40 research outputs found
Lagrangian diffusive reactor for detailed thermochemical computations of plasma flows
No full textThe simulation of a thermochemical nonequilibrium for atomic and molecular energy level populations in plasma flows requires a comprehensive modeling of all the elementary collisional and radiative processes involved. Coupling detailed chemical mechanisms to flow solvers is computationally expensive and often limits their application to 1D simulations. We develop an efficient Lagrangian diffusive reactor moving along the streamlines of a steady baseline flow simulation to compute detailed thermochemical effects. In addition to its efficiency, the method allows us to model both continuum and rarefied flows, while including mass and energy diffusion. The Lagrangian solver is assessed for several testcases including strong normal shockwaves, as well as 2D and axisymmetric blunt-body hypersonic rarefied flows. In all the testcases performed, the Lagrangian reactor improves drastically the baseline simulations. The computational cost of a Lagrangian recomputation is typically orders of magnitude smaller with respect to a full solution of the problem. The solver has the additional benefit of being immune from statistical noise, which strongly affects the accuracy of calculations obtained by means of the Direct Simulation Monte Carlo method, especially considering minor species in the mixture. The results demonstrate that the method enables applying detailed mechanisms to multidimensional solvers to study thermochemical nonequilibrium flows
A self-consistent method for the simulation of meteor trails with an application to radio observations
No full textContext. Radio-based techniques allow for a meteor detection of 24 h. Electromagnetic waves are scattered by the electrons produced by the ablated species colliding with the incoming air. As the electrons dissipate in the trail, the received signal decays. The interpretation of these measurements entails complex physical modelling of the flow. Aims. In this work, we present a procedure to compute extensive meteor trails in the rarefied segment of the trajectory. This procedure is a general and standalone methodology, which provides meteor physical parameters at given trajectory conditions, without the need to rely on phenomenological lumped models. Methods. We started from fully kinetic simulations of the evaporated gas that describe the nonequilibrium in the flow and the ionisation collisions experienced by metals in their encounter with air molecules. These simulations were employed as initial conditions for performing detailed chemical and multicomponent diffusion calculations of the extended trail, in order to study the processes which lead to the extinction of the plasma. In particular, we focused on the evolution of the trail generated by a 1 mm meteoroid flying at 32 km s-1, above 80 km. We retrieved the ambipolar diffusion coefficient and the electron line density and compared the outcome of our computations with classical results and observational fittings. Finally, the electron field was employed to estimate the resulting reflected signal, using classical radio-echo theory for underdense meteors. Results. A global and constant diffusion coefficient is sufficient to reproduce numerical profiles. A good agreement is found when we compare the extracted diffusion coefficients with theory and observations
Mild-to-moderate foeto-maternal haemorrhage in the third trimester and at term of pregnancy: Quantitative determination and clinical-diagnostic evaluation
No full textBackground: Foeto-maternal haemorrhage (FMH), a gestational event that occurs before or during delivery, consists of a loss of foetal blood into the maternal circulation. FMH occurs more frequently during the third trimester or labour both in normal and complicated pregnancies. In the case of alloimmunisation, the maternal immunological response and the severity of the resulting foetal or neonatal disease depend on the amount of foetal blood that passes into the maternal circulation. The aim of this study was to determine FMH in the third trimester and at term of pregnancy and to evaluate the role of clinical and ultrasound markers in the prediction of FMH. Materials and methods: FMH was quantified by cytofluorimetric testing at 28 to 35 weeks of gestation in 223 women and at term in 465 women, all with risk factors. Foetal evaluation included foetal movement profile, middle cerebral artery peak velocity of systolic blood flow (MCA-PSV) and cardiotocographic monitoring. Results: All women tested negative for FMH in the third trimester. Four patients (0.9%) tested positive at term, with estimated volumes of bleeding of 2.2, 8.1, 12.3 and 39.8 mL. Three FMH cases (75%) had a non-reassuring cardiotocography compared to 8.9% (42/461) of women without FMH (p=0.003) and two FMH cases reported a reduction in foetal movements reduction compared to four of those without FMH (p=0.001). Mean MCA-PSV was normal in both the groups with and without FMH (p=0.22). Discussion: FMH is rare in pregnancy and at term. Cytofluorimetric testing is a specific method to detect mild-to-moderate FMH even when the MCA-PSV is not informative. Mild-to-moderate FMH is significantly associated with reduced foetal movements and non-reassuring cardiotocographic monitoring
The nonpsychoactive component of marijuana cannabidiol modulates chemotaxis and IL-10 and IL-12 production of murine macrophages both in vivo and in vitro.
No full textGonadal and uterine function in female survivors treated by chemotherapy, radiotherapy, and/or bone marrow transplantation for childhood malignant and non-malignant diseases
No full textObjective To evaluate gonadal function and uterine volume in a cohort of female survivors treated by chemotherapy, radiotherapy, and/or stem cell transplantation (SCT) for childhood malignant and non-malignant diseases. Design An observational study. Setting S. Matteo Hospital, Pavia, Italy. Population A cohort of 135 female survivors. Methods A clinical, hormonal, and ultrasonographic evaluation. Thirty-three patients (24%) had non-malignant haematologic diseases (thalassaemia or sickle cell anaemia), 68 (50%) had leukaemia, 23 (17%) had lymphomas, and 11 (8%) had solid tumours. In total, 106 patients had received SCT, preceded by a conditioning regimen. Main outcome measures Anti-Müllerian hormone (AMH) and Inhibin-B, and uterine volume. Results The median concentrations of AMH and Inhibin-B in the entire cohort were 0.12 ng/ml (interquartile range, IQR, 0.1-0.5 ng/ml) and 3.5 pg/ml (IQR 0.1-13.2 pg/ml), respectively. In a stepwise ordered logistic regression analysis, conventional chemotherapy for the treatment of malignancies, as opposed to total body irradiation (TBI), was the only oncologically significant predictor of increased AMH levels (OR 4.8, 95% CI 1.9-12, P < 0.001). Conditioning treatment before or after menarche did not influence AMH concentrations (P = 0.24). The best predictor of reduced uterine volume was TBI during the preparation for the allograft (OR 3.5, 95% CI 1.4-8.4, P = 0.006). Increasing age at treatment (OR 0.86, 95% CI 0.77-0.95, P = 0.04), chemotherapy, as opposed to other treatments (OR 0.09, 95% CI 0.03-0.28, P < 0.001), and solid tumours as opposed to either leukaemia/lymphomas or non-malignant diseases (OR 0.2, 95% CI 0.07-0.56, P = 0.002) were associated with larger uterine volumes. Conclusions Conditioning therapies for SCT, including TBI, had the worst effects on uterine volume and gonadal reserve. Increasing age at treatment and conventional chemotherapy were associated with less detrimental effects on uterine volume. © 2014 Royal College of Obstetricians and Gynaecologists
The non-psychoactive component of marijuana cannabidiol modulates chemotaxis and IL-10 and IL-12 production of murine macrophages both in vivo and in vitro
No full textCannabidiol is the main nonpsychoactive component of marijuana. We examined the ability of in vivo and in vitro cannabidiol to interfere with the production of interleukin (IL)-12 and IL-10 by murine macrophages and to modulate macrophage chemotaxis. Cannabidiol added in vitro to peritoneal macrophages significantly increased IL-12 and decreased IL-10 production. The CB1 and CB2 receptor antagonists prevented this modulation. Macrophages from animals treated with cannabidiol at the dose of 30 mg kg(-1) either orally or i.p. produced higher levels of IL-12 and lower levels of IL-10 in comparison to controls, and the CB receptor antagonists did not prevent these effects. Cannabidiol dose-dependently decreased fMLP-induced chemotaxis of macrophages, and the CB2 receptor antagonist prevented this decrease
Analysis of Meteoroid Ablation Based on Plasma Wind-tunnel Experiments, Surface Characterization, and Numerical Simulations
No full textMeteoroids largely disintegrate during their entry into the atmosphere, contributing significantly to the input of cosmic material to Earth. Yet, their atmospheric entry is not well understood. Experimental studies on meteoroid material degradation in high-enthalpy facilities are scarce and when the material is recovered after testing, it rarely provides sufficient quantitative data for the validation of simulation tools. In this work, we investigate the thermo-chemical degradation mechanism of a meteorite in a high-enthalpy ground facility able to reproduce atmospheric entry conditions. A testing methodology involving measurement techniques previously used for the characterization of thermal protection systems for spacecraft is adapted for the investigation of ablation of alkali basalt (employed here as meteorite analog) and ordinary chondrite samples. Both materials are exposed to a cold-wall stagnation point heat flux of 1.2 MW m-2. Numerous local pockets that formed on the surface of the samples by the emergence of gas bubbles reveal the frothing phenomenon characteristic of material degradation. Time-resolved optical emission spectroscopy data of ablated species allow us to identify the main radiating atoms and ions of potassium, calcium, magnesium, and iron. Surface temperature measurements provide maximum values of 2280 K for the basalt and 2360 K for the chondrite samples. We also develop a material response model by solving the heat conduction equation and accounting for evaporation and oxidation reaction processes in a 1D Cartesian domain. The simulation results are in good agreement with the data collected during the experiments, highlighting the importance of iron oxidation to the material degradation
Confusione sessuale delle tortrici del castagno mediante puffer: una storia di successi e sconfitte
No full textAnalysis of Meteoroid Ablation Based on Plasma Wind-tunnel Experiments, Surface Characterization, and Numerical Simulations
No full textAbstract Meteoroids largely disintegrate during their entry into the atmosphere, contributing significantly to the input of cosmic material to Earth. Yet, their atmospheric entry is not well understood. Experimental studies on meteoroid material degradation in high-enthalpy facilities are scarce and when the material is recovered after testing, it rarely provides sufficient quantitative data for the validation of simulation tools. In this work, we investigate the thermo-chemical degradation mechanism of a meteorite in a high-enthalpy ground facility able to reproduce atmospheric entry conditions. A testing methodology involving measurement techniques previously used for the characterization of thermal protection systems for spacecraft is adapted for the investigation of ablation of alkali basalt (employed here as meteorite analog) and ordinary chondrite samples. Both materials are exposed to a cold-wall stagnation point heat flux of 1.2 MW m−2. Numerous local pockets that formed on the surface of the samples by the emergence of gas bubbles reveal the frothing phenomenon characteristic of material degradation. Time-resolved optical emission spectroscopy data of ablated species allow us to identify the main radiating atoms and ions of potassium, calcium, magnesium, and iron. Surface temperature measurements provide maximum values of 2280 K for the basalt and 2360 K for the chondrite samples. We also develop a material response model by solving the heat conduction equation and accounting for evaporation and oxidation reaction processes in a 1D Cartesian domain. The simulation results are in good agreement with the data collected during the experiments, highlighting the importance of iron oxidation to the material degradation.FWOFRIABELSPOFW
