| 61. |
- Madsen, N, et al.
(författare)
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Search for trapped antihydrogen in ALPHA
- 2011
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Ingår i: Canadian journal of physics (Print). - 0008-4204 .- 1208-6045. ; 89:1, s. 7-16
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Tidskriftsartikel (refereegranskat)abstract
- Antihydrogen spectroscopy promises precise tests of the symmetry of matter and antimatter, and can possibly offer new insights into the baryon asymmetry of the universe. Antihydrogen is, however, difficult to synthesize and is produced only in small quantities. The ALPHA collaboration is therefore pursuing a path towards trapping cold antihydrogen to permit the use of precision atomic physics tools to carry out comparisons of antihydrogen and hydrogen. ALPHA has addressed these challenges. Control of the plasma sizes has helped to lower the influence of the multipole field used in the neutral atom trap, and thus lowered the temperature of the created atoms. Finally, the first systematic attempt to identify trapped antihydrogen in our system is discussed. This discussion includes special techniques for fast release of the trapped anti-atoms, as well as a silicon vertex detector to identify antiproton annihilations. The silicon detector reduces the background of annihilations, including background from antiprotons that can be mirror trapped in the fields of the neutral atom trap. A description of how to differentiate between these events and those resulting from trapped antihydrogen atoms is also included.
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| 62. |
- Van Der Werf, D. P., et al.
(författare)
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Antimatter transport processes
- 2010
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Ingår i: AAPS Journal. - : IOP Publishing. - 1550-7416. ; 257:1
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Tidskriftsartikel (refereegranskat)abstract
- A comparison of the 1S-2S transitions of hydrogen and antihydrogen will yield a stringent test of CPT conservation. Necessarily, the antihydrogen atoms need to be trapped to perform high precision spectroscopy measurements. Therefore, an approximately 0.75 T deep neutral atom trap, equivalent to about 0.5 K for ground state (anti)hydrogen atoms, has been superimposed on a Penning-Malmberg trap in which the anti-atoms are formed. The antihydrogen atoms are produced following a number of steps. A bunch of antiprotons from the CERN Antiproton Decelerator is caught in a Penning-Malmberg trap and subsequently sympathetically cooled and then compressed using rotating wall electric fields. A positron plasma, formed in a separate accumulator, is transported to the main system and also compressed. Antihydrogen atoms are then formed by mixing the antiprotons and positrons. The velocity of the anti-atoms, and their binding energies, will strongly depend on the initial conditions of the constituent particles, for example their temperatures and densities, and on the details of the mixing process. In this paper the complete lifecycle of antihydrogen atoms will be presented, starting with the production of the constituent antiparticles and the description of the manipulations necessary to prepare them appropriately for antihydrogen formation. The latter will also be described, as will the possible fates of the anti-atoms.
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| 63. |
- Andresen, G. B., et al.
(författare)
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Evaporative Cooling of Antiprotons to Cryogenic Temperatures
- 2010
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 105:1, s. 013003-
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Tidskriftsartikel (refereegranskat)abstract
- We report the application of evaporative cooling to clouds of trapped antiprotons, resulting in plasmas with measured temperature as low as 9 K. We have modeled the evaporation process for charged particles using appropriate rate equations. Good agreement between experiment and theory is observed, permitting prediction of cooling efficiency in future experiments. The technique opens up new possibilities for cooling of trapped ions and is of particular interest in antiproton physics, where a precise CPT test on trapped antihydrogen is a long-standing goal.
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| 64. |
- Butler, E., et al.
(författare)
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Towards antihydrogen trapping and spectroscopy at ALPHA
- 2011
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Ingår i: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 199:1, s. 39-48
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Tidskriftsartikel (refereegranskat)abstract
- Spectroscopy of antihydrogen has the potential to yield high-precision tests of the CPT theorem and shed light on the matter-antimatter imbalance in the Universe. The ALPHA antihydrogen trap at CERN’s Antiproton Decelerator aims to prepare a sample of antihydrogen atoms confined in an octupole-based Ioffe trap and to measure the frequency of several atomic transitions. We describe our techniques to directly measure the antiproton temperature and a new technique to cool them to below 10 K. We also show how our unique position-sensitive annihilation detector provides us with a highly sensitive method of identifying antiproton annihilations and effectively rejecting the cosmic-ray background.
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| 65. |
- Helgadottir, Anna, et al.
(författare)
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Apolipoprotein(a) Genetic Sequence Variants Associated With Systemic Atherosclerosis and Coronary Atherosclerotic Burden But Not With Venous Thromboembolism
- 2012
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Ingår i: Journal of the American College of Cardiology. - : Elsevier BV. - 0735-1097 .- 1558-3597. ; 60:8, s. 722-729
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Tidskriftsartikel (refereegranskat)abstract
- Objectives The purpose of this study is investigate the effects of variants in the apolipoprotein(a) gene (LPA) on vascular diseases with different atherosclerotic and thrombotic components. Background It is unclear whether the LPA variants rs10455872 and rs3798220, which correlate with lipoprotein(a) levels and coronary artery disease (CAD), confer susceptibility predominantly via atherosclerosis or thrombosis. Methods The 2 LPA variants were combined and examined as LPA scores for the association with ischemic stroke (and TOAST [Trial of Org 10172 in Acute Stroke Treatment] subtypes) (effective sample size [n(e)] = 9,396); peripheral arterial disease (n(e) = 5,215); abdominal aortic aneurysm (ne = 4,572); venous thromboembolism (ne = 4,607); intracranial aneurysm (ne = 1,328); CAD (n(e) = 12,716), carotid intima-media thickness (n = 3,714), and angiographic CAD severity (n = 5,588). Results LPA score was associated with ischemic stroke subtype large artery atherosclerosis (odds ratio [OR]: 1.27; p = 6.7 X 10(-4)), peripheral artery disease (OR: 1.47; p = 2.9 x 10(-14)), and abdominal aortic aneurysm (OR: 1.23; p = 6.0 x 10(-5)), but not with the ischemic stroke subtypes cardioembolism (OR: 1.03; p = 0.69) or small vessel disease (OR: 1.06; p = 0.52). Although the LPA variants were not associated with carotid intima-media thickness, they were associated with the number of obstructed coronary vessels (p = 4.8 x 10(-12)). Furthermore, CAD cases carrying LPA risk variants had increased susceptibility to atherosclerotic manifestations outside of the coronary tree (OR: 1.26; p = 0.0010) and had earlier onset of CAD (-1.58 years/allele; p = 8.2 x 10(-8)) than CAD cases not carrying the risk variants. There was no association of LPA score with venous thromboembolism (OR: 0.97; p = 0.63) or intracranial aneurysm (OR: 0.85; p = 0.15). Conclusions LPA sequence variants were associated with atherosclerotic burden, but not with primarily thrombotic phenotypes. (J Am Coll Cardiol 2012; 60: 722-9) (C) 2012 by the American College of Cardiology Foundation
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| 66. |
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| 67. |
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| 68. |
- Glasner, J, et al.
(författare)
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A small molecule alpha(4)beta(1) antagonist prevents development of murine Lyme arthritis without affecting protective immunity
- 2005
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Ingår i: Journal of Immunology. - 1550-6606. ; 175:7, s. 4724-4734
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Tidskriftsartikel (refereegranskat)abstract
- After infection with Borrelia burgdorferi, humans and mice under certain conditions develop arthritis. Initiation of inflammation is dependent on the migration of innate immune cells to the site of infection, controlled by interactions of a variety of adhesion molecules. In this study, we used the newly synthesized compound S18407, which is a prodrug of the active drug S16197, to analyze the functional importance of alpha(4)beta(1)-dependent cell adhesion for the development of arthritis and for the antibacterial immune response. S16197 is shown to interfere specifically with the binding of alpha(4)beta(1) integrin to its ligands VCAM-1 and fibronectin in vitro. Treatment of B. burgdorferi-infected C3H/Hej mice with the alpha(4)beta(1), antagonist significantly ameliorated the outcome of clinical arthritis and the influx of neutrophilic granulocytes into ankle joints. Furthermore, local mRNA up-regulation of the proinflammatory mediators IL-1, IL-6, and cyclooxygenase-2 was largely abolished. Neither the synthesis of spirochete-specific Igs nor the development of a Th1-dominated immune response was altered by the treatment. Importantly, the drug also did not interfere with Ab-mediated control of spirochete load in the tissues. These findings demonstrate that the pathogenesis, but not the protective immune response, in Lyme arthritis is dependent on the alpha(4)beta(1)-mediated influx of inflammatory cells. The onset of inflammation can be successfully targeted by treatment with S18407.
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| 69. |
- Kilpeläinen, Tuomas O, et al.
(författare)
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Genetic variation near IRS1 associates with reduced adiposity and an impaired metabolic profile.
- 2011
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Ingår i: Nature genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 43:8, s. 753-60
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Tidskriftsartikel (refereegranskat)abstract
- Genome-wide association studies have identified 32 loci influencing body mass index, but this measure does not distinguish lean from fat mass. To identify adiposity loci, we meta-analyzed associations between ∼2.5 million SNPs and body fat percentage from 36,626 individuals and followed up the 14 most significant (P < 10(-6)) independent loci in 39,576 individuals. We confirmed a previously established adiposity locus in FTO (P = 3 × 10(-26)) and identified two new loci associated with body fat percentage, one near IRS1 (P = 4 × 10(-11)) and one near SPRY2 (P = 3 × 10(-8)). Both loci contain genes with potential links to adipocyte physiology. Notably, the body-fat-decreasing allele near IRS1 is associated with decreased IRS1 expression and with an impaired metabolic profile, including an increased visceral to subcutaneous fat ratio, insulin resistance, dyslipidemia, risk of diabetes and coronary artery disease and decreased adiponectin levels. Our findings provide new insights into adiposity and insulin resistance.
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| 70. |
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