MICROSCALE DIELECTRIC ANTI-REFLECTION COATINGS FOR PHOTOVOLTAICS

In order to power our planet for the next century, clean energy technologies need to be developed and deployed. Photovoltaic solar cells, which convert sunlight into electricity, are a clear option; however, they currently supply 0.1% of the US electricity due to the relatively high cost per Watt of generation. Thus, our goal is to create more power from a photovoltaic device, while simultaneously reducing its price. To accomplish this goal, we are creating new high efficiency anti-reflection coatings that allow more of the incident sunlight to be converted to electricity, using simple and inexpensive coating techniques that enable reduced manufacturing costs. Traditional anti-reflection coatings (consisting of thin layers of non-absorbing materials) rely on the destructive interference of the reflected light, causing more light to enter the device and subsequently get absorbed. While these coatings are used on nearly all commercial cells, they are wavelength dependent and are deposited using expensive processes that require elevated temperatures, which increase production cost and can be detrimental to some temperature sensitive solar cell materials. We are developing two new classes of anti-reflection coatings (ARCs) based on textured dielectric materials: (i) a transparent, flexible paper technology that relies on optical scattering and reduced refractive index contrast between the air and semiconductor and (ii) silicon dioxide (SiO2) nanosphere arrays that rely on collective optical resonances. Both techniques improve solar cell absorption and ultimately yield high efficiency, low cost devices. For the transparent paper-based ARCs, we have recently shown that they improve solar cell efficiencies for all angles of incident illumination reducing the need for costly tracking of the sun’s position. For a GaAs solar cell, we achieved a 24% improvement in the power conversion efficiency using this simple coating. Because the transparent paper is made from an earth abundant material (wood pulp) using an easy, inexpensive and scalable process, this type of ARC is an excellent candidate for future solar technologies. The coatings based on arrays of dielectric nanospheres also show excellent potential for inexpensive, high efficiency solar cells. The fabrication process is based on a Meyer rod rolling technique, which can be performed at room-temperature and applied to mass production, yielding a scalable and inexpensive manufacturing process. The deposited monolayer of SiO2 nanospheres, having a diameter of 500 nm on a bare Si wafer, leads to a significant increase in light absorption and a higher expected current density based on initial simulations, on the order of 15-20%. With application on a Si solar cell containing a traditional anti-reflection coating (Si3N4 thin-film), an additional increase in the spectral current density is observed, 5% beyond what a typical commercial device would achieve. Due to the coupling between the spheres originated from Whispering Gallery Modes (WGMs) inside each nanosphere, the incident light is strongly coupled into the high-index absorbing material, leading to increased light absorption. Furthermore, the SiO2 nanospheres scatter and diffract light in such a way that both the optical and electrical properties of the device have little dependence on incident angle, eliminating the need for solar tracking. Because the layer can be made with an easy, inexpensive, and scalable process, this anti-reflection coating is also an excellent candidate for replacing conventional technologies relying on complicated and expensive processes.

Orthogonal persistence in Java supported by aspect- oriented programming and reflection

The persistence concern implemented as an aspect has been studied since the appearance of the Aspect-Oriented paradigm. Frequently, persistence is given as an example that can be aspectized, but until today no real world solution has applied that paradigm. Such solution should be able to enhance the programmer productivity and make the application less prone to errors. To test the viability of that concept, in a previous study we developed a prototype that implements Orthogonal Persistence as an aspect. This first version of the prototype was already fully functional with all Java types including arrays. In this work the results of our new research to overcome some limitations that we have identified on the data type abstraction and transparency in the prototype are presented. One of our goals was to avoid the Java standard idiom for genericity, based on casts, type tests and subtyping. Moreover, we also find the need to introduce some dynamic data type abilities. We consider that the Reflection is the solution to those issues. To achieve that, we have extended our prototype with a new static weaver that preprocesses the application source code in order to introduce changes to the normal behavior of the Java compiler with a new generated reflective code.

Running on Rooftops: a novel and critical reflection on writing from an identity of expatriation with an examination of West-meets-East encounters and attitudes depicted in literature

This thesis is in two parts: a creative work of fiction and a critical reflection on writing from an identity of expatriation. The creative work, a novel entitled Running on Rooftops, revolves around a fictitious community of expatriates living and working in China. As a new college graduate, Anne Henry, the novel’s protagonist and narrator, decides to spend a year teaching English in China. Twelve years later, though still unsure of how to make sense of the chain of events and encounters that left her with an X-shaped scar on her knee, she nevertheless tells the story, revealing how “just a year” can be anything but. The critical reflection, entitled Writing on Rooftops, explores the nature of expatriation as it relates to identity and writing, specifically in how West-meets-East encounters and attitudes are depicted in literature. In it, I examine the challenges and benefits of writing from an identity and mindset of expatriation as illustrated in the works of Western writers who themselves experienced and wrote from viewpoints of expatriation, particularly those Western writers who wrote of expatriation in China and Southeast Asia. The primary question addressed is how expatriation influences perception and how those perceptions among Western foreigners in China and Southeast Asia have been and can be reflected in literature. In the end, I argue that expatriation can be a valuable viewpoint to write from, offering new ways of seeing and describing our world, ourselves and the connections between the two.

Turismo espiritual en Sierra de la Ventana, Argentina. El caso de Calquín

En el marco de la presente investigación y a partir del análisis bibliográfico es posible detectar que nos encontramos inmersos en un contexto signado por profundos cambios en los diversos planos existenciales que generan incertidumbre y la necesidad de encontrar paz interior. De allí que, en determinadas circunstancias las personas inician un viaje para satisfacer sus necesidades espirituales. De esta manera se analiza el turismo espiritual-de reflexión, una modalidad de escasa difusión en nuestro país, basado en el desarrollo interior de la persona a través de diversas prácticas con el fin de vivenciar una experiencia trascendental. En este contexto, en los últimos tiempos, han surgido asociaciones y fundaciones que entre sus objetivos atienden los requerimientos interiores de los individuos, tal es el caso de la Asociación Civil Calquín ubicada a cuatro kilómetros de la localidad de Sierra de la Ventana (Argentina), sobre la cual se focaliza el presente trabajo. [en] As part of this research and from the literature review is possible to detect that we are immersed in a context marked by profound changes in the various planes of existence that generate uncertainty and the need to find inner peace. Hence, in certain circumstances people start a journey to meet their spiritual needs. In this way is analyzed spiritual-reflection tourism, a type of tourism with limited distribution in our country, based on the inner development of the individual through various practices in order to feel a transcendental experience. In this context, in recent times, there have been associations and foundations among its objectives serve the inner needs of individuals, as in the case of Calquín Civil Association located four kilometers from the town of Sierra de la Ventana (Argentina) on which this paper focuses.

Acousto-optic modulation of optical reflection properties in fiber Bragg gratings and the application in fiber lasers

This thesis aims to investigate the interaction of acoustic waves and fiber Bragg gratings (FBGs) in standard and suspended-core fibers (SCFs), to evaluate the influence of the fiber, grating and modulator design on the increase of the modulation efficiency, bandwidth and frequency. Initially, the frequency response and the resonant acoustic modes of a low frequency acousto-optic modulator (f < 1.2 MHz) are numerically investigated by using the finite element method. Later, the interaction of longitudinal acoustic waves and FBGs in SCFs is also numerically investigated. The fiber geometric parameters are varied and the strain and grating properties are simulated by means of the finite element method and the transfer matrix method. The study indicates that the air holes composing the SCF cause a significant reduction of the amount of silica in the fiber cross section increasing acousto-optic interaction in the core. Experimental modulation of the reflectivity of FBGs inscribed in two distinct SCFs indicates evidences of this increased interaction. Besides, a method to acoustically induce a dynamic phase-shift in a chirped FBG employing an optimized design of modulator is shown. Afterwards, a combination of this modulator and a FBG inscribed in a three air holes SCF is applied to mode-lock an ytterbium doped fiber laser. To improve the modulator design for future applications, two other distinct devices are investigated to increase the acousto-optic interaction, bandwidth and frequency (f > 10 MHz). A high reflectivity modulation has been achieved for a modulator based on a tapered fiber. Moreover, an increased modulated bandwidth (320 pm) has been obtained for a modulator based on interaction of a radial long period grating (RLPG) and a FBG inscribed in a standard fiber. In summary, the results show a considerable reduction of the grating/fiber length and the modulator size, indicating possibilities for compact and faster acousto-optic fiber devices. Additionally, the increased interaction efficiency, modulated bandwidth and frequency can be useful to shorten the pulse width of future all-fiber mode-locked fiber lasers, as well, to other photonic devices which require the control of the light in optical fibers by electrically tunable acoustic waves.

Ultrasonic wave reflection measurements on self-compacting pastes and concretes

The objective of this study was to extend the use of combined longitudinal (P-wave) and shear (S-wave) ultrasonic wave reflection (UWR) to monitor the setting and stiffening of self-compacting pastes and concretes. An additional objective was to interpret the UWR responses of various modified cement pastes. A polymeric buffer with acoustic impedance close to that of cement paste, high impact polystyrene, was chosen to obtain sensitive results from the early hydration period. Criteria for initial and final set developed by our group in a prior study were used to compute setting times by UWR. UWR results were compared with standard penetration measurements. Stiffening behavior and setting times for normal cement pastes, pastes modified with mineral and chemical admixtures, self-compacting pastes, and concretes were explored using penetration resistance, S-wave and P-wave reflection. All three methods showed that set times of pastes varied linearly with w/c, that superplasticizer and fly ash delayed the set times of pastes, and that differences in w/cm, sp/cm, and fa/cm could be detected. Final set times determined from UWR correlated well with those from penetration resistance. Initial set times from S-wave reflection did not correlate very well with those from penetration resistance. Final set times from P-wave and S-wave reflection were roughly the same. Pastes with different chemical admixtures were tested, and the effects of these admixtures on stiffening were determined using UWR. Self-compacting concretes were studied using UWR, and their response and setting times were largely similar to that of corresponding self-compacting pastes. The P-wave reflection response was explored in detail, and the phenomenon of partial debonding and the factors affecting it were explained. Partial debonding is probably caused by autogenous shrinkage at final set, and was controlled and limited by water. The extent of partial debonding was higher with the transducers placed on the side as opposed to the bottom, and the S-wave transducer seemed to promote debonding in the P-wave reflection, whereas the P-wave transducer seemed to reduce debonding in the S-wave reflection. Simultaneous formwork pressure testing and UWR were performed; however, no clear correlation was seen between the two properties.

10 th semester pre-service teacher beliefs and cognitive dissonances : a narrative reflection on efl practice at la Salle University

Tesis (Licenciado en Lenguas Castellana, Inglés y Francés).--Universidad de La Salle. Facultad de Ciencias de La Educación. Licenciatura en Lengua Castellana, Inglés y Francés, 2014

The interaction factor as a challenge for foreign language learning in the technology based education: a pedagogical reflection

The author carries out a pedagogical reflection on how the technology driven distance learning repeatedly neglects the scientific achievements of Second Language Acquisition and Language Pedagogy. Seeing communicative competence as a major goal of a language classroom, she presents the main challenges that the communicative approach poses to distance learning. To this end, a general distance learning theory by Moore is adapted to the needs of language education, through a distinction between three aspects of learner interaction – with the teacher, with other learners and with content. In this three-dimensional paradigm the learner is seen as the main actor of the process, the teacher as a facilitator, the text as a main source of communicative data and the learner autonomy as the fundament of the process.

Loop openness: a video reflection on the open work of art

The objective of this article is to reflect on the video art work in its loop production to perceive the possibility of it being received as an open work. In order to contextualize this reflection the text is anchored in the concept of image-crystal from Gilles Deleuze. For the purpose of empirically explore theoretical concepts such as video art, open work and image-crystal it was produced a practical project of video art that intends to reflect on the notion of time in a context of a loop exhibition. Therefore this project aims to motivate the reflection on the loop as a mechanism to contour the ephemeral character of video art and, at the same time, it seeks to emphasize questions about the element of multiplicity and plurality in art. It is a scientific and artistic project in which the practical component supports the dialectic between theory and practice, action and reflection. In this sense, based on the video entitled "The Walk" this article demonstrates how the theoretical concepts were used to support the artistic creation. Finally the conclusions sustain that the work of video art, when presented in loop, is a creative and expository strategy which encourages multiple interpretations that vary according to the narrative, the context in which it takes place and the attitude and the background of the spectator.

Systems 1 and 2 thinking processes and cognitive reflection testing in medical students

Background: Diagnostic decision-making is made through a combination of Systems 1 (intuition or pattern-recognition) and Systems 2 (analytic) thinking. The purpose of this study was to use the Cognitive Reflection Test (CRT) to evaluate and compare the level of Systems 1 and 2 thinking among medical students in pre-clinical and clinical programs. Methods: The CRT is a three-question test designed to measure the ability of respondents to activate metacognitive processes and switch to System 2 (analytic) thinking where System 1 (intuitive) thinking would lead them astray. Each CRT question has a correct analytical (System 2) answer and an incorrect intuitive (System 1) answer. A group of medical students in Years 2 & 3 (pre-clinical) and Years 4 (in clinical practice) of a 5-year medical degree were studied. Results: Ten percent (13/128) of students had the intuitive answers to the three questions (suggesting they generally relied on System 1 thinking) while almost half (44%) answered all three correctly (indicating full analytical, System 2 thinking). Only 3-13% had incorrect answers (i.e. that were neither the analytical nor the intuitive responses). Non-native English speaking students (n = 11) had a lower mean number of correct answers compared to native English speakers (n = 117: 1.0 s 2.12 respectfully: p < 0.01). As students progressed through questions 1 to 3, the percentage of correct System 2 answers increased and the percentage of intuitive answers decreased in both the pre-clinical and clinical students. Conclusions: Up to half of the medical students demonstrated full or partial reliance on System 1 (intuitive) thinking in response to these analytical questions. While their CRT performance has no claims to make as to their future expertise as clinicians, the test may be used in helping students to understand the importance of awareness and regulation of their thinking processes in clinical practice.

Reflection Framework

Suggested framework for reflection

Reflection Framework - feedback

Expanding the framework for reflection

Reflection examples

Expanding the framework for reflection

Monomanias - auto-narrativas e auto-ficções: estudo sobre as manias do eu como sintoma civilizacional e seu reflexo nas artes plásticas : Monomanias - auto narratives and auto-fictions: study on the manias of the self as a civilizational symptom and their reflection in contemporay art

A palavra monomania provém do grego monos que se traduz por "um" e mania que significa "mania". O emprego do termo em psiquiatria deve-se a Esquirol e mais tarde a Pierre Janet. Contudo, o uso da palavra não se circunscreve ao campo da psiquiatria, o conceito de monomania é também usado para definir as denominadas "manias do eu". Nos dias de hoje, a subjectividade, a particularidade de cada indivíduo apartou-se da noção de Homem como um todo objectivo. A massificação gerou a sociedade do narcisismo. A World Wide Web permitiu ao sujeito dar a conhecer ao mundo a sua individualidade. O sujeito é livre de se mostrar, de se fazer ouvir, de contar as suas histórias e principalmente a sua própria. À semelhança do nosso quotidiano, podemos encontrar na arte contemporânea propostas artísticas que se prendem com o conceito de monomania, como o exemplo das mitologias individuais, auto-narrativas e auto-ficções de Sophie Calle: "de vivre sa vie pour faire ceuvre et de faire ceuvre pour vivre sa vie." ABSTRACT: Etymologically, "monomania" originates from the Greek words "monos" and "mania". The former refers to the notion of "one" and the latter to "mania". The term's introduction in the field of psychiatry is attributed first to Esquirol and later Pierre Janet. Usage of the word isn’t, however, exclusive to psychiatric jargon: the concept of monomania is also used to define so called "manias of the self’. Today, the subjectivity and specificity of each individual have distanced themselves from the notion of Man as an objective whole. Massification has led to a society of narcissism. The World Wide Web has allowed the subject to make her individuality known to the world at large. The subject is free to exhibit herself, make herself heard, tell her stories, and especially her own. ln a way similar to daily life, we find agendas in contemporary art that approach the concept of monomania, such as the personal mythologies, self-narratives and selffictions of Sophie Calle: "de vivre sa vie pour faire oeuvre et de faire oeuvre pour vivre sa vie."

“The most artistic lesson I ever heard” - a contribution to the reflection on the comment made by William James regarding a lesson by Ernst Mach

On November the 2nd 1882, William James visited Ernst Mach in Prague, and attended one of his lectures. The conversation with Mach and the lecture were marking events for James. Based, namely, on James’s lectures for teachers and on Mach’s lectures for the general public, we propose a reflection on the defining traits that made that event "the most artistic lesson [James] ever heard". We shall remark on the imaginative joy contained in these texts, which appear to embody some of James' key ideas on Education. The experience of knowledge about the world contained in the texts, reveals that "to experiment" means "not coldly to observe a thing happening outside us, but to undergo, to feel within oneself, to live oneself this or that manner of being".