Customized finite element modelling of the human cornea

Aim To construct patient-specific solid models of human cornea from ocular topographer data, to increase the accuracy of the biomechanical and optical estimate of the changes in refractive power and stress caused by photorefractive keratectomy (PRK). Method Corneal elevation maps of five human eyes were taken with a rotating Scheimpflug camera combined with a Placido disk before and after refractive surgery. Patient-specific solid models were created and discretized in finite elements to estimate the corneal strain and stress fields in preoperative and postoperative configurations and derive the refractive parameters of the cornea. Results Patient-specific geometrical models of the cornea allow for the creation of personalized refractive maps at different levels of IOP. Thinned postoperative corneas show a higher stress gradient across the thickness and higher sensitivity of all geometrical and refractive parameters to the fluctuation of the IOP. Conclusion Patient-specific numerical models of the cornea can provide accurate quantitative information on the refractive properties of the cornea under different levels of IOP and describe the change of the stress state of the cornea due to refractive surgery (PRK). Patient-specific models can be used as indicators of feasibility before performing the surgery. Copyright: © 2015 Simonini, Pandolfi

Effectiveness of distributed temperature measurements for early detection of piping in river embankments

Abstract. Internal erosion is the cause of a significant percentage of failure and incidents involving both dams and river embankments in many countries. In the past 20 years the use of fibre-optic Distributed Temperature Sensing (DTS) in dams has proved to be an effective tool for the detection of leakages and internal erosion. This work investigates the effectiveness of DTS for dike monitoring, focusing on the early detection of backward erosion piping, a mechanism that affects the foundation layer of structures resting on permeable, sandy soils. The paper presents data from a piping test performed on a large-scale experimental dike equipped with a DTS system together with a large number of accompanying sensors. The effect of seepage and piping on the temperature field is analysed, eventually identifying the processes that cause the onset of thermal anomalies around piping channels and thus enable their early detection. Making use of dimensional analysis, the factors that influence this thermal response of a dike foundation are identified. Finally some tools are provided that can be helpful for the design of monitoring systems and for the interpretation of temperature data

Exploring the Antimicrobial Potential of Hallachrome, a Defensive Anthraquinone from the Marine Worm Halla parthenopeia (Polychaeta)

Antimicrobial resistance is a critical global health issue, with rising resistance among bacteria and fungi. Marine organisms have emerged as promising, but underexplored, sources of new antimicrobial agents. Among them, marine polychaetes, such as Halla parthenopeia, which possess chemical defenses, could attract significant research interest. This study explores the antimicrobial properties of hallachrome, a unique anthraquinone found in the purple mucus of H. parthenopeia, against Gram-negative bacteria (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 9027), Gram-positive bacteria (Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 12228), and the most common human fungal pathogen Candida albicans ATCC 10231. Antibacterial susceptibility testing revealed that Gram-negative bacteria were not inhibited by hallachrome at concentrations ≤2 mM. However, Gram-positive bacteria showed significant growth inhibition at 0.12–0.25 mM, while C. albicans was inhibited at 0.06 mM. Time-kill studies demonstrated dose-dependent growth inhibition of susceptible strains by hallachrome, which exerted its effect by altering the membrane permeability of C. albicans, E. faecalis, and S. epidermidis after 6 h and S. aureus after 24 h. Additionally, hallachrome significantly reduced biofilm formation and mature biofilm in S. aureus, E. faecalis, and C. albicans. Additionally, it inhibited hyphal growth in C. albicans. These findings highlight hallachrome’s potential as a novel antimicrobial agent, deserving further exploration for clinical experimentation

Evaluation of dynamic explicit mpm formulations for unsaturated soils

Many applications in geohazards prevention involve large deformations of unsaturated soils, e.g. rainfall induced landslides, embankment collapses due to wetting etc. These phenomena can be investigated with multiphase implementations of the Material Point Method (MPM) able to account for the behaviour of unsaturated soils. This paper compares two formulations: (i) afully coupled three-phase formulation(3P)in which the governing equations are derived from the momentum balance and the mass balance equations of solid, liquid and gas phase assuming non-zero gas pressure,the primary unknowns are the absolute accelerationsof the phases (aS–aL–aG formulation); (ii)a simplified approachthatneglectsthe momentum balance equation of the gas(2P_s).Potentialities and limitations of these approaches are highlighted consideringa 1D infiltration problem.Despite the introduced simplifications, the simplified formulation gives reasonably good results in many engineering cases

Kinematics of gaits in Bardigiano horses

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Non-Isothermal sloshing for space applications: from a ground-based experimental characterisation to microgravity conditions

Liquid cryogenic propellants are at the forefront of space propulsion due to their optimal trade-off between performance and weight (Sutton et al. 2017). As a result, investigations on the sloshing dynamics of such fuels have been carried out since the early 1960s. Sloshing, defined as the movement of the free liquid surface within a reservoir (Abramson, 1966), induces two types of undesirable effects: (a) displacement of fuel tank’s centre of mass, which disturbs the stability and manoeuvrability of the spacecraft; (b) thermal mixing between the pressurised ullage and subcooled liquid, which can generate large fluctuations in the tank pressure, leading to structural instabilities and thrust oscillations in the propulsive system. [...]This work is supported by the European Space Agency (ESA) in the framework of the project number 4000129315/19/NL/MG. The authors gratefully acknowledge the financial support of the “Fonds de la Recherche Scientifique (F.R.S.-FNRS)” for the FRIA grant supporting the PhD of Mr Marques.info:eu-repo/semantics/publishedVersio

Giant hydatid lung cyst in non-endemic area

Abstract Echinococcosis is a parasitic zoonosis in which humans are involved as an intermediate host. It is a very common pathology in the areas of Eastern Europe and Asia, where the main activity is represented by pastoralism and animal breeding. In humans, the most frequently affected sites are the liver (60–70%) and lungs (20–30%), manifesting themselves with symptoms such as abdominal pain, coughing, dyspnea, hemoptysis, up to cases of anaphylactic shock. In Italy it is not a common disease with an incidence of 2:100.000 inhabitants, and it's extremely rare in pediatric population. In this work we presented a case of a 11-years male patient came for a persistent cough, to whom was found a giant cystic mass in the thorax. Serological tests confirmed the diagnosis of echinococcosis. Patient underwent to thoracotomy to remove the cyst and he begun the antiparasitic therapy. Post-operative outcome was good and the patient is, until now, free of problems. Echinococcosis is a challenging problem for a pediatric surgeon, especially in non-endemic area, not only because it is not a common disease in pediatric population, but also for the surgical management that can presents some difficulties and complications in the post-operative course