Frequency behavior of Raman coupling coefficient in glasses

Low-frequency Raman coupling coefficient of 11 different glasses is evaluated. It is found that the coupling coefficient demonstrates a universal linear frequency behavior near the boson peak maximum and a superlinear behavior at very low frequencies. The last observation suggests vanishing of the coupling coefficient when frequency tends to zero. The results are discussed in terms of the vibration wavefunction that combines features of localized and extended modes.Comment: 8 pages, 9 figure

Periodic orbit spectrum in terms of Ruelle--Pollicott resonances

Fully chaotic Hamiltonian systems possess an infinite number of classical solutions which are periodic, e.g. a trajectory ``p'' returns to its initial conditions after some fixed time tau_p. Our aim is to investigate the spectrum tau_1, tau_2, ... of periods of the periodic orbits. An explicit formula for the density rho(tau) = sum_p delta (tau - tau_p) is derived in terms of the eigenvalues of the classical evolution operator. The density is naturally decomposed into a smooth part plus an interferent sum over oscillatory terms. The frequencies of the oscillatory terms are given by the imaginary part of the complex eigenvalues (Ruelle--Pollicott resonances). For large periods, corrections to the well--known exponential growth of the smooth part of the density are obtained. An alternative formula for rho(tau) in terms of the zeros and poles of the Ruelle zeta function is also discussed. The results are illustrated with the geodesic motion in billiards of constant negative curvature. Connections with the statistical properties of the corresponding quantum eigenvalues, random matrix theory and discrete maps are also considered. In particular, a random matrix conjecture is proposed for the eigenvalues of the classical evolution operator of chaotic billiards

Universal and non-universal features of glassy relaxation in propylene carbonate

It is demonstrated that the susceptibility spectra of supercooled propylene carbonate as measured by depolarized-light-scattering, dielectric-loss, and incoherent quasi-elastic neutron-scattering spectroscopy within the GHz window are simultaneously described by the solutions of a two-component schematic model of the mode-coupling theory (MCT) for the evolution of glassy dynamics. It is shown that the universal beta-relaxation-scaling laws, dealing with the asymptotic behavior of the MCT solutions, describe the qualitative features of the calculated spectra. But the non-universal corrections to the scaling laws render it impossible to achieve a complete quantitative description using only the leading-order-asymptotic results.Comment: 37 pages, 16 figures, to be published in Phys. Rev.

Surface Enhanced Raman Scattering of Light by ZnO Nanostructures

Raman scattering (including nonresonant, resonant, and surface enhanced scattering) of light by optical and surface phonons of ZnO nanocrystals and nanorods has been investigated. It has been found that the nonresonant and resonant Raman scattering spectra of the nanostructures exhibit typical vibrational modes, E-2(high) and A(1)(LO), respectively, which are allowed by the selection rules. The deposition of silver nanoclusters on the surface of nanostructures leads either to an abrupt increase in the intensity (by a factor of 10(3)) of Raman scattering of light by surface optical phonons or to the appearance of new surface modes, which indicates the observation of the phenomenon of surface enhanced Raman light scattering. It has been demonstrated that the frequencies of surface optical phonon modes of the studied nanostructures are in good agreement with the theoretical values obtained from calculations performed within the effective dielectric function model

Propylene Carbonate Reexamined: Mode-Coupling β\beta Scaling without Factorisation ?

The dynamic susceptibility of propylene carbonate in the moderately viscous regime above $T_{\rm c}$ is reinvestigated by incoherent neutron and depolarised light scattering, and compared to dielectric loss and solvation response. Depending on the strength of $\alpha$ relaxation, a more or less extended $\beta$ scaling regime is found. Mode-coupling fits yield consistently $\lambda=0.72$ and $T_{\rm c}=182$K, although different positions of the susceptibility minimum indicate that not all observables have reached the universal asymptotics

Разнообразие современных методов детекции и типирования вируса папилломы человека

Cervical cancer is one of the most common types of cancer. Human papillomavirus (HPV) infection is a proven cause of cervical cancer, and there is growing evidence that oncogenic HPV types causes most cervical, penile, vulvar, vaginal, anal, and oropharyngeal cancers and precancerous conditions, whereas nononcogenic, low-risk HPV infection causes genital warts and recurrent respiratory papillomatosis. New promising methods for detection and typing of HPV appear daily: mass spectrometry genotyping of human papillomavirus based on nanomaterials high-efficiency selective enichment, next-generation sequencing, CRISPR / Cas9, and others. Nevertheless, currently quantitative PCR is still better than the newest methods because of the following advantages: it is relatively easy to use, there are many reliable, tested, and registered methods based on it, it is a relatively cheap method (inexpensive reagents and instruments), a large number of laboratories is equipped with instrumentation and trained personnel for real-time PCR. It is all combined with high sensitivity and specificity of this method.Рак шейки матки - один из самых распространенных видов рака. Инфицирование вирусом папилломы человека (ВПЧ) - доказанная причина возникновения рака шейки матки, к тому же накапливается все больше доказательств, что онкогенные типы ВПЧ вызывают большую часть рака и предраковых заболеваний полового члена, вульвы, влагалища, анального канала и ротоглотки, в то время как не онкогенные типы ВПЧ могут быть причиной генитальных бородавок и рецидивирующего респираторного папилломатоза. С каждым днем появляются все новые многообещающие методики детекции и типирования ВПЧ: масс-спектрометрия с высокоэффективным обогащением с помощью наноматериалов, секвенирование нового поколения, CRISPR/Cas9 и другие. Тем не менее на сегодняшний день количественная ПЦР все еще выигрывает у новейших методов поскольку обладает следующими преимуществами: относительно проста в применении, существует много надежных, проверенных и зарегистрированных методик для ее проведения, это относительно дешевый метод (недорогие реагенты и приборы), большое количество лабораторий оснащены приборами и обученным персоналом для проведения ПЦР в реальном времени. И все это сочетается с высокой чувствительностью и специфичностью

ИЗУЧЕНИЕ ВЛИЯНИЯ СТРЕССА НА МОРФОЛОГИЧЕСКИЕ ИЗМЕНЕНИЯ В ГИППОКАМПЕ ПРИ ХИРУРГИЧЕСКИХ ВМЕШАТЕЛЬСТВАХ В ОБЛАСТИ НОСА

Objective - to study the morphological changes in the hippocampus of the rat brain following modeling septoplasty. Material and methods. The study was conducted on 80 adult male rats. In the experimental groups1 and 2, premedica tion with Phenazepamum was carried out. Group 1 included 30 rats subjected to local infiltration anesthesia with 2 % lidocaine solution; group 2 included 30 rats subjected to local infiltration anesthesia with 2 % solution of articain & epinephrine (0,5 mg/100 ml) and postoperative analgesia with diclofenac sodium solution for 6 days after surgery. Groups 3 and 4 were controls and included 10 animals each. In groups 1-3, fixation of the brain was performed prior to trepanation; in group 4, similar fixation was not performed and artifact dark neurons were counted. The number of dark neurons in the hippocampus was counted on hematoxylin-eosin stained brain sections on days 2, 6 and 14 after surgery. Results. In group 2, in the CA1, CA2, CA3 and DG zones, there were fewer dark neurons (DN) on day 6 compared with group 1. On 14th day, the number of DN in areas CA1 and CA2 was comparable in groups 2 and 3. In group 4, compared with group 3, the number of DN was greater in all studied hippocampal zones. Conclusion. The quantitative changes of DN in different zones of the hippocampus may indicate the severity of surgical stress following simulation of septoplasty under different types of anesthesia.Цель - изучить морфологические изменения в гиппокампе мозга крыс при моделировании пластики носовой перегородки. Материалы и методы. Работа выполнена на 80 половозрелых крысах-самцах. В экспериментальных 1-йи 2-й группе проводили премедикацию раствором фенозепама. 1-я группа включала 30 крыс, подвергнутых местной инфильтрационной анестезии 2 % раствором лидокаина; 2-я группа - 30 крыс, подвергнутых местной инфильтрационной анестезии 2 % раствором артикаина и эпинефрина (0,5 мг/100 мл), послеоперационной аналгезии раствором диклофенака натрия в течение 6 сут после операции. 3-яи 4-я группа были контрольными и включали по 10 животных. В 1-3-й группе проводилась предтрепанационная фиксация головного мозга, в 4-й группе подобной фиксации не проводилось и подсчитывались артефактные темные нейроны (ТН). Изучали число ТН в гиппокампе на срезах головного мозга, окрашенных гематоксилином и эозином, на 2-, 6-еи 14-е сутки после операции. Результаты. Во 2-й группе в зонах СА1, СА2, СА3 и DG наблюдали меньшее число ТН по сравнению с 1-й группой на 6-е сутки. На 14-е сутки число ТН во 2-йи 3-й группе было сопоставимо в зонах СА1 и СА2. В 4-й группе по сравнению с 3-й группой число ТН было больше во всех исследованных зонах гиппокампа. Вывод. Количественные изменения ТН в различных зонах гиппокампа могут свидетельствовать о выраженном хирургическом стрессе во время моделирования септопластики при различном анестезиологическом пособии