CP Violation Makes Left-Right Symmetric Extensions With Non-Hermitian Mass Matrices Appear Unnatural

Following a similar recent analysis for CP violation in the electroweak sector of the standard model, we estimate the naturalness of a magnitude of CP violation (measured by the Jarlskog invariant J) close to the observed value in extensions of the standard model with left-right symmetry, such as the Pati-Salam model, where quark mass matrices are not Hermitian in general. We construct a simple and natural measure on the space of complex matrices which is both geometrically motivated and uses the observed quark mass hierarchy. We find that, unlike in the case of the standard model where the observed value for J seemed rather typical, one would now expect to observe |J|< 10^{-7}, clearly in conflict with the observed value J $\approx$ 3 x 10^{-5}. The crucial difference in the calculation lies in the non-Hermiticity of mass matrices that modifies the measure. We conclude that one would need additional assumptions modifying the measure to reproduce the observed value, and that in this sense the standard model is preferred to certain classes of left-right symmetric extensions: It does not need additional assumptions to explain the magnitude of CP violation.Comment: 17 pages, corrected minor typos, version to appear in Phys. Rev.

Classical general relativity as BF-Plebanski theory with linear constraints

We investigate a formulation of continuum 4d gravity in terms of a constrained BF theory, in the spirit of the Plebanski formulation, but involving only linear constraints, of the type used recently in the spin foam approach to quantum gravity. We identify both the continuum version of the linear simplicity constraints used in the quantum discrete context and a linear version of the quadratic volume constraints that are necessary to complete the reduction from the topological theory to gravity. We illustrate and discuss also the discrete counterpart of the same continuum linear constraints. Moreover, we show under which additional conditions the discrete volume constraints follow from the simplicity constraints, thus playing the role of secondary constraints.Comment: 16 pages, revtex, changed one cross-reference in sect. IIIC to match journal versio

Structuring the PA process: impact on feedback quality

The present study examines the impact of structuring the peer assessment process in a wiki-based CSCL-environment. Three conditions are involved: a non-structured, a basic structured, and an elaborated structured peer feedback condition. The main aim of this study is to foster insight into the aspect of peer feedback quality by focusing on the impact of the level of structuring and on the implemented measures to assess peer feedback by both peers and instructor

Comparison of electrode impedances of Pt, PtIr (10% Ir) and Ir-AIROF electrodes used in electrophysiological experiments

In tissue impedance measurements with the 4-electrode assembly, unexpected difficulties may occur because a combination of electrode impedance and stray capacitance in the array of four electrodes, can lead to serious measuring failures in the low-frequency range. An optimal solution to this problem can be obtained if the electrode impedances are frequency independent. A comparative study of the electrode impedances of Pt and PtIr electrodes and of a new electrode material (Ir-AIROF) is reported. It is shown that the impedance of Ir-AIROF electrodes is relatively low and almost frequency independent. Therefore the use of Ir-AIROF electrodes provides a solution to the problem mentioned above

Context-driven progressive enhancement of mobile web applications: a multicriteria decision-making approach

Personal computing has become all about mobile and embedded devices. As a result, the adoption rate of smartphones is rapidly increasing and this trend has set a need for mobile applications to be available at anytime, anywhere and on any device. Despite the obvious advantages of such immersive mobile applications, software developers are increasingly facing the challenges related to device fragmentation. Current application development solutions are insufficiently prepared for handling the enormous variety of software platforms and hardware characteristics covering the mobile eco-system. As a result, maintaining a viable balance between development costs and market coverage has turned out to be a challenging issue when developing mobile applications. This article proposes a context-aware software platform for the development and delivery of self-adaptive mobile applications over the Web. An adaptive application composition approach is introduced, capable of autonomously bypassing context-related fragmentation issues. This goal is achieved by incorporating and validating the concept of fine-grained progressive application enhancements based on a multicriteria decision-making strategy

Repeated Job Quits: Stepping Stones or Learning about Quality?

Despite the fact that worker quits are often associated with wage gains and higher overall job satisfaction, many workers quit once again within one or two years after changing jobs initially. Such repeated job quit behavior may arise as a stepping stone to better quality jobs (Burdett, 1978) or as a response to unexpectedly low job quality (Jovanovic, 1979). This paper tests the validity of both explanations using data from the UK labor market in order to improve our understanding of job search behavior. Results from panel estimations of job quits and job satisfaction illustrate that the labor market is characterized by elements of both explanations. More specifically, a variance decomposition shows that the stepping stone model explains 80 percent of repeated job quit behavior; the remaining 20 percent is the result of learning about job quality. Hence, workers appear to need several job quits to find their most preferred job and multiple job quits serve as a stepping stone to more satisfaction at work.labor mobility, job satisfaction, job search

Classical GR as a topological theory with linear constraints

We investigate a formulation of continuum 4d gravity in terms of a constrained topological (BF) theory, in the spirit of the Plebanski formulation, but involving only linear constraints, of the type used recently in the spin foam approach to quantum gravity. We identify both the continuum version of the linear simplicity constraints used in the quantum discrete context and a linear version of the quadratic volume constraints that are necessary to complete the reduction from the topological theory to gravity. We illustrate and discuss also the discrete counterpart of the same continuum linear constraints. Moreover, we show under which additional conditions the discrete volume constraints follow from the simplicity constraints, thus playing the role of secondary constraints. Our analysis clarifies how the discrete constructions of spin foam models are related to a continuum theory with an action principle that is equivalent to general relativity.Comment: 4 pages, based on a talk given at the Spanish Relativity Meeting 2010 (ERE2010, Granada, Spain