The effect of the formation of deep minima in frequency characteristics of photon density waves (PDWs) during their propagation in scattering media with different optical characteristics has been studied by statistical Monte Carlo modeling. The simulation was performed for the Henyey-Greenstein scattering phase function with the anisotropy factor value varying in the range of 0-0.93.
View Article and Find Full Text PDFAn up to 15 T pulsed magnetic field generator in a volume of a few cubic centimeters has been developed for experiments with magnetized laser plasma. The magnetic field is created by a pair of coils placed in a sealed reservoir with liquid nitrogen, installed in a vacuum chamber with a laser target. The bearing body provides the mechanical strength of the system both in the case of co-directional and oppositely connected coils.
View Article and Find Full Text PDFStatistical modeling of pulsed frequency responses of the light field radiance by an isotropic point source was performed by Monte Carlo technique. Scattering properties of the medium were simulated by the Henyey-Greenstein phase function with different anisotropy factor values. Angular distributions of the pulsed field and amplitudes of the photon density waves in a certain range of parameters were shown to have a qualitatively different character for media with quasi-isotropic and strongly anisotropic scattering.
View Article and Find Full Text PDFThe frequency characteristics of spherical photon density waves excited in media with different degrees of scattering anisotropy are studied. Statistical modeling of the frequency and phase responses of the spatial irradiance of the light field emitted by a point-sized isotropic source were performed employing the Monte Carlo technique. The scattering anisotropy of the medium was determined by the Henyey-Greenstein phase function with different values of the mean scattering cosine.
View Article and Find Full Text PDFThe spatial-angular and temporal characteristics of the radiance of the light field emitted by a nonstationary point isotropic source in sea water are studied. Using the Monte Carlo method, we calculated the pulse transfer functions and frequency responses of the angular radiance distributions at various distances from the source. Particular integral characteristics of the angular radiance distributions are estimated.
View Article and Find Full Text PDFIntroduction: Russia took part in the multicenter population-based study (Europe) and included 6.8% adult patients with newly diagnosed chronic myeloid leukemia (CML). The objective of this study was to analyze the mortality in the Russian cohort of patients with newly diagnosed CML in the EUTOS PBS observational study.
View Article and Find Full Text PDFThe parameters of an echo signal from the underwater lidar are studied for the case of modulation of a probing pulse by a high frequency signal with a frequency linearly varying with time. The analysis is based on the statistical Monte Carlo simulations of the frequency and phase responses of a signal propagating along the emitter-water-reflector-water-receiver path and an analytical representation of the signal as a pulse described by a Gaussian function with intrapulse modulation. Delays and pulse shape changes caused by temporal dispersion of the photon-density waves are estimated.
View Article and Find Full Text PDFCharacteristics of different underwater imaging systems are compared based on the results of Monte Carlo simulations of light transport in the sea water. The consideration includes systems with continuous-wave illumination, modulated illumination, pulsed systems with time gating detection, and hybrid systems with probing pulse modulated at high frequency. To generalize the study, the ratio of SNRs of different systems when imaging a sinusoidal test pattern is analyzed.
View Article and Find Full Text PDFBackscatter signal formation in underwater lidar systems is studied and temporal and frequency characteristics are analyzed using the Monte Carlo technique. Both frequency and phase responses of the backscattered signal demonstrate similar dependencies, showing stronger frequency dependence in the high-frequency range. The beats of the frequency response due to dephasing of corresponding spectral harmonics are shown in the high-frequency range.
View Article and Find Full Text PDFOptical transfer functions of underwater imaging systems employing narrow pulses or sinusoidally modulated beams for image formation are studied. A modified Monte Carlo technique allowing for direct statistical modeling of these functions accounting for temporal dispersion is proposed and implemented. The optical transfer functions are calculated for various modulation frequencies of the illumination beam and for the case of pulsed illumination.
View Article and Find Full Text PDFThe structure of a light field in sea water excited by a unidirectional point-sized pulsed source is studied by Monte Carlo technique. The pulse shape registered at the distances up to 120 m from the source on the beam axis and in its axial region is calculated with a time resolution of 1 ps. It is shown that with the increase of the distance from the source the pulse splits into two parts formed by components of various scattering orders.
View Article and Find Full Text PDFA 263 GHz continuous-wave (CW) gyrotron was developed at the IAP RAS for future applications as a microwave power source in Dynamic Nuclear Polarization / Nuclear magnetic resonance (DNP/NMR) spectrometers. A new experimental facility with a computerized control was built to test this and subsequent gyrotrons. We obtained the maximum CW power up to 1 kW in the 15 kV/0.
View Article and Find Full Text PDFThe effects of GSTM1 and GSTT1 gene deletion ("zero") polymorphisms on the risk of chronic myeloid leukemia development and progress and on response to imatinib monotherapy were studied in the representatives of the Russian nationality in the Vyatka region of Russia. Homozygotic carriership of GSTT1 "zero" allele was associated with a 3.66 times higher risk of chronic myeloid leukemia development in residents of the Vyatka region (OR=3.
View Article and Find Full Text PDFAim: To assess the main epidemiological characteristics of chronic myeloid leukemia (CML) in the Russian Federation.
Subjects And Methods: A planned epidemiological prospective study was conducted in 2009-2012 in 6 Russian regions with the total number of 10.1 million inhabitants, which notified all new CML cases.
Rev Sci Instrum
July 2012
The dual-frequency gyrotron with fast 2% frequency sweep at about 28 GHz is designed to power an electron cyclotron resonance ion source (ECRIS). Operation with an output power of up to 10 kW in CW mode and efficiency of 20% was demonstrated at both frequencies. Frequency manipulation has a characteristic time of about 1 ms and is based on magnetic field variation with an additional low-power coil.
View Article and Find Full Text PDFThe influence of surface waves and multiple scattering in water on the parameters of light pulses from an airborne source is studied. The contributions of various mechanisms to variations in delay of pulse and its variance are estimated. It is shown that waves make the main contribution to these values at small depths.
View Article and Find Full Text PDFWe investigate the possibility of using the water-backscattered radiation from a bottom sounding airborne imaging light detection and ranging (lidar) system to determine the surface slope at the point where the laser beam intersects the surface. We show that the refraction angle of the beam can be determined using receivers whose sensitivities vary linearly over their field of view. Equations are derived to estimate the statistical mean and variance values of this refracted angle.
View Article and Find Full Text PDFTo cover a so-called terahertz gap in available sources of coherent electromagnetic radiation, the gyrotron with a pulsed solenoid producing up to a 40 T magnetic field has been designed, manufactured, and tested. At a 38.5 T magnetic field, the gyrotron generated coherent radiation at 1.
View Article and Find Full Text PDF