Auxiliary matrices for the six-vertex model at roots of 1 and a geometric interpretation of its symmetries

The construction of auxiliary matrices for the six-vertex model at a root of unity is investigated from a quantum group theoretic point of view. Employing the concept of intertwiners associated with the quantum loop algebra $U_q(\tilde{sl}_2)$ at $q^N=1$ a three parameter family of auxiliary matrices is constructed. The elements of this family satisfy a functional relation with the transfer matrix allowing one to solve the eigenvalue problem of the model and to derive the Bethe ansatz equations. This functional relation is obtained from the decomposition of a tensor product of evaluation representations and involves auxiliary matrices with different parameters. Because of this dependence on additional parameters the auxiliary matrices break in general the finite symmetries of the six-vertex model, such as spin-reversal or spin conservation. More importantly, they also lift the extra degeneracies of the transfer matrix due to the loop symmetry present at rational coupling values. The extra parameters in the auxiliary matrices are shown to be directly related to the elements in the enlarged center of the quantum loop algebra $U_q(\tilde{sl}_2)$ at $q^N=1$. This connection provides a geometric interpretation of the enhanced symmetry of the six-vertex model at rational coupling. The parameters labelling the auxiliary matrices can be interpreted as coordinates on a three-dimensional complex hypersurface which remains invariant under the action of an infinite-dimensional group of analytic transformations, called the quantum coadjoint action.Comment: 52 pages, TCI LaTex, v2: equation (167) corrected, two references adde

Gauge transformations and symmetries of integrable systems

We analyze several integrable systems in zero-curvature form within the framework of $SL(2,\R)$ invariant gauge theory. In the Drienfeld-Sokolov gauge we derive a two-parameter family of nonlinear evolution equations which as special cases include the Kortweg-de Vries (KdV) and Harry Dym equations. We find residual gauge transformations which lead to infinintesimal symmetries of this family of equations. For KdV and Harry Dym equations we find an infinite hierarchy of such symmetry transformations, and we investigate their relation with local conservation laws, constants of the motion and the bi-Hamiltonian structure of the equations. Applying successive gauge transformatinos of Miura type we obtain a sequence of gauge equivalent integrable systems, among them the modified KdV and Calogero KdV equations.Comment: 18pages, no figure Journal versio

Growth hormone deficiency in childhood brain tumors and acute lymphoblastic leukemia survivors

Thanks to modern treatment protocols, childhood cancer survivors (CCS) are a very fast-growing population nowadays. Cancer therapy inevitably leads to different late adverse effects, where endocrine disorders are highly prevalent, including growth hormone deficiency (GHD) which is the most common endocrine outcome after cancer treatment in childhood and contributes to impaired growth. Short stature is a big issue, which leads to problems in psychological and social adaptation of patients and reduces their quality of life. Impact of GH treatment on various physiological processes and global outcome of CCS is of great interest. Several studies have demonstrated an influence of GH and IGF-1 on the development/tumour growth, cell proliferation. In this regard, the issue of increasing the risk of cancer recurrence and/or the development of secondary neoplasms in CCS, causes a lot of controversy and is the subject of continuous evaluation. In this review, we went through the available data on the prevalence and pathogenesis of GHD following chemo- and radiotherapy, in particular after treatment of brain tumors and acute lymphoblastic leukaemia in childhood. In addition, here we discuss the existing problems in the diagnosis of GHD, the safety of GH replacement therapy, as well as the treatment algorithm of the GHD in adults

Thermodynamics of quantum Heisenberg spin chains

Thermodynamic properties of the quantum Heisenberg spin chains with S = 1/2, 1, and 3/2 are investigated using the transfer-matrix renormalization-group method. The temperature dependence of the magnetization, susceptibility, specific heat, spin-spin correlation length, and several other physical quantities in a zero or finite applied field are calculated and compared. Our data agree well with the Bethe ansatz, exact diagonalization, and quantum Monte Carlo results and provide further insight into the quantum effects in the antiferromagnetic Heisenberg spin chains.Comment: 9 pages, 10 figure

The Path Integral Quantization And The Construction Of The S-matrix In The Abelian And Non-Abelian Chern-Simons Theories

The cvariant path integral quantization of the theory of the scalar and spinor particles interacting through the abelian and non-Abelian Chern-Simons gauge fields is carried out and is shown to be mathematically ill defined due to the absence of the transverse components of these gauge fields. This is remedied by the introduction of the Maxwell or the Maxwell-type (in the non-Abelian case)term which makes the theory superrenormalizable and guarantees its gauge-invariant regularization and renormalization. The generating functionals are constructed and shown to be formally the same as those of QED (or QCD) in 2+1 dimensions with the substitution of the Chern-Simons propagator for the photon (gluon) propagator. By constructing the propagator in the general case, the existence of two limits; pure Chern-Simons and QED (QCD) after renormalization is demonstrated. By carrying out carefully the path integral quantization of the non-Abelian Chern-Simons theories using the De Witt-Fadeev-Popov and the Batalin-Fradkin- Vilkovisky methods it is demonstrated that there is no need to quantize the dimensionless charge of the theory. The main reason is that the action in the exponent of the path integral is BRST-invariant which acquires a zero winding number and guarantees the BRST renormalizability of the model. The S-matrix operator is constructed, and starting from this S-matrix operator novel topological unitarity identities are derived that demand the vanishing of the gauge-invariant sum of the imaginary parts of the Feynman diagrams with a given number of intermediate on-shell topological photon lines in each order of perturbation theory. These identities are illustrated by an explicit example.Comment: LaTex file, 31 pages, two figure

Two years of experience in hospital surveillance for the severe influenza like illnesses in St. Petersburg: etiology, clinical characterization of diseases, antigenic and genetic properties of isolated influenza viruses

In this paper, we analyze the etiology of the diseases occurring during two consecutive influenza epidemic seasons in St. Petersburg, Russian Federation. The analysis is based on the results of the PCR diagnostics of the clinical samples collected from patients hospitalized in three St. Petersburg hospitals with influenza like illnesses (ILI). It was shown that the influenza virus A(H1N1)pdm09 was the dominant causative agent during the 2012-2013 epidemic season while, in the 2013-2014 season, A(H3N2) virus was predominant among adults and children. The influenza B virus activity was high in the 2012-2013 season and low in the 2013-2014 season. During both seasons, the main causative agent for the hospitalization of young children was respiratory syncytial virus (RSV), followed by rhinovirus and influenza virus. The rate of involvement of parainfluenza, adenovirus, metapneumovirus and coronavirus was low and was negligible for bocavirus. Children 0-2 and 3-6 years old formed the group of patients that was affected by acute respiratory infection agents the most. Children younger than 3 months old were the major group of the intensive care unit (ICUs) patients and only 27.5% of them were adults. RSV and rhinovirus were the leading cause of ILI among the children admitted to ICU. Among the adult patients admitted to the ICU, only influenza A(H1N1)pdm09, A(H3N2) and B viruses were detected during both influenza seasons.According to the results of the antigenic and genetic analysis, most influenza A(H1N1)pdm09 and A(H3N2) viruses circulating in St. Petersburg matched the vaccine strains recommended by the WHO for vaccine composition in the 2012-2013 and 2013-2014 seasons.In this paper, we analyze the etiology of the diseases occurring during two consecutive influenza epidemic seasons in St. Petersburg, Russian Federation. The analysis is based on the results of the PCR diagnostics of the clinical samples collected from patients hospitalized in three St. Petersburg hospitals with influenza like illnesses (ILI). It was shown that the influenza virus A(H1N1)pdm09 was the dominant causative agent during the 2012-2013 epidemic season while, in the 2013-2014 season, A(H3N2) virus was predominant among adults and children. The influenza B virus activity was high in the 2012-2013 season and low in the 2013-2014 season. During both seasons, the main causative agent for the hospitalization of young children was respiratory syncytial virus (RSV), followed by rhinovirus and influenza virus. The rate of involvement of parainfluenza, adenovirus, metapneumovirus and coronavirus was low and was negligible for bocavirus. Children 0-2 and 3-6 years old formed the group of patients that was affected by acute respiratory infection agents the most. Children younger than 3 months old were the major group of the intensive care unit (ICUs) patients and only 27.5% of them were adults. RSV and rhinovirus were the leading cause of ILI among the children admitted to ICU. Among the adult patients admitted to the ICU, only influenza A(H1N1)pdm09, A(H3N2) and B viruses were detected during both influenza seasons. According to the results of the antigenic and genetic analysis, most influenza A(H1N1)pdm09 and A(H3N2) viruses circulating in St. Petersburg matched the vaccine strains recommended by the WHO for vaccine composition in the 2012-2013 and 2013-2014 seasons

Etiology of influenza-like illnesses in the population of Novosibirsk city in the 2018–2019 epidemic season

Influenza and other acute respiratory viral infections lead to a substantial incidence of severe cases and hospitalizations and so remain a global health problem. Within the frame of the Global Influenza Hospital Surveillance Network (GIHSN), we assessed the contribution of influenza and other respiratory viruses to severe cases of influenzalike diseases in patients hospitalized to the Novosibirsk infectious hospitals in the years 2018–2019. We analyzed 484 nasopharyngeal swabs collected from patients admitted to the hospitals with acute respiratory infections (ARI) using real-time polymerase chain reaction commercial kits. We confirmed viral etiology of ARI in 69.8% cases. Influenza viruses were detected in 47.1% cases, wherein concomitant circulation of influenza A(H1N1)pdm09 and A(H3N2) viruses was observed in 20.7% and 26% of patients, respectively, whereas influenza B virus was detected only in one sample. All analyzed influenza A viruses were antigenically similar to vaccine strains. Genetically, the Novosibirsk strains were closely related to influenza A viruses distributed in Russia and worldwide. Influenza A(H1N1)pdm09 virus was detected in all patients aged 0 to 14 years and required intensive care. Other respiratory viruses were detected in 36.4% of children and 5.8% of adults, and 8.3% of children had viral coinfection, whereas no cases of coinfection were detected in adults. The most common viruses in children were metapneumovirus — 12.8%, rhinovirus — 9.3% and respiratory syncytial virus — 8.0%. In adults, metapneumovirus, adenovirus, parainfluenza virus and rhinovirus were detected with a detection rate no exceeding 2%. In this study, we found no differences in the detection rate of the influenza virus due to concomitant chronic diseases, pregnancy, or smoking habits. At the same time, the detection rate of other respiratory viruses in non-smokers vs. smokers was significantly lower than in smokers and former smokers (26.15%, 66.67% and 62.50%, respectively). In addition, the level of detection of respiratory viruses in children with vs. without chronic pathology was significantly higher (55.3% and 38.7%, respectively). Thus, our and similar studies are important for monitoring and control of the infection

Canagliflozin: from glycemic control to improvement of cardiovascular and renal prognosis in patients with type 2 diabetes mellitus. Resolution of Advisory Board

Inhibitors of the sodium-glucose cotransporter type 2 (SGLT2i) are a modern class of antihyperglycemic drugs with an insulin-independent mechanism of action. Due to its ability to effectively lower blood glucose levels, improve a number of other cardiometabolic parameters (body weight, blood pressure, uric acid), as well as reduce cardiovascular and renal risks, SGLT2i have become drugs of choice for many of patients with type 2 diabetes mellitus (T2DM). Meanwhile, along with the generally recognized classes-effects of this group of drugs, there are intragroup features, including those associated with their different selectivity in sodium-glucose cotransporters of types 1 and 2 (SGLT1 and SGLT 2). For example, one of the most studied SGLT2i, canagliflozin, in addition to its inhibitory activity against SGLT2, can also moderately block SGLT1 in the intestine and kidneys that could give a maximum efficiency in the control glycemia and others cardiometabolic parameters. In addition, canagliflozin improves not only cardiovascular, but also renal prognosis in patients with T2DM, which is reflected in the corresponding indications in the summary of product characteristics of the drug. This document summarize the established and new data regarding the efficacy and safety of canagliflozin, as well as its place in the treatment of T2DM