Dynamics of the Free Surface of a Conducting Liquid in a Near-Critical Electric Field

Near-critical behavior of the free surface of an ideally conducting liquid in an external electric field is considered. Based on an analysis of three-wave processes using the method of integral estimations, sufficient criteria for hard instability of a planar surface are formulated. It is shown that the higher-order nonlinearities do not saturate the instability, for which reason the growth of disturbances has an explosive character.Comment: 19 page

Clinical and instrumental associations of knee osteoarthrosis and pathology of the veins of the lower extremities

Knee osteoarthritis (OA) and varicose disease of the lower extremities (VD) are two diseases common in middle– aged and older women. Questions about whether their combination is accidental or natural and whether VD affects the course and severity of OA, remain unresolved.The aim of the study was to look for the possible association between knee OA and lower limb vein pathology on the basis of clinical and modern instrumental investigation sand to study the effect of the VD on the clinical manifestations and severity of knee OA.Materials and methods. A case-control study was conducted in 85 women 40–60 years old with knee OA diagnosed in accordance with the criteria of ACR (1986) and 50 women of the same age without signs of knee OA. Women of both groups were evaluated for complaints and objective examination with an emphasis on diseases of the joints and veins of the lower extremities, radiography of the knee joints, ultrasound duplex scanning of the veins of the lower extremities. The severity of OA was assessed by the Lequenne indices. The clinical assessment of venous pathology was carried out according to the CEAP classification.Results. Patients with knee OA more often than their peers without joint pathology have VD (43% vs 22%; p=0.015), signs of chronic venous insufficiency (28% vs 12%; p=0.03), as well as valve failure of several lower limb veins simultaneously (53% vs 20%; p=0.0004). After correction by body mass index, the association of knee OA with detected vascular pathology remained clinically and statistically significant. The presence of VD with moderate manifestations of chronic venous insufficiency, as well as ultrasound signs of venous pathology, was not associated with the clinical signs and course of knee OA.Conclusions. Knee OA in middle-aged and older women, regardless of body mass index, is associated with VD and ultrasound signs of simultaneous valves failure of several veins. Manifestations of chronic venous insufficiency did not affect the clinical picture and severity of knee OA

Comparative performance of selected variability detection techniques in photometric time series

Photometric measurements are prone to systematic errors presenting a challenge to low-amplitude variability detection. In search for a general-purpose variability detection technique able to recover a broad range of variability types including currently unknown ones, we test 18 statistical characteristics quantifying scatter and/or correlation between brightness measurements. We compare their performance in identifying variable objects in seven time series data sets obtained with telescopes ranging in size from a telephoto lens to 1m-class and probing variability on time-scales from minutes to decades. The test data sets together include lightcurves of 127539 objects, among them 1251 variable stars of various types and represent a range of observing conditions often found in ground-based variability surveys. The real data are complemented by simulations. We propose a combination of two indices that together recover a broad range of variability types from photometric data characterized by a wide variety of sampling patterns, photometric accuracies, and percentages of outlier measurements. The first index is the interquartile range (IQR) of magnitude measurements, sensitive to variability irrespective of a time-scale and resistant to outliers. It can be complemented by the ratio of the lightcurve variance to the mean square successive difference, 1/h, which is efficient in detecting variability on time-scales longer than the typical time interval between observations. Variable objects have larger 1/h and/or IQR values than non-variable objects of similar brightness. Another approach to variability detection is to combine many variability indices using principal component analysis. We present 124 previously unknown variable stars found in the test data.Comment: 29 pages, 8 figures, 7 tables; accepted to MNRAS; for additional plots, see http://scan.sai.msu.ru/~kirx/var_idx_paper

Eclipsing variable stars in the Moscow program for scanning the astronomical plate stacks

Рассматриваются результаты полуавтоматического поиска затменных переменных звезд по сканам московской коллекции астронегативов и особенности распределения обнаруженных затменных переменных по периодам.We consider the results of our semi-automated search for eclipsing variables using scans of the Moscow astronomical plate stacks and characteristics of the eclipsing variables’ distribution over periods

Antimicrobial resistance in clinical <I>Escherichia coli</I> isolates obtained from animals

The article presents data on the phenotypic and genotypic characteristics of antimicriobial resistance in Escherichia coli clinical isolates recovered from bovine microbiota (secretions from mammary glands, cervical swabs). 127 Escherichia coli isolates were studied, i.e. 44 from mammary glands secretions and 83 from cervical swabs. Disk diffusion method was used to study antimicrobial resistance of the cultures; minimum inhibitory concentrations of antimicrobials were determined in a serial dilution method; resistance genes were detected by polymerase chain reaction. The carried out research demonstrates a wide distribution of the isolates belonging to the phenotype resistant to ansamycins (rifampicin), semi-synthetic penicillins (ampicillin and amoxicillin), tetracyclines (doxycycline). The isolates showed a lower level of resistance to macrolides (azithromycin), amphenicols (levomycetin) and aminoglycosides (tobramycin). It was found that Escherichia coli clinical isolates are sensitive to third-generation cephalosporins and fluoroquinolone antimicrobials. However, since 28.46% of cultures demonstrate intermediate resistance to third-generation cephalosporins and 49.02% of Escherichia coli DNA samples isolated from mammal gland secretions had blaDHA gene associated with resistance to this group of antimicrobials, these antimicrobials could be hardly recommended as antibiotics of choice. Absence of VIM carbapenemase-encoding gene in the DNA of the recovered isolates and a low level of phenotypic resistance (10.22% of isolates from cervical swabs) can be one of the reasons for recommending first-line carbapenems as antibiotics of choice to treat animal diseases associated with Escherichia coli, along with fluoroquinolones as reserve antimicrobials. It was found that the recovered Escherichia coli isolates are more sensitive to combination antibiotics than to mono-antibiotics