Integrative Modeling of Electrical Properties of Pacemaker Cardiac Cells

This work represents modeling of electrical properties of pacemaker (sinus) cardiac cells. Special attention is paid to electrical potential arising from transmembrane current of Na{+}, K{+} and Ca{2+} ions. This potential is calculated using the NaCaX model. In this respect, molar concentration of ions in the intercellular space which is calculated on the basis of the GENTEX model is essential. Combined use of two different models allows referring this approach to integrative modeling

Markers of endothelial dysfunction in adolescent and young patients with hypothalamic syndrome

Background: Endothelial dysfunction is the first but reversible stage of atherosclerosis. A change in the functional state of the vascular endothelium, especially of a growing organism, can be the basis for the development of many diseases in adulthood. The study of the structural and functional state of peripheral vessels of adolescents with hypothalamic syndrome is extremely important for understanding of the mechanisms of formation of cardiometabolic risks.Aims: to compare the structural and functional state of the vascular wall of young men with hypothalamic syndrome and constitutionally exogenous obesity.Methods: During the study 360 males were examined (average age 21.27±2.44 years) and divided into 3 groups: group 1 -with hypothalamic syndrome (n=242); group 2 - with constitutionally exogenous obesity (n=98); control group - practically healthy individuals (n=20). Hypothalamic syndrome was verified in the presence of a symptom complex, including obesity and pink striae. Cross-group comparative analysis of results of clinical, laboratory and instrumental examination was carried out.Results: In the group of patients with hypothalamic syndrome, endothelium-dependent vasodilatation (9.44±1.26 versus 10.37±1.21%; p=0.001) and endothelium-independent vasodilatation (10.29±1.28 versus 11.29±1.14%; p=0.001) is worse than in the group of patients with constitutionally exogenous obesity, and the rate of endothelium-dependent vasodilatation is lower than the generally accepted norm. In addition, among patients with hypothalamic syndrome, the stiffness of the vascular wall is higher than among patients with constitutionally exogenous obesity (15.47±2.58 versus 13.24±3.84%; p=0.001). Statistically significant correlations were revealed between the structural and functional state of peripheral arteries and hemodynamic, hormonal, metabolic changes, and the level of C-reactive protein (p<0.05).Conclusions: The obtained data indicate a deterioration of endothelial function and an increase in vascular wall stiffness in obese patients, regardless of its etiology. The patients with hypothalamic syndrome have more pronounced structural and functional changes in the vascular wall are observed than patients with constitutionally exogenous obesity

Rhinocerebral Form of Invasive Mycosis in COVID-19 Patients: Clinical Course, Diagnosis, Treatment Experience

Background. The incidence of invasive mycoses is reported to increase among patients with a history of new coronavirus infection COVID-19. Adhesion and damage of endothelial cells by zygomycetes lead to fungus angioinvasion, release of a large number of fungal proteases, lipases and mycotoxins, as well as vascular thrombosis, subsequent necrosis of tissues.Objectives. Improvement of the diagnosis and treatment for COVID-19 associated invasive mycosis.Methods. Examination and treatment of 143 patients with invasive mycosis of the maxillofacial area in the period from August 2021 to May 2022 at the Maxillofacial Unit of Regional Clinical Hospital of Emergency Medical Care, Krasnodar Krai, Russia. The diagnosis was confi rmed by cytological, culture-based methods, as well as pathomorphological study of surgical specimen. Follow-up monitoring was carried out in 1, 3, 6 months, with repeated CT and MRI investigations. The group under follow-up monitoring included 91 patients. The incidence of signs was determined via descriptive statistics methods in proportion of the total number of observations and expressed as a percentage. Statistika 12.5 and Excel 2010 (Windows 10) were used in the study, the graphical representation of the material was made in the same programs.Results. Manifestation of invasive mycoses of the maxillofacial area occurred during the early convalescent period of coronavirus infection in specialized infectious hospitals or within two weeks after discharge from the hospital. A typical clinical picture includes rhinocerebral zygomycosis with the development of fungal osteomyelitis of the upper jaw, nasal bones, zygomatic bone, ethmoidal labyrinth bones, sphenoid bone, frontal bone. 17 cases (11.9%) had a lethal outcome as a result of disseminated form of fungal infection caused by Mucorales (14 patients), Aspergillus (3 patients) with damage to the brain, lungs, kidneys and fatal massive necrotic lesions of the craniofacial area. An integrated approach embraced early antifungal therapy (Amphotericin B) as well as surgical debridement of the lesions and provided a positive effect in treatment.Conclusion. Invasive fungal infections require prompt diagnosis and early prescription of antifungal therapy (prior to histological confi rmation of diagnosis) to minimize consequences and prevent fatal outcome. Due to the nonspecifi c nature of clinical symptoms and diffi culties of early diagnosis of invasive zygomycosis and aspergillosis, it is necessary to be alert to potential invasive aggressive mycoses in immunocompromised patients who have a history of a new coronavirus infection COVID-19

Disorder-Induced Critical Phenomena in Hysteresis: Numerical Scaling in Three and Higher Dimensions

We present numerical simulations of avalanches and critical phenomena associated with hysteresis loops, modeled using the zero-temperature random-field Ising model. We study the transition between smooth hysteresis loops and loops with a sharp jump in the magnetization, as the disorder in our model is decreased. In a large region near the critical point, we find scaling and critical phenomena, which are well described by the results of an epsilon expansion about six dimensions. We present the results of simulations in 3, 4, and 5 dimensions, with systems with up to a billion spins (1000^3).Comment: Condensed and updated version of cond-mat/9609072,``Disorder-Induced Critical Phenomena in Hysteresis: A Numerical Scaling Analysis'

Behavioral and social risk factors for metabolically unhealthy obesity: data form a 12-year prospective study in the Russian population

Aim. To study the contribution of behavioral and social risk factors to the development of metabolically unhealthy obesity (MUO) according to a prospective study in the Russian population.Material and methods. From the HAPPIE project, 3197 people aged 45-69 years with a body mass index ≥30 kg/m2 were selected, who had all the necessary parameters for obesity phenotype determination. The prospective analysis included the first (2003-2005) and third screenings (2015-2017). A subsample was formed (n=1275; 276 men — 22%, 999 women — 78%). The mean follow-up period was 12,4 years. IDF criteria (2005) were taken for analysis.Results. Men with a metabolically healthy obesity (MHO) phenotype most often have a secondary and higher education, while women with MHO — vocational and secondary education. In women, secondary education was most often noted. Among persons with obesity, both men and women are more often not single, while having MUO as follows: 56,8% and 34,2%, respectively. Men and women have a low-intensity activity, regardless of the obesity phenotype. The prevalence of smoking in the present time does not differ in the MHO and MUO groups. Metabolically healthy women consume more alcohol than those with MUO. In men with sedentary lifestyle and fasting hyperglycemia, the risk of MUO over a 12-year follow-up period was significantly higher. In women, the risk of conversion from MHO to MUO is increased when blood pressure (BP) is ≥130/85 mmHg.Conclusion. In the Russian population, the risk of MUO in men increases with a level of physical activity <3 h/week and a blood glucose level ≥6,1 mmol/l; in women, only BP ≥130/85 mm Hg contributes to the development of MUO

Three-loop critical exponents, amplitude functions, and amplitude ratios from variational perturbation theory

We use variational perturbation theory to calculate various universal amplitude ratios above and below T_c in minimally subtracted phi^4-theory with N components in three dimensions. In order to best exhibit the method as a powerful alternative to Borel resummation techniques, we consider only to two- and three-loops expressions where our results are analytic expressions. For the critical exponents, we also extend existing analytic expressions for two loops to three loops.Comment: Author Information under http://www.physik.fu-berlin.de/~kleinert/institution.html . Latest update of paper (including all PS fonts) at http://www.physik.fu-berlin.de/~kleinert/kleiner_re318/preprint.htm

Critical Exponents of the N-vector model

Recently the series for two RG functions (corresponding to the anomalous dimensions of the fields phi and phi^2) of the 3D phi^4 field theory have been extended to next order (seven loops) by Murray and Nickel. We examine here the influence of these additional terms on the estimates of critical exponents of the N-vector model, using some new ideas in the context of the Borel summation techniques. The estimates have slightly changed, but remain within errors of the previous evaluation. Exponents like eta (related to the field anomalous dimension), which were poorly determined in the previous evaluation of Le Guillou--Zinn-Justin, have seen their apparent errors significantly decrease. More importantly, perhaps, summation errors are better determined. The change in exponents affects the recently determined ratios of amplitudes and we report the corresponding new values. Finally, because an error has been discovered in the last order of the published epsilon=4-d expansions (order epsilon^5), we have also reanalyzed the determination of exponents from the epsilon-expansion. The conclusion is that the general agreement between epsilon-expansion and 3D series has improved with respect to Le Guillou--Zinn-Justin.Comment: TeX Files, 27 pages +2 figures; Some values are changed; references update

Thermodynamic characteristics of the classical n-vector magnetic model in three dimensions

The method of calculating the free energy and thermodynamic characteristics of the classical n-vector three-dimensional (3D) magnetic model at the microscopic level without any adjustable parameters is proposed. Mathematical description is perfomed using the collective variables (CV) method in the framework of the $\rho^4$ model approximation. The exponentially decreasing function of the distance between the particles situated at the N sites of a simple cubic lattice is used as the interaction potential. Explicit and rigorous analytical expressions for entropy,internal energy, specific heat near the phase transition point as functions of the temperature are obtained. The dependence of the amplitudes of the thermodynamic characteristics of the system for $T>T_c$ and $T<T_c$ on the microscopic parameters of the interaction potential are studied for the cases $n=1,2,3$ and $n\to\infty$. The obtained results provide the basis for accurate analysis of the critical behaviour in three dimensions including the nonuniversal characteristics of the system.Comment: 25 pages, 5 figure

Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

Search for anomalous t t-bar production in the highly-boosted all-hadronic final state

A search is presented for a massive particle, generically referred to as a Z', decaying into a t t-bar pair. The search focuses on Z' resonances that are sufficiently massive to produce highly Lorentz-boosted top quarks, which yield collimated decay products that are partially or fully merged into single jets. The analysis uses new methods to analyze jet substructure, providing suppression of the non-top multijet backgrounds. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 5 inverse femtobarns. Upper limits in the range of 1 pb are set on the product of the production cross section and branching fraction for a topcolor Z' modeled for several widths, as well as for a Randall--Sundrum Kaluza--Klein gluon. In addition, the results constrain any enhancement in t t-bar production beyond expectations of the standard model for t t-bar invariant masses larger than 1 TeV.Comment: Submitted to the Journal of High Energy Physics; this version includes a minor typo correction that will be submitted as an erratu