687 research outputs found
Individual Contacts, Collective Patterns. Prato 1975-97, a story of interactions.
No full textThis article presents an agent-based model (ABM) of an Italian textile district where thousands of small firms specialize in particular phases of fabrics production. It is an empirical model because it reconstructs the communications between firms when they arrange production chains. In their turn, production chains reflect into the pattern of road traffic in the geographical areas where the district extends. It is a methodological model because it aims to show that ABMs can be used to reconstruct a web of movements in geographical space. ABMs are proposed as a tool for Hägerstrand’s “time-geography”.Industrial districts, Industrial clusters, Agent-based models, Prato
A statistical approach to discriminate between non-fallers, rare fallers and frequent fallers in older adults based on posturographic data
No full textBackground Identification of future non-fallers, infrequent and frequent fallers among older people would permit focusing the delivery of prevention programs on selected individuals. Posturographic parameters have been proven to differentiate between non-fallers and frequent fallers, but not between the first group and infrequent fallers. Methods In this study, postural stability with eyes open and closed on both a firm and a compliant surface and while performing a cognitive task was assessed in a consecutive sample of 130 cognitively able elderly, mean age 77(7)years, categorized as non-fallers (N = 67), infrequent fallers (one/two falls, N = 45) and frequent fallers (more than two falls, N = 18) according to their last year fall history. Principal Component Analysis was used to select the most significant features from a set of 17posturographic parameters. Next, variables derived from principal component analysis were used to test, in each task, group differences between the three groups. Findings One parameter based on a combination of a set of Centre of Pressure anterior-posterior variables obtained from the eyes-open on a compliant surface task was statistically different among all groups, thus distinguishing infrequent fallers from both non-fallers (P < 0.05) and frequent fallers (P < 0.05). Interpretation For the first time, a method based on posturographic data to retrospectively discriminate infrequent fallers was obtained. The joint use of both the eyes-open on a compliant surface condition and this new parameter could be used, in a future study, to improve the performance of protocols and to verify the ability of this method to identify new-fallers in elderly without cognitive impairment
Surgeon Island Granite: Implications for Regional Geological Evolution of Northern Victoria Land from Structural Observations and SHRIMP Zircon Dating
No full textDesign and validation of an adjustable large-scale solar simulator
No full textThis work presents an adjustable large-scale solar simulator based on metal halide lamps. The design procedure is described with regards to the construction and spatial arrangement of the lamps and the designed optical system. Rotation and translation of the lamp array allow setting the direction and the intensity of the luminous flux on the horizontal plane. To validate the built model, irradiance nonuniformity and temporal instability tests were carried out assigning Class A, B, or C for each test, according to the International Electrotechnical Commission (IEC) standards requirements. The simulator meets the Class C standards on a 200 × 90 cm test plane, Class B on 170 × 80 cm, and Class A on 80 × 40 cm. The temporal instability returns Class A results for all the measured points. Lastly, a PV panel is characterized by tracing the I–V curve under simulated radiation, under outdoor natural sunlight, and with a numerical method. The results show a good approximation
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