Dislocation-induced superfluidity in a model supersolid

Motivated by recent experiments on the supersolid behavior of $^4$He, we study the effect of an edge dislocation in promoting superfluidity in a Bose crystal. Using Landau theory, we couple the elastic strain field of the dislocation to the superfluid density, and use a linear analysis to show that superfluidity nucleates on the dislocation before occurring in the bulk of the solid. Moving beyond the linear analysis, we develop a systematic perturbation theory in the weakly nonlinear regime, and use this method to integrate out transverse degrees of freedom and derive a one-dimensional Landau equation for the superfluid order parameter. We then extend our analysis to a network of dislocation lines, and derive an XY model for the dislocation network by integrating over fluctuations in the order parameter. Our results show that the ordering temperature for the network has a sensitive dependence on the dislocation density, consistent with numerous experiments that find a clear connection between the sample quality and the supersolid response.Comment: 10 pages, 6 figure

Notes on chiral hydrodynamics within effective theory approach

We address the issue of evaluating chiral effects (such as the newly discovered chiral separation) in hydrodynamic approximation. The main tool we use is effective theory which defines interaction in terms of chemical potentials $\mu,\mu_5$. In the lowest order in $\mu,\mu_5$ we reproduce recent results based on thermodynamic considerations. In higher orders the results depend on details of infrared cutoff. Another point of our interest is an alternative way of the anomaly matching through introduction of effective scalar fields arising in the hydrodynamic approximation

Metastable bound state of a pair of two-dimensional spatially separated electrons in anti-parallel magnetic fields

We propose a new mechanism for binding of two equally charged carriers in a double-layer system subjected by a magnetic field of a special form. A field configuration for which the magnetic fields in adjacent layers are equal in magnitude and opposite in direction is considered. In such a field an additional integral of motion - the momentum of the pair P arises. For the case when in one layer the carrier is in the zero (n=0) Landau level while in the other layer - in the first (n=1) Landau level the dependence of the energy of the pair on its momentum E(P} is found. This dependence turns out to be nonmonotonic one : a local maximum and a local minimum appears, indicating the emergence of a metastable bound state of two carrier with the same sign of electrical charge.Comment: 7 page

Trapping atoms on a transparent permanent-magnet atom chip

We describe experiments on trapping of atoms in microscopic magneto-optical traps on an optically transparent permanent-magnet atom chip. The chip is made of magnetically hard ferrite-garnet material deposited on a dielectric substrate. The confining magnetic fields are produced by miniature magnetized patterns recorded in the film by magneto-optical techniques. We trap Rb atoms on these structures by applying three crossed pairs of counter-propagating laser beams in the conventional magneto-optical trapping (MOT) geometry. We demonstrate the flexibility of the concept in creation and in-situ modification of the trapping geometries through several experiments.Comment: Modifications: A) Reference I. Barb et al., Eur. Phys. JD, 35, 75 (2005) added. B)Sentence rewritten: We routinely capture more than 10^6 atoms in a micro-MOT on a magnetized pattern. C) The magnetic field strengths are now given in Teslas. D) The second sentence in the fourth paragraph has been rewritten in order to more clearly describe the geometry and purpose of the compensation coils.E) In the seventh paragraph we have rewritten the sentence about the creation of the external magnetic field for the magnetic-domain patterning. F) In the ninth paragraph, we clarify the way to shift the trap center. G) Caption of Fig. 4 changed. H) We have modified paragraph 12 to improve the description on the guiding of the trap center along a toroidal pattern. I) The last two sentences of the manuscript have been rewritte

Splitting and merging an elongated Bose-Einstein condensate at finite temperature

We analyze coherence effects during the splitting of a quasi one-dimensional condensate into two spatially separated ones and their subsequent merging into a single condensate. Our analysis takes into account finite-temperature effects, where phase fluctuations play an important role. We show that, at zero-temperature, the two split condensates can be merged into a single one with a negligible phase difference. By increasing temperature to a finite value below the critical point for condensation ($T_c$), i.e., $0 \le T/T_c < 1$, a considerable enhancement of phase and density fluctuations appears during the process of splitting and merging. Our results show that if the process of splitting and merging is sufficiently adiabatic, the whole process is quite insensitive to phase fluctuations and even at high temperatures, a single condensate can be produced.Comment: 8 pages, 6 figure

АНАЛІЗ НЕСПРИЯТЛИВИХ ПОДІЙ ПІСЛЯ ІМУНІЗАЦІЇ ВАКЦИНАМИ ПРОТИ SARS CoV-2

Although the WHO-recommended coronavirus vaccines are safe and effective, vaccines provide new information to healthcare professionals about the extent and nature of adverse reactions to these drugs. The aim of the study is supplementing the available data on adverse reactions of vaccines on the example of the experience of vaccination of the teaching staff of the Cherkasy Medical Academy with vaccines COVISHIELD and COMIRNATY. Information for this study was collected retrospectively through a survey of 72 employees of the Cherkasy Medical Academy who were vaccinated with the COVISHIELD vaccine (first dose); 67 workers vaccinated with AstraZeneca (second dose); 54 workers who were vaccinated with COMIRNATY vaccine (first dose); 52 people vaccinated with this vaccine (second dose). The study confirmed that among the local side effects, the most common were pain at the injection site, among the systemic - fever, weakness, fatigue and drowsiness, headache, muscle pain, chills. Most of the side effects were most pronounced in young people, more often in women than in men.Although the WHO-recommended coronavirus vaccines are safe and effective, vaccines provide new information to healthcare professionals about the extent and nature of adverse reactions to these drugs. The aim of the study is supplementing the available data on adverse reactions of vaccines on the example of the experience of vaccination of the teaching staff of the Cherkasy Medical Academy with vaccines COVISHIELD and COMIRNATY. Information for this study was collected retrospectively through a survey of 72 employees of the Cherkasy Medical Academy who were vaccinated with the COVISHIELD vaccine (first dose); 67 workers vaccinated with AstraZeneca (second dose); 54 workers who were vaccinated with COMIRNATY vaccine (first dose); 52 people vaccinated with this vaccine (second dose). The study confirmed that among the local side effects, the most common were pain at the injection site, among the systemic - fever, weakness, fatigue and drowsiness, headache, muscle pain, chills. Most of the side effects were most pronounced in young people, more often in women than in men

Luttinger Liquid in the Core of Screw Dislocation in Helium-4

On the basis of first-principle Monte Carlo simulations we find that the screw dislocation along the hexagonal axis of an hcp He4 crystal features a superfluid core. This is the first example of a regular quasi-one-dimensional supersolid, and one of the cleanest cases of a regular Luttinger-liquid system. In contrast, the same type of screw dislocation in solid Hydrogen is insulating.Comment: replaced with revised versio

Estimation of probiotic and vitamine d efficiency in prophylactics of infectious diseases in premature infants

The objective: to study the efficacy of probiotic and vitamin D use in prophylaxis of infectious diseases in premature infants. Materials and methods. The reseach has been conducted on the base of the Odessa National Medical University – neonatal unit of the maternity hospital N 7 (Odessa). The I group consisted of 20 premature infants (PI) who got BioGiy drops. The II group conssted of 19 PI, who got BioGiy drops and vitamin D3. Control group- 23 PI who did not get the preparations mentioned above. At birth and at the age of 3–4 months complex immunological investigation was carried out. Every month the morbidity of PI was observed. Results. PI are more likely to suffer from infectious diseases, functional disorders of the gastrointestinal tract and hypovitaminosis D. The results obtained indicate a high effectiveness of probiotic with vitamin D3 use for the prevention of infectious diseases in PI. The greatest effect was observed in the prevention of skin infections and respiratory diseases of the upper respiratory tract as a reduction of respiratory episodes frequency, acceleration of recovery and lighter course of the disease. Also, the combination of probiotic and vitamin D has proven itself as a means of preventing hypovitaminosis D in PI

Effect of spatial resolution on the estimates of the coherence length of excitons in quantum wells

We evaluate the effect of diffraction-limited resolution of the optical system on the estimates of the coherence length of 2D excitons deduced from the interferometric study of the exciton emission. The results are applied for refining our earlier estimates of the coherence length of a cold gas of indirect excitons in coupled quantum wells [S. Yang et al., Phys. Rev. Lett. 97, 187402(2006)]. We show that the apparent coherence length is well approximated by the quadratic sum of the actual exciton coherence length and the diffraction correction given by the conventional Abbe limit divided by 3.14. In practice, accounting for diffraction is necessary only when the coherence length is smaller than about one wavelength. The earlier conclusions regarding the strong enhancement of the exciton coherence length at low temperatures remain intact.Comment: 6 pages, 5 figure