| 1. |
- Abelev, Betty, et al.
(författare)
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Long-range angular correlations on the near and away side in p-Pb collisions at root S-NN=5.02 TeV
- 2013
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 719:1-3, s. 29-41
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Tidskriftsartikel (refereegranskat)abstract
- Angular correlations between charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV for transverse momentum ranges within 0.5 < P-T,P-assoc < P-T,P-trig < 4 GeV/c. The correlations are measured over two units of pseudorapidity and full azimuthal angle in different intervals of event multiplicity, and expressed as associated yield per trigger particle. Two long-range ridge-like structures, one on the near side and one on the away side, are observed when the per-trigger yield obtained in low-multiplicity events is subtracted from the one in high-multiplicity events. The excess on the near-side is qualitatively similar to that recently reported by the CMS Collaboration, while the excess on the away-side is reported for the first time. The two-ridge structure projected onto azimuthal angle is quantified with the second and third Fourier coefficients as well as by near-side and away-side yields and widths. The yields on the near side and on the away side are equal within the uncertainties for all studied event multiplicity and p(T) bins, and the widths show no significant evolution with event multiplicity or p(T). These findings suggest that the near-side ridge is accompanied by an essentially identical away-side ridge. (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
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| 2. |
- Abelev, Betty, et al.
(författare)
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Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :11
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Tidskriftsartikel (refereegranskat)abstract
- The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.
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| 3. |
- Abelev, Betty, et al.
(författare)
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Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :7
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Tidskriftsartikel (refereegranskat)abstract
- We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%.
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| 4. |
- Boll, Rebecca, et al.
(författare)
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Imaging molecular structure through femtosecond photoelectron diffraction on aligned and oriented gas-phase molecules
- 2014
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Ingår i: Faraday Discussions. - : Royal Society of Chemistry (RSC). - 1364-5498. ; 171, s. 57-80
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Tidskriftsartikel (refereegranskat)abstract
- This paper gives an account of our progress towards performing femtosecond time-resolved photoelectron diffraction on gas-phase molecules in a pump-probe setup combining optical lasers and an X-ray free-electron laser. We present results of two experiments aimed at measuring photoelectron angular distributions of laser-aligned 1-ethynyl-4-fluorobenzene (C8H5F) and dissociating, laser-aligned 1,4-dibromobenzene (C6H4Br2) molecules and discuss them in the larger context of photoelectron diffraction on gas-phase molecules. We also show how the strong nanosecond laser pulse used for adiabatically laser-aligning the molecules influences the measured electron and ion spectra and angular distributions, and discuss how this may affect the outcome of future time-resolved photoelectron diffraction experiments.
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| 5. |
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| 6. |
- Debatin, Franziska, et al.
(författare)
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An Isoreticular Family of Microporous Metal-Organic Frameworks Based on Zinc and 2-Substituted Imidazolate-4-amide-5-imidate : Syntheses, Structures and Properties
- 2012
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 18:37, s. 11630-11640
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Tidskriftsartikel (refereegranskat)abstract
- We report on a new series of isoreticular frameworks based on zinc and 2-substituted imidazolate-4-amide-5-imidate (IFP-14, IFP=imidazolate framework Potsdam) that form one-dimensional, microporous hexagonal channels. Varying R in the 2-substitued linker (R=Me (IFP-1), Cl (IFP-2), Br (IFP-3), Et (IFP-4)) allowed the channel diameter (4.01.7 angstrom), the polarisability and functionality of the channel walls to be tuned. Frameworks IFP-2, IFP-3 and IFP-4 are isostructural to previously reported IFP-1. The structures of IFP-2 and IFP-3 were solved by X-ray crystallographic analyses. The structure of IFP-4 was determined by a combination of PXRD and structure modelling and was confirmed by IR spectroscopy and 1H MAS and 13C CP-MAS NMR spectroscopy. All IFPs showed high thermal stability (345400?degrees C); IFP-1 and IFP-4 were stable in boiling water for 7 d. A detailed porosity analysis was performed on the basis of adsorption measurements by using various gases. The potential of the materials to undergo specific interactions with CO2 was investigated by measuring the isosteric heats of adsorption. The capacity to adsorb CH4 (at 298 K), CO2 (at 298 K) and H2 (at 77 K) at high pressure were also investigated. In situ IR spectroscopy showed that CO2 is physisorbed on IFP-14 under dry conditions and that both CO2 and H2O are physisorbed on IFP-1 under moist conditions.
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| 7. |
- Feng, Yi, et al.
(författare)
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Characterization of Inkjet Printed Coplanar Waveguides for Flexible Electronics
- 2011
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Ingår i: NIP27: International Conference on Digital Printing Technologies and Digital Fabrication 2011. - : The Society for Imaging Science and Technology. - 9780892082964 ; , s. 454-457
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Konferensbidrag (refereegranskat)abstract
- The low conductivity and thin layers of the inkjet-printed metal conductors have always been a big concern in paper-based printed electronics for high frequency applications. To provide the fundamental knowledge, the high frequency characteristics of inkjet-printed coplanar waveguides on paper substrate were studied experimentally in terms of characteristic impedance and conductor losses using the time domain reflectometry technique. The influences of different printing settings and of geometric parameters on the waveguide's properties were investigated. Considering the measurement accuracy in high frequency characterization, one sample with an impedance of 51.2Ω was achieved. The electrical stability of the samples was also studied and explained. In addition, one waveguide sample was printed in a way that the pattern area with the highest current density is thickened. This variable ink-layer thickness approach has successfully been proven as a promising solution to reduce the conductor losses and yet consuming less ink.
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| 8. |
- Johansson, Henrik, 1979-
(författare)
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Fragmentation of Amino Acids and Microsolvated Peptides and Nucleotides using Electrospray Ionization Tandem Mass Spectrometry
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents three different series of high energy (keV) collision experiments as well as a brief scientific introduction to the field. In the first series, protonated glycine and leucine were collided with carbon dioxide and a beam attenuation method was applied to determine their total fragmentation cross sections. A technique was also presented for how to restore the resolution in mass spectra obtained with a hemispherical electrostatic analyzer followed by a position sensitive detector (micro-channel plate equipped with a resistive anode). In the second series of experiments, Collision Induced Dissociation (CID) and Electron Capture Induced Dissociation (ECID) studies were performed on the nucleotide adenosine 5'-monophosphate anion (AMP-) in water complexes. The two dissociation techniques revealed different fragmentation patterns and a numerical solvent evaporation model was used to interpret the spectra. It was then found that the CID and ECID processes were associated with different internal energy distributions. The third experiment concerned ECID of the protonated dipeptide glycine-alanine ([GA+H]+) in complexes with water, methanol, acetonitrile or crown ether. Depending on the attached molecular species, different ratios between the two competing channels ammonia loss and N-Cα bond cleavage were observed. Quantum chemical calculations revealed that a notable shift in the location of the captured electron occurred for the case of two acetonitriles and one crown ether compared to the bare ion and the ion in complexes with either water or methanol. Finally, this thesis will discuss developments of the electrospray ionization platform as well as the new Double ElectroStatic IonRing ExpEriment (DESIREE) facility.
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| 9. |
- Kløve, Bjørn, et al.
(författare)
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Protection of GDE related ecosystem services in future groundwater resources management: current policies, methods and future recommendations
- 2013
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Rapport (populärvet., debatt m.m.)abstract
- Groundwater dependent ecosystems have a high biodiversity and many ecosystem services and their future protection is important. At present, little information is available on the role of groundwater in ecosystems let alone criteria for ecosystem protection. This report makes a critical analysis of present knowledge and seeks for new ways to understand and manage these systems. This is needed to manage groundwater bodies as intended in the European water directives (GWD and WFD) that strive to improve the status of groundwater and surface water. The report includes issues such as sustainability, legal issues, conceptual models, risk valuation and impact assessment methods.
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| 10. |
- Kötters, Jens, et al.
(författare)
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A Database Browser based on Pattern Concepts
- 2012
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Ingår i: Formal Concept Analysis Meets Information Retrieval FCAIR 12.
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Konferensbidrag (refereegranskat)abstract
- A Galois connection is stated between a knowledge base and queries over this knowledge. Queries are stated as conjunctions. Both the knowledge and queries are represented by certain graphs. This Galois connection gives rise to lattices of pattern concepts implicitly contained in the theory (all derivable facts) over the knowledge base. The formal foundation for browsing such lattices and a realisation in terms of a prototype tool is outlined. Data types may be assigned to individual columns of tables in the database
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