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51.
Painted glass magic lantern plates from the Museo Nazionale del Cinema, Torino (Italy), were studied using mid-infrared (mid-IR) fibre-optic reflectance spectroscopy (FORS), a non-invasive technique, to test its potential for the identification of the types of binding media used in the paints. Gum, oil and resin media were identified on the plates and the amounts of these media varied from place to place; the discovery of these media correlate well with the literature on magic lantern plate preparation and painting. The spectra collected are reported uncorrected and also with the fingerprint region corrected with the Kramers–Kronig correction, which corrects distorted peaks caused by specular reflections. 相似文献
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The relationship between student study time allocation and examination performance is little understood. We model the allocation of student time into formal study (lectures and classes) and self study and its relationship to university examination scores using a stochastic frontier production function. This case study uses unique time budget data and detailed personal records from one university in Spain. The results suggest that, within the formal system of teaching in Spain, both formal study and self study are significant determinants of exam scores but that the former may be up to four times more important than the latter. We also find that self study time may be insignificant if ability bias is corrected for. 相似文献
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Oscar Chiantore Chiara Riedo Tommaso Poli Giancarlo Cotrufo Peter Hohenstatt 《文物保护研究》2018,63(5):58-63
ABSTRACTThe first step in preservative measures for artworks in airtight showcases is the exclusion of outgassing from construction materials or, at least, limitation of the emissions to a minimum acceptable level if the volatile organic compounds (VOCs) generated may be qualified as harmless. Once it is ascertained that the objects in the showcases are responsible for VOC emissions, a step forward becomes necessary, implying showcase ventilation with air flowing through active sorbent materials. Solid phase micro-extraction (SPME) followed by GC separation and MS identification has been applied for checking the outgassing characteristics of different types of materials used for the construction of airtight showcases, and the method was found particularly attractive in terms of speed and sensitivity, suitable for measurements in presence of low-emitting materials. Sampling could also be done in the case interiors, thus making possible detection and recognition of emissions from art objects within a case. A comprehensive preventive conservation scheme has been further devised by means of active air circulation within the showcase and functional sorbent materials along the flow, for complete suppression of gaseous compounds. Control of the compounds in the air flow and of their filtration efficacy was achieved by direct sampling, also using SPME fibers. Continuous monitoring of the air quality in the showcases has been developed with insertion of a photoionization detector capable of detecting the VOCs in the air by inducing molecular ionization, and measuring the generated photocurrent. The system is not selective, but gives the total concentration, reaching ppb sensitivity with high-quality data. In addition it includes temperature and humidity sensors, making the whole a useful instrument for environment control. 相似文献
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Kate Parker Anna Timperio Jo Salmon Karen Villanueva Helen Brown Irene Esteban-Cornejo Veronica Cabanas-Snchez Jos Castro-Piero David Snchez-Oliva Oscar L. Veiga 《运动与健康科学(英文)》2021,10(4):447
BackgroundChildren and adolescents can be distinguished by different typologies (clusters) of physical activity and sedentary behavior. How physical activity and sedentary behaviors change over time within different typologies is not known. This study examined longitudinal changes in physical activity and sedentary time among children and adolescents with different baseline typologies of activity-related behavior.MethodsIn this longitudinal study (3 annual time points) of children (n = 600, age = 9.2 ± 0.4 years (mean ± SD), 50.3% girls) and adolescents (n = 1037, age = 13.6 ± 1.7 years, 48.4% girls), participants were recruited in Spain in 2011–2012. Latent class analyses identified typologies based on self-reported screen, educational, social and relaxing sedentary behaviors, active travel, muscle strengthening activity, and sport at baseline. Within each typology, linear mixed growth models explored longitudinal changes in accelerometer-derived moderate-to-vigorous physical activity and sedentary time, as well as time by class interactions.ResultsThree typologies were identified among children (“social screenies”, 12.8%; “exercisers”, 61.5%; and “non-sporty active commuters”, 25.7%) and among adolescents (“active screenies”, 43.5%; “active academics”, 35.0%; and “non-sporty active commuters”, 21.5%) at baseline. Sedentary time increased within each typology among children and adolescents, with no significant differences between typologies. No changes in physical activity were found in any typology among children. In adolescents, physical activity declined within all typologies, with “non-sporty active commuters” declining significantly more than “active screenies” over 3 years.ConclusionThese results support the need for intervention to promote physical activity and prevent increases in sedentary time during childhood and adolescence. Adolescents characterized as “non-sporty active commuters” may require specific interventions to maintain their physical activity over time. 相似文献
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Oscar Jimenez-Castellanos 《The Urban Review》2010,42(4):351-371
This study examines the relationship between educational resources (fiscal, personnel and facilities) and school achievement
within a large urban/suburban elementary school district. A sequential mixed methods approach reveals inequitable resource
allocation trends and patterns between schools within a school district by producing different student outcomes. The educational
resources positively correlated to higher school achievement are: higher teacher salaries, newer schools, more multi-purpose
space per pupil and less portable classrooms. Without question, White students receive more of these resources than Latino
students, low-income students and English Language learners. This study also conducts a multiple comparative case study analysis
comparing between Title I and non-Title I schools, within Title I schools and within non-Title I schools. The study contains
policy and practice implications to improve opportunity and school achievement in urban/suburban school districts. 相似文献
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Research on social networks and innovation emphasizes that individuals spanning structural holes and crossing institutional boundaries have more opportunities for knowledge recombination and innovation involvement. However, transforming the potential knowledge and resources available through personal networks to attain innovation can be difficult for the focal individual. Using an ego-network approach, this study examines whether and to what extent an individual strategic orientation to cooperation (i.e. tertius iungens) contributes to strengthening the relation between two personal network properties (structural and institutional separation) and involvement in innovation. Our analysis is conducted in the context of biomedicine, where research networks are particularly relevant for science and innovation achievements. Our findings advance social network theory by decoupling social network mechanisms from individual strategic networking behavior as factors influencing knowledge generation processes. Results also provide original evidence on an overlooked phenomenon: the moderating role of a tertius iungens orientation in the relationship between multiple social network properties and innovation. Finally, our research sheds new light on the distinct sources of knowledge recombination in networks and the role of individual networking strategies to facilitate mobilization of resources for innovation. 相似文献