1,292 research outputs found
Part III, Free Actions of Compact Quantum Groups on C*-Algebras
We study and classify free actions of compact quantum groups on unital
C*-algebras in terms of generalized factor systems. Moreover, we use these
factor systems to show that all finite coverings of irrational rotation
C*-algebras are cleft
On the efficiency of heat engines at the micro-scale and below
We investigate the thermodynamic efficiency of sub-micro-scale heat engines
operating under the conditions described by over-damped stochastic
thermodynamics. We prove that at maximum power the efficiency obeys for
constant isotropic mobility the universal law
where is the efficiency of an ideal Carnot cycle. The corresponding
power optimizing protocol is specified by the solution of an optimal mass
transport problem. Such solution can be determined explicitly using well known
Monge--Amp\`ere--Kantorovich reconstruction algorithms. Furthermore, we show
that the same law describes the efficiency of heat engines operating at maximum
work over short time periods. Finally, we illustrate the straightforward
extension of these results to cases when the mobility is anisotropic and
temperature dependent.Comment: 5 pages; revised version including the derivation of the efficiency
and of the corresponding optimal protocols in the presence of anisotropic
temperature dependent mobilit
On the origin of temperature dependence of interlayer exchange coupling in metallic trilayers
We study the influence of collective magnetic excitations on the interlayer
exchange coupling (IEC) in metallic multilayers. The results are compared to
other models that explain the temperature dependence of the IEC by mechanisms
within the spacer or at the interfaces of the multilayers. As a main result we
find that the reduction of the IEC with temperature shows practically the same
functional dendence in all models. On the other hand the influence of the
spacer thickness, the magnetic material, and an external field are quite
different. Based on these considerations we propose experiments, that are able
to determine the dominating mechanism that reduces the IEC at finite
temperatures.Comment: 8 pages, 7 figures, accepted for PR
Mechanism of temperature dependence of the magnetic anisotropy energy in ultrathin Cobalt and Nickel films
Temperature dependent FMR-measurements of Ni and Co films are analysed using
a microscopic theory for ultrathin metallic systems. The mechanism governing
the temperature dependence of the magnetic anisotropy energy is identified and
discussed. It is reduced with increasing temperature. This behavior is found to
be solely caused by magnon excitations.Comment: 3 pages, 4 figures III Joint European Magnetic Symposia, San
Sebastian, Spai
Teaching Case: Design and Development of a Special Population Resource Connection Database
Connecting people with resources is a common activity. However, special situations have unique data needs. Without the appropriate leadership and tools to manage the data, the connections may never take place. This case examines the data needs associated with providing resources and social connections for families having a member with a special need. The case provides a realistic scenario that can be used in a systems analysis and design, database development, or graduate-level management information systems course. The case focuses on developing a database to provide a support system for connecting caregivers of loved ones having special needs with people in similar circumstances, volunteers, and social and employment opportunities. Two assignment options are provided, allowing instructors to select an assignment based on course material coverage. Suggested assignments include the development of process modeling diagrams such as a data flow or swimlane diagrams and database design and development artifacts
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