The comment

Libertà è possibilità di scegliere, ma non c'è vera scelta senza conoscenza. E buona parte della conoscenza (quella che non acquisiamo per esperienza diretta) ci viene dai libri. Per questo le biblioteche sono strumenti essenziali per l'esercizio della libertà, e per questo vanno promosse e tutelate dalle istituzioni.Freedom is the freedom to choose, and every choice implies knowledge. As most of the knowledge (the one that does not originate form direct experience) comes from books, libraries are essential for exercising our freedom: that's why they have to be preserved and supported by state institutions

Quantitative visualization of oil-water mixture behind sudden expansion by high speed camera

The present work describes the application of an image processing technique to study the two phase flow of high viscous oil and water through a sudden expansion. Six different operating conditions were considered, depending on input volume fraction of phases, and all of them are resulting in a flow pattern of the type oil dispersion in continuous water flow. The objective is to use an optical diagnostic method, with a high speed camera, to give detailed information about the flow field and spatial distribution, such as instantaneous velocity and in situ phase fraction. Artificial tracer particles were not used due to the fact that oil drops can be easily distinguished from the continuous water phase and thus they can act as natural tracers. The pipe has a total length of 11 meters and the abrupt sudden expansion is placed at a distance equal to 6 meters from the inlet section, to ensure that the flow is fully developed when it reaches the singularity. Upstream and downstream pipes have 30 mm and 50 mm i.d., respectively. Velocity profiles, holdup and drop size distribution after the sudden expansion were analyzed and compared with literature models and results

Measurement of the oil holdup for a two-phase oil-water flow through a sudden contraction in a horizontal pipe

Oil-water two-phase flow experiments were conducted in a horizontal duct made of Plexiglas to determine the holdup of oil by means of the quick closing valves technique, using mineral oil (viscosity: 0.838 Pa s at 20 °C; density: 890 kg m-3) and tap water. The duct presents a sudden contraction, with contraction ratio of 0.64. About 200 tests were performed by varying the flow rates of the phases. Flow patterns were investigated for both the up- and downstream pipe. Due to the relatively high value of the contraction ratio, it was not observed any relevant variation of the flow patterns across the sudden contraction. Data were then compared with predictions of a specific correlation for oil-water flow and some correlations for gas-water flow. A drift-flux model was also applied to determine the distribution parameter. The results agree quite well with flow pattern visualization

The Female Athlete's Heart: Facts and Fallacies.

Purpose of the review For many years, competitive sport has been dominated by men. Recent times have witnessed a significant increase in women participating in elite sports. As most studies investigated male athletes, with few reports on female counterparts, it is crucial to have a better understanding on physiological cardiac adaptation to exercise in female athletes, to distinguish normal phenotypes from potentially fatal cardiac diseases. This review reports on cardiac adaptation to exercise in females. Recent findings Recent studies show that electrical, structural, and functional cardiac changes due to physiological adaptation to exercise differ in male and female athletes. Women tend to exhibit eccentric hypertrophy, and while concentric hypertrophy or concentric remodeling may be a normal finding in male athletes, it should be evaluated carefully in female athletes as it may be a sign of pathology. Although few studies on veteran female athletes are available, women seem to be affected by atrial fibrillation, coronary atherosclerosis, and myocardial fibrosis less than male counterparts. Summary Males and females exhibit many biological, anatomical, and hormonal differences, and cardiac adaptation to exercise is no exception. The increasing participation of women in sports should stimulate the scientific community to develop large, longitudinal studies aimed at a better understanding of cardiac adaptation to exercise in female athletes

Investigações sobre corrupção em Milão, 1992/1998

In February 1992, what had begun as a simple case of extortion ended up by revealing that corruption in Italy had been widespread and systematic. More than five thousand people were investigated in the course of the enquiries, including Premiers, Members of Parliament, Ministers, and public and private entrepreneurs among others. The successful outcome of these investigations was achievable due to the conjugation of a series of elements: strong public opinion and media support, the independency of the Magistrates, Public Prosecutors and Judicial Police vis-à-vis the political sphere, and the efficiency of the strategy followed by the judiciary. Hampering even better results was the ineffectiveness of international judicial assistance, given that corrupt exchanges do often involve transnational cleaning operations.Em Fevereiro de 1992, uma investigação que começara com um simples caso de extorsão, acabaria por revelar a natureza generalizada e sistémica da corrupção em Itália. Mais de cinco mil indivíduos foram inquiridos no decorrer das investigações, incluindo, entre outros, Primeiro Ministros, Deputados, Ministros, altos cargos públicos e homens de negócios. O sucesso destas investigações só foi possível devido à conjugação de uma série de factores: o forte apoio por parte dos média e da opinião pública em geral; a independência, face à esfera politica, dos juízes, magistrados do ministério público e agentes da polícia judiciária; e a eficiência da estratégia de investigação prosseguida pela magistratura. Noentanto, um dos factores que mais terá condicionado a obtenção de melhores resultados foi a ineficácia da cooperação judicial internacional, dado que a maioria das transacções de natureza corrupta geralmente comportam operações transnacionais de branqueamento

SEMI-EMPIRICAL ANALYSIS OF THE CRITICAL TRANSITION FROM ANNULAR TO WAVY-STRATIFIED OIL-WATER ADIABATIC FLOW WITHIN HORIZONTAL AND SLIGHTLY INCLINED PIPES

The main subject of this paper concerns the critical transition from annular to wavy-stratified oil-water adiabatic flow within horizontal and slightly inclined pipes. The transition is referred to as critical because it occurs suddenly, giving rise to a sharp and strong increase in the pressure drop due to the contact of the high-viscosity oil with the pipe wall. This could be a dangerous accident, e.g. in pipelines operation, because the peak-wise increase in the pressure drop might give rise to a “chugging” phenomenon in the flow. Experimental runs were performed on eight test sections of both Plexiglas® and Pyrex® pipes with internal diameters ranging from 21.5 mm to 50 mm, using tap water and viscous oil (ρo=890 kg/m^3, μo=0.9 Pa s at 20°C). Inclination angles from 0 to 6 deg upward were tested. Water and oil superficial velocities were varied in their proper range and the pressure drop was measured for several combinations of these quantities. Flow pattern visualizations were also taken by a CCD photo-video camera in order to draw flow pattern maps. Based on these findings, the transition boundary between annular and wavy-stratified flow was analytically determined and compared with the data reported in the existing flow pattern maps

Influence of sudden contractions on in situ volume fractions for oil–water flows in horizontal pipes

Oil–water two-phase flow experiments were conducted in horizontal ducts made of Plexiglas® to determine the in situ oil fraction (holdup) by means of the closing valves technique, using mineral oil (viscosity: 0.838 Pa s at 20 °C; density: 890 kg m−3) and tap water. The ducts present sudden contractions from 50 mm to 40 mm i.d. and from 50 mm to 30 mm i.d., with contraction ratios of 0.64 and 0.36, respectively. About 200–320 tests were performed by varying the flow rates of the phases. Flow patterns were investigated for both the up- and downstream pipe in order to assess whether relevant variations of the flow patterns across the sudden contraction take place. Data were then compared with predictions of a specific correlation for oil–water flow and some correlations for gas–water flow. A drift-flux model was also applied to determine the distribution parameter

Measurement of the oil holdup for a two-phase oil-water flow through a sudden contraction in a horizontal pipe

Oil-water two-phase flow experiments were conducted in a horizontal duct made of Plexiglas to determine the holdup of oil by means of the quick closing valves technique, using mineral oil (viscosity: 0.838 Pa s at 20 °C; density: 890 kg m-3) and tap Water. The duct presents a sudden contraction, with contraction ratio of 0.64. about 200 tests were performed by varying the flow rates of the phases. Flow patterns were investigated for both the up- and downstream pipe. Due to the relatively high value of the contraction ratio, it was not observed any relevant variation of the flow patterns across the sudden contraction. Data were then compared with predictions of a specific correlation for oil-water flow and some correlations for gas-water flow. A drift-flux model was also applied to determine the distribution parameter. The results agree quite well with flow pattern visualization