Provitamin A biofortification of crop plants: a gold rush with many miners

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Plant carotenoids: genomics meets multi-gene engineering

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Bayesian estimate of the degree of a polynomial given a noisy data sample

A widely used method to create a continuous representation of a discrete data-set is regression analysis. When the regression model is not based on a mathematical description of the physics underlying the data, heuristic techniques play a crucial role and the model choice can have a significant impact on the result. In this paper, the problem of identifying the most appropriate model is formulated and solved in terms of Bayesian selection. Besides, probability calculus is the best way to choose among different alternatives. The results obtained are applied to the case of both univariate and bivariate polynomials used as trial solutions of systems of thermodynamic partial differential equations.Comment: 10 pages, 5 figures, submitted to Metrologi

Solar rejection in laser based underwater communication systems

This article provides a numerical study of the expected improvements in an underwater optical system given by a single-mode laser diode operating within a Fraunhofer line in a coastal water type. The system performance is examined for a silicon PIN direct-detection receiver in the euphotic zone. The solar irradiance, modelled as white noise, is evaluated when using a lithium niobate interference and a birefringent filter with different field-of-view (FOV) characteristics in a clear sky situation. The results of this analysis show the inverse dependence of the signal-to-noise (SNR) on the FOV, along with the significant improvement in the receiver sensitivity given by a narrow optical bandpass filter (OBPF)

Laser Based Underwater Communication Systems

We report on recent progress in the field of visible light communications including direct modulation of blue laser devices at data rates beyond 10 Gbit/s, and the transmission of 2.5 Gbit/s OOK data through water. We also discuss the advantages of operating with single mode laser devices and matched filtering at the receiver in the context of applications with significant solar background. The system performance for two types of direct-detection receivers, a PIN detector and less conventional silicon Photomultiplier technology will be presented

Come rilevare la visione professionale degli insegnanti. Uno schema di codifica

L’uso dei video a supporto dello sviluppo delle competenze di insegnamento rappresenta una opportunità ampiamente indagata nella ricerca educativa. In questo ambito, presso l’Università di Cagliari, in collaborazione con l’Università di California-Irvine, si è avviato un progetto di formazione degli insegnanti basato sull’uso delle tecnologie digitali per la video-osservazione con l’obiettivo di favorire lo sviluppo delle competenze di visione professionale (professional vision), intesa come la competenza di notare e attribuire significato a ciò che di rilevante avviene in classe in relazione all’apprendimento degli studenti. In linea con gli obiettivi del progetto, sulla base di modelli già affermati nella letteratura internazionale, riferibili prevalentemente all’area della didattica della matematica, gli autori hanno sviluppato un primo schema di codifica a otto dimensioni delle competenze di visione professionale, caratterizzato dalla trasversalità rispetto agli specifici ambiti disciplinari. Nel presente contributo, si introducono i fondamenti di tale costrutto, si presentano le dimensioni e indicatori dello schema, e se ne discutono ambiti di applicazione, potenzialità e criticità.The use of video to support the development of teaching competencies represents an opportunity that is widely investigated in educational research. In this area, at the University of Cagliari, in collaboration with the University of California-Irvine, a teacher professional development project based on the use of video technology and focused on video observations was initiated. The project’s objective is to support the development of professional vision competencies, that is the ability to notice and make sense of fundamental classroom events that are relevant to student learning. In alignment with the project objectives and drawing from existing frameworks from the international literature, particularly from the field of mathematics education, the authors have developed an initial coding system of eight dimensions that captures teacher professional vision across various disciplinary fields. In the present contribution, the construct of professional vision is introduced, the dimensions and indicators of the coding framework are presented, and applications, potentialities, and critical aspects are discussed

Skeletal stigmata as keys to access to the composite and ancient Gorlin-Goltz syndrome history: The Egypt, Pompeii and Herculaneum lessons

There are several genetic diseases with a wide spectrum of congenital bone stigmata in association to cutaneous and visceral benign and malignant neoplasms. Gorlin-Goltz syndrome, also named nevoid basal cell carcinoma syndrome, is an autosomal dominant systemic disease with almost complete penetrance and high intra-familial phenotypic variability, caused by germline mutations of the gene PTCH1. The syndrome is characterized by unusual skeletal changes and high predisposition to the development of multiple basal cell carcinomas, odontogenic keratocysts tumors and other visceral tumors. The Gorlin syndrome, clinically defined as distinct syndrome in 1963, existed during Dynastic Egyptian times, as revealed by a costellation of skeletal findings compatible with the syndrome in mummies dating back to 3000years ago and, most likely, in the ancient population of Pompeii. These paleogenetic and historical evidences, together with the clinical and biomolecular modern evidences, confirm the quite benign behavior of the syndrome and the critical value of the multiple and synchronous skeletal anomalies in the recognition of these rare and complex genetic disease

Underwater optical communication systems

I present in this thesis the results of my research in the field of underwater optical communication system (UOCS). Recently, underwater free-space optical (FSO) communication has been one of the major interesting research subjects due to the high demand for underwater activities that require high-bandwidth and flexible solutions. An optical communication system consists of three main blocks: transmitter, medium and receiver. Therefore, I provide an introduction to the topic, outlining the physical reasons and the engineering challenges that are behind the following sections. Among others, the optical properties of ocean water, the optimum wavelength selection and a description of the main system components are provided so that the system link budget can be subsequently optimised. Various modulation schemes adopted in free-space optics communication are evaluated and compared with a focus on the most power-efficient modulation format that offers successful and reliable data transmission. The system performances are numerically investigated using statistical analysis techniques over a typical range of achievable SNR in an underwater scenario. The characterisation and the data performance of a commercial GaN-based laser diode operating at 450 nm are presented. The detrimental impact of the solar background power on the system performance and the strategy to minimise its contribution is also discussed for a conventional Silicon PIN detector and the novel Silicon PhotoMultiplier (SiPM) technology. The design trade-off between the performance improvement given by an optical narrow bandpass filter matching a Fraunhofer line and the field-of-view of the receiver is also presented. A flexible MATLAB model has been developed to simulate a range of different scenarios and evaluate the system performances in different situations and the necessary design trade-off. A novel free-space waveguiding method is also presented for laser-based underwater communication systems. The proposed Underwater Wireless Acousto-Optic Waveguide (UWAOW) generates a localised modification of the refractive index of seawater in response to an acoustic field. Two geometries and their modelling are provided in order to take advantage of the proposed technique. These results show the importance of this emerging, challenging and fascinating contemporary research field

Universal scaling of a classical impurity in the quantum Ising chain

We study finite size scaling for the magnetic observables of an impurity residing at the endpoint of an open quantum Ising chain in a transverse magnetic field, realized by locally rescaling the magnetic field by a factor $\mu \neq 1$. In the homogeneous chain limit at $\mu = 1$, we find the expected finite size scaling for the longitudinal impurity magnetization, with no specific scaling for the transverse magnetization. At variance, in the classical impurity limit, $\mu = 0$, we recover finite scaling for the longitudinal magnetization, while the transverse one basically does not scale. For this case, we provide both analytic approximate expressions for the magnetization and the susceptibility as well as numerical evidences for the scaling behavior. At intermediate values of $\mu$, finite size scaling is violated, and we provide a possible explanation of this result in terms of the appearance of a second, impurity related length scale. Finally, on going along the standard quantum-to-classical mapping between statistical models, we derive the classical counterpart of the quantum Ising chain with an impurity at its endpoint as a classical Ising model on a square lattice wrapped on a half-infinite cylinder, with the links along the first circle modified as a function of $\mu$.Comment: Update closer to published versio