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Magnetic impurities deposited on the surface of a thin film experience oscillating-in-space indirect exchange interaction even if the chemical potential is pinned to a middle gap position in the surface electron spectrum, preventing free electrons and holes to exist in the ground state. Oscillating interaction mediated by massive Dirac fermions is a signature of the topologically nontrivial state.

Tuberculosis (TB) is one of the most important concerns of public health. There is evidence suggesting that genetic status is responsible for predisposition to infectious diseases including TB. To determine genetic risk factors of TB development, the frequencies of polymorphisms of genes CYP1A1, CYP2D6, CYP2C9, CYP2C19, GSTT1, GSTM1, NAT2, MDR1, and NRAMP1 in 73 TB patients and 352 healthy individuals were determined by allele-specific hybridizatio n using microarray technology. The TB patients have shown a significant increase in the frequency of the null GSTT1 genotype (OR = 3.26, 95% CI = 1.91–5.55, p = 0.000028) as well as the double null GSTT1/GSTM1 genotype (OR = 4.05, 95% CI = 2.14-7.65,p = 0.000034) compared to the group of healthy donors. It was shown that the NAT2* 5/* 5 genotype in combination with the “null” GSTT1 and the double “null” GSTT1/GSTM1 genotypes was observed significantly more often in the TB patients than in the control sample. Thus the examined GSTT1, GSTM1 and NAT2 gene polymorphisms may potentially alter the risk of TB development in ethnic Russians and are of interest for further research using larger cohorts of patients.

The test-system "Sensititre MycoTB" was applied to analyze 159 cultures of M.tuberculosis isolated from patients with tuberculosis. According data of investigation in "Bactec 960" they are identified as cultures with multiple medicinal sensitivity. The detailed analysis of results of application of mentioned test-system (mycoTB) demonstrated that significant part of cultures with multiple medicinal sensitivity is sensitive to anti-tuberculosis pharmaceuticals. The significant part of cultures is characterized by "intermediate" sensitivity/resistance than can be established by mentioned test-system. This data permits enlarging possibilities of chemotherapy of tuberculosis.

We present a theoretical analysis and results of modeling of a new integrated device for spintronics application, which is based on a hybrid metal–semiconductor structure. The proposed device consists of a Si-based p–i–n photodetector sandwiched between two layers of a ferromagnetic metal (3d ferromagnet or half-metallic compound). Electron–hole pairs are created in the semiconductor part of the structure by light illumination. The photocurrent flowing in such a system is shown to depend on its magnetic configuration. This is due to a difference in the specular reflection (as well as in the diffuse scattering) of spin-up and spin-down electrons and holes from magnetically polarized layers—similar to giant magnetoresistance effect in magnetic multilayers. This, in turn, allows controlling the device performance by an externally applied magnetic field. We have estimated magnitude of the effect and also determined the role of relevant material parameters.

We present a general approach to the problem of a ferromagnetic phase transition in diluted magnetic semiconductors with free carriers. The Curie temperature of ferromagnetic transition is calculated in the mean field approximation. The approach allows to analyze the effects of magnetic fluctuations and disorder on the Curie temperature. We also propose a new mechanism of exchange interaction between magnetic impurities at vanishing concentration of free carriers.

We analyze critical temperature of ferromagnetic ordering in diluted magnetic semiconductors in the mean-field approximation. Using a general field-theoretical approach we formulate a description of magnetic phase transition, which takes into account the interaction of magnetic fluctuations. We also propose a mechanism of exchange interaction between Mn impurity moments in GaMnAs alloys via the Mn-induced acceptor levels. This mechanism may lead to low temperature ferromagnetism at vanishing concentration of free carriers.

The effective Hamiltonian that describes magnetic exchange interaction in a topological insulator is calculated, projecting bulk contact $s$-$d$ interaction onto surface electron states. This model consistently describes the indirect exchange between magnetic atoms mediated either by massless Dirac fermions in thick films or by massive excitations in a thin slab with tunneling between opposite surfaces. It is shown that an effective $s$-$d$ exchange is sensitive to the symmetry of surface wave functions and depends on the position of an impurity spin relative to slab surfaces. Under a vertical bias the indirect exchange between localized spins is switchable between opposite surfaces, and the oscillating range function reveals zero magnetic field beating as a signature of Rashba spin splitting.

The convenient basis representation for the valence band Hamiltonian in wurtzite semiconductors is proposed and the polarization selection rules in GaN-based quantum wells are found. The polarization dependent optical matrix elements in quantum wells are calculated for a finite in-plane electron momentum, that allows to calculate peak optical gain and laser threshold in the GaN-based quantum well structures. This article also addresses the role of alloy inhomogeneities in the optical gain in quantum well lasers. The peak gain is found as a function of statistical broadening caused by the In-content fluctuations. It is shown that the composition fluctuations in the active region influence the gain differently depending on a light polarization. The absolute value of the calculated gain is found to be in agreement with the experiment.

The mechanism of valence-state formation in the IV-VI alloys doped with rare-earth impurities is analyzed with respect to certain properties of narrow-gap semiconductors. The mean-field approximation in the slaveboson representation is used to account for the strong electron correlation at the impurity. The energy, width, and filling factor of the impurity level are calculated as a function of both the band gap and position of the chemical potential. We also calculate the temperature dependence of the magnetic susceptibility of an impurity. It is shown that mixing to coupled conduction- and valence-band states makes the properties of rare-earth dopants sensitive to the band gap and Fermi level in the narrow-gap semiconductor host. @S0163-1829~99!08723-8#

The results of calculation of the indirect exchange interaction between magnetic layers are presented for the case of a structure with narrow-gap semiconducting IV–VI quantum well. The main mechanism is a magnetic polarization of the size-quantized electrons and holes inside the well. This type of interaction is suggested for the explanation of recent experiments on EuS/PbS structures.

Relaxation kinetics in a quantum cascade intersubband laser are investigated. Distribution functions and gain spectra of a three-subband double-quantum-well active region are obtained as a function of temperature and injection current. The potentially important role of the nonequilibrium phonons at lasing threshold is shown and discussed in details. It is shown that the threshold current is strongly dependent of the power dissipated in the active region in steady state. The numerical calculations for an 8.5 μm laser illustrate the general issues of relaxation kinetics in quantum cascade lasers. Temperature dependence of the threshold current is obtained in a good agreement with the experiments.

The frequency of mutations causing drug resistance in MTB isolates were studied in the respiratory material obtained from TB-patients in the Moscow Region. In izoniazid-resistant isolates, the most prevalent mutation was found to be the Ser315Thr substitution in the katG gene (15.8%) whereas the most frequent mutations in multidrug-resistant isolates were Ser531Leu and Ser315Thr in the rpoB and katG genes (26.3%), or a combination of these two substitutions with a T15 mutation in the inhA gene (5.3%). We compared performance of three molecular assays--"TB-BIOCHIP" ("BIOCHIP-IMB", Ltd, Russia), Xpert MTB/RIF ("Cepheid", USA) and GenoType MTBDRplus ("Hain Life-science", Germany), with the efficiency of luminescent microscopy, and phenotypic drug-suscepibility testing in an automated system BACTEC MGIT 960 (Becton, Disckinson and Company, USA). Xpert MTB/RIF, TB-BIOCHIP and GenoType MTBDRplus detected MTB in sputum in 92, 78 and 49% of all culture-positive cases, respectively. The agreement between standard cultural data and molecular DST results for Xpert MTB/RIF (resistance towards rifampicin), for TB-BIOCHIP and GenoType MTBDRplus (resistance towards rifampicin and izoniazid) amounted to 100, 97 and 100% respectively. Summing up, Xpert MTB/RIF was concluded to be the most efficient assay for primary detection of MTB, whereas the TB-BIOCHIP was shown to be the only molecular assay sensitive enough for simultaneous detection of MTB DNA and for revealing multidrug resistance in sputum (i.e. resistance to both first-line anti-TB drugs, rifampicin and izoniazid).

We study the magnetic density distribution created by a separate magnetic impurity placed inside a IV-VI semiconductor quantum well. The absence of carriers is assumed, so that the induced magnetic density is due to virtual electron-hole excitations. The origin of this effect is analogous to the vacuum screening of charge in quantum electrodynamics. We calculate the magnetic density for different positions of the impurity within the well. The interaction between magnetic impurities in the quantum well is also calculated.

We discuss the properties of AlGaN∕GaN superlattice (SL) related to the feasibility of a terahertz-range oscillator. The distortion of the conduction-band profile by the polarization fields has been taken into account. We have calculated the conduction-band offset between the pseudomorphic AlGaN barrier and the GaN quantum well, the first miniband width and energy dispersion, as functions of Al content in the barrier. As the short-period SL miniband energy dispersion contains contributions from next to nearest neighbors, it causes anharmonic electron oscillations at the multiples of the fundamental Bloch frequency. The Al content and SL period that favor high-frequency oscillations have been determined.

To analyse the electronic properties of semiconductor superlattices (SLs) or quantum wells (QWs) it is necessary to know the basic parameters of the layers of which the structures are composed: the band gaps, effective masses parallel to the interfaces, etc. In turn, to determine those parameters properly, it is necessary to take into account the strains in the interfaces as well as in the bulk of the layers. The strain induced energy shifts are usually calculated from the corresponding deformation potentials (DPs). For SLs and QWs made of the IV—VI semiconducting materials, the strain induced shifts of energy levels are considered in Refs. [1-4]. It is commonly assumed that the DPs in QWs and SLs are the same as those in bulk crystals. For example, for the DPs of PbTe and SnTe SLs theoretical results of Refs. [5] and [6] are taken as a rule. The purpose of the present contribution is to consider the difference between DPs in QWs and bulk material. We show that such difference does exist for the case of narrow-gap materials with the interband k—p interaction. This is because of pronounced effect of the size quantization on energy levels in QWs made of the narrow-gap materials.

The dependence of the Hall coefficient on magnetic field (B < 1.5 T), measured at 77 K, in short-period (D < 40 nm), strained PbTe superlattices is analysed and interpreted. It is concluded that the superlattice is of type II. In addition to the electrons in PbTe and holes in SnTe, a third kind of charge carriers, having a high mobility, appears to take part in the conduction process. The third carriers can be both electron and hole-like particles. Those carriers are connected with interface states which are expected to exist at the PbTe/SnTe interface. The carrier concentrations and mobilities in the bulk of the layers and at the interface are determined. [Russian Text Ignored].

The interaction of spins localized within the band-inverted heterojunction with the Weyl excitations is shown to differ significantly from the usual s—d interaction. The indirect exchange interaction is long-range and antiferromagnetic. The magnitude of interaction decreases with the distance as R-3 . The effective interaction depends on the parameters of electron energy spectrum and parameters of the heterojunction as well. It consists of anisotropic Heisenberg term and of pseudodipole terms.

Seeding of 117,579 samples of clinical materials at the Central Microbiological Laboratory, Moscow Research and Practical Centre of Tuberculosis, resulted in isolation of 15,786 (13,4%) mycobacterial cultures, with 15,333 (97.1%) ones being identified as M. tuberculosis complex and 490 (3.1%) as non-tuberculosis mycobacteria (NTM). Samples collected in the Moscow region were dominated by MAC, M. kansasii, M. xenopi, and M. fotuitum. Cultivation on solid and liquid media in an automated regime was shown to be optimal for isolation of NTM. Comparison of mycobacteria identification by microbiological methods and by high performance liquid chromatography revealed excellent agreement between the results (96.1%), with the latter technique taking less time to obtain them. Agreement between identification of acid-resistant mycobacterial cultures using the MAIS-dif test system and microbiological methods was estimated at 93.5%. IMS biochips may also be used to detect species composition of myobacteria because only one case of disagreement with the results of microbiological methods was documented in the study of 108 cultures by the two techniques.

Tuberculosis (TB) is one of the most important concerns of public health. There is evidence suggesting that genetic status is responsible for predisposition to infectious diseases including TB. To determine genetic risk factors of TB development, the frequencies of polymorphisms of genes CYP1A1, CYP2D6, CYP2C9, CYP2C 19, GSTT1, GSTM1, NAT2, MDR1, and NRAMP1 in 73 TB patients and 352 healthy individuals were determined by allele-specific hybridization using microarray technology. The TB patients have shown a significant increase in the frequency of the null GSTT1 genotype (OR = 3.26, 95% CI = 1.91 - 5.55, p = = 0.000028) as well as the double null GSTT1/GSTM1 genotype (OR = 4.05, 95% CI = 2.14 -7.65, p = = 0.000034) compared to the group of healthy donors. It was shown that the NAT2*5/*5 genotype in combination with the "null" GSTT1 and the double "null" GSTT1/GSTM1 genotypes was observed significantly more often in the TB patients than in the control sample. Thus the examined GSTT1, GSTM1 and NAT2 gene polymorphisms may potentially alter the risk of TB development in ethnic Russians and are of interest for further research using larger cohorts of patients.

The energy spectrum of a quantum dot made from IV—VI narrow gap semiconductors is studled. The calculations of the energy levels as functions of the dot radius are performed. When the anisotropy of the bare energy spectrum is strong, the energy levels are calculated using Fal'kovskii's adiabatic approximation for multiband systems. When the quantum dot material has an inverted band gap with respect to the host, the low-energy states within the fundamental gap are shown to arise.

The model for finite-range correlated compositional disorder is proposed, and the calculation of the energy domain of the exciton localization in alloy quantum well is carried out. The approach suggests an interpolation scheme between an uncorrelated and a finite-range correlated disorder and describes experimental data on excitonic pholuminescence in group III-nitride alloy quantum wells.

DST was ascertained to have a high sensitivity in virtually all patients with tuberculosis and a positive reaction was first noted in the infected. With stabilization and regression, the response to DST was much less pronounced than that in clinical and primary infection (that to the Mantoux test being more evident). DST showed its use as a marker of active tuberculosis not only in its local forms, but also in latent tuberculous infection. This makes it possible to apply DST when preventive treatment is performed. The agent may be used to monitor the progress of treatment. DST has a high specificity--healthy individuals had a negative response to DST while the Mantoux test was positive in many cases. The high specificity of DST was suggested by the fact that the persons vaccinated with (this caused BCG ostitis) had a negative reaction to DST while the Mantoux test was positive in all cases BCG-vaccinated BCG. The findings warrant the use of DST for the differential diagnosis of tuberculosis and BCG-associated complications and the possibility of differentiating postvaccinal and infection allergy in children and adolescents.

A new reagent for a skin test given the name Diaskintest has been designed for the screening diagnosis of tuberculosis and preclinical and clinical trials conducted. Preclinical trials were carried out on 315 laboratory animals (guinea-pigs, albino mice). The reagent Diaskintest was ascertained to be nontoxic, to have no sensitizing properties, to be safe and specific, and to induce no positive reactions in BCG-vaccinated animals and healthy guinea-pigs. Its specific activity was comparable with that of the national reference--purified tuberculin PPD-L-2. With progression of tuberculous lesions, the guinea-pigs showed higher responses to Diaskintest dilution and the BCG-vaccinated animals lacked responses to Diaskintest with increased delayed type hypersensitivity. The clinical trial was permitted by the Federal Service for Surveillance in Health Care and Social Development of the Russian Federation. Clinical trials were conducted in 150 persons. The safety, specificity, sensitivity of Diaskintest were first examined in the clinical studies and its action was compared with the results of tuberculin skin test (Mantoux test) with 2 TE of PPD L-2. Diaskintest was ascertained to be highly sensitive when given in a dose of 0.2 microg in 0.1 ml. In patients with active tuberculosis and new cases of Mycobacterium tuberculosis infection, the agent induced a positive skin reaction (a papule of more than 10 mm) in 98-100% of cases (p0.05). The agent caused no reaction associated with BCG vaccination. The specificity of the test was 93-100% with 95% significance. The rate of overexuberant reactions (vesicular necrotic changes, lymphangitis, and lymphadenitis) was 4-14% with 95% significance. Tuberculosis patients with significant immunopathological disorders might have no skin sensitivity to Diaskintest, as to PPD L-2 (a negative test). The findings substantiate the use of Diaskintest for mass epidemiological surveys for the differential diagnosis of tuberculosis and BCG vaccination-associated complications. The agent may be also used to evaluate the activity of the process in patients with tuberculosis and the efficiency of treatment in combination with other methods and to make a differential diagnosis of tuberculosis.

We present an explanation of recently observed giant magnetic moment and room-temperature ferromagnetism in the dielectric GaN doped with Gd. Our approach uses the polarization mechanism of exchange interaction, which occurs if the d-level of Gd appears in the bandgap close to the valence band edge. Calculated ferromagnetic critical temperature and the value of the magnetic moment well correspond to experimental findings., Comment: 9 pages, 3 figures submitted to Applied Physics Letters

Criteria for clinical cure have been analyzed and the efficiency of treatment evaluated in patients with respiratory tuberculosis in Moscow. If today's official criteria for the efficiency of treatment have been ascertained to preserve in treating the first detected patients, a phthisiological service will completely lose an objective control of this section of work in several years. The only criterion that gives some idea of the results of treatment in first detected patients is currently to transfer them to dispensary register group III. However, when the results of interim treatment stages are unknown, conditions are created for utter arbitrariness in the time of the transfer (this happens at present). It is necessary to hold today's existing major criteria (cessation of bacterial isolation and closure of decay cavities) for evaluating the efficiency of treatment in first detected patients (who are largely inpatients) and to add one more criterion (disappearance of Xray signs of active tuberculosis manifestations); moreover, the magnitude of major or minor residual tuberculous changes should be, of course, taken into account after a basic course of chemotherapy.

The paper describes the follow-up and treatment of patients with tuberculosis concurrent with HIV infection in Moscow in 2004-2005. Major epidemiological parameters, such as morbidity, mortality, and prevalence of this comorbidity, are given. Analysis of these indices suggests that the epidemic situation associated with tuberculosis concurrent with HIV infection became worse in the past 2 years. As compared with 2004, in 2005 the number of such patients increased from 294 to 445, including that of first detected patients rose from 123 to 174. In this group of patients, there was a preponderance of young males aged 29 to 39 years. Most patients with this pathology suffered from drug addiction and alcoholism and other concomitant diseases. The bulk of them were unemployed and disabled. In the HIV-infected, the clinical forms of tuberculosis were severe with a predominance of acute and disseminated processes; the rate of drug resistance, including multidrug resistance, was high, which made treatment difficult and resulted in high mortality.

Tunnel spin polarization in a piezoelectric AlGaN/GaN double barrier structure is calculated. It is shown that the piezoelectric field and the spontaneous electrical polarization increase an efficiency of the tunnel spin injection. The relation between the electrical polarization and the spin orientation allows engineering a zero magnetic field spin injection manipulating the lattice-mismatch strain with an Al-content in the barriers., 13 pages, 6 figures

The temperature dependence of the nonequilibrium carriers lifetime has been deduced from the measurement of the photocurrent response in InAs/GaSb superlattices. Based on the temperature dependence of the responsivity and modeling of the transport parameters we have found that the carrier lifetime weakly depends on temperature in the high-temperature region. This indicates the temperature dependence of the Auger recombination rate with no threshold that differs it from that in the bulk material and can be attributed to the interface-induced suppression of the Auger recombination in thin quantum wells.

The indirect exchange interaction between magnetic impurities localized in a graphene plane is considered theoretically, with the influence of intrinsic spin-orbit interaction taken into account. Such an interaction gives rise to an energy gap at the Fermi level, which makes the usual RKKY model not applicable. The results show that the effective indirect exchange interaction is described by a range function which decays exponentially with the distance between magnetic moments. The interaction is also shown to depend on whether the two localized moments belong to the same sublattice or are located in two different sublattices., 5 pages, 1 figure

Spin-orbit coupling is studied using the quantum interference corrections to conductance in AlxGa1�xN / AlN/ GaN two-dimensional electron systems where the carrier density is controlled by the persistent photoconductivity effect. All the samples studied exhibit a weak antilocalization feature with a spin-orbit field of around 1.8 mT. The zero-field electron spin splitting energies extracted from the weak antilocalization measurements are found to scale linearly with the Fermi wave vector ESS =2 kf with an effective linear spin-orbit coupling parameter = 5.5 10 �13 eV m. The spin-orbit times extracted from our measurements varied from 0.74 to 8.24 ps within the carrier density range of this experiment.

The mean-field-approximation and percolation models of ferromagnetism are extended to account for the mixed valence and mixed magnetic state of a transition-metal impurity. The approach allows calculating the ferromagnetic critical temperature related to the Fermi-level position in the band gap of III-nitride semiconductors. The results of generalized percolation theory qualitatively agree with the first-principles calculations.

The results of examination of 84 patients with tuberculosis of the central nervous system were used to make comparative clinical and laboratory studies. They revealed that lymphocytosis detected in the cerebrospinal fluid (CF), particularly the prevalence of lymphocytes (more than 50%), and decreased levels of chlorides in the cytogram were of value in the comprehensive diagnosis of tuberculous meningitis. The detection of CF Mycobacterium tuberculosis (MBT) (applying the whole currently available set of methods) is an absolute criterion for the diagnosis of tuberculous meningitis (however, with, unfortunately, few number positive results). The detection of mycobacterial DNA, antigens, and tuberculosis antibodies is an impotent component of a diagnostic complex for tuberculous meningitis. The determination of cytosis, protein, glucose, chlorides, lymphocytic subpopulations, soluble gamma-interferon mediators, mycobacteria, DNA, MBT antigens, and tuberculosis antibodies in SF is essential in treating tuberculous meningitis.

The correlations between the time series of weather values of sociodemographic, socioeconomic, and epidemiological parameters of tuberculosis (death rates) in the 20th century were studied. Analysis of population indices confirmed the association of migratory processes and the intensity of the tuberculosis epidemic situation, as well as the significance of these processes for Moscow, the necessity of their notification for assessing the sociodemographic situation to plan tuberculosis-controlling measures. The study has indicated that there is a relationship of the salary/wage that determines the income of the bulk of the population to tuberculosis mortality rates and that regulation of a migratory process, population density, and improvement of living conditions are of considerable importance in the prevention of this disease. Comparative analysis of the data in the periods when the whole contemporary rather effective complex of tuberculosis-controlling measures (1953-2000) and when the above complex were only formed (1910-1953) has demonstrated the economic efficiency of the above measures. It is stated that the system of sociomedical protective measures is a real factor that may rather effectively withstand the poor social conditions promoting the spread of tuberculosis.

The magnetoquantum and quantum-interference effects of two-dimensional hole gas in Si/SiGe-based heterostructures with Si 1−X Ge X quantum wells were studied in the temperature range 0.35 – 70K in a magnetic field up to 11T. In high magnetic fields (B > 1.5T) the magnetic field dependencies of the samples resistances exhibit the Shubnikov-de Haas oscillations. The positive growth and maximum of magnetoresistances are observed in weak magnetic fields limit (B < 0.1T), which can be attributed to the influence of weak localization of the charge carriers when the inelastic scattering time τ φ and spin orbit scattering time τSO have close values. It is shown that in the heterostructures studied splitting of the spin states occurs due to the influence of the perturbing potential (Rashba mechanism). The corresponding quantum times and spin splitting values are calculated.

The Rashba spin-orbit splitting parameter has been calculated in wurtzite GaN/AlGaN heterostructures. Despite the fact that wide-bandgap semiconductors are expected to have a smaller spin-orbit coupling parameter than that in InGaAs-based III-V materials, the electron spin-split energy in GaN/AlGaN heterostructure is predicted to have the same order of magnitude, due to the strong polarization field at the interface and polarization-induced doping. This, taken together with the existence of room-temperature ferromagnetism in GaN(Mn), could make the GaN-based material system competitive in spintronic applications.

The authors study the energy spectrum of a single spherical quantum dot of narrow-gap IV-VI material embedded within a host IV-VI material of different bandgap. The calculations of the energy levels as a function of the dot radius are performed. When the anisotropy is strong, the energy spectrum is investigated using Fal'kovskii's adiabatic approximation for multiband systems. When the quantum dot material has an inverted bandgap with respect to the host, low-energy edge states are shown to exist.