3,571 research outputs found
TUBIS – Integration von Campusdiensten an der Technischen Universität Berlin
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Die IT-Landschaft der Universitäten ist historisch gewachsen. Unterschiedliche Abteilungen und Fakultäten haben jeweils für sie optimale Softwarelösungen ausgewählt und in ihre Arbeitsabläufe integriert. Die aktuellen Anforderungen an die Universitäten erfordern eine Integration der unterschiedlichen Insellösungen. Die TU-Berlin setzt hierbei auf ein eigenes Produkt, das auf Basis verschiedener Open Source-Lösungen erstellt wurde und stetig erweitert wird. Dabei werden nicht nur Daten zusammengeführt, sondern auch ein universitätsweites, rollen-basiertes Rechtesystem etabliert, das sich, wie bereits gezeigt, in unterschiedliche Anwendungen integrieren lässt
Calculating Kaon Fragmentation Functions from NJL-Jet Model
The Nambu--Jona-Lasinio (NJL) - Jet model provides a sound framework for
calculating the fragmentation functions in an effective chiral quark theory,
where the momentum and isospin sum rules are satisfied without the introduction
of ad hoc parameters. Earlier studies of the pion fragmentation functions using
the NJL model within this framework showed qualitative agreement with the
empirical parameterizations. Here we extend the NJL-Jet model by including the
strange quark. The corrections to the pion fragmentation functions and
corresponding kaon fragmentation functions are calculated using the elementary
quark to quark-meson fragmentation functions from NJL. The results for the kaon
fragmentation functions exhibit a qualitative agreement with the empirical
parameterizations, while the unfavored strange quark fragmentation to pions is
shown to be of the same order of magnitude as the unfavored light quark's. The
results of these studies are expected to provide important guidance for the
analysis of a large variety of semi-inclusive data.Comment: 9 pages, 14 figure
Agreement without A positions: Another look at Algonquian
This is the published version, also available here: http://dx.doi.org/10.1162/002438905774464304
Monte Carlo Simulations of Hadronic Fragmentation Functions using NJL-Jet Model
The recently developed Nambu-Jona-Lasinio (NJL) - Jet model is used as an
effective chiral quark theory to calculate the quark fragmentation functions to
pions, kaons, nucleons, and antinucleons. The effects of the vector mesons rho,
K* and phi on the production of secondary pions and kaons are included. The
fragmentation processes to nucleons and antinucleons are described by using the
quark-diquark picture, which has been shown to give a reasonable description of
quark distribution functions. We incorporate effects of next-to-leading order
(NLO) in the Q^2 evolution, and compare our results with the empirical
fragmentation functions.Comment: 27 pages, 13 figure
Unusual weak magnetic exchange in two different structure types: YbPtSn and YbPtIn
We present the structural, magnetic, thermodynamic, and transport properties
of the two new compounds YbPtSn and YbPtIn. X-ray powder diffraction
shows that they crystallize in different structure types, the hexagonal
ZrPtAl and the cubic Heusler type, respectively. Despite quite different
lattice types, both compounds present very similar magnetic properties: a
stable trivalent Yb, no evidence for a sizeable Kondo interaction, and
very weak exchange interactions with a strength below 1K as deduced from
specific heat . Broad anomalies in suggest short range magnetic
ordering at about 250mK and 180mK for YbPtSn and YbPtIn, respectively.
The weak exchange and the low ordering temperature result in a large
magnetocaloric effect as deduced from the magnetic field dependence of ,
making these compounds interesting candidates for magnetic cooling. In addition
we found in YbPtIn evidences for a charge density wave transition at about
290K. The occurrence of such transitions within several RETX compound
series (RE = rare earth, T = noble metal, X = In, Sn) is analyzed.Comment: 16 pages, 7 figure
Magnetic structure and dynamics of a strongly one-dimensional cobalt metal-organic framework
We investigate the magnetism of the
Co(OH)(CHO) metal-organic framework which
displays complex inorganic chains separated from each other by distances of 1
to 2 nm, and which orders at ~5.4 K. The zero-field magnetic structure is
determined using neutron powder diffraction: it is mainly antiferromagnetic but
posseses a ferromagnetic component along the -axis. This magnetic
structure persists in presence of a magnetic field. Ac susceptibility
measurements confirm the existence of a single thermally activated regime over
7 decades in frequency () whereas time-dependent relaxation
of the magnetization after saturation in an external field leads to a two times
smaller energy barrier. These experiments probe the slow dynamics of domain
walls within the chains: we propose that the ac measurements are sensitive to
the motion of existing domain walls within the chains, while the magnetization
measurements are governed by the creation of domain walls.Comment: 12 pages, 14 figure
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