223 research outputs found
Numerical Heat Transfer Analysis of a Test Section with Film Cooling - Shock Wave Interaction
No full textIl paper tratta dell'interazione tra fluido refrigerante e urti obliqui
Heat Transfer Prediction of Film Cooling in Supersonic Flow
No full textL'articolo tratta dell'interazione urto/refrigerante.
The article deals with the shock/coolant interaction
Neurophysiological and neuroradiological findings in asymptomatic HIV seropositive subjects
No full textCan tide dominance be inferred from the point bar pattern of tidal meandering channels?
No full textWe performed 2-D numerical simulations of flow and bed topography in a channel consisting of a sequence of tidal meanders connected to a tidal sea at one end and closed at the other end. Our main goal was to investigate whether the location of point bars relative to the bend apex is correlated with the character of the local flow field, i.e., its flood or ebb dominance. Validation of the model was achieved performing a comparison with results of laboratory observations. Simulations did reproduce the observed evolution of the laterally averaged bed profile toward an equilibrium configuration characterized by the classical landward aggrading trend typical of straight tidal channels with the formation of a shore at the landward end. The presence of meanders led to small amplitude spatial oscillations of the profile on the meander scale. The bar pattern developed when the morphology was far from equilibrium, such that the sediment transport was sufficiently intense to drive significant morphodynamic perturbations. Numerical results did show conclusively that the key factor controlling the phase of the point bar pattern relative to curvature is the flood- or ebb-dominant character of the basic flow field. More precisely, ebb/flood dominance led to point bars located seaward/landward relative to the bend apex. Moreover, two almost symmetrical long lobes that trailed away from the meander apex in both the ebb and flood directions formed in the transition region where the flow field shifts from flood into ebb dominant
Diplodia sapinea: the main fungal species involved in the colonization of pine shoots in Italy
No full textDamage to various forest tree species caused by Diplodia sapinea has been reported in Italy since the early 20th century. However, until recently, systematic characterization of this microorganism, based on DNA sequence data, has been limited with only a general description of the fungus in the majority of the reports. To address this and provide a more accurate identification of Diplodia species associated on pine in Italy, we examined a total of 88 Botryosphaeriaceae isolates obtained from symptomatic and asymptomatic material from different
hosts located in different geographical regions of Italy. Using molecular analysis, we were able to identify 67 isolates of D. sapinea and eight isolates of D. seriata. Diplodia sapinea was dominant on P. nigra shoots and was also detected on P. halepensis, P. pinea, P. pinaster, P. radiata and P. sylvestris, while D. seriata and other Botryosphaeriaceae appeared to be only occasionally present on shoots. The remaining 13 isolates represented nine different Botryosphaeriaceae species, occurring at low levels. Analysis of molecular variance (AMOVA) based on DAMD-PCR profiles detected low significant differences among D. sapinea isolates from the different sampling areas throughout Ital
On the equilibrium profile of river beds
No full textDespite the wide spectrum of perturbations of flow and sediment transport experienced by rivers as a result of hydrologic variations, the paradigm of morphodynamic equilibrium has long been present in the geomorphological literature where it is traditionally associated with the semiempirical notion of formative discharge, whereby the unsteady forcing is taken as morphologically equivalent to some effective steady forcing. Here we investigate the mechanisms responsible for maintaining a quasi-equilibrium bed profile of a river reach sufficiently short to have no significant tributary inputs. More importantly, we assume the channel banks to be fixed, hence, the case we have in mind is that of rivers protected by levees which cannot respond to hydrologic forcing by changing their width like natural rivers. Employing a 1-D model of river morphodynamics, we first determine the equilibrium profile of the river reach for given steady forcing conditions and discuss the capability of this approach for interpreting bed profiles observed in the field by applying it to the terminal reach of the Magra River, Italy. Field observations turn out to be reasonably well fitted by the equilibrium profile associated with a steady effective discharge, which however differs from the typical formative discharge (mean annual flood) for natural channels with erodible banks. Finally, we clarify how fluctuations of the hydrodynamic forcing associated with the recorded historical sequence of hydrologic events of variable intensities have acted to maintain the river equilibrium
Building and sharing teacher professional identity in virtual communities
No full textThe main objective of the present research is the elaboration and validation of online workshop models aimed at the university training of primary school teachers. The research was carried out over two year period (the 2005-06 and 2006-07 academic years) in the University of Padova. Two different types group of students were involved, pre-service and the in-service (professional beginner and advance beginner) teacher students. Collaborative casework activities were offered to all students who attended online workshops with direct reference to Communities of Inquiry by David R. Garrison and Terry Anderson (2003). The research was based on integrated mixed methodology: multi strands multi methods (Teddlie and Tashakkori, 2005). The data, provided from pre-post individual activities (profile protocols) and forum’s activities (forum protocols), was analysed using quantitative approaches (specificity and correspondence analyses etc.) and quantitative-qualitative approach (protocols of forums) using categories of David R. Garrison and Terry Anderson (2003; Garrison et al, 2006), Helen L. Harrington (Harrington et al, 1996), Richard F. Bales (1950; 1970) revisited and analysed by new “integrated” SNA model, and narrative interviews made with selected beginners and advanced-beginners teachers students. The results obtained confirm effectiveness of online workshop models only for student and beginner teachers, and also a tendency towards a functional fixedness and self-reference of in service teacher students, especially in advanced teachers students. The positive results of narrative interviews carried out also confirmed an increased awareness and deeper comprehension of personal and professional identity in the involved subjects. These results lead us to consider the prospect of a new model of teacher education that may be promising especially for the advanced-beginner teachers and other levels of competent or expert teachers, categories which have proven to be the most resistant to professional identity conceptual changes
Situation with ash in Italy: stand characteristics, health conditions, ongoing work and research needs
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