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The selection of appropriate monitoring methods is necessary to realize the early warning of slope stability. In this study, a new monitoring method was proposed on the basis of bolt stress variation with reduction factors. Numerical simulation was conducted to construct a rock slope model with joint, and the monitoring bolt was placed at the joint. The relationship between bolt axial force and slope stability was investigated. Moreover, the position and inclination of the bolt were investigated thoroughly. A comprehensive comparison was conducted using an existing displacement monitoring method. Results show that (1) a single peak distribution of the bolt axial force occurs along the length, and the peak appears at the location of the joint and bolt intersection with bolt axial force saltation, which is considered the optimal axial force monitoring position. (2) Regardless of the bolt inclination, the axial force saltation constantly exists, and the internal slope stress can be monitored, except when the angle is 90°. (3) The bolt position does not influence the monitoring effects provided that the bolt penetrates the joint. (4) The axial force saltation of the bolt is earlier than the displacement saltation of the slope; this phenomenon can achieve remarkable monitoring effects appropriately for slope stability early warning.

Identifying stops from GPS trajectories is one of the main concerns in the study of moving objects and has a major effect on a wide variety of location-based services and applications. Although the spatial and non-spatial characteristics of trajectories have been widely investigated for the identification of stops, few studies have concentrated on the impacts of the contextual features, which are also connected to the road network and nearby Points of Interest (POIs). In order to obtain more precise stop information from moving objects, this paper proposes and implements a novel approach that represents a spatio-temproal dynamics relationship between stopping behaviors and geospatial elements to detect stops. The relationship between the candidate stops based on the standard time&ndash, distance threshold approach and the surrounding environmental elements are integrated in a complex way (the mobility context cube) to extract stop features and precisely derive stops using the classifier classification. The methodology presented is designed to reduce the error rate of detection of stops in the work of trajectory data mining. It turns out that 26 features can contribute to recognizing stop behaviors from trajectory data. Additionally, experiments on a real-world trajectory dataset further demonstrate the effectiveness of the proposed approach in improving the accuracy of identifying stops from trajectories.

To organize trajectory data is a challenging issue for both studies on spatial databases and spatial data mining in the last decade, especially where there is semantic information involved. The high-level semantic features of trajectory data exploit human movement interrelated with geographic context, which is becoming increasingly important in representing and analyzing actual information contained in movements and further processing. This paper argues for a novel semantic trajectory model named TOST. It considers both semantic and geographic information of trajectory data happens along network infrastructure simultaneously. In TOST, a flexible intersection-based semantic representation is designed to express movement typically constrained by urban road networks by combining sets of local semantic details along the time axis. A relational schema based on this model was instantiated against real datasets, which illustrated the effectivity of our proposed model.

To evaluate the effects of age and pulmonary hypertension on phasic right atrial function we measured right atrial volumes at 3 different points in the cardiac cycle in 57 healthy subjects and 33 patients with pulmonary arterial hypertension. Right atrial reservoir function was assessed by systolic filling volume and passive and active emptying by passive and active emptying volume and fraction of total emptying. We compared these phases of right atrial function in 30 healthy subjects

Paravalvular jets, documented by intraoperative transesophageal echocardiography, have prompted immediate valve explantation by others, yet the significance of these jets is unknown.Twenty-seven patients had intraoperative transesophageal two-dimensional color Doppler echocardiography, performed to assess the number and area of regurgitant jets after valve replacement, before and after protamine. Patients were grouped by first time versus redo operation, valve position and type.Before protamine, 55 jets were identified (2.04+/-1.4 per patient) versus 29 jets after (1.07+/-1.2 per patient, p = 0.0002). Total jet area improved from 2.0+/-2.2 cm2 to 0.86+/-1.7 cm2 with protamine (p0.0001). In all patients jet area decreased (average decrease, 70.7%+/-27.0%). First time and redo operations had similar improvements in jet number and area (both p0.6). Furthermore, mitral and mechanical valves each had more jets and overall greater jet area when compared to aortic and tissue valves, respectively.Following valve replacement, multiple jets are detected by intraoperative transesophageal echocardiography. They are more common and larger in the mitral position and with mechanical valves. Improvement occurs with reversal of anticoagulation.

We assessed the effects of implantation of Myosplint (Myocor, Maple Grove, Minn), a device that changes left ventricular (LV) cross-sectional shape from circular to bilobar, on regional LV function. A total of 10 open-chest dogs with tachycardia-induced cardiomyopathy were studied before and after Myosplint implantation. LV cross-sectional epicardial echocardiography at the papillary muscle level was performed along with acquisition of hemodynamic data. LV normalized thickening, fractional thickening, end-diastolic thickness, and end-diastolic curvatures were calculated for 10 LV segments. Myosplint implantation did not affect LV hemodynamics, but decreased average end-diastolic curvature (P.0001) and increased its segmental heterogeneity (P.0001). There was no change in average fractional thickening, whereas normalized thickening increased (P =.05). In contrast, segmental heterogeneity of both normalized and fractional thickening increased (P =.02 and P =.01, respectively). Structural modeling confirmed that Myosplint implantation increases regional stress heterogeneity and curvature heterogeneity. LV cross-sectional shape markedly affects regional LV performance.

A 22-year-old man who had hypertrophic cardiomyopathy and progressive exertional dyspnea despite treatment with β-blockers was referred for septal myectomy. Preoperative transthoracic echocardiography showed severe asymmetric septal hypertrophy (septal thickness of 3.1 cm) with marked systolic anterior motion of the mitral valve and a dynamic left ventricular outflow tract (LVOT) gradient of 125 mm Hg. Epicardial real-time 3-dimensional echocardiography (RT3DE) (Sonos 7500, Philips Medical Systems), was performed intraoperatively, providing …

Using real-time, three-dimensional (3D) color Doppler, experimental studies were performed to quantify velocity in the out flow tract from cross-sectional, short axis images. In vitro experiments showed an excellent linear correlation between the reference pulsed wave (PW) Doppler and 3D color estimates of the peak velocities (r=0.98). In an animal experiment 3D peak flow velocities showed a reasonably good agreement with reference peak velocities by PW Doppler (r=0.76, delta =+11.6%). The spatial mean velocity by 3D showed a good linear relationship with PW peak velocity, but with an anticipated underestimation (r=0.81, delta=-43 %) due to the non-uniform velocity profile. Real-time, color 3D echocardiography was capable of quantifying velocities accurately, permitting the calculation of flow volume without any geometrical assumptions about flow distribution.

Recently, 3D echocardiography (3DE) has developed the capability to capture 3D images in real-time and has been reported to be accurate for estimating left ventricular (LV) volume. The authors hypothesized that real-time 3DE could determine LV stroke volumes (SV) more accurately than conventional 2DE. The aim of this study was to compare 2DE and 3DE for estimating LV stroke volumes during a variety of hemodynamic conditions, including left anterior descending (LAD) coronary artery occlusions. During a total of 30 hemodynamic conditions in 6 sheep with chronic aortic regurgitation, electromagnetic (EM) flow probes and meters were used to obtain LV SV. LV end-diastolic (LV EDV) and LV end-systolic volumes (LV ESV) were measured using real-time; 3DE with Simpson's rule (slice spacing 7 mm). For 24 conditions without LAD occlusions, SV by EM ranged from 27 to 66 ml (average 45/spl plusmn/10 ml). The correlation for LV SV measured by 3DE and that by EM was excellent (r=0.92, y=0.91x+3.6, /spl Delta/=-1/spl plusmn/4 ml, n=24), and better than that between 2DE and EM (r=0.62, y=0.68x+8.8, /spl Delta/=-5.6/spl plusmn/9.4 ml, p=0.0003). For 6 conditions during LAD occlusion, SV by EM ranged from 26 to 58 ml (average 41/spl plusmn/12 ml). SV derived from 3DE also agreed well with values derived by EM (r=0.96); however, the r-value between 2DE and EM was reduced to 0.58. It is concluded that real-time 3DE provided accurate assessment of LV SV under both ischemic and nonischemic conditions, while conventional 2DE showed poor correlations with reference standards, especially for SVs during coronary artery occlusion.

An efficient compression strategy is indispensable for digital echocardiography. Previous work has suggested improved results utilizing wavelet transforms in the compression of 2D echocardiographic images. Set partitioning in hierarchical trees (SPIHT) was modified to compress echocardiographic scan-line data based on the wavelet packet transform. A compression ratio of at least 94:1 resulted in preserved image quality.

Real-time, 3D color Doppler echocardiography (RT3D) is capable of quantifying flow at the LV outflow tract (LVOT). However, previous works have found significant underestimation for flow rate estimation due to finite scanning time (ST) of the color Doppler. The authors have, therefore, developed a mathematical model to correct the impact of ST on flow quantification and validated it by an animal study. Scanning time to cover the entire cross-sectional image of the LVOT was calculated as 60 ms, and the underestimation due to temporal averaging effect was predicted as 18/spl plusmn/7%. In the animal experiment, peak flow rates were obtained by spatially integrating the velocity data front the cross-sectional color images of the LVOT. By applying a correction factor, there was an excellent agreement between reference flow rate by an electromagnetic flow meter and RT3D (A/spl uml/=-5.6 ml/s, r=0.93), which was significantly better than without correction (p

To evaluate the load dependence of effective regurgitant orifice area (ROA) in an animal model of chronic aortic regurgitation.Eight sheep were studied 10-20 weeks after the surgical creation of aortic regurgitation. After baseline studies, 500 ml of blood, angiotensin II, and nitroprusside were infused sequentially. Electromagnetic flow meters were used as reference standards to determine aortic regurgitation volume. The time-velocity integral was acquired using the continuous wave Doppler method.Baseline aortic regurgitant volume varied from 8 ml (regurgitant fraction 28%) to 29 ml (59%), with a mean (SD) value of 17 (8) ml; mean ROA was 0.15 (0.05) cm2. During angiotensin II infusion, aortic regurgitation volume (20 (8) ml) and mean diastolic aortoventricular pressure gradient (62 (18) mm Hg) increased by 26 (16)% and 48 (64)%, respectively (p0.01 for both). ROA did not change (0.16 (0.06) cm(2), p = 0.15). During nitroprusside infusion, aortic regurgitant volume (13 (7) ml, p = 0.05) and diastolic pressure gradient (25 (13) mm Hg, p0.05) decreased. ROA did not change (0.15 (0.05) cm2). When analysing 32 stages together, aortic regurgitant volume (r = 0.78, p0.01) and regurgitant fraction (r = 0.55, p0.01) correlated well with ROA. However, diastolic pressure gradient (r = 0.28) was not significantly correlated with ROA.In an animal model of chronic aortic regurgitation, ROA did not change with load alterations.

AIM: The aim of this study was to investigate the feasibility and accuracy of using symmetrically rotated apical long axis planes for the determination of left ventricular (LV) volumes with real-time three-dimensional echocardiography (3DE). METHODS AND RESULTS: Real-time 3DE was performed in six sheep during 24 haemodynamic conditions with electromagnetic flow measurements (EM), and in 29 patients with magnetic resonance imaging measurements (MRI). LV volumes were calculated by Simpson's rule with five 3DE methods (i.e. apical biplane, four-plane, six-plane, nine-plane (in which the angle between each long axis plane was 90 degrees, 45 degrees, 30 degrees or 20 degrees, respectively) and standard short axis views (SAX)). Real-time 3DE correlated well with EM for LV stroke volumes in animals (r=0.68-0.95) and with MRI for absolute volumes in patients (r-values=0.93-0.98). However, agreement between MRI and apical nine-plane, six-plane, and SAX methods in patients was better than those with apical four-plane and bi-plane methods (mean difference = -15, -18, -13, vs. -31 and -48 ml for end-diastolic volume, respectively, P

Background . The Cosgrove-Edwards Annuloplasty System includes a universally flexible band that corrects mitral annular dilatation via measured plication of the posterior annulus. The purpose of this study was to evaluate midterm clinical and functional results in the first 197 patients receiving this flexible annuloplasty band at mitral valve repair. Methods . From February 1993 to July 1994, 197 consecutive patients with mitral regurgitation had mitral valve repair using this system. Valve disease was degenerative in 73%, rheumatic in 15%, ischemic in 5%, infectious in 2.5%, and other in 4%. Results . Immediately after repair, echocardiographic mitral regurgitation was none or trivial in 92%, 1+ in 5%, and 2+ in 3%. There were no hospital deaths. Late follow-up was available in 195 patients (99%), with 661 patient-years of follow-up available for analysis. Four-year actuarial survival was 93%, freedom from thromboembolism 94%, from endocarditis 98%, and from reoperation 95%. At a mean interval of 18 months, echocardiography in 157 patients demonstrated no or trace mitral regurgitation in 56%, 1+ in 24%, 2+ in 9%, 3+ in 6%, and 4+ in 3%. At a mean of 61 ± 5 months, reconstruction of the mitral annulus from real-time three-dimensional echocardiographic images in 10 patients confirmed preserved nonplanar shape and sphincter mechanism of the mitral annulus. Annular orifice area decreased 28% ± 11% during the cardiac cycle from a mean of 10.1 ± 3.9 cm 2 in diastole to 7.2 ± 2.8 cm 2 in systole. Conclusions . This annuloplasty system is effective for repair of mitral regurgitation secondary to all causes and preserves mitral annular flexibility and function at 5-year follow-up.