Embedding Fiber Bragg Grating Sensors in Carbon Composite Structures for Accurate Strain Measurement

Fiber Bragg grating (FBG) sensors written by femtosecond laser pulses in polyamide-coated low bending loss optical fibers are successfully embedded in carbon composite structures, following laminating and light resin molding processes which optimize the size of each ply to address esthetic, drapability, and structural requirements of the final components. The sensors are interrogated by a tunable laser operating at around 1.55 μm, and their response to temperature and strain variations is characterized in a thermally controlled chamber and by bending tests using suspended calibrated loads and a laser scanning system. Experimental results are in good agreement with simulations, confirming that the embedding process effectively overcomes potential issues related to FBG spectral distortion, birefringence, and losses. In particular, the effects of the composite material nonhomogeneity and FBG birefringence are investigated to evaluate their impact on the monitoring capabilities. A bimaterial mechanical beam model is proposed to characterize the orthotropic laminates, pointing out better accuracy in estimating the applied load with respect to the classical homogeneous beam model. A comparative analysis, performed on different instrumented carbon composite samples and supported by theory, points out the repeatability of the FBG sensors' embedding process and the effectiveness of the technology for real-time accurate strain measurement. Based on such measurements, damages and/or changes in local stiffness can be effectively detected, allowing for structural health monitoring (SHM) of composite structures for applications in specific industrial fields such as automotive and aerospace

Spanish Teachers\u27 Sense of Humor and Student Performance on the National Spanish Exams

Research suggests that second/foreign language teachers\u27 sense of humor is directly related to many outcomes for teachers and their students. This research investigates the relationship between the perceived sense of humor of in-service Spanish teachers\u27 (n = 102) and their students\u27 (n = 5,419) score on the National Spanish Exams using the affective filter hypothesis as a conceptual framework. Statistical analyses indicate that Spanish teacher sense of humor is related to student achievement on the exams. This research has implications for language teachers and teacher educators

Bistability versus Bimodal Distributions in Gene Regulatory Processes from Population Balance

In recent times, stochastic treatments of gene regulatory processes have appeared in the literature in which a cell exposed to a signaling molecule in its environment triggers the synthesis of a specific protein through a network of intracellular reactions. The stochastic nature of this process leads to a distribution of protein levels in a population of cells as determined by a Fokker-Planck equation. Often instability occurs as a consequence of two (stable) steady state protein levels, one at the low end representing the “off” state, and the other at the high end representing the “on” state for a given concentration of the signaling molecule within a suitable range. A consequence of such bistability has been the appearance of bimodal distributions indicating two different populations, one in the “off” state and the other in the “on” state. The bimodal distribution can come about from stochastic analysis of a single cell. However, the concerted action of the population altering the extracellular concentration in the environment of individual cells and hence their behavior can only be accomplished by an appropriate population balance model which accounts for the reciprocal effects of interaction between the population and its environment. In this study, we show how to formulate a population balance model in which stochastic gene expression in individual cells is incorporated. Interestingly, the simulation of the model shows that bistability is neither sufficient nor necessary for bimodal distributions in a population. The original notion of linking bistability with bimodal distribution from single cell stochastic model is therefore only a special consequence of a population balance model

Soilless greenhouse production of table grape under Mediterranean conditions

Soilless culture, widely used for vegetables, flowers and ornamental plants, can be an effective technique to grow table grape and to overcome several issues of the current vineyard production system (i.e. to facilitate variety change, no use of rootstock, extra-seasonal production and improved fruit quality). In this research two greenhouse experiments were carried out in Southern Italy, in a typical area for table grape cultivation, to determine the water consumption, vegetative growth, yield, and quality traits of table grapes grown in a soilless system. The first experiment was a simple comparison of two cultivars Cardinal and Victoria, whereas in the second experiment two cultivars (‘Black Magic’ and ‘Victoria’) were grown by using four nutrient solutions characterized by different macronutrient concentrations (100% Hoagland solution type vs 30%-reduced Hoagland: less N and P, or less N, P, Ca and Mg, or less N, P, K, Ca and Mg). In the first experiment, on average, at harvest the yield was 21.7 t ha-1, with a cluster weight of 419 g and 14.9 °Brix. In the second experiment, yield and cluster weight were, on average, 29.4 t ha-1 and 686 g, respectively, and were not affected either by nutrient solution composition or by the cultivar. In both experiments the mean cluster weight and all the organoleptic characteristics were above the European Commission rule n. 2137/2002 limits. These results show that the soilless culture provides table grapes with quality traits completely suitable for international market quality standards, and it is possible to reduce the nutrient concentration of the nutrient solution without negative effects on yield and quality of soilless table grapes