| 1. |
- Ackermann, M., et al.
(författare)
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MULTI-WAVELENGTH OBSERVATIONS OF BLAZAR AO 0235+164 IN THE 2008-2009 FLARING STATE
- 2012
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 751:2
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Tidskriftsartikel (refereegranskat)abstract
- The blazarAO 0235+164 (z=0.94) has been one of the most active objects observed by Fermi Large Area Telescope (LAT) since its launch in Summer 2008. In addition to the continuous coverage by Fermi, contemporaneous observations were carried out from the radio to gamma-ray bands between 2008 September and 2009 February. In this paper, we summarize the rich multi-wavelength data collected during the campaign (including F-GAMMA, GASP-WEBT, Kanata, OVRO, RXTE, SMARTS, Swift, and other instruments), examine the cross-correlation between the light curves measured in the different energy bands, and interpret the resulting spectral energy distributions in the context of well-known blazar emission models. We find that the gamma-ray activity is well correlated with a series of near-IR/optical flares, accompanied by an increase in the optical polarization degree. On the other hand, the X-ray light curve shows a distinct 20 day high state of unusually soft spectrum, which does not match the extrapolation of the optical/UV synchrotron spectrum. We tentatively interpret this feature as the bulk Compton emission by cold electrons contained in the jet, which requires an accretion disk corona with an effective covering factor of 19% at a distance of 100 R-g. We model the broadband spectra with a leptonic model with external radiation dominated by the infrared emission from the dusty torus.
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| 2. |
- Thompson, Paul M., et al.
(författare)
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The ENIGMA Consortium : large-scale collaborative analyses of neuroimaging and genetic data
- 2014
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Ingår i: BRAIN IMAGING BEHAV. - : Springer Science and Business Media LLC. - 1931-7557 .- 1931-7565. ; 8:2, s. 153-182
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Tidskriftsartikel (refereegranskat)abstract
- The Enhancing NeuroImaging Genetics through Meta-Analysis (ENIGMA) Consortium is a collaborative network of researchers working together on a range of large-scale studies that integrate data from 70 institutions worldwide. Organized into Working Groups that tackle questions in neuroscience, genetics, and medicine, ENIGMA studies have analyzed neuroimaging data from over 12,826 subjects. In addition, data from 12,171 individuals were provided by the CHARGE consortium for replication of findings, in a total of 24,997 subjects. By meta-analyzing results from many sites, ENIGMA has detected factors that affect the brain that no individual site could detect on its own, and that require larger numbers of subjects than any individual neuroimaging study has currently collected. ENIGMA's first project was a genome-wide association study identifying common variants in the genome associated with hippocampal volume or intracranial volume. Continuing work is exploring genetic associations with subcortical volumes (ENIGMA2) and white matter microstructure (ENIGMA-DTI). Working groups also focus on understanding how schizophrenia, bipolar illness, major depression and attention deficit/hyperactivity disorder (ADHD) affect the brain. We review the current progress of the ENIGMA Consortium, along with challenges and unexpected discoveries made on the way.
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| 3. |
- Bower, G. C., et al.
(författare)
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THE ALLEN TELESCOPE ARRAY Pi GHz SKY SURVEY. I. SURVEY DESCRIPTION AND STATIC CATALOG RESULTS FOR THE BOOTES FIELD
- 2010
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 725:2, s. 1792-1804
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Tidskriftsartikel (refereegranskat)abstract
- The Pi GHz Sky Survey (PiGSS) is a key project of the Allen Telescope Array. PiGSS is a 3.1 GHz survey of radio continuum emission in the extragalactic sky with an emphasis on synoptic observations that measure the static and time-variable properties of the sky. During the 2.5 year campaign, PiGSS will twice observe similar to 250,000 radio sources in the 10,000 deg(2) region of the sky with b > 30 degrees to an rms sensitivity of similar to 1 mJy. Additionally, sub-regions of the sky will be observed multiple times to characterize variability on timescales of days to years. We present here observations of a 10 deg(2) region in the Bootes constellation overlapping the NOAO Deep Wide Field Survey field. The PiGSS image was constructed from 75 daily observations distributed over a 4 month period and has an rms flux density between 200 and 250 mu Jy. This represents a deeper image by a factor of 4-8 than we will achieve over the entire 10,000 deg(2). We provide flux densities, source sizes, and spectral indices for the 425 sources detected in the image. We identify similar to 100 new flat-spectrum radio sources; we project that when completed PiGSS will identify 10(4) flat-spectrum sources. We identify one source that is a possible transient radio source. This survey provides new limits on faint radio transients and variables with characteristic durations of months.
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| 4. |
- Aghion, S., et al.
(författare)
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A moiré deflectometer for antimatter
- 2014
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- The precise measurement of forces is one way to obtain deep insight into the fundamental interactions present in nature. In the context of neutral antimatter, the gravitational interaction is of high interest, potentially revealing new forces that violate the weak equivalence principle. Here we report on a successful extension of a tool from atom optics—the moiré deflectometer—for a measurement of the acceleration of slow antiprotons. The setup consists of two identical transmission gratings and a spatially resolving emulsion detector for antiproton annihilations. Absolute referencing of the observed antimatter pattern with a photon pattern experiencing no deflection allows the direct inference of forces present. The concept is also straightforwardly applicable to antihydrogen measurements as pursued by the AEgIS collaboration. The combination of these very different techniques from high energy and atomic physics opens a very promising route to the direct detection of the gravitational acceleration of neutral antimatter.
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| 5. |
- Ariga, T., et al.
(författare)
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Measuring GBAR with emulsion detector
- 2014
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Ingår i: International Journal of Modern Physics, Conference Series. - : World Scientific. - 2010-1945. ; 30
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Tidskriftsartikel (refereegranskat)
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| 6. |
- Croft, S., et al.
(författare)
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THE ALLEN TELESCOPE ARRAY TWENTY-CENTIMETER SURVEY-A 690 DEG(2), 12 EPOCH RADIO DATA SET. I. CATALOG AND LONG-DURATION TRANSIENT STATISTICS
- 2010
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Ingår i: Astrophysical Journal. - 1538-4357 .- 0004-637X. ; 719:1, s. 45-58
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Tidskriftsartikel (refereegranskat)abstract
- We present the Allen Telescope Array Twenty-centimeter Survey (ATATS), a multi-epoch (12 visits), 690 deg(2) radio image and catalog at 1.4 GHz. The survey is designed to detect rare, very bright transients as well as to verify the capabilities of the ATA to form large mosaics. The combined image using data from all 12 ATATS epochs has rms noise sigma = 3.94 mJy beam(-1) and dynamic range 180, with a circular beam of 150 '' FWHM. It contains 4408 sources to a limiting sensitivity of 5 sigma = 20 mJy beam(-1). We compare the catalog generated from this 12 epoch combined image to the NRAO VLA Sky Survey (NVSS), a legacy survey at the same frequency, and find that we can measure source positions to better than similar to 20 ''. For sources above the ATATS completeness limit, the median flux density is 97% of the median value for matched NVSS sources, indicative of an accurate overall flux calibration. We examine the effects of source confusion due to the effects of differing resolution between ATATS and NVSS on our ability to compare flux densities. We detect no transients at flux densities greater than 40 mJy in comparison with NVSS and place a 2 sigma upper limit of 0.004 deg(-2) on the transient rate for such sources. These results suggest that the greater than or similar to 1 Jy transients reported by Matsumara et al. may not be true transients, but rather variable sources at their flux density threshold.
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| 7. |
- Ferrari, Raffaele, et al.
(författare)
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Frontotemporal dementia and its subtypes: a genome-wide association study.
- 2014
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Ingår i: Lancet Neurology. - 1474-4465. ; 13:7, s. 686-699
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Tidskriftsartikel (refereegranskat)abstract
- Frontotemporal dementia (FTD) is a complex disorder characterised by a broad range of clinical manifestations, differential pathological signatures, and genetic variability. Mutations in three genes-MAPT, GRN, and C9orf72-have been associated with FTD. We sought to identify novel genetic risk loci associated with the disorder.
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| 8. |
- Fretwell, P., et al.
(författare)
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Bedmap2 : improved ice bed, surface and thickness datasets for Antarctica
- 2013
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Ingår i: The Cryosphere. - : Copernicus GmbH. - 1994-0416 .- 1994-0424. ; 7:1, s. 375-393
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Tidskriftsartikel (refereegranskat)abstract
- We present Bedmap2, a new suite of gridded products describing surface elevation, ice-thickness and the seafloor and subglacial bed elevation of the Antarctic south of 60 degrees S. We derived these products using data from a variety of sources, including many substantial surveys completed since the original Bedmap compilation (Bedmap1) in 2001. In particular, the Bedmap2 ice thickness grid is made from 25 million measurements, over two orders of magnitude more than were used in Bedmap1. In most parts of Antarctica the subglacial landscape is visible in much greater detail than was previously available and the improved data-coverage has in many areas revealed the full scale of mountain ranges, valleys, basins and troughs, only fragments of which were previously indicated in local surveys. The derived statistics for Bedmap2 show that the volume of ice contained in the Antarctic ice sheet (27 million km(3)) and its potential contribution to sea-level rise (58 m) are similar to those of Bedmap1, but the mean thickness of the ice sheet is 4.6% greater, the mean depth of the bed beneath the grounded ice sheet is 72m lower and the area of ice sheet grounded on bed below sea level is increased by 10 %. The Bedmap2 compilation highlights several areas beneath the ice sheet where the bed elevation is substantially lower than the deepest bed indicated by Bedmap1. These products, along with grids of data coverage and uncertainty, provide new opportunities for detailed modelling of the past and future evolution of the Antarctic ice sheets.
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| 9. |
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| 10. |
- Peters, W., et al.
(författare)
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Seven years of recent European net terrestrial carbon dioxide exchange constrained by atmospheric observations
- 2010
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 16:4, s. 1317-1337
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Tidskriftsartikel (refereegranskat)abstract
- We present an estimate of net ecosystem exchange (NEE) of CO2 in Europe for the years 2001-2007. It is derived with a data assimilation that uses a large set of atmospheric CO2 mole fraction observations (similar to 70 000) to guide relatively simple descriptions of terrestrial and oceanic net exchange, while fossil fuel and fire emissions are prescribed. Weekly terrestrial sources and sinks are optimized (i.e., a flux inversion) for a set of 18 large ecosystems across Europe in which prescribed climate, weather, and surface characteristics introduce finer scale gradients. We find that the terrestrial biosphere in Europe absorbed a net average of -165 Tg C yr-1 over the period considered. This uptake is predominantly in non-EU countries, and is found in the northern coniferous (-94 Tg C yr-1) and mixed forests (-30 Tg C yr-1) as well as the forest/field complexes of eastern Europe (-85 Tg C yr-1). An optimistic uncertainty estimate derived using three biosphere models suggests the uptake to be in a range of -122 to -258 Tg C yr-1, while a more conservative estimate derived from the a-posteriori covariance estimates is -165 +/- 437 Tg C yr-1. Note, however, that uncertainties are hard to estimate given the nature of the system and are likely to be significantly larger than this. Interannual variability in NEE includes a reduction in uptake due to the 2003 drought followed by 3 years of more than average uptake. The largest anomaly of NEE occurred in 2005 concurrent with increased seasonal cycles of observed CO2. We speculate these changes to result from the strong negative phase of the North Atlantic Oscillation in 2005 that lead to favorable summer growth conditions, and altered horizontal and vertical mixing in the atmosphere. All our results are available through http://www.carbontracker.eu.
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