Chiral cosmic strings in supergravity

We consider F and D-term cosmic strings formed in supersymmetric theories. Supersymmetry is broken inside the string core, but restored outside. In global SUSY, this implies the existence of goldstino zero modes, and the string potentially carries fermionic currents. We show that these zero modes do not survive the coupling to gravity, due to the super Higgs mechanism. Therefore the superconductivity and chirality properties are different in global and local supersymmetry. For example, a string formed at the end of D-term inflation is chiral in supergravity but non-chiral in global SUSY.Comment: 14 pages, no figure

Challenges for chemical information extraction and text retrieval

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Classes of Byzantine Fault-Tolerant Algorithms for Dependable Distributed Systems.

This thesis concentrates on the design of new algorithms for fault-tolerant systems based on system-level hardware masking redundancy. It is argued that any system in which a reliability improvement of at least a factor 100 is required should be based on system-level hardware masking redundancy. The technique of system-level hardware masking redundancy is applicable in a redundant system consisting of a number of processors, in which the system services are replicated on the different processors, and provides resilience to a limited number of faulty processors in the system. The technique is most effective in a distributed system, since the autonomous nature and geographical distribution of the processors in such a system largely contribute to achieve independency between failures of different processors, which improves the reliability of the system

Unitarity and predictiveness in new Higgs inflation

In new Higgs inflation the Higgs kinetic terms are non-minimally coupled to the Einstein tensor, allowing the Higgs field to play the role of the inflaton. The new interaction is non-renormalizable, and the model only describes physics below some cutoff scale. Even if the unknown UV physics does not affect the tree level inflaton potential significantly, it may still enter at loop level and modify the running of the Standard Model (SM) parameters. This is analogous to what happens in the original model for Higgs inflation. A key difference, though, is that in new Higgs inflation the inflationary predictions are sensitive to this running. Thus the boundary conditions at the EW scale as well as the unknown UV completion may leave a signature on the inflationary parameters. However, this dependence can be evaded if the kinetic terms of the SM fermions and gauge fields are non-minimally coupled to gravity as well. Our approach to determine the model's UV dependence and the connection between low and high scale physics can be used in any particle physics model of inflation.Comment: 21+6 pages, 1 figure; final version accepted by the journal, improvements of section

Electroweak stability and non-minimal coupling

The measured values of the Higgs and top quark mass indicate that the electroweak vacuum is metastable if there is no new physics below the Planck scale. This is at odds with a period of high scale inflation. A non-minimal coupling between the Higgs field and the Ricci scalar can stabilize the vacuum as it generates a large effective Higgs mass during inflation. We consider the effect of this coupling during preheating, when Higgs modes can be produced very efficiently due to the oscillating Ricci scalar. We compute their effect on the effective potential and the energy density. The Higgs excitations are defined with respect to the adiabatic vacuum. We study the adiabaticity conditions and find that the dependence of our results on the choice of the order of the adiabatic vacuum increases with time. For large enough coupling particle production is so efficient that the Higgs decays to the true vacuum before this is an issue. However, for smaller values of the Higgs-curvature coupling no definite statements can be made as the vacuum dependence is large.Comment: 31 pages, 14 figure

Soil suppressiveness and functional diversity of the soil microflora in organic farming systems

Arable fields of 10 organic farms from different locations within the Netherlands were sampled in four subsequent years. The soil samples were analysed for disease suppressiveness against Rhizoctonia solani, Streptomyces scabies and Verticillium dahliae. Furthermore, a variety of microbial characteristics and chemical and physical soil properties were assessed. All these characteristics and different environmental factors were correlated by multivariate analyses. Significant differences in soil suppressiveness were found for all three diseases. Suppressiveness against Rhizoctonia was more or less consistent between the sampled fields in 2004 and 2005. This suppressiveness correlated with higher numbers of Lysobacter and Pseudomonas antagonists, as well as fungal diversity in DGGE patterns. Furthermore, results of 2006 showed that one year of grass-clover clearly stimulated Rhizoctonia suppression. Also Streptomyces soil suppressiveness was consistent between 2004 and 2005, but it concerned other soils than the ones which were suppressive against Rhizoctonia. Streptomyces suppression correlated with higher numbers of antagonists in general, Streptomyces and the fungal/bacterial biomass ratio, but with a lower organic matter content and respiration. Soil suppressiveness against Verticillium was not consistent between the years and therefore probably not related to soil factors

Top management team and board attributes and firm performance in the Netherlands

We survey the evidence on the relationship between board and top management team attributes and firm performance in the Netherlands (sample of 94 listed firms). To this aim we develop hypotheses by using sources from the strategic management and the corporate governance literature. Dutch corporations generally have a two-tier board system. We use the size of the top management team (TMT) and their average age as well as the size of the supervisory board (RVC) and the percentage of outside members as attributes of corporate performance. Our base model consists of two performance indicators: a composite financial accounting measure (of ROA, ROS, and ROE) and a market- based indicator (standardized stock prize increase). Control variables are: log of total assets as an indicator of the size of a firm, leverage and adjusted cash flow/total assets as indicators of financial structure, coefficients of variation of sales and ROA as measures of environmental uncertainty (dynamics), and diversification as a measure of risk-spread. In general, we conclude for the year 1996, that by using the base model, direct linear and non-linear relationships between the TMT/board variables and performance are not existent. Also, the interaction effects with environmental dynamics as a moderating variable are tested. From this analysis it becomes evident that, although environmental uncertainty has a clear direct relationship with performance, it has no significance as a moderating variable. Only in one case the interaction with size of the board leads to a significant result. Indicating (instead of the hypothesized inverted U-shaped relationship) a U-shaped relationship between RVC and performance.