1,782 research outputs found
Un corpo che prende forma: l'ordine di successione dei trattati ippocratici dall'età ellenistica fino all'età bizantina
No full textLE EQUAZIONI DI TERZO E QUARTO GRADO.
No full textIn questo articolo si dà una trattazione a livello "elementare" per la risoluzione delle equazioni di terzo e quarto grado
SPAZI VETTORIALI E MATRICI.
No full textIn questo articolo si danno le nozioni di base sugli spazi vettoriali reali e sulle matrici
Historic masonry monitoring by motion magnification analysis
No full textVibration monitoring of historic structures in urban environment is a relevant issue for health survey and early damaging detection in sustainable and enhanced resilient cities. This study explores the potentialities of vibration monitoring by Motion Magnification Analysis. Motion magnification acts like a microscope for motion in video sequences, but affecting only some groups of pixels. The motion magnification uses the spatial resolution of the video-camera to extract physical properties from images to make inferences about the dynamical behaviour of the object, e.g. to visualize at least the first mode shape, no matter its dimensions, since any point on the surface of the object can be considered a virtual sensor. Recently, a number of experiments conducted on simple geometries like rods and other small objects, as well as on bridges, showed the reliability of this methodology compared to accelerometers and lasers. Researchers have been also very interested in assessing the method’s feasibility, since conventional devices are surely more precise, but more expensive and much less practical. In this paper, we give an introduction to MMA and describe its application to the analysis of two full-scale historic masonry walls tested on shaking tables. This is an interesting point, because the size of tested walls is larger than usual small experimental set-ups implemented in MMA testbed until now. Results showed that MMA allowed a visual identification of fractures in advance. Moreover, we performed some conventional calculation for modal analysis of the walls, such as FRF and PSD, on MMA output data. Though the used equipment (camera, tripod and lighting) was of low quality, in order to test the methodology in an unfavourable environment with very high data noise, the estimate of the first modal frequency showed a good agreement with modal analysis by a more conventional optical system used as reference. © 2017 WIT Press
Atteggiamento dei consumatori nei confronti dell’evoluzione del sistema agro-alimentare: L’introduzione di alimenti geneticamente modificati
No full textL’atteggiamento dei consumatori nei confronti di alimenti che contengono OGM o sono
ottenuti da OGM e gli alimenti che contengono ingredienti ottenuti da OGM (di seguito designati
complessivamente con l’espressione "alimenti geneticamente modificati" o “alimenti GM”)
rappresenta un tema di grande attualità per il sistema agro-alimentare europeo.
Le esigenze dei consumatori, caratterizzate da una crescente importanza assegnata alle
caratteristiche sia dei processi produttivi sia degli alimenti finali, impongono un’ampia ed attenta
analisi dei possibili effetti sui comportamenti di acquisto che l’introduzione di alimenti GM nel
sistema agro-alimentare potrebbe generare.
La diffusione della coltivazione di varietà di piante GM, principalmente in Paesi extraeuropei
(USA, Canada ed Argentina), e l’immissione sul mercato mondiale di prodotti OGM
destinati anche all’alimentazione umana, ha generato accesi dibattiti in Europa pro e contro
l’adozione di questa nuova tecnologia, per i possibili effetti negativi per i consumatori e
sull’ambiente.
L’UE sin dai primi anni 90 ha cercato di definire una normativa sugli OGM capace di
garantire la protezione della salute dei cittadini e dell'ambiente e al tempo stesso creare un mercato
unificato della biotecnologia.
L’obiettivo di questo lavoro è di valutare, alla luce del quadro normativo vigente in materia
di alimenti GM, l’atteggiamento dei consumatori nei confronti di alcune caratteristiche del sistema
agro-alimentare (di seguito designati come “attributi”) e in particolare dell’introduzione nei
mercati finali di alimenti geneticamente modificati.
Per valutare l’atteggiamento dei consumatori, in termini quantitativi oltre che qualitativi, si
intende misurare la loro disponibilità a pagare (DAP) pro o contro delle variazioni
(presenza/assenza o aumento/diminuzione) degli attributi considerati rispetto allo status quo,
utilizzando la metodologia del choice modelling.
Si tratta, in altri termini, del tentativo di fornire delle risposte alle seguenti domande:
l’avversione dei consumatori nei confronti degli alimenti OGM è indipendente dal livello di sconto
di cui i consumatori potrebbero beneficiare per i prodotti alimentari contenenti OGM? Ovvero, le
problematiche ambientali ed etiche che muovono i cittadini ad essere contro le biotecnologie
applicate alla produzione di alimenti sono negoziabili? Qual è l’importanza relativa, per i
consumatori, della tecnologia GM rispetto ad alcune altre variabili del sistema agro-alimentare? La
normativa vigente che disciplina l'immissione in commercio di prodotti GM e stabilisce norme per
l’etichettatura dei prodotti destinati al consumatore finale è sufficiente a garantire i consumatori
oppure esistono spazi per prodotti, quali gli OGM-free, che si ispirano al principio della tolleranza
zero?
La possibilità di immettere sul mercato prodotti GM-free dipende dalla DAP dei
consumatori per questo tipo di prodotti. Pertanto, valutare la DAP per gli alimenti OGM-free
fornirebbe indicazioni utili circa l’esistenza di opportunità di mercato per le imprese che intendono
perseguire questa strategia di differenziazione di prodotto. L’analisi potrebbe fornire, inoltre,
indicazioni utili anche per quanto concerne nuove azioni di politica per il comparto agroalimentare
orientate al soddisfacimento delle attese dei consumatori
Finite element validation using displacement data from shake table tests within a virtual laboratory
No full textThe present paper shows an interactive and iterative methodology for the validation of finite element models with experimental data acquired during shaking table tests using a three-dimensional motion capture system. Such a system can detect the complete motion of up to hundreds of retro-reflective markers placed on the tested structure. The markers trajectories, reconstructed by spatial triangulation of camera rays, are processed with a dedicated displacement data processing (DDP) procedure to extract motion parameters. In the followed methodology a preliminary finite element analysis (FEA) is performed to identify the critical points of the model. Then such a FEA is integrated with the displacement data processed by DDP, focusing on the points where the strain energy concentration is most dangerous and allowing the numerical model validation. The displacements of selected markers are imposed at the corresponding nodes of the finite element model, while the displacements of the remaining nodes of the finite element analysis are compared with the corresponding markers on the real structure. In order to calibrate the model during the experimental investigation, the finite element model is updated at each step of the test sequence exploiting the hardware resources available in CRESCO, the ENEA HPC system. © Civil-Comp Press, 2014
Simulation and measurement of quasi-optical multipliers
No full textThe lumped-element finite-difference time-domain method is used to analyze quasi-optical multipliers based on diode loaded slot antennas. The method is validated firstly for a passive microstrip-fed structure then for the diode loaded case in both small- and large-signal regimes. The diode model is separately validated using a series diode mounted on a microstrip line. Input return loss and radiation patterns show good agreement with measurements and the concept of effective conversion loss is introduced and results show reasonable agreement between measurement and simulation. A new diode arrangement is introduced where dual offset diodes are placed in the slot instead of the conventional central diode. The diode position can then act as an extra design parameter. The performance of the two structures has been compared; currently best performance is still obtained for the central-diode structure. Finally, a fully quasi-optical structure is simulated with plane-wave excitation. Central and dual-diode structures are again compared and the diode position and input plane-wave field strengths are optimized. Slot voltage distributions, radiation patterns, and effective quasi-optical conversion losses are presente
The gynaecological and nosolgical treatises of the Corpus Hippocraticum: the tip of an iceberg
No full textGravity and gravidity : will microgravity assist pregnancy?
No full textDuring the third trimester of pregnancy, exercise, deep ventilation and supine position may be particularly uncomfortable for pregnant women. Reduction of fetal weight by a microgravity environment may relieve some of this discomfort. This study assessed, by means of heart rate variability (HRV), the cardiovascular adaptation to the supine posture, to relaxing respiratory exercises (deep slow breathing) and to mild and moderate lower limb exercises in pregnant women, both in a dry environment and during a head-out water immersion, which mimics microgravity. Six third-trimester pregnant women (31±3 years; 67.8±8.3 kg; 163±3 cm; gestational age 26±6 weeks) were enrolled. Five-minute series of beat-to-beat RR intervals were recorded by a heart rate monitor in basal (B) state (on a separate day, comfortably sitting in a quiet room, 22° C) and in 2 different environments (G, gym, 22° C; W, water immersion at 34° C), on separate days, in 5 experimental conditions for each environment: (1) resting supine; (2) during upright mild lower limb exercise; (3) during upright moderate lower limb exercise; (4) during controlled deep ventilation (breathing rhythm, 0.1 Hz); (5) during controlled breathing (supine). Compared to B state, HR increased slightly in all experimental conditions in both G (+16%) and W (+8%) environments, whereas blood pressure did not. LF/HF ratio, a marker of sympathovagal balance, increased significantly during G at rest (5.0±2.4, p<0.05) but not in W at rest (2.7±1.5), and further increased during mild and moderate exercise in both G and W. During slow breathing in both environments (conditions 4 and 5), LF/HF paradoxically increased compared to B. Finally, LF/HF significantly increased (6.5±2.6, p=0.01) during ventilation in supine position, but only in G environment. Only HF decreased in both G_rest (-46.2%, p<0.05) and W_rest-24.6%, p<0.05) compared to B state, whereas LF was almost unchanged. Immersion in thermoneutral water, which mimics microgravity, produces some positive effects on the autonomic adaptation to different manoeuvres (supine position, exercise, deep slow ventilation) in third-trimester pregnant women. These effects are especially relevant in the assumption of supine posture, suggesting that microgravity will probably relieve the symptoms of aorto-caval compression produced by the fetus burden
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