Under- and over-water halves of Gyrinidae beetle eyes harbor different corneal nanocoatings providing adaptation to the water and air environments.

Whirligig beetles (Gyrinidae) inhabit water surfaces and possess unique eyes which are split into the overwater and underwater parts. In this study we analyze the micro- and nanostructure of the split eyes of two Gyrinidae beetles genera, Gyrinus and Orectochilus. We find that corneae of the overwater ommatidia are covered with maze-like nanostructures, while the corneal surface of the underwater eyes is smooth. We further show that the overwater nanostructures possess no anti-wetting, but the anti-reflective properties with the spectral preference in the range of 450-600 nm. These findings illustrate the adaptation of the corneal nanocoating of the two halves of an insect's eye to two different environments. The novel natural anti-reflective nanocoating we describe may find future technological applications

Comparison of electron transport in polar materials for the models of low-density and high-density electron gas. Application to bulk GaN

We analyzed the steady-state electron transport for bulk GaN in frame of two opposite approaches: the electron temperature approach that assumes a high-density electron gas and numerical single-particle Monte-Carlo method that assumes a lowdensity electron gas and does not take into account electron-electron (e-e) scattering. We have also presented an analytical solution of the Boltzmann transport equation based on diffusion approximation. The transport characteristics such as the drift velocity electric field, V d (E), and mean electron energy electric field, ε(E), have been calculated at nitrogen and room temperatures in the wide range of applied electric fields from zero fields up to runaway ones (~100 kV/cm) for both approaches. Our calculations were performed for doped semiconductor with equal impurity and electron concentrations, Ni = n =10¹⁶ cm⁻³. The electron distribution functions in various ranges of applied fields have been also demonstrated. Within the range of heating applied fields 0– 300 V/cm, we found a strong difference between the transport characteristics obtained by means of the balance equations (electron temperature approach) and Monte-Carlo procedure. However, the Monte-Carlo calculations and diffusion approximation show a good agreement at 77 K. Within the range of moderate fields 1–10 kV/cm at 77 K, we established that the streaming effect can occur for low-density electron gas. In spite of significant dissimilarity of a streaming-like and a shifted Maxwellian distribution functions, the calculated values of Vd(E) and ε(E) show similar sub-linear behavior as the functions of the applied field E. In the high-field range 20–80 kV/cm, the streaming effect is broken down, and we observe practically linear behavior of both Vd(E) and ε(E) for both approaches. At higher fields, we point out the initiation of the runaway effect

Optimal Fractionation of Products of Refining Straight-run Gasoline on Zeolite Catalyst with Account of its Deactivation

Flowsheet of industrial refining straight-run gasoline on zeolite catalyst includes the necessary stage of fractionation of conversion products to produce commercial gasoline, gas and heavy residue. Changes in qualitative and quantitative compositions of the catalytic conversion products under catalyst deactivation require current parametrical optimization of this stage. Objective functions that take into account catalyst deactivation and the constrains depending on the requirements for product quality and equipment specifications were developed. Optimal conditions were found to differ significantly from those designed for fresh catalyst

ВЫБОР СЕТЧАТОГО ИМПЛАНТАНТА ДЛЯ ПЛАСТИКИ LICHTENSTEIN У МУЖЧИН РЕПРОДУКТИВНОГО ВОЗРАСТА

The article deals with the impact of polypropylene and polyester mesh implants on the sexual function of men of reproductive age after the plastic surgery of the inguinal canal in the Lichtenstein technique. For an adequate comparison of groups of patients with established polypropylene and polyester implants, an algorithm for their examination was developed. For a comprehensive assessment of sexual function in the study, it is divided into two components. Fertility of 155 patients was assessed through the analysis of spermiological studies performed in young patients with inguinal hernia. The possible reason of the immunological form of sterility, against the background of established reticular endoprostheses, a spermiological study in each patient was supplemented with a Mar-test in order to search for antisperm antibodies. To assess the copulative component of sexual function, patients of both groups were questioned according to the questionnaire “International Index of Erectile Function, Version 5” (ICEF 5). After statistical processing of the data based on the developed algorithm, no statistically significant differences between the groups of patients with established polypropylene and polyester implants were revealed. However, in one patient in the group where polypropylene mesh endoprostheses were used, changes in the spermiological analysis taken after the operative allowance, which can speak of a sharp decrease in the quality of the ejaculate, up to the development of sterility, are revealed. Also, this patient recorded a decrease below the ICEF 5. The results of the study, conclusions were drawn and recommendations were given to practicing surgeons about the possibility of using polypropylene and polyester reticular endoprostheses in plastics of the posterior wall of the inguinal canal in men of reproductive age.В статье разбираются вопросы влияния полипропиленовых и полиэстеровых сетчатых имплантов на половую функцию мужчин репродуктивного возраста после перенесенной пластики пахового канала в методике Lichtenstein. Для адекватного сравнения групп пациентов с установленными полипропиленовыми и полиэстеровыми имплантантами разработан алгоритм их обследования. Для комплексной оценки половой функции в исследовании она подразделена на две компоненты. Фертильность 155 больных оценена через анализ спермиологических исследований, выполненных у молодых больных с паховыми грыжами. В связи с возможным развитием иммунологической формы стерильности на фоне установленных сетчатых эндопротезов спермиологическое исследование у каждого больного было дополнено Mar-тестом с целью поиска антиспермальных антител. Для оценки копулятивной компоненты половой функции больные обеих групп были анкетированы согласно опроснику «Международный индекс эректильной функции, версия 5» (МИЭФ 5). После статистической обработки данных, собранных на основании разработанного алгоритма, статистически значимых различий между группами больных с установленными полипропиленовыми и полиэстеровыми имплантантами выявлено не было. Однако у одного больного в группе, где использовались полипропиленовые сетчатые эндопротезы, выявлены изменения в спермиологическом анализе, взятого после оперативного пособия, которые могут говорить о резком снижении качества эякулята, вплоть до развития стерильности. Также у этого пациента зафиксировано снижение ниже нормы балла МИЭФ 5. На основании результатов исследования сделаны выводы и даны рекомендации для практикующих хирургов о возможности применения полипропиленовых и полиэстеровых сетчатых эндопротезов при пластики задней стенки пахового канала у мужчин репродуктивного возраста

The experimental research of the electric characteristics of discharge in the quasi-steady plasma accelerator with the longitudinal magnetic field

Installation of the coaxial quasi-steady high-current one-stage plasma accelerator with a longitudinal magnetic field is created. The lead experiments have shown an opportunity of realization of the discharges, formation of the ionization front and generation of the plasma streams at the presence of a longitudinal field in the accelerator channel. The currentvoltage characteristics of the discharge at the presence and absence of a longitudinal field are measured. It is established that a weak longitudinal field does not render the appreciable influence on the integrated characteristics of discharge in the accelerator with the rod anode in an ion current transport regime.Створено установку коаксіального квазістаціонарного сильнострумового одноступеневого плазмового прискорювача з подовжнім магнітним полем. Проведено експерименти, які продемонстрували можливість здійснення розрядів, формування фронту іонізації й генерації потоків плазми за умови існування подовжнього магнітного поля в каналі прискорювача. Виміряні вольтамперні характеристики розряду при наявності та відсутності подовжнього поля. Встановлено, що слабке подовжнє поле не створює значного впливу на інтегральні характеристики розряду в прискорювачі зі стрижневим анодом в режимі іонного струмопереносу.Создана установка коаксиального квазистационарного сильноточного одноступенчатого плазменного ускорителя с продольным магнитным полем. Проведенные эксперименты продемонстрировали возможность осуществления разрядов, формирования фронта ионизации и генерации потоков плазмы при наличии продольного поля в канале ускорителя. Измерены вольтамперные характеристики разряда при наличии и отсутствии продольного поля. Установлено, что слабое продольное поле не оказывает заметного влияния на интегральные характеристики разряда в ускорителе со стрежневым анодом в режиме ионного токопереноса

Spontaneous decay in the presence of dispersing and absorbing bodies: general theory and application to a spherical cavity

A formalism for studying spontaneous decay of an excited two-level atom in the presence of dispersing and absorbing dielectric bodies is developed. An integral equation, which is suitable for numerical solution, is derived for the atomic upper-state-probability amplitude. The emission pattern and the power spectrum of the emitted light are expressed in terms of the Green tensor of the dielectric-matter formation including absorption and dispersion. The theory is applied to the spontaneous decay of an excited atom at the center of a three-layered spherical cavity, with the cavity wall being modeled by a band-gap dielectric of Lorentz type. Both weak coupling and strong coupling are studied, the latter with special emphasis on the cases where the atomic transition is (i) in the normal-dispersion zone near the medium resonance and (ii) in the anomalous-dispersion zone associated with the band gap. In a single-resonance approximation, conditions of the appearance of Rabi oscillations and closed solutions to the evolution of the atomic state population are derived, which are in good agreement with the exact numerical results.Comment: 12 pages, 6 figures, typos fixed, 1 figure adde

Polynomial Lie algebra methods in solving the second-harmonic generation model: some exact and approximate calculations

We compare exact and SU(2)-cluster approximate calculation schemes to determine dynamics of the second-harmonic generation model using its reformulation in terms of a polynomial Lie algebra $su_{pd}(2)$ and related spectral representations of the model evolution operator realized in algorithmic forms. It enabled us to implement computer experiments exhibiting a satisfactory accuracy of the cluster approximations in a large range of characteristic model parameters.Comment: LaTex file, 13 pages, 3 figure

Status of the Lake Baikal Experiment

We review the present status of the Baikal Underwater Neutrino Experiment and report on neutrino events recorded with the detector stages NT-36 and NT-96.Comment: 5 pages, 4 PostScript figures, uses here.sty and mine.sty, submitted to the Proc. of 5th Int. Workshop on Topics in Astroparticle and Underground Physics (LNGS INFN, Assergi, September 7-11, 1997

Metric Properties of the Fuzzy Sphere

The fuzzy sphere, as a quantum metric space, carries a sequence of metrics which we describe in detail. We show that the Bloch coherent states, with these spectral distances, form a sequence of metric spaces that converge to the round sphere in the high-spin limit.Comment: Slightly shortened version, no major changes, two new references, version to appear on Letters in Mathematical Physic

Registration of atmospheric neutrinos with the Baikal neutrino telescope

We present first neutrino induced events observed with a deep underwater neutrino telescope. Data from 70 days effective life time of the BAIKAL prototype telescope NT-96 have been analyzed with two different methods. With the standard track reconstruction method, 9 clear upward muon candidates have been identified, in good agreement with 8.7 events expected from Monte Carlo calculations for atmospheric neutrinos. The second analysis is tailored to muons coming from close to the opposite zenith. It yields 4 events, compared to 3.5 from Monte Carlo expectations. From this we derive a 90 % upper flux limit of 1.1 * 10^-13 cm^-2 sec^-1 for muons in excess of those expected from atmospheric neutrinos with zenith angle > 150 degrees and energy > 10GeV.Comment: 20 pages, 11 figure