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.

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."

Structural development of silicated films self-assembled at the air-water interface

The development of structure perpendicular to and in the plane of the interface has been studied for mesoporous silicate films self-assembled at the air/water interface. The use of constrained X-ray and neutron specular reflectometry has enabled a detailed study of the structural development perpendicular to the interface during the pre-growth phase. Off-specular neutron reflectometry and grazing incidence X-ray diffraction has enabled the in-plane structure to be probed with excellent time resolution. The growth mechanism under the surfactant to silicate source ratios used in this work is clearly due to the self-assembly of micellar and molecular species at the air/liquid interface, resulting in the formation of a planar mesoporous film that is tens of microns thick. (C) 2003 Elsevier Science B.V. All rights reserved.

Democratic dialogue and collective learning in the context of self-managed teams

This paper provides a longitudinal, empirical view of the multifaceted and reciprocal processes of organizational learning in a context of self-managed teams. Organizational learning is seen as a social construction between people and actions in a work setting. The notion of learning as situated (Brown & Duguid 1989, Lave& Wenger 1991, Gherardi & al. 1998, Easterby-Smith & Araujo 1999, Abma 2003) opens up the possibility for placing the focus of research on learning in the community rather than in individual learning processes. Further, in studying processes in their social context, we cannot avoid taking power relations into consideration (Contu & Willmott 2003). The study is based on an action research with a methodology close to the ‘democratic dialogue’ presented by Gustavsen (2001). This gives a ground for research into how the learning discourse developed in the case study organization over a period of 5 years, during which time the company abandoned a middle management level of hierarchy and the teams had to figure out how to work as self-managed units. This paper discusses the (re)construction of power relations and its role in organizational learning. Power relations are discussed both in vertical and horizontal work relations. A special emphasis is placed on the dialectic between managerial aims and the space for reflection on the side of employees. I argue that learning is crucial in the search for the limits for empowerment and that these limits are negotiated both in actions and speech. This study unfolds a purpose-oriented learning process, constructing an open dialogue, and describes a favourable context for creative, knowledge building communities.

The gain-loss asymmetry and single-self preferences

Kahneman and Tversky asserted a fundamental asymmetry between gains and losses, namely a reflection effect which occurs when an individual prefers a sure gain of $ pz to anuncertain gain of $ z with probability p, while preferring an uncertain loss of $z with probability p to a certain loss of $ pz.We focus on this class of choices (actuarially fair), and explore the extent to which thereflection effect, understood as occurring at a range of wealth levels, is compatible with single-self preferences.We decompose the reflection effect into two components, a probability switch effect,which is compatible with single-self preferences, and a translation effect, which is not. To argue the first point, we analyze two classes of single-self, nonexpected utility preferences, which we label homothetic and weakly homothetic. In both cases, we characterize the switch effect as well as the dependence of risk attitudes on wealth.We also discuss two types of utility functions of a form reminiscent of expected utility but with distorted probabilities. Type I always distorts the probability of the worst outcome downwards, yielding attraction to small risks for all probabilities. Type II distorts low probabilities upwards, and high probabilities downwards, implying risk aversion when the probability of the worst outcome is low. By combining homothetic or weak homothetic preferences with Type I or Type II distortion functions, we present four explicit examples: All four display a switch effect and, hence, a form of reflection effect consistent a single self preferences.

Self-similarity of complex networks and hidden metric spaces

We demonstrate that the self-similarity of some scale-free networks with respect to a simple degree-thresholding renormalization scheme finds a natural interpretation in the assumption that network nodes exist in hidden metric spaces. Clustering, i.e., cycles of length three, plays a crucial role in this framework as a topological reflection of the triangle inequality in the hidden geometry. We prove that a class of hidden variable models with underlying metric spaces are able to accurately reproduce the self-similarity properties that we measured in the real networks. Our findings indicate that hidden geometries underlying these real networks are a plausible explanation for their observed topologies and, in particular, for their self-similarity with respect to the degree-based renormalization.

Quette place pour l'automesure glycémique dans la prise en charge du diabète de type 2 [Which role for self-monitoring of blood glucose in type 2 diabetes?]

There is a sustained controversy in the literature about the role and utility of self-monitoring of blood glucose (SMBG) in type 2 diabetes. The study results in this field do not provide really useful clues for the integration of SMBG in the follow-up of the individual patient, because they are based on a misconception of SMBG. It is studied as if it was a medical treatment whose effect on glycemic control is to be isolated. However, SMBG has no such intrinsic effect. It gains its purpose only as an inseparable component of a comprehensive and structured educational strategy. To be appropriate this strategy cannot be based on the health care professionals' view on diabetes only. It rather has to be tailored to the individual patient's needs through an ongoing process of shared reflection with him.

Coherent patterns and self-induced diffraction of electrons on a thin nonlinear layer

Electron scattering on a thin layer where the potential depends self-consistently on the wave function has been studied. When the amplitude of the incident wave exceeds a certain threshold, a soliton-shaped brightening (darkening) appears on the layer causing diffraction of the wave. Thus the spontaneously formed transverse pattern can be viewed as a self-induced nonlinear quantum screen. Attractive or repulsive nonlinearities result in different phase shifts of the wave function on the screen, which give rise to quite different diffraction patterns. Among others, the nonlinearity can cause self-focusing of the incident wave into a beam, splitting in two "beams," single or double traces with suppressed reflection or transmission, etc.

Valuing and encouraging critical reflection in pre-service teacher education

This qualitative study was designed to investigate aspects related to valuing and encouraging critical reflection in pre-service teacher education. An examination of the place and function of practicum logbooks as used at Covenant Canadian Reformed Teachers' College, a small private college which offers pre-service teacher education formed the core of the research. An analysis of the practicum logbooks written by five student teachers during three different practicum placements was performed at two levels. First, a content analysis served to identify general and specific categories within the practice teaching contextas a learning experience. Secondly, in-depth intuitive and thematic analyses of the entries which related specifically to reflection as a learning experience gave rise to critical questions. Throughout the process, the five participants formed an active and involved group of co-researchers, adding their voices to the narrative of the learning experience. Variables such as personality type, learning style and self-directedness added a dimension which deepened and emiched the study. The result of the study suggests that practicum logbooks form a valuable base for valuing and encouraging critical reflection in pre-service teacher education. The results also suggest that not all students appear to be equally capable of critical reflection. Recognizing that teacher education exists as a continuum appears to support the findings that in their journey along this continuum, student teachers not only move from reflection-on-action to reflection-in-action, but also from content to process to premise reflection. An awareness of contributing factors such as personality type, degree of risk-taking, preferred learning style and self-directedness on the part of teacher-educators will serve to create a climate of trust in which student teachers can safely develop critical reflection, using practicum logbooks as one possible medium.

Letting go : a self-study utilizing critical literacy as method in improving my practice /

This is a Self-study about my role as a teacher, driven by the question: "How do I improve my practice?" (Whitehead, 1989)? In this study, I explored the discomfort that I had with the way that I had been teaching. Specifically, I worked to uncover the reasons behind my obsessive (mis)management of my students. I wrote of how I came to give my Self permission for this critique: how I came to know that all knowledge is a construction, and that my practice, too, is a construction. I grounded this journey within my experiences. I constructed these experiences in narrative fomi in order to reach a greater understanding of how I came to be the teacher I initially was. I explored metaphors that impacted my practice, re-constructed them, and saw more clearly the assumptions and influences that have guided my teaching. I centred my inquiry into my teaching within an Action Reflection methodology, bon-owing Jack Whitehead's (1989) term to describe my version of Action Research. I relied upon the embedded cyclical pattern of Action Reflection to understand my teaching Self: beginning from a critical moment, reflecting upon it, and then taking appropriate action, and continuing in this way, working to improve my practice. To understand these critical moments, I developed a personal definition of critical literacy. I then tumed this definition inward. In treating my practice as a textual production, I applied critical literacy as a framework in coming to know and understand the construction that is my teaching. I grounded my thesis journey within my Self, positioning my study within my experiences of being a grade 1 teacher struggling to teach critical literacy. I then repositioned my journey to that of a grade 1 teacher struggling to use critical literacy to improve my practice. This journey, then, is about the transition from critical literacyit as-subject to critical literacy-as-instmctional-method in improving my practice. I joumeyed inwards, using a critical moment to build new understandings, leading me to the next critical moment, and continued in this cyclical way. I worked in this meandering yet deliberate way to reach a new place in my teaching: one that is more inclusive of all the voices in my room. I concluded my journey with a beginning: a beginning of re-visioning my practice. In telling the stories of my journey, of my teaching, of my experiences, I changed into the teacher that I am more comfortable with. I've come to the frightening conclusion that I am the decisive element in the classroom. It's my personal approach that creates the climate. It's my daily mood that makes the weather As a teacher, I possess a tremendous power to make a person's life miserable or joyous. I can be a tool of torture or an instrument of inspiration. I can humiliate or humour, hurt or heal. In all situations, it is my response that decides whether a crisis will be escalated or de-escalated and a person humanized or de-humanized. (Ginott, as cited in Buscaglia, 2002, p. 22)

What is reflection? A conceptual analysis of major definitions and a proposal of a five-component definition and model

La réflexion est considérée comme un élément significatif de la pédagogie et de la pratique médicales sans qu’il n’existe de consensus sur sa définition ou sur sa modélisation. Comme la réflexion prend concurremment plusieurs sens, elle est difficile à opérationnaliser. Une définition et un modèle standard sont requis afin d’améliorer le développement d’applications pratiques de la réflexion. Dans ce mémoire, nous identifions, explorons et analysons thématiquement les conceptualisations les plus influentes de la réflexion, et développons de nouveaux modèle et définition. La réflexion est définie comme le processus de s’engager (le « soi » (S)) dans des interactions attentives, critiques, exploratoires et itératives (ACEI) avec ses pensées et ses actions (PA), leurs cadres conceptuels sous-jacents (CC), en visant à les changer et en examinant le changement lui-même (VC). Notre modèle conceptuel comprend les cinq composantes internes de la réflexion et les éléments extrinsèques qui l’influencent.

Coherent patterns and self-induced diffraction of electrons on a thin nonlinear layer

Electron scattering on a thin layer where the potential depends self-consistently on the wave function has been studied. When the amplitude of the incident wave exceeds a certain threshold, a soliton-shaped brightening (darkening) appears on the layer causing diffraction of the wave. Thus the spontaneously formed transverse pattern can be viewed as a self-induced nonlinear quantum screen. Attractive or repulsive nonlinearities result in different phase shifts of the wave function on the screen, which give rise to quite different diffraction patterns. Among others, the nonlinearity can cause self-focusing of the incident wave into a beam, splitting in two "beams," single or double traces with suppressed reflection or transmission, etc.

Influence of the solvent on the self-assembly of a modified amyloid beta peptide fragment. I. Morphological investigation

The solvent-induced transition between self-assembled structures formed by the peptide AAKLVFF is studied via electron microscopy, light scattering, and spectroscopic techniques. The peptide is based on a core fragment of the amyloid beta-peptide, KLVFF, extended by two alanine residues. AAKLVFF exhibits distinct structures of twisted fibrils in water or nanotubes in methanol. For intermediate water/methanol compositions, these structures are disrupted and replaced by wide filamentous tapes that appear to be lateral aggregates of thin protofilaments. The orientation of the beta-strands in the twisted tapes or nanotubes can be deduced from X-ray diffraction on aligned stalks, as well as FT-IR experiments in transmission compared to attenuated total reflection. Strands are aligned perpendicular to the axis of the twisted fibrils or the nanotubes. The results are interpreted in light of recent results on the effect of competitive hydrogen bonding upon self-assembly in soft materials in water/methanol mixtures.

Waveguide features in self-patternable amine functionalized organic-inorganic hybrids

We report the use of organic-inorganic sol-gel derived poly(oxyehylene)/ siloxane hybrid doped with methacrylic acid modified zirconium (IV) n-propoxide for the fabrication of low cost waveguides trough direct UV laser writing. The organic-inorganic hybrids were processed as monoliths with size and shape control. The effective guiding region was identified and the number of modes was estimated via mode field analyses. A grating was successfully superimposed on the channel and the respective reflection spectrum was measured, enabling the determination of the guiding region dimension, the calculation of the effective refractive index of the guided mode. © 2007 IEEE.