87,936 research outputs found
Developing innovative pedagogical scenarios around dynamic models for a first year mechanics course
No full textAssessment of a Dual-Wavelength Compensation Technique for Displacement Sensors Using Plastic Optical Fibers
No full textThe paper analyzes the performance of a dual-wavelength technique devised to compensate power fluctuations in intensity-modulated plastic optical fiber sensors, which were specifically conceived for the measurement of displacements in industrial and civil applications. These sensors retrieve the displacement from the variation of the attenuation along the light path and use two signals at different wavelengths to compensate for the effects of parasitic quantities, such as temperature and strains along the fiber. The theoretical behavior of the compensation technique is presented, and the results of experiments carried out with different combinations of signal wavelengths and plastic fibers are reported. The experimental setup has proved that, by proper choice of the compensation signal wavelength, it is possible to monitor displacements in the range (0 to 10) mm, even for low received power and under severe perturbation conditions, thus significantly improving the long-term stability of the sensor
Formation of buried conductive micro-channels in single crystal diamond with MeV C and He implantation
No full textAs demonstrated in previous works, implantation with a MeV ion microbeam through masks with graded
thickness allows the formation of conductive micro-channels in diamond which are embedded in the
insulating matrix at controllable depths [P. Olivero et al., Diamond Relat. Mater. 18 (5–8), 870–876 (2009)].
In the present work we report about the systematic electrical characterization of such micro-channels as a
function of several implantation conditions, namely: ion species and energy, implantation fluence. The
current–voltage (IV) characteristics of the buried channels were measured at room temperature with a two
point probe station. Significant parameters such as the sheet resistance and the characteristic exponent (α)
of the IV power-law trend were expressed as a function of damage density, with satisfactory compatibility
between the results obtained in different implantation conditions
"Sistemi di monitoraggio basati su imbarcazioni senza pilota (Unmanned Sea Vehicle - USV) per il monitoraggio dei porti; sperimentazione a terra e concetti derivati per applicazioni terrestri)"
No full textA novel luminescent bifunctional POSS as a molecular platform for biomedical applications
No full textA novel luminescent polyhedral oligomeric silsesquioxane (POSS) containing in the structure a fluorescein derivative molecule and a carboxylic functionality, suitable to anchor different organic compounds (dyes, markers, drugs, contrast agents,...), was successfully synthesized and characterized in this manuscript by a multidisciplinary approach. An emission enhancement of the dye of ca. four times was found after reaction with POSS, rendering this new hybrid compound a promising contrast agent for optical imaging. In vitro tests on tumoral HeLa cells demonstrated that the luminescent POSS (namely POSS-F), here described, is able to be taken up in the cell cytosol by an efficient and selective process. Its high chemical versatility and peculiar properties could render this novel bifunctional POSS a molecular platform for biomedical applications
Providing the motivation to prove in a dynamic geometry environment
No full textThe use of dynamic geometry software may provide opportunities to improve the teaching and learning of mathematical proof within the context of plane geometry. Yet, it seems, if the approach to proving continues to emphasise a standardised linear deductive presentation, little improvement in student conceptions may result. This paper considers the design of geometrical tasks that could provide the motivation to prove
Sequential versus concomitant therapy for Helicobacter pilori infection in children: a pilot study
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