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Träfflista för sökning "WFRF:(Walther T) ;lar1:(lu)"

Sökning: WFRF:(Walther T) > Lunds universitet

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2.
  • Singh, B. P., et al. (författare)
  • Experimental access to Transition Distribution Amplitudes with the PANDA experiment at FAIR
  • 2015
  • Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 51:8
  • 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.
  • Erni, W., et al. (författare)
  • Technical design report for the PANDA (AntiProton Annihilations at Darmstadt) Straw Tube Tracker
  • 2013
  • Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 49:2
  • Tidskriftsartikel (refereegranskat)abstract
    • This document describes the technical layout and the expected performance of the Straw Tube Tracker (STT), the main tracking detector of the PANDA target spectrometer. The STT encloses a Micro-Vertex-Detector (MVD) for the inner tracking and is followed in beam direction by a set of GEM stations. The tasks of the STT are the measurement of the particle momentum from the reconstructed trajectory and the measurement of the specific energy loss for a particle identification. Dedicated simulations with full analysis studies of certain proton-antiproton reactions, identified as being benchmark tests for the whole PANDA scientific program, have been performed to test the STT layout and performance. The results are presented, and the time lines to construct the STT are described.
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5.
  • Aberg, T, et al. (författare)
  • Cerebral function monitoring in rats with a critical hepatic injury treated with pneumatic antishock garment and infusion
  • 1989
  • Ingår i: Journal of Trauma. - 0022-5282. ; 29:2, s. 168-174
  • Tidskriftsartikel (refereegranskat)abstract
    • Twenty-nine rats were subjected to a severe standardized hepatic injury and divided into four groups. In addition to controls, the animals were treated with PASG inflated to 40 mm Hg, PASG and infusion of Ringer's acetate, or PASG and infusion of Ringer's acetate and Dextran 70 in combination. The aim of the infusion therapy was to stabilize the mean aortic blood pressure at 60 mm Hg. PASG significantly prolonged the survival time and the time during which a sensory evoked response could be observed. The PASG also prolonged the time before the EEG amplitude began to decrease or a burst-suppression pattern appeared in the EEG. Intravenous infusion of Ringer's acetate did not prolong these times compared to when PASG was used alone; when Dextran 70 was added to the infusion therapy these times were reduced. Changes in the EEG were recorded at a mean aortic pressure of 60 mm Hg when infusions were given, whereas the aortic pressure had to fall to 40 mm Hg before any changes could be observed when no infusions were used.
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6.
  • Alef, S., et al. (författare)
  • The BGOOD experimental setup at ELSA
  • 2020
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 56:4
  • Tidskriftsartikel (refereegranskat)abstract
    • The BGOOD experiment at the ELSA facility in Bonn has been commissioned within the framework of an international collaboration. The experiment pursues a systematic investigation of non-strange and strange meson photoproduction, in particular t-channel processes at low momentum transfer. The setup uniquely combines a central almost 4 π acceptance BGO crystal calorimeter with a large aperture forward magnetic spectrometer providing excellent detection of both neutral and charged particles, complementary to other setups such as Crystal Barrel, Crystal Ball, LEPS and CLAS.
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7.
  • Goldner, Ph., et al. (författare)
  • Long coherence lifetime and electromagnetically induced transparency in a highly-spin-concentrated solid
  • 2009
  • Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 79:3
  • Tidskriftsartikel (refereegranskat)abstract
    • We have studied a rare-earth-doped crystal, Pr3+:La-2(WO4)(3), which exhibits a high magnetic-moment density. Although the latter favors rare-earth dephasing, a nuclear-spin coherence lifetime of 250 mu s has been observed, as well as electromagnetically induced transparency (EIT). This suggests that a broad range of materials could be considered for quantum information applications such as quantum memories for light, where solids are especially attractive. Absorption and dispersion curves are independently in very good agreement with EIT theory. Fano-like profiles have also been observed.
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8.
  • Johansson, J, et al. (författare)
  • Active or passive chest drainage after oesophagectomy in 101 patients : a prospective randomized study
  • 1998
  • Ingår i: British Journal of Surgery. - 0007-1323. ; 85:8, s. 6-1143
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: This study evaluates the efficiency and safety of two methods of chest drainage after uncomplicated oesophagectomy.METHODS: A prospective randomized study between active suction drainage and passive chest drainage was carried out in 101 patients who underwent gastric pull-up oesophagectomy.RESULTS: No difference in the prevalence of pneumothorax during treatment was noted between the active (nine of 55) and the passive (four of 46) drainage groups (P=0.20). Nor was there any difference in the size (P=0.46) and duration (P=0.53) of the pneumothorax. There was no significant difference in right (P=0.84) and left (P=0.61) basal atelectases and the amounts of right (P=0.10) and left (P=0.24) pleural effusions. There were significantly more basal atelectases (P < 0.001) and pleural effusions (P<0.001) in the non-operated left side compared with the operated right side. Postoperative hospital stay was the same in both groups (median 13 days; P=0.86). The hospital mortality rate was two of 101, and was not affected by the type of drainage.CONCLUSION: Passive drainage did not reduce hospital stay, but was as safe and effective as the active system in draining the pleural cavity after uncomplicated oesophagectomy.
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9.
  • Johansson, J, et al. (författare)
  • Adenocarcinoma in the distal esophagus with and without Barrett esophagus. Differences in symptoms and survival rates
  • 1996
  • Ingår i: Archives of Surgery. - : American Medical Association (AMA). - 0004-0010. ; 131:7, s. 13-708
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE: To evaluate differences in clinical appearance and survival rates in patients operated on for adenocarcinoma in the distal esophagus with and without Barrett epithelium.DESIGN: Prospective clinical study.SETTING: University hospital, Sweden.PATIENTS: Fifty-four patients with adenocarcinoma in the distal esophagus with (n = 17) or without (n = 37) Barrett epithelium.INTERVENTION: Esophagectomy or total gastrectomy.MAIN OUTCOME MEASURES: Preoperative symptoms, endoscopic results, and histological findings; postoperative morbidity, mortality, and survival rates.RESULTS: The main indication for the endoscopic examination that revealed tumor in the group with Barrett esophagus was reflex-related symptoms in 6 patients (routine Barrett examination, n = 4; symptoms of reflux, n = 2), symptoms related to upper gastrointestinal tract bleeding in 6, and malignant symptoms in 5 (dysphagia, n = 4; weight loss, n = 1). In contrast, most patients in the cardia cancer group were admitted because of malignant symptoms (dysphagia, n = 26; epigastric pain, n = 9; and anemia, n = 2). Ten of 17 patients in the Barrett esophagus cancer group had tumors limited to the mucosa and submucosa only. In 1 patient the tumor grew into the muscular layer but not through it. In the remaining 6 patients the tumor did grow through the muscular layer and lymph node metastases were found. Wall penetration was found in 30 patients and metastases to lymph nodes in 29 patients in the cardia cancer group. The hospital mortality rate was 0 of 17 patients in the Barrett cancer group and 2 of 37 patients in the cardia cancer group. In the patients operated on for adenocarcinoma in the distal esophagus, a better long-term survival rate was seen in those with Barrett epithelium (50%) than in those without this metaplasia (10%) (log rank P = .005; X2 = 7.80).CONCLUSIONS: Concomitant Barrett epithelium improved the prognosis for patients with adenocarcinoma in the distal esophagus. Probably the reason for this was a higher rate of early-stage disease, because symptoms of gastroesophageal reflux and other benign disorders, not dysphagia, were most common in patients with adenocarcinoma without Barrett epithelium in the distal esophagus.
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10.
  • Zamora, Juan Carlos, et al. (författare)
  • Considerations and consequences of allowing DNA sequence data as types of fungal taxa
  • 2018
  • Ingår i: IMA Fungus. - : INT MYCOLOGICAL ASSOC. - 2210-6340 .- 2210-6359. ; 9:1, s. 167-185
  • 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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