395 research outputs found

    Feedback-controlled laser ablation for cancer treatment: comparison of On-Off and PID control strategies

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    : Laser ablation is a rising technique used to induce a localized temperature increment for tumor ablation. The outcomes of the therapy depend on the tissue thermal history. Monitoring devices help to assess the tissue thermal response, and their combination with a control strategy can be used to promptly address unexpected temperature changes and thus reduce unwanted thermal effects. In this application, numerical simulations can drive the selection of the laser control settings (i.e., laser power and gain parameters) and allow evaluating the thermal effects of the control strategies. In this study, the influence of different control strategies (On-Off and PID-based controls) is quantified considering the treatment time and the thermal effect on the tissue. Finite element model-based simulations were implemented to model the laser-tissue interaction, the heat-transfer, and the consequent thermal damage in liver tissue with tumor. The laser power was modulated based on the temperature feedback provided within the tumor safety margin. Results show that the chosen control strategy does not have a major influence on the extent of thermal damage but on the treatment duration; the percentage of necrosis within the tumor domain is 100% with both strategies, while the treatment duration is 630 s and 786 s for On-Off and PID, respectively. The choice of the control strategy is a trade-off between treatment duration and unwanted temperature overshoot during closed-loop laser ablation. Clinical Relevance-This work establishes that different temperature-based control of the laser ablation procedure does not have a major influence on the extent of thermal damage but on the duration of treatment

    Time Domain Source Parameter Estimation of Natural and Man-Induced Microearthquakes at the Geysers Geothermal Field

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    Water injection in geothermal areas is the preferential strategy to sustain the natural production of geothermal resources. In this context, monitoring microearthquakes is a fundamental tool to track changes in the reservoirs in terms of soil composition, response to injections, and resource exploitation with space and time. Therefore, refined source characterization is crucial to better estimate the size, source mechanism, and rupture process of microearthquakes, as they are possibly related to industrial activities, and to identify any potential variation in the background seismicity. Standard approaches for source parameter estimation are ordinarily based on the modelling of Fourier displacement spectra and its characteristic parameters: the low-frequency spectral level and corner frequency. Here, we apply an innovative time domain technique that uses the curves of P-wave amplitude vs. time along the seismogram. This methodology allows estimation of seismic moment, source radius, and stress release from the plateau level and the corner time of the average logarithm of P-wave displacement versus time with the assumption of a triangular moment rate function, uniform rupture speed, and a constant/frequency-independent Q-factor. In the current paper, this time domain methodology is implemented on a selected catalog of microearthquakes consisting of 83 events with a moment magnitude ranging between 1.0 and 1.5 that occurred during a 7-year period (2007–2014) of fluid extraction/injection around Prati-9 and Prati-29 wells at The Geysers geothermal field. The results show that the time domain technique provides accurate seismic moment (moment magnitude) and rupture duration/radius estimates of microearthquakes down to the explored limit (M 1) while accounting for the anelastic attenuation effect in the radiated high-frequency wavefield. The retrieved source radius vs. moment scaling is consistent with a self-similar, constant stress drop scaling model, which proves an appropriate attenuation correction and the validity of the assumed, triangular moment rate function for microearthquake ruptures. Two alternative mechanical models are proposed to explain the observed difference (about two orders of magnitude) in the retrieved average stress release estimates between the time and frequency domain methods. We argue that the two quantities may not refer to the same physical quantity representing the stress release of earthquake ruptures. Either the smaller stress release values from the time domain method may indicate a larger fracture area (by a factor of 20) radiating the observed P-waveforms than the one estimated from the corner frequencies, or the frequency domain estimate is a proxy for dynamic stress release while the time domain is more representative of the static release. The latter is associated with a much lower dynamic friction value than static friction value at the fault during the rupture process

    Sharing health data among general practitioners: The Nu.Sa. project

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    Today, e-health has entered the everyday work flow in the form of a variety of healthcare providers. General practitioners (GPs) are the largest category in the public sanitary service, with about 60,000 GPs throughout Italy. Here, we present the Nu.Sa. project, operating in Italy, which has established one of the first GP healthcare information systems based on heterogeneous data sources. This system connects all providers and provides full access to clinical and health-related data. This goal is achieved through a novel technological infrastructure for data sharing based on interoperability specifications recognised at the national level for messages transmitted from GP providers to the central domain. All data standards are publicly available and subjected to continuous improvement. Currently, the system manages more than 5,000 GPs with about 5,500,000 patients in total, with 4,700,000 pharmacological e-prescriptions and 1,700,000 e-prescriptions for laboratory exams per month. Hence, the Nu.Sa. healthcare system that has the capacity to gather standardised data from 16 different form of GP software, connecting patients, GPs, healthcare organisations, and healthcare professionals across a large and heterogeneous territory through the implementation of data standards with a strong focus on cybersecurity. Results show that the application of this scenario at a national level, with novel metrics on the architecture's scalability and the software's usability, affect the sanitary system and on GPs’ professional activities

    Prospective Improvements for Safer Fuel Tanks: Experimental Tests

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    In past studies, some of the authors presented how the integration of different systems, for the prevention of fires or explosions due to impact or bullet damage, may significantly improve the safety of fuel tanks. Leakage, after bullet penetration or debris impact, can be significantly reduced by introducing polymeric materials with self-healing capabilities for the container’s walls, while an internal aluminium filler can reduce the sloshing and the danger of fuel ignition. In the present paper, an experimental evaluation of the proposed solution is presented. A ballistic test campaign on a fluid container was performed to investigate the interaction between an ethylene–methacrylic acid (EMAA)-based ionomeric wall (i.e. Dupont®Surlyn 8940) and an internal aluminium filler (i.e. Explosafe®). Results show that the presence of the fluid increases the self-healing capabilities, which are however slightly affected by the internal aluminium filler; the contribution in terms of sloshing reduction remains relevant. Moreover, additional configurations based on multilayer panels are presented. The authors studied the healing process of EMAA in a sandwich configuration made of one skin of ionomer and one skin of carbon fibre, sepa- rated by an aramidic honeycomb. The main objective of the honeycomb is to prevent the remarkable reduction of the healing capabilities observed when ionomer is directly coupled to aramidic fabric or composite panels. The new multilayer configurations have been tested at different impact conditions

    Filaggrin mutations in relation to skin barrier and atopic dermatitis in early infancy

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    Background Loss-of-function mutations in the skin barrier gene filaggrin (FLG) increase the risk of atopic dermatitis (AD), but their role in skin barrier function, dry skin and eczema in infancy is unclear. Objectives To determine the role of FLG mutations in impaired skin barrier function, dry skin, eczema and AD at 3 months of age and throughout infancy. Methods FLG mutations were analysed in 1836 infants in the Scandinavian population-based PreventADALL study. Transepidermal water loss (TEWL), dry skin, eczema and AD were assessed at 3, 6 and 12 months of age. Results FLG mutations were observed in 166 (9%) infants. At 3 months, carrying FLG mutations was not associated with impaired skin barrier function (TEWL > 11 center dot 3 g m(-2) h(-1)) or dry skin, but was associated with eczema [odds ratio (OR) 2 center dot 89, 95% confidence interval (CI) 1 center dot 95-4 center dot 28; P < 0 center dot 001]. At 6 months, mutation carriers had significantly higher TEWL than nonmutation carriers [mean 9 center dot 68 (95% CI 8 center dot 69-10 center dot 68) vs. 8 center dot 24 (95% CI 7 center dot 97-8 center dot 15), P < 0 center dot 01], and at 3 and 6 months mutation carriers had an increased risk of dry skin on the trunk (OR 1 center dot 87, 95% CI 1 center dot 25-2 center dot 80; P = 0 center dot 002 and OR 2 center dot 44, 95% CI 1 center dot 51-3 center dot 95; P < 0 center dot 001) or extensor limb surfaces (OR 1 center dot 52, 95% CI 1 center dot 04-2 center dot 22; P = 0 center dot 028 and OR 1 center dot 74, 95% CI 1 center dot 17-2 center dot 57; P = 0 center dot 005). FLG mutations were associated with eczema and AD in infancy. Conclusions FLG mutations were not associated with impaired skin barrier function or dry skin in general at 3 months of age, but increased the risk for eczema, and for dry skin on the trunk and extensor limb surfaces at 3 and 6 months.Peer reviewe
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