Lorentz Violation and Synchrotron Radiation

We consider the radiation emitted by an ultrarelativistic charged particle moving in a magnetic field, in the presence of an additional Lorentz-violating interaction. In contrast with prior work, we treat a form of Lorentz violation that is represented by a renormalizable operator. Neglecting the radiative reaction force, the particle's trajectory can be determined exactly. The resulting orbit is generally noncircular and does not lie in the place perpendicular to the magnetic field. We do not consider any Lorentz violation in the electromagnetic sector, so the radiation from the accelerated charge can be determined by standard means, and the radiation spectrum will exhibit a Lorentz-violating directional dependence. Using data on emission from the Crab nebula, we can set a bound on a particular combination of Lorentz-violating coefficients at the $6\times10^{-20}$ level.Comment: 14 page

Intraspecific and interstage similarities in host-plant preference in the diamondback moth (Lepidoptera: Plutellidae)

The diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), is an important insect pest of cruciferous crops. Understanding its preference patterns can lead to more efficient management methods, such as trap crops. Several strains of P. xylostella were used to test whether there were differences in oviposition preference in a four-choice setting, on abaxial versus adaxial leaf surfaces in 28 different plant species, and on substrates with different concentrations of sinigrin (allylglucosinolate). Additionally, the larval preference of P. xylostella was studied with 17 plant species of known glucosinolate content that were compared to Arabidopsis thaliana L. in two-choice tests. Our research shows that the diet on which P. xylostella has fed hardly affects multiple-choice host-plant preference, abaxial and adaxial oviposition preference, or oviposition response to pure glucosinolates. Our study also shows that glucosinolate content affects larval preference, which together with the known correlation between glucosinolate content and P. xylostella oviposition, indicates that crops with high glucosinolate content could be more susceptible to damage by P. xylostella than crops with low glucosinolate content. These findings are discussed in regards to their significance in the management of P. xylostella

Coevolutionary fine-tuning: evidence for genetic tracking between a specialist wasp parasitoid and its aphid host in a dual metapopulation interaction

In the interaction between two ecologically-associated species, the population structure of one species may affect the population structure of the other. Here, we examine the population structures of the aphid Metopeurum fuscoviride, a specialist on tansy Tanacetum vulgare, and its specialist primary hymenopterous parasitoid Lysiphlebus hirticornis, both of which are characterized by multivoltine life histories and a classic metapopulation structure. Samples of the aphid host and the parasitoid were collected from eight sites in and around Jena, Germany, where both insect species co-occur, and then were genotyped using suites of polymorphic microsatellite markers. The host aphid was greatly differentiated in terms of its spatial population genetic patterning, while the parasitoid was, in comparison, only moderately differentiated. There was a positive Mantel test correlation between pairwise shared allele distance (DAS) of the host and parasitoid, i.e. if host subpopulation samples were more similar between two particular sites, so were the parasitoid subpopulation samples. We argue that while the differences in the levels of genetic differentiation are due to the differences in the biology of the species, the correlations between host and parasitoid are indicative of dependence of the parasitoid population structure on that of its aphid host. The parasitoid is genetically tracking behind the aphid host, as can be expected in a classic metapopulation structure where host persistence depends on a delay between host and parasitoid colonization of the patch. The results may also have relevance to the Red Queen hypothesis, whereupon in the ‘arms race’ between parasitoid and its host, the latter ‘attempts’ to evolve away from the former

Editorial

Welcome to the second edition of the International Journal for Researcher Development. In this issue, we are pleased to include an in-depth study on the professionality of researchers per se. In her article, ‘Developing research capacity in the social sciences: a professionality-based model’ Linda Evans draws attention to the importance of both developing a research culture and developing researchers themselves. She suggests that leadership in research is failing to achieve the development of institutional research capacity to an acceptable standard whilst researchers themselves are unaware of the necessity to develop continually. In our next article, Fowler and colleagues present evidence from a recent study as to the factors that are necessary to facilitate the building of research capacity in the UK. In their article, ‘Building research capacity across the UK: evidence from recent initiatives in England, Scotland and Wales’ they recommend more explicit institutional commitment to the professional development of research staff and suggest that this should include the facilitation of mentoring relationships between more and less experienced researchers. The paper by Pitcher and Akerlind provides an international slant by presenting results of a novel study using metaphor analysis across several Australian Universities. This enabled conceptions of research by researchers to be categorized. Finally, we include a report on discussions based around evaluating developmental activities for researchers in higher education. In the UK, Roberts funding came on-line in 2002 to support the development of skills training for post-graduate researchers – to assist their employability. That tranche of funding is nearing its end and universities across the UK are now having to evaluate the worth of the products of that funding and how to fund it, if at all, in the future. The Gough report on the discussions surrounding the development of an evaluation approach make interesting reading

Leveraging Semantic Web Service Descriptions for Validation by Automated Functional Testing

Recent years have seen the utilisation of Semantic Web Service descriptions for automating a wide range of service-related activities, with a primary focus on service discovery, composition, execution and mediation. An important area which so far has received less attention is service validation, whereby advertised services are proven to conform to required behavioural specifications. This paper proposes a method for validation of service-oriented systems through automated functional testing. The method leverages ontology-based and rule-based descriptions of service inputs, outputs, preconditions and effects (IOPE) for constructing a stateful EFSM specification. The specification is subsequently utilised for functional testing and validation using the proven Stream X-machine (SXM) testing methodology. Complete functional test sets are generated automatically at an abstract level and are then applied to concrete Web services, using test drivers created from the Web service descriptions. The testing method comes with completeness guarantees and provides a strong method for validating the behaviour of Web services

Bound on Lorentz- and CPT-Violating Boost Effects for the Neutron

A search for an annual variation of a daily sidereal modulation of the frequency difference between co-located ${}^{129}$Xe and ${}^{3}$He Zeeman masers sets a stringent limit on boost-dependent Lorentz and CPT violation involving the neutron, consistent with no effect at the level of 150 nHz. In the framework of the general Standard-Model Extension, the present result provides the first clean test for the fermion sector of the symmetry of spacetime under boost transformations at a level of $10^{-27}$ GeV.Comment: 4 pages, 1 figur

Sparse Randomized Kaczmarz for Support Recovery of Jointly Sparse Corrupted Multiple Measurement Vectors

While single measurement vector (SMV) models have been widely studied in signal processing, there is a surging interest in addressing the multiple measurement vectors (MMV) problem. In the MMV setting, more than one measurement vector is available and the multiple signals to be recovered share some commonalities such as a common support. Applications in which MMV is a naturally occurring phenomenon include online streaming, medical imaging, and video recovery. This work presents a stochastic iterative algorithm for the support recovery of jointly sparse corrupted MMV. We present a variant of the Sparse Randomized Kaczmarz algorithm for corrupted MMV and compare our proposed method with an existing Kaczmarz type algorithm for MMV problems. We also showcase the usefulness of our approach in the online (streaming) setting and provide empirical evidence that suggests the robustness of the proposed method to the distribution of the corruption and the number of corruptions occurring.Comment: 13 pages, 6 figure

MAX-DOAS measurements of formaldehyde in the Po-Valley

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Harmonic Analysis of Boolean Networks: Determinative Power and Perturbations

Consider a large Boolean network with a feed forward structure. Given a probability distribution on the inputs, can one find, possibly small, collections of input nodes that determine the states of most other nodes in the network? To answer this question, a notion that quantifies the determinative power of an input over the states of the nodes in the network is needed. We argue that the mutual information (MI) between a given subset of the inputs X = {X_1, ..., X_n} of some node i and its associated function f_i(X) quantifies the determinative power of this set of inputs over node i. We compare the determinative power of a set of inputs to the sensitivity to perturbations to these inputs, and find that, maybe surprisingly, an input that has large sensitivity to perturbations does not necessarily have large determinative power. However, for unate functions, which play an important role in genetic regulatory networks, we find a direct relation between MI and sensitivity to perturbations. As an application of our results, we analyze the large-scale regulatory network of Escherichia coli. We identify the most determinative nodes and show that a small subset of those reduces the overall uncertainty of the network state significantly. Furthermore, the network is found to be tolerant to perturbations of its inputs