BRST approach to Lagrangian formulation of bosonic totally antisymmeric tensor fields in curved space

We apply the BRST approach, previously developed for higher spin field theories, to gauge invariant Lagrangian construction for antisymmetric massive and massless bosonic fields in arbitrary d-dimensional curved space. The obtained theories are reducible gauge models both in massless and massive cases and the order of reducibility grows with the value of the rank of the antisymmetric field. In both the cases the Lagrangians contain the sets of auxiliary fields and possess more rich gauge symmetry in comparison with standard Lagrangian formulation for the antisymmetric fields. This serves additional demonstration of universality of the BRST approach for Lagrangian constructions in various field models.Comment: 12 page

Proximity-induced superconductivity in graphene

We propose a way of making graphene superconductive by putting on it small superconductive islands which cover a tiny fraction of graphene area. We show that the critical temperature, T_c, can reach several Kelvins at the experimentally accessible range of parameters. At low temperatures, T<<T_c, and zero magnetic field, the density of states is characterized by a small gap E_g<T_c resulting from the collective proximity effect. Transverse magnetic field H_g(T) E_g is expected to destroy the spectral gap driving graphene layer to a kind of a superconductive glass state. Melting of the glass state into a metal occurs at a higher field H_{g2}(T).Comment: 4 pages, 3 figure

Helicobacter pylori roles in haematology disease pathogenesis

Helicobacter pylori is considered to be one of the significant reasons of formation of gastroduodenal pathology. Data on the role of H. pylori in the development of extragastric diseases are confirmed by a positive effect of eradication on peripheral blood changes. In spite of this fact both aspects are still not revealed. However, undoubtedly that H. pylori persistence on gastric epithelium creates conditions for chronic local and systematic inflammation. The aim of the sur- vey was the analysis of literary data about bacterial factors in the development of iron-, vitamin B12-deficiency anaemia and thrombocytopenic purpura included by the international consensus into the circle of evedences for diagnosis and treatment of H. pylori. Material and methods. There was accomplished search of literature sources with the help of data bases PubMed, CyberLeninka, eLibrary, Google Scholar. The results of our analysis specify mechanisms of cer- tain blood diseases pathogenesis in association with H. pylori. Multiple roles of virulent strains of pathogen in anaemia and thrombocytopenic purpura include: development of erosive and ulcerative lesions of mucosa, hypoacidity, chron- ic inflammation and autoimmune response. Data about these changes in haematological syndromes and independent eradication effects on blood parameters normalisation, are controversial. Н. pylori host iron competition theory has not been found convincing confirmation. Conclusions. It is necessary to study more deeply the connection of H. pylori and haematological diseases. The dietary research and application to maintain the mucous integrity and bacterial adhesion prevention are perspective

Critical disorder effects in Josephson-coupled quasi-one-dimensional superconductors

Effects of non-magnetic randomness on the critical temperature T_c and diamagnetism are studied in a class of quasi-one dimensional superconductors. The energy of Josephson-coupling between wires is considered to be random, which is typical for dirty organic superconductors. We show that this randomness destroys phase coherence between the wires and T_c vanishes discontinuously when the randomness reaches a critical value. The parallel and transverse components of the penetration depth are found to diverge at different critical temperatures T_c^{(1)} and T_c, which correspond to pair-breaking and phase-coherence breaking. The interplay between disorder and quantum phase fluctuations results in quantum critical behavior at T=0, manifesting itself as a superconducting-normal metal phase transition of first-order at a critical disorder strength.Comment: 4 pages, 2 figure

Keldysh action for disordered superconductors

Keldysh representation of the functional integral for the interacting electron system with disorder is used to derive microscopically an effective action for dirty superconductors. In the most general case this action is a functional of the 8 x 8 matrix Q(t,t') which depends on two time variables, and on the fluctuating order parameter field and electric potential. We show that this approach reproduces, without the use of the replica trick, the well-known result for the Coulomb-induced renormalization of the electron-electron coupling constant in the Cooper channel. Turning to the new results, we calculate the effects of the Coulomb interaction upon: i) the subgap Andreev conductance between superconductor and 2D dirty normal metal, and ii) the Josephson proximity coupling between superconductive islands via such a metal. These quantities are shown to be strongly suppressed by the Coulomb interaction at sufficiently low temperatures due to both zero-bias anomaly in the density of states and disorder-enhanced repulsion in the Cooper channel.Comment: RevTeX; 39 pages + 10 EPS figure

Modern approaches to pharmacotherapy of chronic gastritis

The definition of gastritis is based on the histological features of the gastric mucosa. This is not the erythema observed during gastroscopy, and there are no specific clinical manifestations or symptoms that determine it. The modern classification of gastritis is based on time (acute and chronic), histological features, anatomical distribution and the main pathological mechanisms. Acute gastritis will develop into chronic if left untreated. Helicobacter pylori (H. pylori) is the most common cause of gastritis worldwide. However, from 60 to 70% H. pylori-negative subjects with functional dyspepsia or non-erosive gastroesophageal reflux were also found to have gastritis. H. pylori-negative gastritis is considered when a person meets all four of these criteria: negative triple staining of biopsies of the gastric mucosa, no history of treatment of H. pylori. In these patients, the cause of gastritis may be associated with tobacco smoking, alcohol consumption and / or the use of nonsteroidal anti-inflammatory drugs (NSAIDs) or steroids. Other causes of gastritis include autoimmune gastritis associated with antibodies of serum anti-parietal and anti-internal factor; organisms other than H. pylori, such as Mycobacterium avium intracellulare, Herpes simplex and Cytomegalovirus; gastritis caused by acid reflux; Rare causes of gastritis include collagen gastritis, sarcoidosis, eosinophilic gastritis and lymphocytic gastritis. The clinical picture, laboratory studies, gastroscopy, as well as histological and microbiological examination of tissue biopsies are important for the diagnosis of gastritis and its causes. Treatment of gastritis caused by H. pylori leads to the rapid disappearance of polymorphic-nuclear infiltration and a decrease in chronic inflammatory infiltrate with gradual normalization of the mucous membrane. Other types of gastritis should be treated based on their etiology

Mesoscopic fluctuations of the supercurrent in diffusive Josephson junctions

We study mesoscopic fluctuations and weak localization correction to the supercurrent in Josephson junctions with coherent diffusive electron dynamics in the normal part. Two kinds of junctions are considered: a chaotic dot coupled to superconductors by tunnel barriers and a diffusive junction with transparent normal--superconducting interfaces. The amplitude of current fluctuations and the weak localization correction to the average current are calculated as functions of the ratio between the superconducting gap and the electron dwell energy, temperature, and superconducting phase difference across the junction. Technically, fluctuations on top of the spatially inhomogeneous proximity effect in the normal region are described by the replicated version of the \sigma-model. For the case of diffusive junctions with transparent interfaces, the magnitude of mesoscopic fluctuations of the critical current appears to be nearly 3 times larger than the prediction of the previous theory which did not take the proximity effect into account.Comment: 19 pages, 14 figures, 2 table

6d conformal gravity

In the framework of ordinary-derivative approach, conformal gravity in space-time of dimension six is studied. The field content, in addition to conformal graviton field, includes two auxiliary rank-2 symmetric tensor fields, two Stueckelberg vector fields and one Stueckelberg scalar field. Gauge invariant Lagrangian with conventional kinetic terms and the corresponding gauge transformations are obtained. One of the rank-2 tensor fields and the scalar field have canonical conformal dimension. With respect to these fields, the Lagrangian contains, in addition to other terms, a cubic potential. Gauging away the Stueckelberg fields and excluding the auxiliary fields via equations of motion, the higher-derivative Lagrangian of 6d conformal gravity is obtained. The higher derivative Lagrangian involves quadratic and cubic curvature terms. This higher-derivative Lagrangian coincides with the simplest Weyl invariant density discussed in the earlier literature. Generalization of de Donder gauge conditions to 6d conformal fields is also obtained.Comment: 31 pages, LaTeX-2e, v3: Footnotes 8,9,13, clarifying remark below Eq.(2.30), and references added. Misprints correcte