Density response of a trapped Fermi gas: a crossover from the pair vibration mode to the Goldstone mode

We consider the density response of a trapped two-component Fermi gas. Combining the Bogoliubov-deGennes method with the random phase approximation allows the study of both collective and single particle excitations. Calculating the density response across a wide range of interactions, we observe a crossover from a weakly interacting pair vibration mode to a strongly interacting Goldstone mode. The crossover is associated with a depressed collective mode frequency and an increased damping rate, in agreement with density response experiments performed in strongly interacting atomic gases.Comment: 14 pages, 8 figure

Thermal conductivity of solid parahydrogen with methane admixtures

The thermal conductivity of solid parahydrogen crystal with methane admixtures has been measured in the temperature range 1.5 to 8 K. Solid samples were grown from the gas mixture at 13 K. Concentration of CH₄ admixture molecules in the gas varied from 5 to 570 ppm. A very broad maximum of thermal conductivity with absolute value of about 110 W/(m×K) is observed at 2.6 K. The data are interpreted by Callaway model considering phonons resonant scattering on quasi-local vibrations of CH₄ molecules, phonon-grain boundary and phonon-phonon scattering processes. The increase of grain boundary scattering leads to the decrease of the maximum broadening. The analysis shows that the solid mixture of p-H₂ and CH₄ is a heterogeneous solution for CH₄ concentration higher than 0.1 ppm

Asymptotic Expansions for Stationary Distributions of Perturbed Semi-Markov Processes

New algorithms for computing of asymptotic expansions for stationary distributions of nonlinearly perturbed semi-Markov processes are presented. The algorithms are based on special techniques of sequential phase space reduction, which can be applied to processes with asymptotically coupled and uncoupled finite phase spaces.Comment: 83 page

Collision of one dimensional (1D) spin polarized Fermi gases in an optical lattice

In this work we analyze the dynamical behavior of the collision between two clouds of fermionic atoms with opposite spin polarization. By means of the time-evolving block decimation (TEBD) numerical method, we simulate the collision of two one-dimensional clouds in a lattice. There is a symmetry in the collision behaviour between the attractive and repulsive interactions. We analyze the pair formation dynamics in the collision region, providing a quantitative analysis of the pair formation mechanism in terms of a simple two-site model

Клиническое исследование переносимости, безопасности и иммуногенности отечественной гриппозной инактивированной сплит-вакцины «ФЛЮ-М» у детей в возрасте от 6 месяцев до 9 лет

Purpose: To study the reactogenicity, safety and immunogenicity of the Russian vaccine Flu-M in comparison with Vaxigrip vaccine for influenza prevention in children aged from 6 months to 9 years (phase III).Materials and Methods. In 2021, a clinical study was conducted in which children aged 6 months to 9 years were immunized with Flu-M vaccine (produced by SPbSRIVS, Russia) and Vaxigrip vaccine (produced by Sanofi Pasteur S.A., France). After randomization one group of children was vaccinated with Flu-M, the other with Vaxigrip, and monitored for 180±3 days after vaccination. Children vaccinated between 3 and 9 years of age were studied in phase I, and between 6 months and 3 years of age in phase II. Tolerability and safety were assessed by the frequency and extent of adverse events, as well as by the assessment of vital signs and physical examination. Immunological efficacy assessment criteria were geometric mean antibody titer, seroconversion level, seroconversion factor, seroprotection level.Results. Both vaccines (Flu-M and Vaxigrip) were shown to be well tolerated by children of both age groups. No serious adverse events or severe adverse events were reported   in the study. Immunological efficacy criteria were achieved for both vaccines for all strains of influenza virus in children of both age groups at 28 and 56 days after vaccination. No cases of influenza or acute respiratory infections were seen at 180±3 days postvaccination.Conclusion. The results of the clinical study show that the Flu-M and Vaxigrip vaccines are comparable in both age groups of children.The trial is registered at ClinicalTrials.gov (NCT 05470582).Цель: изучение реактогенности, безопасности и иммуногенности отечественной вакцины «Флю-М» в сравнении с вакциной «Ваксигрип» для профилактики гриппа у детей в возрасте от 6 месяцев до 9 лет (фаза III).Материалы и методы: в 2021 г. проведено клиническое исследование при иммунизации детей в возрасте от 6 месяцев до 9 лет вакциной «Флю-М» (производство СПбНИИВС, Россия) и вакциной «Ваксигрип» (производство «Санофи Пастер С.А.», Франция). После рандомизации в соотношении 1:1 одну группу детей прививали вакциной «Флю-М», другую  –  вакциной  «Ваксигрип» и наблюдали в течение 180±3 суток после  вакцинации. На I этапе исследовали детей в возрасте от 3 до    9 лет, на II этапе – в возрасте от 6 месяцев до 3 лет. Переносимость и безопасность оценивали по частоте развития и степени тяжести нежелательных явлений, а также по результатам лабораторных исследований, оценки показателей жизненно важных функций и результатам физикального обследования и неврологического осмотра. Критериями оценки иммунологической эффективности являлись средняя геометрическая титра антител, уровень сероконверсии, фактор сероконверсии, уровень серопротекции.Результаты: показано, что обе вакцины («Флю-М» и «Ваксигрип») хорошо переносились детьми обеих возрастных групп. Нежелательных явлений сильной степени тяжести, а также серьезных нежелательных явлений в исследовании не было зарегистрировано. Критерии иммунологической эффективности были достигнуты для обеих вакцин по всем штаммам вируса гриппа у детей обеих возрастных категорий через 28 и 56 дней после вакцинации. В ходе наблюдения в течение 180±3 суток после вакцинации случаев заболеваемости гриппом или острыми респираторными вирусными инфекциями не отмечалось.Заключение: результаты клинического исследования свидетельствуют о сопоставимости вакцин «Флю-М» и «Ваксигрип» для детей обеих возрастных категорий. Исследование зарегистрировано на ClinicalTrials.gov (NCT05470582)