636 research outputs found

    Third and fourth degree collisional moments for inelastic Maxwell models

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    The third and fourth degree collisional moments for dd-dimensional inelastic Maxwell models are exactly evaluated in terms of the velocity moments, with explicit expressions for the associated eigenvalues and cross coefficients as functions of the coefficient of normal restitution. The results are applied to the analysis of the time evolution of the moments (scaled with the thermal speed) in the free cooling problem. It is observed that the characteristic relaxation time toward the homogeneous cooling state decreases as the anisotropy of the corresponding moment increases. In particular, in contrast to what happens in the one-dimensional case, all the anisotropic moments of degree equal to or less than four vanish in the homogeneous cooling state for d2d\geq 2.Comment: 15 pages, 3 figures; v2: addition of two new reference

    Non-Equilibrium Reaction Rates in the Macroscopic Chemistry Method for DSMC Calculations

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    The Direct Simulation Monte Carlo (DSMC) method is used to simulate the flow of rarefied gases. In the Macroscopic Chemistry Method (MCM) for DSMC, chemical reaction rates calculated from local macroscopic flow properties are enforced in each cell. Unlike the standard total collision energy (TCE) chemistry model for DSMC, the new method is not restricted to an Arrhenius form of the reaction rate coefficient, nor is it restricted to a collision cross-section which yields a simple power-law viscosity. For reaction rates of interest in aerospace applications, chemically reacting collisions are generally infrequent events and, as such, local equilibrium conditions are established before a significant number of chemical reactions occur. Hence, the reaction rates which have been used in MCM have been calculated from the reaction rate data which are expected to be correct only for conditions of thermal equilibrium. Here we consider artificially high reaction rates so that the fraction of reacting collisions is not small and propose a simple method of estimating the rates of chemical reactions which can be used in the Macroscopic Chemistry Method in both equilibrium and non-equilibrium conditions. Two tests are presented: (1) The dissociation rates under conditions of thermal non-equilibrium are determined from a zero-dimensional Monte-Carlo sampling procedure which simulates ‘intra-modal’ non-equilibrium; that is, equilibrium distributions in each of the translational, rotational and vibrational modes but with different temperatures for each mode; (2) The 2-D hypersonic flow of molecular oxygen over a vertical plate at Mach 30 is calculated. In both cases the new method produces results in close agreement with those given by the standard TCE model in the same highly nonequilibrium conditions. We conclude that the general method of estimating the non-equilibrium reaction rate is a simple means by which information contained within non-equilibrium distribution functions predicted by the DSMC method can be included in the Macroscopic Chemistry Method

    THE SPECIFIC FEATURES OF HEART AND VESSELS REMODELING IN PATIENTS WITH CHRONIC HEART FAILURE TREATED WITH LISINOPRIL DURING 6 MONTHS

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    Background. Being able to attenuate pathological remodeling, ACE inhibitors are considered to be first line medications for chronic heart failure (CHF) treatment.Aim. To study the influence of the 6-month combined therapy with lisinopril on the heart and vessels remodeling in patients with ischemic CHF.Material and Methods. 40 patients with CHF after Q-myocardial infarction were treated with lisinopril (Listril, Dr.Reddy’s, India) as a part of complex therapy. Initially and after 6 months of therapy the following findings were evaluated: the 6-minute walk test results, echocardiography parameters, main arteries rigidity, endothelium-dependent and independent vasodilatation, anticoagulant and fibrinolytic function of vascular endothelium, von Willebrand factor (VWF).Results. 6-month treatment with lisinopril showed reduction in CHF functional class in 30 % of patients and increase in left ventricle (LV) stroke volume by 3,8% and LV ejection fraction by 1%. Pulse-wave velocity reduced insignificantly from 10,2 to 9,2 m/sec and augmentation indices of aorta from 31,4% to 29,9% as well as this of brachial artery from -2,6% to -6%. Endothelium-dependent vasodilatation increased from 6,4% to 8,6% and independent vasodilatation – from 13,8% to 16,6%. VWF activity decrease was observed in 40% of CHF patients. Significant changes in anticoagulant and fibrinolytic function of vascular endothelium were not revealed.Conclusion. Lisinopril administration as a part of complex therapy of CHF patients during 6 months resulted in favorable effect on heart and vessels remodeling and was well tolerated

    High-frequency dielectric anomalies in a highly frustrated square kagome lattice nabokoite family compounds ACu7_7(TeO4_4)(SO4_4)5_5Cl (A=Na, K, Rb, Cs)

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    Nabokoite family compounds ACu7_7(TeO4_4)(SO4_4)5_5Cl (A=Na, K, Cs, Rb) are candidates for the experimental realization of highly-frustrated 2D square kagome lattice (SKL). Their magnetic subsystem includes SKL layers decorated by additional copper ions. All members of this family are characterized by quite high Curie-Weiss temperatures (80200\sim 80-200 K), but magnetic ordering was reported only for Na and K compounds at a much lower temperatures below 4 K. We report here results of the study of high-frequency (10\sim 10 GHz) dielectric properties of this family of compounds. Our study revealed presence of the strong dielectric anomaly both in the real and imaginary parts of high-frequency dielectric permittivity for Na and K compounds approx. 100 and 26 K, correspondingly, presumably related to antiferroelectric ordering. Additionally, much weaker anomalies were observed at approximately 5K indicating possible interplay of magnetic and lattice degrees of freedom. We discuss possible relation between the structure rearrangements accompanying dielectric anomalies and a delayed magnetic ordering in the nabokoite family compounds.Comment: 12 pages, 8 figure

    Reply to «Comments to the paper “Diagnosis of spondyloarthritis: Should we need new criteria?”» published in the journal «Sovremennaya Revmatologiya»

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    В первом номере журнала «Современная ревматология» за 2015 г. была опубликована статья И.З. Гайдуковой, А.И. Акуловой, А.В. Апаркиной, А.П. Реброва «Диагностика спондилоартрита: нужны ли нам новые критерии?». В ответ на публикацию статьи в третьем номере журнала вышли комментарии профессора Ш.Ф. Эрдеса

    CHANGES IN THE LEVELS OF ANGIOTENSIN II, ALDOSTERONE, AND FIBROBLAST GROWTH FACTOR IN PATIENTS WITH RHEUMATOID ARTHRITIS IN RELATION TO CLINICAL FEATURES

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    Angiotensin II, aldosterone, and fibroblast growth factor (FGF) stimulate neoangiogenesis, fibroblast proliferation, and elaboration of proinflammatory cytokines, which in turn contributes to increased pannus mass and the development of joint tissue destruction in rheumatoid arthritis (RA).Objective: to establish the specific features of changes in the blood levels of angiotensin II, aldosterone, and FGF in patients with RA in relation to the duration and severity of the disease.Subjects and methods. Examinations were made in 194 patients diagnosed with RA without comorbidity; the patients’ mean age was 47.7±10.2 years; the disease duration was 3.82±3.43 years. DAS28 scores for RA were calculated based on C-reactive protein levels. An enzyme immunoassay was used to determine the serum levels of anti-cyclic citrullinated peptide antibodies (ACCPA), angiotensin II, aldosterone, and FGF.Results and discussion. All the examinees were ascertained to have increases in the concentration of angiotensin II and aldosterone in blood by twice and in that of FGF by 2.5 times compared to the controls (p < 0.05). In patients with a RA duration of < 2 years, the blood level of angiotensin II was 25% higher than in those with a RA duration of > 5 years and the concentrations of aldosterone and FGF in patients with long-term RA were twice as high as in those with early RA. In patients with high RA activity, the blood level of angiotensin II was 1.5-fold higher than in those with low and moderate disease activity (p < 0.05). In patients with a high blood ACCPA level, the concentrations of angiotensin II, aldosterone, and FGF were 20, 30, and 25%, respectively, higher than in those with low ACCPA levels. The correlation of DAS28 with blood angiotensin II levels increased with enhanced RA activity. The high aldosterone and FGF values in RA patients are associated with the progression of joint radiographic changes

    The daily arterial stiffness profile in rheumatoid arthritis patients with and without hypertension

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    Patients with rheumatoid arthritis (RA) have an increased risk for cardiovascular diseases. To determine their daily arterial stiffness (AS) as an indicator of cardiovascular risk is of unquestionable interest.Objective: to evaluate the features of daily AS in RA patients with or without hypertension.Patients and methods. Twenty-four hour AS monitoring (24-h ASM) was done in 75 women with a valid diagnosis of RA. The patients were randomized into 3 groups: 1) 39 RA patients with hypertension; 2) 24 RA patients without hypertension; 3) 12 RA patients with masked hypertension. A comparison group consisted of 30 hypertensive patients without RA and a control group included 22 apparently healthy women who were age-matched with the patients with RA and those from the comparison group. 24-h ASM readings were studied using a BPlab device with Vasotens software (Russia).Results. All the patients with RA were found to have higher 24-h ASM readings than the controls; and, in the presence of hypertension, these changes were even more pronounced. Group 1 was noted to have higher ambulatory AS index than the comparison group; more than 70% of the patients in Group 2 were observed tohave increased aortic pulse wave velocity when reducing to a blood pressure (BP) of 100 mm Hg. The patients in Groups 1 and 2 had increases in augmentation index, in the latter normalized for a heart rate of 75 beats/min, in the propagation time of a reflected wave when reducing to a BP of 100 mm Hg, and in AS index at night. The patients with RA showed an association between daily AS and major cardiovascular risk factors (hypertension, age, body mass index, menopause duration), RA-specific risk factors (RA duration, erythrocyte sedimentation rate, and C-reactive protein), and psychoemotional status. Conclusion. 24-h ASM revealed that the patients with RA had higher vascular wall stiffness than the individuals in the comparison and control groups. Taking into consideration the pronounced changes in AS not only during the daytime, but also during the night, it is appropriate to perform daily monitoring in patients with RA in order to obtain more objective data

    Guidance on noncorticosteroid systemic immunomodulatory therapy in noninfectious uveitis: fundamentals of care for uveitis (focus) initiative

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    Topic: An international, expert-led consensus initiative to develop systematic, evidence-based recommendations for the treatment of noninfectious uveitis in the era of biologics. Clinical Relevance: The availability of biologic agents for the treatment of human eye disease has altered practice patterns for the management of noninfectious uveitis. Current guidelines are insufficient to assure optimal use of noncorticosteroid systemic immunomodulatory agents. Methods: An international expert steering committee comprising 9 uveitis specialists (including both ophthalmologists and rheumatologists) identified clinical questions and, together with 6 bibliographic fellows trained in uveitis, conducted a Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol systematic reviewof the literature (English language studies from January 1996 through June 2016; Medline [OVID], the Central Cochrane library, EMBASE,CINAHL,SCOPUS,BIOSIS, andWeb of Science). Publications included randomized controlled trials, prospective and retrospective studies with sufficient follow-up, case series with 15 cases or more, peer-reviewed articles, and hand-searched conference abstracts from key conferences. The proposed statements were circulated among 130 international uveitis experts for review.Atotal of 44 globally representativegroupmembersmet in late 2016 to refine these guidelines using a modified Delphi technique and assigned Oxford levels of evidence. Results: In total, 10 questions were addressed resulting in 21 evidence-based guidance statements covering the following topics: when to start noncorticosteroid immunomodulatory therapy, including both biologic and nonbiologic agents; what data to collect before treatment; when to modify or withdraw treatment; how to select agents based on individual efficacy and safety profiles; and evidence in specific uveitic conditions. Shared decision-making, communication among providers and safety monitoring also were addressed as part of the recommendations. Pharmacoeconomic considerations were not addressed. Conclusions: Consensus guidelines were developed based on published literature, expert opinion, and practical experience to bridge the gap between clinical needs and medical evidence to support the treatment of patients with noninfectious uveitis with noncorticosteroid immunomodulatory agents

    Cause of Death and Predictors of All-Cause Mortality in Anticoagulated Patients With Nonvalvular Atrial Fibrillation : Data From ROCKET AF

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    M. Kaste on työryhmän ROCKET AF Steering Comm jäsen.Background-Atrial fibrillation is associated with higher mortality. Identification of causes of death and contemporary risk factors for all-cause mortality may guide interventions. Methods and Results-In the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) study, patients with nonvalvular atrial fibrillation were randomized to rivaroxaban or dose-adjusted warfarin. Cox proportional hazards regression with backward elimination identified factors at randomization that were independently associated with all-cause mortality in the 14 171 participants in the intention-to-treat population. The median age was 73 years, and the mean CHADS(2) score was 3.5. Over 1.9 years of median follow-up, 1214 (8.6%) patients died. Kaplan-Meier mortality rates were 4.2% at 1 year and 8.9% at 2 years. The majority of classified deaths (1081) were cardiovascular (72%), whereas only 6% were nonhemorrhagic stroke or systemic embolism. No significant difference in all-cause mortality was observed between the rivaroxaban and warfarin arms (P=0.15). Heart failure (hazard ratio 1.51, 95% CI 1.33-1.70, P= 75 years (hazard ratio 1.69, 95% CI 1.51-1.90, P Conclusions-In a large population of patients anticoagulated for nonvalvular atrial fibrillation, approximate to 7 in 10 deaths were cardiovascular, whereasPeer reviewe
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