Entrainment, stopping, and transmission of microwave solitons of self-induced transparency in counter-propagating magnetized electron beam.

Based on numerical simulations of a boundary problem, we study various scenarios of microwave soliton formation in the process of cyclotron resonance interaction of a short electromagnetic pulse with a counter-propagating initially rectilinear electron beam taking into account the relativistic dependence of the cyclotron frequency on the electrons' energy. When a certain threshold in the pulse energy is exceeded, the incident pulse can propagate without damping in the absorbing beam, similar to the effect of self-induced transparency in optics. However, mutual motion of the wave and electrons can lead to some novel effects. For relatively small energy of the incident pulse, the microwave soliton is entrained by the electron beam opposite to the direction of the wave's group velocity. With an increase in the pulse energy, soliton stopping occurs. This regime is characterized by the close-to-zero pulse velocity and can be interpreted as a variety of the "light stopping." High-energy microwave solitons propagate in the direction of the unperturbed group velocity. Their amplitude may exceed the amplitude of the incident pulse, i.e., nonlinear self-compression takes place. A further increase in the incident energy leads to the formation of additional high-order solitons whose behavior is similar to that of the first-order ones. The characteristics of each soliton (its amplitude and duration) correspond to analytical two-parametric soliton solutions that are to be found from consideration of the unbounded problem.

[Endovascular Treatment of Critical Аоrtic Stenosis: Current State of the Problem and Perspectives].

The article contains the review of current understanding of the etiology and pathogenesis of degenerative aortic stenosis, approaches to surgical treatment depending on various factors, e. g. severity of defect and comorbidity, description of endovascular techniques (balloon valvuloplasty and transcatheter aortic valve implantation), and features of the selection of patients for these procedures. The authors also present assessment of results of operations performed from 2011 to 2016 in the city hospital № 2 in Saint-Petersburg. They analyze data from 72 high-risk aortic stenosis patients aged 81±6 years treated with transcatheter aortic valve implantation. In 68 out of 72 patients (94.4 %) clinical improvement was achieved with reduction of dilation of left ventricular cavity, decrease of functional class of heart failure, and decrease of mean pressure gradient across the aortic valve. A conclusion is made that these results confirm advantages and perspectives of the use of endovascular methods of treatment in this complicated group of patients.

Generation of Rogue Waves in Gyrotrons Operating in the Regime of Developed Turbulence.

Within the framework of the average approach and direct 3D PIC (particle-in-cell) simulations, we demonstrate that the gyrotrons operating in the regime of developed turbulence can sporadically emit "giant" spikes with intensities a factor of 100-150 greater than the average radiation power and a factor of 6-9 exceeding the power of the driving electron beams. Together with the statistical features such as a long-tail probability distribution, this allows the interpretation of generated spikes as microwave rogue waves. The mechanism of spikes formation is related to the simultaneous cyclotron interaction of a gyrating electron beam with forward and backward waves near the waveguide cutoff frequency as well as with the longitudinal deceleration of electrons.

Generation of Subterahertz Superradiance Pulses Based on Excitation of a Surface Wave by Relativistic Electron Bunches Moving in Oversized Corrugated Waveguides.

The first experiments on the observation of short pulsed superradiant (SR) emission with the excitation of a surface wave by a relativistic electron bunch moving in an oversized corrugated waveguide were performed. Subterahertz SR pulses with a central frequency of 0.14 THz, an ultrashort duration of 150 ps, and an extremely high peak power of 50-70 MW were generated. The experiments were based on a theoretical consideration including the quasioptical approach and direct particle-in-cell simulations.

Using Two-Dimensional Distributed Feedback for Synchronization of Radiation from Two Parallel-Sheet Electron Beams in a Free-Electron Maser.

A spatially extended planar 75 GHz free-electron maser with a hybrid two-mirror resonator consisting of two-dimensional upstream and traditional one-dimensional downstream Bragg reflectors and driven by two parallel-sheet electron beams 0.8 MeV/1 kA has been elaborated. For the highly oversized interaction space (cross section 45×2.5 vacuum wavelengths), the two-dimensional distributed feedback allowed realization of stable narrow-band generation that includes synchronization of emission from both electron beams. As a result, spatially coherent radiation with the output power of 30-50 MW and a pulse duration of ∼100 ns was obtained in each channel.

Conversion of an electromagnetic wave into a periodic train of solitons under cyclotron resonance interaction with a backward beam of unexcited electron-oscillators.

The possibility of the conversion of intense continuous microwave radiation into a periodic train of short pulses by means of resonant interaction with a beam of unexcited cyclotron electron oscillators moving backward is shown. In such a system there is a certain range of parameters where the incident stationary signal splits into a train of short pulses and each of them can be interpreted as a soliton. It is proposed to use this effect for amplitude modulation of radiation of short wavelength gyrotrons.

3D quasioptical theory of terahertz superradiance of an extended electron bunch moving over a corrugated surface.

We consider the superradiance of an extended relativistic electron bunch moving over a periodically corrugated surface for the generation of multimegawatt terahertz pulses. To study the above process we have developed a three-dimensional, self-consistent, quasioptical theory of Cherenkov stimulated emission which includes a description of the formation of an evanescent wave over a corrugated surface and its excitation by rf current induced in the electron bunch.

High-power terahertz-range planar gyrotrons with transverse energy extraction.

To increase the output power of terahertz gyrotrons to several hundred kilowatts, we suggest using a planar geometry of interaction space with a sheet electron beam and transverse energy extraction. An advantage of this scheme in comparison with conventional cylindrical geometry is the possibility to ensure effective mode selection over the open transverse coordinate in combination with radiation outcoupling that leads to a substantial reduction of Ohmic losses. Similar to unstable resonators in optics for further growth of the radiation power it is beneficial to introduce waveguide tapering.

Self-induced transparency and electromagnetic pulse compression in a plasma or an electron beam under cyclotron resonance conditions.

Based on analogy to the well-known process of the self-induced transparency of an optical pulse propagating through a passive two-level medium we describe similar effects for a microwave pulse interacting with a cold plasma or rectilinear electron beam under cyclotron resonance condition. It is shown that with increasing amplitude and duration of an incident pulse the linear cyclotron absorption is replaced by the self-induced transparency when the pulse propagates without damping. In fact, the initial pulse decomposes to one or several solitons with amplitude and duration defined by its velocity. In a certain parameter range, the single soliton formation is accompanied by significant compression of the initial electromagnetic pulse. We suggest using the effect of self-compression for producing multigigawatt picosecond microwave pulses.

[Population-based epidemiological study of pulmonary tuberculosis in a number of rural regions of Tatarstan].

The paper presents the results of a population-based, geneticoepidemiological, and immunological study conducted in two regions of Tatarstan. The population-based risks for tuberculosis were established for males and females. Based on the population and family data, the authors calculated the genetic liability to tuberculosis, namely hereditability that is in the range of 0.8 to 1.0 and includes the contribution of nongenetic and environmental factors. Analysis of the results of immunogenetic studies of the northwestern region of Tatarstan has ascertained that patients have an association with the HLA antigen B22, in the Kama Region there is an association with other HLA antigens: B12 and B16. The higher frequency of the HLA antigens B28 and CW1 in healthy individuals as compared with that in patients with pulmonary tuberculosis (PT) suggests the resistance of PT carriers of these antigens for the disease. A study of the distribution of HLA genes by polymerase chain reaction has established the association of the disease with the DR-B1-15 genes in the Kama Region.

Experimental and theoretical studies of a coaxial free-electron maser based on two-dimensional distributed feedback.

The first operation of a coaxial free-electron maser (FEM) based on two-dimensional (2D) distributed feedback has been recently observed. Analytical and numerical modeling, as well as measurements, of microwave radiation generated by a FEM with a cavity defined by coaxial structures with a 2D periodic perturbation on the inner surfaces of the outer conductor were carried out. The two-mirror cavity was formed with two 2D periodic structures separated by a central smooth section of coaxial waveguide. The FEM was driven by a large diameter (7 cm), high-current (500 A), annular electron beam with electron energy of 475 keV. Studies of the FEM operation have been conducted. It has been demonstrated that by tuning the amplitude of the undulator or guide magnetic field, modes associated with the different band gaps of the 2D structures were excited. The Ka-band FEM generated 15 MW of radiation with a 6% conversion efficiency, in good agreement with theory.

Generation of Cherenkov superradiance pulses with a peak power exceeding the power of the driving short electron beam.

Theoretical investigation of a short electron beam (extended bunch) interaction with a backward wave propagating in a slow wave structure demonstrates the possibility of producing ultrashort superradiance pulses with a peak power which exceeds the power of the driving beam (conversion factor K>1). It is shown that a nonuniform slow wave structure with optimized profile is beneficial in order to increase the conversion factor. The results of theoretical analysis are confirmed by the experiments. At X band using the SINUS-150 accelerator (4 ns, 330 kV, 2.6 kA) 0.6-0.8 ns superradiance pulses with a peak power of 1.2 GW and a conversion factor of 1.5 were obtained. Similar experiments at Ka-band based on the RADAN-303 accelerator (1 ns, 290 kV, 2.5 kA) demonstrated production of the superradiance (SR) pulse with duration 200 ps and peak power about 1 GW (conversion factor of 1.4).

[The use of discrete characters in discriminant analysis for diagnosis of pulmonary tuberculosis and for classification of patients differing in treatment efficiency based on polymorphisms at nine codominant loci-HP, GC, TF, PI, PGM1, GLO1, C3, ACP1 and ESD]. / Ispol'zovanie diskretnykh priznakov v diskriminantnom analize pri diagnostike tuberkuleza legkikh i pri klassifikatsii bol'nykh s razlichnoi éffektivnost'iu lecheniia po raspredeleniiu polimorfizmov v deviati kodominantnykh lokusakh-HP, GC, TF, PI, PGM1, GLO1, C3, ACP1 i ESD.

Discriminant analysis was used to differentiate patients with pulmonary tuberculosis (N = 106) from healthy individuals (N = 328) and patients whose treatment was efficient (N = 71) from those whose treatment was inefficient (N = 35). The analysis involved the data on nine polymorphic codominant loci: HP, GC, TF, PI, PGM1, GLO1, C3, ACP1, and ESD. The loci were selected by significance of differences in genotype frequencies between tuberculosis patients and healthy controls (GC, TF, PI, C3, ACP1) or between the two groups of patients differing in treatment efficiency (HP, GC, PI, PGM1, C3, ESD). Discrimination was based on a graphic method of Bayes classification procedure with a single-variate nomograph allowing easy estimation of the a posteriori probabilities for an individual to be classified. The two groups of patients proved to be discriminated sufficiently well (probability of misclassification Perr = 0.24), whereas discrimination between tuberculosis patients and healthy individuals was less efficient (Perr = 0.33). The method was proposed as a means of predicting the efficiency of treatment in pulmonary tuberculosis. Along with clinical, roentgenological, and laboratory examination, discriminant analysis may be employed as an accessory test in diagnostics of pulmonary tuberculosis, especially when the diagnosis is questionable.

Observation of chaotic dynamics in a powerful backward-wave oscillator.

Self-modulation regimes of generation in a powerful 10-micros X-band backward-wave oscillator were studied theoretically and experimentally. The sequence of the self-modulation patterns and corresponding bifurcation values observed as the current was increased were in good agreement with the results of simulations. It was found that at a current of 120 A chaotic self-modulation set in at a power of 2 MW and a relative spectral width of 4%.

[The use of the expectation-maximization (EM) algorithm for maximum likelihood estimation of gametic frequencies of multilocus polymorphic codominant systems based on sampled population data]. / Otsenka maksimal'nogo pravdopodobiia chastot gamet polilokusnykh polimorfnykh kodominantnykh sistem po vyborochnym populiatsionnym dannym s ispol'zovaniem algoritma "ozhidanie-maksimizatsiia" (OM-algoritm).

Estimation of gametic frequencies in multilocus polymorphic systems based on the numerical distribution of multilocus genotypes in a population sample ("analysis without pedigrees") is difficult because some gametes are not recognized in the data obtained. Even in the case of codominant systems, where all alleles can be recognized by genotypes, so that direct estimation of the frequencies of genes (alleles) is possible ("complete data"), estimation of the frequencies of multilocus gametes based on the data on multilocus genotypes is sometimes impossible, whether population data or even family data are used for studying genotypic segregation or analysis of linkage ("incomplete data"). Such "incomplete data" are analyzed based on the corresponding genetic models using the expectation-maximization (EM) algorithm. In this study, the EM algorithm based on the random-marriage model for a nonsubdivided population was used to estimate gametic frequencies. The EM algorithm used in the study does not set any limitations on the number of loci and the number of alleles of each locus. Locus and alleles are identified by numeration making possible to arrange loops. In each combination of alleles for a given combination of m out of L loci (L is the total number of loci studied), all alleles are assigned value 1, and the remaining alleles are assigned value 0. The sum of zeros and unities for each gamete is its gametic value (h), and the sum of the gametic values of the gametes that form a given genotype is the genotypic value (g) of this genotype. Then, gametes with the same h are united into a single class, which reduces the number of the estimated parameters. In a general case of m loci, this procedure yields m + 1 classes of gametes and 2m + 1 classes of genotypes with genotypic values g = 0, 1, 2, ..., 2m. The unknown frequencies of the m + 1 classes of gametes can be represented as functions of the gametic frequencies whose maximum likelihood estimations (MLEs) have been obtained in all previous EM procedures and the only unknown frequency (Pm(m)) that is to be estimated in the given EM procedure. At the expectation step, the expected frequencies (Fm(g) of the genotypes with genotypic values g are expressed in terms of the products of the frequencies of m + 1 classes of gametes. The data on genotypes are the numbers (ng) of individuals with genotypic values g = 0, 1, 2, 3, ..., 2m. The maximization step is the maximization of the logarithm of the likelihood function (LLF) for ng values. Thus, the EM algorithm is reduced, in each case, to solution of only one equation with one unknown parameter with the use of the ng values, i.e., the numbers of individuals after the corresponding regrouping of the data on the individuals' genotypes. Treatment of the data obtained by Kurbatova on the MNSs and Rhesus systems with alleles C, Cw, c, D, d, E, e with the use of Weir's EM algorithm and the EM algorithm suggested in this study yielded similar results. However, the MLEs of the parameters obtained with the use of either algorithm often converged to a wrong solution: the sum of the frequencies of all gametes (4 and 12 gametes for MNSs and Rhesus, respectively) was not equal to 1.0 even if the global maximum of LLF was reached for each of them (as it was for MNSs with the use of Weir's EM algorithm), with each parameter falling within admissible limits (e.g., [0, min(PN,Ps)] for PNs). The chi 2 function is suggested to be used as a goodness-of-fit function for the distribution of genotypes in a sample in order to select acceptable solutions. However, the minimum of this function only guarantee the acceptability of solutions if all limitations on the parameters are met: the sum of estimations of gametic frequencies is 1.0, each frequency falls within the admissible limits, and the "gametic algebra" is complied with (none of the frequencies is negative).

[Heterozygosity in patients with pulmonary tuberculosis showing varying responses to therapy]. / Issledovanie urovnei geterozigotnosti u bol'nykh tuberkulezom legkikh s razlichnoi éffektivnost'iu lecheniia.

The distribution of the levels of heterozygosity was analyzed by 9 loci of genetic markers: PI, TF, PGM1, ACPI, HP, GC, GLO1 C3, and ESD in two groups of patients with pulmonary tuberculosis who had improvements (Group 1, n = 71) and failures (Group 2, n = 35). The heterozygosity observed in the groups was compared with that calculated by the Hardy-Weinberg law by using data on healthy controls (n = 328; the locus ESD was investigated in 78 healthy individuals). The analysis indicated that there were statistically significant deviations of the observed heterozygosities, g1, at 4 loci (GC, PI, C3, and ACPI) from the expected ones; h1 calculated from the data in the control group. The observed heterozygisities were higher than the expected ones at 3 loci (PI, C3, and ACPI), and at the GC locus. the observed heterozygosity being lower than the expected one. Comparing the observed heterozygosities. g1, within the loci, by using Fisher's exact test revealed significant differences between the groups of patients and healthy controls at the same loci, which showed significant differences between the observed and expected heterozygosities. There were no differences between the groups of patients by the observed heterozygosities. The mean expected heterozygosity were h = 0.386 +/- 0.056. The mean observed heterozygosity, were g = 0.415 +/- 0.037, 0.402 +/- 0.061, 0.371 +/- 0.055 in Groups 1 and 2 and in the controls, respectively. There were no differences between the mean expected and obsorved heterozygosities or between the mean observed heterozygosities in the three groups under study. It is proposed that a single locus rather than the mean heterozygosities should be used as a generalized nonspecific measure of genetic control over diseases while the former can show the involvement of a specific marker locus to develop a disease, the latter can simply veil the effects of each of the loci alone. Thus, the findings produce strong evidence for that there is a genetic control in the development of pulmonary tuberculosis.

[Analysis of heterozygosity levels at P1,TF, PGM1, ACP1, HP, GC, GLO, C3, and ESD loci in pulmonary tuberculosis patients with different treatment outcomes]. / Analiz urovnei geterozigotnosti po lokusam PI, TF, PGM1, ACP1, HP, GC, GLO1, C3 i ESD u bol'nykh tuberkulezom legkikh s razlichnoi éffektivnost'iu lecheniia.

Heterozygosity at nine genetic loci (PI, TF, PGM1, ACP1, HP, GC, GLO1, C3, and ESD) was analyzed in pulmonary tuberculosis patients with good (group 1, N = 71) and poor (group 2, N = 35) response to treatment. The observed heterozygosities were compared with the expected values, which were calculated from allele frequencies in a control sample of healthy individuals (N = 328 with all but one locus and 78 with ESD) according to Hardy-Weinberg expectations. The analysis showed that the observed heterozygosities gl of patients significantly differed from the expected values hl in the case of four loci (GC, PI, C3, and ACP1). The observed heterozygosity was higher than expected in three cases (PI, C3, and ACP1) and lower then expected (GC) in one case. When data on each individual locus were compared using Fisher's exact test, both groups of patients proved to significantly differ (PF < 0.05) from the control group in the same four loci. No difference in observed heterozygosity was detected between the two groups of patients. The mean expected heterozygosity was h = 0.386 +/- 0.00674; the mean observed heterozygosity was g = 0.415 +/- 0.02 in group 1, g = 0.402 +/- 0.026 in group 2, and g = 0.371 +/- 0.00955 in the control group. The t test did not reveal a significant difference between the mean values of expected observed heterozygosities. Heterozygosity at individual loci, rather than mean heterozygosity, was proposed as an integral nonspecific indicator of the genetic control of a disease, because the former directly implicates individual marker loci in the development of a disorder, whereas effects of individual loci may eliminate each other when mean heterozygosity is computed. Based on the results obtained, a genetic control was assumed for the development of the tuberculosis process in the lungs.

[Calculation of the morbid risk in genetic-epidemiologic studies of age-dependent diseases]. / Raschet morbidnogo riska v genetiko-épidemiologicheskikh issledovaniiakh vzrast-zavisimykh zabolevanii.

Distributions of age at onset are widely used in the genetic epidemiology of age-dependent diseases. Examples are estimation of recurrent risks in genetic counselling and testing genetic hypotheses in segregation and linkage analyses. In this study, morbidity parameters are defined, including age-specific morbidity rates, morbidity net risk (incidence), and cumulative incidence (population risk, an integrated measure of population susceptibility to the disease at the moment of the study). Age-specific morbidity risks are calculated from the respective morbidity rates, which are analogous to mortality rates used in demography. Population data typically used for calculation of morbidity rates are discussed. Methods of calculation of morbidity rates based on the data of single and interval epidemiological studies are described. Methods for calculating standard errors of these parameters, estimating their statistical reliability, and testing statistical hypotheses are discussed.

[Epidemiological and immunogenetic analysis of tuberculosis and diabetes mellitus association]. / Epidemiologicheskii i immunogeneticheskii analiz vzaimosviazi tuberkuleza i sakharnogo diabeta.

The prevalence of insulin-dependent diabetes mellitus (IDDM) and noninsulin-dependent diabetes mellitus (NIDDM) among adults in two Moscow okrugs was studied. It was 0.218 and 1.678%, respectively, the latter form being encountered 7.7 times more frequently. Patients with pulmonary tuberculosis followed at tuberculosis control dispensaries (n = 69,012) were found to have diabetes mellitus in 236 cases (120 with IDDM and 116 with NIDDM). The prevalence of IDDM among the tuberculosis control dispensary patients was 1.7%, which was 8 times greater than that in the general population. That of NIDDM was 1.68%, which did not significantly differ from that in the population. Epidemiological analysis showed that there was a highly significant association of tuberculosis with diabetes mellitus in the population. The risk for IDDM was 3.6% in patients and exceeded that in the population while the risk for NIDDM in the population was the same as that in the population. Analyzing the distribution of immunogenetic HLA-1 and HLA-2 markers showed that patients with tuberculosis concurrent with IDDM were intermediate between a group of patients with isolated tuberculosis and isolated IDDM.