551 research outputs found
Separatrix splitting at a Hamiltonian bifurcation
We discuss the splitting of a separatrix in a generic unfolding of a
degenerate equilibrium in a Hamiltonian system with two degrees of freedom. We
assume that the unperturbed fixed point has two purely imaginary eigenvalues
and a double zero one. It is well known that an one-parametric unfolding of the
corresponding Hamiltonian can be described by an integrable normal form. The
normal form has a normally elliptic invariant manifold of dimension two. On
this manifold, the truncated normal form has a separatrix loop. This loop
shrinks to a point when the unfolding parameter vanishes. Unlike the normal
form, in the original system the stable and unstable trajectories of the
equilibrium do not coincide in general. The splitting of this loop is
exponentially small compared to the small parameter. This phenomenon implies
non-existence of single-round homoclinic orbits and divergence of series in the
normal form theory. We derive an asymptotic expression for the separatrix
splitting. We also discuss relations with behaviour of analytic continuation of
the system in a complex neighbourhood of the equilibrium
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STRA13 Interacts with STAT3 and Modulates Transcription of STAT3-dependent Targets
STRA13 is a pVHL-dependent bHLH transcription factor up-regulated on the mRNA level in multiple cancer cell lines and implicated recently in the regulation of immune cell homeostasis and autoimmunity. In searching for STRA13-interacting proteins with oncogenic potential by the yeast two-hybrid screening, we identified STAT3β as a STRA13-binding partner. We showed that STRA13 binds predominantly to phosphorylated (active) STAT3 α and β isoforms via its HLH and C-terminal regions. We also found that STRA13 was able to activate transcription from STAT-dependent cis-elements. Expression of endogenous STRA13 was shown to be cytokine-inducible, consistent with STRA13 involvement in STAT-dependent transcription regulation. We demonstrated that the STAT3-regulated promoter of the pro-apoptotic Fas gene was activated upon STRA13 over-expression and that co-expression of STRA13 with STAT3β or STAT3α modulated the transcriptional outcome. Forced expression of STRA13 induced apoptosis, in agreement with the STRA13 activation effect on the Fas promoter. Simultaneous expression of STRA13 and STAT3β resulted in alleviation of the STRA13 pro-apoptotic effect. Thus, for the first time, we identify STRA13 as a STAT3 partner and provide a consistent line of evidence for STRA13 involvement into regulation of apoptosis via the STAT pathways
The problem of obesity «through the eyes» of patients (results of the survey of patients of the outpatient registry)
Aim. To assess, based on the results of the questionnaire, patients' awareness of the presence, possible causes and health effects of overweight /obesity; to determine patients' self-assessment of their own weight, information about the methods used to treat the disease, adherence to therapy.Material and methods. The survey of patients of the outpatient registry was carried out as part of a face-to-face visit of inclusion in the observational study of EVA using a specially designed questionnaire. Out of 582 patients of the PROFILE registry who came for a visit in the period from 08.04.2019 to 24.03.2020, 295 people with a body mass index (BMI) were included in the study>25 kg/m2.Results. According to the BMI values, the patients of the study cohort were divided into 4 groups: 108 (36.6%) with pre-obesity, 124 (42.1%) with class I obesity, 42 (14.2%) with class II obesity, 21 (7.1%) with class III obesity. With an increase in the class of obesity, the number of patients who admit the presence of this pathology in self-assessment increases (p<0.0001): 26.6% of patients with grade I obesity, 47.6% with grade II obesity and 81% of patients with grade III obesity gave correct answers. Among the possible causes of overweight/obesity, every third patient of the study indicated physical inactivity (31.3%) and every fifth specified excessive nutrition (20.8%). The majority of patients, 244 (82.7%), believe that being overweight worsens their health, the same number of patients, 255 (86.4%), are sure that they need to lose weight. The most common (70% of responses) for weight loss patients used various dietary restrictions, fasting, only 17% of patients increased the level of physical activity. Frequent violation of the principles of rational nutrition was revealed (insufficient amount of fruits and vegetables in the diet, salting food, eating a large amount of easily digestible carbohydrates. One hundred and thirty nine (47.1%) patients noted that it was difficult for them to observe any restrictions in food, to adhere to a diethalf of all patients and 70% of patients with class III obesity experience a constant feeling of hunger. Of the 25 patients to whom pharmacotherapy was recommended, 21 (84%) people were adherent.Conclusion. Overweight and obese patients are not always critical of self-assessment of their body weight, and the main reasons for being overweight or obese considered to be inactivity and various violations of the principles of rational nutrition. The patients of the study cohort were characterized by eating disorders and half of the patients showed signs of food addiction. Recommendations for the pharmacotherapy of obesity were received by less than 10% of patients in the study cohort, while the patients' adherence to drug therapy was high
Parabolic resonances and instabilities in near-integrable two degrees of freedom Hamiltonian flows
When an integrable two-degrees-of-freedom Hamiltonian system possessing a
circle of parabolic fixed points is perturbed, a parabolic resonance occurs. It
is proved that its occurrence is generic for one parameter families
(co-dimension one phenomenon) of near-integrable, t.d.o. systems. Numerical
experiments indicate that the motion near a parabolic resonance exhibits new
type of chaotic behavior which includes instabilities in some directions and
long trapping times in others. Moreover, in a degenerate case, near a {\it flat
parabolic resonance}, large scale instabilities appear. A model arising from an
atmospherical study is shown to exhibit flat parabolic resonance. This supplies
a simple mechanism for the transport of particles with {\it small} (i.e.
atmospherically relevant) initial velocities from the vicinity of the equator
to high latitudes. A modification of the model which allows the development of
atmospherical jets unfolds the degeneracy, yet traces of the flat instabilities
are clearly observed
Syzygies in equivariant cohomology for non-abelian Lie groups
We extend the work of Allday-Franz-Puppe on syzygies in equivariant
cohomology from tori to arbitrary compact connected Lie groups G. In
particular, we show that for a compact orientable G-manifold X the analogue of
the Chang-Skjelbred sequence is exact if and only if the equivariant cohomology
of X is reflexive, if and only if the equivariant Poincare pairing for X is
perfect. Along the way we establish that the equivariant cohomology modules
arising from the orbit filtration of X are Cohen-Macaulay. We allow singular
spaces and introduce a Cartan model for their equivariant cohomology. We also
develop a criterion for the finiteness of the number of infinitesimal orbit
types of a G-manifold.Comment: 28 pages; minor change
Modulation of Localized States in Electroconvection
We report on the effects of temporal modulation of the driving force on a
particular class of localized states, known as worms, that have been observed
in electroconvection in nematic liquid crystals. The worms consist of the
superposition of traveling waves and have been observed to have unique, small
widths, but to vary in length. The transition from the pure conduction state to
worms occurs via a backward bifurcation. A possible explanation of the
formation of the worms has been given in terms of coupled amplitude equations.
Because the worms consist of the superposition of traveling waves, temporal
modulation of the control parameter is a useful probe of the dynamics of the
system. We observe that temporal modulation increases the average length of the
worms and stabilizes worms below the transition point in the absence of
modulation.Comment: 4 pages, 4 figure
Detection and Treatment of Hyperuricemia in Clinical Practice (According to the PROFILE Outpatient Registry)
Aim. To study the frequency of detection of hyperuricemia (HU) in patients with high and very high cardiovascular risk and the frequency of prescribing drugs that lower serum uric acid (sUA) levels in real clinical practice.Material and methods: The general information of the study was based on the data of 2457 patients who were consistently included in the «PROFILE» registry until November 30, 2020: 1250 men (50.9%) and 1207 (49.1%) women. All patients with HU were selected (UA level ≥360 pmol/l in women, ≥420 pmol/l in men). At the stage of inclusion of the patient, data on MC indicators were available in 1777 (72.3%), upon re-examination - only 262 (33.2%) out of 790 patients who returned to the appointment.Results: The most common study of the level of sUA was performed in patients with gout (65.2%), with arterial hypertension (AH) and dyslipemia in 29.1% of cases, with diabetes mellitus (DM) - 30.1%, with impaired tolerance to glucose (IGT) - 40.2%, with other diseases, the proportion of patients with a known UA was even less. A positive relationship was found between the presence of AH and IGT with the frequency of UA control (p<0.001). In patients with AH, an increase in the level of sUA was detected significantly more often than in patients without AH (p<0.001), and less frequently in patients with DM and IGT (p<0.001 and p<0.01, respectively). The frequency of allopurinol prescribing was low: 49 (2%) patients received therapy, while of the 284 patients with HU, only 20 (7%) were prescribed allopurinol.Conclusion: in real clinical practice, only 29.1% of patients with AH and 20-25% of patients with other CVDs were monitored for sUA levels, every third patient had data on sUA levels at a repeat visit. In the presence of gout, the proportion of patients with current UA was higher (65%). For those with AH and IGT, positive correlations were found between the presence of the disease and control of sUA levels. A low frequency of prescribing drugs for the correction of HU was revealed
Influence of through-flow on linear pattern formation properties in binary mixture convection
We investigate how a horizontal plane Poiseuille shear flow changes linear
convection properties in binary fluid layers heated from below. The full linear
field equations are solved with a shooting method for realistic top and bottom
boundary conditions. Through-flow induced changes of the bifurcation thresholds
(stability boundaries) for different types of convective solutions are deter-
mined in the control parameter space spanned by Rayleigh number, Soret coupling
(positive as well as negative), and through-flow Reynolds number. We elucidate
the through-flow induced lifting of the Hopf symmetry degeneracy of left and
right traveling waves in mixtures with negative Soret coupling. Finally we
determine with a saddle point analysis of the complex dispersion relation of
the field equations over the complex wave number plane the borders between
absolute and convective instabilities for different types of perturbations in
comparison with the appropriate Ginzburg-Landau amplitude equation
approximation. PACS:47.20.-k,47.20.Bp, 47.15.-x,47.54.+rComment: 19 pages, 15 Postscript figure
Challenges of Statin Therapy in Clinical Practice (According to Outpatient Register «PROFILE» Data)
Aim. To identify the main problems of statin therapy in patients with high and very high cardiovascular (CV) risk in real clinical practice.Material and methods. The general information of the study was based on data from 2,457 patients who were included in the register before November 30, 2020: 1,250 men (50.9%) and 1,207 (49.1%) women. A more detailed analysis was performed for groups of patients with high         and very high CV risk who had indications for statin treatment at the time of inclusion in the register: out of 2457 patients, 1166 people had very high CV risk, 395 was at high CV risk (a total of 1561 people, the average age of patients was 64.4±11.0 years).Results. Information on the parameters of the lipidogram – the level of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) was available in 1918 (78.1%) and 1546 (62.9%) patients, respectively. Of 1561 patients with high and very high CV risk, TC and LDL-C levels were analyzed in 1221 (78.2%) and 956 (61.2%) cases, statistically significantly more often in patients with high CV risk (p<0.05). Statins were recommended only to 823 (52.7%) patients with high and very high CV risk. Patients with very high CV risk received such appointments 4 times more often than patients with high CV risk: odds ratio (OR) 4.2; 95% confidence interval (CI) 3.2-5.3 (p<0.001). Doctors preferred atorvastatin in prescriptions (n=456, 55.4%), rosuvastatin (n=244, 29.7%) and simvastatin (n=121, 14.7%) were in second and third places. The target level of LDLC was 2 times more often achieved in patients with high CVR, compared with patients with very high CV risk: OR = 2.0, 95% CI 1.4-3.0 (p<0.001).Conclusion. The main problems of statin treatment in real clinical practice remain the non-assignment of these drugs to patients who have indications for such therapy and the failure to achieve the target levels of lipidogram indicators, which may probably be due to the clinical inertia of doctors regarding titration of statin doses, and in some cases caused by the choice of drugs that are not the most effective in reducing LDL cholesterol. Patients with very high CV risk are 4 times more likely to receive a recommendation to take statins compared to patients with high CV risk, but the target level of LDL cholesterol is reached in them 2 times less often
STUDY OF THE PARAMETERS OF TOLERABILITY AND ADHERENCE TO THERAPY IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE AND ARTERIAL HYPERTENSION ON THE BACKGROUND OF TREATMENT WITH FIXED COMBINATION OF RAMIPRIL AND AMLODIPINE (ACCORDING TO THE RESULTS OF OBSERVATIONAL STUDY "GRANAT-2")
Working group of the “GRANAT-2” study: Tula - Trubitsyn G.I., Ivanov Yu.V., Mirenkova O.K., Eskova R.A., Simonova R.P., Milon M.E., Telegina E.V., Kuznetsov A.M., Zhukova N.A., Zainullina I.K.; Rostov-on-Don - Budanov O.V., London E.M., Minosyan L.V., Nedashkovskaya N.G., Ter-Ananyants Ye.A.; Tomsk - Proskokova I.Yu., Permyakova O.V., Politova L.V., Maneeva I.D., Ivanova S.Yu.; Nizhny Novgorod - Larina O.V., Pokrovskaya I.N., Patselt E.A.; Moscow - Sladkova T.A., Zelenova Т.V. Aim. To study the tolerability and adherence to antihypertensive therapy in patients with hypertension and chronic obstructive pulmonary disease (COPD) using the fixed combination of ramipril and amlodipine in the observational program for patients with arterial hypertension and COPD (GRANAT-2). Material and methods. Patients with hypertension and COPD (n=52) with all inclusion criteria and without exclusion criteria who signed informed consent to participate in the GRANAT-2 program were included into the study. The use of a fixed combination of ramipril and amlodipine was recommended in all patients. The doses were determined by the treating physicians in accordance with the official drug instruction. The patients had 4 visits, and the duration of the study was 5 months. The Morisky-Green test was used to assess an adherence of patients to treatment. Assessments of blood pressure, adverse events were performed at all visits. Results. 50 of 52 patients completed the study: 45 patients used the studied fixed combination in the recommended doses, and 5 patients used other antihypertensive drugs, 2 patients withdrew from the study. Systolic blood pressure after 1 month of treatment decreased by an average of 20 mm Hg from the baseline, and diastolic blood pressure – by 10 mmHg. These rates after 5 months of therapy were 29 mm Hg and 15 mm Hg, respectively. Target blood pressure level was achieved in all patients. Increase in adherence of patients to treatment (according to the Morisky-Green test from 21.1% to 65.1%) was found. 2 cases of adverse events (dry cough) were registered. The discrepancy in adherence assessment was revealed between the results from the Morisky-Green test and the data from program case report forms. Conclusion. Regular patient visits to the doctor and the rapid achievement of an antihypertensive effect with good tolerability of a fixed combination of ramipril and amlodipine contributed to the increase in adherence of patients to treatment. Undesirable effects of the drug therapy are significant, but not leading factors that have a negative impact on the patient adherence to treatment
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