Identification and assessment of geohazards affecting pipelines and urban areas

The paper addresses methods and criteria of risk assessment associated with land subsidence threatening pipelines, buildings, and constructions. Currently, there are some practical issues relating to geohazards that should be taken into account while constructing a pipeline. The article provides comparison data on the effects of Spitak earthquake and the natural disaster in Neftegorsk in terms of geohazards impact on the pipeline systems. The suggested risk assessment procedure embraces a wide range of aspects: from soil properties to economic and management issues

Механизмы реагирования ритмической структуры внешнего дыхания у больных бронхиальной астмой на прерывистую нормобарическую гипокситерапию

The method of intermittent normobaric hypoxic therapy (INHT) was applied in 82 asthmatic patients to investigate the response of respiratory circadian rhythms to hypoxic stimulation. Results of the study showed that the INHT effect was appeared as a growth of average daily values of the lung vital capacity and forced expiration volume provided mainly by unidirectional changes in medium and small bronchi resistance. The achrophase synchronisation of the intrasystemic parameters and vanishing of the daily and the 12-h rhythms took place along with restoration of the blood oxygenation rhythm.The lung volume and flow rate parameters of the morning chronotype responded to the hypoxic training by considerable changes in the phase values under insignificant dynamics of the quantitative rhythm parameters, such as amplitude and measure. On the contrary, the rhythm variations of the evening chronotype were characterised by great changes in the amplitude and the measure while the achrophase shift was unreliable.Методом прерывистой нормобарической гипокситерапии (ПНГ) пролечены 32 больных с бронхиальной астмой с целью изучения динамики циркадианных ритмов внешнего дыхания на гипоксическую стимуляцию. Результаты исследования показали, что эффект ПНГ выражается в приросте среднесуточных показателей жизненной емкости легких (Ж ЕЛ) и объема форсированного выдоха в основном за счет однонаправленных изменений сопротивления бронхов среднего и мелкого калибра. Происходит синхронизация акрофаз внутрисистемных показателей, исчезновение внутрисуточной и собственно 12-часовой ритмики с восстановлением ритма оксигенации крови.Объемные и скоростные параметры дыхания у пациентов, относящихся к утреннему хронотипу, реагируют на гипоксическую тренировку достоверным изменением фазовых величин при незначительных изменениях количественных показателей ритма — амплитуды и мезора. Динамика ритмических колебаний в вечерней подгруппе, наоборот, характеризуется значимым изменением амплитудно-мезорных величин, в то время как смещение акрофаз недостоверн

Soft X-ray harmonic comb from relativistic electron spikes

We demonstrate a new high-order harmonic generation mechanism reaching the `water window' spectral region in experiments with multi-terawatt femtosecond lasers irradiating gas jets. A few hundred harmonic orders are resolved, giving uJ/sr pulses. Harmonics are collectively emitted by an oscillating electron spike formed at the joint of the boundaries of a cavity and bow wave created by a relativistically self-focusing laser in underdense plasma. The spike sharpness and stability are explained by catastrophe theory. The mechanism is corroborated by particle-in-cell simulations

X-ray harmonic comb from relativistic electron spikes

X-ray devices are far superior to optical ones for providing nanometre spatial and attosecond temporal resolutions. Such resolution is indispensable in biology, medicine, physics, material sciences, and their applications. A bright ultrafast coherent X-ray source is highly desirable, for example, for the diffractive imaging of individual large molecules, viruses, or cells. Here we demonstrate experimentally a new compact X-ray source involving high-order harmonics produced by a relativistic-irradiance femtosecond laser in a gas target. In our first implementation using a 9 Terawatt laser, coherent soft X-rays are emitted with a comb-like spectrum reaching the 'water window' range. The generation mechanism is robust being based on phenomena inherent in relativistic laser plasmas: self-focusing, nonlinear wave generation accompanied by electron density singularities, and collective radiation by a compact electric charge. The formation of singularities (electron density spikes) is described by the elegant mathematical catastrophe theory, which explains sudden changes in various complex systems, from physics to social sciences. The new X-ray source has advantageous scalings, as the maximum harmonic order is proportional to the cube of the laser amplitude enhanced by relativistic self-focusing in plasma. This allows straightforward extension of the coherent X-ray generation to the keV and tens of keV spectral regions. The implemented X-ray source is remarkably easily accessible: the requirements for the laser can be met in a university-scale laboratory, the gas jet is a replenishable debris-free target, and the harmonics emanate directly from the gas jet without additional devices. Our results open the way to a compact coherent ultrashort brilliant X-ray source with single shot and high-repetition rate capabilities, suitable for numerous applications and diagnostics in many research fields

LATE VENTRICULAR POTENTIALS AND CARDIAC ARRHYTHMIAS IN PATIENTS WITH CARDIAC CONNECTIVE TISSUE DYSPLASIA AND ARTERIAL HYPERTENSION

To investigate the association between late ventricular potentials and cardiac arrhythmias, 35 patients with cardiac connective tissue dysplasia (CTD), 34 patients with cardiac CTD and arterial hypertension (AH), and 39 relatively healthy people were examined. All participants underwent 24-hour ECG monitoring, echocardiography, and high definition ECG, in accordance with the 1999 clinical guidelines by the European Society of Cardiology. The duration of filtered QRS signal and low-amplitude signals at 40 mkV level in the end of QRS, as well as mean quadratic amplitude of the last 40 ms of filtered QRS signal, were assessed. High definition ECG and Holter ECG monitoring facilitates the prediction of life-threatening ventricular arrhythmias in patients with cardiac CTD

Aperiodic components in optics of soft x-ray region

This book is devoted to the design, implementation and application of two kinds of aperiodic optical components of vacuum ultraviolet and soft x-ray spectral regions - aperiodic multilayer mirrors and reflective diffraction gratings with the groove density monotonically varying along the aperture in accordance with a prescribed dependence (Varied Line-Space gratings). New capabilities opened by these components are described

Aperiodic reflection diffraction gratings for soft X-ray radiation and their application

We briefly review the works concerned with the development and experimental use of the spectral instruments based on aperiodic reflection gratings whose spacing varies monotonically across the aperture according to a prescribed law (VLS gratings). The review considers the employment of VLS-grating instruments intended for the spectroscopy of laboratory and astrophysical plasmas, including the diagnostics of relativistic laser plasmas, for measuring X-ray laser linewidths, for recording the high-order harmonics of laser radiation, the radiation of fast electric discharges and other laboratory X-ray sources, as well as in reflectometry, X-ray fluorescence analysis and microscopy with the use of synchrotron radiation and laser-plasma radiation, and in emission spectroscopy combined with an electron microscope. Also discussed are achievements in the recently undertaken design and development of special-purpose VLS spectrometers intended for the investigation of the electronic structure of different materials and molecules by the spectroscopic technique of resonant inelastic X-ray scattering of synchrotron radiation. We describe flat-field grazing-incidence spectrometers with concave VLS gratings, which are compatible with modern CCD detectors, as well as plane VLS gratings, which are the key elements of scanning high- and ultrahigh-resolution spectrometers/monochromators with a constant deviation angle and stigmatic (imaging) spectrometers, which are also compatible with CCD detectors

Soft X-ray spectrometers based on aperiodic reflection gratings and their application

This paper is concerned with the history, properties, development, application and prospects of soft X-ray (2 – 300 Å) VLS spectrometers, i.e. spectrometers with reflection diffraction gratings whose spacing varies monotonically across the aperture according to a prescribed law (the so-called Varied Line-Space (VLS) gratings). An important feature of grazing-incidence VLS spectrometers is that the spectrum is formed on a nearly flat surface perpendicular (or slightly inclined) to the diffracted beams, making them perfectly compatible with modern CCD detectors (backside-illuminated CCDs). VLS spectrometers are employed for the spectroscopy of laboratory and astrophysical plasmas, including the diagnostics of relativistic laser-produced plasmas, for measuring the linewidth of an X-ray laser, recording the high-order harmonics of laser radiation, the emission of fast electric discharges and other laboratory X-ray sources. Instruments with VLS gratings are employed to advantage in reflectometry/metrology, X-ray fluorescence analysis, and microscopy with the use of synchrotron, free-electron laser, and laser-produced plasma radiation, as well as in SXR emission spectroscopy combined with an electron microscope (SXES). Recent years have seen the active development of VLS spectrometers dedicated to the investigation of the electronic structure of different materials and molecules by resonant inelastic X-ray scattering (RIXS) spectroscopy with synchrotron radiation. Among recent trends is the development of VLS gratings with a multilayer reflective coating and extension of the operating spectral range towards "tender" X-rays (ℏω∼ 1.5...6 keV), some projects aiming to achieve a resolving power λ/δλ∼105 in the region ℏω∼ 1 keV. Keywords: soft X-ray radiation, aperiodic reflection diffraction grating (VLS grating), flat-field spectrometer, scanning spectrometer/monochromator, stigmatic (imaging) spectrometer

High Spectral and Spatial Resolution Soft X-ray/XUV VLS Spectrographs

We report the implementation of three high-resolution VLS-grating spectrometers intended for laboratory applications: (i) an inherently stigmatic (imaging) broadband (12.5–30 nm) spectrograph, which uses the synergy of an aperiodic normal-incidence multilayer mirror and a plane grazing-incidence VLS grating; (ii) a scanning spectrometer/monochromator of the Hettrick–Underwood type with a constant deviation angle and a nearly constant focal distance at wavelengths λ < 30 nm; (iii) a flat-field 0.5-m long spectrograph of the Harada type. Broadband (11–14 nm) aperiodic Mo/Be multilayers were designed for extending the range of the imaging spectrograph to 11 nm. Numerical techniques were developed to calculate interference lithography configurations that provide the desired line density variation across the aperture of plane/concave VLS gratings