CP\mathcal{CP} Violation from String Theory

We identify a natural way to embed $\mathcal{CP}$ symmetry and its violation in string theory. The $\mathcal{CP}$ symmetry of the low energy effective theory is broken by the presence of heavy string modes. $\mathcal{CP}$ violation is the result of an interplay of $\mathcal{CP}$ and flavor symmetry. $\mathcal{CP}$ violating decays of the heavy modes could originate a cosmological matter-antimatter asymmetry.Comment: 7 pages, 4 figure

Unification of Flavor, CP, and Modular Symmetries

Flavor symmetry plays a crucial role in the standard model of particle physics but its origin is still unknown. We develop a new method (based on outer automorphisms of the Narain space group) to determine flavor symmetries within compactified string theory. A picture emerges where traditional (discrete) flavor symmetries, CP-like symmetries and modular symmetries (like T-duality) of string theory combine to unified flavor symmetries. The groups depend on the geometry of compact space and the geographical location of fields in the extra dimensions. We observe a phenomenon of "local flavor groups" with potentially different flavor symmetries for the various sectors of quarks and leptons. This should allow interesting connections to existing bottom-up attempts in flavor model building.Comment: 18 pages, 3 figures; v2: minor changes, version accepted by PL

A note on discrete R symmetries in Z6-II orbifolds with Wilson lines

We re-derive the R symmetries for the Z6-II orbifold with non-trivial Wilson lines and find expressions for the R charges which differ from those in the literature.Comment: 13 pages, 3 figure

Location-Quality-aware Policy Optimisation for Relay Selection in Mobile Networks

Relaying can improve the coverage and performance of wireless access networks. In presence of a localisation system at the mobile nodes, the use of such location estimates for relay node selection can be advantageous as such information can be collected by access points in linear effort with respect to number of mobile nodes (while the number of links grows quadratically). However, the localisation error and the chosen update rate of location information in conjunction with the mobility model affect the performance of such location-based relay schemes; these parameters also need to be taken into account in the design of optimal policies. This paper develops a Markov model that can capture the joint impact of localisation errors and inaccuracies of location information due to forwarding delays and mobility; the Markov model is used to develop algorithms to determine optimal location-based relay policies that take the aforementioned factors into account. The model is subsequently used to analyse the impact of deployment parameter choices on the performance of location-based relaying in WLAN scenarios with free-space propagation conditions and in an measurement-based indoor office scenario.Comment: Accepted for publication in ACM/Springer Wireless Network

Molecular structure of the 8.0 kDa subunit of cytochrome-c reductase from potato and its Δψ-dependent import into isolated mitochondria

AbstractThe cytochrome-c reductase (EC 1.10.2.2) of the mitochondrial respiratory chain couples electron transport from ubiquinol to cytochrome c with proton translocation across the inner mitochondrial membrane. The enzyme from potato was shown to be composed of 10 subunits. Isolation and characterization of cDNA clones for the second smallest subunit reveal an open reading frame of 216 bp encoding a protein of 8.0 kDa. The protein exhibits similarities to a 7.2/7.3 kDa subunit of cytochrome-c reductase from bovine and yeast, that is localized on the intermembrane space side of the enzyme complex. It also shows similarity to a previously unidentified 7.8 kDa protein of cytochrome-c reductase from Euglena. The potato 8.0 kDa protein has a segmental structure, as its sequence can be devided into four parts, each comprising a central Arg-(Xaa)5-Val motif. N-terminal sequencing of the mature 8.0 kDa protein indicates the absence of a cleavable mitochondrial targeting sequence. Import of the in vitro synthesized 8.0 kDa protein into isolated potato mitochondria confirms the lack of a presequence and reveals a dependence of the transport on the membrane potatial Δψ across the inner mitochondrial membrane. These features are unique among the intermembrane space proteins known so far

Parameter Optimisation of a Virtual Synchronous Machine in a Microgrid

Parameters of a virtual synchronous machine in a small microgrid are optimised. The dynamical behaviour of the system is simulated after a perturbation, where the system needs to return to its steady state. The cost functional evaluates the system behaviour for different parameters. This functional is minimised by Parallel Tempering. Two perturbation scenarios are investigated and the resulting optimal parameters agree with analytical predictions. Dependent on the focus of the optimisation different optima are obtained for each perturbation scenario. During the transient the system leaves the allowed voltage and frequency bands only for a short time if the perturbation is within a certain range.Comment: 17 pages, 5 figure

Preparation, characterization and sintering behavior of barium titanate powders coated with Ba-, Ca-, Si- and Ti-containing components

An emulsion technique and spray drying were used to prepare BaTiO3 powders coated with additives. Different additive compositions (TiO2; TiO2/SiO2; CaO/TiO2/SiO2; 2BaO/TiO2/2SiO2) were used in the form of their aqueous precursor solutions. The as-received powders were compared with powders of the same composition manufactured by conventional wet-milling. The coating of the BaTiO3 powder positively influences the sintering behavior. Isothermal dilatometric measurements show that the activation energy &Delta;E of the shrinkage of the coated powders is lower than that of the powders prepared by milling. This is caused by the homogeneous distribution of the additive. The activation energy for the different additives changes in the following sequence: &Delta;E(2BaO/TiO2/2SiO2) < &Delta;E(TiO2) < &Delta;E(CaO/TiO2/SiO2) < &Delta;E(TiO2/SiO2). This sequence correlates with the amount of Ba ions necessary to diffuse out of the BaTiO3 matrix to form the secondary phases Ba2TiSi2O8 or Ba6Ti17O40, respectively