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Clostridioides difficile (CD) is a major nosocomial pathogen and the leading cause of antibiotic-associated diarrhoea. In light of the strong association between antimicrobial use and CD infections (CDI), it may be hypothesised that areas at higher prevalence of antimicrobial resistance, like the region of Campania in southern Italy, could also have a higher rate of CDI. In this multicentre, region-based, prospective study, we analysed such issues, exploiting CDI incidence data collected from local hospitals. In 2016, the Italian National Centre for Disease Control supported a project involving three Italian regions: Friuli Venezia Giulia, Lazio and Campania. In Campania, a network of 49 hospitals willing to participate in the project was created. The project consisted of two phases: a survey on practice patterns concerning CDI and an epidemiological surveillance study. We identified a stringent need to improve awareness about CDI among the regional health-care community, as a widespread lack of surveillance programmes for CDI control was observed (existing in only 40% of participating facilities). Moreover, almost half of the participating hospitals (n=16, 43%) had no standardised procedures or protocols to control and prevent CDI. In the second phase of the study, we collected data of CDI cases during a six-month surveillance programme. In all, 87 CDI cases were observed, for a total of 903,334 patient bed-days and 122,988 admissions. According to the above data, CDI incidence was 0.96 cases/10000 patient bed-days, much lower than expected based on prior studies conducted elsewhere. The results of our study suggest CDI remains a rather neglected clinical issue in Campania. Despite a high burden of antimicrobial resistance and antimicrobial use in our geographic setting, we observed a very low incidence of CDI. Such a low incidence could be explained by underdiagnosis, but could also be related to actual diet, the lower patient age or the specific genetic background. However, further studies are warranted to either confirm or rebut the above hypotheses.

The one-dimensional numerical model presented in the present paper divides the flow in two fully coupled layers, a water layer and a water-sediment transport layer. Initially, this model was used to depict dam-break flows, which do not require a specific treatment of boundary conditions. The aim of the present research is to extend the model to fluvial flows requiring an appropriate boundary condition treatment. This treatment commonly relies on characteristics. However, in the frame of a two-layer model with five equations, those characteristics are not obvious to determine. This paper shows, how to extend numerically the common eigenstructure analysis to address the problem. Examples are presented and the boundary conditions treatment is illustrated on the particular case of a hydraulic jump over a mobile bed. Results of the numerical model including the adequate boundary conditions are favourably compared to experimental results.

Impulsive waves impinging over steep slopes of dams or embankments may produce erosion with intense sediment transport and relevant morphological changes during fast geomorphic transients. In order to be employed as valuable tools for risk assessment and hazard mitigation, the performance of current morphodynamic models in reproducing the physical evolution of such processes has to be carefully assessed. However, despite the inherent interest of the topic, the availability of suitable experimental data is relatively scarce. For this reason, additional tests, carried out under controlled conditions, may furnish the basis for an improvement in the knowledge of the bed evolution. The obtained experimental results constitute also an important resource to evaluate the numerical models performance. To this aim, a set of laboratory experiments, in which the impact of a dam break wave on an erodible slope is reproduced, has been designed and conducted. In the paper some preliminary results are presented and discussed.

The paper analyzes the influence of resistance coefficient dependence on flow variables, viscosity and wall roughness onto the spatial development of roll-waves in the initial phase. To this aim, two models, based on time-asymptotic solutions of linearized St. Venant equations, subjected to either impulsive or oscillating perturbation, have been modified by including the dependence of the resistance coefficient on flow conditions. Independently on the perturbation type, the results show that the hypothesis of constant resistance coefficient may lead to a non-negligible underestimation of the instability spatial growth rate. Theoretical achievements are compared with results of a fully non-linear model for several combinations of Froude and Reynolds numbers and relative roughness values. The comparison shows that the spatial linear analysis with a suitable oscillating perturbation allows to accurately reproduce both spatial growth rate and celerity of the roll-waves. Such findings have to be properly accounted for in defining criteria for roll-waves occurrence in natural and manmade channels.

Summary This paper analyses conditions for roll-waves formation in homogeneous granular flows with the aim of predicting their occurrence in finite length channels. With reference to a wide class of constitutive equations of the flowing medium, the response of the linearized one-dimensional flow model to a pointwise instantaneous disturbance is studied and a closed form of the Green’s function, in both stable and unstable conditions, is provided. The exponential growth of the disturbance peak is used to predict the spatial evolution of roll-waves in dry flows of dense granular materials and a criterion for the minimum channel length necessary to appreciate roll-wave development is proposed. The comparison among theoretical and experimental data available in the literature appears promising.

This paper presents a novel algorithm with improved convergence and robustness for the pressure-driven modeling of water distribution networks (WDNs), to be implemented as hydraulic engine in the fourth release of the SWANP version 4.0 software. The innovative approach is based on increasing the order of convergence, which is quadratic for algorithms obtained from the Newton Raphson linearization of the equations for WDN resolution. As an example, the cubic order of convergence is obtained by evaluating system matrices at the generic iteration in a more refined way to account for the curvature of the hyperplane associated with the system in the direction of the Newton Raphson step. To show the benefits of the methodology, a third-order algorithm is constructed and compared with a traditional second-order. Both algorithms are based on the direct pressure-driven formulation expressing outflows as a function of service pressure and are equipped with the dampening of the Newton Raphson step. Applications on two case studies of different size, in which challenging pressure-driven conditions are created through demand amplification and segment isolation scenarios, prove that the methodology always reduces the total number of iterations required for convergence and the application of the step dampening. Overall, the results also show that the more stable convergence behavior is accompanied by an appreciable reduction in computation times. Further analyses proved that the third-order algorithm has similar convergence properties to algorithms based on the inverse pressure-driven formulation recently proposed in the scientific literature and can therefore be considered as a valid alternative to these algorithms.

Mud flows represent one of the major causes of natural hazards in mountain regions. Similarly to debris flows, they consist of a hyper-concentrated mixture of water and sediments flowing down a slope and may cause serious damages to people and structures. The present paper investigates the force produced by a dam-break wave of mud impacting against a rigid wall. A power-law shear-thinning model is used to describe the rheology of the hyper-concentrated mixture. A one-dimensional shallow water model is adopted and a second-order Finite Volume scheme is employed to numerically solve the governing equations. The results indicate that depending on the fluid rheological parameters and on the bottom slope, there exists a minimum value of the wall distance above which the peak force does not exceed the asymptotic value of the hydrostatic final condition. For two different values of the channel slope, the dimensionless value of this lower bound is individuated for several values of the power-law exponent and of a dimensionless Basal Drag coefficient. An estimation of the maximum peak force for wall distance smaller than the minimum value is also provided.

The flow between two parallel plates driven by a pulsatile pressure gradient was studied analytically with a second-order velocity expansion. The resulting velocity distribution was compared with a numerical solution of the momentum equation to validate the analytical solution, with excellent agreement between the two approaches. From the velocity distribution, the analytical computation of the discharge, wall shear stress, discharge, and dispersion enhancements were also computed. The influence on the solution of the dimensionless governing parameters and of the value of the rheological index was discussed.

The adoption of the Diffusive Wave (DW) instead of the Full Dynamic (FD) model in the analysis of mud flood routing within the shallow-water framework may provide a significant reduction of the computational effort, and the knowledge of the conditions in which this approximation may be employed is therefore important. In this paper, the applicability of the DW approximation of a depth-integrated Herschel–Bulkley model is investigated through linear analysis. Assuming as the initial condition a steady hypocritical decelerated flow, induced by downstream backwater, the propagation characteristics of a small perturbation predicted by the DW and FD models are compared. The results show that the spatial variation on the initial profile may preclude the application of DW model with a prescribed accuracy. Whenever the method is applicable, the rising time of the mud flood must satisfy additional constraints, whose dependence on the flow depth, along with the Froude number and the rheological parameters, is deeply analyzed and discussed.

Climate change is exposing more and more frequently flood prone areas to potential casualties and damages. The capability of the flow to carry relevant quantities of sediments interacts with the presence of obstacles in flood-inundated areas and contributes to the increase the related hazard, constituting a relevant concern in the framework of risk analysis. Unfortunately, existing literature on this topic is rather scarce, especially for the features of sediment transport and the forces acting on rigid obstacles. In the paper, a recent two-phase shallow-water morphodynamical model, particularly suited to the analysis of fast geomorphic transients, is applied to the numerical simulation of the propagation of a dam-break wave over an erodible floodplain in presence of a rigid obstacle. The geometry of the test-case is inspired to a recent fixed-bed study reported in the literature, for which extensive experimental and numerical data concerning the flow field and the dynamic loading against the obstacle are available. Results of the numerical simulations contribute to highlight the effect of the obstacle on the changes in the bottom topography, along with the subsequent change on the loading condition on it. * Corresponding author Engineering EPiC SeriesinEngineering Volume3,2018,Pages564571 HIC 2018.13thInternational Conference onHydroinformatics G.

Simplified wave models - such as kinematic, diffusion and quasi-steady - are widely employed as a convenient replacement of the full dynamic one in the analysis of unsteady open-channel flows, and especially for flood routing. While their use may guarantee a significant reduction of the computational effort, it is mandatory to define the conditions in which they may be confidently applied. The present paper investigates the applicability conditions of the kinematic, diffusion and quasisteady dynamic shallow wave models for mud flows of power-law fluids. The power-law model describes in an adequate and convenient way fluids that at low shear rates fluids do not posses yield stress, such as clay or kaolin suspensions, which are frequently encountered in Chinese rivers. In the framework of a linear analysis, the propagation characteristics of a periodic perturbation of an initial steady uniform flow predicted by the simplified models are compared with those of the full dynamic one. Based on this comparison, applicability criteria for the different wave approximations for mud flood of power-law fluids are derived. The presented results provide guidelines for selecting the appropriate approximation for a given flow problem, and therefore they may represent a useful tool for engineering predictions.

"The occurrence of roll-waves in mud-flows is commonly investi-gated starting from the formulation of the marginal stability threshold of a linearized one-dimensional viscoplastic (shear-thinning) flow model. Since for this non-newtonian rheological model such a threshold may oc-cur in hypocritical flow, the downstream boundary condition may have a non-negligible effect on the spatial growth\/decay of the perturbation. The paper presents the solution of the 1D linearized flow of a Herschel & Bulkley fluid in a channel of finite length, in the neighbourhood of a hypocritical base uniform flow. Both linearly stable and unstable condi-tions are considered. The analytical solution is found applying the Laplace transform method and obtaining the first-order analytical expressions of the upstream and downstream channel response functions in the time domain. The effects of both the yield stress and the rheological law exponent are discussed, recovering as particular cases both power-law and Bingham fluids. The theoretical achievements may be used to extend semi-empirical criteria commonly employed for predicting roll waves occurrence in clear-water even to mud-flows."

The formulation of nonsteroidal anti-inflammatory drugs with cyclodextrins (CDs) has demonstrated to be a suitable strategy to increase drug aqueous solubility, dissolution rate, and gastric tolerance.We investigated the effects of the CDs on the physicochemical and pharmacological properties of Etodolac (ET), a practically water-insoluble nonsteroidal anti-inflammatory drug, to individuate a drug formulation with optimized pharmacokinetics and pharmacodynamics.The interactions in solution of ET with beta-CD, hydroxypropyl-beta-CD (HP-beta-CD), and gamma-CD were studied by (13)C-NMR spectroscopy and phase solubility method. Solid binary systems, prepared by physical mixing and freeze-drying, were characterized by differential scanning calorimetry, X-ray analysis and Fourier transform infrared spectroscopy, and dissolution studies. An in vivo pharmacological investigation (analgesic activity and gastric tolerance studies) was performed on freeze-dried ET/CD formulations.(13)C-NMR and phase solubility studies demonstrated the ability of CDs to complex with ET and increase drug solubility. ET/CD interactions at the solid state occurred at the molecular level only for freezed-dried samples. All binary systems, mainly those containing HP-beta-CD and gamma -CD, showed a significantly improved dissolution profile of ET. In vivo pharmacological studies evidenced an improvement of analgesic activity and a reduction of gastrolesivity of ET/CD-tested formulations with respect to ET alone.The formulation of ET with CDs demonstrates relevant pharmaceutical potential in view of decreasing dose and side effects of ET. For industrial applications, HP-beta-CD appears to be the best partner for ET, as it is less expensive than gamma-CD and gives rise to higher drug solubilization than beta-CD.

The study of unsteady shallow-layer flows, as those occurring during floods, may be performed through either fully dynamic models or using simplified momentum equations (e.g. kinematic, diffusion and quasi-steady approximations). Among the latter, kinematic approximation may provide a significant reduction of the computational effort, which represents a key advantage in time-critical applications. The proper application of this simplified model is however generally subjected to some limitations, which the modeler has to know and accurately verify to avoid errors. The present paper aims to investigate the applicability range of the kinematic approximation to shallow flows, with special concern to unsteady mud-flows, such as the hyper-concentrated floods. In the present analysis the rheological model proposed by O'Brien et al. (1993), broadly appreciated and widespread in the technical community, is considered. This model relies on a quadratic relationship linking the shear rate to the total shear stress, accounting for turbulent, dispersive and cohesive yield stresses. To provide relatively simple applicability criteria, linear analysis is applied to compare the celerity of a small perturbation of an initial steady uniform flow as predicted by the simplified model with those of the full dynamic model. Based on this comparison, applicability criteria for the kinematic approximation for mud-flows are derived. In particular, the proposed criteria rely on the comparison between the flood rising-time and a threshold time-scale: whenever the former is larger than the latter, the estimation of the propagation celerity of the simplified model is guaranteed with a prescribed accuracy. These criteria are presented considering the effect of all model parameters, based on the particular case of a pyroclastic mud, typically encountered in volcanic areas of southern Italy. The achieved results are discussed, aiming to guide the choice of the appropriate simplified model for mud flood analysis