Le conoscenze in Física all'inizio dei corsi universitari in Italia

The article reports the results of an investigation on Italian university students concerning physics knowledge related to common sense schemes at the beginning of the university courses. The results of the diagnosis were communicated both to the students and to the teachers of the courses. The communication enabled the teachers, in the didactical practice, to pinpoint and discuss with the students the discrepancies between the scientific newtonian scheme and common sense scheme. A posttest, given at the end of the course, gives the indication that this practice is effective in inducing a change in the students ideas, notwithstanding the fact that no complete understanding of the scientific viewpoint is teached by the majority of students

Experimental assessment on exploiting low carbon ethanol fuel in a light-duty dual-fuel compression ignition engine

Compression ignition (CI) engines are widely used in modern society, but they are also recognized as a significative source of harmful and human hazard emissions such as particulate matter (PM) and nitrogen oxides (NOx). Moreover, the combustion of fossil fuels is related to the growing amount of greenhouse gas (GHG) emissions, such as carbon dioxide (CO2). Stringent emission regulatory programs, the transition to cleaner and more advanced powertrains and the use of lower carbon fuels are driving forces for the improvement of diesel engines in terms of overall efficiency and engine-out emissions. Ethanol, a light alcohol and lower carbon fuel, is a promising alternative fuel applicable in the dual-fuel (DF) combustion mode to mitigate CO2 and also engine-out PM emissions. In this context, this work aims to assess the maximum fuel substitution ratio (FSR) and the impact on CO2 and PM emissions of different nozzle holes number injectors, 7 and 9, in the DF operating mode. The analysis was conducted within engine working constraints and considered the influence on maximum FSR of calibration parameters, such as combustion phasing, rail pressure, injection pattern and exhaust gas recirculation (EGR). The experimental tests were carried out on a single-cylinder light-duty CI engine with ethanol introduced via port fuel injection (PFI) and direct injection of diesel in two operating points, 1500 and 2000 rpm and at 5 and 8 bar of brake mean effective pressure (BMEP), respectively. Noise and the coefficient of variation in indicated mean effective pressure (COVIMEP) limits have been chosen as practical constraints. In particular, the experimental analysis assesses for each parameter or their combination the highest ethanol fraction that can be injected. To discriminate the effect on ethanol fraction and the combustion process of each parameter, a one-at-a-time-factor approach was used. The results show that, in both operating points, the EGR reduces the maximum ethanol fraction injectable; nevertheless, the ethanol addition leads to outstanding improvement in terms of engine-out PM. The adoption of a 9 hole diesel injector, for lower load, allows reaching a higher fraction of ethanol in all test conditions with an improvement in combustion noise, on average 3 dBA, while near-zero PM emissions and a reduction can be noticed, on the average of 1 g/kWh, and CO2 compared with the fewer nozzle holes case. Increasing the load insensitivity to different holes number was observed

Occurrence of gas phase ammonia in the area of Beijing (China)

The atmospheric concentrations of gaseous ammonia have been measured during two field campaigns in the winter and in the summer of 2007 at Beijing (China). These measurements were carried out by means of diffusion annular denuders coated with phosphorous acid. The results were discussed from the standpoint of temporal and diurnal variations and meteorological effects. The daily average NH<sub>3</sub> concentrations were in the range of 0.20–44.38 μg/m<sup>3</sup> and showed regular temporal variations with higher concentrations during summer and with lower during winter. The temporal trends seemed to be largely affected by air temperature because of agricultural sources. No diurnal variability was observed for gaseous NH<sub>3</sub> levels in both winter and summer seasons. The highest ammonia value of 105.67 μg/m<sup>3</sup> was measured in the early morning during the summer period when stable atmospheric conditions occurred. The diurnal winter and summer trends of ammonia showed a weak dependence on the air temperature and they were affected nearly by wind direction suggesting regional and local source influences. Ammonia was also correlated with the atmospheric mixing in the boundary layer, and, with NO<sub>x</sub>, CO and PM<sub>2.5</sub> air concentrations supporting the hypothesis that the traffic may be also an important source of ammonia in Beijing

Coronary Artery Disease: A Study on the Joint Role of Birth Weight, Adenosine Deaminase, and Gender

An inverse relationship between birth weight and coronary artery diseases is well documented but it remains unclear which exposure in early life might underlie such association. Recently it has been reported an association between adenosine deaminase genetic polymorphism and coronary artery diseases. Gender differences in the degree of this association have been also observed. These observations prompted us to study the possible joint effects of BW, ADA, and gender on the susceptibility to coronary artery diseases. 222 subjects admitted to hospital for nonfatal coronary artery diseases, and 762 healthy consecutive newborns were studied. ADA genotypes were determined by DNA analysis. A highly significant complex relationship has emerged among ADA, birth weight, and gender concerning their role on susceptibility to coronary artery diseases in adult life. Odds ratio analysis suggests that low birth weight is more important in females than in males. ADA∗2 allele appears protective in males, while in females such effect is obscured by birth weight

Predictors of lymphocyte count recovery after dimethyl fumarate-induced lymphopenia in people with multiple sclerosis

Background: Dimethyl fumarate (DMF) is an oral drug approved for Relapsing Multiple Sclerosis (RMS) patients. Grade III lymphopenia is reported in 5–10% DMF-treated patients. Data on lymphocyte count (ALC) recovery after DMF withdrawal following prolonged lymphopenia are still scarce. Objectives: To characterize ALC recovery and to identify predictors of slower recovery after DMF interruption. Methods: Multicenter data from RMS patients who started DMF and developed lymphopenia during treatment were collected. In patients with grade II–III lymphopenia, ALCs were evaluated from DMF withdrawal until reaching lymphocyte counts > 800/mm3. Results: Among 1034 patients who started DMF, we found 198 (19.1%) patients with lymphopenia and 65 patients (6.3%) who discontinued DMF due to persistent grade II–III lymphopenia. Complete data were available for 51 patients. All patients recovered to ALC > 800 cells/mm3 with a median time of 3.4 months. Lower ALCs at DMF suspension (HR 0.98; p = 0.005), longer disease duration (HR 1.29; p = 0.014) and prior exposure to MS treatments (HR 0.03; p = 0.025) were found predictive of delayed ALC recovery. Conclusion: ALC recovery after DMF withdrawal is usually rapid, nevertheless it may require longer time in patients with lower ALC count at DMF interruption, longer disease duration and previous exposure to MS treatments, potentially leading to delayed initiation of a new therapy

Seasonal variation of antiretroviral drug exposure during the year: The experience of 10 years of therapeutic drug monitoring

Although studies show an annual trend for immunosuppressive drugs, particularly during different seasons, no data are available for antiretroviral drugs exposures in different periods of the year. For this reason, the aim of this study was to investigate an association between seasonality and antiretroviral drugs plasma concentrations. Antiretroviral drugs exposures were measured with liquid chromatography validated methods. A total of 4148 human samples were analysed. Lopinavir, etravirine and maraviroc levels showed seasonal fluctuation. In detail, maraviroc and etravirine concentrations decreased further in summer than in winter. In contrast, lopinavir concentrations had an opposite trend, increasing more in summer than in winter. The etravirine efficacy cut-off value of 300 ng/mL seems to be affected by seasonality: 77.1% and 22.9% of samples achieved this therapeutic target, respectively, in winter and summer, whereas 30% in winter and 70% in summer did not reach this value. Finally, age over 50 years and summer remained in the final multivariate regression model as predictors of the etravirine efficacy cut-off. This study highlights the seasonal variation in antiretroviral drugs plasma concentrations during the year, leading to a better understanding of inter-individual variability in drug exposures. Studies are required in order to confirm these data, clarifying which aspects may be involved