A theoretical model of a wake of a body towed in a stratified fluid at large Reynolds and Froude numbers

International audienceThe objective of the present paper is to develop a theoretical model describing the evolution of a turbulent wake behind a towed sphere in a stably stratified fluid at large Froude and Reynolds numbers. The wake flow is considered as a quasi two-dimensional (2-D) turbulent jet flow whose dynamics is governed by the momentum transfer from the mean flow to a quasi-2-D sinuous mode growing due to hydrodynamic instability. The model employs a quasi-linear approximation to describe this momentum transfer. The model scaling coefficients are defined with the use of available experimental data, and the performance of the model is verified by comparison with the results of a direct numerical simulation of a 2-D turbulent jet flow. The model prediction for the temporal development of the wake axis mean velocity is found to be in good agreement with the experimental data obtained by Spedding (1997)

ДИАГНОСТИКА НАРУШЕНИЙ В СИСТЕМЕ ГЕМОСТАЗА ПРИ ПРИМЕНЕНИИ ВАРФАРИНА У БОЛЬНЫХ КАРДИОХИРУРГИЧЕСКОГО ПРОФИЛЯ

Objective: to reveal early changes in the hemostatic system during warfarin therapy in cardiac surgical patients, by comprehensively evaluating their hemostatic status.Subjects and methods. Seventyfive patients receiving cardiac surgical treatment were examined. All the patients took warfarin for 5±1.5 days. Laboratory studies involving the determination of routine coagulogram readings and thrombodynamic indicators (lag time (Tlag) and rate (Vs) of clot growth, and concentrations of individual Factors II, VI, IX, and X) were used to evaluate the patients' hemostatic status.Results. 28% of the patients were found to have an international normalized ratio (INR) of above 3.0. There was a correlation of Tlag with INR (R2=0.66). Both indicators were  comparatively highly correlated with Factor II and Factor X concentrations (R2=0.50 and 0.40 for Tlag; R2=0.53 and 0.48 for INR) and were uncorrelated with Factor IX levels (R2=0.20 for Tlag and 0.34 for INR). However, there was a difference in Factor VII concentrations: no correlation for Tlag (R2=0.20) whereas it for INR was rather high (R2=0.42). The index Vs was uncorrelated with INR (R2=0.24) and the concentration of blood coagulation factors (R2<0.1). There was a high correlation between Factor II and Factor X concentrations (R2=0.87); the correlation between the concentrations of all other pairs of coagulation factors was substantially lower (R20.45). The lack of correlation of a thrombodynamic indicator, such as clot growth rate, with the concentration of coagulation factors points to the fact that warfarin acts mainly on the phase of coagulation activation rather than that of clot propagation.Conclusion. The weak correlation between coagulation factors (except that of a pair of Factor II and Factor X) is indicative of the individual response of the patients to warfarin treatment and the need to monitor the hemostatic status by global hemostatic tests rather than by individual proteins. The thrombodynamic indicator Tlag reflects the effect of warfarin in proportion to INR. Warfarin virtually fails to affect the rate of clot growth so this indicator may be used to evaluate the patient's procoagulant status uncompensated for with warfarin intake. Цель работы. Выявление ранних изменений в системе гемостаза при терапии варфарином у кардиохирургических больных путем комплексной оценки гемостатического статуса пациентов.Материалы и методы. Исследовано 75 пациентов, проходивших кардиохирургическое лечение. Все пациенты получали варфарин (продолжительность лечения больных — 5±1,5 суток). Для оценки гемостатического статуса больных использовали лабораторные методы, включающие определение рутинных показателей коагулограммы, тромбодинамики (время задержки Tlag и скорости роста сгустка (Vs), исследования концентрации II, VII, IX, X факторов).Результаты. Установлено, что у 28%больных показатель МНО находился в области свыше 3.0. Установлена корреляция Tlag с  MНО (R2=0,66). Оба показателя имеют сравнительно высокую корреляцию с концентрацией FII и FX (R2=0,50 и 0,40 для Tlag, R2=0,53 и 0,48 для МНО) и не коррелируют с концентрацией FIX (R2=0,20 для Tlag и 0,34 для МНО). Однако наблюдается расхождение в случае концентрации FVII: корреляция для Tlag отсутствует (R2=0,20), тогда как для МНО она достаточно высока (R2=0,42). Параметр Vs не коррелирует с МНО (R2=0,24) и концентрацией факторов свертывания (R2<0,1). Обнаружена высокая корреляция между концентрациями факторов FII и FX (R2=0,87), корреляция между концентрациями всех других пар факторов свертывания существенно ниже (R20,45). Отсутствие корреляции такого показателя тромбодинамики как скорость роста сгустка от концентрации факторов указывает на то, что варфарин действует преимущественно на фазу активации свертывания, но не на фазу распространения сгустка.Заключение. Слабая корреляция факторов свертывания между собой (за исключением пары фактор II — фактор X) указывает на индивидуальный ответ больных на лечение варфарином и необходимость мониторинга состояния гемостаза не по отдельным белкам, а глобальными тестами. Параметр Tlag в тромбодинамике отражает эффект варфарина пропорционально МНО. Варфарин практически не влияет на скорость роста сгустка Vs, поэтому данный параметр можно использовать для оценки прокоагулянтного состояния пациента, не компенсируемого приемом варфарина

INVESTIGATION OF ANTIFUNGAL ACTIVITY OF QUINOLINIUM DERIVATIVES

Abstract. Antifungal activity (Candida albicans, Candida krusei) of some substituted quinolinium derivatives has been investigated. It was established that the most perspective compound for detail investigation of antifungal activity by labeled biomarkers method was N-phenylbenzoquinaldinium tetrafluoroborate

A Rotating Knife-beam Altimeter for Wide-swath Remote Sensing of Ocean: Wind and Waves

The use of a nadir altimeter radar with a rotating knife-beam antenna pattern isconsidered for improved measurements of the sea surface wind and wave parameters over awide swath. Theoretical calculations suggest the antenna beam rotating about the verticalaxis is able to provide wide swath of order 250-350 km. Processing of the signals using timeor Doppler sampling techniques results in the division of the antenna footprint intoelementary scattering cells of the order of 14x14 km. The theoretical algorithms developedhere indicate that the system may be used to retrieve the variance of large-scale slopes, thedirection of wave propagation and the wind speed in each cell. The possibility of measuringsignificant wave height is also analyzed. The combination of linear motion of the radar andthe rotation of the knife-beam antenna can be exploited to build up a two-dimensional mapof the surface, which enables better understanding of wave processes and to study theirstructure and temporal dynamics using repeated observations

MOLD FUNGI OF OF HOSPITAL ROOMS

Growth of number of the diseases caused by mold fungi is noted around the world. These diseases can be acquired by patients directly in hospitals in the course of hospitalization. The wide circulation of mold fungi in the hospital environment of a hospital is revealed