphodiesterase type 5 (PDE-5) inhibitors for the treatment of SSc-related RP and DUs, riociguat, new aspects for endothelin receptor antagonists, prostacyclin analogues and PDE-5 inhibitors for SSc-related PAH. New recommendations regarding the use of fluoxetine for SSc-related RP and haematopoietic stem cell transplantation for selected patients with rapidly progressive SSc were also added. In addition, several comments regarding other treatments addressed in clinical questions and suggestions for the SSc research agenda were formulated. These updated data-derived and consensus-derived recommendations will help rheumatologists to manage patients with SSc in an evidence-based way. These recommendations also give directions for future clinical research in SSc.
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| 42. |
- Mahler, Jasmin, et al.
(författare)
-
Endogenous murine A beta increases amyloid deposition in APP23 but not in APPPS1 transgenic mice
- 2015
-
Ingår i: Neurobiology of Aging. - : Elsevier. - 0197-4580 .- 1558-1497. ; 36:7, s. 2241-2247
-
Tidskriftsartikel (refereegranskat)abstract
- Endogenous murine amyloid-beta peptide (A beta) is expressed in most A beta precursor protein (APP) transgenic mouse models of Alzheimers disease but its contribution to beta-amyloidosis remains unclear. We demonstrate similar to 35% increased cerebral A beta load in APP23 transgenic mice compared with age-matched APP23 mice on an App-null background. No such difference was found for the much faster A beta-depositing APPPS1 transgenic mouse model between animals with or without the murine App gene. Nevertheless, both APP23 and APPPS1 mice codeposited murine A beta, and immunoelectron microscopy revealed a tight association of murine A beta with human A beta fibrils. Deposition of murine A beta was considerably less efficient compared with the deposition of human A beta indicating a lower amyloidogenic potential of murine A beta in vivo. The amyloid dyes Pittsburgh Compound-B and pentamer formyl thiophene acetic acid did not differentiate between amyloid deposits consisting of human A beta and deposits of mixed human-murine A beta. Our data demonstrate a differential effect of murine A beta on human A beta deposition in different APP transgenic mice. The mechanistically complex interaction of human and mouse A beta may affect pathogenesis of the models and should be considered when models are used for translational preclinical studies.
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| 43. |
- Moeller, Marco, et al.
(författare)
-
Snowpack Characteristics of Vestfonna and De Geerfonna (Nordaustlandet, Svalbard) : A Spatiotemporal Analysis Based on Multiyear Snow-Pit Data
- 2011
-
Ingår i: Geografiska Annaler. Series A, Physical Geography. - : Informa UK Limited. - 0435-3676 .- 1468-0459. ; 93A:4, s. 273-285
-
Tidskriftsartikel (refereegranskat)abstract
- Extensive glaciological field measurements were carried out on the ice cap Vestfonna as well as on the minor ice body De Geerfonna (Nordaustlandet, Svalbard) within the framework of IPY Kinnvika. Field campaigns were conducted during the period 20072010 in spring (April/May) and summer (August). In this study we compile and present snow cover information obtained from 22 snow pits that were dug on Vestfonna during this period. Locations are along two transects on the northwestern, land terminating slope of the ice cap, on its central summit, Ahlmann Summit, and at a set of several other locations in the eastern and northern part of the ice cap. Snow-cover information acquired from four snow pits on adjacent De Geerfonna is also incorporated in this study. Field data are analysed regarding snow stratigraphy, snow density, snow hardness and snow temperature. Results reveal mean snow densities of around 400 kg m-3 for the snowpack of Vestfonna with no apparent spatial or interannual variability. A distinctly higher value of more than 450 kg m-3 was obtained for De Geerfonna. A spatial comparison of snow water equivalents above the previous end-of-summer surface serves for obtaining insights into the spatial distribution of snow accumulation across Vestfonna. Altitude was found to be the only significant spatial parameter for controlling snow accumulation across the ice cap.
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| 44. |
- Möller, Marco, et al.
(författare)
-
Climatic mass balance of the ice cap Vestfonna, Svalbard : A spatially distributed assessment using ERA-Interim and MODIS data
- 2011
-
Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 116:F3
-
Tidskriftsartikel (refereegranskat)abstract
- The ice cap Vestfonna in the northern Svalbard archipelago is one of the largest ice bodies of the European Arctic (similar to 2400 km(2)), but little is known about its mass balance. We model the climatic mass balance of the ice cap for the period September 2000 to August 2009 on a daily basis. Ablation is calculated by a spatially distributed temperature-radiation-index melt model. Air temperature forcing is provided by ERA-Interim data that is downscaled using data from an automatic weather station operated on the ice cap. Spatially distributed net shortwave radiation fluxes are obtained from standard trigonometric techniques combined with Moderate Resolution Imaging Spectroradiometer-based cloud cover and surface albedo information. Accumulation is derived from ERA-Interim precipitation data that are bias corrected and spatially distributed as a function of elevation. Refreezing is incorporated using the P(max) approach. Results indicate that mass balance years are characterized by short ablation seasons (June to August) and correspondingly longer accumulation periods (September to May). The modeled, annual climatic mass balance rate shows an almost balanced mean of -0.02 +/- 0.20 m w.e. yr(-1) (meters water equivalent per year) with an associated equilibrium line altitude of 383 +/- 54 m above sea level (mean +/- one standard deviation). The mean winter balance is +0.32 +/- 0.06 m w.e. yr(-1), and the mean summer balance -0.35 +/- 0.17 m w.e. yr(-1). Roughly one fourth of total surface ablation is retained by refreezing indicating that refreezing is an important component of the mass budget of Vestfonna.
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| 45. |
- Norell, Derrick, et al.
(författare)
-
Versatile in vitro system to study translocation and functional integration of bacterial outer membrane proteins
- 2014
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 5, s. 5396-
-
Tidskriftsartikel (refereegranskat)abstract
- Gram-negative bacteria use the type-V secretion pathway to expose proteins at their cell surface, many of which have virulence functions. Translocation of those proteins across the outer membrane occurs either by means of dedicated translocator proteins (two-partner secretion) or covalently fused translocator domains (autotransporters). Translocator proteins and translocator domains are beta-barrels requiring the beta-barrel assembly machinery (BAM) for membrane integration. However, the molecular details of their passage across the envelope and insertion into the outer membrane remain enigmatic, owing in part to the fact that in vitro systems are not available. Here we describe a versatile in vitro reconstitution system that faithfully reproduces both branches of the type-V secretion pathway and the assembly of beta-barrel outer membrane proteins. This system will allow an in-depth analysis of protein secretion across and integration into outer membranes.
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| 46. |
- Novotny, Renata, et al.
(författare)
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Conversion of Synthetic A beta to In Vivo Active Seeds and Amyloid Plaque Formation in a Hippocampal Slice Culture Model
- 2016
-
Ingår i: Journal of Neuroscience. - : SOC NEUROSCIENCE. - 0270-6474 .- 1529-2401. ; 36:18, s. 5084-5093
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Tidskriftsartikel (refereegranskat)abstract
- The aggregation of amyloid-beta peptide (A beta) inbrain is an early event and hallmark of Alzheimers disease (AD). We combined the advantages of in vitro and in vivo approaches to study cerebral beta-amyloidosis by establishing a long-term hippocampal slice culture(HSC) model. While no A beta deposition was noted in untreated HSCs of postnatal A beta precursor protein transgenic (APP tg) mice, A beta deposition emerged in HSCs when cultures were treated once with brain extract from aged APP tg mice and the culture medium was continuously supplemented with synthetic A beta. Seeded A beta deposition was also observed under the same conditions in HSCs derived from wild-type or App-null mice but in no comparable way when HSCs were fixed before cultivation. Both the nature of the brain extract and the synthetic A beta species determined the conformational characteristics of HSCA beta deposition. HSCA beta deposits induced a microglia response, spine loss, and neuritic dystrophy but no obvious neuron loss. Remarkably, in contrast to in vitro aggregated synthetic A beta, homogenates of A beta deposits containing HSCs induced cerebral beta-amyloidosis upon intracerebral inoculation into young APP tg mice. Our results demonstrate that a living cellular environment promotes the seeded conversion of synthetic A beta into a potent in vivo seeding-active form.
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| 47. |
- Popovski, Petar, et al.
(författare)
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EU FP7 INFSO-ICT-317669 METIS, D2.4 Proposed solutions for new radio access
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This deliverable represents the final report on the METIS radio link research. It provides a comprehensive and self-contained summary of all investigated technology components (TeCs), including evaluation results and conclusions on their potential for 5G. The METIS radio link research covers three main areas, which are considered key aspects for developing a self-contained air interface design for 5G: 1) Flexible air interface, 2) Waveforms, coding & modulation and transceiver design and 3) Multiple access, Medium Access Control (MAC) and Radio Resource Management (RRM). TeCs with similar research context and objectives have been grouped into clusters, whereof five have been selected as the most promising for 5G systems: From research area 1, TeC clusters providing key enablers for an air interface for ultra-dense networks (UDN) and for moving networks; from research area 2, multi-carrier transmission schemes with filtering; and from research area 3, novel access schemes for massive machine access as well as for non-orthogonal access.
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| 48. |
- Rorsman, Patrik, et al.
(författare)
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K-ATP-channels and glucagon secretion glucose-regulated
- 2008
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Ingår i: Trends in Endocrinology and Metabolism. - : Elsevier BV. - 1879-3061 .- 1043-2760. ; 19:8, s. 277-284
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Forskningsöversikt (refereegranskat)abstract
- Glucagon, secreted by the a-cells of the pancreatic islets, is the most important glucose-increasing hormone of the body. The precise regulation of glucagon release remains incompletely defined but has been proposed to involve release of inhibitory factors from neighbouring P-cells (paracrine control). However, the observation that glucose can regulate glucagon secretion under conditions when insulin secretion does not occur argues that the a-cell is also equipped with its own intrinsic (exerted within the a-cell itself) glucose sensing. Here we consider the possible mechanisms involved with a focus on ATP-regulated K+-channels and changes in a-cell membrane potential.
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| 49. |
- Rosengren, Anders, et al.
(författare)
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Reduced Insulin Exocytosis in Human Pancreatic β-cells With Gene Variants Linked to Type 2 Diabetes.
- 2012
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 61:7, s. 1726-1733
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Tidskriftsartikel (refereegranskat)abstract
- The majority of genetic risk variants for type 2 diabetes (T2D) affect insulin secretion, but the mechanisms through which they influence pancreatic islet function remain largely unknown. We functionally characterized human islets to determine secretory, biophysical, and ultrastructural features in relation to genetic risk profiles in diabetic and nondiabetic donors. Islets from donors with T2D exhibited impaired insulin secretion, which was more pronounced in lean than obese diabetic donors. We assessed the impact of 14 disease susceptibility variants on measures of glucose sensing, exocytosis, and structure. Variants near TCF7L2 and ADRA2A were associated with reduced glucose-induced insulin secretion, whereas susceptibility variants near ADRA2A, KCNJ11, KCNQ1, and TCF7L2 were associated with reduced depolarization-evoked insulin exocytosis. KCNQ1, ADRA2A, KCNJ11, HHEX/IDE, and SLC2A2 variants affected granule docking. We combined our results to create a novel genetic risk score for β-cell dysfunction that includes aberrant granule docking, decreased Ca(2+) sensitivity of exocytosis, and reduced insulin release. Individuals with a high risk score displayed an impaired response to intravenous glucose and deteriorating insulin secretion over time. Our results underscore the importance of defects in β-cell exocytosis in T2D and demonstrate the potential of cellular phenotypic characterization in the elucidation of complex genetic disorders.
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| 50. |
- Rosmarin, Dan, et al.
(författare)
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Genetic Markers of Toxicity From Capecitabine and Other Fluorouracil-Based Regimens : Investigation in the QUASAR2 Study, Systematic Review, and Meta-Analysis
- 2014
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Ingår i: Journal of Clinical Oncology. - 0732-183X .- 1527-7755. ; 32:10, s. 1031-1039
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Fluourouracil (FU) is a mainstay of chemotherapy, although toxicities are common. Genetic biomarkers have been used to predict these adverse events, but their utility is uncertain.PATIENTS AND METHODS: We tested candidate polymorphisms identified from a systematic literature search for associations with capecitabine toxicity in 927 patients with colorectal cancer in the Quick and Simple and Reliable trial (QUASAR2). We then performed meta-analysis of QUASAR2 and 16 published studies (n = 4,855 patients) to examine the polymorphisms in various FU monotherapy and combination therapy regimens.RESULTS: Global capecitabine toxicity (grades 0/1/2 v grades 3/4/5) was associated with the rare, functional DPYD alleles 2846T>A and *2A (combined odds ratio, 5.51; P = .0013) and with the common TYMS polymorphisms 5'VNTR2R/3R and 3'UTR 6bp ins-del (combined odds ratio, 1.31; P = 9.4 × 10(-6)). There was weaker evidence that these polymorphisms predict toxicity from bolus and infusional FU monotherapy. No good evidence of association with toxicity was found for the remaining polymorphisms, including several currently included in predictive kits. No polymorphisms were associated with toxicity in combination regimens.CONCLUSION: A panel of genetic biomarkers for capecitabine monotherapy toxicity would currently comprise only the four DPYD and TYMS variants above. We estimate this test could provide 26% sensitivity, 86% specificity, and 49% positive predictive value-better than most available commercial kits, but suboptimal for clinical use. The test panel might be extended to include additional, rare DPYD variants functionally equivalent to *2A and 2846A, though insufficient evidence supports its use in bolus, infusional, or combination FU. There remains a need to identify further markers of FU toxicity for all regimens.
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