Second virial coefficients of light nuclear clusters and their chemical freeze-out in nuclear collisions

Here we develop a new strategy to analyze the chemical freeze-out of light (anti)nuclei produced in high energy collisions of heavy atomic nuclei within an advanced version of the hadron resonance gas model. It is based on two different, but complementary approaches to model the hard-core repulsion between the light nuclei and hadrons. The first approach is based on an approximate treatment of the equivalent hard-core radius of a roomy nuclear cluster and pions, while the second approach is rigorously derived here using a self-consistent treatment of classical excluded volumes of light (anti)nuclei and hadrons. By construction, in a hadronic medium dominated by pions, both approaches should give the same results. Employing this strategy to the analysis of hadronic and light (anti)nuclei multiplicities measured by ALICE at $\sqrt{s_{NN}} =2.76$ TeV and by STAR at $\sqrt{s_{NN}} =200$ GeV, we got rid of the existing ambiguity in the description of light (anti)nuclei data and determined the chemical freeze-out parameters of nuclei with high accuracy and confidence. At ALICE energy the nuclei are frozen prior to the hadrons at the temperature $T = 175.1^{+2.3}_{-3.9}$ MeV, while at STAR energy there is a single freeze-out of hadrons and nuclei at the temperature $T = 167.2 \pm 3.9$ MeV. We argue that the found chemical freeze-out volumes of nuclei can be considered as the volumes of quark-gluon bags that produce the nuclei at the moment of hadronization.Comment: 15 pages, 4 figures, 3 table

Особенности течения и частота ремиссии атопической бронхиальной астмы у взрослых пациентов в Челябинске

Data on asthma remission in adults are scarce worldwide and have not been searched in Russian Federation.The aim of the study was to describe clinical course and remission rate in adult patients with atopic asthma in Chelyabinsk.Methods. A retrospective analysis of 313 outpatient records of patients with atopic asthma aged 18 to 70 years was carried out. The patients were followed from 1992 to 2018. The median duration of the follow-up was 8 (5; 15) years. Then, the patients were surveyed by phone. Asthma Control Test (AСT) was used in 181 (58%) of 313 respondents. Clinical remission of asthma was determined as being symptom-free with no need in inhaled corticosteroids (ICSs) and short-acting β2-agonists (SABAs) during ≥ 1 year.Results. The median age of asthma onset was 14.5 (8; 2) years in males and 28 (24; 36) years in females (p < 0.001). The diagnosis was made 5 years after the onset of symptoms. Asthma severity was related to gender: mild asthma was seen more often in males compared to females (p = 0.008). Allergic rhinitis and asthma comorbidity was found in 78% of patients. The proportion of patients sensitized to pollen was 72%; tree pollen allergens were the main cause of seasonal allergy (in 51% of patients). Different combinations of sensitization to indoor, animal, and pollen allergens (polysensitization) were detected in 80% of patients. Clinical remission of atopic bronchial asthma was determined in 22.7% of cases. Asthma remission was not related to the patient’s gender or age of symptom onset. The median age of the remission group patients was 33 (28; 39.5) years vs 40 (29; 51) years in patients without remission (p = 0.015). Asthma remission was associated with normal body mass index (23 (21; 24) kg / m2 vs 25 (22; 29) kg / m2 (p = 0.007); allergen elimination (p < 0.001) and allergen-specific immunotherapy (p < 0.001).Conclusion. Predicting the probability of asthma remission and identifying conditions required to achieve the remission could improve our knowledge about asthma natural course and could increase treatment efficacy and adherence of patients to the treatment. Данные о ремиссии бронхиальной астмы (БА) у взрослых в мире ограничены, а в Российской Федерации не представлены. В отечественной литературе отсутствует информация о частоте, временных критериях и факторах, способствующих наступлению этого периода заболевания.Целью исследования явилось определение особенностей течения и частоты ремиссии у взрослых пациентов с атопической БА (АБА) в Челябинске.Материалы и методы. Проведен ретроспективный анализ амбулаторных карт пациентов (n = 313; возраст – 18–70 лет) с АБА. Наблюдение проводилось в 1992–2018 гг. Медиана продолжительности наблюдения составила 8 [5; 15] лет. Второй этап включал телефонное анкетирование и проведение теста по контролю над БА (Asthma Control Test – АСТ) 181 (58 %) больного. Клиническая ремиссия БА продолжительностью ≥ 1 года определялась при отсутствии симптомов без применения ингаляционных глюкокортикостероидов и короткодействующих β2-агонистов.Результаты. Медиана возраста начала АБА у мужчин составила 14,5 [8; 22] года, у женщин – 28 [24; 36] лет (р < 0,001). Установлена 5-летняя разница между возрастом начала симптомов БА (22 года) и возрастом постановки диагноза (27 лет). Выявлено, что степень тяжести БА зависит от пола – у мужчин чаще отмечается легкое течение по сравнению с женщинами (р = 0,008). Сочетание аллергического ринита с БА отмечено в 78 % случаев. Доля лиц с пыльцевой аллергией составила 72 %. В развитии сезонной аллергии основными значимыми причинами (51 %) стали аллергены пыльцы деревьев. Различные варианты сочетания реакции к бытовым, эпидермальным и пыльцевым аллергенам (полисенсибилизация) выявлены у 80 % пациентов. Клиническая ремиссия у взрослых лиц с АБА определена в 22,7 % случаев, зависимость от пола пациента и возраста начала симптомов заболевания не выявлена. Медиана возраста в группе ремиссии была на 7 лет меньше и составила 33 [28; 39,5] года vs 40 [29; 51] лет (р = 0,015). Определены факторы, ассоциированные с ремиссией, – нормальное значение индекса массы тела (23 [21; 24] кг / м2 vs 25 [22; 29] кг / м2 ; р = 0,007), проведение элиминационных мероприятий (р < 0,001) и аллерген-специфической иммунотерапии (р < 0,001).Заключение. Прогноз вероятности ремиссии БА и знание условий, при которых она развивается, значительно дополнит представление о БА, повысит не только уверенность врачей в успехе терапии, но и приверженность пациентов предложенному лечению.

Induced surface and curvature tension equation of state for hadron resonance gas in finite volumes and its relation to morphological thermodynamics

Here we develop an original approach to investigate the grand canonical partition function of the multicomponent mixtures of Boltzmann particles with hard-core interaction in finite and even small systems of the volumes above 20 fm$^3$. The derived expressions of the induced surface tension equation of state are analyzed in details. It is shown that the metastable states, which can emerge in the finite systems with realistic interaction, appear at very high pressures at which the hadron resonance gas, most probably, is not applicable at all. It is shown how and under what conditions the obtained results for finite systems can be generalized to include into a formalism the equation for curvature tension. The applicability range of the obtained equations of induced surface and curvature tensions for finite systems is discussed and their close relations to the equations of the morphological thermodynamics are established. The hadron resonance gas model on the basis of the obtained advanced equation of state is worked out. Also, this model is applied to analyze the chemical freeze-out of hadrons and light nuclei with the number of (anti-)baryons not exceeding 4, including the most problematic ratios of hyper-triton and its antiparticle. Their multiplicities were measured by the ALICE Collaboration in the central lead-lead collisions at the center-of-mass energy $\sqrt{s_{\rm NN}} =$ 2.76 TeV.Comment: 24 pages, 3 figures and 1 tabl

Серопревалентность сотрудников первичного звена здравоохранения Санкт-Петербурга в период эпидемического неблагополучия по кори

The measles situation is still unstable — there are imported cases, the formation of nosocomial foci with the involvement of medical personnel, patients and visitors of medical institutions.Objective of the study: to assess the level of seroprevalence of primary health care workers in St. Petersburg during the period of epidemic trouble with measles.Materials and methods: An open retrospective randomized uncontrolled study of the intensity of specific immunity to measles in 980 employees aged 18 to 78 years, examined in July-September 2018, was carried out. The level of anti-measles IgG antibodies was determined by the method of enzyme-linked immunosorbent assay (810 people) and passive hemagglutination reactions (170 people). The results are presented with the indication of the shares (%) and the calculation of the 95% confidence interval according to Clopper — Pearson. Differences between groups were assessed using Pearson's chi-square test (%2). Differences in the groups were considered statistically significant when the criterion level was p < 0.05.Results: It was found that 8.2% of personnel are not protected against measles infection. At the same time, the number of seronegative persons among doctors (8.1 %), nurses (7.7%) and non-medical workers (9.6%) differed statistically. Age-related differences in the immune layer were revealed — the greatest susceptibility was observed in persons under 30 years of age (1 8.3%). Anti-measles antibodies in those who had been ill persisted for a long time and at a high level. At the same time, the intensity of post-vaccination immunity decreased over time, and 20 years after immunization, the number of seronegative individuals increased significantly. Only 64.1 % of those surveyed had two vaccinations, more than a third were immunized once. Nevertheless, the proportion of people unprotected from measles exceeded the criterion of epidemic well-being with the same frequency in both groups (9.2% and 1 0.4%, respectively).The results of a serological study showed that the presence of a record of two vaccinations in the certificate in 9.2% of cases does not guarantee protection in case of contact with a patient with measles. Only a serological examination is evidence of specific immunity to measles infection.Ситуация по кори до настоящего времени остается нестабильной — отмечаются завозные случаи, формирование внутрибольничных очагов с вовлечением медицинского персонала, пациентов и посетителей лечебных учреждений.Цель исследования: оценить уровень серопревалентности сотрудников первичного звена здравоохранения Санкт-Петербурга в период эпидемического неблагополучия по кори.Материалы и методы: Проведено открытое ретроспективное рандомизированное неконтролируемое исследование напряженности специфического иммунитета к кори у 980 сотрудников в возрасте от 18 до 78 лет, обследованных в июле-сентябре 2018 г. Уровень противокоревых антител класса IgG определялся методом иммуноферментного анализа (810 чел.) и реакции пассивной гемагглютинации (170 чел.). Результаты представлены с указанием долей (%) и расчетом 95% доверительного интервала по Клопперу-Пирсону. Различия между группами оценивали с помощью критерия %2 Пирсона. Различия в группах считались статистически значимыми при уровне критерия p < 0,05.Результаты: Установлено, что 8,2% персонала не защищены против коревой инфекции. При этом количество серонегативных лиц среди врачей (8,1%), среднего медицинского персонала (7,7%) и немедицинских работников (9,6%) статистически не различалось. Выявлены возрастные различия в иммунной прослойке — наибольшая восприимчивость отмечена у лиц моложе 30 лет (18,3%). Противокоревые антитела у переболевших сохранялись длительно и на высоком уровне. В то же время напряженность поствакцинального иммунитета с течением времени снижалась и через 20 лет после иммунизации значительно возросло количество серонегативных лиц. Две прививки имели только 64,1 % обследованных, более трети оказались иммунизированы однократно. Тем не менее доля незащищенных от кори лиц превышала критерий эпидемического благополучия с одинаковой частотой в обеих группах (9,2% и 1 0,4% соответственно).Результаты серологического исследования показали, что наличие в сертификате записи о двух прививках в 9,2% случаях не гарантирует защиту при контакте с больным корью. Только серологическое обследование является доказательством наличия специфического иммунитета к коревой инфекции

Measurement of global polarization of {\Lambda} hyperons in few-GeV heavy-ion collisions

The global polarization of {\Lambda} hyperons along the total orbital angular momentum of a relativistic heavy-ion collision is presented based on the high statistics data samples collected in Au+Au collisions at \sqrt{s_{NN}} = 2.4 GeV and Ag+Ag at 2.55 GeV with the High-Acceptance Di-Electron Spectrometer (HADES) at GSI, Darmstadt. This is the first measurement below the strangeness production threshold in nucleon-nucleon collisions. Results are reported as a function of the collision centrality as well as a function of the hyperon transverse momentum (p_T) and rapidity (y_{CM}) for the range of centrality 0--40%. We observe a strong centrality dependence of the polarization with an increasing signal towards peripheral collisions. For mid-central (20--40%) collisions the polarization magnitudes are (%) = 6.0 \pm 1.3 (stat.) \pm 2.0 (syst.) for Au+Au and (%) = 4.6 \pm 0.4 (stat.) \pm 0.5 (syst.) for Ag+Ag, which are the largest values observed so far. This observation thus provides a continuation of the increasing trend previously observed by STAR and contrasts expectations from recent theoretical calculations predicting a maximum in the region of collision energies about 3 GeV. The observed polarization is of a similar magnitude as predicted by 3D fluid dynamics and the UrQMD plus thermal vorticity model and significantly above results from the AMPT model.Comment: 8 pages, 4 figure

Production of {\pi}+ and K+ mesons in argon-nucleus interactions at 3.2 AGeV

First physics results of the BM@N experiment at the Nuclotron/NICA complex are presented on {\pi}+ and K+ meson production in interactions of an argon beam with fixed targets of C, Al, Cu, Sn and Pb at 3.2 AGeV. Transverse momentum distributions, rapidity spectra and multiplicities of {\pi}+ and K+ mesons are measured. The results are compared with predictions of theoretical models and with other measurements at lower energies.Comment: 29 pages, 20 figure

Inclusive e+^+e−^- production in collisions of pions with protons and nuclei in the second resonance region of baryons

Inclusive e$^+$e$^-$ production has been studied with HADES in $\pi^-$ + p, $\pi^-$ + C and $\pi^- + \mathrm{CH}_2$ reactions, using the GSI pion beam at $\sqrt{s_{\pi p}}$ = 1.49 GeV. Invariant mass and transverse momentum distributions have been measured and reveal contributions from Dalitz decays of $\pi^0$, $\eta$ mesons and baryon resonances. The transverse momentum distributions are very sensitive to the underlying kinematics of the various processes. The baryon contribution exhibits a deviation up to a factor seven from the QED reference expected for the dielectron decay of a hypothetical point-like baryon with the production cross section constrained from the inverse $\gamma$ n$\rightarrow \pi^-$ p reaction. The enhancement is attributed to a strong four-momentum squared dependence of the time-like electromagnetic transition form factors as suggested by Vector Meson Dominance (VMD). Two versions of the VMD, that differ in the photon-baryon coupling, have been applied in simulations and compared to data. VMD1 (or two-component VMD) assumes a coupling via the $\rho$ meson and a direct coupling of the photon, while in VMD2 (or strict VMD) the coupling is only mediated via the $\rho$ meson. The VMD2 model, frequently used in transport calculations for dilepton decays, is found to overestimate the measured dielectron yields, while a good description of the data can be obtained with the VMD1 model assuming no phase difference between the two amplitudes. Similar descriptions have also been obtained using a time-like baryon transition form factor model where the pion cloud plays the major role.Comment: (HADES collaboration

Seroprevalence of primary health care workers in Saint-Petersburg during a measles epidemic

The measles situation is still unstable — there are imported cases, the formation of nosocomial foci with the involvement of medical personnel, patients and visitors of medical institutions.Objective of the study: to assess the level of seroprevalence of primary health care workers in St. Petersburg during the period of epidemic trouble with measles.Materials and methods: An open retrospective randomized uncontrolled study of the intensity of specific immunity to measles in 980 employees aged 18 to 78 years, examined in July-September 2018, was carried out. The level of anti-measles IgG antibodies was determined by the method of enzyme-linked immunosorbent assay (810 people) and passive hemagglutination reactions (170 people). The results are presented with the indication of the shares (%) and the calculation of the 95% confidence interval according to Clopper — Pearson. Differences between groups were assessed using Pearson's chi-square test (%2). Differences in the groups were considered statistically significant when the criterion level was p < 0.05.Results: It was found that 8.2% of personnel are not protected against measles infection. At the same time, the number of seronegative persons among doctors (8.1 %), nurses (7.7%) and non-medical workers (9.6%) differed statistically. Age-related differences in the immune layer were revealed — the greatest susceptibility was observed in persons under 30 years of age (1 8.3%). Anti-measles antibodies in those who had been ill persisted for a long time and at a high level. At the same time, the intensity of post-vaccination immunity decreased over time, and 20 years after immunization, the number of seronegative individuals increased significantly. Only 64.1 % of those surveyed had two vaccinations, more than a third were immunized once. Nevertheless, the proportion of people unprotected from measles exceeded the criterion of epidemic well-being with the same frequency in both groups (9.2% and 1 0.4%, respectively).The results of a serological study showed that the presence of a record of two vaccinations in the certificate in 9.2% of cases does not guarantee protection in case of contact with a patient with measles. Only a serological examination is evidence of specific immunity to measles infection