Strongly aligned molecules inside helium droplets in the near-adiabatic regime

Iodine (I$_2$) molecules embedded in He nanodroplets are aligned by a 160 ps long laser pulse. The highest degree of alignment, occurring at the peak of the pulse and quantified by $\langle \cos^2 \theta_{2D} \rangle$, is measured as a function of the laser intensity. The results are well described by $\langle \cos^2 \theta_{2D} \rangle$ calculated for a gas of isolated molecules each with an effective rotational constant of 0.6 times the gas-phase value, and at a temperature of 0.4 K. Theoretical analysis using the angulon quasiparticle to describe rotating molecules in superfluid helium rationalizes why the alignment mechanism is similar to that of isolated molecules with an effective rotational constant. A major advantage of molecules in He droplets is that their 0.4 K temperature leads to stronger alignment than what can generally be achieved for gas phase molecules -- here demonstrated by a direct comparison of the droplet results to measurements on a $\sim$ 1 K supersonic beam of isolated molecules. This point is further illustrated for more complex system by measurements on 1,4-diiodobenzene and 1,4-dibromobenzene. For all three molecular species studied the highest values of $\langle \cos^2 \theta_{2D} \rangle$ achieved in He droplets exceed 0.96.Comment: 11 pages, 8 figure

The Methods to Improve Quality of Service by Accounting Secure Parameters

A solution to the problem of ensuring quality of service, providing a greater number of services with higher efficiency taking into account network security is proposed. In this paper, experiments were conducted to analyze the effect of self-similarity and attacks on the quality of service parameters. Method of buffering and control of channel capacity and calculating of routing cost method in the network, which take into account the parameters of traffic multifractality and the probability of detecting attacks in telecommunications networks were proposed. The both proposed methods accounting the given restrictions on the delay time and the number of lost packets for every type quality of service traffic. During simulation the parameters of transmitted traffic (self-similarity, intensity) and the parameters of network (current channel load, node buffer size) were changed and the maximum allowable load of network was determined. The results of analysis show that occurrence of overload when transmitting traffic over a switched channel associated with multifractal traffic characteristics and presence of attack. It was shown that proposed methods can reduce the lost data and improve the efficiency of network resources.Comment: 10 pages, 1 figure, 1 equation, 1 table. arXiv admin note: text overlap with arXiv:1904.0520

Criminal Liability for Violation of the Quarantine Regime in the Conditions of the COVID-19 Pandemic

Infectio us diseases is the subject of increased attention, which causes concern in society throughout the world. In this context, and in order to implement preventive measures, democratisation and protection of human rights are increasingly combined with measures of state coercion. The new challenge today is the COVID-19 pandemic, recognised by the World Health Organisation. Today is pandemic has forced a qualitative rethink of approaches to responding to the health challenges of both individuals and nations. States have gradually begun to use a variety of health measures, including policy and legal instruments, to control the spread and effects of COVID-19. Some states have resorted to criminal law to apply it to health care to prevent infection with COVID-19. A comparative analysis of the features of criminal liability for violating the quarantine regime in the European Union and Ukraine showed the variability of the structures of crimes, however, the unity of difficulties in qualifying socially dangerous acts and, as a result, the impossibility of effective prosecution. It was stated that there was an urgent need for States to recognise that the new coronavirus was a serious health emergency, but that the criminalisation related to COVID-19 was a worrying trend towards prolonging human rights restrictions. Experts are increasingly questioning, in particular, the feasibility and effectiveness of existing criminal law measures on health care and their fragmentary compliance with internationally declared human rights standards, which in the long run will be the basis for the abolition of new criminalised components of crimes

Impurities in a one-dimensional Bose gas: the flow equation approach

A few years ago, flow equations were introduced as a technique for calculating the ground-state energies of cold Bose gases with and without impurities. In this paper, we extend this approach to compute observables other than the energy. As an example, we calculate the densities, and phase fluctuations of one-dimensional Bose gases with one and two impurities. For a single mobile impurity, we use flow equations to validate the mean-field results obtained upon the Lee-Low-Pines transformation. We show that the mean-field approximation is accurate for all values of the boson-impurity interaction strength as long as the phase coherence length is much larger than the healing length of the condensate. For two static impurities, we calculate impurity-impurity interactions induced by the Bose gas. We find that leading order perturbation theory fails when boson-impurity interactions are stronger than boson-boson interactions. The mean-field approximation reproduces the flow equation results for all values of the boson-impurity interaction strength as long as boson-boson interactions are weak.Comment: Re-submission to SciPost. Major changes are highlighte

Attractive interactions, molecular complexes, and polarons in coupled dipolar exciton fluids

Dipolar (or spatially indirect) excitons (IXs) in semiconductor double quantum well (DQW) subjected to an electric field are neutral species with a dipole moment oriented perpendicular to the DQW plane. Here, we theoretically study interactions between IXs in stacked DQW bilayers, where the dipolar coupling can be either attractive or repulsive depending on the relative positions of the particles. By using microscopic band structure calculations to determine the electronic states forming the excitons, we show that the attractive dipolar interaction between stacked IXs deforms their electronic wave function, thereby increasing the inter-DQW interaction energy and making the IX electrically polarizable. Many-particle effects interaction are addressed by considering the coupling between a single IX in one of the DQWs to a cloud of IXs in the other DQW, which is modeled either as a closed-packed lattice or as a continuum IX fluid. We find that the lattice model yields IX interlayer binding energies decreasing with increasing lattice density. This behavior is due to the dominating role of the intra-DQW dipolar repulsion, which prevents more than one exciton from entering the attractive region of the inter-DQW coupling. Finally, both models shows that the single IX distorts the distribution of IXs in the adjacent DQW, thus inducing the formation of an IX polaron. While the interlayer binding energy reduces with IX density for lattice polarons, the continuous polaron model predicts a non-monotonous dependence on density in semi-quantitative agreement with a recent experimental study [cf. Hubert {\it et al.}, Phys. Rev. {\bf X}9, 021026 (2019)].Comment: 12 figures, 12 page

Bond polarizability as a probe of local crystal fields in hybrid lead-halide perovskites

A rotating organic cation and a dynamically disordered soft inorganic cage are the hallmark features of hybrid organic-inorganic lead-halide perovskites. Understanding the interplay between these two subsystems is a challenging problem but it is this coupling that is widely conjectured to be responsible for the unique behaviour of photo-carriers in these materials. In this work, we use the fact that the polarizability of the organic cation strongly depends on the ambient electrostatic environment to put the molecule forward as a sensitive probe of local crystal fields inside the lattice cell. We measure the average polarizability of the C/N--H bond stretching mode by means of infrared spectroscopy, which allows us to deduce the character of the motion of the cation molecule, find the magnitude of the local crystal field and place an estimate on the strength of the hydrogen bond between the hydrogen and halide atoms. Our results pave the way for understanding electric fields in lead-halide perovskites using infrared bond spectroscopy

Diagnostics and evaluation of biliary deposit at ultrasound investigation

National college of gastroenterologists, hepatologist

Effective model for studying optical properties of lead-halide perovskites

We use general symmetry-based arguments to construct an effective model suitable for studying optical properties of lead-halide perovskites. To build the model, we identify an atomic-level interaction between electromagnetic fields and the spin degree of freedom that should be added to a minimally-coupled $\mathbf{k\cdot p}$ Hamiltonian. As an application, we study two basic optical characteristics of the material: the Verdet constant and the refractive index

Interparticle interactions:Energy potentials, energy transfer, and nanoscale mechanical motion in response to optical radiation

In the interactions between particles of material with slightly different electronic levels, unusually large shifts in the pair potential can result from photoexcitation, and on subsequent electronic excitation transfer. To elicit these phenomena, it is necessary to understand the fundamental differences between a variety of optical properties deriving from dispersion interactions, and processes such as resonance energy transfer that occur under laser irradiance. This helps dispel some confusion in the recent literature. By developing and interpreting the theory at a deeper level, one can anticipate that in suitable systems, light absorption and energy transfer will be accompanied by significant displacements in interparticle separation, leading to nanoscale mechanical motion

Generalized tuberculosis with long-term course in the guise of liver cirrhosis

Aim of investigation. To demonstrate unusual clinical symptoms and difficulties of diagnostics of disseminated tuberculous process.Material and methods. The 25 year-old patient, who was managed for 10 years for liver cirrhosis of nonspecified etiology, was investigated. The careful analysis of clinical presentation of disease, data of physical examination, results of radiological and other methods of diagnostics was carried out.Results. It was possible to suspect and subsequently to confirm disseminated tuberculosis with involvement of the lungs, the heart, pericardium, pleura, mesenteric lymph nodes, the liver; chronic right-sided tubercular pleurisy with pleurocirrhosis; constrictive pericarditis with signs of right ventricular failure; cardiac liver fibrosis (Pick's pseudocirrhosis); mixed portal hypertension.Conclusion. The detailed analysis of clinical presentation of disease, physical data and application of complex of visual and other methods of investigation expand potential of diagnostics of disseminated tuberculous process