| 1. |
- Abazov, V. M., et al.
(författare)
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The upgraded DO detector
- 2006
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 565:2, s. 463-537
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Tidskriftsartikel (refereegranskat)abstract
- The DO experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid -argon calorimeters and central muon detector, remaining from Run 1, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DO.
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| 2. |
- Abdo, A. A., et al.
(författare)
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FERMI/LARGE AREA TELESCOPE BRIGHT GAMMA-RAY SOURCE LIST
- 2009
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Ingår i: Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 183:1, s. 46-66
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Tidskriftsartikel (refereegranskat)abstract
- Following its launch in 2008 June, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in three months produced a deeper and better resolved map of the gamma-ray sky than any previous space mission. We present here initial results for energies above 100 MeV for the 205 most significant (statistical significance greater than similar to 10 sigma) gamma-ray sources in these data. These are the best characterized and best localized point-like (i.e., spatially unresolved) gamma-ray sources in the early mission data.
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| 3. |
- Abdo, A. A., et al.
(författare)
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Measurement of the Cosmic Ray e(+)+e(-) Spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:Article number: 181101
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Tidskriftsartikel (refereegranskat)abstract
- Designed as a high-sensitivity gamma-ray observatory, the Fermi Large Area Telescope is also an electron detector with a large acceptance exceeding 2 m(2) sr at 300 GeV. Building on the gamma-ray analysis, we have developed an efficient electron detection strategy which provides sufficient background rejection for measurement of the steeply falling electron spectrum up to 1 TeV. Our high precision data show that the electron spectrum falls with energy as E-3.0 and does not exhibit prominent spectral features. Interpretations in terms of a conventional diffusive model as well as a potential local extra component are briefly discussed.
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| 4. |
- Abdo, A. A., et al.
(författare)
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A Population of Gamma-Ray Millisecond Pulsars Seen with the Fermi Large Area Telescope
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 325:5942, s. 848-852
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Tidskriftsartikel (refereegranskat)abstract
- Pulsars are born with subsecond spin periods and slow by electromagnetic braking for several tens of millions of years, when detectable radiation ceases. A second life can occur for neutron stars in binary systems. They can acquire mass and angular momentum from their companions, to be spun up to millisecond periods and begin radiating again. We searched Fermi Large Area Telescope data for pulsations from all known millisecond pulsars (MSPs) outside of globular clusters, using rotation parameters from radio telescopes. Strong gamma-ray pulsations were detected for eight MSPs. The gamma-ray pulse profiles and spectral properties resemble those of young gamma-ray pulsars. The basic emission mechanism seems to be the same for MSPs and young pulsars, with the emission originating in regions far from the neutron star surface.
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| 5. |
- Abdo, A. A., et al.
(författare)
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Fermi/LAT observations of LS 5039
- 2009
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Ingår i: Astrophysical Journal Letters. - 0571-7248 .- 2041-8205. ; 706:1, s. L56-L61
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Tidskriftsartikel (refereegranskat)abstract
- The first results from observations of the high-mass X-ray binary LS 5039 using the Fermi Gamma-ray Space Telescope data between 2008 August and 2009 June are presented. Our results indicate variability that is consistent with the binary period, with the emission being modulated with a period of 3.903 ± 0.005 days; the first detection of this modulation at GeV energies. The light curve is characterized by a broad peak around superior conjunction in agreement with inverse Compton scattering models. The spectrum is represented by a power law with an exponential cutoff, yielding an overall flux (100 MeV-300 GeV) of 4.9 ± 0.5(stat) ± 1.8(syst) ×10–7 photon cm–2 s–1, with a cutoff at 2.1 ± 0.3(stat) ± 1.1(syst) GeV and photon index Γ = 1.9 ± 0.1(stat) ± 0.3(syst). The spectrum is observed to vary with orbital phase, specifically between inferior and superior conjunction. We suggest that the presence of a cutoff in the spectrum may be indicative of magnetospheric emission similar to the emission seen in many pulsars by Fermi.
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| 6. |
- Abdo, A. A., et al.
(författare)
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PULSED GAMMA-RAYS FROM PSR J2021+3651 WITH THE FERMI LARGE AREA TELESCOPE
- 2009
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 700:2, s. 1059-1066
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Tidskriftsartikel (refereegranskat)abstract
- We report the detection of pulsed gamma-rays from the young, spin-powered radio pulsar PSR J2021+3651 using data acquired with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST). The light curve consists of two narrow peaks of similar amplitude separated by 0.468 +/- 0.002 in phase. The first peak lags the maximum of the 2 GHz radio pulse by 0.162 +/- 0.004 +/- 0.01 in phase. The integral gamma-ray photon flux above 100 MeV is (56 +/- 3 +/- 11) x 10(-8) cm(-2) s(-1). The photon spectrum is well described by an exponentially cut-off power law of the form dF/dE = kE(-Gamma)e((-E/Ec)), where the energy E is expressed in GeV. The photon index is Gamma = 1.5 +/- 0.1 +/- 0.1 and the exponential cut-off is E-c = 2.4 +/- 0.3 +/- 0.5 GeV. The first uncertainty is statistical and the second is systematic. The integral photon flux of the bridge is approximately 10% of the pulsed emission, and the upper limit on off-pulse gamma-ray emission from a putative pulsar wind nebula is < 10% of the pulsed emission at the 95% confidence level. Radio polarization measurements yield a rotation measure of RM = 524 +/- 4 rad m(-2) but a poorly constrained magnetic geometry. Re-analysis of Chandra X-ray Observatory data enhanced the significance of the weak X-ray pulsations, and the first peak is roughly phase aligned with the first gamma-ray peak. We discuss the emission region and beaming geometry based on the shape and spectrum of the gamma-ray light curve combined with radio and X-ray measurements, and the implications for the pulsar distance. Gamma-ray emission from the polar cap region seems unlikely for this pulsar.
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| 7. |
- Emerging Risk Factors, Collaboration, et al.
(författare)
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The Emerging Risk Factors Collaboration: analysis of individual data on lipid, inflammatory and other markers in over 1.1 million participants in 104 prospective studies of cardiovascular diseases
- 2007
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Ingår i: Eur J Epidemiol. - 0393-2990. ; 22:12, s. 839-69
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Tidskriftsartikel (refereegranskat)abstract
- Many long-term prospective studies have reported on associations of cardiovascular diseases with circulating lipid markers and/or inflammatory markers. Studies have not, however, generally been designed to provide reliable estimates under different circumstances and to correct for within-person variability. The Emerging Risk Factors Collaboration has established a central database on over 1.1 million participants from 104 prospective population-based studies, in which subsets have information on lipid and inflammatory markers, other characteristics, as well as major cardiovascular morbidity and cause-specific mortality. Information on repeat measurements on relevant characteristics has been collected in approximately 340,000 participants to enable estimation of and correction for within-person variability. Re-analysis of individual data will yield up to approximately 69,000 incident fatal or nonfatal first ever major cardiovascular outcomes recorded during about 11.7 million person years at risk. The primary analyses will involve age-specific regression models in people without known baseline cardiovascular disease in relation to fatal or nonfatal first ever coronary heart disease outcomes. This initiative will characterize more precisely and in greater detail than has previously been possible the shape and strength of the age- and sex-specific associations of several lipid and inflammatory markers with incident coronary heart disease outcomes (and, secondarily, with other incident cardiovascular outcomes) under a wide range of circumstances. It will, therefore, help to determine to what extent such associations are independent from possible confounding factors and to what extent such markers (separately and in combination) provide incremental predictive value.
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| 8. |
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| 9. |
- Urowitz, M B, et al.
(författare)
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Clinical manifestations and coronary artery disease risk factors at diagnosis of systemic lupus erythematosus: data from an international inception cohort
- 2007
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Ingår i: Lupus. - : SAGE Publications. - 0961-2033 .- 1477-0962. ; 16:9, s. 731-735
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Tidskriftsartikel (refereegranskat)abstract
- Systemic Lupus International Collaborating Clinics (SLICC) comprises 27 centres from 11 countries. An inception cohort of 918 SLE patients has been assembled according to a standardized protocol between 2000 and 2006. Clinical features, classic coronary artery disease (CAD) risk factors, as well as other potential risk factors were collected. Of the 918 patients 89% were females, and of multi racial origin. Less than half the patients were living in a permanent relationship, 58% had post secondary education and 51% were employed. Eight percent had family history of SLE. At enrolment, with at mean age of diagnosis of 34.5 years, a significant number of patients already had CAD risk factors, such as hypertension (33%) and hypercholesterolemia (36%). Only 15% of the patients were postmenopausal, 16% were current smokers and 3.6% had diabetes at entry to the SLICC-RAS (Registry for Atherosclerosis). A number of patients in this multi-racial, multi-ethnic inception cohort of lupus patients have classic CAD risk factors within a mean of 5.4 months from diagnosis. This cohort will be increased to 1500 patients to be followed yearly for 10 years. This will provide a unique opportunity to evaluate risk factors for accelerated atherosclerosis in SLE.
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| 10. |
- Hanly, J G, et al.
(författare)
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Autoantibodies and neuropsychiatric events at the time of systemic lupus erythematosus diagnosis
- 2008
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Ingår i: Arthritis and Rheumatism. - : Wiley. - 1529-0131 .- 0004-3591. ; 58:3, s. 843-853
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To examine, in an inception cohort of systemic lupus erythematosus (SLE) patients, the association between neuropsychiatric (NP) events and anti-ribosomal P (anti-P), antiphospholipid (lupus anticoagulant [LAC], anticardiolipin), anti-beta 2-glycoprotein I, and anti-NR2 glutamate receptor antibodies. Methods. NP events were identified using the American College of Rheumatology case definitions and clustered into central/peripheral and diffuse/focal events. Attribution of NP events to SLE was determined using decision rules of differing stringency. Autoantibodies were measured without knowledge of NP events or their attribution. Results. Four hundred twelve patients were studied (87.4% female; mean +/- SD age 34.9 +/- 13.5 years, mean +/- SD disease duration 5.0 +/- 4.2 months). There were 214 NP events in 133 patients (32.3%). The proportion of NP events attributed to SLE varied from 15% to 36%. There was no association between autoantibodies and NP events overall. However, the frequency of anti-P antibodies in patients with central NP events attributed to SLE was 4 of 20 (20%), versus 3 of 107 (2.8%) in patients with other NP events and 24 of 279 (8.6%) in those with no NP events (P = 0.04). Among patients with diffuse NP events, 3 of 11 had anti-P antibodies (27%), compared with 4 of 111 patients with other NP events (3.6%) and 24 of 279 of those with no NP events (8.6%) (P 0.02). Specific clinical-serologic associations were found between anti-P and psychosis attributed to SLE (P = 0.02) and between LAC and cerebrovascular disease attributed to SLE (P = 0.038). There was no significant association between other autoantibodies and NP events. Conclusion. Clinically distinct NP events attributed to SLE and occurring around the time of diagnosis were found to be associated with anti-P antibodies and LAC. This Suggests that there are different autoimmune pathogenetic mechanisms, although low sensitivity limits the clinical application of testing for these antibodies.
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