THz Smith-Purcell and grating transition radiation from metasurface: experiment and theory.

We report the results of experimental and theoretical studies of monochromatic coherent terahertz radiation generated by a short relativistic electron bunch interacting with a metasurface. The metasurface consists of subwavelength metal elements arranged on a dielectric substrate. The constructed theory explains the experimental spectra of Smith-Purcell radiation and grating transition radiation with very high precision. The orientational distribution of transition radiation shows a fine structure, which, as we suppose, may be due to contribution of coupling between the metasurface's elements.

[Practical potentials of using dexmedetomidine in oral and maxillofacial surgery]. / Prakticheskie vozmozhnosti primeneniia sovremennogo sedativnogo preparata pri anesteziologicheskom posobii v stomatologii i cheliustno-litsevoi khirurgii.

Dexmedetomidine is a selective α2 adrenoreceptor agonist. The drug has a set of useful properties due to wide prevalence of the receptors in a body. The article presents review of the literature of using dexmedetomidine in anesthetic practice of various surgery fields which positive results may be extrapolated to dentistry and maxillofacial surgery to solve important anesthesiologic problems. Inclusion of the drug in routine oral and maxillofacial surgery anesthesia can bring a significant amount of benefits: safe sedation for dental interventions, sedation for compromised airways without respiratory depression, improvement of intraoperative and postoperative analgesia, reduction of postoperative nausea, vomiting and postoperative shivering incidence, nephroprotection and stability of hypotensive hemodynamics, decrease of intraoperative blood loss. Thus, the dexmedetomidine may be a useful agent for anesthesia in oral and maxillofacial surgery that increases anesthesia safety and quality of medical care.

Smith-Purcell radiation from periodic beams.

Smith-Purcell effect is well known as a source of monochromatic electromagnetic radiation. In this paper we present the generalized theory of Smith-Purcell radiation from periodic beams. The form-factors describing both coherent and incoherent regimes of radiation are calculated. The radiation characteristics are investigated in two practically important frequency ranges, THz and X-ray, for two modulation profiles, most frequently used in practice - a train of microbunches and a Gaussian-shaped one, characterized by sinusoidal modulation with an arbitrary modulation depth. On the base of the theory developed we show that a modulated electron beam consisting of a set of bunches makes it possible to improve significantly the spectral line monochromaticity of the light emitted, reaching values better than 1% for short gratings. We demonstrate as well that Smith-Purcell radiation can be used for non-destructive diagnostics of the depth of modulation for partially modulated beams. These findings not only open up a new way to manipulate the light emission using Smith-Purcell effect but also promise a profound impact for other radiation sources based on charged particle beams, such as undulator radiation in FELs, next-generation X-ray radiation source based on inverse Compton scattering, in a wide range from THz to X-rays.

TRANSMERIDIAN JET LAG AND ITS PHARMACOLOGICAL CORRECTION.

The article deals with the development and correction of acute jet lag in a flight across several time zones. The investigation had the purpose to study dynamics of subjective and objective psychophysiological parameters and demonstrate methods of prophylaxis and correction of acute jet lag due to transmerdian flights. Subjects were 8 normal volunteers (experimental group) at the age of 26-55 years flying eastward over 7 times zones. The investigation included 3 stages: baseline, preparatory (21-d course of Euricoma longifolia extraction) and main (intake of donormil, cirkadin and artificial sleep during the flight). Functional diagnostics was performed on the baseline stage, on completion of the preparatory stage and on the next day after the flight (21-22 days from the beginning of the preparatory stage). Objective and subjective methods were used to evaluate the autonomic and cardiovascular systems and mental performance. In the control group (n = 4) functional diagnostics was performed on the same days. The investigations showed the benefit of preparation for transmeridian air travel and experimentally demonstrated positive effects of the proposed pharmacological correction of acute transmeridian jet lag.

[THE TREATMENT OF POSTOPERATIVE STRICTURE OF BILIARY DUCTS: A 15-YEARS EXPERIENCE AND OBSERVATIONS FROM THE PRACTICE].

Experience of performance of 160 operations for injuries and stricture of biliary ducts, was analyzed. In 36 patients before admittance to hospital there were performed interventions, which provide correction of injuries or their consequences. In majority (141) of patients hepaticojejunoanastomosis in accordance to Roux method or its reconstruction were performed. Other interventions (right-sided hemihepatectomy) were rarely performed. The procedure of anastomosis formation, permitting to connect the mucosae of joining organs in precision, was proposed. Clinical observations of correction of the biliary ducts stricture were presented.

Low-loss plasmon-triggered switching between reflected free-space diffraction orders.

Surface plasmon coupling of a TM polarized free space incident beam by means of the + 1st or the -2nd order of a smooth corrugation grating at a metal surface causes the cancellation of the diffracted -1st order free space beam and a maximum of the 0th order Fresnel reflection whereas the converse occurs midway between these two conditions. This implies that angular tilting of the element or wavelength scanning provokes the switching between the -1st and 0th reflected orders. This plasmon-mediated effect on propagating free-space beams exhibits remarkably low absorption losses.

[Peace-time gunshot maxillofacial injury in Arkhangelsk region].

We analyzed civilian gunshot wounds of maxillofacial area in 87 patients living in the Arkhangelsk region. It is noted that gunshot injuries most often occur as a result of the attempted suicide (45 cases (51,7%)), firearm associated crimes (33 cases (37,9%)) and careless handling with the weapon (9 cases (10,4%)). The most common wound canal features are described. In the majority of cases tangential gunshot wounds were seen (55 cases (63,2%)), penetrating wounds (19 cases (21,8%)) and perforating wounds (13 cases (15)). During the last years increased the number of gunshot injures by traumatic weapons (11 (12.6%)). It is recommended to take into consideration the direction and topography of the wound canals during the debridement.

[Surgical treatment of a solitary hepatic abscess].

Retrospective analysis of the treatment results of 120 patients, suffering solitary hepatic abscess (SHA), was conducted. The sanation methods, in accordance to technology, the treatment impact intensity and aggressiveness, may be divided on three lines: aspirational, draining and resectional. The method of sanation is selected on the background of morphological peculiarities of abscess--its sizes, by presence of sequesters, divisioning septs, dense rigid capsule, grade of periprocess. Surgical access is determined by the abscess localization, the patient's state severity, instrumental equipment of the clinic. Differentiated approach, taking into account genesis, sizes, localization and stage of its formation, constitutes a background of successful treatment of SHA. In totally formatted acute SHA, as a rule, the methods of choice are aspirational and aspiration-draining methods of sanation under ultrasonographic control or laparoscopy. In the presence of chronic SHA or suppurated parasitic hepatic cyst it is mandatory to select the resectional methods.

[The role of ischemical preconditioning in the development of ischemia-reperfusion hepatic injury in experiment].

The optimal regimen of preliminary ischemic preparation, in which the vessels occlusion causes minimal pathohistological hepatic changes without inhibition of its regeneration capacities, was studied in experiment. The ischemic-reperfusional damage of liver, using hepatoduodenal ligament crossclamping in various regimens, was modeled on 40 rabbits in a randomized experimental investigation. Morphological investigations of the animals liver fragments, taken immediately after ligament crossclamping and on the third postoperative day, were performed. There was established, that severity and reversibility of the hepatic tissue affection have differed, depending on the ischemia duration and reperfusion period. The vessels occlusion regimen with preliminary ischemic preparation was the most safe for hepatic tissue, without rude structural injuries and functional disorders, permitting to recommend it for clinical application as the optimal one while performance of hepatic resection in combination with afferent vascular exclusion.

Resonant-grating reflection extended to wide-band, large-aperture beams by waveguide-mode coalescence.

The resonant reflection of a free-space beam from a slab waveguide grating is rendered high bandwidth and angularly robust by using a bimodal high index waveguide. A deep double-sided corrugation gives rise to the coalescence of the resonant reflection peaks resulting in a top-hat reflection spectrum. A low-cost waveguide technology based on solar cell amorphous silicon is demonstrated in the near infrared in a polarizer application.

Spatially and polarization resolved plasmon mediated transmission through continuous metal films.

The experimental demonstration and characterization is made of the plasmon-mediated resonant transmission through an embedded undulated continuous thin metal film under normal incidence. 1D undulations are shown to enable a spatially resolved polarisation filtering whereas 2D undulations lead to spatially resolved, polarization independent transmission. Whereas the needed submicron microstructure lends itself in principle to CD-like low-cost mass replication by means of injection moulding and embossing, the present paper demonstrates the expected transmission effects on experimental models based on metal-coated photoresist gratings. The spectral and angular dependence in the neighbourhood of resonance are investigated and the question of the excess losses exhibited by surface plasmons is discussed.

Highly-dispersive dielectric transmission gratings with 100% diffraction efficiency.

A new approach for the realization of highly dispersive dielectric transmission gratings is presented, which enables the suppression of any reflection losses and, thus, 100% diffraction efficiency. By applying a simple two-mode-model a comprehensible explanation as well as a theoretical design of such a reflection-free transmission grating is presented.

Cancellation of the zeroth order in a phase mask by mode interplay in a high index contrast binary grating.

A new grating phase mask is designed that allows the cancellation of the zeroth transmitted order in a diffraction configuration where the grating period is smaller than twice the exposure wavelength. An analytical treatment based on the true-mode method delivers the structure parameters, achieving 100% interference contrast. This modal approach is used to describe the modal operation of the giant reflection to zero-order device.

[Application of mini-invasive technologies in the treatment of gastrointestinal bezoars].

The data on etiology, clinical signs, diagnosis and variety of approaches to the treatment of gastrointestinal bezoars were presented, basing on the worldwide literature analysis. The results of surgical treatment of patients for bezoars, using miniinvasive methods, are presented.

[Twenty-years experience of relaparotomy performance].

The results of 204 relaparotomy operations, performed by a single surgeon in 1985-2004 yrs, were analyzed. The data concerning primary operations, their order of emergency, complications, occurred in postoperative period, demanding relaparotomy performance, the causes of their occurrence, were presented.

99% efficiency measured in the -1st order of a resonant grating.

A resonant diffraction grating comprising a mirror, a dielectric layer and a high index corrugation at the layer-air interface is shown to exhibit off-Littrow the record diffraction efficiency of 99% in the -1st reflected order at 1064 nm wavelength thanks to the excitation of a leaky mode of the layer. Such high figure is obtained by a grating 5 to 10 times shallower than in current attempts to realize high efficiency all-dielectric gratings.

An intelligible explanation of highly-efficient diffraction in deep dielectric rectangular transmission gratings.

This paper describes in a very easy and intelligible way, how the diffraction efficiencies of binary dielectric transmission gratings depend on the geometrical groove parameters and how a high efficiency can be obtained. The phenomenological explanation is based on the modal method. The mechanism of excitation of modes by the incident wave, their propagation constants and how they couple into the diffraction orders helps to understand the diffraction process of such gratings and enables a grating design without complicated numerical calculations.

[Curative-tactical approaches in patients with pancreatic pseudocyst]. / Lechebno-takticheskie podkhody u bol'nykh s psevdokistoi podzheludochnoi zhelezy.

Experience of treatment in the clinic of 162 patients with pancreatic pseudocyst was analyzed. Modern principles of diagnosis and treatment of patients were adduced. Operation before the cyst capsule formation is compulsory, caused by the complications occurrence and the pancreonecrosis progression. External drainage of an acute pancreatic pseudocyst was performed in 61 patients, internal drainage--in 72. After external drainage the cyst recurrence was noted in 17, the pancreatic fistula formation--in 7 patients. The poorest results were noted in patients with infected pancreonecrosis and in pseudocyst formation.

Diffraction radiation from an ultrarelativistic charge in the plasma frequency limit.

Diffraction radiation (DR) from an ultrarelativistic particle in the high frequency limit is considered. The distribution of the emitted energy over angles and frequencies has been obtained. Both backward DR and forward DR have been explored. The maximum of backward DR is found to augment with increasing the oblique incidence angle.