Analytic description of high-order harmonic generation in the adiabatic limit with application to an initial \u3ci\u3es\u3c/i\u3e state in an intense bicircular laser pulse

An analytic description of high-order harmonic generation (HHG) is proposed in the adiabatic (low-frequency) limit for an initial s state and a laser field having an arbitrary wave form. The approach is based on the two-state time-dependent effective range theory and is extended to the case of neutral atoms and positively charged ions by introducing ad hoc the Coulomb corrections for HHG. The resulting closed analytical form for the HHG amplitude is discussed in terms of real classical trajectories. The accuracy of the results of our analytic model is demonstrated by comparison with numerical solutions of the time-dependent Schrödinger equation for a strong bicircular field composed of two equally intense components with carrier frequencies ω and 2ω and opposite helicities. In particular, we demonstrate the effect of ionization gating on HHG in a bicircular field, both for the case that the two field components are quasimonochromatic and for the case that the field components are time-delayed short pulses. We show how ionization in a strong laser field not only smooths the usual peak structures in HHG spectra but also changes the positions and polarization properties of the generated harmonics, seemingly violating the standard dipole selection rules. These effects appear for both short and long incident laser pulses. In the case of time-delayed short laser pulses, ionization gating provides an effective tool for control of both the HHG yield and the harmonic polarizations [Frolov et al., Phys. Rev. Lett. 120, 263203 (2018)]. For the case of short laser pulses, we introduce a simple two-dipole model that captures the physics underlying the harmonic emission process, describing both the oscillation patterns in HHG spectra and also the dependence of the harmonic polarizations on the harmonic energy

Control of Harmonic Generation by the Time Delay Between Two-Color, Bicircular Few-Cycle Mid-IR Laser Pulses

We study control of high-order harmonic generation (HHG) driven by time-delayed, few-cycle ω and 2ω counterrotating mid-IR pulses. Our numerical and analytical study shows that the time delay between the two-color pulses allows control of the harmonic positions, both those allowed by angular momentum conservation and those seemingly forbidden by it. Moreover, the helicity of any particular harmonic is tunable from left to right circular without changing the driving pulse helicity. The highest HHG yield occurs for a time delay comparable to the fundamental period T = 2π/ω

Spectrum of bound fermion states on vortices in 3^3He-B

We study subgap spectra of fermions localized within vortex cores in $^3$He-B. We develop an analytical treatment of the low-energy states and consider the characteristic properties of fermion spectra for different types of vortices. Due to the removed spin degeneracy the spectra of all singly quantized vortices consist of two different anomalous branches crossing the Fermi level. For singular $o$ and $u$ vortices the anomalous branches are similar to the standard Caroli-de Gennes -Matricon ones and intersect the Fermi level at zero angular momentum yet with different slopes corresponding to different spin states. On the contrary the spectral branches of nonsingular vortices intersect the Fermi level at finite angular momenta which leads to the appearance of a large number of zero modes, i.e. energy states at the Fermi level. Considering the $v$, $w$ and $uvw$ vortices with superfluid cores we show that the number of zero modes is proportional to the size of the vortex core.Comment: 6 pages, 1 figur

Пенолиты – новый тип эндогенных горных пород (о. Бельковский, Россия)

The results of a comprehensive study of a slag-like sideritolite, a representative of a previously unknown genetic type of rock, are summarized. The nano- microstructural features, chemical composition, trace elements, the constitution and the spectroscopic properties of the pore-forming and accessory minerals were investigated. Using the mineralogical and ontogenetic method, the history of rock formation was defined. Penoliths, the slag-like sideritolite, may be identified as a new genetic type of endogenous rocks formed directly in the bubbly foam.Обобщены результаты комплексного изучения шлакоподобного сидеритолита – представителя ранее неизвестного генетического типа горных пород. Исследованы наномикроструктурные особенности, химический состав, микроэлементы, конституция и спектроскопические свойства породообразующих и акцессорных минералов. С использованием минералого-онтогенического метода расшифрована история образования породы, сделан вывод о том, что шлакоподобный сидеритолит может быть определен как представитель нового генетического типа эндогенных горных пород – пенолитов, образующихся непосредственно в пузыристой пене

Tunka Advanced Instrument for cosmic rays and Gamma Astronomy

The paper is a script of a lecture given at the ISAPP-Baikal summer school in 2018. The lecture gives an overview of the Tunka Advanced Instrument for cosmic rays and Gamma Astronomy (TAIGA) facility including historical introduction, description of existing and future setups, and outreach and open data activities.Comment: Lectures given at the ISAPP-Baikal Summer School 2018: Exploring the Universe through multiple messengers, 12-21 July 2018, Bol'shie Koty, Russi

Flat bands in topological media

Topological media are systems whose properties are protected by topology and thus are robust to deformations of the system. In topological insulators and superconductors the bulk-surface and bulk-vortex correspondence gives rise to the gapless Weyl, Dirac or Majorana fermions on the surface of the system and inside vortex cores. Here we show that in gapless topological media, the bulk-surface and bulk-vortex correspondence is more effective: it produces topologically protected gapless fermions without dispersion -- the flat band. Fermion zero modes forming the flat band are localized on the surface of topological media with protected nodal lines and in the vortex core in systems with topologically protected Fermi points (Weyl points). Flat band has an extremely singular density of states, and we show that this property may give rise in particular to surface superconductivity which could exist even at room temperature.Comment: 9 pages, 5 figures, version to appear in JETP Letter

Оценка протективных эффектов будесонида у больных с кардиореспираторной коморбидностью при коронарном шунтировании с искусственным кровообращением

The objective: evaluation of the effect of budesonide and low-volume mechanical ventilation (LVMV) on pulmonary volemia, oxygen transport and respiratory biomechanics in patients with concurrent ischemic heart disease (IHD) and chronic obstructive pulmonary disease (COPD) during coronary artery bypass grafting (CABG) with artificial circulation (AC).Subjects and Methods. 50 patients with concurrent IHD and COPD were enrolled in the study. During AC, patients of Group I (20 people) received mechanical ventilation with the peak inspiratory pressure of 15 mbar, tidal volume of 3‒4 ml/kg, positive end-expiratory pressure of 5 mbar in combination with inhalation of nebulized budesonide. In Group II (30 people), the similar isolated respiratory support was provided. Pulmonary blood volume, indices of extravascular lung water (EVLW), pulmonary vascular permeability (PVPI), oxygen delivery (DO2I) and consumption (VO2I), oxygen extraction ratio (O2ER), pulmonary shunt fraction (Qs/Qt), oxygenation index were determined. The study consisted of 3 stages: before AC, after its completion and one day after CABG.Results. Before CABG, the EVLW index in all patients exceeded the standard level by 67‒72%. After weaning from AC, it decreased by 23% in Group I and by 8% in Group II. In patients receiving budesonide, PVPI significantly decreased after artificial circulation, while in patients from Group II, it remained unchanged. DO2I and O2ER in all patients were within the reference range, and VO2I was below it with a minimum value in Group II after weaning from AC. In this cohort, the Qs/Qt level was significantly higher, while OI was lower versus patients from Group I. Among patients who received budesonide immediately after AC and 2 hours after it, pulmonary resistance decreased while lung compliance increased. In Group II, those parameters changed oppositely. In Group I, one case of hydrothorax was recorded, and in Group II, 2 patients were diagnosed with polysegmental pneumonia and 2 patients – with pneumothorax. The median duration of mechanical ventilation in the postoperative period made 220 minutes in Group I, and 290 minutes in Group II (p = 0.018).Conclusion. In patients with concurrent IHD and COPD, use of the combination of low-volume mechanical ventilation and inhalation of nebulized budesonide during AC stabilizes the volemic status of the lungs, improves the oxygenating function and respiratory biomechanics in the postperfusion and early postoperative periods of CABG.Цель: оценка влияния будесонида и малообъемной искусственной вентиляции легких (ИВЛ) на показатели легочной волемии, транспорта кислорода и биомеханики дыхания у больных с ишемической болезнью сердца (ИБС) с сопутствующей хронической обструктивной болезнью легких (ХОБЛ) при коронарном шунтировании (КШ) с искусственным кровообращением (ИК).Материалы и методы. В исследование включено 50 больных ИБС и ХОБЛ. Больным 1-й группы (20 человек) во время ИК продолжали ИВЛ с пиковым давлением на вдохе 15 мбар, дыхательным объемом 3–4 мл/кг, положительным давлением в конце выдоха 5 мбар в сочетании с ингаляцией небулизированного будесонида. Во 2-й группе (30 человек) проводили изолированную респираторную поддержку в аналогичном режиме. Определяли легочный объем крови, индексы внесосудистой воды легких (ИВСВЛ), проницаемости легочных сосудов (ИПЛС), доставки (DO2I) и потребления (VO2I) кислорода, коэффициент его утилизации (O2ER), фракцию легочного шунтирования крови (Qs/Qt), индекс оксигенации (ИО), биомеханические параметры легких. Исследование проводили на трех этапах: до начала ИК, после его завершения и через сутки после КШ.Результаты. До КШ показатель ИВСВЛ у всех больных превышал нормативный уровень на 67–72%. После отхода от ИК в 1-й группе он снижался на 23%, а во 2-й – на 8%. У больных, получавших будесонид, ИПЛС после ИК статистически значимо снижался, а у лиц 2-й группы он оставался неизменным. DO2I и O2ER у всех пациентов находились в референсном диапазоне, а VO2I был ниже его с минимальным значением во 2-й группе после отхода от ИК. В этой когорте уровень Qs/Qt был статистически значимо выше, а ИО – ниже, чем у больных 1-й группы. Среди лиц, получавших будесонид, сразу после ИК и через 2 ч после него сопротивление легочной ткани снижалось на фоне повышения ее комплаенса. Во 2-й группе имела место противоположная динамика этих показателей. В 1-й группе зафиксирован один случай гидроторакса, во 2-й – у 2 больных диагностирована полисегментарная пневмония и у 2 – пневмоторакс. Медиана продолжительности ИВЛ в послеоперационном периоде в 1-й группе составила 220 мин, во 2-й – 290 мин (p = 0,018).Вывод. У больных с ИБС и ХОБЛ применение комбинации малообъемной ИВЛ и ингаляции небулизированного будесонида в период ИК стабилизирует волемический статус легких, улучшает их оксигенирующую функцию и биомеханику дыхания в постперфузионном и раннем послеоперационном периодах КШ

First results of the tracking system calibration of the TAIGA-IACT telescope

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Georgia in 2015. An analytical survey

The paper is devoted to the analysis of internal and foreign political processes in Georgia in 2015. This analytical chronicle is to trace and describe the most important tendencies in such fields as the contention between political parties, the balance within the ruling coalition and the relations with Georgia’s key foreign partners. Though “Georgian Dream” (GD) government met the crisis and had to change premier by the end of the year, it managed to keep the leading position in domestic politics. The main opponent of the GD, the United National Movement (UNM) could not increase its influence. The Republican party of Georgia, the member of ruling coalition that has rather weak support from the voters, was able to strengthen its position in the government by getting some key offices. The expansion of cooperation with NATO does not bring near prospects of membership. Although every single measure the sides are taking seems to be insignificant, as a complex these measures can lead to a deeper involvement of NATO and USA in the South Caucasus. The relations with European Union are inertial and strongly overestimated in Georgian internal politics. The relations with Russia are routinized; both sides acknowledge the achievements of the normalization and do not expect any breakthrough