The Linear Inverse Problem of Gravimetry and Magnetometry with Iterative Formulas of Analogs of Wiener-Kalman Filters

Усовершенствованы итерационные методы решения обратных линейных задач гравиметрии и магнитометрии на основе аналогов фильтров Винера–Калмана для двух интерпретационных моделей, использующих разделение карты поля на два массива четных и нечетных профилей. Приведены новые итерационные формулы, обеспечивающие, в отличие от известных методов, устойчивое и геологически содержательное решение с любых начальных условий без предварительного решения другими методами. Это дает два близких решения, независимых от решений обратной задачи  другими методами. Приведены примеры практической реализации метода для магнитометрии в рудном районе на Украинском щите.The article presents the improved iterative methods of solution of the inversion linear problems of gravimetry and magnetometry based on analogs of Wiener-Kalman filters applied to two interpretation models obtained in result of subdivision of the field grid on two sub grids containing even and odd profiles respectively. The new iterative formulas provide stable and geologically true interpretation with arbitrary initial conditions and without usage of decisions preliminarily obtained with other methods. It gives two close decisions, independent of solutions of the inverse problem achieved with other methods. Examples of practical implementation of method for processing and interpretation of magnetic data obtained at the area of iron ore deposit, Ukraine, are given

Thyroid cancer risk in Belarus among children and adolescents exposed to radioiodine after the Chornobyl accident

BACKGROUND: Previous studies showed an increased risk of thyroid cancer among children and adolescents exposed to radioactive iodines released after the Chornobyl (Chernobyl) accident, but the effects of screening, iodine deficiency, age at exposure and other factors on the dose-response are poorly understood. METHODS: We screened 11 970 individuals in Belarus aged 18 years or younger at the time of the accident who had estimated (131)I thyroid doses based on individual thyroid activity measurements and dosimetric data from questionnaires. The excess odds ratio per gray (EOR/Gy) was modelled using linear and linear-exponential functions. RESULTS: For thyroid doses \u3c5 \u3eGy, the dose-response was linear (n=85; EOR/Gy=2.15, 95% confidence interval: 0.81-5.47), but at higher doses the excess risk fell. The EOR/Gy was significantly increased among those with prior or screening-detected diffuse goiter, and larger for men than women, and for persons exposed before age 5 than those exposed between 5 and 18 years, although not statistically significant. A somewhat higher EOR/Gy was estimated for validated pre-screening cases. CONCLUSION: 10-15 years after the Chornobyl accident, thyroid cancer risk was significantly increased among individuals exposed to fallout as children or adolescents, but the risk appeared to be lower than in other Chornobyl studies and studies of childhood external irradiation

The Flux-Line Lattice in Superconductors

Magnetic flux can penetrate a type-II superconductor in form of Abrikosov vortices. These tend to arrange in a triangular flux-line lattice (FLL) which is more or less perturbed by material inhomogeneities that pin the flux lines, and in high-$T_c$ supercon- ductors (HTSC's) also by thermal fluctuations. Many properties of the FLL are well described by the phenomenological Ginzburg-Landau theory or by the electromagnetic London theory, which treats the vortex core as a singularity. In Nb alloys and HTSC's the FLL is very soft mainly because of the large magnetic penetration depth: The shear modulus of the FLL is thus small and the tilt modulus is dispersive and becomes very small for short distortion wavelength. This softness of the FLL is enhanced further by the pronounced anisotropy and layered structure of HTSC's, which strongly increases the penetration depth for currents along the c-axis of these uniaxial crystals and may even cause a decoupling of two-dimensional vortex lattices in the Cu-O layers. Thermal fluctuations and softening may melt the FLL and cause thermally activated depinning of the flux lines or of the 2D pancake vortices in the layers. Various phase transitions are predicted for the FLL in layered HTSC's. The linear and nonlinear magnetic response of HTSC's gives rise to interesting effects which strongly depend on the geometry of the experiment.Comment: Review paper for Rep.Prog.Phys., 124 narrow pages. The 30 figures do not exist as postscript file

Measurements on rotating ion cyclotron range of frequencies induced particle fluxes in axisymmetric mirror plasmas

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