Automatic detection of coronaries ostia in computed tomography angiography volume data

Background: Heart coronaries emerge from the ascending aorta lateral sides from two points called the coronaries ostia. To automatically segment the heart coronaries; there must be a starting point (seed) for the segmentation. In this paper we present a fully automatic approach to segment the coronaries ostia towards automatic seeding for heart coronaries segmentation.Methods: Our algorithm takes as an input a CTA volume of segmented aorta cross sections that represents our region of interest. Then the ostia detection algorithm traverses that volume looking for the ostia points in an automatic fashion. The proposed algorithm depends on the anatomical features of the ostia. The main anatomic feature of the ostia is that it appears like a curvature or corner on the segmented ascending aorta cross section. Therefore we adopted in our methodology a modified version of Harris Corner Detection; besides inducing some anatomical features of the ostia location with respect to the aortic valve.Results: The proposed algorithm is tested and validated on the computed tomography angiography database provided by the Rotterdam coronary artery algorithm evaluation framework. The proposed automatic ostia detection algorithm succeeded to detect both ostia points in all the test cases. Also, the detected ostia points’ coordinates are validated versus a ground truth provided by the same framework with deviation between the results of the detection process and the ground truth having a min of 0 pixels and a max of 10 pixels for all test cases.Conclusions: Thus the proposed algorithm gives accurate results in comparison with the ground truth, which proves the efficiency of the proposed algorithm and its applicability to be extended as a seed for heart coronaries segmentation

Effect of Liquid Droplets on Turbulence Structure in a Round Gaseous Jet

A second-order model which predicts the modulation of turbulence in jets laden with uniform size solid particles or liquid droplets is discussed. The approach followed is to start from the separate momentum and continuity equations of each phase and derive two new conservation equations. The first is for the carrier fluid's kinetic energy of turbulence and the second for the dissipation rate of that energy. Closure of the set of transport equations is achieved by modeling the turbulence correlations up to a third order. The coefficients (or constants) appearing in the modeled equations are then evaluated by comparing the predictions with LDA-measurements obtained recently in a turbulent jet laden with 200 microns solid particles. This set of constants is then used to predict the same jet flow but laden with 50 microns solid particles. The agreement with the measurement in this case is very good

Effect of liquid droplets on turbulence in a round gaseous jet

The main objective of this investigation is to develop a two-equation turbulence model for dilute vaporizing sprays or in general for dispersed two-phase flows including the effects of phase changes. The model that accounts for the interaction between the two phases is based on rigorously derived equations for turbulence kinetic energy (K) and its dissipation rate epsilon of the carrier phase using the momentum equation of that phase. Closure is achieved by modeling the turbulent correlations, up to third order, in the equations of the mean motion, concentration of the vapor in the carrier phase, and the kinetic energy of turbulence and its dissipation rate for the carrier phase. The governing equations are presented in both the exact and the modeled formes. The governing equations are solved numerically using a finite-difference procedure to test the presented model for the flow of a turbulent axisymmetric gaseous jet laden with either evaporating liquid droplets or solid particles. The predictions include the distribution of the mean velocity, volume fractions of the different phases, concentration of the evaporated material in the carrier phase, turbulence intensity and shear stress of the carrier phase, droplet diameter distribution, and the jet spreading rate. The predictions are in good agreement with the experimental data

Echocardiographic variables associated with mitral regurgitation after aortic valve replacement for aortic valve stenosis

AbstractBackgroundMitral regurgitation (MR) is frequently associated with aortic stenosis. Previous reports have shown that coexisting mitral insufficiency can regress after aortic valve replacement (AVR) while others recommend dealing with examination.AimThe study aimed to assess the severity of MR before and after aortic valve replacement for aortic stenosis and to define the determinants of its postoperative evolution.MethodsFor this purpose, 30 adult patients referred for aortic valve surgery underwent pre- and 1month postoperative transthoracic echocardiography including 2D, MM, PW, CW and color Doppler examination.ResultsPostoperative MR improved in 68.4% of the 19 patients (63.3%) who had preoperative moderate MR (p=0.002). The effect of the valve size on the postoperative MR was statistically insignificant (0.059) but was significant on regression of the mass (p=0.001) and drop in mean PG (p=0.04) across AV. Patients with persistent moderate MR after surgery were all in AF and had significantly larger left atrial size (45±26mm), compared to none and a smaller left atrial (37±19mm) in patients in whom MR regressed or disappeared after surgery; respectively, p<0.05. The postoperative variables associated with moderate MR were peak PG across AV (29.4±5.1 vs 38.0±5.7 p=0.004), mean PG (15.04±4.4 vs 22.8±5.8 p=0.009) and LVMI (124.7±19.3 vs 147.2±31.6 p=0.065).ConclusionPreoperative predictors of residual postoperative MR were large LA and AF while the postoperative variables were high peak and mean pressure gradient across the aortic valve and high LVMI

A nonlinear problem having a continuous locus of singular points and no multiple solutions

AbstractThe boundary-value problem ϵz″ = (z2 − t2)z′, ϵ > 0, z(− 1) = α, z(0) = β, t ϵ [−1, 0], has been shown to have a solution, and moreover, depending on the choice of α and β, multiple solutions to it exist. We consider the more general equation f(z, t)z″ = (zr − ts)z′ for a particular non-negative function f(z, t), and integrate the equation exactly. Depending on α and β, we find that either there are no solutions, or that only unique solutions exist. The conclusion is that the presence of a continuous locus of singular points, given by zr = ts, does not necessarily produce multiple solutions

Bulletproof Vests/shields Prepared From Composite Material Based On Strong Polyamide Fibers And Epoxy Resin

Fiber Reinforced Plastics (FRP) have arisen as a main class of tactual materials having high strength and light weight implemented in a large scale of different applications. This study performs a comparison between the enhanced propidines of Kevlar 49 fiber and Twaron CT 704 reinforced with epoxy resin to obtain an efficient, light weight and slim body m o r capable of resisting high speed projectiles (9 mm bullets). Reinforcing the fabrics adds extra strength to the fabrics instead of using several unreinforced fabrics which increases the weight thickness and the cost of the final product. The response of the prepared composite material based on the two different fibers was studied by using a test barrel for the penetration test. In addition. indentation test is also au lied to compare between the mechanical properties of both laminates and determine which fabric is better for life protection application. The final results showed that using the technique of reinforcing the fabrics specially Twaron is much better where the final bulletproof shield has a smaller number of layers and was found lighter by 40% than those made by Kevlar

Diagnostic inflammatory markers for bronchial asthma

Egypt J Pediatr Allergy Immunol 2005; 3(1): 2-