Correlated stimulated photon echo signals under three-photon femtosecond excitation of CdSe-CdS colloidal quantum dots

© 2016 Astro Ltd.The possibility and conditions of the correlated signals of stimulated photon echo (SPE) generation under three-photon femtosecond excitation of a sample, which is an ensemble of N semiconductor nanoparticles, are investigated. Each of these nonoparticles consists of a CdSe core covered by a CdS shell. The phase matching conditions for correlated SPE signal formation in such a sample are obtained

Correlated signals of the accumulated photon echo on CdSe - CdS quantum dots

The possibility of an observation of correlated signals of the accumulated photon echo under a three-photon excitation of a sample, which is an ensemble of semiconductor nanoparticles of "core - shell" type, by a femtosecond radiation of Ti:Sa laser is discussed. The phase matching conditions of such signals are obtained

Femtosecond photon echo and four-wave mixing in dye-doped polymer films, semiconductors and heterostructures

A review of femtosecond experiments on photon echo (PE) and four-wave mixing (FWM) performed at room temperature is presented. The Weiner-Ippen technique of FWM spectroscopy is demonstrated in dye-doped polymer films (such as polyvinilbutural doped with phthalocyanine), semiconductors (CdS) and heterostructures (GaAs/AlGaAs). The experimental setup used in these experiments is described. The dephasing times are estimated and the relaxation mechanisms are discussed. © 2014 Astro Ltd

Femtosecond correlated transient holography in CdS crystal under two-quantum excitation

This paper is devoted to the discussion of a possibility of the femtosecond correlated transient holograms recording in CdS crystal under two-quantum excitation

円山クリニック（かかりつけ医ご紹介）

This paper is devoted to the discussion of a possibility of the femtosecond correlated transient holograms recording in CdS crystal under two-quantum excitation

Direct Evidence of Two Superconducting Gaps in FeSe0.5_{0.5}Te0.5_{0.5}: SnS-Andreev Spectroscopy and Lower Critical Field

We present direct measurements of the superconducting order parameter in nearly optimal FeSe$_{0.5}$Te$_{0.5}$ single crystals with critical temperature $T_C \approx 14$ K. Using intrinsic multiple Andreev reflection effect (IMARE) spectroscopy and measurements of lower critical field, we directly determined two superconducting gaps, $\Delta_L \approx 3.3 - 3.4$ meV and $\Delta_S \approx 1$ meV, and their temperature dependences. We show that a two-band model fits well the experimental data. The estimated electron-boson coupling constants indicate a strong intraband and a moderate interband interaction

Femtosecond coherent spectroscopy of four-wave mixing and the spectroscopy of transient gratings in GaAs/AlGaAs semiconductor heterostructures at room temperature

Results from femtosecond coherent spectroscopy of four-wave mixing in GaAs/AlGaAs semiconductor heterostructures at room temperature are presented. Electron diffusivities and their spins are found via spectroscopy of transient gratings. Investigations in the field of spin transport in GaAs/AlGaAs heterostructures are performed with the aim of their possible use in spintronics applications. © 2014 Allerton Press, Inc

Состояние минеральной плотности кости у пожилых пациентов с остеоартрозом

Objective: to study bone mineral density (BMD) in elderly patients with different clinical forms of osteoarthrosis (OA). Patients and methods. A hundred and fifty-five patients above 65 years of age, diagnosed as having OA according to the criteria developed by R. Altman were examined. In all the patients, anthropometric indices, duration of the disease, and degree of functional impairment were assessed and joint X-ray study and densitometry were made. According to the clinical form of the disease, the patients were divided into 3 groups (with signs of gonarthrosis, oligoarthrosis of the knee and hip joints, and polyosteoarthrosis). Results. Both the clinical and anthropometric characteristics of patients facilitated the development of osteopenia. Involvement of a larger number of joints into a pathological process was followed by a significant BMD reduction in the predominant number of patients with OA. With the more progressive X-ray stage of the disease, a significantly higher BMD was observed in the distal forearm of patients from all groups. The patients aged 75 years or older who had gonarthrosis and polyosteoarthrosis showed a significant reduction in BMD as compared with those of less than 75 years of age. A greater reduction in the T test was shown to correspond to less body weight. The examinees' inactivity correlated with decreased BMD. In patients with polyosteoarthritis, early onset and longer menopause negatively affected BMD in the distal forearm. Conclusion. Reduced distal forearm BMD in elderly patients with OA is associated with patients' older age and a longer menopause, less body weight, early menopause, and no regular exercises. Progression of the X-ray stage of OA correlates with increased bone density.Цель исследования - изучение состояния минеральной плотности кости (МПК) у пожилых больных с различными клиническими формами остеоартроза (ОА). Материал и методы. Обследованы 155 больных старше 65 лет с диагнозом ОА, соответствующим критериям R. Altman. У всех больных оценивали антропометрические показатели, длительность заболевания, степень функциональной недостаточности, проводили рентгенологическое исследование суставов, денситометрию. В зависимости от клинической формы заболевания пациенты были разделены на три группы (с признаками гонартроза, олигоартроза коленных и тазобедренных суставов, полиостеоартроза). Результаты исследования. Развитию остеопении способствовали как клинические, так и антропометрические характеристики пациентов. Вовлечение в патологический процесс большего числа суставов сопровождалось достоверным снижением МПК у преобладающего числа больных ОА. При увеличении рентгенологической стадии заболевания отмечена достоверно более высокая МПК дистального отдела предплечья у больных всех групп. У больных с гонартрозом и полиостеоартрозом в возрасте 75 лет и старше наблюдалось достоверное снижение МПК по сравнению с данными пациентов моложе 75 лет. Показано, что меньшей массе тела соответствовало большее снижение Т-критерия во всех группах. Отсутствие физических нагрузок у обследованных коррелировало со снижением МПК. У пациенток с полиостеоартрозом раннее начало и увеличение продолжительности менопаузы отрицательно влияли на МПК дистального отдела предплечья. Заключение. Снижение МПК дистального отдела предплечья у пожилых пациентов с ОА ассоциируется с увеличением возраста больных и длительностью менопаузы, уменьшением массы тела, наличием ранней менопаузы и отсутствием регулярных физических нагрузок. Прогрессирование рентгенологической стадии ОА коррелирует с увеличением показателей костной плотности

Entangled femtosecond free induction signals in a cadmium sulfide crystal at room temperature

Entangled free induction decay (EFID) femtosecond signals are experimentally observed for the first time at a wavelength of 790 nm in a cadmium sulfide (CdS) crystal in the two-photon absorption (TPA) regime upon excitation by two crossed (angle, 60°) laser beams. The sample emitted two EFID signals simul- taneously in opposite directions. The signals were diffracted by nonequilibrium electric polarization gratings induced by two laser beams in accordance with the laws of energy and momentum conservation. The possi- bility of exciting EFID signals in the three-photon absorption regime is discussed. © Allerton Press, Inc., 2012

Electron dynamics at GaAs-AlGaAs heterojunction studied by ultrafast spectroscopy

In this letter the electron and spin dynamics at GaAs/AlGaAs heterojunction was studied by ultrafast spectroscopy techniques (photon echo and transient grating studies). Relaxation times and diffusion coefficients of photoexcited electrons and spins were obtained using pure optical setup. The estimated spin diffusion coefficient value of 160 cm2/s is relatively high and comparable to the electron diffusion coefficient of 200 cm2/s. This feature makes GaAs/AlGaAs heterosructure a promising material for practical application in semiconductor spintronics. © Published under licence by IOP Publishing Ltd