Applied Physics Institute Research Articles

The detection of gravitational waves: the contribution of the Applied Physics Institute, Russian Academy of Sciences

September 14, 2015 marked the day that the LIGO collaboration recorded a gravitational-wave signal arriving from the merger of two black holes that occurred 1.3 billion years ago. The LIGO detector is based on a Michelson interferometer with an arm length of 4 km. The achieved sensitivity makes it possible to detect a change of the arm length smaller than 10−19 meter. We discuss the physical problems that were solved in order to achieve this unprecedented sensitivity. The most essential contribution of the Applied Physics Institute, Russian Academy of Sciences, to the LIGO detector is the invention of unique Faraday isolators that operate with high laser radiation power. The absorption of radiation in a magneto-active medium unavoidably causes it to heat up and thermally induces polarization and phase distortion of the laser beam. This article presents an analysis of all the distortions of the laser beam from the viewpoint of the degradation of the parameters of the isolator. The mechanisms and key physical quantities responsible for the various forms of the distortions have been determined. The existing methods of compensating and suppressing parasitic thermal effects are described in detail.

Effect of the local corticosteroid therapy and Tacrolimus on the morphological and functional skin indices of different phototypes

Objective. To assess the effect of local corticosteroid therapy and Tacrolimus on the morphological and functional skin indices of different phototypes. Materials and methods. The authors conducted a complex assessment of the morphological and functional skin condition of different phototypes among healthy volunteers under the impact of corticosteroids and Tacrolimus. The study involved 20 healthy volunteers (10 people of the 1st and 2nd skin phototypes and 10 people of the 5th and 6th skin phototypes; 14 males and 6 females; mean age: 2з years). The morphological condition of the skin was assessed with the use of optical coherent tomography (Applied Physics Institute, Russian Academy of Sciences, Nizhny Novgorod) while the functional condition was assessed with the use of Multi Skin Test Center MC 750 (Courage+Khazaka Cologne, Germany). Results. The authors revealed that the application of local corticosteroids is accompanied with a reliable reduction in the epidermis thickness developing earlier in the subjects belonging to the 5th and 6th phototypes and, at the same time, increased transepidermal water loss and reduced corneous layer humidity. An increase in the corneous layer thickness accompanied by an increase in the humidity factor was registered in all phototypes in the areas where Tacrolimus was applied. It is possible to select the correct tactics of the anti-inflammatory therapy on the basis of monitoring the morphological and functional skin condition in the process of applying local corticosteroids: to determine the optimum duration of the corticosteroid therapy and switch to calcineurin inhibitors on a timely basis when there is a need to perform an antiinflammatory therapy to achieve the maximum efficacy with the minimum risk of complication development.

Improved laboratory rest frequency measurements and pressure shift and broadening parameters for the J = 2 - 1 and J = 3 - 2 rotational transitions of CO

The J=2←1, 3←2, and the 4←3 rotational transitions of CO have been measured using the RAD-2 microwave spectrometer at the Applied Physics Institute in Nizhny Novgorod. Pressure shift and broadening parameters were measured for the J=2←1 and J=3←2 transitions. This was done with CO (self broadening) and CO 2 (foreign gas-broadening). The new laboratory rest frequency measurements are accurate to ±2 kHz (2 σ uncertainty)