Recursive Graphical Construction of Feynman Diagrams in phi^4 Theory: Asymmetric Case and Effective Energy

The free energy of a multi-component scalar field theory is considered as a functional W[G,J] of the free correlation function G and an external current J. It obeys non-linear functional differential equations which are turned into recursion relations for the connected Greens functions in a loop expansion. These relations amount to a simple proof that W[G,J] generates only connected graphs and can be used to find all such graphs with their combinatoric weights. A Legendre transformation with respect to the external current converts the functional differential equations for the free energy into those for the effective energy Gamma[G,Phi], which is considered as a functional of the free correlation function G and the field expectation Phi. These equations are turned into recursion relations for the one-particle irreducible Greens functions. These relations amount to a simple proof that Gamma[G,J] generates only one-particle irreducible graphs and can be used to find all such graphs with their combinatoric weights. The techniques used also allow for a systematic investigation into resummations of classes of graphs. Examples are given for resumming one-loop and multi-loop tadpoles, both through all orders of perturbation theory. Since the functional differential equations derived are non-perturbative, they constitute also a convenient starting point for other expansions than those in numbers of loops or powers of coupling constants. We work with general interactions through four powers in the field.Comment: 34 pages; abstract expanded; section IV.E about absorption of tadpoles and one related reference added; eqs. (20) and (23) corrected; further references added; some minor beautifications; to be published by Phys.Rev.

Spontaneous symmetry breaking and the p→0p \to 0 limit

We point out a basic ambiguity in the $p \to 0$ limit of the connected propagator in a spontaneously broken phase. This may represent an indication that the conventional singlet Higgs boson, rather than being a purely massive field, might have a gap-less branch. This would dominate the energy spectrum for ${\bf{p}} \to 0$ and give rise to a very weak, long-range force. The natural interpretation is in terms of density fluctuations of the `Higgs condensate': in the region of very long wavelengths, infinitely larger than the Fermi scale, it cannot be treated as a purely classical c-number field.Comment: 17 pages, LaTex, small changes and some comments adde

Competing energy scales in topological superconducting heterostructures

Artificially engineered topological superconductivity has emerged as a viable route to create Majorana modes. In this context, proximity-induced super-conductivity in materials with a sizable spin-orbit coupling has been intensively investigated in recent years. Although there is convincing evidence that superconductivity may indeed be induced, it has been difficult to elucidate its topological nature. Here, we engineer an artificial topological superconductor by progressively introducing superconductivity (Nb), strong spin-orbital coupling (Pt), and topological states (Bi2Te3). Through spectroscopic imaging of superconducting vortices within the bare s-wave superconducting Nb and within proximitized Pt and Bi2Te3 layers, we detect the emergence of a zero-bias peak that is directly linked to the presence of topological surface states. Our results are rationalized in terms of competing energy trends which are found to impose an upper limit to the size of the minigap separating Majorana and trivial modes, its size being ultimately linked to fundamental materials properties

A logical approach for behavioural composition of scenario-based models

As modern systems become more complex, design approaches model different aspects of the system separately. When considering (intra and inter) system interactions, it is usual to model individual scenarios using UML’s sequence diagrams. Given a set of scenarios we then need to check whether these are consistent and can be combined for a better understanding of the overall behaviour. This paper addresses this by presenting a novel formal technique for composing behavioural models at the metamodel level through exact metamodel restriction (EMR). In our approach a sequence diagram can be completely described by a set of logical constraints at the metamodel level. When composing sequence diagrams we take the union of the sets of logical constraints for each diagram and additional behavioural constraints that describe the matching composition glue. A formal semantics for composition in accordance with the glue guides our model transformation to Alloy. Alloy’s fully automated constraint solver gives us the solution. Our technique has been implemented as an Eclipse plugin SD2Alloy.Postprin

Совершенствование технологического процесса изготовления детали «Корпус»

Совершенствование технологического процесса изготовления детали «Корпус». Технологический раздел, Конструкторский раздел, Технико-экономическое обоснование ,Социальная ответственность.Perfection of technological process of manufacturing parts "Housing". Technological section, design section, Feasibility Study, Social Responsibility

Correct composition of dephased behavioural models

This research is supported by EPSRC grant EP/M014290/1.Scenarios of execution are commonly used to specify partial behaviour and interactions between different objects and components in a system. To avoid overall inconsistency in specifications, various automated methods have emerged in the literature to compose (behavioural) models. In recent work, we have shown how the theorem prover Isabelle can be combined with the constraint solver Z3 to efficiently detect inconsistencies in two or more behavioural models and, in their absence, generate the composition. Here, we extend our approach further and show how to generate the correct composition (as a set of valid traces) of dephased models. This work has been inspired by a problem from a medical domain where different care pathways (for chronic conditions) may be applied to the same patient with different starting points.Postprin

Evaluation of vaccine delivery systems for inducing long-lived antibody responses to Dermanyssus gallinae antigen in laying hens

Dermanyssus gallinae, the poultry red mite, is a global threat to the commercial egg-laying industry. Control of D. gallinae is difficult, with only a limited number of effective pesticides and non-chemical treatments available. Here we characterise the candidate vaccine antigen D. gallinae cathepsin D-1 (Dg-CatD-1) and demonstrate that purified refolded recombinant Dg-Cat-D1 (rDg-CatD-1) is an active aspartyl proteinase which digests haemoglobin with a pH optimum of pH 4. Soluble protein extracts from D. gallinae also have haemoglobinase activity, with a pH optimum comparable to the recombinant protein and both proteinase activities were inhibited by the aspartyl proteinase inhibitor Pepstatin A. Enzyme activity and the ubiquitous localization of Dg-CatD-1 protein in sections of adult female mites is consistent with Dg-CatD-1 being a lysosomal proteinase. Using Dg-CatD-1 as a model vaccine antigen, we compared vaccine delivery methods in laying hens via vaccination with: i) purified rDg-CatD-1 with Montanide™ ISA 71 VG adjuvant; ii) recombinant DNA vaccines for expression of rDg-CatD-1 and iii) transgenic coccidial parasite Eimeria tenella expressing rDg-CatD-1. In two independent trials, only birds vaccinated with rDg-CatD-1 with Montanide™ ISA 71 VG produced a strong and long-lasting serum anti-rDg-Cat-D1 IgY response, which was significantly higher than control birds vaccinated with adjuvant only. Furthermore, we showed that egg laying rates of D. gallinae mites fed on birds vaccinated with rDg-CatD-1 in Montanide™ ISA 71 VG was reduced significantly compared with mites fed on unvaccinated birds

Measurement of e⁺e⁻-->e⁺e⁻ and e⁺e⁻-->gammagamma at energies up to 36.7 GeV

e+e- +- +- ... + e e und e e + yy wurden bel Energlen zwischen 33.0 und 36.7 GeV gemessen. Die Ergebnisse stimmen mit den Vorhersagen der Quantenelektrodynamik überein. Ein Vergleich mit dem Standardmodell der elektroschwachen Wechselwirkung liefert sin 20w= 0.25 ± 0.13

MediPlEx - a tool to combine in silico & experimental gene expression profiles of the model legume Medicago truncatula

Henckel K, Küster H, Stutz L, Goesmann A. MediPlEx - a tool to combine in silico and experimental gene expression profiles of the model legume Medicago truncatula. BMC Research Notes. 2010;3(1): 262.BACKGROUND:Expressed Sequence Tags (ESTs) are in general used to gain a first insight into gene activities from a species of interest. Subsequently, and typically based on a combination of EST and genome sequences, microarray-based expression analyses are performed for a variety of conditions. In some cases, a multitude of EST and microarray experiments are conducted for one species, covering different tissues, cell states, and cell types. Under these circumstances, the challenge arises to combine results derived from the different expression profiling strategies, with the goal to uncover novel information on the basis of the integrated datasets.FINDINGS:Using our new application, MediPlEx (MEDIcago truncatula multiPLe EXpression analysis), expression data from EST experiments, oligonucleotide microarrays and Affymetrix GeneChips can be combined and analyzed, leading to a novel approach to integrated transcriptome analysis. We have validated our tool via the identification of a set of well-characterized AM-specific and AM-induced marker genes, identified by MediPlEx on the basis of in silico and experimental gene expression profiles from roots colonized with AM fungi.CONCLUSIONS:MediPlEx offers an integrated analysis pipeline for different sets of expression data generated for the model legume Medicago truncatula. As expected, in silico and experimental gene expression data that cover the same biological condition correlate well. The collection of differentially expressed genes identified via MediPlEx provides a starting point for functional studies in plant mutants. MediPlEx can freely be used at http://www.cebitec.uni-bielefeld.de/mediplex