Experimental and numerical investigation of a meandering jet in shallow rectangular reservoirs under different hydraulic conditions

peer reviewedA central meandering jet in shallow rectangular reservoirs has been investigated numerically by the model WOLF2D, on the basis of experimental evidence of this type of flow field in two different setups at different scales. A sensitivity analysis has been conducted with respect to the main parameters of the model. The oscillation frequency of the transversal velocity and the characteristic Strouhal number have been calculated for different Froude numbers. A logarithmic relationship has been found between the Strouhal and the Froude numbers

IL RUOLO DELL¿HUNTINGTINA NELLA FISIOLOGIA DEL DIFFERENZIAMENTO NEURONALE E NELLA PATOLOGIA

Huntingtin (htt) is the 3,144 amino acid protein whose mutation causes Huntington\u2019s disease (HD). Mutant htt is toxic for brain neurons, but the mechanism leading to pathology is still far from being understood. Moreover, since loss of wild type (WT) htt contributes to pathogenesis, the study of htt\u2019s role and the effect of its depletion, in the central nervous system becomes important. In this Thesis we analyse complementarily the role of WT and mutant htt in physiological and pathological conditions. In the first part, it is described a novel role of WT htt during neural development. This field is still quite unexplored, and, even if the function of protein has been largely described during post-natal life (when HD onset occurs), there are recent evidences that also normal development could be altered in htt depletion condition. Specifically it has been investigated the role of htt in establishment and maintenance of neuroepithelial apico-basal polarity and, as a result, in the regulation of neural progenitors cell fate decision. We demonstrate that htt, through cooperation with polarity protein aPKC, contributes to regulation of polarity mechanism during early neurogenesis. In the second part of the Thesis it is described the establishment of a human in vitro model of HD, thanks to somatic cell reprogramming technology. We report the generation of a series of induced pluripotent stem (iPS) cells derived from several patients. HD-iPS cells have the potential to be differentiated to the neuronal population that degenerate during disease progression, holding the identical genetic information of the donor. Starting also from rare homozygous patient, and demonstrating mutation related enhanced lysosomal activity, our work is the first that describes a cohort of HD-iPS cells and their phenotypical characterization

prediction of mean and turbulent kinetic energy in rectangular shallow reservoirs

AbstractShallow rectangular reservoirs are common structures in urban hydraulics and river engineering. Despite their simple geometries, complex symmetric and asymmetric flow fields develop in such reservoirs, depending on their expansion ratio and length-to-width ratio. The original contribution of this study is the analysis of the kinetic energy content of the mean flow, based on UVP velocity measurements carried throughout the reservoir in eleven different geometric configurations. A new relationship is derived between the specific mean kinetic energy and the reservoir shape factor. For most considered geometric configurations, leading to four different flow patterns, the experimentally observed flow fields and mean kinetic energy contents are successfully reproduced by an operational numerical model based on the depth-averaged flow equations and a two-length-scale k- turbulence closure. The analysis also highlights the better performance of this depth-averaged k- model compared to an algebraic turbu..

Neuropotent self-renewing neural stem (NS) cells derived from mouse induced pluripotent stem (iPS) cells

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Adaptation of NS cells growth and differentiation to high-throughput screening-compatible plates

Peer reviewedPublisher PD

Experimental study of velocity fields in rectangular shallow reservoirs

Velocity fields in rectangular shallow reservoirs with different length-to-width and expansion ratios were investigated in an experimental study, to evaluate the effect of geometry on the flow field. A wide range of combinations of these two non-dimensional geometric parameters were tested at constant hydraulic conditions. Ultrasound velocity profilers were used to measure the horizontal velocity components across the entire reservoir surface, allowing for the visualization of streamlines and of the instantaneous and average velocities. Five different types offlow patterns were identified, depending on the values of the length-to-width ratio and expansion ratio of the reservoir. Asymmetrical flow patterns were found to develop for certain combinations of these geometric parameters despite the perfect reservoir symmetry. A critical comparison of these new experimental results with those of other works is provided

Il progetto SISTER

Il CILEA in collaborazione con il Politecnico di Milano sta realizzando un sistema informativo, denominato SISTER (Sistema Informativo Statistico Territoriale), che ha lo scopo di mettere in linea sulla rete informatica universitaria il maggior numero di archivi statistici relativi all'Italia e ai vari paesi europei per poter compiere analisi di realtà specifiche sulle quali si opera. Il sistema informativo propone un ambiente di lavoro particolarmente user-friendly ed è integrato con uscite di tipo grafico per meglio comprendere trends e fenomeni altrimenti difficilmente percepibili. L'architettura del sistema è di tipo client/server

Discussion “Experimental study of velocity fields in rectangular shallow reservoirs”, Reply by the authors

The authors present the results of a new experimental study to improve the flow classification in rectangular shallow reservoirs. Although previous papers have paved the way for the classification (Dewals et al. 2008, Dufresne et al. 2010), the authors are complemented for the detailed flow-field measurements conducted for a high number of reservoir geometries, complementing the previous observations based on Large Scale Particle Image Velocimetry (Dewals et al. 2008). The studied rectangular reservoirs have a length L and a width B, and the width of the inlet and outlet channels is b. The authors refer to a non-dimensional shape parameter T = L/(B − b)0.6/b0.4, which is actually a multiple of the shape parameter L/[(B − b)/2]0.6/b0.4 = 20.6T ≈ 1.516 T as defined by Dufresne et al. (2010). For the tested hydraulic conditions, the authors report that for T 4.48, the flow is asymmetric, with a transition zone between the two limits, corresponding to “unstable” flow pattern. Repeated tests under similar conditions lead alternately to a symmetric or an asymmetric flow field. It is intended below to shed light on this transition zone using 2D numerical simulations. The authors state that the flow in the transition zone is sensitive to so-called “external perturbations”, whereas we argue that the flow is particularly influenced by the initial test conditions. Using a particular post-processing of the computed flow fields, a hysteresis effect is detected

Human Pluripotent Stem Cell Differentiation into Authentic Striatal Projection Neurons

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