Saturation effects in the sub-Doppler spectroscopy of Cesium vapor confined in an Extremely Thin Cell

Saturation effects affecting absorption and fluorescence spectra of an atomic vapor confined in an Extremely Thin Cell (cell thickness $L < 1 \mu m$) are investigated experimentally and theoretically. The study is performed on the $D_{2}$ line ($\lambda ~= ~852 nm)$ of $Cs$ and concentrates on the two situations $L = \lambda /2$ and $L =\lambda$, the most contrasted ones with respect to the length dependence of the coherent Dicke narrowing. For $L = \lambda /2$, the Dicke-narrowed absorption profile simply broadens and saturates in amplitude when increasing the light intensity, while for $L =\lambda$, sub-Doppler dips of reduced absorption at line-center appear on the broad absorption profile. For a fluorescence detection at $L =\lambda$, saturation induces narrow dips, but only for hyperfine components undergoing a population loss through optical pumping. These experimental results are interpreted with the help of the various existing models, and are compared with numerical calculations based upon a two-level modelling that considers both a closed and an open system.Comment: 11 pages, 12 figure

Migrations and formation of the Volga Bulgarian State (VIII-X C.): Results of the complex analysis

© Serials Publications. The formation of the medieval Bulgarian state has always attracted the attention of researchers, as this event provided the Volga-Ural region's breakthrough to civilization and became an important stage in social, cultural and ethno-political history of the region. Relocation of the Bulgarian tribes living on the right bank of the Middle Don at the end of VII century to the Middle Volga was determining in this process. There they contacted with different communities and tribes, both local and from the Central Asia. Bulgarians sought to create their own statehood. With the weakening of the Khazars' power and the sharp increasing of the international trade on the Great Volga route in the IX century the Bulgarians were gradually establishing their hegemony over the population of the Middle Volga in the confrontation with two other tribal associations. A new phase of folding the foundations of the Bulgarian feudal state began in early X century. During this period there was an active urban growth and international trade along the Great Volga route. At the same time Islam was adopted as the state religion. Bulgarians led by the elteber Almysh (who became a supreme corporate landowner) started to be the military-service class in the new state.922 was the year of diplomatic recognition of Bulgaria. It exchanged embassies with the Baghdad Caliphate. Cities were developing as political, administrative, trade and handicraft centers. During this period a number of elements from the other ethnic groups (Slavic, Finno-Ugrian and Scandinavian) enter into the Bulgarian squad and its own syncretic culture is produced. But in 940two emirates Bulgar and Suvar were formed. Their state institutions strengthened and Islam spread. The defeat of the Khazar Khaganate (in 980) led to strengthening of the Bulgarians united in a Bulgarian state

Organizational and economic directions of competitive recovery of Russian pharmaceutical enterprises

The urgency of the analyzed issue is due to the fact that the sustainable development of the economy of any country is the most important level of public health, which in turn, is conditioned by providing high quality pharmaceutical products. This is determined by the effective activity of the pharmaceutical industry, its competitiveness. Thus, the study of the competitiveness of Russian pharmaceutical enterprises, the development directions of its improvement should contribute to the sustainable development of the Russian economy. The article is focused on the development of organizational and economic ways of competitive recovery of the pharmaceutical industry. The leading approach to the study of this issue is an analytical approach that allows identifying the main directions of competitive recovery of the pharmaceutical industry. The results of the article: the study of possible organizational and economic ways of competitive recovery of Russian companies in the pharmaceutical industry, the algorithm of directions of its increase. The made recommendations have been tested in a number of Russian companies in the pharmaceutical industry. The article date may be useful in the management of the pharmaceutical industry now, as well as for understanding the specifics of the domestic pharmaceutical industry. © 2016 Ashmarina et al

Computer Experiments for Function Approximations

This research project falls in the domain of response surface methodology, which seeks cost-effective ways to accurately fit an approximate function to experimental data. Modeling and computer simulation are essential tools in modern science and engineering. A computer simulation can be viewed as a function that receives input from a given parameter space and produces an output. Running the simulation repeatedly amounts to an equivalent number of function evaluations, and for complex models, such function evaluations can be very time-consuming. It is then of paramount importance to intelligently choose a relatively small set of sample points in the parameter space at which to evaluate the given function, and then use this information to construct a surrogate function that is close to the original function and takes little time to evaluate. This study was divided into two parts. The first part consisted of comparing four sampling methods and two function approximation methods in terms of efficiency and accuracy for simple test functions. The sampling methods used were Monte Carlo, Quasi-Random LP{sub {tau}}, Maximin Latin Hypercubes, and Orthogonal-Array-Based Latin Hypercubes. The function approximation methods utilized were Multivariate Adaptive Regression Splines (MARS) and Support Vector Machines (SVM). The second part of the study concerned adaptive sampling methods with a focus on creating useful sets of sample points specifically for monotonic functions, functions with a single minimum and functions with a bounded first derivative

Dynamics of false vacuum bubbles in Brans-Dicke theory

We study the dynamics of false vacuum bubbles in the Brans-Dicke theory of gravity by using the thin shell or thin wall approximation. We consider a false vacuum bubble that has a different value for the Brans-Dicke field between the inside false vacuum region and the outside true vacuum region. Within a certain limit of field values, the difference of field values makes the effective tension of the shell negative. This allows new expanding false vacuum bubbles to be seen by the outside observer, which are disallowed in Einstein gravity.Comment: 29 pages, 20 figure

Sub-Doppler spectroscopy of Rb atoms in a sub-micron vapor cell in the presence of a magnetic field

We report the first use of an extremely thin vapor cell (thickness ~ 400 nm) to study the magnetic-field dependence of laser-induced-fluorescence excitation spectra of alkali atoms. This thin cell allows for sub-Doppler resolution without the complexity of atomic beam or laser cooling techniques. This technique is used to study the laser-induced-fluorescence excitation spectra of Rb in a 50 G magnetic field. At this field strength the electronic angular momentum J and nuclear angular momentum I are only partially decoupled. As a result of the mixing of wavefunctions of different hyperfine states, we observe a nonlinear Zeeman effect for each sublevel, a substantial modification of the transition probabilities between different magnetic sublevels, and the appearance of transitions that are strictly forbidden in the absence of the magnetic field. For the case of right- and left- handed circularly polarized laser excitation, the fluorescence spectra differs qualitatively. Well pronounced magnetic field induced circular dichroism is observed. These observations are explained with a standard approach that describes the partial decoupling of I and J states