292 research outputs found
Registration of CBS Effects from Wedge-shaped Samples Containing Particles of Alumina
The paper looks at recent results of research dealing with a coherent backscattering (CBS) on the particles of alumina. It was developed a system of registration of CBS with a tunable dynamic sample. During the experiment the transport mean free path over the width of the peak of angular profile of signal intensity of CBS was determined. Moreover, new scientific data about the CBS’s profiles from randomly inhomogeneous environments were obtained
New and rare lichens for Russia and the Caucasus from high mountainous Dagestan (East Caucasus)
Five species of lichenized ascomycetes are reported from high mountainous Dagestan. Acarospora laqueata, Lecania ochronigra and Protoparmelia placentiformis are new to Russia and the Caucasus (the last two). Anamylopsora pulcherrima is the first record of the genus and species for the North Caucasus. Buellia centralis is the first record for the Caucasus and second for Russia. Our records considerably extended information about geography and ecology of presented species especially the very rare species Buellia centralis, Lecania ochronigra and Protoparmelia placentiformis. The characteristic features of specimens with information of their morphology, anatomy, ecology and world distribution are given
Inverse Solvability and Security with Applications to Federated Learning
We introduce the concepts of inverse solvability and security for a generic
linear forward model and demonstrate how they can be applied to models used in
federated learning. We provide examples of such models which differ in the
resulting inverse solvability and security as defined in this paper. We also
show how the large number of users participating in a given iteration of
federated learning can be leveraged to increase both solvability and security.
Finally, we discuss possible extensions of the presented concepts including the
nonlinear case
Monitoring vibrations and microdisplacement for "pin on disc" tribology studies
The paper studies the example of applying accelerometers to evaluate tribocoupling vibration characteristics and verification methods in the testing system "pin on disc". Microelectromechanical systems (MEMS) intended for operation over a wide static and spectral ranges were applied. Accelerator spatial track recovery was implemented through the double integration algorithm. In the course of the work, the vibrations occurring through the friction between fluorocarbon and brass alloy LS59-1 under the conditions of dry friction were studied
Interband electron Raman scattering in a quantum wire in a transverse magnetic field
Electron Raman scattering (ERS) is investigated in a parabolic semiconductor
quantum wire in a transverse magnetic field neglecting by phonon-assisted
transitions. The ERS cross-section is calculated as a function of a frequency
shift and magnetic field. The process involves an interband electronic
transition and an intraband transition between quantized subbands. We analyze
the differential cross-section for different scattering configurations. We
study selection rules for the processes. Some singularities in the Raman
spectra are found and interpreted. The scattering spectrum shows
density-of-states peaks and interband matrix elements maximums and a strong
resonance when scattered frequency equals to the "hybrid" frequency or
confinement frequency depending on the light polarization. Numerical results
are presented for a GaAs/AlGaAs quantum wire.Comment: 8 pages, 5 figure
Monitoring vibrations and microdisplacement for "pin on disc" tribology studies
The paper studies the example of applying accelerometers to evaluate tribocoupling vibration characteristics and verification methods in the testing system "pin on disc". Microelectromechanical systems (MEMS) intended for operation over a wide static and spectral ranges were applied. Accelerator spatial track recovery was implemented through the double integration algorithm. In the course of the work, the vibrations occurring through the friction between fluorocarbon and brass alloy LS59-1 under the conditions of dry friction were studied
Influence of dispersing additive on asphaltenes aggregation in model system
The work is devoted to investigation of the dispersing additive influence on asphaltenes aggregation in the asphaltenes-toluene-heptane model system by photon correlation spectroscopy method. The experimental relationship between the onset point of asphaltenes and their concentration in toluene has been obtained. The influence of model system composition on asphaltenes aggregation has been researched. The estimation of aggregative and sedimentation stability of asphaltenes in model system and system with addition of dispersing additive has been given
Risk of acquired drug resistance during short-course directly observed treatment of tuberculosis in an area with high levels of drug resistance.
BACKGROUND: Data on the performance of standardized short-course directly observed treatment (DOTS) of tuberculosis (TB) in areas with high levels of drug resistance and on the potential impact of DOTS on amplification of resistance are limited. Therefore, we analyzed treatment results from a cross-sectional sample of patients with TB enrolled in a DOTS program in an area with high levels of drug resistance in Uzbekistan and Turkmenistan in Central Asia. METHODS: Sputum samples for testing for susceptibility to 5 first-line drugs and for molecular typing were obtained from patients starting treatment in 8 districts. Patients with sputum smear results positive for TB at the end of the intensive phase of treatment and/or at 2 months into the continuation phase were tested again. RESULTS. Among 382 patients with diagnoses of TB, 62 did not respond well to treatment and were found to be infected with an identical Mycobacterium tuberculosis strain when tested again; 19 of these patients had strains that developed new or additional drug resistance. Amplification occurred in only 1.2% of patients with initially susceptible or monoresistant TB strains, but it occurred in 17% of those with polyresistant strains (but not multidrug-resistant strains, defined as strains with resistance to at least isoniazid and rifampicin) and in 7% of those with multidrug-resistant strains at diagnosis. Overall, 3.5% of the patients not initially infected with multidrug-resistant TB strains developed such strains during treatment. Amplification of resistance, however, was found only in polyresistant Beijing genotype strains. CONCLUSIONS: High levels of amplification of drug resistance demonstrated under well-established DOTS program conditions reinforce the need for implementation of DOTS-Plus for multidrug-resistant TB in areas with high levels of drug resistance. The strong association of Beijing genotype and amplification in situations of preexisting resistance is striking and may underlie the strong association between this genotype and drug resistance
On a factorization of second order elliptic operators and applications
We show that given a nonvanishing particular solution of the equation
(divpgrad+q)u=0 (1) the corresponding differential operator can be factorized
into a product of two first order operators. The factorization allows us to
reduce the equation (1) to a first order equation which in a two-dimensional
case is the Vekua equation of a special form. Under quite general conditions on
the coefficients p and q we obtain an algorithm which allows us to construct in
explicit form the positive formal powers (solutions of the Vekua equation
generalizing the usual powers of the variable z). This result means that under
quite general conditions one can construct an infinite system of exact
solutions of (1) explicitly, and moreover, at least when p and q are real
valued this system will be complete in ker(divpgrad+q) in the sense that any
solution of (1) in a simply connected domain can be represented as an infinite
series of obtained exact solutions which converges uniformly on any compact
subset of . Finally we give a similar factorization of the operator
(divpgrad+q) in a multidimensional case and obtain a natural generalization of
the Vekua equation which is related to second order operators in a similar way
as its two-dimensional prototype does
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