Temporal response to harmonic driving in electroconvection

The temporal evolution of the spatially periodic electroconvection (EC) patterns has been studied within the period of the driving ac voltage by monitoring the light intensity diffracted from the pattern. Measurements have been carried out on a variety of nematic systems, including those with negative dielectric and positive conductivity anisotropy, exhibiting "standard EC" (s-EC), those with both anisotropies negative exhibiting "non-standard EC" (ns-EC), as well as those with the two anisotropies positive. Theoretical predictions have been confirmed for stationary s-EC and ns-EC patterns. Transitions with Hopf bifurcation have also been studied. While traveling had no effect on the temporal evolution of dielectric s-EC, traveling conductive s-EC and ns-EC patterns exhibited a substantially altered temporal behavior with a dependence on the Hopf frequency. It has also been shown that in nematics with both anisotropies positive, the pattern develops and decays within an interval much shorter than the period, even at relatively large driving frequencies.Comment: 19 pages, 5 figure

Three-dimensional pattern formation, multiple homogeneous soft modes, and nonlinear dielectric electroconvection

Patterns forming spontaneously in extended, three-dimensional, dissipative systems are likely to excite several homogeneous soft modes ($\approx$ hydrodynamic modes) of the underlying physical system, much more than quasi one- and two-dimensional patterns are. The reason is the lack of damping boundaries. This paper compares two analytic techniques to derive the patten dynamics from hydrodynamics, which are usually equivalent but lead to different results when applied to multiple homogeneous soft modes. Dielectric electroconvection in nematic liquid crystals is introduced as a model for three-dimensional pattern formation. The 3D pattern dynamics including soft modes are derived. For slabs of large but finite thickness the description is reduced further to a two-dimensional one. It is argued that the range of validity of 2D descriptions is limited to a very small region above threshold. The transition from 2D to 3D pattern dynamics is discussed. Experimentally testable predictions for the stable range of ideal patterns and the electric Nusselt numbers are made. For most results analytic approximations in terms of material parameters are given.Comment: 29 pages, 2 figure

Evaluation of myocardial damage in different types of rheumatoid arthritisduring disease-modifying antirheumatic drug or biological therapy (with infliximab)

Objective. To estimate the extent and pattern of myocardial damage in different types of rheumatoid arthritis (RA) during disease-modifying antirheumatic drug (DMARD) or biological therapy. Subjects and methods. Seventy-one patients with RA were examined; some of them received biological therapy with infliximab, while the others took DMARDs. A group of patients with incipient RA was also identified. B-type brain natriuretic peptide levels were estimated and electrocardiography, echocardiography (EchoCG), and cardiac magnetic resonance imaging (MRT) using the contrast medium Dotarem were conducted in all the patients. The follow-up totaled 6 months. A control examination was made at the moment of randomization and 6 months posttreatment. Results. Tn the bulk of patients, the level of B-type brain natriuretic peptide did not differ from the reference values, however, its lower level was observed in the incipient RA group, which was associated with the absence of cardiovascular diseases and with a younger age group. There were no negative EchoCG changes in myocardial viability values. Cardiac MRT demonstrated that the majority of patients had the similar changes that failed to affect myocardial kinetics and ejection fraction. These changes were not found in incipient RA patients without cardiovascular diseases. No improvement in myocardial viability was recorded in the patients receiving the biological therapy. Conclusion. Thus, cardiac MRT showed the similar changes that failed to affect myocardial kinetics and ejection fraction in patients with RA during both methotrexate and infliximab therapy

IDENTIFICATION AND STUDY OF LEPTOSPIROSIS FOCUS IN IRKUTSK REGION

Due to examination of animal breeding workers at the Irkutsk Region a case of human leptospirosis was identified. at the cattle farm of Tugutuy settlement. Due to epizootological-epidemiological study a mixed, leptospirosis focus in Ekhirit-Bulagat district was established, the agent circulation among commensal and wild, small mammals was demonstrated. Continuous pathogenic Leptospira DNA detection during the second, half of 2011, as well as the positive tularemia laboratory results require further study of the focus

Функциональная МРТ в оценке изменений коннектома головного мозга у пациенток с постмастэктомическим синдромом

Introduction. In the postoperative period after total mastectomy, patients develop postmastectomy syndrome, including upper limb lymphedema and a number of neuropsychiatric disorders that affect the functional state of the brain and reduce the quality of life.Purpose of the study. Evaluation of changes in functional connectivity of the default mode network in patients with post-mastectomy syndrome using resting state functional MRI.Materials and methods. Resting state functional MRI was performed to 46 patients aged 30 to 50 years with neurological disorders in the late postoperative period (>6 months) after radical mastectomy for breast cancer, as well as 20 healthy women from the control group.Results. According to the intergroup statistical analysis, there were differences in functional connectivity of the default mode network in all 46 patients with post-mastectomy syndrome, compared to the control group (p<0,01).Conclusion. The revealed changes in the functional connectivity of the default mode network of the brain indicate the functional reorganization of the brain connectome in patients with neurological manifestations of post-mastectomy syndrome. Введение. В послеоперационном периоде после тотальной мастэктомии у большинства пациенток развивается постмастэктомический синдром, включающий лимфедему верхней конечности и ряд психоневрологических нарушений, оказывающих влияние на функциональное состояние головного мозга и снижающих качество жизни.Цель исследования: оценка изменений функциональной коннективности в сети пассивного режима работы мозга у пациенток с постмастэктомическим синдромом с использованием функциональной МРТ в состоянии покоя.Материалы и методы. Функциональная МРТ в состоянии покоя выполнялась 46 пациенткам в возрасте от 30 до 50 лет с  неврологическими расстройствами в  позднем послеоперационном периоде (>6 мес) после радикальной мастэктомии по поводу рака молочной железы, а также 20 здоровым женщинам из группы контроля.Результаты. Согласно межгрупповому статистическому анализу, у всех 46 пациенток с постмастэктомическим синдромом были выявлены различия в функциональной коннективности сети пассивного режима работы мозга по сравнению с контрольной группой (р<0,01).Заключение. Выявленные изменения коннективности сети пассивного режима работы мозга свидетельствуют о функциональной реорганизации коннектома головного мозга у пациенток с неврологическими проявлениями постмастэктомического синдрома.

ELECTROHYDRODYNAMIC INSTABILITIES IN THE LIQUID CRYSTALLINE PHASES WITH SMECTIC ORDERING

On a étudié les variations avec la fréquence de la tension seuil d'instabilités apparaissant dans les couches de cristal liquide en orientation homogène ou homéotrope soumises à un champ électrique alternatif. Les cristaux liquides ont des phases nématiques ainsi que des phases smectiques A et leur anisotropie de conductivité électrique change de signe à une température faiblement supérieure à celle de la transition nématique-smectique A. Des données expérimentales sont expliquées à l'aide du mécanisme isotrope et du mécanisme de Carr et Helfrich.An investigation has been made of the frequency characteristics of the threshold voltage of domain instabilities induced by an electric field in both homogeneously and homeotropically oriented liquid crystal layers. The mesogens had the nematic and smectic A phases and their anisotropy of the electrical conductivity changed its sign at the critical temperature somewhat above the nematic-smectic transition point. All the instabilities observed were of the electrohydrodynamic nature. The experimental results were accounted for in terms of the isotropic and Carr-Helfrich mechanisms

Diamond Burr Polishing of Bowman’s Layer in the Treatment of Subepithelial Fibrosis after Radial Keratotomy (Clinical Case)

Radial keratotomy (RK) was widely used at the end of the last century for refractive purposes. However, ophthalmologists are increasingly faced with negative long-term consequences after RK now. A relatively rare complication after RK is subepithelial fibrosis (according to some data, it occurs in 2.7 % of cases), which may be the result of abnormal activation or proliferation of stromal keratocytes (stromal fibroblasts) after surgical or accidental injury of the Bowman membrane. Phototherapeutic keratectomy and manual mechanical removal by the “scraper” are used for the removal of fibrous tissue, as well as a combination of these methods with mitomycin. Since laser energy can provoke a recurrence of fibrosis in the future due to the activation of stromal keratocytes and using “scraper” is not always possible to remove fibrotic tissue and the use of mitomycin is associated with a number of complications, the question of finding new methods for its removal with minimal risk of complications arises. The method of diamond burr polishing of the cornea, which developed by us for treating the syndrome of recurrent cornea erosion, was, in our opinion, the most optimal for this purpose. The method of diamond burr polishing of the cornea in this clinical case made it possible to remove the epithelial fibrosis zone without damaging the Bowman’s layer, thereby avoiding the recurrence of fibrosis in the postoperative period (the follow-up period was 2 years). The depth of the location pathological tissue location was assessed using the OCT of the cornea. The absence of recurrence is also confirmed biomicroscopically and with the OCT of the cornea. So, the method of diamond burr polishing of the Bowman’s layer can be a method of choice for the treatment of subepithelial fibrosis for patients after keratorefractive operations, being highly effective, accessible, easy to perform

Susceptibility-weighted MR imaging (SWI) of basal ganglia iron deposition in the early and advanced stages of Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease and the first one among the nosological entities of parkinsonism. Susceptibility-weighted imaging (SWI), magnetic resonance imaging (MRI) pulse sequence, which allows the in vivo estimation of the values of iron deposition in different areas of the brain, is a potential technique for the early diagnosis of PD and for the study of the pathogenesis of its complications.Objective: to compare the values of iron deposition in the basal ganglia in Stages II and III PD and to determine the relationship of clinical findings to the level of iron deposition according to the SWI findings.Patients and methods. Twenty-four patients with Hoehn and Yahr Stages II (n=24) and III (n=12) PD were examined. All the patients underwent brain MRI on a Siemens TrioTim (3T) MRI scanner by using pulse sequences T1, T2, SWI and subsequently quantifying the iron deposition (SPIN software). The accumulation of iron is visualized as an area of reduced signal intensity on SWI, and its estimation in accordance with the SPIN program has accordingly a smaller value. The regions of interest on both sides were the dentate nucleus, substantia nigra, red nucleus, putamen, globus pallidus, and head of the caudate nucleus. The examination protocol also included tests using the following scales: the Unified Parkinson's Disease Rating Scale (UPDRS), the Mini-Mental State Examination (MMSE), Frontal Assessment Batter (FAB), Freezing of Gait (FOG), Gait and Balance Scale (GABS), the Epworth Daytime Sleepiness Scale, the Parkinson's Disease Quality of Life Questionnaire (PDQ), the Beck Depression Inventory, and the Clock-Drawing Test.Results and discussion. The investigators found significant (p<0.05) correlations between the clinical picture and the level of iron deposition in the regions of interest in patients with Stage II PD: FOG – left caudate nucleus (r=-0.94); GABS – left caudate nucleus (r=-0.94); and in patients with stage III of the disease: UPDRS (full) – left red nucleus (r=-0.82), right globus pallidus (r=-0,80), left putamen (r=-0,96); UPDRS (Section 2) – left red nucleus (r=-0.77), left globus pallidus (r=-0.84); UPDRS (Section 3) – right putamen (r=-0,85), right globus pallidus (r=-0.78), left globus pallidus (r=-0,92); FOG – left globus pallidus (r=-0.81); GABS – left red nucleus (r=-0.96), left putamen (r=0.82), right putamen (r=-0.89), left globus pallidus (r=-0.82), right globus pallidus (r=-0.85), left caudate nucleus (r=-0.82), right caudate nucleus (r=-0.89); Beck Depression Inventory – right substantia nigra (r=-0.82).Conclusion. SWI measurement of the values of iron deposition in the structures of the extrapyramidal system in PD provides an additional insight into the pathological processes occurring in them