183 research outputs found

    Effects of floaters on the free surface profiles of river flows

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    The presence of floaters should be taken into account when dealing with hydraulic analyses, e.g. when boats are moored along the river banks or large wood is expected to be conveyed by the river flow during floods. Many approaches have been proposed so far in order to consider the effects of floaters upon the flow features. Usually, they rely on the numerical resolution of the governing equation for both the fluid and the solid phases. Hence, their computational cost can be inadequate at the early stage of hydraulic studies or when large scale analyses have to be performed. A simplified method to compute the value of the resistance coefficient able to reproduce the effects of floaters upon the flow levels is proposed herein. The method is intended to provide the hydraulic parameters to be used within standard hydraulic simulations for which the effects of floaters must be accounted for; this is obtained by means of a modified resistance coefficient

    Beach drainage system: a comprehensive review of a controversial soft-engineering method

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    The beach drainage can be included among the soft engineering methods aimed to counteract the shoreline retreat related to the sediment redistribution along the beach profile. The idea that the groundwater table plays a role in the mobilization of the sediment grains underlies the application of the beach drainage system (BDS) as a tool able to modify the natural dynamics of groundwater table at sandy beaches. Indeed, BDS consists of a series of alongshore buried drains aimed to lower the groundwater table. Due to the drainage, the thickening of the layer of dry sand makes the solid grains less prone to be mobilized by the action of the waves at the swash zone, where interaction phenomena between the percolating and the incoming water lens take place. This tool had a troubled history. Its first applications were encouraging. Since then, controversial performances of both experimental and prototype scale experiences have been observed around the world. This paper aims to present an up-to-date full review of the studies and experiments carried out so far, in order to provide the reader with a complete perspective on its strength and weakness as well as open challenges to be faced in the near future

    Mapping and classification of ports and marinas for the definition of long-term development strategy

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    Mapping and classification of ports may be of great help to define effective development strategies based on the concept of “intelligent, green and integrated port”, within the frame of sustainable development. To this end, classification tools and knowledge of the initial situation are crucial points needed, just as an example, to boost the maritime and short-sea connectivity by promoting the creation of regional touristic port network, capable of implementing a smart, green, and integrated transport system. This work deals with the mapping and classification of ports and marinas. A possible methodology to define a priority matrix intervention rank is proposed and applied to all the harbors in the Puglia region, as a case study. The collected open data aim to describe several aspects: the services, the urban planning whereby the port is thought, the facilities and structures, the connection with multi-modal local transport. The mapping activity has been performed within the frame of the AI-SMART project funded by the European Regional Development Fund that aims to implement and develop a common port network in the Adriatic-Ionian area. The case study served to highlight the feasibility and applicability of the proposed method to a real case

    Numerical Modelling of Landslide-Generated Tsunamis with OpenFOAMÂź: a New Approach

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    In this paper we present a new method for numerically modelling landslide-generated tsunamis in OpenFOAMÂź by using a new approach based on the Overset mesh technique. This technique, which is based on the use of two (or more) numerical domains, is new in the coastal engineering field and appears to be extremely powerful to model the interaction between a moving body and one or more fluids. Indeed, the accurate resolution around the moving body (i.e. body-fitted approach), guaranteed by this method, offers a great advantage to study the momentum exchange between the body and the water. Furthermore, in order to overcome a drawback of the Overset mesh implementation we modelled the solid boundaries, along which the landslide body moves, as a porous media with a very low permeability. The new approach has been preliminarily, and successfully, validated through the numerical reproduction of past experiments for landslide-generated tsunamis triggered by a solid and impermeable wedge at a sloping coast

    Tsunamis Generated by Submerged Landslides: Numerical Analysis of the Near-Field Wave Characteristics

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    ABSTRACT: The accurate modeling of the landslide?generated tsunami characteristics in the so-called near-field is crucial for many practical applications. In this paper, we present a new full-3-D numerical method for modeling tsunamis generated by rigid and impermeable landslides in OpenFOAM¼ based on the overset mesh technique. The approach has been successfully validated through the numerical reproduction of past experiments for landslide?generated tsunamis triggered by a rigid and impermeable wedge at a sloping coast. The method has been applied to perform a detailed numerical study of the near-field wave features induced by submerged landslides. A parametric analysis has been carried out to explore the importance of the landslide's initial acceleration, directly related to the landslide-triggering mechanisms, on the tsunami generation process and on the related wave properties. Near-field analysis of the numerical results confirms that the influence of the initial acceleration on the tsunami wave properties is significant, affecting wave height, wave period, and wave celerity. Furthermore, it is found that the tsunami generation mechanism experiences a saturation effect for increasing landslide's initial acceleration, confirming and extending previous studies. Moreover, the resulting extended database, composed of previous experimental data and new numerical ones, spanning a wider range of governing parameters, has been represented in the form of a “nondimensional wavemaker curve,” and a new relationship for predicting the wave properties in the near-field as a function of the Hammack number is proposed

    “It is all about the fear of being discriminated [against]
the person suffering from HIV will not be accepted”: a qualitative study exploring the reasons for loss to follow-up among HIV-positive youth in Kisumu, Kenya

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    BACKGROUND: Youth represent 40% of all new HIV infections in the world, 80% of which live in sub-Saharan Africa. Youth living with HIV (YLWH) are more likely to become lost to follow-up (LTFU) from care compared to all other age groups. This study explored the reasons for LTFU among YLWH in Kenya. METHODS: Data was collected from: (1) Focus group Discussions (n = 18) with community health workers who work with LTFU youth. (2) Semi-structured interviews (n = 27) with HIV + youth (15–21 years old) that had not received HIV care for at least four months. (3) Semi-structured interviews (n = 10) with educators selected from schools attended by LTFU interview participants. Transcripts were coded and analyzed employing grounded theory. RESULTS: HIV-related stigma was the overarching factor that led to LTFU among HIV + youth. Stigma operated on multiple levels to influence LTFU, including in the home/family, at school, and at the clinic. In all three settings, participants’ fear of stigma due to disclosure of their HIV status contributed to LTFU. Likewise, in the three settings, the dependent relationships between youth and the key adult figures in their lives were also adversely impacted by stigma and resultant lack of disclosure. Thus, at all three settings stigma influenced fear of disclosure, which in turn impacted negatively on dependent relationships with adults on whom they rely (i.e. parents, teachers and clinicians) leading to LTFU. CONCLUSIONS: Interventions focusing on reduction of stigma, increasing safe disclosure of HIV status, and improved dependent relationships may improve retention in care of YLWH

    Language production impairments in patients with a first episode of psychosis

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    A multi-element psychosocial intervention for early psychosis (GET UP PIANO TRIAL) conducted in a catchment area of 10 million inhabitants: study protocol for a pragmatic cluster randomized controlled trial

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    Multi-element interventions for first-episode psychosis (FEP) are promising, but have mostly been conducted in non-epidemiologically representative samples, thereby raising the risk of underestimating the complexities involved in treating FEP in 'real-world' services

    Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

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    Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat
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