| 1. |
- Adcox, K, et al.
(författare)
-
PHENIX detector overview
- 2003
-
Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 499:2-3, s. 469-479
-
Tidskriftsartikel (refereegranskat)abstract
- The PHENIX detector is designed to perform a broad study of A-A, p-A, and p-p collisions to investigate nuclear matter under extreme conditions. A wide variety of probes, sensitive to all timescales, are used to study systematic variations with species and energy as well as to measure the spin structure of the nucleon. Designing for the needs of the heavy-ion and polarized-proton programs has produced a detector with unparalleled capabilities. PHENIX measures electron and muon pairs, photons, and hadrons with excellent energy and momentum resolution. The detector consists of a large number of subsystems that are discussed in other papers in this volume. The overall design parameters of the detector are presented. (C) 2002 Elsevier Science B.V. All rights reserved.
|
|
| 2. |
- Abt, I, et al.
(författare)
-
Inclusive V-0 production cross sections from 920 GeV fixed target proton-nucleus collisions
- 2003
-
Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 29:2, s. 181-190
-
Tidskriftsartikel (refereegranskat)abstract
- Inclusive differential cross sections dsigma(pA)/dx(F) and dsigma(pA)/dp(t)(2) for the production of K-S(0), Lambda, and (&ULambda;) over bar particles are measured at HERA in proton-induced reactions on C, Al, Ti, and W targets. The incident beam energy is 920 GeV, corresponding to roots = 41.6 GeV in the proton-nucleon system. The ratios of differential cross sections dsigma(pA)(K-S(0))/dsigma(pA)(Lambda) and dsigma(pA)((&ULambda;) over bar)/dsigma(pA) (Lambda) are measured to be 6.2 +/- 0.5 and 0.66 +/- 0.07, respectively, for x(F) approximate to -0.06. No significant dependence upon the target material is observed. Within errors, the slopes of the transverse momentum distributions da,Ald t also show no significant dependence upon the target material. The dependence of the extrapolated total cross sections sigma(pA) on the atomic mass A of the target material is discussed, and the deduced cross sections per nucleon sigma(pN) are compared with results obtained at other energies.
|
|
| 3. |
- Abt, I, et al.
(författare)
-
Measurement of the b(b)over-bar production cross section in 920 GeV fixed-target proton-nucleus collisions
- 2003
-
Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 26:3, s. 345-355
-
Tidskriftsartikel (refereegranskat)abstract
- Using the HERA-B detector, the b (b) over bar production cross section has been measured in 920 GeV proton collisions on carbon and titanium targets. The b (b) over bar production was tagged via inclusive bottom quark decays into J/psi by exploiting the longitudinal separation of J/psi --> l(+)l(-) decay vertices from the primary proton-nucleus interaction. Both e(+)e(-) and mu(+)mu(-) channels have been reconstructed and the combined analysis yields the cross section sigma(b (b) over bar) = 32(-12)(+14)(stat) (+6)(-7)(sys) nb/nucleon.
|
|
| 4. |
- Aleksandrov, D., et al.
(författare)
-
Halo excitations in fragmentation of He-6 at 240 MeV/u on carbon and lead targets
- 2000
-
Ingår i: Nuclear Physics A. - 0375-9474. ; 669:1-2, s. 51-64
-
Tidskriftsartikel (refereegranskat)abstract
- Dissociation of a 240 MeV/u beam of He-6, incident on carbon and lead targets, has been studied in kinematically complete experiments to investigate low-lying excitation modes in the halo nucleus He-6. It is shown that alignment effects characterize the inelastic scattering and allow an unambiguous assignment of the spin of a narrow resonance observed in the excitation energy spectrum. The differential cross sections for the He-6 inelastic scattering on carbon and lead targets were deduced from the measured moments of the two neutrons and the a-particle. An analysis of these distributions shows that quadrupole and, possibly, monopole excitations characterize the hadronic interaction, while the dipole mode is dominating in Coulomb dissociation. Neither theoretically predicted new resonance states in He-6 nor nuclear excitation of a dipole mode were found. Direct evidence has been obtained for strong suppression of Coulornb post-acceleration in direct Coulomb breakup in a lead target.
|
|
| 5. |
|
|
| 6. |
- Blomberg, Lars G., et al.
(författare)
-
EMMA - the electric and magnetic monitor of the aurora on Astrid-2
- 2004
-
Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 22:1, s. 115-123
-
Tidskriftsartikel (refereegranskat)abstract
- The Astrid-2 mission has dual primary objectives. First, it is an orbiting instrument platform for studying auroral electrodynamics. Second, it is a technology demonstration of the feasibility of using micro-satellites for innovative space plasma physics research. The EMMA instrument, which we discuss in the present paper, is designed to provide simultaneous sampling of two electric and three magnetic field components up to about 1 kHz. The spin plane components of the electric field are measured by two pairs of opposing probes extended by wire booms with a separation distance of 6.7 m. The probes have titanium nitride (TiN) surfaces. which has proved to be a material with excellent properties for providing good electrical contact between probe and plasma. The wire booms are of a new design in which the booms in the stowed position are wound around the exterior of the spacecraft body. The boom system was flown for the first time on this mission and worked flawlessly. The magnetic field is measured by a tri-axial fluxgate sensor located at the tip of a rigid. hinged boom extended along the spacecraft spin axis and facing away from the Sun. The new advanced-design fluxgate magnetometer uses digital signal processors for detection and feedback, thereby reducing the analogue circuitry to a minimum. The instrument characteristics as well as a brief review of the science accomplished and planned are presented.
|
|
| 7. |
|
|
| 8. |
- Nylandsted Larsen, A., et al.
(författare)
-
Tin-vacancy acceptor levels in electron-irradiated n-type silicon
- 2000
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 62:7, s. 4535-4544
-
Tidskriftsartikel (refereegranskat)abstract
- Si crystals (n-type, fz) with doping levels between 1.5×1014 and 2×1016 cm-3 containing in addition ∼1018 Sn/cm3 were irradiated with 2-MeV electrons to different doses and subsequently studied by deep level transient spectroscopy, Mössbauer spectroscopy, and positron annihilation. Two tin-vacancy (Sn-V) levels at Ec-0.214 eV and Ec-0.501 eV have been identified (Ec denotes the conduction band edge). Based on investigations of the temperature dependence of the electron-capture cross sections, the electric-field dependence of the electron emissivity, the anneal temperature, and the defect-introduction rate, it is concluded that these levels are the double and single acceptor levels, respectively, of the Sn-V pair. These conclusions are in agreement with electronic structure calculations carried out using a local spin-density functional theory, incorporating pseudopotentials to eliminate the core electrons, and applied to large H-terminated clusters. Thus, the Sn-V pair in Si has five different charge states corresponding to four levels in the band gap.
|
|
| 9. |
- Petersén, Åsa, et al.
(författare)
-
Brain-derived neurotrophic factor inhibits apoptosis and dopamine-induced free radical production in striatal neurons but does not prevent cell death
- 2001
-
Ingår i: Brain Research Bulletin. - 0361-9230. ; 56:3-4, s. 331-335
-
Tidskriftsartikel (refereegranskat)abstract
- In hereditary Huntington's disease, a triplet repeat disease, there is extensive loss of striatal neurons. It has been shown that brain-derived neurotrophic factor (BDNF) protects striatal neurons against a variety of insults. We confirmed that BDNF enhances survival and DARPP-32 expression in primary striatal cultures derived from postnatal mice. Furthermore, BDNF inhibited intracellular oxyradical stress triggered by dopamine, and partially blocked basal and dopamine-induced apoptosis. Nevertheless, BDNF failed to rescue striatal neurons from dopamine-induced cell death. Therefore, BDNF inhibits free radical and apoptotic pathways in medium spiny neurons, but does so downstream from the point of commitment to cell death.
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
|
|
| 13. |
- Greiff, Lennart, et al.
(författare)
-
Mucosal output of eotaxin in allergic rhinitis and its attenuation by topical glucocorticosteroid treatment
- 2001
-
Ingår i: Clinical and Experimental Allergy. - : Wiley. - 1365-2222 .- 0954-7894. ; 31:8, s. 1321-1327
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Eotaxin is a chemokine that attracts and activates eosinophils. The present study examines the occurrence of eotaxin in nasal mucosal surface liquids in patients with seasonal allergic rhinitis without allergen exposure and during repeat allergen challenge with and without topical glucocorticosteroid treatment. The number of subepithelial eosinophils and mucosal outputs of bulk plasma (alpha2-macroglobulin) and eosinophil cationic protein (ECP) are also examined. METHODS: Twelve patients underwent daily allergen challenges for 6 days. Separately, 14 patients, who were receiving budesonide and placebo in a parallel group design, also underwent allergen challenge for 6 days. Nasal biopsies were obtained before and 24 h after the allergen challenge series, and lavages were carried out before and 15 min after selected allergen challenges. RESULTS: At baseline nasal lavage fluid levels of eotaxin correlated to levels of alpha2-macroglobulin and ECP. After the first allergen challenge there was a correlation between nasal lavage fluid levels of eotaxin and ECP. Repeat allergen exposure increased the mucosal output of eotaxin (P <0.05) and ECP (P <0.01) as well as eosinophil numbers (P <0.01), but no correlation was found between increased eosinophil numbers and eotaxin. Budesonide reduced eotaxin levels during repeat allergen challenge (P <0.05). CONCLUSIONS: Repeat allergen exposure in allergic rhinitis is associated with increased mucosal output of eotaxin. Topical budesonide attenuates this effect, suggesting the possibility that inhibitory effects on mucosal eotaxin may contribute to anti-eosinophilic actions of topical glucocorticosteroids.
|
|
| 14. |
|
|
| 15. |
- Munthe, John, et al.
(författare)
-
Distribution of atmospheric mercury species in Northern Europe: Final results from the MOE-project
- 2003
-
Ingår i: Atmospheric Environment. - 1352-2310 .- 1873-2844. ; 37:Suppl 1
-
Tidskriftsartikel (refereegranskat)abstract
- The mercury species over Europe (MOE) project was aimed at identifying sources, occurrence and atmospheric behaviour of atmospheric Hg species. Within MOE, emission measurements, ambient air measurements, process and regional-scale modelling and laboratory measurements were conducted. In this work, a summary of some of the main results is given. From the emission measurements, information on stack gas concentrations and emission factors for five coal fired power plants and three waste incinerators are presented. Results from field measurements of mercury species in ambient air at five locations in Northern Europe are presented. Examples from regional-scale atmospheric modelling are also given. The results emphasise the importance of information on Hg species for instance in emission inventories and measurement data from background sites. Furthermore, the importance of considering the role of the global cycling of mercury in future control strategies is emphasised
|
|
| 16. |
- Petersen, Sobah, et al.
(författare)
-
Requirements for an agent-based approach to support virtual enterprises
- 2004
-
Ingår i: Processes and foundations for virtual organizations. - New York, NY : Springer-Verlag New York. - 9781475762952 ; , s. 85-92
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we present the requirements for an agent-based approach to support the formation of Virtual Enterprises by analysing the approach using two industrial case studies. We believe that there are two important aspects of selecting the partners for a Virtual Enterprise; (i) matching the correct partner to the requirements, and (ii) the process in which the partners are evaluated and selected. Our analysis showed that the system must provide support for a language to represent the capabilities of the partner, the evaluation of different kinds of partners, flexibility in defining the evaluation criteria, the selection process and the negotiation process.
|
|
| 17. |
- Petersén, Åsa, et al.
(författare)
-
Expanded CAG repeats in exon 1 of the Huntington's disease gene stimulate dopamine-mediated striatal neuron autophagy and degeneration
- 2001
-
Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 10:12, s. 1243-1254
-
Tidskriftsartikel (refereegranskat)abstract
- Huntington's disease (HD) is caused by an expanded CAG repeat in exon 1 of the gene coding for the huntingtin protein. The cellular pathway by which this mutation induces HD remains unknown, although alterations in protein degradation are involved, To study intrinsic cellular mechanisms involved, To study Intrinsic to the mutation, we examined dissociated postnatally derived cultures of striatal neurons from transgenic mice expressing exon 1 of the human HD gene carrying a CAG repeat expansion. While there was no difference in cell death between wild-type and mutant littermate-derived cultures, the mutant striatal neurons exhibited elevated cell death following a single exposure to a neurotoxic concentration of dopamine, The mutant neurons exposed to dopamine also exhibited lysosome-associated responses including induction of autophagic granules and electron-dense lysosomes, The autophagic/lysosomal compartments co-localized with high levels of oxygen radicals in living neurons, and ubiquitin. The results suggest that the combination of mutant huntingtin and a source of oxyradical stress (provided in this case by dopamine) induces autophagy and may underlie the selective cell death characteristic of HD.
|
|
| 18. |
|
|
| 19. |
|
|
| 20. |
- Tiselius, Peter, 1958, et al.
(författare)
-
Functional response of Oikopleura dioica to house clogging due to exposure to algae of different sizes
- 2003
-
Ingår i: Marine Biology. - 0025-3162. ; 142:2, s. 253-261
-
Tidskriftsartikel (refereegranskat)abstract
- The functional response of the appendicularian Oikopleura dioica was investigated with a unialgal diet (Isochrysis galbana, 0-1,600 mug Cl-1) and with additions of specific concentrations of algae either smaller than the incurrent filter mesh size (Rhodomonas baltica, 90 mug Cl-1; Thalassiosira weissflogii, 60 mug Cl-1) or larger algae (Ceratium lineatum, 8 mug Cl-1; C. tripos, 52 mug C l(-1)). Clearance ranged from 0.13 to 3.3 ml mug C-1 h(-1) and followed a Michaelis-Menten curve corresponding to a maximum filtration rate (particles collected by both animal and house), FRmax = 164 ng C mug C-1 h(-1) and K-m = 64 mug C l(-1). Maximum pellet production was 9 pellets ind(-1) h(-1) and occurred at 100 mugC (-1). Pellet production was proportional to filtration rate below this level, but declined at higher concentrations. House production ranged from 0.5 to 5.5 houses ind(-1) day(-1) and the corresponding curve fit resulted in H-max = 4.6 houses ind(-1) day(-1) and K-m house = 32 mug Cl-1. Addition of edible small algae caused increased internal clogging of the houses, evidenced by significantly higher pigment concentrations in abandoned houses than in houses produced with I.. galbana as a single food. House production was not affected. In contrast, larger algae caused a significantly higher house production, but the algae were not collected on the houses. Increased levels of edible algae will not have negative effects on O. dioica at ecologically realistic concentrations. Ambient bloom concentrations of larger algae may, however, have a negative effect on the growth of O. dioica populations, owing to the compensatory increased house production.
|
|
| 21. |
|
|
| 22. |
- Vargas, C. A., et al.
(författare)
-
Importance of copepods versus appendicularians in vertical carbon fluxes in a Swedish fjord
- 2002
-
Ingår i: Marine Ecology-Progress Series. - 0171-8630. ; 241, s. 125-138
-
Tidskriftsartikel (refereegranskat)abstract
- We examined and quantified the contributions of copepods and appendicularians to the vertical flux of carbon during autumn and spring in Gullmar Fjord (west coast of Sweden). Faecal pellet-production rate was determined for major copepod and appendicularian species. In addition, house-production rates were estimated for the appendicularian Oikopleura dioica. Vertical flux of pigments, faecal carbon and appendicularian houses were measured using short-term (24 h) deployments of sediment traps at 2 depths (15 and 30 m). Copepods dominated the community biomass in both spring and autumn and their pellets dominated the faecal carbon flux. O. dioica houses with attached detritus were an important component of the biogenic carbon flux in October (15.3 mg C m(-2) d(-1)), equalling the contribution from copepods at 15 m and 50% of the flux at 30 m. At that time, we observed a loss rate of 70% d(-1) of the houses produced in the water column. In the spring, although Fritillaria borealis dominated the appendicularians, its houses did not appear to contribute to the biogenic flux. Our results suggest that oikopleurids and fritillariids may not operate equivalently in biogeochemical cycles. Because of the significant contribution of appendicularians to carbon fluxes, they should be incorporated in future flow models of coastal oceans.
|
|
