Origin of Second Harmonic Generation from individual Silicon Nanowires

We investigate Second Harmonic Generation from individual silicon nanowires and study the influence of resonant optical modes on the far-field nonlinear emission. We find that the polarization of the Second Harmonic has a size-dependent behavior and explain this phenomenon by a combination of different surface and bulk nonlinear susceptibility contributions. We show that the Second Harmonic Generation has an entirely different origin, depending on whether the incident illumination is polarized parallel or perpendicularly to the nanowire axis. The results open perspectives for further geometry-based studies on the origin of Second Harmonic Generation in nanostructures of high-index centrosymmetric semiconductors.Comment: 7 Pages, 4 Figures + 3 Pages, 6 Figures in Appendi

Communicative competence of a child with cerebral palsy and mild intellectual disability

In the article, the communicative competence of a 12 year old girl with cerebral palsy and mild intellectual disability was characterised. These developmental disorders exert a significant impact on child’s skills in the field of speech expression and perception. Moreover, they lead to speech disorders: oligophasia and dysarthria. The case study method was used to conduct the research. In the first part of this article the authors described two issues: cerebral palsy and intellectual disability. They indicated the causes, as well as the most common symptoms of these developmental disorders. In the next part the authors provided an extensive description of various diagnostic tests. They enabled the researchers to explore, among others, speech expression and perception, as well as phonematic hearing. The results of these different tests were thoroughly analysed. Consequently, it has been proved that the level of child’s linguistic and communication skills corresponds to the results achieved by children with similar deficits and disorders

AN EMPIRICAL STUDY OF STRATEGIES FOR UNDERSTANDING QUANTITATIVE DECISION MODELS

Demos is a modeling environment designed to help a co-operating team design, analyze, critique and refine quantitative models for policy research. Earlier research found that readers of Demos models tended to become disoriented while exploring models online. In response we have designed and implemented a graphical interface to Demos named Demaps. Demaps displays diagrams of the model structure, both dependence networks and abstraction hierarchies, to provide graphic context and direct manipulation style of interaction. We describe a study of the use of Demaps to understand and compare multiple versions of models. The study employs verbal protocol analysis to evaluate the design of Demaps and to discover expert strategies for model understanding and criticism. Subjects were able to learn to use Demaps effectively in about an hour to review and compare policy models and perform sensitivity analyses. The study describes two strategies used in reading models and suggests the desirability of additional facilities for recording model critiques and accessing detailed background information on models. *We gratefully acknowledge the contributions of many people, including Jill Larkin, Jim Morris, Granger Morgan, Andrew Appel. and our subjects. This work was supported by the Information Technology Center and the National Science Foundation under grant IST-8316890

Healthy Out of School Time: Developing National Quality Standards for Healthy Eating and Physical Activity

Afternoon programs are an important venue for promoting healthy eating and physical activity in children and youth. This project, co-led by investigators at the Institute on Out-of-School Time (NIOST), UMass Boston, and YMCA of the USA, used quantitative and qualitative methods to assess and respond to the need for national standards for healthy eating and physical activity in afterschool programs. This presentation provides an overview of this translational research with emphasis on development and dissemination of the evidence-based national guidelines for health eating and physical activity in afterschool programs

Desuetudo w rozumieniu Sądu Najwyższego i Trybunału Konstytucyjnego

The article’s goal is to specify how the jurisdiction of Supreme Court and Constitutional Tribunal of the Republic of Poland see desuetudo. It is preceded by a brief theoretical introduction. The examples show that we can tell about the desuetudo much more than just that it is caused by not applying the law and non-compliance with the law. In particular, desuetudo turns out to be restricted and cannot be applied to whichever norm.Celem artykułu jest określenie w jaki sposób orzecznictwo Sądu Najwyższego i Trybunału Konstytucyjnego rozumie pojęcie desuetudo. Poprzedzone zostało to krótkim wprowadzeniem teoretycznym. Na przykładach zostaje pokazane, że o desuetudo można powiedzieć znacznie więcej niż tylko to, że powoduje je niestosowanie i nieprzestrzeganie prawa. W szczególności, desuetudo okazuje się ograniczane i nie może dotyczyć dowolnej normy

Linear and nonlinear optical properties of high refractive index dielectric nanostructures

La nano-optique est un vaste domaine permettant d'étudier et d'exalter l'interaction lumière-matière à l'échelle nanométrique. Ce domaine couvre notamment la plasmonique, mais depuis quelques années, un effort est porté sur les nanostructures diélectriques à fort indice de réfraction (typiquement des semiconducteurs comme le silicium). Des effets similaires aux nanoparticules plasmoniques peuvent être obtenus, tels un comportement d'antenne et l'exaltation de phénomènes non linéaires (génération d'harmoniques), avec l'avantage de faibles pertes. Dans cette thèse, une analyse des propriétés optiques linéaires et non linéaires de nanostructures individuelles. Une première partie est dédiée aux nanofils de silicium qui supportent de fortes résonances optiques dont le nombre et la gamme spectrale, du proche UV au proche IR, sont fonction de leur diamètre. Dans ces conditions, l'exaltation du champ proche optique et un rapport surface sur volume élevé favorisent l'apparition de processus non linéaires. Ainsi la génération de seconde harmonique (SHG) par rapport au silicium massif est augmentée de deux ordres de grandeur. En outre, différentes contributions à l'origine de la SHG peuvent être adressées individuellement en fonction de la polarisation du laser d'excitation et de la taille des nanofils. Les résultats expérimentaux sont confrontés à des simulations numériques (méthode dyadique de Green, GDM), qui permettent d'identifier les différentes contributions. Dans une seconde partie, la méthode dyadique de Green est couplée à des algorithme évolutionnistes (EO) pour la conception et l'optimisation de propriétés optiques choisies de nanostructures semiconductrices ou métalliques, par exemple diffusion résonnante de différentes longueurs d'ondes pour différentes polarisations.Des échantillons de nanostructures de silicium, réalisés à partir des résultats de l'EO, vérifient avec succès les prédictions de l'algorithme d'optimisation, démontrant l'énorme potentiel de l'EO pour de nombreuses applications en nanophotonique requérant une optimisation simultanée de différents paramètres.Nano-photonic structures offer a highly interesting platform to enhance light-matter interaction on a nanometer scale. Recently, high-index dielectric structures have gained increasing attention as possible low-loss alternatives to plasmonic nano-antennas made from noble metals. Furthermore, since non-linear effects offer many unique functionalities like the coherent up-conversion of photons, including the generation of harmonics, many efforts are being made to exploit such phenomena in nano-photonics. In this thesis, an analysis is presented on nonlinear optical effects in individual dielectric structures, specifically in silicon nanowires (SiNWs). Nanowires develop strong optical resonances in the visible and infrared spectral range. In this context, strong enhancement of the optical near-field together with a large surface to volume ratio support the appearance of nonlinear effects. We show that, compared to bulk Si, a two orders of magnitude increase in second harmonic generation (SHG) is feasible and furthermore unravel different polarization and size-dependent contributions at the origin of the SHG. Numerical simulations are carried out to reaffirm these experimental findings for which a numerical technique is presented to describe nonlinear effects on the basis of the Green Dyadic Method (GDM). In the last part of the thesis, the GDM is used together with evolutionary optimization (EO) algorithms to tailor and optimize optical properties of photonic nano-structures. We eventually fabricate samples, based on EO design, and successfully verify the predictions of the optimization algorithm. It turns out that EO is an extremely versatile tool and has a tremendous potential for many kinds of further applications in nano-optics