| 1. |
- Albrecht, Malte, et al.
(author)
-
The Forward Endcap of the Electromagnetic Calorimeter for the PANDA Detector at FAIR
- 2015
-
In: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 587:1
-
Journal article (peer-reviewed)abstract
- The versatile 4π-detector PANDA will be built at the Facility for Antiproton and Ion Research (FAIR), an accelerator complex, currently under construction near Darmstadt, Germany. A cooled antiproton beam in a momentum range of 1.5 – 15GeV/c will be provided by the High Energy Storage Ring (HESR). All measurements at PANDA rely on an excellent performance of the detector with respect to tracking, particle identification and energy measurement. The electromagnetic calorimeter (EMC) of the PANDA detector will be equipped with 15744 PbWO(4) crystals (PWO-II), which will be operated at a temperature of – 25° C in order to increase the light output. The design of the forward endcap of the EMC has been finalized. The crystals will be read out with Large Area Avalanche Photo Diodes (LAAPDs) in the outer regions and with Vacuum Photo Tetrodes (VPTTs) in the innermost part. Production of photosensor units utilizing charge integrating preamplifiers has begun. A prototype comprised of 216 PbWO4 crystals has been built and tested at various accelerators (CERN SPS, ELSA/Bonn, MAMI/Mainz), where the crystals have been exposed to electron and photon beams of 25MeV up to 15GeV. The results of these test measurements regarding the energy and position resolution are presented.
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| 2. |
- Atomassa, Ermias, et al.
(author)
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Feasibility studies for nucleon structure measurements with PANDA
- 2014
-
In: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 81
-
Journal article (peer-reviewed)abstract
- The study of nucleon structure is one of the main physics goals of PANDA to be built at the FAIR accelerator complex. The excellent particle identification performance of the PANDA detector will enable measurements of exclusive channels p̄ p -> e^+e^- and p̄ p -> pi^0 J/psi -> pi^0e^+e^- to extract the electromagnetic form factors of protons and pi-nucleon Transition Distribution Amplitudes (pi-N TDAs). After a brief description of the PANDA apparatus and a method to handle momentum resolution degradation due to Bremsstrahlung, the physics of pi-N TDAs is discussed. An estimate for the expected signal to background ratio for p̄ p -> pi^0 J/psi -> pi^0e^+e^- that takes into account the main background source is given.
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| 3. |
- Bargholtz, Chr., et al.
(author)
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Measurement of the eta -> pi(+)pi(-)e(+)e(-) decay branching ratio
- 2007
-
In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 644:5-6, s. 299-303
-
Journal article (peer-reviewed)abstract
- The reaction pd -> He-3 eta at threshold was used to provide a clean source of eta mesons for decay studies with the WASA detector at CELSIUS. The branching ratio of the decay eta -> pi(+)pi(-)e(+)e(-) is measured to be (4.3 +/- 1.3 +/- 0.4) x 10(-4).
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| 4. |
- Bargholtz, Chr., et al.
(author)
-
The WASA detector facility at CELSIUS
- 2008
-
In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 594:3, s. 339-350
-
Journal article (peer-reviewed)abstract
- The WASA 4 pi multidetector system, aimed at investigating light meson production in light ion collisions and eta meson rare decays at the CELSIUS storage ring in Uppsala is presented. A unique feature of the system is the use of hydrogen pellets as internal targets for the first time. A detailed description of the design, together with the anticipated and achieved performance parameters are given. (C) 2008 Elsevier B.V. All rights reserved.
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| 5. |
- Bashkanov, M., et al.
(author)
-
Double-Pionic Fusion of Nuclear Systems and the "ABC" Effect : Approaching a Puzzle by Exclusive and Kinematically Complete Measurements
- 2009
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:5, s. 052301-
-
Journal article (peer-reviewed)abstract
- The ABC effect-a puzzling low-mass enhancement in the pi pi invariant mass spectrum, first observed by Abashian, Booth, and Crowe-is well known from inclusive measurements of two-pion production in nuclear fusion reactions. Here we report on the first exclusive and kinematically complete measurements of the most basic double-pionic fusion reaction pn -> d pi(0)pi(0) at beam energies of 1.03 and 1.35 GeV. The measurements, which have been carried out at CELSIUS-WASA, reveal the ABC effect to be a (pi pi)(I=L=0) channel phenomenon associated with both a resonancelike energy dependence in the integral cross section and the formation of a Delta Delta system in the intermediate state. A corresponding simple s-channel resonance ansatz provides a surprisingly good description of the data.
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| 6. |
- Bashkanov, M., et al.
(author)
-
Measurement of the slope parameter for the η → 3π0 decay in the pp → ppη reaction
- 2007
-
In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 76:4, s. 048201-
-
Journal article (peer-reviewed)abstract
- The CELSIUS-WASA setup is used to measure the 3π0 decay of η mesons produced in pp interactions with beam kinetic energies of 1.36 and 1.45 GeV. The efficiency-corrected Dalitz plot and density distributions for this decay are shown, together with a fit of the quadratic slope parameter α yielding α = −0.026 ± 0.010(stat) ± 0.010(syst). This value is compared to recent experimental results and theoretical predictions.
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| 7. |
- Berlowski, M., et al.
(author)
-
Measurement of eta meson decays into lepton-antilepton pairs
- 2008
-
In: Physical Review D. Particles and fields. - : American Physical Society. - 0556-2821 .- 1089-4918. ; 77:3, s. 032004-
-
Journal article (peer-reviewed)abstract
- A search for rare lepton decays of the eta meson was performed using the WASA detector at CELSIUS. Two candidates for double Dalitz decay eta -> e(+)e(-)e(+)e(-) events are reported with a background of 1.3 +/- 0.2 events. This allows to set an upper limit to the branching ratio of 9.7x10(-5) (90% CL). The branching ratio for the decay eta -> e(+)e(-)gamma is determined to (7.8 +/- 0.5(stat)+/- 0.8(syst))x10(-3) in agreement with world average value. An upper limit (90% CL) for the branching ratio for the eta -> e(+)e(-) decay is 2.7x10(-5) and a limit for the sum of the eta ->mu(+)mu(-)mu(+)mu(-) and eta ->pi(+)pi(-)mu(+)mu(-) decays is 3.6x10(-4).
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| 8. |
- Biernat, Jacek, et al.
(author)
-
Feasibility studies for the Forward Spectrometer
- 2015
-
In: Journal of Physics, Conference Series. - 1742-6588 .- 1742-6596. ; 599:1
-
Journal article (peer-reviewed)abstract
- The Forward Spectrometer designed for the P̄ANDA detector will consist of many different detector systems allowing for precise track reconstruction and particle identification. Feasibility studies for Forward Spectrometer done by means of specific reactions will be presented. In the first part of the paper, results of simulations focussing on rate estimates of the tracking stations based on straw tubes will be presented. Next, the importance of the Forward Tracker will be demonstrated through the reconstruction of the ψ(4040) → DD̄ decay. Finally, results from the analysis of the experimental data collected with a straw tube prototype designed and constructed at the Research Center in Juelich will be discussed.
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| 9. |
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| 10. |
- Boca, Gianluigi, et al.
(author)
-
The experiment PANDA: physics with antiprotons at FAIR
- 2015
-
In: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 95
-
Journal article (peer-reviewed)abstract
- PANDA is an experiment that will run at the future facility FAIR, Darmstadt, Germany. A high intensity and cooled antiproton beam will collide on a fixed hydrogen or nuclear target covering center-of-mass energies between 2.2 and 5.5 GeV. PANDA addresses various physics aspects from the low energy non-perturbative region towards the perturbative regime of QCD. With the impressive theoretical developments in this field, e.g. lattice QCD, the predictions are becoming more accurate in the course of time. The data harvest with PANDA will, therefore, be an ideal test bench with the aim to provide a deeper understanding of hadronic phenomena such as confinement and the generation of hadron masses. A variety of physics topics will be covered with PANDA, for example: the formation or production of exotic non-qqbar charm meson states connected to the recently observed XYZ spectrum; the study of gluon-rich matter, such as glueballs and hybrids; the spectroscopy of the excited states of strange and charm baryons, their production cross section and their spin correlations; the behaviour of hadrons in nuclear matter; the hypernuclear physics; the electromagnetic proton form factors in the timelike region.
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| 11. |
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| 12. |
- Bock, David, 1976, et al.
(author)
-
Explorative analysis of spatial aspects on the Swedish influenza data
- 2007
-
Reports (other academic/artistic)abstract
- The spatial aspects on the Swedish influenza data are analyzed. During the influenza period, reports on laboratory diagnosed cases and influenza-like-illness are obtained from viral and microbiological laboratories and from sentinel physicians, respectively, in different regions of Sweden. Information about the spatio-temporal patterns might give insight in the way the influenza spreads over Sweden. It might also be used in automated surveillance systems for outbreak and peak detection of the influenza. We describe the regional patterns in Swedish influenza data in different ways. Several natural hypotheses about geographical patterns are examined but can not be verified as consistent over the years. However, we find that, for a group of large cities, the outbreak of the influenza occurs at least four weeks earlier than for the rest of Sweden. The possibilities to utilize this in surveillance systems are briefly discussed.
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| 13. |
- Bock, David, 1976, et al.
(author)
-
Exploratory analysis of spatial aspects on the Swedish influenza
- 2006
-
Reports (other academic/artistic)abstract
- The spatial aspects on the Swedish influenza data are analyzed. During the influenza period, reports on laboratory diagnosed cases and influenza-like-illness are obtained from viral and microbiological laboratories and from sentinel physicians, respectively, in different regions of Sweden. Information about the spatio-temporal patterns might give insight in the way the influenza spreads over Sweden. It might also be used in automated surveillance systems for outbreak and peak detection of the influenza. We describe the regional patterns in Swedish influenza data in different ways. Several natural hypotheses about geographical patterns are examined but can not be verified as consistent over the years. However, we find that, for a group of large cities, the outbreak of the influenza occurs at least four weeks earlier than for the rest of Sweden. The possibilities to utilize this in surveillance systems are briefly discussed.
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| 14. |
- Braniste, Viorica, et al.
(author)
-
The gut microbiota influences blood-brain barrier permeability in mice
- 2014
-
In: Science Translational Medicine. - : American Association for the Advancement of Science. - 1946-6234 .- 1946-6242. ; 6:263, s. 263ra158-
-
Journal article (peer-reviewed)abstract
- Pivotal to brain development and function is an intact blood-brain barrier (BBB), which acts as a gatekeeper to control the passage and exchange of molecules and nutrients between the circulatory system and the brain parenchyma. The BBB also ensures homeostasis of the central nervous system (CNS). We report that germ-free mice, beginning with intrauterine life, displayed increased BBB permeability compared to pathogen-free mice with a normal gut flora. The increased BBB permeability was maintained in germ-free mice after birth and during adulthood and was associated with reduced expression of the tight junction proteins occludin and claudin-5, which are known to regulate barrier function in endothelial tissues. Exposure of germ-free adult mice to a pathogen-free gut microbiota decreased BBB permeability and up-regulated the expression of tight junction proteins. Our results suggest that gut microbiota-BBB communication is initiated during gestation and propagated throughout life.
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| 15. |
- Bremer, Daniel, et al.
(author)
-
Performance of prototypes for the PANDA barrel EMC
- 2015
-
In: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 587:1
-
Journal article (peer-reviewed)abstract
- The PANDA experiment will be part of the future Facility for Antiproton and Ion Research (FAIR) and aims for the study of strong interaction within the charm sector via antiproton proton collisions up to antiproton momenta of 15 GeV/c. Reflecting the variety of the physics program the PANDA detector is designed as a multi-purpose detector able to perform tracking, calorimetry and particle identification with nearly complete coverage of the solid angle. The Electromagnetic Calorimeter (EMC) contained inside its Target Spectrometer is based on cooled PbWO(4) scintillator crystals. In order to ensure an excellent performance throughout the large dynamic range of photon/electron energies ranging from a few MeV up to 15 GeV an extensive prototyping phase is mandatory. This contribution describes the measured response of the EMC barrel part prototype PROTO60 at the largest design energy to secondary beams provided by the SPS at CERN. In addition to PROTO60 a tracking station was deployed, providing precise position information of the 15 GeV/c positrons. For calibration purposes a 150 GeV/c muon beam and cosmic radiation, in combination with estimations from GEANT4 simulations were used. The obtained performance concerning energy, position and time information is presented.
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| 16. |
- Brunnström, Kjell, 1960-, et al.
(author)
-
Quality of Experience for a Virtual Reality simulator
- 2018
-
In: Human Vision and Electronic Imaging 2018. - : The Society for Imaging Science and Technology.
-
Conference paper (peer-reviewed)abstract
- In this study, we investigate a VR simulator of a forestry crane used for loading logs onto a truck, mainly looking at Quality of Experience (QoE) aspects that may be relevant for task completion, but also whether there are any discomfort related symptoms experienced during task execution. The QoE test has been designed to capture both the general subjective experience of using the simulator and to study task completion rate. Moreover, a specific focus has been to study the effects of latency on the subjective experience, with regards both to delays in the crane control interface as well as lag in the visual scene rendering in the head mounted display (HMD). Two larger formal subjective studies have been performed: one with the VR-system as it is and one where we have added controlled delay to the display update and to the joystick signals. The baseline study shows that most people are more or less happy with the VR-system and that it does not have strong effects on any symptoms as listed in the Simulator Sickness Questionnaire (SSQ). In the delay study we found significant effects on Comfort Quality and Immersion Quality for higher Display delay (30 ms), but very small impact of joystick delay. Furthermore, the Display delay had strong influence on the symptoms in the SSQ, and causing test subjects to decide not to continue with the complete experiments. We found that this was especially connected to the longer added Display delays (≥ 20 ms).
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| 17. |
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| 18. |
- Carlström, Caroline, et al.
(author)
-
Genetic Associations of In-line Recorded Milkability Traits and Udder Conformation with Udder Health
- 2016
-
In: Acta Agriculturae Scandinavica, Section A - Animal Science. - : Informa UK Limited. - 0906-4702 .- 1651-1972. ; 66, s. 84-91
-
Journal article (peer-reviewed)abstract
- Milkability and udder conformation traits of Swedish Holstein (SH) and Swedish Red (SR) cows from 93 herds with automatic milking systems or conventional milking parlors were used to study genetic relationships to lactation average somatic cell score (LSCS) and incidence of clinical mastitis (CM). Estimated genetic correlations between measures of milking speed (average flow rate, milking time and box time) and LSCS ranged between 0.29 and 0.57 and showed that high milking speed is associated with increasing LSCS. Regressions indicated a curvilinear relationship. Genetic correlations between milking speed and CM showed similar values as for LSCS in SH cows, but were inconsistent in SR cows. Shallow udder and strong fore udder attachment were consistently correlated with good udder health. The unfavorable relationships between milking speed and udder health traits should be considered together with a few udder conformation traits when selecting for better milkability.
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| 19. |
- Carlström, Caroline, et al.
(author)
-
Genetic associations of teat cup attachment failures, incomplete milkings, and handling time in automatic milking systems with milkability, temperament, and udder conformation
- 2016
-
In: Acta Agriculturae Scandinavica, Section A - Animal Science. - : Informa UK Limited. - 0906-4702 .- 1651-1972. ; 66, s. 75-83
-
Journal article (peer-reviewed)abstract
- Automatic milking systems (AMS) allow recording of alternative milkability measures. Our objectives were to estimate genetic parameters for teat cup attachment failures (AtF), incomplete milkings (IM), and handling time (HT), and their genetic correlations with box time (BT), udder traits and temperament. Teat coordinates were to measure udder conformation and teat placement. Genetic correlations were estimated between these traits and linear classification traits. Data on Swedish Holstein and Swedish Red cows in 19 AMS herds and 74 herds with conventional milking parlors were analyzed. HT and IM had low heritabilities, but that of AtF was 0.21-0.31. Genetic correlations between AtF and temperament were 0.44-0.71 (calm cows having low AtF). Short BT was weakly genetically associated with shallow udders with short and thin teats. High genetic correlations (0.91-0.98) were found between teat coordinate traits and linear classification traits. Thus, AMS records can be effectively used to select for improved milkability and temperament.
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| 20. |
- Christensson, Marta, et al.
(author)
-
Serum sFAS levels are elevated in ANCA-positive vasculitis compared with other autoimmune diseases
- 2002
-
In: Journal of Clinical Immunology. - 0271-9142 .- 1573-2592. ; 22:4, s. 220-227
-
Journal article (peer-reviewed)abstract
- The role of the Fas/FasL system in ANCA-associated vasculitis is unclear. We therefore assessed levels of soluble Fas (sFas) in sera and Fas expression on mononuclear cells from patients with ANCA-positive vasculitis and compared the results with those found in other rheumatic diseases. Serum levels of sFas were determined by ELISA. The ANCA-positive vasculitis patients studied included 29 at onset, 17 in first remission while on therapy, and 12 in quiescence. For comparison, 10 patients with Sjogren’s syndrome (SS), 14 patients with systemic lupus erythematosus (SLE), 29 patients with rheumatoid arthritis (RA), 7 patients on dialysis (DP), and 26 healthy controls (HC) were studied. In addition, Fas expression in mononuclear cells was examined at the mRNA level using reverse transcriptase (RT)-PCR in 6 vasculitis patients at onset and in first remission. The expression of CD95 on the surface of leukocytes was determined by flow cytometry in 6 vasculitis patients at onset of the disease, in 6 patients in clinical remission, and in 6 HC. Expression of Fas and FasL in renal biopsy specimens was studied using immunohistochemistry. Patients with vasculitis had high sFas levels irrespective of disease phase. Both vasculitis patients and patients with RA and SLE had significantly increased sFas levels compared with healthy controls. All patient groups had sFas levels, which correlated with raised serum creatinine values. However, the sFas levels in vasculitis patients in first remission and in quiescence were increased despite a lower serum creatinine compared with onset. Some of the vasculitis patients showed an increased mRNA expression of Fas in mononuclear cells after treatment, suggesting that Fas production fluctuates with the intensity of the disease. The expression of CD95 on leukocytes was slightly decreased in vasculitis patients compared to healthy controls. No alterations of Fas and FasL expression were seen in renal biopsy specimens. These results show that ANCA-positive vasculitis patients have high sFas levels and that the levels remain elevated even in clinical remission. The findings indicate that perturbations in the Fas/Fas ligand system may play a role in the disease process in ANCA vasculitis.
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| 21. |
- Destefanis, Marco, et al.
(author)
-
Spin studies via Drell-Yan processes at PANDA
- 2014
-
In: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 73
-
Journal article (peer-reviewed)abstract
- The nucleon structure is still not completely understood. A transverse momentum dependent description of the nucleon structure is a crucial milestone for several forthcoming studies in a wide range of experimental scenarios. By means of antiproton beams, possibly polarized in a later stage of the project, with a beam momentum up to 15 GeV/c, which will be available at the future FAIR facility, the nonperturbative region of QCD is planned to be investigated. One of the main goals of the forthcoming experiments at FAIR is the study of Drell-Yan lepton pairs by means of proton-antiproton annihilations, taking also advantage of the expected high luminosity. The Drell-Yan production is a unique tool to access the spin dependent properties of the nucleon, and in particular its transverse degrees of freedom. Transverse Momentum Dependent (TMD) Parton Distribution Functions (PDFs), i.e. the Boer-Mulders function, the Sivers function, and the Transversity, could be deeply investigated by means of experimental angular asymmetries. In later stages of FAIR, single- and double-spin asymmetries could be investigated as well. The Drell-Yan physics program which could be accessed at FAIR with the PANDA experiment will be discussed in details, in the light of existing results in the field.
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| 22. |
- Dunér, Fredrik, et al.
(author)
-
Permeability, ultrastructural changes, and distribution of novel proteins in the glomerular barrier in early puromycin aminonucleoside nephrosis.
- 2010
-
In: Nephron. Experimental nephrology. - : S. Karger AG. - 1660-2129. ; 116:2
-
Journal article (peer-reviewed)abstract
- BACKGROUND/AIMS: It is still unclear what happens in the glomerulus when proteinuria starts. Using puromycin aminonucleoside nephrosis (PAN) rats, we studied early ultrastructural and permeability changes in relation to the expression of the podocyte-associated molecules nephrin, α-actinin, dendrin, and plekhh2, the last two of which were only recently discovered in podocytes. METHODS: Using immune stainings, semiquantitative measurement was performed under the electron microscope. Permeability was assessed using isolated kidney perfusion with tracers. Possible effects of ACE inhibition were tested. RESULTS: By day 2, some patchy foot process effacement, but no proteinuria, appeared. The amount of nephrin was reduced in both diseased and normal areas. The other proteins showed few changes, which were limited to diseased areas. By day 4, foot process effacement was complete and proteinuria appeared in parallel with signs of size barrier damage. Nephrin decreased further, while dendrin and plekhh2 also decreased but α-actinin remained unchanged. ACE inhibition had no significant protective effect. CONCLUSIONS: PAN glomeruli already showed significant pathology by day 4, despite relatively mild proteinuria. This was preceded by altered nephrin expression, supporting its pivotal role in podocyte morphology. The novel proteins dendrin and plekhh2 were both reduced, suggesting roles in PAN, whereas α-actinin was unchanged.
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| 23. |
- Efsing, Pål, 1965-
(author)
-
Delayed Hydride Cracking in Irradiated Zircaloy
- 1998
-
Doctoral thesis (other academic/artistic)abstract
- Under some circumstances nuclear fuel cladding tubes made from zirconium based alloys may develop long axial cracks. The formation of these cracks is mainly thought to be connected with the oxiditian and hydriding of the cladding which takes plage after the the formation of a small primary defect. One mechanism proposed to be responsible for the propagation of the axial cracks is delayed hydride cracking, DHC. DHC is a process where hydrogen diffuses upwards the tensile stress gradient tbat exisur in front of an existing crack or flaw. This cancentrates the hydrogen solved in the matrix to the area ahead of the growing crack. When ihe solubility limit is passed in front of the crack, hydrides are precipitated. The hydrides are assumed to be brittle in their behaviour at temperatums up to 300°ree;C. When a certain critical size is passed, the hydrides or hydride-package fracture in a brittle matmer if the lotal stress intensity leve1 is above a threshold value. allowing the crack to grow the distance of the hydridel hydride-package. The process then repeats itself at the new location of the crack tip. The aim of the thesis was to determine if regular BWR Zircaloy-2 cladding was susceptible to crack growth due to DHC or a mechanism similar to DHC in its axial direction. To enable testing on actual spent fuel cladding, a test tcchnique was developed and applied both to unirradiated and irradiated material. The specimen is similar to a normal centre cracked tension, CCT-, specimen. The test program has included investigations on the crack growth rates at 200" and 300°ree;C, the threshold stress intensity level, KIH below which no crack growth occurs and the intubation period bcfore cracking starts. The experimental work has focused on hydrogen tontents above 5OOppmH.In the unirradiated case the maximum crack growth was found to be in the vicinity of 6.10-7 m/s, while the irradiated case demonstrated crack growth rates close to 10-6 rn/s. The threshold stress intensity leve1 was found to be strongly dependent on the yield strength of the material. such that higher yield strength resulted in lower Km. The intubation period was found to be fairly constant, regardless of the hydrogen tontent and yield strength but dependent on the temperature at which the specitic experiment was conducted.The obtained crack growth rates indicates that the growth of long axial cracks in nuclear fuel cladding can be described by a mechanism similar to delayed hydride cracking at hydragen levels above 500 ppm lotally. Whether the mechanism of crack growth is DHC as described in the case high strength Zr-2.5 wt% Nb and low hydrogen tontents or a process similar to that can however not be verified experimentally sinte most of the evidente is indirect. The temperature dependence is consistent with an activation energy for crack growth close the tbeoretically derived value of 69.5 Idlmole for crack growth controlled by hydrogen diffusion in a stress induced potential gradient. Thus the crack growth can be described by an Arrhenius relationship in the steady state region with reference to applied K, stage II.
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| 24. |
- Efsing, Pål, 1965-, et al.
(author)
-
Delayed Hydride Cracking in Irradiated Zircaloy Cladding
- 2000. - STP1354
-
In: <em>Zirconium in the Nuclear Industry: Twelfth International Symposium</em>. - USA : ASTM International. ; , s. 340-355
-
Book chapter (peer-reviewed)abstract
- Slow stable crack growth by a mechanism identified as a form of delayed hydride cracking has been studied on irradiated Zircaloy cladding. The background to the investigation was the formation of long axial cracks in defected fuel rods. Post-irradiation examination of such fuel rods has indicated that precipitation and subsequent cracking of hydrides at the tips of the long cracks has played an important role in the crack growth process. The present investigation conducted on irradiated cladding with hydrogen concentrations above about 500 ppm has demonstrated that a hydrogen-induced crack growth process can occur in such material. In the laboratory it was necessary to subject the samples to an overtemperature cycle in order to initiate crack growth after fatigue precracking. It was also observed that an incubation time on the order of 20 h was necessary before crack growth started. The crack growth rates were strongly dependent on the applied stress intensity factor K in a narrow range above a threshold value KIH, which was about 10 MPa√m, Stage I. The growth rate then reached a plateau value when it was independent of K, Stage II. This plateau value was about 10-6 m/s at 300°C and about 2 × 10-7 m/s at 200°C. This temperature dependence is consistent with a mechanism based on stress-induced diffusion of hydrogen at the stress concentration of the crack tip. Metallographic and fractographic observations suggest that the details of the mechanism can be best described as a localized reduction of fracture toughness due to reorientation of hydrides so that they become perpendicular to the applied stress in the region of the crack tip. This is somewhat in contrast to previous DHC mechanisms in which longer-range diffusion of hydrogen to one large hydride at the crack tip is usually modeled. The difference is that in the present case the hydride content is higher and therefore more hydrides are present.
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| 25. |
- Efsing, Pål, 1965-, et al.
(author)
-
The influence of temperature and yield strength on delayed hydride cracking in hydrided Zircaloy-2
- 1996
-
In: Zirconium in the Nuclear Industry: Eleventh International Symposium. - West Conshohocken : ASTM International. - 9780803153431 ; , s. 394-403
-
Book chapter (peer-reviewed)abstract
- To determine if delayed hydride cracking (DHC) can be the cause of the long axial cracks occasionally found in BWR fuel cladding, a systematic study of DHC in Zircaloy cladding has begun. In the initial stage of the project, a test technique was developed and applied to unirradiated samples of Zircaloy. The present study includes an investigation of the influence of the yield strength and temperature on the crack growth rate and the threshold stress intensity that must be exceeded before cracking begins.Recrystallized (RXA) Zircaloy-2 has been compared to stress relief annealed (SRA) Zircaloy-2 with similar texture and composition. The results show that the crack propagation rate increases with increasing yield strength at similar stress intensity levels by as much as a decade when the yield strength is tripled. The maximum crack propagation rate measured in this study is ∼6 × 10-7 m/s. The threshold stress intensity, KIH, was found to decrease with increasing yield stress. The measured threshold values are in the range of 13.5 to 7.5 MPa. These figures are close to theoretically derived values using a critical fracture stress criterion of the hydrides as the limiting factor. The incubation period before cracking begins is found to be longer at 200°C than it is at 300°C.
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| 26. |
- Enghag, Per, et al.
(author)
-
An investigation into the forces and friction in wire drawing
- 2001
-
In: Wire Industry. - 0043-6011. ; 68:809, s. 272-277
-
Journal article (peer-reviewed)abstract
- The drawing machine equipped with load cells, is demostrated to measure drawing forces and calculate friction coefficients. The measurement is reported using the drawing of one wire with one lubricant but with different reductions and die geometries. The planned utilisation of the drawing machine is helpful in the investigation of unknown parameters in the wire drawing process. The machine is used for the study of surface condition of mechanically scaled wires, lubricants and carriers of different wire types and the pressure and rotating dies.
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| 27. |
- Enoksson, Staffan, et al.
(author)
-
Marked Re-Utilization of Free Fatty Acids During Activated Lipolysis in Human Skeletal Muscle.
- 2005
-
In: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 90:2, s. 1189-1195
-
Journal article (peer-reviewed)abstract
- Release of glycerol and free fatty acids (FFA) was investigated in human skeletal muscle strips. In the basal state, glycerol and FFA were released at almost equimolar rates (0.3 nmol/ng tissue.90 min). A nonselective beta-adrenoceptor agonist, isoprenaline, caused a concentration-dependent stimulation of glycerol release, whereas FFA release was unaffected. Basal and isoprenaline-induced glycerol release correlated positively with the age of the donors (r = 0.5, P < 0.005) but not with their body mass index (P > or = 0.4). Biochemical experiments with hormone-sensitive lipase (HSL) showed that most enzyme activity was both in the cytosol and mitochondrial fraction and that it constituted the common long and active form of the protein. Electron microscopy studies in rat skeletal muscle using labeled highly specific HSL antibodies verified the cytosolic location of HSL and, furthermore, indicated an accumulation of HSL-adjoining mitochondria. These results suggest that FFA produced in myocytes during catecholamine-induced lipolysis are retained by the muscle and, therefore by inference, reused. It is conceivable that efficient hydrolysis of acylglycerol by HSL located in the cytosol as well as near the mitochondria may facilitate mitochondrial FFA oxidation. In addition, muscle lipolysis activity increases during aging and may be independent of total body fat.
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| 28. |
- Fioravanti, Elisa, et al.
(author)
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Experimental overview of the PANDA experiment
- 2014
-
In: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 503
-
Journal article (peer-reviewed)abstract
- The physics program of the (anti-Proton ANhiliation ar DArmstadt) experiment will address various questions related to the strong interactions by employing a multi-purpose detector system at the High Energy Storage Ring (HESR) for anti-protons of the upcoming Facility for Anti-proton and Ion Research (FAIR). The excellent antiproton beam resolution of Δp/p ~ 10−5 and the high luminosity =2×1032cm−2 s−1 will allow the precise measurement of the charmonium and open charm spectroscopy, the search for exotic hadrons like multiquarks, glueballs and hybrids, the study of in-medium modifications of hadrons and the nucleon structure.
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| 29. |
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| 30. |
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| 31. |
- Frisén, Marianne, 1943, et al.
(author)
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Semiparametric estimation of outbreak regression
- 2010
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In: Statistics: A Journal of Theoretical and Applied Statistics. - : Informa UK Limited. - 0233-1888. ; 44:2, s. 107-117
-
Journal article (peer-reviewed)abstract
- A regression may be constant for small values of the independent variable (for example time), but then a monotonic increase starts. Such an ‘outbreak’ regression is of interest for example in the study of the outbreak of an epidemic disease. We give the least square estimators for this outbreak regression without assumption of a parametric regression function. It is shown that the least squares estimators are also the maximum likelihood estimators for distributions in the regular exponential family such as the Gaussian or Poisson distribution. The approach is thus semiparametric. The method is applied to Swedish data on influenza, and the properties are demonstrated by a simulation study. The consistency of the estimator is proved.
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| 32. |
- Gerhardsson, Lars, 1952, et al.
(author)
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Work-related exposure to organic solvents and the risk for multiple sclerosis-a systematic review
- 2021
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In: International Archives of Occupational and Environmental Health. - : Springer Science and Business Media LLC. - 0340-0131 .- 1432-1246. ; 94:2, s. 221-229
-
Journal article (peer-reviewed)abstract
- Purpose Multiple sclerosis (MS) is a chronic progressive neurological disorder. Several environmental factors have been discussed as possible causing agents, e.g. organic solvents, whose impact on the disease is analysed in this review. Methods Systematic search strategies were used to identify high-quality studies of workers exposed to organic solvents, published up to September 30, 2019, in databases, such as PubMed, Cochrane library and Scopus. The exposure was in most studies obtained by questionnaires, supplemented with telephone interviews. The diagnosis MS was mainly detemined following a thorough neurological examination. Finally, fourteen case-control studies and two cohort studies met the inclusion criteria and were included in the meta-analysis. Random effects models were used to pool the results of the studies. Results The odds ratios from the 14 case-control studies included in the meta-analysis ranged from 0.12-4.0. Five case-control studies and one cohort study showed a significant association between the development of multiple sclerosis and exposure to organic solvents. The results from the other nine case-control studies and from one of the two cohort studies did not reach statistical significance. The pooled data from the 14 case-control studies gave an OR of 1.44 (95% CI 1.03-1.99), which shows a moderately increased risk of developing MS after exposure to organic solvents. Conclusions The final interpretation of the result is that organic solvents may be slightly associated with an increased risk to develop MS. In addition, other factors, e.g. genetic markers and smoking, may contribute to the development of the disease.
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| 33. |
- Granlund, Moa Z., 1983-, et al.
(author)
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Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel
- 2014
-
In: Applied Catalysis B. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 154, s. 386-394
-
Journal article (peer-reviewed)abstract
- The objective of this paper was to study the influence three promoters (Co, La, Mn) had on the catalytic activity of Rh-based catalysts for autothermal reforming of diesel. The catalysts were supported on CeO2ZrO2 and the loading was 1 wt.% Rh and 6 wt.% promoter. The catalytic activity was evaluated in a monolith bench scale reactor with Swedish Environmental diesel, MK1. The process parameters employed at the ATR experiments were; O-2/C similar to 0.45, H2O/C similar to 2.5 and GHSV similar to 50,000h(-1), meanwhile the reactor temperature was ramped from 700 degrees C to 950 degrees C. The catalysts were compared based on their fuel conversion, H-2 yield and the selectivity of different short-chain hydrocarbons. The results showed that all three catalysts had both high fuel conversion and H-2 yield in the optimal ATR operation temperatures. The H-2 yield and fuel conversion were increasing in the order Rh/Mn, Rh/La, Rh/Co. To get further insight in the difference between the materials the fresh and aged catalytic materials were characterized. The characterization methods used were H-2-temperature programmed reduction (H-2-TPR), powder X-ray diffraction (XRD), and BET surface measurements. The BET surface measurements showed that promotion with La gave improved thermal stability of the material. The XRD showed a high dispersion of all metals except Co, which was present as crystals in the size range of the particles of the support.
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| 34. |
- Granlund, Moa Z., et al.
(author)
-
Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel : Aging and characterization
- 2015
-
In: Applied Catalysis B. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 172, s. 145-153
-
Journal article (peer-reviewed)abstract
- In this study, three bimetallic catalysts are evaluated for autothermal reforming (AIR) of fuels (1 wt.% Rh and 6 wt.% X (X= Co, La or Mn) supported on high-surface area CeO2-ZrO2). The catalysts are aged for approximately 35 h and carefully characterized both as fresh and aged materials. The objective is to illuminate the changes in material properties after time on stream as well as the differences among the materials. The changes in material properties are evaluated by H-2-TPR, BET surface area analysis, TEM, SEM, and STEM. The material's tendency to coke is investigated by TPO analysis. The three materials exhibit promising initial activity. However, the Co-promoted sample decreases sharply in activity after 25 h of operation. Meanwhile, the other two materials display a more stable activity throughout the evaluated time. The deactivation of the Co-promoted material could be linked to the high amount of coke deposited during operation. Based on the results from the activity evaluation and characterization, the material promoted with lanthanum displays the most promising results. The addition of lanthanum resulted in a catalyst that was both stable and had high activity, even though a low rhodium loading is used. The material also shows superior thermal resistance compared to the other two materials. In addition, the tendency to coke is significantly lower compered to the other materials, which is especially beneficial when dealing with AIR of complex fuels.
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| 35. |
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| 36. |
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| 37. |
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| 38. |
- Iazzi, Felice, et al.
(author)
-
Doubly strange system physics with antiprotons at PANDA
- 2014
-
In: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 71
-
Journal article (peer-reviewed)abstract
- The study of the doubly strange hyper-systems represents a step forward in understanding the unexplored world of the strange matter in the frame of a better knowledge of the hyperon-nucleon and hyperon-nucleus interaction. The production of double hyper-systems, up to now, have been based on the use of kaon beams through a double strangeness exchange reaction. A new technique has been designed by the PANDA Collaboration, which will use the antiprotons at 3 GeV/c of the HESR facility at FAIR to create doubly strange hyperons and drive them into nuclear targets. This technique requires the use of 2 targets, located inside and outside the beam pipe. In spite of the constraints arising from the presence of a solid target inside an antiproton ring, the technique looks promising in terms of rate of hyperons and hyper-nuclei produced. After a review of the physics items that will be investigated in the hyper-nuclear section of PANDA experiment, the characteristics of the antiprotons facility, the results of the feasibility study of the 2-target technique, the design of the hyper-nuclear set-up in PANDA and the expected rates of the double hyper-nuclei will be presented.
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| 39. |
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| 40. |
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| 41. |
- Jeppson, Kjell, 1947, et al.
(author)
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Theory of a room-temperature silicon quantum dot device as a sensitive electrometer
- 2004
-
In: Journal of Applied Physics. - Melville, NY : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 95:1, s. 323-326
-
Journal article (peer-reviewed)abstract
- We consider theoretically the use of a room-temperature silicon quantum dot based device for electrometer applications. The low power device includes two split gates that quantize the electronic energy levels in the emitter and collector regions. The base consists of a silicon quantum dot buried in silicon dioxide. The small size of the dotand quantization of the states in the leads combined to allow the device to operate at room temperature. The nonlinear current-voltage characteristics can be significantly altered by small changes to the potential of the split gates. Power dissipation in the device therefore changes with the split gate voltage, and this can be exploited in electrometerapplications. A simple model of the power dissipated when the device is part of a microwave resonant inductor-resistor-capacitor tank circuit suggests that large changes indevice power can be achieved by changing the gate voltage, thereby forming a measurable signal. We also demonstrate that the power dissipation in the device changes as the base width is varied, and that the current through the device increases exponentially with a decrease in base width. (©2004 American Institute of Physics)
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| 42. |
- Karatzas, Xanthias, et al.
(author)
-
Autothermal reforming of low-sulfur diesel over bimetallic RhPt supported on Al(2)O(3), CeO(2)-ZrO(2), SiO(2) and TiO(2)
- 2011
-
In: Applied Catalysis B. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 106:3-4, s. 476-487
-
Journal article (peer-reviewed)abstract
- The objective of this paper is to study and clarify the role of selected supports (both reducible and non-reducible) on the activity, selectivity and stability of RhPt-based catalyst for diesel reforming. Autothermal reforming (AIR) of low-sulfur diesel (S similar to 6 ppm, C/H similar to 6.43 (w/w)), H(2)O/C similar to 2.5, O(2)/C similar to 0.49, was tested at bench scale to detect differences in activity for catalysts consisting of 1 wt% Rh and 1 wt% Pt supported on alumina, ceria-zirconia (17.5 wt% ceria), silica and titania. Promoters in the form of MgO. Y(2)O(3), La(2)O(3), CeO(2) and ZrO(2), ranging from 4 wt% to 10 wt%, were also added onto the supports to detect differences in catalyst activity in terms of diesel conversion, CO(2) selectivity, and hydrogen and ethylene production. All metals were added sequentially onto the support by the incipient wetness technique and washcoated on 400 cpsi cordierite monolithic carriers with dimensions d = 17.8 mm, l=30.5 mm. The product gas analysis, using FTIR and NDIR, showed that RhPt/CeO(2)-ZrO(2) was found to be most active for AIR of diesel since a fuel conversion close to 98% was obtained. Furthermore, the catalyst activity of the unpromoted samples, in terms of diesel conversion, increased in the following order: RhPt/SiO(2) < RhPt/TiO(2) < RhPt/Al(2)O(3) < RhPt/CeO(2)-ZrO(2). The addition of promoters was found to be insignificant as well as having a negative impact on the catalyst performance in most cases, except for the alumina-promoted sample. The addition of 10 wt% La(2)O(3) on RhPt/Al(2)O(3) was found to enhance diesel conversion, hydrogen productivity as well as lower the ethylene concentration from 3700 ppm to less than half that value. The latter observation was confirmed by O(2)-TPO analysis of aged powder samples where lower loads of coke were present than on the La-promoted sample. The morphology, surface and bulk properties of RhPt/CeO(2)-ZrO(2) were closely examined in order to provide a possible correlation between the activity and characterization results. N(2)-BET analysis showed that the surface area of RhPt/CeO(2)-ZrO(2) was 64 m(2)/g, while the silica samples exhibited the highest area, similar to 137-185 m(2)/g. Hence, the difference in the surface areas was not enough to explain the trends observed in the activity measurements. XRD analysis of RhPt/CeO(2)-ZrO(2) showed crystalline phases characteristic of zirconia, most likely tetragonal. Also, the diffractogram did not reveal any Rh or Pt peaks indicating that the noble metal particles are highly dispersed on the support. In contrast, peaks ascribed to metallic Pt (similar to 30-46 nm) were clearly visible on the XRD patterns taken from all the other supported samples. H(2)-TPR analysis of RhPt/CeO(2)-ZrO(2) showed reduction peaks ascribed to Rh(i)O(x) species as well as a minor hydrogen spillover effect on the support to be present at T=120 degrees C and 450 degrees C, respectively. Also, the hydrogen consumption of the Rh(i)O(x) species was the highest compared to the other supported RhPt samples. TEM analysis performed on fresh RhPt/CeO(2)-ZrO(2) showed that the Rh(i)O(x) and Pt particles were highly dispersed on the support, both with particle sizes in the vicinity of similar to 5-15 nm. Rh species was found on ceria and zirconia, while Pt was present mainly on the ceria layer possibly in the form of Pt-O-Ce bonds. H(2)-chemisorption analysis measured at T similar to 40 degrees C shows similar Rh dispersion results. To summarize, the higher activity results of RhPt/CeO(2)-ZrO(2) for AIR of diesel, compared to other supported catalysts, may be ascribed to the higher reducibility of Rh(i)O(x) species as well as the superior Rh and Pt dispersion. Also, the support contribution, in particular ceria, is believed to promote water gas-shift activities as well as reduce coke deposits on the catalyst surface.
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| 43. |
- Karatzas, Xanthias, et al.
(author)
-
Microemulsion and incipient wetness prepared Rh-based catalyst for diesel reforming
- 2011
-
In: Catalysis Today. - : Elsevier BV. - 0920-5861 .- 1873-4308. ; 175:1, s. 515-523
-
Journal article (peer-reviewed)abstract
- The role of the catalyst preparation technique was investigated for diesel reforming. Reverse microemulsion (ME) and incipient wetness (IW) techniques were used for the preparation of Rh-based monolithic catalysts that were employed for hydrogen generation of low-sulfur diesel via autothermal reforming (ATR). The washcoat of the tested catalysts consisted of 0.5 wt% Rh, 1 wt% Rh, and 1: 1 wt% Rh: Pt supported on gamma-alumina. All washcoats were deposited on 400 cpsi cordierite monoliths. The reaction condition was T(feed) = 650 degrees C, H(2)O/C similar to 2.5, O(2)/C similar to 0.49, TOS = 3 h, GHSV similar to 13 000 h(-1) and P = 1 atm. Fresh and aged powder samples of the catalyst were characterized by N(2)-BET, H(2) chemisorption, XRD, H(2)-TPR, O(2)-TPO and TEM. The activity results established that Rh and RhPt formulations, prepared by ME and IW, are highly active for ATR of diesel where fuel conversions above 92% were obtained. FTIR and NDIR analysis also showed that the highest formation of ethylene was found in the product gas stream from the bimetallic samples indicating that RhPt/Al(2)O(3) is less resistant towards carbon deposition. The latter observation was confirmed by O(2)-TPO analysis of the aged samples where high loads of coke were found both on the active metals and on the support. Interestingly, these effects were less significant on the ME samples. The characterization results clearly showed differences in morphology between the ME and the IW samples. N(2)-BET analysis showed that higher surface area, similar to 268-285 m(2)/g, was obtained with the ME samples. Also, H(2) chemisorption analysis showed that the rhodium dispersion was similar to 10% higher for the ME samples (H/Rh similar to 60-66%). XRD analysis showed that crystalline phases of gamma-alumina were present on all samples. The diffractograms also showed small traces of metallic Pt (similar to 16-30 nm) in the bimetallic samples. H(2)-TPR analysis, showed peaks ascribed to bulk rhodium oxides and rhodium aluminates. It was also noted that the addition of Pt on the support lowered the reducibility of the different rhodium species. TEM analysis performed on the fresh and aged ME and IW bimetallic samples showed mainly Rh(x)Pt(1-x) alloys with an average particle size of similar to 20-50 nm were present on the alumina support. Also, for the aged samples, no sintering effects were noted. Furthermore, rhodium was found to switch oxidation state from e. g. Rh(3+) to Rh(0) while Pt remained in the metallic state.
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| 44. |
- Keros, Victoria, et al.
(author)
-
Vitrification versus controlled-rate freezing in cryopreservation of human ovarian tissue
- 2009
-
In: Human Reproduction. - : Oxford University Press (OUP). - 0268-1161 .- 1460-2350. ; 24:7, s. 1670-1683
-
Journal article (peer-reviewed)abstract
- BACKGROUND: Controlled-rate freezing of ovarian cortical tissue for preservation of fertility among young women facing chemo- or radio-therapy is a widely accepted procedure. To improve the method for cryopreservation of ovarian tissue, particularly the stroma, we carried out a systematic comparison of vitrification versus slow programmed freezing. METHODS: Ovarian tissue from 20 women, donated during Caesarean section, was used for parallel comparison of survival and detailed light and electron microscopic (EM) morphology of oocytes, granulosa cells and ovarian stroma after freezing (slow freezing and vitrification), thawing and 24-h culture. Using tissue obtained from the same patient, we compared four cryopreservation protocols and fresh tissue. The cryoprotectants used in slow freezing were 1,2-propanediol (PrOH)-sucrose and ethylene glycol (EG)-sucrose. For vitrification, tissues were incubated for 5 or 10 min in three solutions containing a combination of dimethyl sulphoxide (DMSO), PrOH, EG and polyvinylpyrrolidone (PVP). RESULTS: Cryopreservation using controlled-rate freezing and vitrification preserved the morphological characteristics of ovarian tissue generally well. As revealed by morphological analysis, particularly EM, the ovarian stroma was significantly better preserved after vitrification than after slow freezing (P < 0.001). The follicles were similarly preserved after all freezing methods. CONCLUSIONS: Vitrification using a combination of PrOH, EG, DMSO and PVP was comparable to slow freezing in terms of preserving follicles in human ovarian tissue. Ovarian stroma had significantly better morphological integrity after vitrification than after controlled-rate freezing.
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| 45. |
- Kliemt, Ralf, et al.
(author)
-
The PANDA experiment
- 2015
-
In: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 599:1
-
Journal article (peer-reviewed)abstract
- The PANDA (anti-Proton ANnihiliation at DArmstadt) experiment will be a multipurpose apparatus at the future Facility for Antiproton and Ion Research (FAIR) at Darmstadt. Anti-proton induced reactions with 1.5 to 15 GeV/c beam momentum at high luminosities of up to 2•10(32)/(s•cm(2)) will be investigated. Exclusive detection of whole events with almost 4π acceptance and high precision are needed for the broad physics program. The focus lies on studying the strong interaction in the charm region, by charmonium, open-charm and baryon spectroscopy, and includes the search for glueballs, hybrids and other exotics, hypernuclear physics, nucleon structure studies as well as in-medium modifications of hadrons.
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| 46. |
- Ma, Binsong, et al.
(author)
-
A new method for electron momentum reconstruction in the PANDA experiment
- 2014
-
In: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 503
-
Journal article (peer-reviewed)abstract
- The Kalman Filter in existing PANDARoot framework of experiment is not optimally suited for electrons, for which the highly non-Gaussian Bremsstrahlung process yields a tail in the momentum resolution distribution. A new method was therefore developed to improve the electron momentum reconstruction with an event by event procedure. The improvements of the electron momentum resolution will be shown. The interest of the method for the electromagnetic channels studies will also be presented.
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| 47. |
- Mertens, Marius, et al.
(author)
-
Triplet based online track finding in the PANDA-STT
- 2014
-
In: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 503
-
Journal article (peer-reviewed)abstract
- The PANDA-Experiment at the future FAIR facility in Darmstadt will study antiproton-proton collisions in a fixed-target setup with a phase-space cooled antiproton beam with a momentum from 1.5 to 15 GeV/c at a nominal interaction rate of 2 · 107 s−1. The data acquisition of the detectors has to run in a triggerless mode and the physics events of interest are identified by an online event filter. Tracking information is a key input for the event filter to distinguish signal events from background. A variety of tracking algorithms is foreseen to process the different track topologies. The so-called Triplet Finder, which is presented here, is a track finding algorithm based on the central straw tube tracker (STT) of PANDA. The algorithm focuses on mathematical simplicity and robustness to allow an online processing of the incoming detector hits. The algorithm and results of a proof-of-concept implementation are presented.
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| 48. |
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| 49. |
- Nilsson, Marita, et al.
(author)
-
Catalytic properties of Pd supported on ZnO/ZnAl2O4/Al2O3 mixtures in dimethyl ether autothermal reforming
- 2009
-
In: Applied Catalysis B. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 86:02-jan, s. 18-26
-
Journal article (peer-reviewed)abstract
- The catalytic properties of Pd supported on mixtures of zinc oxide, zinc aluminate, and alumina, prepared from gamma-alumina and zinc nitrate, were studied for autothermal reforming (ATR) of dimethyl ether (DME). The performance of the catalysts was tested in a small-scale reactor, using cordierite monoliths as substrate. The catalysts exhibited high activity and generated hydrogen-rich product gases with CO concentrations below 5 vol.% in the temperature range between 350 and 450 degrees C (at O-2:DME = 0.7, H2O:DME = 2.5, and GHSV = 15000 h(-1)). The highest DME conversion was obtained for a catalyst in which the support comprised mainly ZnAl2O4. Physical mixing of the catalysts with gamma-Al2O3 resulted in increased DME conversion but a lowering of the CO2 selectivity. The catalysts were characterized by CO chemisorption, liquid nitrogen adsorption, temperature-programmed desorption of ammonia, temperature-programmed reduction, transmission electron microscopy, and X-ray diffraction. It was found that decreasing surface area and decreasing number of acid sites, caused by thermal treatment during generation of the supports, did not affect the activity negatively. The high CO2 selectivity of the catalysts was correlated with PdZn alloy formation.
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| 50. |
- Norlin, Maria, et al.
(author)
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Androgen receptor-mediated regulation of the anti-atherogenic enzyme CYP27A1 involves the JNK/c-jun pathway
- 2011
-
In: Archives of Biochemistry and Biophysics. - : Elsevier BV. - 0003-9861 .- 1096-0384. ; 506:2, s. 236-241
-
Journal article (peer-reviewed)abstract
- CYP27A1, an enzyme with several important roles in cholesterol homeostasis and vitamin D3 metabolism, has been ascribed anti-atherogenic properties. This study addresses an important problem regarding how this enzyme, involved in cholesterol metabolism in the liver and peripheral tissues, is regulated. Our results identify the human CYP27A1 gene as a new target for the JNK/c-jun pathway. Initial experiments showed that an inhibitor of c-Jun N-terminal kinase (JNK) downregulated basal CYP27A1 promoter activity whereas overexpression of JNK slightly enhanced promoter activity. Androgen receptor (AR)-mediated upregulation of mRNA levels and endogenous enzyme activity was recently reported. In the present study, the AR antagonist nilutamide blocked the androgen induction of CYP27A1. The present data revealed that inhibition of the JNK/c-jun pathway abolishes the AR-mediated effect on CYP27A1 transcription and enzyme activity, whereas overexpression of JNK markedly increased androgenic upregulation of CYP27A1. In conclusion, the current results indicate involvement of the JNK/c-jun pathway in AR-mediated upregulation of human CYP27A1. The link to JNK signaling is interesting since inflammatory processes may upregulate CYP27A1 to clear cholesterol from peripheral tissues.
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