| 1. |
- Singh, B. P., et al.
(författare)
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Experimental access to Transition Distribution Amplitudes with the PANDA experiment at FAIR
- 2015
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Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 51:8
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Tidskriftsartikel (refereegranskat)abstract
- Baryon-to-meson Transition Distribution Amplitudes (TDAs) encoding valuable new information on hadron structure appear as building blocks in the collinear factorized description for several types of hard exclusive reactions. In this paper, we address the possibility of accessing nucleon-to-pion (pi N) TDAs from (p) over barp -> e(+)e(-)pi(0) reaction with the future PANDA detector at the FAIR facility. At high center-of-mass energy and high invariant mass squared of the lepton pair q(2), the amplitude of the signal channel (p) over barp -> e(+)e(-)pi(0) admits a QCD factorized description in terms of pi N TDAs and nucleon Distribution Amplitudes (DAs) in the forward aid backward kinematic regimes. Assuming the validity of this factorized description, we perform feasibility studies for measuring (p) over barp -> e(+)e(-)pi(0) with the PANDA detector. Detailed simulations on signal reconstruction efficiency as well as on rejection of the most severe background channel, i.e. (p) over barp -> pi(+)pi(-)pi(0) were performed for the center-of-mass energy squared s = 5 GeV2 and s = 10 GeV2, in the kinematic regions 3.0 < q(2) < 4.3 GeV2 and 5 < q(2) < 9 GeV2, respectively, with a neutral pion scattered in the forward or backward cone vertical bar cos theta(pi 0)vertical bar > 0.5 in the proton-antiproton center-of-mass frame. Results of the simulation show that the particle identification capabilities of the PANDA detector will allow to achieve a background rejection factor of 5 . 10(7) (1 . 10(7)) at low (high) q(2) for s = 5 GeV2, and of 1 . 10(8) (6 . 10(6)) at low (high) q(2) for s = 10 GeV2, while keeping the signal reconstruction efficiency at around 40%. At both energies, a clean lepton signal can be reconstructed with the expected statistics corresponding to 2 of integrated luminosity. The cross sections obtained from the simulations are used to show that a test of QCD collinear factorization can be done at the lowest order by measuring scaling laws and angular distributions. The future measurement of the signal channel cross section with PANDA will provide a new test of the perturbative QCD description of a novel class of hard exclusive reactions and will open the possibility of experimentally accessing pi N TDAs.
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| 3. |
- Bergquist, A, et al.
(författare)
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Epidemiology of cholangiocarcinoma
- 2015
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Ingår i: Best practice & research. Clinical gastroenterology. - : Elsevier BV. - 1532-1916 .- 1521-6918. ; 29:2, s. 221-232
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Tidskriftsartikel (refereegranskat)
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| 6. |
- Larsson, Petter, et al.
(författare)
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Consequences of past climate change and recent human persecution on mitogenomic diversity in the arctic fox
- 2019
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Ingår i: Philosophical Transactions of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 374:1788
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Tidskriftsartikel (refereegranskat)abstract
- Ancient DNA provides a powerful means to investigate the timing, rate and extent of population declines caused by extrinsic factors, such as past climate change and human activities. One species probably affected by both these factors is the arctic fox, which had a large distribution during the last glaciation that subsequently contracted at the start of the Holocene. More recently, the arctic fox population in Scandinavia went through a demographic bottleneck owing to human persecution. To investigate the consequences of these processes, we generated mitogenome sequences from a temporal dataset comprising Pleistocene, historical and modern arctic fox samples. We found no evidence that Pleistocene populations in mid-latitude Europe or Russia contributed to the present-day gene pool of the Scandinavian population, suggesting that postglacial climate warming led to local population extinctions. Furthermore, during the twentieth-century bottleneck in Scandinavia, at least half of the mitogenome haplotypes were lost, consistent with a 20-fold reduction in female effective population size. In conclusion, these results suggest that the arctic fox in mainland Western Europe has lost genetic diversity as a result of both past climate change and human persecution. Consequently, it might be particularly vulnerable to the future challenges posed by climate change. This article is part of a discussion meeting issue 'The past is a foreign country: how much can the fossil record actually inform conservation?'
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| 7. |
- Nordenvall, C., et al.
(författare)
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Colectomy prior to diagnosis of primary sclerosing cholangitis is associated with improved prognosis in a nationwide cohort study of 2594 PSC-IBD patients
- 2018
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Ingår i: Alimentary Pharmacology and Therapeutics. - : WILEY. - 0269-2813 .- 1365-2036. ; 47:2, s. 238-245
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Tidskriftsartikel (refereegranskat)abstract
- Background: Despite the close relationship between primary sclerosing cholangitis (PSC) and inflammatory bowel disease (IBD), the association between colectomy and the prognosis of PSC remains controversial. Aim: To explore whether colectomy prior to PSC-diagnosis is associated with transplant-free survival. Methods; A nationwide cohort study in Sweden including all patients aged 18 to 69 years in whom both PSC and IBD was diagnosed between 1987 and 2014 was undertaken. Each patient was followed from date of both PSC and IBD diagnoses until liver transplantation or death, or 31 December 2014. Patients with colon in situ, and colectomy prior to PSC-diagnosis were compared. Survival analyses were performed using the Kaplan-Meier method and multivariable Cox regression models. Results: Of the 2594 PSC-IBD patients, 205 patients were treated with colectomy before PSC-diagnosis. During follow-up, liver transplantations were performed in 327 patients and 509 died. The risk of liver transplantation or death was lower in patients treated with colectomy prior to PSC-diagnosis (HR 0.71, 95% CI 0.53-0.95) than in patients with colon in situ. Male gender, longer time between IBD and PSC-diagnosis and older age were all associated with an increased risk of liver transplantation or death. Colectomy after PSC-diagnosis was however not associated with an increased risk of liver transplantation or death during long-term follow-up. Conclusions: In PSC-IBD patients, colectomy prior to PSC-diagnosis is associated with a decreased risk of liver transplantation or death.
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