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  • Barucca, G., et al. (författare)
  • Study of excited Ξ baryons with the P¯ ANDA detector
  • 2021
  • Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
  • Tidskriftsartikel (refereegranskat)abstract
    • The study of baryon excitation spectra provides insight into the inner structure of baryons. So far, most of the world-wide efforts have been directed towards N∗ and Δ spectroscopy. Nevertheless, the study of the double and triple strange baryon spectrum provides independent information to the N∗ and Δ spectra. The future antiproton experiment P¯ANDA will provide direct access to final states containing a Ξ¯ Ξ pair, for which production cross sections up to μb are expected in p¯p reactions. With a luminosity of L= 10 31 cm- 2 s- 1 in the first phase of the experiment, the expected cross sections correspond to a production rate of ∼106events/day. With a nearly 4 π detector acceptance, P¯ANDA will thus be a hyperon factory. In this study, reactions of the type p¯p → Ξ¯ +Ξ∗ - as well as p¯p → Ξ¯ ∗ +Ξ- with various decay modes are investigated. For the exclusive reconstruction of the signal events a full decay tree fit is used, resulting in reconstruction efficiencies between 3 and 5%. This allows high statistics data to be collected within a few weeks of data taking.
  • Barucca, G., et al. (författare)
  • The potential of Λ and Ξ- studies with PANDA at FAIR
  • 2021
  • Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
  • Tidskriftsartikel (refereegranskat)abstract
    • The antiproton experiment PANDA at FAIR is designed to bring hadron physics to a new level in terms of scope, precision and accuracy. In this work, its unique capability for studies of hyperons is outlined. We discuss ground-state hyperons as diagnostic tools to study non-perturbative aspects of the strong interaction, and fundamental symmetries. New simulation studies have been carried out for two benchmark hyperon-antihyperon production channels: p¯ p→ Λ¯ Λ and p¯ p→ Ξ¯ +Ξ-. The results, presented in detail in this paper, show that hyperon-antihyperon pairs from these reactions can be exclusively reconstructed with high efficiency and very low background contamination. In addition, the polarisation and spin correlations have been studied, exploiting the weak, self-analysing decay of hyperons and antihyperons. Two independent approaches to the finite efficiency have been applied and evaluated: one standard multidimensional efficiency correction approach, and one efficiency independent approach. The applicability of the latter was thoroughly evaluated for all channels, beam momenta and observables. The standard method yields good results in all cases, and shows that spin observables can be studied with high precision and accuracy already in the first phase of data taking with PANDA.
  • Bohlooly-Yeganeh, Mohammad, 1966, et al. (författare)
  • Growth hormone overexpression in the central nervous system results in hyperphagia-induced obesity associated with insulin resistance and dyslipidemia.
  • 2005
  • Ingår i: Diabetes. - : American Diabetes Association Inc.. - 0012-1797 .- 1939-327X. ; 54:1, s. 51-62
  • Tidskriftsartikel (refereegranskat)abstract
    • It is well known that peripherally administered growth hormone (GH) results in decreased body fat mass. However, GH-deficient patients increase their food intake when substituted with GH, suggesting that GH also has an appetite stimulating effect. Transgenic mice with an overexpression of bovine GH in the central nervous system (CNS) were created to investigate the role of GH in CNS. This study shows that overexpression of GH in the CNS differentiates the effect of GH on body fat mass from that on appetite. The transgenic mice were not GH-deficient but were obese and showed increased food intake as well as increased hypothalamic expression of agouti-related protein and neuropeptide Y. GH also had an acute effect on food intake following intracerebroventricular injection of C57BL/6 mice. The transgenic mice were severely hyperinsulinemic and showed a marked hyperplasia of the islets of Langerhans. In addition, the transgenic mice displayed alterations in serum lipid and lipoprotein levels and hepatic gene expression. In conclusion, GH overexpression in the CNS results in hyperphagia-induced obesity indicating a dual effect of GH with a central stimulation of appetite and a peripheral lipolytic effect.
  • 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. - 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.
  • Golubev, Pavel, et al. (författare)
  • Pion Emission in H-2,C-12,Al-27(gamma,pi+) Reactions at Threshold
  • 2008
  • Ingår i: Nuclear Physics, Section A. - : Elsevier. - 0375-9474 .- 1873-1554. ; 806:1-4, s. 216-229
  • Tidskriftsartikel (refereegranskat)abstract
    • The very first data from MAX-lab in Lund, Sweden on pion photoproduction at threshold energies are presented. The decrease of the total π+ yield in γ+12C, 27Al reactions below 200 MeV as well as the dσ/dΩ cross-section data essentially follow the predictions of an intranuclear-cascade model with an attractive potential for the pion–nucleus interaction. However, View the MathML source, cross-section data at 176 MeV show deviations which call for refinements of the model and possibly also for the inclusion of coherent pion-production mechanisms.
  • Makonyi, K., et al. (författare)
  • Evaluating vacuum phototriodes designed for the PANDA electromagnetic calorimeter
  • 2014
  • Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier. - 0167-5087. ; 763, s. 36-43
  • Tidskriftsartikel (refereegranskat)abstract
    • In this work properties of a vacuum phototriode (VPT) and preamplifier unit designed for the electromagnetic calorimeter of the PANDA experiment being built at FAIR are investigated. With the use of lead tungstate and lanthanium bromide scintillators the VPT properties are studied at low photon energies, from tens of key in the lanthanium bromide measurements and between 10 MeV and 60 MeV in the lead tungstate measurements. At these energies the noise of the VPT unit can be expected to influence its performance significantly. It is shown that the noise contribution to the measured energy resolution, under optimal conditions, is consistent with a fluctuation of (one standard deviation) approximately 200 electrons at the VPT anode. For a lead tungstate crystal this is equivalent to a noise of 1.2 MeV. For lanthanium bromide this makes it possible to use VPTs for gamma ray spectroscopy above a few hundreds of keV without noticeable effects on the energy resolution compared to measurements with a standard photomultiplier. (C) 2014 Elsevier B.V. All rights reserved.
  • Ohlson, Sten, et al. (författare)
  • Toward high-throughput drug screening on a chip-based parallell affinity separation platform
  • 2010
  • Ingår i: Journal of Separation Science. - 1615-9306 .- 1615-9314. ; 33:17-18, s. 2575-2581
  • Tidskriftsartikel (refereegranskat)abstract
    • High-throughput screening of compound libraries, including the study of fragments, has become one of the cornerstones in modern drug discovery research. During this process hits are defined that may be developed into valuable leads and eventually into possible drug candidates. In this paper, we have demonstrated that parallel zonal weak affinity chromatography in microcolumns on a chip offers a possible screening format for weakly binding ligands toward a protein target. We used albumin as a model system because this transport protein is well established as a binder (both weak and strong) for drug substances. Bovine serum albumin was immobilized on microparticulate diolsilica particles and then packed into a 24-channel cartridge, which served as the separation platform. Analysis of the obtained chromatograms yielded information about affinity even in the millimolar range. Employing this approach, thousands of substances can be screened in just a day. We feel confident that zonal affinity chromatography will provide a useful technology in the future for performing high-throughput screening.
  • Samnegård, Björn, et al. (författare)
  • C-peptide and captopril are equally effective in lowering glomerular hyperfiltration in diabetic rats.
  • 2004
  • Ingår i: Nephrol Dial Transplant. - 0931-0509. ; 19:6, s. 1385-91
  • Tidskriftsartikel (övrigt vetenskapligt)abstract
    • 150042582004051920040921200611150931-05091962004JunNephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal AssociationNephrol. Dial. Transplant.C-peptide and captopril are equally effective in lowering glomerular hyperfiltration in diabetic rats.1385-91BACKGROUND: C-peptide has been shown to reduce glomerular hyperfiltration, glomerular hypertrophy and urinary albumin excretion in type 1 diabetes, but its effect has not been compared with that of an angiotensin-converting enzyme inhibitor (ACEI) in the early stage of renal involvement in diabetes. METHODS: Glomerular filtration rate (GFR) was measured in terms of inulin clearance and renal blood flow, using ultrasound technique, in four groups of streptozotocin-induced diabetic rats before and after a 60 min infusion of C-peptide (D-Cp), captopril (D-ACEI), C-peptide and captopril (D-Cp-ACEI) or placebo (D-placebo). In addition, a non-diabetic control group was studied before and after captopril infusion (C-ACEI). RESULTS: GFR was 37-51% higher in the diabetic groups than in the control animals. GFR decreased after treatment in the D-Cp, D-ACEI and D-Cp-ACEI groups, but did not change in the D-placebo group. Blood flow increased by 26-32% in the three groups receiving captopril and by 5% in the diabetic groups treated with C-peptide alone or placebo. The increase in blood flow in the three ACEI-treated groups was significantly greater than in the D-placebo group. Filtration fraction fell significantly in all groups, but only in the combined D-Cp-ACEI group did it fall significantly more than in the D-placebo group. CONCLUSIONS: C-peptide and captopril lower diabetes-induced glomerular hyperfiltration to a similar extent, but the influence of captopril on blood flow is greater than that of C-peptide, suggesting different mechanisms of action. No statistically significant additive effects of C-peptide and captopril were shown in this acute infusion study.Department of Nephrology, Danderyd Hospital, SE-182 88 Stockholm, Sweden. bjorn.samnegard@medks.ki.seSamnegårdBjörnBJacobsonStefan HSHJohanssonBo-LennartBLEkbergKarinKIsakssonBrittaBWahrenJohnJSjöquistMatsMengComparative StudyJournal Article20040305EnglandNephrol Dial Transplant87064020Angiotensin-Converting Enzyme Inhibitors0C-Peptide62571-86-2CaptoprilIMAngiotensin-Converting Enzyme InhibitorspharmacologyAnimalsC-PeptidepharmacologyCaptoprilpharmacologyDiabetes Mellitus, ExperimentalphysiopathologyGlomerular Filtration Ratedrug effectsKidney Glomerulusdrug effectsphysiopathologyMaleRatsRats, Sprague-DawleyRegional Blood Flowdrug effects200439502004924502004Mar5ppublish1500425810.1093/ndt/gfh163gfh163
  • Samuelsson, Annika, 1964-, et al. (författare)
  • Changes in the aerobic faecal flora of patients treated with antibiotics for acute intra-abdominal infection
  • 2012
  • Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa Healthcare. - 0036-5548 .- 1651-1980. ; 44:11, s. 820-827
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: An open observational study was performed to investigate changes in the rectal flora and antibiotic susceptibility among faecal bacteria in patients treated with antibiotics for acute intra-abdominal infection. Methods: One hundred and forty patients with acute intra-abdominal infection requiring antibiotic treatment and hospitalization were included. Eight surgical units from the southern part of Sweden participated, between January 2006 and November 2007. Antibiotic treatments were according to local guidelines. Rectal swabs were obtained on admission (sample 1) and 2-14 days after the end of antibiotic treatment (sample 2). Aerobic bacteria and yeasts were analysed. The material was divided into 2 groups: 1 group with Enterobacteriaceae and 1 group with non-fermentative Gram-negative bacteria. The susceptibility to antibiotics in each group was compared between samples 1 and 2. Results: The main finding of this study on patients with severe intra-abdominal infections was a shift in the aerobic faecal flora following antibiotic treatment, from Escherichia coli to other more resistant Enterobacteriaceae, Enterococcus faecium, and yeasts. The susceptibility to cephalosporins and piperacillin-tazobactam decreased in Enterobacteriaceae. Conclusions: Following antibiotic treatment, a shift in the aerobic rectal flora to species with intrinsic antibiotic resistance was observed. This indicates that the emergence of resistance is not due to new mutations, but rather to selection of more resistant species. This should be taken into account when designing treatments for secondary intra-abdominal infections.
  • 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. - 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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