First-principles envelope-function theory for lattice-matched semiconductor heterostructures

In this paper a multi-band envelope-function Hamiltonian for lattice-matched semiconductor heterostructures is derived from first-principles norm-conserving pseudopotentials. The theory is applicable to isovalent or heterovalent heterostructures with macroscopically neutral interfaces and no spontaneous bulk polarization. The key assumption -- proved in earlier numerical studies -- is that the heterostructure can be treated as a weak perturbation with respect to some periodic reference crystal, with the nonlinear response small in comparison to the linear response. Quadratic response theory is then used in conjunction with k.p perturbation theory to develop a multi-band effective-mass Hamiltonian (for slowly varying envelope functions) in which all interface band-mixing effects are determined by the linear response. To within terms of the same order as the position dependence of the effective mass, the quadratic response contributes only a bulk band offset term and an interface dipole term, both of which are diagonal in the effective-mass Hamiltonian. Long-range multipole Coulomb fields arise in quantum wires or dots, but have no qualitative effect in two-dimensional systems beyond a dipole contribution to the band offsets.Comment: 25 pages, no figures, RevTeX4; v3: final published versio

Synchronization of low-frequency oscillations in the human cardiovascular system

We investigate synchronization between the low-frequency oscillations of heart rate and blood pressure having in humans a basic frequency close to 0.1 Hz. A method is proposed for quantitative estimation of synchronization between these oscillating processes based on calculation of relative time of phase synchronization of oscillations. It is shown that healthy subjects exhibit on average substantially longer epochs of internal synchronization between the low-frequency oscillations in heart rate and blood pressure than patients after acute myocardial infarction. © 2009 American Institute of Physics. ͓DOI: 10.1063/1.3187794͔ The human cardiovascular system (CVS) is one of the most important physiological systems whose operation is governed by several rhythmic processes interacting with each other. The most significant among them are the main heart rhythm, respiration, and low-frequency (LF) oscillations in heart rate and blood pressure with a basic frequency close to 0.1 Hz having a great importance for maintaining cardiovascular homeostasis. The origin of these LF oscillations is still a subject of controversy. According to one hypothesis, the 0.1 Hz oscillations in heart rate and blood pressure are largely an index of baroreflex gain. On another hypothesis, these oscillations have a central origin and represent an intrinsic property of autonomous neural network. We have investigated interaction between the 0.1 Hz cardiovascular oscillations in healthy subjects and patients after acute myocardial infarction (AMI). Peculiarities of interaction of the elements of CVS reflect its state and may contain useful information for medical diagnostics. The interaction between the rhythms is studied using a phase synchronization measure based on the Hilbert transform. A method is proposed for quantitative estimation of synchronization by using an algorithm of automated detection of phase synchronization epochs. The method is based on a linear approximation of instantaneous phase difference of analyzed signals in a moving window. Recommendations on a choice of the method parameters ensuring its high efficiency are given. A statistical significance of the calculated synchronization measure is analyzed using surrogate data. It is shown that healthy subjects exhibit on average substantially longer epochs of synchronization between the LF oscillations in heart rate and blood pressure than patients after AMI. Arguments are adduced in favor of the concept that oscillations of heart rate and blood pressure with a frequency of about 0.1 Hz have a central origin. Moreover, these oscillations may be considered as different processes that exhibit a comparatively high internal synchronization between themselves in healthy subjects ensuring a high adaptability of the CVS

COMPARISON OF FOSINOPRIL AND ATENOLOL EFFECT ON HEART 0.1 HZ-RHYTHMS SYNCHRONIZATION AND BLOOD MICROCIRCULATION IN PATIENTS WITH ARTERIAL HYPERTENSION

Aim. To compare the effect of fosinopril and atenolol on synchronization of heart 0.1 Hz-rhythms and blood microcirculatory.Material and methods. 63 patients at the age of 47±8 with hypertension (HT) of grade 1-2 were enrolled in the study. 0.1 Hz-oscillations in heart rate variability (HRV) and in filling of microcirculatory bed were registered during passive tilt test under spontaneous breathing. The duration of each stage of test was 10 min. Synchronization was estimated as a phase difference between 0.1 Hz-rhythms of heart rate and filling of microcirculatory bed. Frequency values of HRV spectrum in LF- and HF-ranges were also assessed.Results. Fosinopril and atenolol showed comparable effect on blood pressure (BP) reduction. Atenolol decreased in heart rate significantly. Treatment with either fosinopril or atenolol in patients with significant vegetative dysfunction resulted in repair of functional interaction between heart 0.1 Hz-regulation and microcirculatory bed. Functional dissociation of 0.1 Hz-regulation mechanisms was observed under the treatment with fosinopril or atenolol in patients with initially sufficient interaction.Conclusions. Fosinopril and atenolol influenced similarly on heart 0.1 Hz-mechanisms and microcirculation autonomic regulation in patients with HT. Atenolol is a drug of choice in patients with sympathicotony. Both drugs should be administered in according with an individual level of 0.1-Hz rhythms synchronization assessed before start of the treatment

Microstructure and thermal stability of Fe, Ti and Ag implanted Yttria-stabilized zirconia

Yttria-stabilized zirconia (YSZ) was implanted with 15 keV Fe or Ti ions up to a dose of 8×1016 at cm−2. The resulting “dopant” concentrations exceeded the concentrations corresponding to the equilibrium solid solubility of Fe2O3 or TiO2 in YSZ. During oxidation in air at 400° C, the Fe and Ti concentration in the outermost surface layer increased even further until a surface layer was formed of mainly Fe2O3 and TiO2, as shown by XPS and ISS measurements. From the time dependence of the Fe and Ti depth profiles during anneal treatments, diffusion coefficients were calculated. From those values it was estimated that the maximum temperature at which the Fe- and Ti-implanted layers can be operated without changes in the dopant concentration profiles was 700 and 800° C, respectively. The high-dose implanted layer was completely amorphous even after annealing up to 1100° C, as shown by scanning transmission electron microscopy. Preliminary measurements on 50 keV Ag implanted YSZ indicate that in this case the amorphous layer recrystallizes into fine grained cubic YSZ at a temperature of about 1000° C. The average grain diameter was estimated at 20 nm, whereas the original grain size of YSZ before implantation was 400 nm. This result implies that the grain size in the surface of a ceramic material can be decreased by ion beam amorphisation and subsequent recrystallisation at elevated temperatures

Диагностическая эффективность ультрасонографии при метаэпифизарном остеомиелите у детей младшего возраста: проспективное исследование

INTRODUCTION: Modern and effective diagnosis of osteomyelitis is the basis for successful therapy; at the same time the problem of establishing this pathology, especially in the early stages of the development of the process, has not been completely resolved.OBJECTIVE: To develop of ultrasound imaging of metaepiphyseal osteomyelitis in young children, depending on the duration of the disease.MATERIAL AND METHODS: 108 children (boys — 65% (70/108), girls — 35 (38/108)) from 1 month to 2 years were examined. Children's age from 2 up to 8 months — 57% (62/108), newborns — 26% (27/108). The age of other children: 12% (13/108) — 9–12 months, 5% (6/108) — 1– 2 years. All children underwent x-ray and ultrasound study. The diagnosis of osteomyelitis was verified by joint puncture (n=102), bone puncture (n=57), drainage of periarticular phlegmon (n=12).Statistics: processing of the study results was carried out using the Statistica 13.0 application package (TIBCO Software Inc, 2017). To assess the effectiveness of ultrasound in the diagnosis of acute osteomyelitis, the diagnostic effectiveness and predictive value of positive or negative results were calculated, and the likelihood ratio was calculated.RESULTS: 3 groups were identified depending on the duration of the disease at the time of admission to the hospital: Ia — 1–3 days, Ib — 4–7 days, Group II — 8–14 days, Group III — 15–21 days from the onset of the disease. DE indicators for patients of group Ia: sensitivity — 81.8%, specificity — 60.0%, accuracy — 75%, PV(+)=81.82%; PV(–)=60.00%; OR=4.50. DE indicators for patients in group Ib: sensitivity — 86.6%, specificity — 66.6%, accuracy — 80.95%, PV(+)=87.5%; PV(–)=60.0%; OR=7.00. DE indicators for patients in group II: sensitivity — 92.98%, specificity — 80.0%, accuracy — 93.44%, PV(+)=98.15%; PV(–)=57.14%; OR=37.86. DE indicators for patients of group III: sensitivity — 91.66%, specificity — 91.0%, accuracy — 91.66%, PV(+)=100.0%.DISCUSSION: Ultrasound imaging of acute osteomyelitis in children of group Ia included nonspecific changes in periarticular tissues and had the lowest diagnostic accuracy (75%). Diagnostic accuracy increased in group Ib to 85% due to initial structural changes in the zone of preliminary calcification and hyaline cartilage of the epiphysis. Disease progression in group II was characterized by more distinct structural changes in the metaphysis with an increase in diagnostic accuracy to 93%. In patients of group III, the highest rates of diagnostic accuracy (91.67%) were obtained due to visualization of destructive changes in the epiphysis, metaphysis and zone of preliminary calcification.CONCLUSION: The ability to detect ultrasound signs of acute hematogenous metaepiphyseal osteomyelitis in children will allow the use of this method in the early diagnosis for the timely selection of an adequate treatment tactics.ВВЕДЕНИЕ: Своевременная и эффективная диагностика остеомиелита составляет основу успешной терапии, в то же время проблема установления данной патологии, особенно на ранних стадиях развития процесса, окончательно не решена. ЦЕЛЬ: Разработать ультразвуковую семиотику метаэпифизарного остеомиелита у детей раннего возраста в зависимости от длительности заболевания.МАТЕРИАЛ И МЕТОДЫ: Обследовано 108 детей от 1 мес и до 2 лет, мальчики — 65% (70/108), девочки — 35 (38/108). От 2 до 8 месяцев — 57% (62/108), новорожденные — 26% (27/108). Остальные дети: 12% (13/108) — 9–12 мес, 5% (6/108) — 1–2 года. Всем детям проводились рентгенография и ультразвуковое исследование. Диагноз остеомиелита был верифицирован при выполнении пункции сустава (n=102), костной пункции (n=57), вскрытии параартикулярной флегмоны (n=12). Статистика: обработка результатов исследования проводилась с помощью пакета прикладных программ Statistica 13.0 (TIBCO SoftwareInc, 2017). Для оценки эффективности ультразвукового исследования в диагностике острого остеомиелита рассчитывались диагностическая эффективность и прогностическая ценность положительного или отрицательного результатов, проводился расчет отношения правдоподобия.РЕЗУЛЬТАТЫ: Выделено три группы в зависимости от сроков заболевания на момент поступления в стационар: Iа группа — 1–3 суток, Iб группа — 4–7 суток, II группа — 8–14 суток, III группа — 15–21 суток от начала заболевания. Показатели ДЭ пациентов Iа группы: чувствительность — 81,8%, специфичность — 60,0%, точность — 75%, ПЦ(+)=81,82%; ПЦ(–)=60,00%; ОП=4,50. Показатели ДЭ пациентов Iб группы: чувствительность — 86,6%, специфичность — 66,6%, точность — 80,95%, ПЦ(+)=87,5%; ПЦ(–)=60,00%; ОП=7,00. Показатели ДЭ пациентов II группы: чувствительность — 92,98%, специфичность — 80,0%, точность — 93,44%, ПЦ(+)=98,15%; ПЦ(–)=57,14%; ОП=37,86. Показатели ДЭ пациентов III группы: чувствительность — 91,66%, специфичность — 91,0%, точность — 91,66%, ПЦ(+)=100,0%.ОБСУЖДЕНИЕ: Ультразвуковые признаки острого остеомиелита у детей Iа группы включали неспецифические изменения параартикулярных тканей и характеризовались наиболее низкой диагностической точностью (75%). Диагностическая точность возрастала в группе Iб до 85% за счет начальных структурных изменений в зоне предварительного обызвествления и гиалиновом хряще эпифиза. Прогрессирование заболевания в группе II характеризовалось более отчетливыми структурными изменениями в метафизе с повышением диагностической точности до 93%. У пациентов III группы были получены наиболее высокие показатели диагностической точности (91,67%) за счет визуализации деструктивных изменений в эпифизе, метафизе и зоне предварительного обызвествления.ЗАКЛЮЧЕНИЕ: Возможность обнаружения ультразвуковых признаков острого гематогенного метаэпифизарного остеомиелита у детей позволит использовать данный метод на ранних этапах диагностики для своевременного выбора адекватной тактики лечения

Effect of Dopants on Zirconia Stabilization—An X-ray Absorption Study: I, Trivalent Dopants

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65562/1/j.1151-2916.1994.tb06964.x.pd

Homogeneously derived transit timings for 17 exoplanets and reassessed TTV trends for WASP-12 and WASP-4

We homogeneously analyse ∼3.2 × 105 photometric measurements for ∼1100 transit lightcurves belonging to 17 exoplanet hosts. The photometric data cover 16 years 2004–2019 and include amateur and professional observations. Old archival lightcurves were reprocessed using up-to-date exoplanetary parameters and empirically debiased limb-darkening models. We also derive self-consistent transit and radial-velocity fits for 13 targets. We confirm the nonlinear TTV trend in the WASP-12 data at a high significance, and with a consistent magnitude. However, Doppler data reveal hints of a radial acceleration about ( − 7.5 ± 2.2) m/s/yr, indicating the presence of unseen distant companions, and suggesting that roughly 10 per cent of the observed TTV was induced via the light-travel (or Roemer) effect. For WASP-4, a similar TTV trend suspected after the recent TESS observations appears controversial and model-dependent. It is not supported by our homogeneus TTV sample, including 10 ground-based EXPANSION lightcurves obtained in 2018 simultaneously with TESS. Even if the TTV trend itself does exist in WASP-4, its magnitude and tidal nature are uncertain. Doppler data cannot entirely rule out the Roemer effect induced by possible distant companions

Transit timing analysis of the exoplanet TrES-5 b. Possible existence of the exoplanet TrES-5 c

peer reviewedIn this work, we present transit timing variations detected for the exoplanet TrES-5b. To obtain the necessary amount of photometric data for this exoplanet, we have organized an international campaign to search for exoplanets based on the transit-timing variation (TTV) method and as a result of this we collected 30 new light curves, 15 light curves from the Exoplanet Transit Database (ETD) and 8 light curves from the literature for the timing analysis of the exoplanet TrES-5b. We have detected timing variations with a semi-amplitude of A≈ 0.0016 d and a period of P≈ 99 d. We carried out the N-body modelling based on the three-body problem. The detected perturbation of TrES-5b may be caused by a second exoplanet in the TrES-5 system. We have calculated the possible mass and resonance of the object: M ≈ 0.24MJup at a 1:2 Resonance. © 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society.RSF: 14-50-0004

Исследование и верификация скоростных моделей земной коры методами математического моделирования и активной сейсмологии

The article discusses a comparison of theoretical seismograms for two velocity models of the Earth's crust and P-wave arrival times estimated from experimental vibration seismograms for the 400-km long section of the Baikal–Ulaanbaatar profile. The theoretical seismograms were obtained by mathematical simulation of wave fields using the Earth's crust velocity models based on the data of the BEST and PASSCAL experiments. Vibration seismograms were obtained by measuring the wave field of a CVO-100 vibrator in the SB RAS Southern Baikal polygon. In the experiments, the vibration seismograms show that arrival times in the P-wave group correspond to the values for waves of large amplitudes in the theoretical seismograms. The P-wave arrival times in the theoretical seismograms of the BEST experiment are compared to the values in the experimental vibration seismograms for the 400-km long section of the Baikal–Ulaanbaatar profile. This comparison shows that the arrival times of maximum amplitude waves correspond to the theoretical hodographs of waves with velocities of 6.25–6.80 km/sec in the BEST experiment velocity model. At the same time, the experimental data set does not contain arrival times corresponding to longitudinal waves with Vp=7.25 km/sec, which are related to an assumed layer (more than 10 km thick) in the lower crust for the BEST experiment velocity model. In the experiments, the P-wave arrival times in the vibration seismograms correspond to the P-wave arrival times in the theoretical seismograms of the PASSCAL experiment throughout the entire 400-km long section of the Baikal–Ulaanbaatar profile. It is thus confirmed that the average values of the wave velocities in the PASSCAL velocity model have been reliably estimated. It should be noted that the experimental values of the arrival times of the first wave in the P-wave group are in agreement with the first arrival times in the hodographs of the theoretical seismograms for the velocity model in the PASSCAL experiment considering the distances from the source in a range of 65–380 km.Представлены результаты сравнения теоретических сейсмограмм для двух скоростных моделей земной коры и данных о временах вступлений Р-волн на экспериментальных вибрационных сейсмограммах на 400-километровом участке профиля Байкал – Улан-Батор. Теоретические сейсмограммы получены методами математического моделирования волновых полей для скоростных моделей земной коры, построенных по данным экспериментов BEST и PASSCAL. Вибрационные сейсмограммы получены при измерении волнового поля вибратора ЦВО-100 Южно-Байкальского полигона СО РАН. Экспериментальные значения времен вступлений в группе Р-волн на вибрационных сейсмограммах соответствуют значениям на теоретических сейсмограммах для волн большой амплитуды. Cравнение теоретических сейсмограмм эксперимента BEST и данных о временах вступлений Р-волн на экспериментальных вибрационных сейсмограммах на 400-кило­метровом участке профиля Байкал – Улан-Батор показывает, что экспериментальные времена вступлений волн максимальной амплитуды соответствуют теоретическим годографам волн со скоростью 6.25–6.80 км/с скоростной модели эксперимента BEST. Вместе с тем экспериментальные данные не содержат времен вступлений, соответствующих продольным волнам со скоростью Vp=7.25 км/с, связанных с предполагаемым слоем мощностью более 10 км в нижней коре в скоростной модели эксперимента BEST. Экспериментальные значения времен вступлений волн в группе Р-волн вибрационных сейсмограмм находятся в области времен вступлений волн на теоретических сейсмограммах эксперимента PASSCAL на всем протяжении 400-километрового профиля. Это свидетельствует о надежном определении средних значений скоростей волн в скоростной модели эксперимента PASSCAL. Следует отметить, что экспериментальные значения времен вступлений первой волны в группе Р-волн согласуются с временами первых вступлений на годографах теоретических сейсмограмм для скоростной модели эксперимента PASSCAL в диапазоне расстояний от 65 до 380 км от источника