177,387 research outputs found
Inclusion: Looking for a new design approach for the development of the city for all
No full textAn interesting definition given to sustainability is “for everybody, forever”. Unfortunately, if we consider Italian cities, although many of them are UNESCO World Heritage Sites, they can not fit in this definition. First of all, in a world with aging population and where disability is no longer the exception, cities still present too many physical barriers that prevent people from using public space. Secondly cities have not been able to respond to the dynamism of migration flows and the progress of multiculturalism, causing episodes of inequality and social decay. Although these issues have always been at the center of the attention and the assumption underlying any design process is the identification and satisfaction of users’ needs, there are numerous project interventions that in recent years are not able to provide appropriate responses to these needs. For this reason, in particular for the city as the place of daily activities and social relations, it’s necessary a transition to a new design approach which ensures a fully inclusive view of the project and the effective well-being of people. Through the research it has been possible to define this new inclusive approach, which is primarily based on a cognitive phase to know users, their real needs and expectations. Then it’s necessary to define the tools for the development of a city for all, to be achieved through integrated design solutions, fitting to the different users’ skills. It’s also important to recognize the need for management actions to work alongside the architectural solutions to ensure their real effectiveness. In conclusion, this new design approach allows to obtain many benefits, from social to economic ones, but above all to rediscover the role of the city on the quality of people’s lives, especially in the Italian contest
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Simulation of transport through a cavity defined in graphene with electrostatic lithography
No full textWe present numerical simulations that we have performed with the aim of interpreting the results of the transport measurements that we have recently obtained on a graphene device in which a cavity-shaped potential, orthogonal to the transport direction, had been induced with electrostatic lithography. The resistance of the sample has been computed for a broad spectrum of possible potential configurations, both as a function of the backgate voltage, and of the position of a biased probe scanned at a fixed distance from the graphene sheet. The comparison between the experimental measurements and the numerical results have allowed us to determine the details of the potential profile in the device
Immediate Implant placement after removal of a failed implant: A clinical and histological case report
No full textThe purpose of this study was to evaluate the clinical success of an implant placed immediately after the explantation of a fractured blade implant. A healthy 58-year-old male nonsmoker presented with a fractured blade implant that had been subjected to biomechanical overload. A new blade implant was placed immediately after the removal of the fractured one. The new implant was placed with a composite graft of collagen gel and corticocancellous porcine bone and covered with a bioabsorbable membrane. Radiographic evaluation at 6 months postoperation showed complete bone healing. No residual bone defect was observed or probed during the uncovering phase; moreover, no mobility, pain, suppuration, or presence of peri-implant radiolucency were observed at the second-stage surgery
Identification of a c-fos-induced gene that is related to the platelet-derived growth factor/vascular endothelial growth factor family
No full textUsing a mRNA differential screening of fibroblasts differing for the expression of c-fos we isolated a c-fos-induced growth factor (FIGF). The deduced protein sequence predicts that the cDNA codes for a new member of the platelet-derived growth factor/vascular endothelial growth factor (PDGF/VEGF) family. Northern blot analysis shows that FIGF expression is strongly reduced in c-fos-deficient cells. Transfection of exogenous c-fos driven by a constitutive promoter restores the FIGF expression in these cells. In contrast, both PDGF and VEGF expression is unaffected by c-fos. FIGF is a secreted dimeric protein able to stimulate mitogenic activity in fibroblasts. FIGF overexpression induces morphological alterations in fibroblasts. The cells acquire a spindle-shaped morphology, become more refractive, disorganized, and detach from the plate. These results imply that FIGF is a downstream growth and morphogenic effector of c-fos. These results also suggest that the expression of FIGF in response to c-fos activation induces specific differentiation patterns and its aberrant activation contributes to the malignant phenotype of tumors
The Effects of Swirling Flows in Entropy Wave Convection Through High-Pressure Turbine Stage
No full textFirst stages of aeronautical high-pressure turbines are subjected to significant inlet distortions generated by the combustor system. These disturbances are characterized by velocity and temperature fluctuations convected downstream by the flow. Such perturbations are commonly defined as vorticity and entropy waves and interact with the turbine stages affecting the aerodynamic performance, the heat exchange, and generating indirect noise. Moreover, the presence of a swirling flow highly influences the convection and migration of the entropy wave and thus its interaction with the stage. This article presents an in-depth study of the impact of the swirling flows on the entropy wave evolution by means of experimental campaigns and numerical simulations. Experimental campaigns have been carried out at Politecnico di Milano where a high-pressure turbine rig was equipped with a novel combustor simulator able to generate entropy waves and swirl profiles. Numerical simulations have been performed at the University of Florence by applying time accurate simulation schemes, including incoming disturbances, implemented in the CFD TRAF code. Two different entropy waves (featuring frequencies of 10 and 110 Hz) injected in a counterclockwise swirling region at mid-span have been analyzed at two clocking positions: passage aligned and vane aligned. An excellent agreement is found between experimental acquisitions and numerical results: both show an important reduction of the temperature fluctuations through the stage and highlight the effect of the swirling profile on secondary flows and blade wakes. The extensive comparison reported in this article validates the numerical approach (based on unsteady simulations postprocessed by a dedicated filtering technique), which has been further applied to study the impact of swirling flows with an opposite rotation (clockwise). The broad numerical investigation combined with the extensive experimental campaign leads to a deeper understanding of the aerodynamic, thermal, and acoustic implications related to entropy wave evolution in a swirling flow, highlighting the interaction phenomena and suggesting how to minimize the impact of entropy waves by comparing the results of the different injection positions and swirling flow directions
Huge Conductance Peak Caused by Symmetry in Double Quantum Dots
No full textWe predict a huge interference effect contributing to the conductance through large ultraclean quantum dots of chaotic shape. When a double-dot structure is made such that the dots are the mirror image of each other, constructive interference can make a tunnel barrier located on the symmetry axis effectively transparent. We show (via theoretical analysis and numerical simulation) that this effect can be orders of magnitude larger than the well-known universal conductance fluctuations and weak localization (both less than a conductance quantum). A small magnetic field destroys the effect, massively reducing the double-dot conductance; thus a magnetic field detector is obtained, with a similar sensitivity to a SQUID, but requiring no superconductors
Computational and experimental study of the unsteady convection of entropy waves within a high pressure turbine stage
No full textThis paper describes the transport and the interaction of pulsating entropy waves generated by combustor burners within a high pressure turbine stage for aeronautical application. Experiments and Computational Fluid Dynamics (CFD) simulations were carried out in the context of the European Research Project RECORD. Experimental campaigns considering burner-representative temperature fluctuations (in terms of spot shape, fluctuation frequency and total temperature variation percentage) injected upstream of an un-cooled high-pressure gas turbine stage have been performed in the high-speed closed-loop test-rig of the Fluid Machine Laboratory (LFM) of Politecnico di Milano (Italy). The pulsating entropy waves are injected at the stage inlet in streamwise direction at four different azimuthal positions featuring a 7% over-temperature with respect to the main flow with a frequency of 90 Hz. Detailed time-resolved temperature measurements (in the range of 0–200 Hz) upstream and downstream of the stage, as well as in the stator–rotor axial gap were performed. Time-accurate CFD simulations with and without entropy fluctuations imposed at the stage inlet were performed with the TRAF code, developed by the University of Florence. A numerical post-processing procedure, based on the DFT (Discrete Fourier Transform) of the conservative variables has been implemented to extract the low frequency content connected to the entropy fluctuations. Measurements highlighted a significant attenuation of the entropy wave spot throughout their transport within the stator channel and their interaction with the rotor blade rows, highly depending on their injection azimuthal position. Simulations show an overall good agreement with the experiments on the measurement traverses, especially at the stage outlet. By exploiting the combination of experiments and simulations, the aerodynamic and thermal implications of the temperature fluctuation injected upstream of the stage were properly assessed, thus allowing suggest useful information to the designer. The comparison with the experiments confirms the accuracy of the CFD method to solve the periodic, but characterized by a low frequency content event, associated with the entropy wave fluctuation
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
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