Application of a wavelet technique for the detection of earthquake signatures in the geomagnetic field

We developed an algorithm especially adapted to <i>single-station </i>wavelet detection of geomagnetic events, which precede or accompany the earthquakes. The detection problem in this situation is complicated by a great variability of earthquakes and accompanied phenomena, which aggravates finding characteristic features of the events. Therefore we chose to search for the characteristic features of both &quot;disturbed&quot; intervals (containing earthquakes) and &quot;quiet&quot; recordings. In this paper we propose an algorithm for solving the problem of detecting the presence of signals produced by an earthquake via analysis of its signature against the existing database of magnetic signals. To achieve this purpose, we construct the magnetic signature of certain earthquakes using the distribution of the energies among blocks, which consist of wavelet packet coefficients

Magnetically induced spin-dependent photoemission from p-GaAs(Cs,O) into vacuum

A spin-dependent emission of optically oriented electrons from p-GaAs(Cs,O) into vacuum was experimentally observed in a magnetic field normal to the surface. This phenomenon is explained within the model which takes into account the jump in the electron g factor at the semiconductor-vacuum interface. Due to this jump, the effective electron affinity on the semiconductor surface depends on the mutual direction of optically oriented electron spins and the magnetic field, resulting in the spin-dependent photoemission. It is demonstrated that the observed effect can be used for the determination of spin diffusion length in semiconductors.Comment: 7 pages, 6 figures, published versio

Controlling the spin orientation of photoexcited electrons by symmetry breaking

We study reflection of optically spin-oriented hot electrons as a means to probe the semiconductor crystal symmetry and its intimate relation with the spin-orbit coupling. The symmetry breaking by reflection manifests itself by tipping the net-spin vector of the photoexcited electrons out of the light propagation direction. The tipping angle and the pointing direction of the net-spin vector are set by the crystal-induced spin precession, momentum alignment and spin-momentum correlation of the initial photoexcited electron population. We examine non-magnetic semiconductor heterostructures and semiconductor/ferromagnet systems and show the unique signatures of these effects.Comment: 4 pages, 3 figures, resubmitte

Kramers-Kronig constrained variational analysis of optical spectra

A universal method of extraction of the complex dielectric function $\epsilon(\omega)=\epsilon_{1}(\omega)+i\epsilon_{2}(\omega)$ from experimentally accessible optical quantities is developed. The central idea is that $\epsilon_{2}(\omega)$ is parameterized independently at each node of a properly chosen anchor frequency mesh, while $\epsilon_{1}(\omega)$ is dynamically coupled to $\epsilon_{2}(\omega)$ by the Kramers-Kronig (KK) transformation. This approach can be regarded as a limiting case of the multi-oscillator fitting of spectra, when the number of oscillators is of the order of the number of experimental points. In the case of the normal-incidence reflectivity from a semi-infinite isotropic sample the new method gives essentially the same result as the conventional KK transformation of reflectivity. In contrast to the conventional approaches, the proposed technique is applicable, without readaptation, to virtually all types of linear-response optical measurements, or arbitrary combinations of measurements, such as reflectivity, transmission, ellipsometry {\it etc.}, done on different types of samples, including thin films and anisotropic crystals.Comment: 10 pages, 7 figure

Terahertz radiation driven chiral edge currents in graphene

We observe photocurrents induced in single layer graphene samples by illumination of the graphene edges with circularly polarized terahertz radiation at normal incidence. The photocurrent flows along the sample edges and forms a vortex. Its winding direction reverses by switching the light helicity from left- to right-handed. We demonstrate that the photocurrent stems from the sample edges, which reduce the spatial symmetry and result in an asymmetric scattering of carriers driven by the radiation electric field. The developed theory is in a good agreement with the experiment. We show that the edge photocurrents can be applied for determination of the conductivity type and the momentum scattering time of the charge carriers in the graphene edge vicinity.Comment: 4 pages, 4 figure, additional Supplemental Material (3 pages, 1 figure

Self‐consistent modeling of the large‐scale distortions in the geomagnetic field during the 24–27 September 1998 major magnetic storm

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94715/1/jgra17531.pd

Positron-emission tomography–based staging reduces the prognostic impact of early disease progression in patients with follicular lymphoma

Background: Previous studies reported that early progression of disease (POD) after initial therapy predicted poor overall survival (OS) in patients with follicular lymphoma (FL). Here, we investigated whether pre-treatment imaging modality had an impact on prognostic significance of POD. Methods: In this retrospective study, we identified 1088 patients with grade I–IIIA FL; of whom, 238 patients with stage II–IV disease were initially treated with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP), and 346 patients were treated with rituximab-based chemotherapy. Patients (N = 484) from the FOLL05 study served as an independent validation cohort. We risk-stratified patients based on pre-treatment radiographic imaging (positron-emission tomography [PET] versus computed tomography [CT]) and early POD status using event-defining and landmark analyses. A competing risk analysis evaluated the association between early POD and histologic transformation. Results: In the discovery cohort, patients with POD within 24 months (PFS24) of initiating R-CHOP therapy had a 5-year OS of 57.6% for CT-staged patients compared with 70.6% for PET-staged patients. In the validation cohort, the 5-year OS for patients with early POD was 53.9% and 100% in CT- and PET-staged patients, respectively. The risk of histologic transformation in patients whose disease progressed within one year of initiating therapy was higher in CT-staged patients than in PET-staged patients (16.7% versus 6.3%, respectively), which was associated with a 9.7-fold higher risk of death. Conclusion: In FL, pre-treatment PET staging reduced the prognostic impact of early POD compared with CT staging. Patients with early POD and no histologic transformation have an extended OS with standard therapy

Криохирургия очаговых поражений печени

The results of cryosurgical treatment of 339 patients with various focal liver diseases are presented. The experience of using cryosurgical equipment designed and manufactured in the Tomsk Hepatological Center in the surgery of focal liver diseases is analyzed. The application of inventive instruments in the liver resection leads to a decrease in the intraoperative blood loss down to 30- 40% and favors the reduction of backsets, because the cryodestruction of liver stump after resection leads to the destruction of rest parts of parasitic tissue in the surgical zone. The use of cryosurgical techniques lowers the number of deaths down to 4.42%.Представлены результаты лечения 339 больных после криохирургических операций на печени при различных очаговых поражениях этого органа. Проанализирован опыт применения в хирургии очаговых поражений печени оригинальной криохирургической техники, созданной в Томском гепатологическом центре. Применение инструментов оригинальной конструкции во время резекции печени приводит к снижению интраоперационной кровопотери до 30—40%, а также способствует уменьшению количества рецидивов заболевания, поскольку криодеструкция культи печени после резекции ведет к разрушению оставленных участков паразитарной ткани в зоне операции. Использование криохирургических методик позволяет снизить частоту летальных исходов до 4,42%