Muon pair creation from positronium in a circularly polarized laser field

We study elementary particle reactions that result from the interaction of an atomic system with a very intense laser wave of circular polarization. As a specific example, we calculate the rate for the laser-driven reaction $e^+e^- \to \mu^+\mu^-$, where the electron and positron originate from a positronium atom or, alternatively, from a nonrelativistic $e^+e^-$ plasma. We distinguish accordingly between the coherent and incoherent channels of the process. Apart from numerical calculations, we derive by analytical means compact formulas for the corresponding reaction rates. The rate for the coherent channel in a laser field of circular polarization is shown to be damped because of the destructive interference of the partial waves that constitute the positronium ground-state wave packet. Conditions for the observation of the process via the dominant incoherent channel in a circularly polarized field are pointed out

Macrophage polarization in sarcoidosis

Sarcoidosis is a systemic inflammatory disease of unknown etiology, characterized by the formation of epithelioid cell granulomas, multisystem lesions with a certain frequency of involvement of various organs, mainly the lungs (up to 90% of cases). Over the past decade, significant progress has been made in understanding the pathogenesis of sarcoidosis, the important role of immunological, genetic and environmental factors in the development of this pathology has been established. It is believed that the leading mechanism in the pathogenesis of sarcoidosis is the aberrant activation of the innate and adaptive immune response to unidentified antigen(s), which leads to the development of granulomatous inflammation and the formation of granulomas. However, despite the huge number of studies that has been carried out, the mechanisms and signaling pathways that control the development of the inflammatory process during the formation of granulomas and the progression of pathology have not been fully determined.This literature review examines the important role of various cytokines and T helper subpopulations in sarcoidosis. Particular attention is paid to the cells of innate immunity – macrophages in the pathogenesis of this disease. These cells play a key role in the formation of sarcoid granulomas and in the pathogenesis of sarcoidosis. The macrophage population is characterized by plasticity and functional heterogeneity. In response to various signals from the microenvironment, macrophages are able to acquire certain phenotypes. The review considers the issues of polarization of macrophages, changes in the phenotype of these cells to subpopulations M1 (M1 phenotype; classically activated; pro-inflammatory) and M2 (M2 phenotype; alternatively activated, anti-inflammatory). These two cell populations are characterized by the expression of different markers on their surface, which allow these cells to differentiate from each other. The analysis of literature data on the levels of key polarizing cytokines for macrophages and cells-producers of these cytokines that patients with sarcoidosis have, in acute and chronic course of the disease, was carried out.Important aspects of the alternative activation of macrophages of the M2 phenotype and their division into subtypes: M2a, M2b, M2c, M2d are noted. The features of various subtypes’ activation of macrophages in this granulomatosis and their importance in the development and progression of pathology are considered. Studying the role of macrophages’ phenotypes, understanding the mechanisms by which the phenotypes of these cells are activated and modulated in various microenvironmental conditions, can contribute to the development and implementation into clinical practice of new therapeutic approaches for the treatment of sarcoidosis and many other forms of pathologies

A New Chapter in the Treatment of Patients with Heart Failure. The Role of Sodium-Glucose Co-transporter Type 2 Inhibitors

Heart failure (HF) remains one of the major social and medical public health problems worldwide. Despite new advances in the treatment of patients with HF, the prognosis is still poor. According to the European Cardiology Society guidelines for the diagnosis and treatment of acute and chronic heart failure (CHF) 2021, a new class of drugs related to hypoglycemic has been confirmed to be effective in influencing the survival of patients with heart failure with low ejection fraction (HFpEF), regardless of the presence of disorders of carbohydrate metabolism. We are talking about inhibitors of the sodium-glucose co-transporter type 2 (iSGLT-2) or gliflozins. The article presents the results of the latest large clinical trials on the effective use of SGLT-2 in patients with HF, not only with low, but also with intact ejection fraction (HFpEF), for which there is no evidence base at the present stage. The review article presents the results of experimental studies that explored the potential mechanisms of action of gliflozins with an emphasis on new ones that are of fundamental importance for patients with heart failure, and also describes controversial and little-studied issues. Currently, there is no therapy that improves outcomes in patients with acute heart failure. The article presents the results of small analyzes of the use of iSGLT-2 in this category of patients, which are the basis for the hypothesis of their potentially effective and safe use in the case of acute decompensation of CHF, however, the role of gliflozins in this category of patients requires further in-depth study

Clinical Efficacy and Safety of Empagliflozin in Patients with Acute Heart Failure from the First Day of Hospitalization

Aim. Evaluation of the safety, clinical and hemodynamic effects of empagliflozin in patients with acute decompensated heart failure (ADHF) from the first day of hospitalization in the absence of signs of hemodynamic instability.Material and methods. A prospective, comparative, randomized study included 46 patients admitted to the hospital in connection with ADHF in the absence of signs of hemodynamic instability. Inclusion in the study and randomization to receive empagliflozin was carried out in the first 24 hours from the moment of admission to the hospital. The main group (n=23) from the first day of hospitalization and the entire subsequent follow-up period took empagliflozin at a daily dose of 10 and 25 mg (for patients with type 2 diabetes mellitus) in addition to basic therapy, the control group (n=23) received standard therapy without gliflozines. The observation period was 3 months and included 3 control points: 1st day of hospitalization, 7th-12th day, 3rd month of observation. Clinical, anamnestic and instrumental data were evaluated at all control points.Results. In the hospital period, by the 7th-12th day, only in the main group there was an improvement in all clinical indicators (p<0.01), an increase in the rate of diuresis (p><0.01), a decrease in the daily dose of the parenteral diuretic furosemide from 54 mg to 26 mg (p><0.01). A decrease in systolic blood pressure (SBP) occurred in both groups (p><0.01), but it was more pronounced in the comparison group [from 141 (110; 160) to 110 (90; 120) mm Hg) compared to the main group [from 140 (120; 160) to 120 (110; 130) mm Hg]. According to echocardiography data in the main group, there was a decrease in the indexed volume of the right atrium, the end-systolic volume of the left ventricle (LV ESV) and systolic pressure in the pulmonary artery, an increase in the LV ejection fraction (LV EF) (p><0.05). In the comparison group, only an increase in LV ESV was noted (p=0.04). The index of the indexed volume of the left atrium did not show significant dynamics in the main group (p=0.79), but showed a significant decrease>˂0.01), a decrease in the daily dose of the parenteral diuretic furosemide from 54 mg to 26 mg (p<0.01). A decrease in systolic blood pressure (SBP) occurred in both groups (p>˂0.01), but it was more pronounced in the comparison group [from 141 (110; 160) to 110 (90; 120) mm Hg) compared to the main group [from 140 (120; 160) to 120 (110; 130) mm Hg]. According to echocardiography data in the main group, there was a decrease in the indexed volume of the right atrium, the end-systolic volume of the left ventricle (LV ESV) and systolic pressure in the pulmonary artery, an increase in the LV ejection fraction (LV EF) (p˂0.05). In the comparison group, only an increase in LV ESV was noted (p=0.04). The index of the indexed volume of the left atrium did not show significant dynamics in the main group (p=0.79), but showed a significant decrease in the 2nd and 3rd control points compared to the control group (p=0.01 and p=0.02). Complications, against the background of taking empagliflozin, were not noted: there were no episodes of hypotension (SBP˂90 mm Hg), hypoglycemia, acute kidney injury.Conclusion. The results obtained indicate the safety of empagliflozin in patients with ADHF, regardless of the status of carbohydrate metabolism and LV EF, as well as taking into account the clinical (more intense positive dynamics of clinical symptoms of ADHF) and hemodynamic (smooth decrease in SBP, increased diuretic effect) effects of empagliflozin, this drug should be considered as an effective and safe supplement to the main therapy from the first day of hospitalization in patients with stable hemodynamic parameters

Observation of narrow baryon resonance decaying into pKs0pK^0_s in pA-interactions at 70GeV/c70 GeV/c with SVD-2 setup

SVD-2 experiment data have been analyzed to search for an exotic baryon state, the $\Theta^+$-baryon, in a $pK^0_s$ decay mode at $70 GeV/c$ on IHEP accelerator. The reaction $pA \to pK^0_s+X$ with a limited multiplicity was used in the analysis. The $pK^0_s$ invariant mass spectrum shows a resonant structure with $M=1526\pm3(stat.)\pm 3(syst.) MeV/c^2$ and $\Gamma < 24 MeV/c^2$. The statistical significance of this peak was estimated to be of $5.6 \sigma$. The mass and width of the resonance is compatible with the recently reported $\Theta^+$- baryon with positive strangeness which was predicted as an exotic pentaquark ($uudd\bar{s}$) baryon state. The total cross section for $\Theta^+$ production in pN-interactions for $X_F\ge 0$ was estimated to be $(30\div120) \mu b$ and no essential deviation from A-dependence for inelastic events $(\sim A^{0.7})$ was found.Comment: 8 pages, 7 figures, To be submitted to Yadernaya Fizika. v3-v5 - Some references added, minor typos correcte

Role of glycemic control in elective percutaneous coronary interventions in patients with type 2 diabetes

Aim. To assess the association of glycemic control (achievement of an individual target glycated hemoglobin level) with the outcomes of elective percutaneous coronary interventions in patients with type 2 diabetes (T2D).Material and methods. This cohort observational study included 74 patients with a median age of 61 (57; 64) years. There were 49% of men with a previously established T2D, who had indications for elective primary percutaneous coronary intervention (PCI) for stable coronary artery disease. At inclusion in the study and after 1 month, the concentration of fasting blood glucose, glycated hemoglobin (HbA1c), fructosamine, and serum creatinine were determined. Plasma glucose levels were determined using the hexokinase method. HbA1c level was determined by immunoturbidimetry on a Konelab 30i chemistry analyzer. The concentration of fructosamine was determined by the kinetic colorimetric assay on a Konelab 30i chemistry analyzer. Statistical processing was carried out using the Statistica 10.0 program from StatSoft, Inc. (USA).Results. At the time of enrollment, 31% of participants had not achieved the target glycated hemoglobin level against the background of nonoptimal hypoglycemic therapy in most cases. A total of 18 (25%) following adverse cardiovascular events were registered within 12 months after PCI: 11 (15%) patients developed acute coronary syndrome; among them, 6 (8%) patients had stent restenosis according to coronary angiography, 4 (6%) patients — progression of atherosclerosis, which required repeated PCI with stenting of another vessel, 2 (3%) patients — cerebrovascular accident, and 3 (4%) patients were hospitalized due to de compensated heart failure. According to multivariate logistic regression, only the HbA1c level was a predictor of adverse outcomes during the year after PCI — a 1% increase in HbA1c level increased the risk of adverse outcomes by 1,79 times (odds ratio, 1,79, 95% confidence interval, 1,06-3,02, p=0,028). Poor glycemic control 1 month before PCI increased the risk of cardiovascular events by 4,04 times over the next year, while non-target HbA1c level immediately before PCI increased the risk of adverse outcomes by 4,7 times, and 5 months after PCI, by 7,34 times.Conclusion. The significance of non-target glycated hemoglobin level for adverse outcomes during the year after elective PCI against the background of T2D was established with an increase in the negative effect as long-term (after myocardial revascularization) maintenance of poor glycemic control

Asymptotics of Eigenvalues and Eigenfunctions for the Laplace Operator in a Domain with Oscillating Boundary. Multiple Eigenvalue Case

We study the asymptotic behavior of the solutions of a spectral problem for the Laplacian in a domain with rapidly oscillating boundary. We consider the case where the eigenvalue of the limit problem is multiple. We construct the leading terms of the asymptotic expansions for the eigenelements and verify the asymptotics

X-Ray Analysis of Oxygen-induced Perpendicular Magnetic Anisotropy in Pt/Co/AlOx trilayer

X-ray spectroscopy measurements have been performed on a series of Pt/Co/AlOx trilayers to investigate the role of Co oxidation in the perpendicular magnetic anisotropy of the Co/AlOx interface. It is observed that high temperature annealing modifies the magnetic properties of the Co layer, inducing an enhancement of the perpendicular magnetic anisotropy. The microscopic structural properties are analyzed via X-ray Absorption Spectroscopy, X-ray Magnetic Circular Dichroism and X-ray Photoelectron Spectroscopy measurements. It is shown that annealing enhances the amount of interfacial oxide, which may be at the origin of a strong perpendicular magnetic anisotropy

Giant Flare in SGR 1806-20 and Its Compton Reflection from the Moon

We analyze the data obtained when the Konus-Wind gamma-ray spectrometer detected a giant flare in SGR 1806-20 on December 27, 2004. The flare is similar in appearance to the two known flares in SGR 0526-66 and SGR 1900+14 while exceeding them significantly in intensity. The enormous X-ray and gamma-ray flux in the narrow initial pulse of the flare leads to almost instantaneous deep saturation of the gamma-ray detectors, ruling out the possibility of directly measuring the intensity, time profile, and energy spectrum of the initial pulse. In this situation, the detection of an attenuated signal of Compton back-scattering of the initial pulse emission by the Moon with the Helicon gamma-ray spectrometer onboard the Coronas-F satellite was an extremely favorable circumstance. Analysis of this signal has yielded the most reliable temporal, energy, and spectral characteristics of the pulse. The temporal and spectral characteristics of the pulsating flare tail have been determined from Konus-Wind data. Its soft spectra have been found to contain also a hard power-law component extending to 10 MeV. A weak afterglow of SGR 1806-20 decaying over several hours is traceable up to 1 MeV. We also consider the overall picture of activity of SGR 1806-20 in the emission of recurrent bursts before and after the giant flare.Comment: 29 pages including 18 figures; to appear in Astronomy Letters, 2007, 33, p 1-1

Block bond-order potential as a convergent moments-based method

The theory of a novel bond-order potential, which is based on the block Lanczos algorithm, is presented within an orthogonal tight-binding representation. The block scheme handles automatically the very different character of sigma and pi bonds by introducing block elements, which produces rapid convergence of the energies and forces within insulators, semiconductors, metals, and molecules. The method gives the first convergent results for vacancies in semiconductors using a moments-based method with a low number of moments. Our use of the Lanczos basis simplifies the calculations of the band energy and forces, which allows the application of the method to the molecular dynamics simulations of large systems. As an illustration of this convergent O(N) method we apply the block bond-order potential to the large scale simulation of the deformation of a carbon nanotube.Comment: revtex, 43 pages, 11 figures, submitted to Phys. Rev.