Envisioning my mathematics classroom: Validating the Draw-a-Mathematics-Teacher-Test Rubric

Teachers need the opportunity to reflect, rethink, and adapt as they continually develop their image of their role in their mathematics classrooms. Thus, the purpose of this research was to examine how the Draw-a-Mathematics-Teacher-Test (DAMTT) and rubric can be used to assess preservice elementary teachers’ images of and beliefs about their future mathematics classrooms and validate the Draw-a-Math-TeacherTest-Rubric (DAMTT-R). Results suggest that the DAMTT-R is a valid measure and yields consistent results. Additionally, analysis of preservice elementary teachers’ (PETs) DAMTT revealed that only slightly more than one-third (36.9%) drew a picture and described their classroom in such a way that it reflected beliefs aligned with student-centered pedagogic practices. While mathematics educators may aim for the majority of PETs to leave their programs having developed beliefs aligned with and supportive of student-centered pedagogic practices, the results of this study revealed that 25% of PETs held beliefs that align with teacher-centered pedagogic practices. Lastly, 38.1% of the PETs reflected beliefs about their pedagogic practices, as measured by the DAMTT and the DAMTT-R, aligned with a transition between teacher-centered and student-centered.     

An inconsistence-free integral-based dynamic one- and two-parameter mixed model

The development of the dynamic procedure as well as the deeper understanding of the link between filtering, modelling and numerics, allowed Large Eddy Simulation (LES) to make great progresses during the last years. Among several modelling approaches, the scale-similar-based modelling is based on the observation that the smallest resolved scales are the most active in the interaction with the unresolved ones. Owing to the low dissipation introduced by the scale-similar models (SSMs), the coupling with the eddy-viscosity model is often used in the so-called mixed models. Dynamic version of mixed models is historically based on the application of the test-filtering on the differential form of the filtered momentum equation. Such an approach is used for both the one and the two-coefficients mixed models. The use of the differential form of the filtered equations produces the well-known mathematical inconsistence caused by the need to extract arbitrarily the model functions out of filtering. It is known that, along with the eddy viscosity assumption, the magnitude of the Germano identity error (GIE) is strongly influenced. The mathematical inconsistence in the extraction of the dynamic eddy viscosity coefficient was recently superseded by using the new integral-based formulation. However, owing to the intrinsic limits of the Smagorinsky model, also in those results, the GIE is still remarkable therefore, the present paper presents a new formulation to the integral-based dynamic procedure for both one and two-coefficients mixed models (IDMM). The original contributions of the present paper can be summarised: (1) A theoretical analysis comparing the spectral errors for the differential and integral-based SSM, assessing that the errors are less relevant for the integral form; (2) The implementation of one and two parameters IDMM for the simulation of turbulence in a plane channel flow, assessing the reduction of the GIE and the good behaviour of the statistics that are compared with those of the other LES codes used in the LESinItaly project.     

Functional identities in upper triangular matrix rings revisited

The aim of this paper is to give an improvement of a result on functional identities in upper triangular matrix rings obtained by Eremita, which presents a short proof of Eremita’s result.     

Powers of the Catalan Generating Function and Lagrange''s 1770 Trinomial Equation Series

The Catalan numbers $1, 1, 2, 5, 14, 42, 132, 429, 1430, 4862,\ldots$ are given by $C(n)=\frac{1}{n+1}\binom{2n}{n}$ for $n\geq 0$. They are named for Eugene Catalan who studied them as early as 1838. They were also found by Leonhard Euler (1758), Nicholas von Fuss (1795), and Andreas von Segner (1758). The Catalan numbers have the binomial generating function $$\mathbf{C}(z) = \sum_{n=0}^{\infty}C(n)z^n = \frac{1 - \sqrt{1-4z}}{2z}$$ It is known that powers of the generating function $\mathbf{C}(z)$ are given by $$\mathbf{C}^a(z) = \sum_{n=0}^{\infty}\frac{a}{a+2n}\binom{a+2n}{n}z^n.$$ The above formula is not as widely known as it should be. We observe that it is an immediate, simple consequence of expansions first studied by J. L. Lagrange. Such series were used later by Heinrich August Rothe in 1793 to find remarkable generalizations of the Vandermonde convolution. For the equation $x^3 - 3x + 1 =0$, the numbers $\frac{1}{2k+1}\binom{3k}{k}$ analogous to Catalan numbers occur of course. Here we discuss the history of these expansions. and formulas due to L. C. Hsu and the author.     

Asymptotically linear fractional Schrödinger equations

By exploiting a variational technique based upon projecting over the Poho?aev manifold, we prove existence of positive solutions for a class of nonlinear fractional Schrödinger equations having a nonhomogenous nonautonomous asymptotically linear nonlinearity.