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The properties of artificially grown thin films are strongly affected by surface processes during growth. Coherent X-rays provide an approach to better understand such processes and fluctuations far from equilibrium. Here we report results for vacuum deposition of C$_{60}$ on a graphene-coated surface investigated with X-ray Photon Correlation Spectroscopy in surface-sensitive conditions. Step-flow is observed through measurement of the step-edge velocity in the late stages of growth after crystalline mounds have formed. We show that the step-edge velocity is coupled to the terrace length, and that there is a variation in the velocity from larger step spacing at the center of crystalline mounds to closely-spaced, more slowly propagating steps at their edges. The results extend theories of surface growth, since the behavior is consistent with surface evolution driven by processes that include surface diffusion, the motion of step-edges, and attachment at step edges with significant step-edge barriers., Comment: 14 pages and 7 figures

Aim: To detect and quantify early subtle left ventricular (LV) systolic dysfunction using Tissue Doppler Imaging in type 2 diabetic patients with apparently normal LV ejection fraction. Methods: Ninety age and sex matched subjects were enrolled in the study, sixty of them were suffering from type 2 diabetes mellitus (DM) whom were divided according to HbAlc into 2 groups, 30 uncontrolled diabetic patients with HbAlc > 8% and 30 controlled diabetic patients with HbAlc

We propose a method to evaluate public transport network vulnerability. We study the evolution of the passenger Volume Over Capacity (VOC) ratio throughout the network to measure the spatial and temporal extent of the impacts caused by an unplanned service segment disruption. The VOC ratio provides an indication of the on-board travel comfort, an important level-of-service indicator, as well as reflects the residual capacity for absorbing additional demand. Because of the dynamic nature of public transport systems, disturbances propagate through the network in both time and space. Our modelling approach is able to capture transit system dynamics and quantify the extent to which the network exhibits spillover effects. We apply the method to the case of the rapid public transport system of Stockholm Sweden We demonstrate how the changes in network saturation and the corresponding recovery time can be quantified.

We present observations of Io's Loki Patera taken with the 10-m Keck telescopes between 1998 and 2016. Adding these data to those published by Rathbun and Spencer (2006) and the Gemini data of de Kleer and de Pater (2016a, 2017) results in a database of 3.5–3.8 µm emission from Loki Patera over almost 3 decades. Data presented here contain adaptive optics (AO) observations of Io's sunlit hemisphere at wavelengths between 1.6 and 5 µm, AO observations of Io in eclipse at 2–5 µm, and non-AO observations of Io in eclipse at 1.6–12 µm. The non-AO data were taken in September of 1999, during the early phase of a brightening event that was documented by Howell et al. (2001). Dual-component Io Flow model (IFM) fits to our 1999 observations show a mostly cool lava crust over almost the entire patera floor, with a relatively small hotter component making up less than 1% of the total area, consistent with previous observations. The 30-year timeline of Loki Patera revealed that, after an apparent cessation of, or change in, brightening events in 2002, Loki Patera became active again in 2009. The more recent activity may have a slightly shorter periodicity than observed by Rathbun et al. (2002), and the direction of flow propagation appears to have reversed. Since 2009 the flow direction is in the clockwise direction, starting in the north or north-east corner and propagating along the patera towards the south-west. During the Galileo era the propagation was in the counter-clockwise direction, starting in the south-west and propagating towards the east. Both the 30-year timeline and the 1.6–12 µm spectrum that was obtained during the brightening event in 1999 agree well with Matson et al.’s (2006) overturning lava lake model, as modified by de Kleer and de Pater (2017).

We consider dynamic equilibria for flows over time under the fluid queuing model. In this model, queues on the links of a network take care of flow propagation. Flow enters the network at a single source and leaves at a single sink. In a dynamic equilibrium, every infinitesimally small flow particle reaches the sink as early as possible given the pattern of the rest of the flow. Although this model has been examined for many decades, progress has been relatively recent. In particular, the derivatives of dynamic equilibria have been characterized as thin flows with resetting, which allows for more structural results. Our two main results are based on the formulation of thin flows with resetting as a linear complementarity problem and its analysis. We present a constructive proof of existence for dynamic equilibria if the inflow rate is right-monotone. The complexity of computing thin flows with resetting, which occurs as a subproblem in this method, is still open. We settle it for the class of two-terminal, series-parallel networks by giving a recursive algorithm that solves the problem for all flow values simultaneously in polynomial time.

This paper presents a two-dimensional experimental study of the interaction of wet dam-break bores with a fixed structure, regarding the evolution of the incident flows and the resultant green water events on the deck. The study employs image-based techniques to analyse flow propagation from videos taken by high-speed cameras, considering five different shipping water cases. The features of small air-cavities formed in some green water events of the plunging-dam-break type were analysed. Then, the spatial and temporal distribution of water elevations of the incident bores and green water were investigated, providing a database to be used for model validations. Some guidelines for the selection of the freeboard exceedance, which is of relevance for green water simulations, were provided. Finally, the relationship between the incident bore and water-on-deck kinematics was discussed. The proposed study can be used as a reference for performing simplified and systematic analyses of green water in a different two-dimensional setup, giving high-resolution data that visually capture the flow patterns and allow model validations to be performed.

We propose a method to evaluate public transport network vulnerability. We study the evolution of the passenger Volume Over Capacity (VOC) ratio throughout the network to measure the spatial and temporal extent of the impacts caused by an unplanned service segment disruption. The VOC ratio provides an indication of the on-board travel comfort, an important level-of-service indicator, as well as reflects the residual capacity for absorbing additional demand. Because of the dynamic nature of public transport systems, disturbances propagate through the network in both time and space. Our modelling approach is able to capture transit system dynamics and quantify the extent to which the network exhibits spillover effects. We apply the method to the case of the rapid public transport system of Stockholm Sweden We demonstrate how the changes in network saturation and the corresponding recovery time can be quantified.

The Jet Transport method has emerged as a powerful tool for the numerical integration of ordinary differential equations; it uses polynomial expansions to approximate the flow map associated to the differential equation in the neighbourhood of a reference solution. One of the main drawbacks of the method is that the region of accuracy becomes smaller along the integration. In this paper we introduce a procedure to determine a ball covering the set of given initial conditions that keeps the accuracy of the integration within a selected threshold. The paper gives detailed explanations of the algorithm illustrated with some examples of applicability, as well as a comparison with a previous existing method for the same purpose

Taking time-varying parking demands and supplies into account, this paper develops a dynamic parking choice model to simulate drivers’ searching for parking spaces between parking lots. In this study, each parking lot has one access passage and vehicles can move or wait for entering the park in the access passage. The flow propagation formula in the access passage of parking lots is established to obtain the number of vehicles entering the parking lot from the access passage within each time interval. This paper brings forward the instantaneous dynamic user-optimal condition of dynamic parking choice, constructs an equivalent variational inequality (VI) model and develops a diagonalization algorithm to solve the model. A numerical example demonstrates the rate of in-flow, the rate of out-flow, link flow, instantaneous travel time on each link or access passage of the parking lot, and the amount and routes of cruising traffic at each time point.

This study aims to investigate the measurement of left ventricular flow propagation velocity, V p, using phase contrast magnetic resonance imaging and to assess the discrepancies resulting from inflow jet direction and individual left ventricular size. Three V p measuring techniques, namely non-adaptive (NA), adaptive positions (AP) and adaptive vectors (AV) method, were suggested and compared. We performed the comparison on nine healthy volunteers and nine post-infarct patients at four measurement positions, respectively, at one-third, one-half, two-thirds and the conventional 4 cm distances from the mitral valve leaflet into the left ventricle. We found that the V p measurement was affected by both the inflow jet direction and measurement positions. Both NA and AP methods overestimated V p, especially in dilated left ventricles, while the AV method showed the strongest correlation with the isovolumic relaxation myocardial strain rate (r = 0.53, p

Floods are frequent and widespread in Italy and pose a severe risk for the population. Local administrations commonly use flow propagation models to delineate the flood prone areas. These modeling approaches require a detail geo-environmental data knowledge, intensive calculation and long computational times. Conversely, statistical methods can be used to asses flood hazard over large areas, or to extend the flood hazard zonation to the portion of the river networks where hydraulic models have still not been applied or can be applied with difficulties. In this paper, we describe a statistical approach to prepare flood hazard maps for the whole of Italy. The proposed method is based on a multivariate machine learning algorithm calibrated using in input flood hazard maps delineated by the local authorities and terrain elevation data. The preliminary results obtained in several major Italian catchments indicate good performances of the statistical algorithm in matching the training data. Results are promising giving the possibility to obtain reliable delineations of flood prone areas obtained in the rest of the Italian territory.

Mitral regurgitation (MR) can affect left ventricular diastolic parameters because of interference with regurgitation flow. This study compared left ventricular diastolic parameters between patients with and without significant MR. The MR group included 57 consecutive patients with significant MR. Fifty-seven age-, sex- and Tei index-matched patients without significant MR were selected as the reference group. Baseline characteristics and Tei index and its components were comparable between the MR and reference groups. The MR group had higher left atrial volume index, transmitral E wave velocity (E), ratio of E to transmitral A wave velocity, early diastolic mitral annular velocity (Ea), E/Ea, and ratio of E to isovolumic relaxation flow propagation velocity (IRFPV) (p ≤ 0.025), and lower E-wave deceleration time (p = 0.019) and late diastolic mitral annular velocity (p < 0.001). However, the two groups had similar IRFPV (p = 0.844). In conclusion, MR apparently affects E and Ea, but not IRFPV. IRFPV could potentially be a reliable relaxation parameter in patients with significant MR, but further confirmation by invasive studies is needed.

Arterial stiffness is increasingly recognized as an important determinant of cardiovascular risk and may be directly involved in the process of atherosclerosis. As atherosclerosis leads to increased arterial resistance and decrease the flow propagation speed within the arterial lumen, a similar decrease in aortic flow propagation with increased downstream resistance is detected, so aortic flow propagation velocity AVP was evaluated in many studies as a new parameter of aortic stiffness. Aim: To measure arterial stiffness using the new parameter AVP and compare it to flow mediated dilatation FMD as a parameter of endothelial dysfunction in patients with metabolic syndrome MS. Methods: AVP (assessed by transthoracic echocardiography) and FMD (assessed by brachial artery reactivity test) were measured in 100 patients with MS (Group 1) and were compared to 14 normal subjects (Group 2). Results: Patients with MS had significantly lower values of AVP as compared to the normal subjects; 36 ± 5 cm/s vs 57 ± 5, p

In this article, we propose a framework for travel time prediction based on a time-discrete, mesoscopic traffic flow model, in which the measure of travel time is obtained as a link performance resulting from a dynamic network loading process. The spatiotemporal flow propagation on the road network is simulated incorporating the mesoscopic model and a linear link performance model, based on a travel time function. Acceleration levels are calculated explicitly, as a result of a fixed point problem. The traffic assignment to the network has been carried out through a completely new model, based on the Bee Colony Optimization (BCO) metaheuristics. In comparison with results of simulations carried out by using another mesoscopic model (DYNASMART), the travel times obtained with the proposed method appear more realistic. (C) 2015 Elsevier Ltd. All rights reserved.

Chronic exercise induces physiological enlargement of the left ventricle (‘athlete's heart’), but the effects of current and long-term exercise training on diastolic function have not been investigated. Echocardiography and Doppler imaging were used to assess left ventricular (LV) dimensions and indices of diastolic filling in 22 elite athletes at the end of their ‘off-season’ (baseline) and, subsequently, following 3 and 6 months of training. Twelve matched controls were also studied at baseline, 3 and 6 months. Compared to controls at baseline, athletes exhibited significantly higher LV mass (235.7 ± 7.1 g versus 178.1 ± 14.5 g, P < 0.01) and reduced flow propagation velocity (VP: 50.21 ± 1.7 versus 72.2 ± 3.6 cm s−1, P < 0.01), a measure of diastolic function. Three months of training further increased LV mass in athletes (253.2 ± 7.1 g; P < 0.01 versus baseline), and significantly increased their VP (66.7 ± 2.5 cm s−1; P < 0.05 versus baseline). These trends for increased mass and diastolic filling persisted following 6 months of training (LV mass 249.0 ± 8.7 g P < 0.05 versus baseline; VP 75.7 ± 3.0 cm s−1; P < 0.01 versus baseline, and P= 0.01 versus 3 months). This study suggests that following a period of relative inactivity the rate of ventricular relaxation during early diastole may be slowed in athletes who exhibit ventricular hypertrophy, whilst resumption of training increases the speed of ventricular relaxation in the presence of further hypertrophy of the left ventricle.

Pulsed wave tissue Doppler echocardiography (PW-TDE) and color M-mode are new Doppler methods for left ventricular (LV) diastolic function assessment. To date, few studies have compared the data obtained by these methods in the same series of patients and compared them to the current clinical reference method of detecting LV diastolic function.To determine the utility of PW-TDE and color M-mode parameters in the assessment of LV diastolic function in the typical patient population encountered in daily clinical practice and to compare their discriminating power.Early diastolic septal mitral annular velocity (Em) determined by PW-TDE and color M-mode flow propagation velocity (Vp) were measured in 86 male patients and compared to LV filling patterns obtained using standard Doppler indices. Values of Em0.08 m s(-1) and Vp0.5 m s(-1) were considered as markers of abnormal LV diastolic function.A value of Em0.08 m s(-1) distinguished mild to moderate LV diastolic dysfunction with higher sensitivity and specificity than Vp0.5 m s(-1) (96% and 87% vs. 73% and 84%, respectively). A comparison of receiver operating characteristic curves showed a significant difference for areas under the curve in favor of Em (P0.01). In a stepwise multiple logistic regression analysis, a pseudonormal filling pattern and an EF60% were identified as significant predictors of Vp false negative results (p0.05).Em appears to be superior to Vp in the detection of mild to moderate LV diastolic dysfunction. Vp failed to detect abnormal LV diastolic function in particular in patients with preserved LV systolic function and a pseudonormal filling pattern type.

Blood flow throughout the cardiovascular system is governed by the Navier-Stokes equations, a set of 4 coupled 4-dimensional (3 of space and 1 of time) partial differential equations. Although these are impossibly complex to solve analytically or even with the most powerful supercomputers, there are

Background — Accurate determination of pulmonary vascular resistance (PVR) is an important component in the evaluation and treatment of pediatric patients with pulmonary hypertension. We developed a novel technique, based on the concept of flow propagation, to estimate PVR noninvasively. The hypothesis is that changes in PVR cause changes in the velocity propagation (Vel prop ) within the main pulmonary artery and that Vel prop can be quantified using color M-mode imaging. Methods and Results — We tested the hypothesis using mathematical modeling, in vitro experiments, and preliminary clinical studies. The mathematical model showed that pressure and velocity tracings are closely correlated in time and that 6 to 18 ms time resolution was needed to resolve propagation times within typical main pulmonary artery lengths (2 to 5 cm). The in vitro experiments demonstrated that it was feasible to use color M-mode to measure Vel prop and that Vel prop correlated well with downstream resistance [y=(−1.01x)+22.77; R =0.96]. The method was then evaluated on patients undergoing acute pulmonary reactivity testing (n=22 measurements). Good correlation between Vel prop and PVR was found [y=(−1.71x)+26.0; R =0.90; SEE=2.41]. Conclusion — This newly developed method promises to be useful in the noninvasive evaluation of adults and children with pulmonary hypertension.

Energy distributions of high frequency linear wave fields are often modelled in terms of flow or transport equations with ray dynamics given by a Hamiltonian vector field in phase space. Applications arise in underwater and room acoustics, vibro-acoustics, seismology, electromagnetics, and quantum mechanics. Related flow problems based on general conservation laws are used, for example, in weather forecasting or molecular dynamics simulations. Solutions to these flow equations are often large scale, complex and high-dimensional, leading to formidable challenges for numerical approximation methods. This paper presents an efficient and widely applicable method, called discrete flow mapping, for solving such problems on triangulated surfaces. An application in structural dynamics - determining the vibro-acoustic response of a cast aluminium car body component - is presented., Comment: 12 pages, 6 figures

Aims: Early diastolic mitral annular velocity (e') obtained by tissue Doppler imaging (TDI) is widely used to evaluate left ventricular (LV) diastolic function based on the assumption that it reflects myocardial relaxation in the long-axis direction. In this study, we aimed to determine whether or not e' truly reflects early diastolic longitudinal myocardial relaxation, and which is the most useful for evaluating LV diastolic function among e' measured at the interventricular-septal annulus (IS-e'), that measured at the lateral annulus (LW-e') or their mean value (M-e'). Methods and results: IS-e', LW-e', and M-e' were measured using colour TDI in 15 patients with hypertrophic cardiomyopathy, 13 patients with hypertension and 19 control subjects. Using two-dimensional speckle tracking imaging, early diastolic myocardial strain rates (SR_[E]) were measured for the IS (IS-SR_[E]), LW(LW-SR_[E]) and entire LV myocardium (G-SR_[E]). IS-e' was excellently correlated with IS-SR_[E] (r = 0.90, P < 0.001); the correlation was better than that between LW-e' and LW-SR_[E] (r = 0.75, P < 0.001). IS-e' and M-e' were well correlated with G-SR_[E] (r = 0.88, P < 0.001 and r = 0.86, P < 0.001, respectively) and with LV early diastolic flow propagation velocity (r = 0.77, P < 0.001 and r = 0.78, P < 0.001, respectively). The correlations of LW-e' to G-SR_[E] (r = 0.80, P < 0.001) and flow propagation velocity (r = 0.75, P < 0.001) did not reach this level. Conclusion: IS-e' well reflected LV longitudinal myocardial relaxation and LV diastolic function, and was found to be more useful in evaluating LV diastolic function than LW-e'.

Flow propagation refers to the delay in the onset of blood flow during early filling at more apical ventricular locations. The velocity of flow propagation (Vp) into the left ventricle (LV) provides a preload insensitive estimate of LV relaxation, confirmed invasively by a strong negative correlation with the relaxation time constant (tau) [1, 2]. Clinically, Vp < 50 ms is commonly taken as evidence of abnormal diastolic function. No direct physical relationship between muscle relaxation and flow propagation has been previously illustrated. By simultaneous measurement of myocardial mechanics (radial expansion) and blood patterns throughout the LV and during early filling we expect to illustrate a correlated spatial and temporal relationship between the mechanics which drive blood flow and the resulting blood flow patterns.

Cell signaling pathways are sequences of biochemical reactions that propagate an input signal, such as a hormone binding to a cell-surface receptor, into the cell to trigger a reactive process. Assessment of pathway activities is crucial for determining which pathways play roles in disease versus normal conditions. To date various pathway flow/perturbation assessment tools are available, however they are constrained to specific algorithms and specific data types. There are no accepted standards for evaluation of pathway activities or simulation of flow propagation events in pathways, and the results of different software are difficult to compare. Here we present Pathway Signal Flow Calculator (PSFC), a Cytoscape app for calculation of a pathway signal flow based on the pathway topology and node input data. The app provides a rich framework for customization of different signal flow algorithms to allow users to apply various approaches within a single computational framework.

A multicode approach, based on the simultaneous use of zero-dimensional, one-dimensional, and three-dimensional models, has been developed and tested, and is here applied to predict the thermodynamic and fluid dynamic phenomena that characterize the unsteady gas flow propagation along the exhaust system of a turbocharged four-cylinder engine. The investigation is carried out by applying each model in a different region of the geometry, allowing to obtain detailed information of the flow behavior in complex elements, such as junctions, avoiding the significant limitations that a one-dimensional scheme always introduces, as well as fast processing typical of one-dimensional and zero-dimensional models, devoted to the analysis of ducts and volumes. The effect of the influence of different configurations of the exhaust system on the engine performance is analyzed.

A magnetic resonance imaging projective velocity encoding sequence was used to determine the pulse-wave velocity in an artery model. To this end, a well-defined flow phantom simulating flow propagation in large arteries was used. In order to validate the measurement method in the presence of large reflected waves, these were deliberately created in the phantom. The projective sequence was applied to two measurement sites and the wave velocity was determined from the spatial and temporal separations of the foot of the velocity waveform. A theoretical model describing reflection and attenuation phenomena was compared with experimental velocity waveforms. The model showed that reflections and attenuation can explain the important changes in velocity waveforms. The model also confirmed that in the presence of reflecting waves, the foot of the waveform can be used as a characteristic point for measurements through changes in the waveform. J. Magn. Reson. Imaging 2001;14:120–127. © 2001 Wiley-Liss, Inc.

OBJECTIVES: We sought to assess the prognostic value of left ventricular (LV) filling patterns, as determined by mitral E-wave deceleration time (DT) and color M-mode flow propagation velocity (Vp), on cardiac death and serial changes in LV volumes after a first myocardial infarction (MI).BACKGROUND: Combined assessment of DT and Vp allows separation of the effects of compliance and relaxation on LV filling, thereby allowing identification of pseudonormal filling. This may be valuable after MI, where abnormal LV filling is frequently present.METHODS: Echocardiography was performed within 24 h, five days and one and three months after MI in 125 unselected consecutive patients. Normal filling was defined as DT 140 to 240 ms and Vp > or =45 cm/s; impaired relaxation as DT > or =240 ms; pseudonormal filling as DT 140 to 240 ms and Vp RESULTS: Left ventricular filling was normal in 38 patients; impaired relaxation in 38; pseudonormal in 23; and restrictive in 26. End-systolic and end-diastolic volume indexes were significantly increased during the first three months after MI in patients with pseudonormal or restrictive filling (37+/-15 vs. 47+/-19 ml/m2, p or =II (p = 0.008) independently predicted cardiac death, compared with clinical and echocardiographic variables.CONCLUSIONS: Pseudonormal or restrictive filling patterns are related to progressive LV dilation and predict cardiac death after a first MI.

Aim: To evaluate the incremental value of sophisticated evaluation of leftventricular filling pressure for determining systolo-diastolic interactions. Methods: 51 patients underwent echography to evaluate systolic (ejection fraction (EF)), and diastolic functions (mitral Doppler for E/A, deceleration time(DT), E wave flow propagation velocity (Vp), early diastolic velocity of lateral mitral annulus (Ea)) and BNP. Results: Significant increases of BNP between the 3 tertiles for E/Vp(p