Writing in a Mathematics Classroom: A Form of Communication and Reflection

In this action research study, I investigated the use of journaling in my seventh grade mathematics classroom. I discovered that journaling can be a very rewarding and beneficial experience for me and for my students. Through journaling, my students became more adept at using correct mathematical terminology in writing and in speaking. The students also believed that they learned the content more deeply and retained it better. Additionally, implementing mathematical journals caused me to emphasize the use of correct terminology and thorough explanations of mathematical thinking in classroom discussions. As a result of this research, I plan to refine my journaling process and continue to use mathematical journals with my future classes.

Experimental investigations on the first Townsend coefficient in pure isobutane

In this work we present results of the first Townsend coefficient (alpha) in pure isobutane by measuring the current growth as a function of the electric field strength in a pulsed irradiation regime. A Resistive Plate Chamber (RPC)-like configuration was used. To validate this method, as well as to crosscheck the experimental apparatus, measurements of the alpha parameter were firstly carried out with pure nitrogen and the results compared to the accurate data available in the literature. The data obtained with isobutane in a field range from 145 Td up to 200 Td were well-matched to those calculated with Magboltz versions 2.7.1 and 2.8.6. The experimental consistency of these results with other published data in the range of 550-1300 Td was very good, as demonstrated by the use of the Korff parameterization. (C) 2012 Elsevier B.V. All rights reserved.

Therapeutic Project at Extra-Hospital Mental Health Services: a critical reflection on the elaboration and management of services' therapeutic projects

Based on a study conducted in Ribeirao Preto, SP, Brazil in extra-hospital mental health services that addressed the organization of these services, therapeutic projects and the inclusion of psychosocial rehabilitation in health actions available, a theoretical-critical reflection concerning the development process of the therapeutic projects by the services' teams is presented. The qualitative study was conducted in an outpatient clinic and a Psychosocial Care Center. Data were collected through semi-structured interviews and focal groups. Data analysis was based on the hermeneutic dialectic philosophy of Jurgen Habermas according to the techniques of reconstruction and interpretation. Data analysis revealed that professionals have difficulty developing and managing therapeutic projects. Health actions are made available without being concretely supported by a proposal guiding the service's practical activities. The therapeutic projects are referred by professionals as the result of guidelines provided by management levels or technical orientations inherent to each profession but not as an activity that represents a philosophy of work of the health team. When the therapeutic project is focused on as a type of consensus that results from a communicative action directed to a mutual and intersubjective understanding among the members of the mental health extra-hospital team, the difficulties of the services' team dialogically organizing themselves to collectively construct the therapeutic project is evidenced.

Work and Inter-subjectivity: a theoretical reflection on its dialectics in the field of health and nursing

This theoretical reflection intends to show the inter-subjective relationship that takes place in health and nursing practices under the following theoretical perspectives: Institutional Analysis, Psychodynamics of Labor and the Theory of Communicative Action, with an emphasis on the latter. Linking these concepts to the Marxist approach to work in the field of health emerges from recognizing the need for its continuous reconstruction-in this case, with a view to understand the interaction and communication intrinsic to work in action. The theory of Communicative Action seeks to consider these two inextricable dimensions: work as productive action and as interaction. The first corresponds to instrumental action based on technical rules with a production-guided rationale. The second refers to the interaction that takes place as communicative action and seeks understanding among subjects. We assume that adopting this theoretical perspective in the analysis of health and nursing practices opens new possibilities for clarifying its social and historical process and inter-subjective connections.

Influence of fast and slow distillation on ethyl carbamate content and on coefficient of non-alcohol components in Brazilian sugarcane spirits

Ethyl carbamate is an impurity present in distilled beverages. Given the risk of it being a carcinogenic substance, Brazilian legislation has determined that its presence in distilled beverages, such as 'aguardente' and 'cachaca' (two types of sugarcane spirits), should be limited to a maximum of 150 mu g/L. Ordinary spirits usually contain variable amounts of ethyl carbamate, although in lower concentrations than the maximum determined by law. The finding that commercial spirits had a much lower concentration of this impurity (around 50 mu g/L) led the authors to research the reasons for the differences, and these are explored in this paper, with a focus on the speed of the distillation process and its influence on the spirit's composition. The team conducted research in a sugarcane distillery producing 'aguardente' using a simple pot still and measured the influence of fast and slow distillation on the presence of ethyl carbamate and non-alcohol components in the process. The results demonstrated that the speed of distillation was proportionally related to the concentration of ethyl carbamate and secondary components in the beverage's composition. Copyright (c) 2012 The Institute of Brewing & Distilling

The zero temperature coefficient in junctionless nanowire transistors

This Letter presents an analysis of the zero temperature coefficient (ZTC) bias in junctionless nanowire transistors (JNTs). Unlike in previous works, which had shown that JNT did not present a ZTC point, this work shows that ZTC may occur in JNTs depending mainly on the series resistance of the devices and its dependence on the temperature. Experimental results of drain current, threshold voltage, and series resistance are presented for both long and short channel n and p-type devices. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4744965]

Ultra-low friction coefficient in alumina-silicon nitride pair lubricated with water

In a ball-on-disc wear test, an alumina ceramic body sliding against a silicon nitride ceramic body in water achieved an ultra-low friction coefficient (ULFC) of 0.004. The profilometer and EDX measurements indicated that the ULFC regime in this unmated Al2O3-Si3N4 pair was achieved because of the formation of a flat and smooth interface of nanometric roughness, which favored the hydrodynamic lubrication. The triboreactions formed silicon and aluminum hydroxides which contributed to decrease roughness and shear stress at the contact interface. This behavior enables the development of low energy loss water-based tribological systems using oxide ceramics. 13 2012 Elsevier B.V. All rights reserved.

Application of the Z-scan technique to determine the optical Kerr coefficient and two-photon absorption coefficient of magnetite nanoparticles colloidal suspension

We investigate the occurrence of the optical Kerr effect and two-photon absorption when an oil-based magnetic Fe3O4 nanoparticles colloidal suspension is illuminated with high intensity femtosecond laser pulses. The frequency of the pulses is controlled and the Z-scan technique is employed in our measurements of the nonlinear optical Kerr coefficient (n(2)) and two-photon absorption coefficient (beta). From these values it was possible to calculate the real and imaginary parts of the third-order susceptibility. We observed that increasing the pulse frequency, additional physical processes take place, increasing artificially the absolute values of n(2) and beta. The experimental conditions are discussed to assure the obtention of reliable values of these nonlinear optical parameters, which may be useful in all-optical switching and optical power limiting applications. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4723829]

Residual stresses in Y-TZP crowns due to changes in the thermal contraction coefficient of veneers

Objective. To test the hypothesis that the difference in the coefficient of thermal contraction of the veneering porcelain above (˛liquid) and below (˛solid) its Tg plays an important role in stress development during a fast cooling protocol of Y-TZP crowns. Methods. Three-dimensional finite element models of veneered Y-TZP crowns were developed. Heat transfer analyses were conducted with two cooling protocols: slow (group A) and fast (groups B–F). Calculated temperatures as a function of time were used to determine the thermal stresses. Porcelain ˛solid was kept constant while its ˛liquid was varied, creating different ˛/˛solid conditions: 0, 1, 1.5, 2 and 3 (groups B–F, respectively). Maximum ( 1) and minimum ( 3) residual principal stress distributions in the porcelain layer were compared. Results. For the slowly cooled crown, positive 1 were observed in the porcelain, orientated perpendicular to the core–veneer interface (“radial” orientation). Simultaneously, negative 3 were observed within the porcelain, mostly in a hoop orientation (“hoop–arch”). For rapidly cooled crowns, stress patterns varied depending on ˛/˛solid ratios. For groups B and C, the patterns were similar to those found in group A for 1 (“radial”) and 3 (“hoop–arch”). For groups D–F, stress distribution changed significantly, with 1 forming a “hoop-arch” pattern while 3 developed a “radial” pattern. Significance. Hoop tensile stresses generated in the veneering layer during fast cooling protocols due to porcelain high ˛/˛solid ratio will facilitate flaw propagation from the surface toward the core, which negatively affects the potential clinical longevity of a crown.

Trasmission and Reflection (ATR)Far-Infrared Spectroscopy Applied in the Analysis of Cultural Heritage Materials

FIR spectroscopy is an alternative way of collecting spectra of many inorganic pigments and corrosion products found on art objects, which is not normally observed in the MIR region. Most FIR spectra are traditionally collected in transmission mode but as a real novelty it is now also possible to record FIR spectra in ATR (Attenuated Total Reflectance) mode. In FIR transmission we employ polyethylene (PE) for preparation of pellets by embedding the sample in PE. Unfortunately, the preparation requires heating of the PE in order to produces at transparent pellet. This will affect compounds with low melting points, especially those with structurally incorporated water. Another option in FIR transmission is the use of thin films. We test the use of polyethylene thin film (PETF), both commercial and laboratory-made PETF. ATR collection of samples is possible in both the MIR and FIR region on solid, powdery or liquid samples. Changing from the MIR to the FIR region is easy as it simply requires the change of detector and beamsplitter (which can be performed within a few minutes). No preparation of the sample is necessary, which is a huge advantage over the PE transmission method. The most obvious difference, when comparing transmission with ATR, is the distortion of band shape (which appears asymmetrical in the lower wavenumber region) and intensity differences. However, the biggest difference can be the shift of strong absorbing bands moving to lower wavenumbers in ATR mode. The sometimes huge band shift necessitates the collection of standard library spectra in both FIR transmission and ATR modes, provided these two methods of collecting are to be employed for analyses of unknown samples. Standard samples of 150 pigment and corrosion compounds are thus collected in both FIR transmission and ATR mode in order to build up a digital library of spectra for comparison with unknown samples. XRD, XRF and Raman spectroscopy assists us in confirming the purity or impurity of our standard samples. 24 didactic test tables, with known pigment and binder painted on the surface of a limestone tablet, are used for testing the established library and different ways of collecting in ATR and transmission mode. In ATR, micro samples are scratched from the surface and examined in both the MIR and FIR region. Additionally, direct surface contact of the didactic tablets with the ATR crystal are tested together with water enhanced surface contact. In FIR transmission we compare the powder from our test tablet on the laboratory PETF and embedded in PE. We also compare the PE pellets collected using a 4x beam condenser, focusing the IR beam area from 8 mm to 2 mm. A few samples collected from a mural painting in a Nepalese temple, corrosion products collected from archaeological Chinese bronze objects and samples from a mural paintings in an Italian abbey, are examined by ATR or transmission spectroscopy.

Refined Gelfand models for some finite complex reflection groups

In 'Involutory reflection groups and their models' (F. Caselli, 2010), a uniform Gelfand model is constructed for all complex reflection groups G(r,p,n) satisfying GCD(p,n)=1,2 and for all their quotients modulo a scalar subgroup. The present work provides a refinement for this model. The final decomposition obtained is compatible with the Robinson-Schensted generalized correspondence.

The electron antineutrino angular correlation coefficient a in free neutron decay: Testing the standard model with the aSPECT-spectrometer

The beta-decay of free neutrons is a strongly over-determined process in the Standard Model (SM) of Particle Physics and is described by a multitude of observables. Some of those observables are sensitive to physics beyond the SM. For example, the correlation coefficients of the involved particles belong to them. The spectrometer aSPECT was designed to measure precisely the shape of the proton energy spectrum and to extract from it the electron anti-neutrino angular correlation coefficient "a". A first test period (2005/ 2006) showed the “proof-of-principles”. The limiting influence of uncontrollable background conditions in the spectrometer made it impossible to extract a reliable value for the coefficient "a" (publication: Baessler et al., 2008, Europhys. Journ. A, 38, p.17-26). A second measurement cycle (2007/ 2008) aimed to under-run the relative accuracy of previous experiments (Stratowa et al. (1978), Byrne et al. (2002)) da/a =5%. I performed the analysis of the data taken there which is the emphasis of this doctoral thesis. A central point are background studies. The systematic impact of background on a was reduced to da/a(syst.)=0.61 %. The statistical accuracy of the analyzed measurements is da/a(stat.)=1.4 %. Besides, saturation effects of the detector electronics were investigated which were initially observed. These turned out not to be correctable on a sufficient level. An applicable idea how to avoid the saturation effects will be discussed in the last chapter.

Numerical studies of colloidal systems

The interplay of hydrodynamic and electrostatic forces is of great importance for the understanding of colloidal dispersions. Theoretical descriptions are often based on the so called standard electrokinetic model. This Mean Field approach combines the Stokes equation for the hydrodynamic flow field, the Poisson equation for electrostatics and a continuity equation describing the evolution of the ion concentration fields. In the first part of this thesis a new lattice method is presented in order to efficiently solve the set of non-linear equations for a charge-stabilized colloidal dispersion in the presence of an external electric field. Within this framework, the research is mainly focused on the calculation of the electrophoretic mobility. Since this transport coefficient is independent of the electric field only for small driving, the algorithm is based upon a linearization of the governing equations. The zeroth order is the well known Poisson-Boltzmann theory and the first order is a coupled set of linear equations. Furthermore, this set of equations is divided into several subproblems. A specialized solver for each subproblem is developed, and various tests and applications are discussed for every particular method. Finally, all solvers are combined in an iterative procedure and applied to several interesting questions, for example, the effect of the screening mechanism on the electrophoretic mobility or the charge dependence of the field-induced dipole moment and ion clouds surrounding a weakly charged sphere. In the second part a quantitative data analysis method is developed for a new experimental approach, known as "Total Internal Reflection Fluorescence Cross-Correlation Spectroscopy" (TIR-FCCS). The TIR-FCCS setup is an optical method using fluorescent colloidal particles to analyze the flow field close to a solid-fluid interface. The interpretation of the experimental results requires a theoretical model, which is usually the solution of a convection-diffusion equation. Since an analytic solution is not available due to the form of the flow field and the boundary conditions, an alternative numerical approach is presented. It is based on stochastic methods, i. e. a combination of a Brownian Dynamics algorithm and Monte Carlo techniques. Finally, experimental measurements for a hydrophilic surface are analyzed using this new numerical approach.

Total internal reflection fluorescence cross-correlation spectroscopy: theory and application for studying boundary slip phenomenon

I present a new experimental method called Total Internal Reflection Fluorescence Cross-Correlation Spectroscopy (TIR-FCCS). It is a method that can probe hydrodynamic flows near solid surfaces, on length scales of tens of nanometres. Fluorescent tracers flowing with the liquid are excited by evanescent light, produced by epi-illumination through the periphery of a high NA oil-immersion objective. Due to the fast decay of the evanescent wave, fluorescence only occurs for tracers in the ~100 nm proximity of the surface, thus resulting in very high normal resolution. The time-resolved fluorescence intensity signals from two laterally shifted (in flow direction) observation volumes, created by two confocal pinholes are independently measured and recorded. The cross-correlation of these signals provides important information for the tracers’ motion and thus their flow velocity. Due to the high sensitivity of the method, fluorescent species with different size, down to single dye molecules can be used as tracers. The aim of my work was to build an experimental setup for TIR-FCCS and use it to experimentally measure the shear rate and slip length of water flowing on hydrophilic and hydrophobic surfaces. However, in order to extract these parameters from the measured correlation curves a quantitative data analysis is needed. This is not straightforward task due to the complexity of the problem, which makes the derivation of analytical expressions for the correlation functions needed to fit the experimental data, impossible. Therefore in order to process and interpret the experimental results I also describe a new numerical method of data analysis of the acquired auto- and cross-correlation curves – Brownian Dynamics techniques are used to produce simulated auto- and cross-correlation functions and to fit the corresponding experimental data. I show how to combine detailed and fairly realistic theoretical modelling of the phenomena with accurate measurements of the correlation functions, in order to establish a fully quantitative method to retrieve the flow properties from the experiments. An importance-sampling Monte Carlo procedure is employed in order to fit the experiments. This provides the optimum parameter values together with their statistical error bars. The approach is well suited for both modern desktop PC machines and massively parallel computers. The latter allows making the data analysis within short computing times. I applied this method to study flow of aqueous electrolyte solution near smooth hydrophilic and hydrophobic surfaces. Generally on hydrophilic surface slip is not expected, while on hydrophobic surface some slippage may exists. Our results show that on both hydrophilic and moderately hydrophobic (contact angle ~85°) surfaces the slip length is ~10-15nm or lower, and within the limitations of the experiments and the model, indistinguishable from zero.