Market of Stocks During Crisis Looks Like a Flock of Birds

According to its inner property, a crisis in the financial market can be considered as a collective behavior phenomenon. Through the prism of collective behavior, the crisis does not happen if the companies are independent of each other. In this work, cooperative movement processes in a stock market are investigated in a manner similar to that Vicsek first described collective behavior for self-propelled entities. To this end, a phase space is defined as the one in which the return of volume of transactions versus return of price is represented with each share in each day corresponding to a unique point in the space. The findings of the observation show that during times of crisis, the phase space is limited with the vector velocity of shares in the same direction. In contrast, on a regular day, the phase space is entirely accessible, with vector velocity aligned randomly. Moreover, in line with the Vicsek model, an order parameter is introduced, which evaluates the cooperative effects for the shares so that the higher the value of this parameter, the stronger the collective behavior of the shares.

A Comparison of the Flow Structure in a Normal Triangular Tube Array Obtained Based on the SFV Technique and on a CFD Analysis

This paper presents an analysis of the performance of the Spatial Filter Velocimetry (SFV) technique applied to external flows across tube bundles to evaluate the benefits of using low particle concentration in a complex geometry. The experimental vector velocity fields were obtained in a tube bundle test section made of acrylic with 20 rows of 4 tubes of 20mm O.D. mounted in a normal triangular configuration and transversal pitch per diameter ratio of 1.25. The SFV results reliability was evaluated by comparing the volumetric flow rates estimated by the experimental vector velocity fields with the volumetric flow rates measured by the flowmeter, showing good agreement. Additionally, the experimental results are used to check the validity of numerical results obtained through CFD simulation. The experiments were conducted for Reynolds numbers of 909, 1842 and 3902. The velocity profiles obtained through the SFV technique agree with the CFD simulations results, which indicate consistent results for both analyzes. Therefore, the numerical and experimental results indicate that the SFV technique provides accurate velocity data and is suitable to be applied to complex geometries, especially in regions away of the test section wall due to the good visibility provided by low particle concentration.

Results analysis of the tests and certification of near-airfield meteorological radar complex

The article presents the tasks, characteristic features, tactical and technical characteristics, the possible location and scope of the near-airfield meteorological radar complex. The analysis is made of the comparison of meteorological radar data from the near-airfield meteorological radar complex with reliable sources of meteorological information obtained during preliminary, acceptance, certification tests. The features of carrying out during the validation tests of meteorological radar data of the near-airfield meteorological radar complex are described, namely: dangerous meteorological phenomena (showers of different intensities, thunderstorms with a probability of 30-70%, 71-90%, > 90%, hail of varying degrees of intensity, squall of different intensities), velocity and direction of movement of cloud formations, vector velocity field. Examples of comparing the data of the near-airfield meteorological radar complex with data from a priori reliable sources of information are shown in the form of maps, graphs and tables. It is shown that the data of the near-airfield meteorological radar complex were obtained during testing and certification covering the warm and cold periods of the year, the sample size is statistically significant (except for the sample to assess the vector velocity field from data of aircraft and radar due to the spatial-temporal features comparing data from the two indicated information sources). It was established that the near-airfield meteorological radar complex provides acceptable in accordance with the requirements the construction quality of meteorological phenomena maps, the vector velocity field and the estimation of the cloud formations movement vector. The article illustrates the results of the statistical analysis of the data of the near-airfield meteorological radar complex, obtained personally by the author of the article. Analysis of meteorological data of the near-airfield meteorological radar complex was carried out with the aim of further exploitation of the near-airfield meteorological radar complex.

P1771Right ventricular mechanical changes after septal myectomy for obstructive hypertrophic cardiomyopathy. Vector velocity imaging study

Objectives The impairment of right ventricular (RV) myocardial mechanics is evident in hypertrophic cardiomyopathy (HCM). It is independently influenced by LV mechanics and correlated to the severity of LV phenotype. We investigated the changes in RV global and regional deformation following surgical septal myectomy using vector velocity imaging (VVI). Methods 25 HCM patients, 68% males with mean age (34.5±12 years) were examined before and within two months after surgical myectomy using VVI. In addition to conventional echocardiographic parameters, peak systolic strain (εsys), strain rate (SR) and time to peak εsys (TTP) of regional RV free wall (RVFW) & septal walls were analyzed in longitudinal (long) directions from apical four chamber view and their (Δ)changes were calculated. Similar parameters were quantified in LV from apical 2 & 4 CH views. Intra-V-delay was defined as SD of TTP and inter-V dyssynchrony was estimated from TTP difference between the most delayed LV segment & RVFW. Results All study patients showed improvement of their functional class from NYHA class III to class I and reduction of LVOT gradient to below 20 mmHg except one patient who had 30 mmHg gradients at rest. There was significant reduction of septal thickness, left atrial diameter& volume, LVOT gradient, LVMI, severity of mitral regurgitation, tricuspid annular velocities (P<0.0001), RV diameter (P<0.02) and increase in LV internal dimensions (P<0.001) post myectomy. However, there was significant reduction of RV and LV systolic mechanics; RV global εsys % (from −16.1±4.4 to −12.9±2.9, P<0.0001) and LV global εsys %: from −11.6±2.8 to −9.4±2.2%, P<0.0001) respectively. The magnitude of reduction of RV strain (Δ RV εsys%, Δ SRsys) was directly correlated LV maximal wall thickness (r=0.46, P<0.01) and ΔRV dyssynchrony (TTP-SD), (r=0.4, P<0.05) and negatively correlated to age (r=−0.46, P<0.02), pre-op RV SRsys (r=−0.52, P<0.01) and pre-op LV EF% (r=−0.43, P<0.03). Meanwhile the reduction in RV diastolic mechanics: Δ RV SRe & SRa were directly correlated to PAP and LVOT gradient before surgery (r=0.62, P<0.002). Conclusion Despite improvement of patient functional status and reduction LVOT gradient, RV mechanics shows further deterioration after surgical myectomy. The magnitude of reduction is modestly related to cardiac phenotype and pre-op mechanical function.