Reflection principle characterizing groups in which unconditionally closed sets are algebraic

We give a necessary and sufficient condition, in terms of a certain reflection principle, for every unconditionally closed subset of a group G to be algebraic. As a corollary, we prove that this is always the case when G is a direct product of an Abelian group with a direct product (sometimes also called a direct sum) of a family of countable groups. This is the widest class of groups known to date where the answer to the 63 years old problem of Markov turns out to be positive. We also prove that whether every unconditionally closed subset of G is algebraic or not is completely determined by countable subgroups of G.Comment: 14 page

Residual Welding Stresses Control by Sphere Indentor Penetration

The report describes the technique of the residual welding stresses control on the basis of the sphere indentor penetration into the flat surface of a welded joint succeeded by the stress-strain state registration by the hologram interferometry.В докладе приведена методика контроля остаточных сварочных напряжений на основе вдавливания в плоскую поверхность сварного соединения шарового индентора с последующей регистрацией напряженно-деформированного состояния методом голографической интерферометрии

Development of Residual Welding Stresses Control by Groove FformingTechnique

The report describes the technique of the residual welding stresses control on the basis of shallow long length groove forming on the surface of a welded jointsucceeded bythe stress-strain state registration by the hologram interferometry.В докладе приведена методика контроля остаточных сварочных напряжений на основе создания на поверхности сварного соединения неглубокой протяженной канавки с последующей регистрацией измененного напряженно-деформированного состояния методом голографической интерферометрии

Accidental hypothermia as a factor of microcirculatory disorders

Aim. To study the dynamics of indicators of microcirculation during a single episode of hypothermia of moderate degree in rats, both immediately after cessation of cooling, and in different periods of posthypothermia. Methods. The study was performed on 25 Wistar rats. The animals were subjected to a single immersion cooling in water at a temperature of 5 °C until reaching a rectal temperature of 27-30 °C. Analysis of the microvasculature was carried out immediately upon reaching a moderate degree of hypothermia, 2, 5, 10 and 14 days after the cooling. The microcirculation parameters were estimated using a laser analyzer of capillary circulation LAKK-02 (SMO «Lazma», Russia) at a wavelength of 0.63 μm. The main parameters of microcirculation were recorded, and the amplitude-frequency spectrum of blood flow oscillations was analyzed. Results. Immediately after reaching a moderate degree of hypothermia, vasospasm was recorded, which was confirmed by a decrease in the rate of perfusion and wave amplitudes of all frequency ranges. 2 days after stopping the cooling perfusion index returned to baseline, a decrease in amplitude of endothelial, vasomotor and respiratory waves was observed with an increase in pulse waves. On day 5, perfusion increased by 5 times was observed along with decreased amplitudes of the waves of all ranges. By day 10, the level of blood flow returned to its original values, and the wave amplitudes of all frequency ranges remained at the same low level. By day 14, a progressive decrease of the factors of bloodflow modulation was associated by the decrease of perfusion. Conclusion. Single cooling to a moderate degree of hypothermia leads to a progressive decrease of tissue perfusion and deep inhibition of active and passive factors of bloodflow modulation

Distress symptoms development after a single episode of ultrasound exposure

Aim. To study the influence of a single 24-hour episode of exposure to ultrasound waves propagating in air on microcirculation and parameters of hemostasis in rats. Methods. The study was performed on 28 Wistar male rats. The experimental group was exposed to ultrasound for 24 hours. Geometric mean frequency was 25 kHz, acoustic pressure was 84.3 dB. Parameters of microcirculation of experimental rats received by laser Doppler flowmetry were compared with those of intact animals. Also comparative analysis of platelet and coagulation hemostasis, anticoagulant and fibrinolytic plasma activity was performed in rats from both groups. Results. In experimental rats in response to 24-hour exposure to ultrasound, significant decrease of the studied active and passive factors of blood flow modulation occurred compared to those of intact animals: parameters of microcirculation, flax, endothelial and vasomotor wave amplitude, respiratory and pulse wave amplitude. When studying the parameters of hemostasis, significant hypercoagulation of extrinsic pathway and at the latest stages of coagulation which worsened with anticoagulant plasma activity inhibition along with decrease of fibrinolytic activity. The character of changes of hemostatic parameters confirmed the development of stress-reaction in rats registered during the study of microcirculation. Conclusion. 24-hour ultrasound exposure causes significant disorders of microcirculation and unfavorable shifts in hemostasis - the signs of distress

Morphological determinants for the local hemostatic effect of exogenous fibrin monomer in its systemic administration after injury with inhibition of platelet aggregation in the experiment

Background. In our previously published studies, we demonstrated a high hemostatic activity of a low dose of exogenous fibrin monomer during its systemic administration in a model of dosed liver injury with preliminary inhibition of platelet aggregation. However, the analysis of platelet involvement in the mechanisms of local fibrin formation has not been analyzed. The aim of the study. To conduct a comparative analysis of the cellular composition of venous and wound blood, as well as blood in the wound vessels to assess the contribution of platelets to the hemostatic effect of exogenously administered fibrin monomers in dosed liver injury under conditions of pharmacologically determined thrombocytopathy. Methods. In a model of dosed liver injury in rabbits after inhibition of platelet aggregation by  acetylsalicylic acid in combination with clopidogrel, the effect of the administration of fibrin monomer was evaluated in comparison with the use of tranexamic acid. We studied the number of platelets in venous and wound blood smears, as well as in the contents of wound vessels. Results. It has been established that with the systemic administration of exogenous fibrin monomer, the number of platelets in wound blood smears decreases by 17.2 % in comparison with free circulating venous blood. Platelets in wound blood form aggregates and are in an activated state. In the wound vessels, the number of these cells was maximum (150 per lower field) compared with the number of platelets in the placebo and tranexamic acid groups (55 and 84 per lower field, respectively). Also in the wound blood, erythrocytes with altered forms (echinocytes, schistocytes, stomatocytes and ovalocytes) were found. Conclusion. Systemic administration of exogenous fibrin monomer affects the redistribution of platelets between the systemic circulation, wound vessels and wound blood, determining its hemostatic effect and local wound fibrin formation in dosed liver injury. The presence of receptor-mediated platelets recruitment due to fibrin monomer in the wound vessels with the  participation of damaged erythrocytes is assumed

Time-dependent systemic hemostatic effects of fibrin monomer in controlled liver injury in the experiment

Aim. To evaluate the hemostatic effect of fibrin monomer after its intravenous administration at different time periods in experimental trauma. Methods. In the experiments, in a placebo-controlled study, hemostatic and hemostasiological effects of systemic use of fibrin monomer were studied at different time periods after its administration (in 5 min, 1 h and 3 h) in 97 male rabbits of the Chinchilla breed in the controlled liver injury model. Results. A pronounced hemostatic effect was demonstrated for fibrin monomer used at a dose of 0.25 mg/kg demonstrated by a 6.3-fold decrease of blood loss volume (% of circulating blood volume) compared to placebo on the background of the intravenous preventive fibrin monomer administration 1 hour prior to controlled liver injury. Fibrin monomer administration at a stated dose was not accompanied by significant changes in haemocoagulative parameters including measurement of platelet count, activated partial thromboplastin time, prothrombin time, thrombin time, echitox time, fibrinogen concentration, level of soluble fibrin monomer complexes, D-dimer content, and antithrombin III activity. The effect of fibrin monomer is probably realized through some effectors, the nature of which has not yet been studied. The obtained results allow choosing the optimal interval between intravenous administrations of fibrin monomer and controlled liver injury for further study of the mechanisms of its hemostatic action. Conclusion. Fibrin monomer in small doses (0.25 mg/kg) is able to exert a pronounced hemostatic effect with its systemic administration 1 hour prior to the injury without significant changes in haemocoagulative parameters

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised