[Patterns of structural and functional changes in the retina and choroid in acute posterior multifocal placoid pigment epitheliopathy]. / Zakonomernosti strukturno-funktsional'nykh izmenenii setchatki i khorioidei pri ostroi zadnei mul'tifokal'noi plakoidnoi pigmentnoi epiteliopatii.

PURPOSE: The study analyzes the patterns of pathological changes in the retina and choroid in acute posterior multifocal placoid pigmented epitheliopathy (APMPPE). MATERIAL AND METHODS: The results of the examination of two patients with bilateral APMPPE were analyzed retrospectively. The examination had included visometry, tonometry, static perimetry, autofluorescence, optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA). RESULTS: The analysis revealed signs of the inflammatory nature of the choriocapillary vascular wall lesion with the development of their local obstruction and, consequently, local ischemia of the retinal pigment epithelium (RPE) and the outer layers of the retina in the acute period. At the same time, partial destruction of the ellipsoid zone, uneven hyperreflectivity of the RPE with local areas of its elevation and impaired connection with photoreceptors were revealed. The subsequent restoration of choriocapillaris perfusion was accompanied by significant restoration of the functional and structural state of the RPE over a larger area, as well as partial restoration of the ellipsoid zone of the retina. Two years after the onset of the disease, separate areas of defects of the RPE and the outer retina were observed, coinciding in localization with zones of severe circulatory deficiency at the level of choriocapillaris in the acute stage. CONCLUSION: According to the results of multimodal imaging, choriocapillaritis is the initial link in the pathogenesis of APMPPE. The change in RPE and the outer retina is secondary to the local ischemic zones due to choriocapillaris nonperfusion. The nature of RPE change over a larger area manifests as a functional structural disorder, with the potential for recovery in case of choriocapillaris reperfusion.

Cleaning of first mirrors in ITER by means of radio frequency discharges.

First mirrors of optical diagnostics in ITER are subject to charge exchange fluxes of Be, W, and potentially other elements. This may degrade the optical performance significantly via erosion or deposition. In order to restore reflectivity, cleaning by applying radio frequency (RF) power to the mirror itself and thus creating a discharge in front of the mirror will be used. The plasma generated in front of the mirror surface sputters off deposition, restoring its reflectivity. Although the functionality of such a mirror cleaning technique is proven in laboratory experiments, the technical implementation in ITER revealed obstacles which needs to be overcome: Since the discharge as an RF load in general is not very well matched to the power generator and transmission line, power reflections will occur leading to a thermal load of the cable. Its implementation for ITER requires additional R&D. This includes the design of mirrors as RF electrodes, as well as feeders and matching networks inside the vacuum vessel. Mitigation solutions will be evaluated and discussed. Furthermore, technical obstacles (i.e., cooling water pipes for the mirrors) need to be solved. Since cooling water lines are usually on ground potential at the feed through of the vacuum vessel, a solution to decouple the ground potential from the mirror would be a major simplification. Such a solution will be presented.

[Modern trends in surgery of gastrointestinal tract tumors].

Development of cancer surgery in recent decades occurs on a background of continuing scientific and technical progress. New technologies after the completion of clinical trials maximally quickly are included in the routine practice of specialized medical centers. At present an escalation of indications for extensive advanced and combined operations in locally advanced and even metastatic tumors goes in parallel with the introduction of minimally invasive interventions, search categories of patients, for whom the radicalism of treatment can be achieved without significant surgical aggression. The study of modern trends of this process will allow seeing the promising areas of scientific research, assuming the image of the future of surgery for cancer.

[Laparoscopic surgery for rectal cancer: a literature review and own experience].

The main treatment option for rectal cancer is surgery, which "gold standard" is the total mesorectumectomy. There are presented literature review and the results of own research devoted to comparative analysis of outcomes of laparoscopic and open total mesorectumectomy. Current data and own experience show the oncological adequacy and safety of laparoscopic approach however the controversy of some results reveal the necessity of further investigation.

Dislocation dynamics during plastic deformations of complex plasma crystals.

The internal structures of most periodic crystalline solids contain defects. This affects various important mechanical and thermal properties of crystals. Since it is very difficult and expensive to track the motion of individual atoms in real solids, macroscopic model systems, such as complex plasmas, are often used. Complex plasmas consist of micrometer-sized grains immersed into an ion-electron plasma. They exist in solidlike, liquidlike, and gaseouslike states and exhibit a range of nonlinear and dynamic effects, most of which have direct analogies in solids and liquids. Slabs of a monolayer hexagonal complex plasma were subjected to a cycle of uniaxial compression and decompression of large amplitudes to achieve plastic deformations, both in experiments and simulations. During the cycle, the internal structure of the lattice exhibited significant rearrangements. Dislocations (point defects) were generated and displaced in the stressed lattice. They tended to glide parallel to their Burgers vectors under load. It was found that the deformation cycle was macroscopically reversible but irreversible at the particle scale.

Scale-free behavior of a 2D complex plasma during rapid cooling.

Experimental evidence is presented for a scale-free transition from an unordered to an ordered state in a 2D complex plasma that differs from the KTHNY theory of phase transitions in 2D systems. The transition is characterized by the formation and growth of ordered domains. A fractal relationship is found between the domain areas and domain boundary lengths, which can be explained by a recent theoretical model. The experimental findings are supported by a molecular dynamics simulation of a 2D particle system.

Three-dimensional structure of Mach cones in monolayer complex plasma crystals.

The structure of Mach cones in a crystalline complex plasma has been studied experimentally using an intensity sensitive imaging, which resolved particle motion in three dimensions. This revealed a previously unknown out-of-plane cone structure, which appeared due to excitation of the vertical wave mode. The complex plasma consisted of micron sized particles forming a monolayer in a plasma sheath of a gas discharge. Fast particles, spontaneously moving under the monolayer, created Mach cones with multiple structures. The in-plane cone structure was due to compressional and shear lattice waves.

[Characteristics of tumor growth in patients with locally-advanced gastric cancer].

Locally-advanced gastric cancer features predominance of prognostically unfavorable histological patterns (infiltrative growth--in 87.9%, tumor grades II-IV--69.5%). Tumor invasion into two adjacent organs or more frequently occurs in totally-involved stomach (65.2+/-9.7%), poorly-differentiated (grade Ill) tumors (44.9+/-4.5%) under-differentiated ones (grade IV) (45.9+/-8.2%). Invasion into one adjacent organ is significantly predominant (p

Plastic deformations in complex plasmas.

Complex plasmas are macroscopic model systems of real solids and liquids, used to study underdamped dynamics and wave phenomena. Plastic deformations of complex plasma crystals under slow uniaxial compression have been studied experimentally and numerically. It is shown that the lattice becomes locally sheared and that this strain is relaxed by shear slips resulting in global uniform compression and heat generation. Shear slips generate pairs of dislocations which move in opposite directions at subsonic speeds.

Soliton interaction in a complex plasma.

The interaction of two counterpropagating solitons of equal amplitudes has been studied experimentally and numerically in a monolayer strongly coupled complex plasma. Complex plasmas are microparticle suspensions in ion-electron plasmas. It was found that the solitons are delayed after the collision. Solitons with higher amplitude experience longer delays. The amplitude of the overlapping solitons during the collision was less than the sum of the initial soliton amplitudes.

[Outcomes of surgical treatment for locally advanced gastric cancer].

Results of surgical treatment of 223 patients with locally advanced gastric cancer (2000-2005) are presented. Postoperative complications rate was 25.6 +/- 2.5%, mortality--5.8 +/- 0.7%, overall survival--17.9 +/- 2.6%, median survival--12 months. Survival rates were higher following palliative treatment. Groups of patients in which RO resections failed to improve the end results were identified. That in turn calls for working out differentiated surgical strategies.

High speed laser tomography system.

A high speed laser tomography system was developed capable of acquiring three-dimensional (3D) images of optically thin clouds of moving micron-sized particles. It operates by parallel-shifting an illuminating laser sheet with a pair of galvanometer-driven mirrors and synchronously recording two-dimensional (2D) images of thin slices of the imaged volume. The maximum scanning speed achieved was 120,000 slices/s, sequences of 24 volume scans (up to 256 slices each) have been obtained. The 2D slices were stacked to form 3D images of the volume, then the positions of the particles were identified and followed in the consecutive scans. The system was used to image a complex plasma with particles moving at speeds up to cm/s.

Kinetic characterization of strongly coupled systems.

We propose a simple method to determine the local coupling strength Gamma experimentally, by linking the individual particle dynamics with the local density and crystal structure of a 2D plasma crystal. By measuring particle trajectories with high spatial and temporal resolution we obtain the first maps of Gamma and temperature at individual particle resolution. We employ numerical simulations to test this new method, and discuss the implications to characterize strongly coupled systems.

Recrystallization of a 2D plasma crystal.

A monolayer plasma crystal consisting of micron-sized particles levitated in the sheath of a rf discharge was melted by applying a short electric pulse to two parallel wires located at the height of the particles. Structural properties and the particle temperature were examined during the stage of recrystallization. A liquidlike phase was followed by a transient state characterized by energy release and the restoring of long range translational order while the defect fraction was low. No long range orientational order was found, though highly ordered domains formed locally. Numerical simulations revealed the same regimes of recrystallization as those observed in the experiment.

Self-diffusion in a liquid complex plasma.

Self-diffusion has been experimentally studied in a two-dimensional underdamped liquid complex (dusty) plasma. It was found that the self-diffusion coefficient D increases linearly with the temperature T: D/omega(E)a2 = (0.019 +/- 0.007)(T/T(m) - 1), where T(m), omega(E), and a are the melting temperature, the Einstein frequency, and the mean particle separation, respectively. No superdiffusion was observed, whereas a subdiffusion occurred at temperatures close to melting.

Heat transfer in a two-dimensional crystalline complex (dusty) plasma.

Heating and heat transfer were studied in a two-dimensional crystalline complex plasma at the kinetic level. The lattice was formed of microspheres levitated in a plasma sheath. One half of the crystal was heated anisotropically to obtain higher kinetic temperatures in one direction and heat conduction was observed in real time. It was found that the longitudinal phonons conduct heat better than the transverse. The thermometric conductivity coefficient was measured to be 53 mm2/s for longitudinal heating and 30 mm2/s for transverse heating. Heat decay lengths and energy exchange times between the temperature components were determined.

Vertical wave packets observed in a crystallized hexagonal monolayer complex plasma.

Propagation of vertical wave packets was observed experimentally in a crystallized hexagonal monolayer complex plasma. It was found that the phase velocity exceeded the group velocity by a factor 65 and was directed into the opposite direction as expected for an inverse optical-like dispersion relation. The wave packets propagated keeping their width constant. The explanation of this behavior is based on three-dimensional equations of motion and uses a long-wavelength weak dispersion weak inhomogeneity approximation. While the wave dispersion causes the wave packet to spread, lattice inhomogeneity and neutral gas drag counteract spreading. A plasma diagnostic method was developed that is based on the ratio between vertical and dust-lattice wave speeds. This ratio is very sensitive to the lattice parameter kappa (ratio of the particle separation to the screening length) in a very useful range of kappa < or = 2 . It was found that only a two-dimensional lattice model can provide a quantitative description of the vertical waves, while a linear chain model gives only a qualitative agreement.

Wave spectra in solid and liquid complex (dusty) plasmas.

Spectra of longitudinal and transverse waves were obtained experimentally in liquid and solid two-dimensional complex (dusty) plasmas at different kinetic temperatures. As the temperature increased and the phase state of the plasma changed from solid to liquid, the phonon spectra of both longitudinal and transverse modes broadened (especially at high wave numbers), indicating increased damping. The transverse mode disappeared and a thermal (compressional) mode appeared.

Shock melting of a two-dimensional complex (dusty) plasma.

Shock waves with a linear front were experimentally studied in a monolayer hexagonal Yukawa lattice which was formed from charged monodisperse plastic microspheres and levitated in the sheath of a radio-frequency discharge. It was found that the shock can cause phase transitions from a crystalline to gaslike and liquidlike states. Melting occurred in two stages. First, the lattice was compressed in the direction of shock propagation and second, the particle velocities were randomized a few lattice lines downstream. The Mach number of the shock reached 2.7.