Mejores prácticas de desarrollo profesional docente en Estados Unidos

This paper discusses best practices in teachers’ professional development (PD) in the United States (U.S.). We begin by presenting a conceptual framework for effective professional development, which suggests five key features that make professional development effective—content focus, active learning, coherence, sustained duration, and collective participation. We then describe the findings from recent U.S. research that has tested the five features, with an emphasis on the results of rigorous randomized control trials. We discuss several insights gained from this work and that have helped refine the framework. They are that (a) changing procedural classroom behavior is easier than improving content knowledge or inquiry-oriented instruction techniques; (b) teachers vary in response to the same PD; (c) PD is more successful when it is explicitly linked to classroom lessons; (d) PD research and implementation must allow for urban contexts (e.g., student and teacher mobility); and (e) leadership plays a key role in supporting and encouraging teachers to implement in the classroom the ideas and strategies they learned in the PD. We then examine three major trends in how professional development for teachers is evolving in the U.S.—a move away from short workshops, linking teacher PD to evaluations, and the use of video technology to improve and monitor the effects of PD. Finally, we discuss the challenges faced by districts and schools in implementing effective professional development.Este artículo analiza las mejores prácticas de desarrollo profesional docente (DPD) en los Estados Unidos de América (USA). Comenzamos presentando un marco conceptual sobre DPD, que sugiere la existencia de cinco características clave que favorecen un DPD efectivo: foco en el contenido, aprendizaje activo, coherencia, duración sostenida, y participación colectiva. Continuamos describiendo los resultados de recientes investigaciones que han puesto a prueba dichas cinco características en USA, enfatizando los resultados de rigurosos estudios experimentales aleatorizados. Discutimos las lecciones aprendidas a partir de dichos estudios, que nos han permitido refinar nuestro marco teórico sobre el DPD efectivo. Hemos aprendido que (a) cambiar el comportamiento de los profesores en clase es más fácil que mejorar sus conocimientos disciplinares o las estrategias instruccionales de alto nivel; (b) los profesores varían en respuesta al mismo DPD; (c) DPD es más exitoso cuando está explícitamente conectado con la práctica docente; (d) la investigación y la implementación del DPD debe tener en cuenta las condiciones de las áreas urbanas (e.g., la movilidad de estudiantes y profesores); y (e) los líderes juegan un rol fundamental apoyando y animando a los profesores para que apliquen en sus clases las ideas y estrategias aprendidas en DPD. Después examinamos tres tendencias generales en la evaluación reciente del DPD en USA—un descenso en el uso de cursos y talleres de corta duración, la conexión del DPD con las evaluaciones del profesorado, y el uso de video-tecnología para mejorar y supervisar los efectos del DPD. Finalmente, discutimos las dificultades que los distritos y las escuelas encuentran para implementar DPD efectivo

Uniaxial and biaxial soft deformations of nematic elastomers

We give a geometric interpretation of the soft elastic deformation modes of nematic elastomers, with explicit examples, for both uniaxial and biaxial nematic order. We show the importance of body rotations in this non-classical elasticity and how the invariance under rotations of the reference and target states gives soft elasticity (the Golubovic and Lubensky theorem). The role of rotations makes the Polar Decomposition Theorem vital for decomposing general deformations into body rotations and symmetric strains. The role of the square roots of tensors is discussed in this context and that of finding explicit forms for soft deformations (the approach of Olmsted).Comment: 10 pages, 10 figures, RevTex, AmsTe

Jamming Model for the Extremal Optimization Heuristic

Extremal Optimization, a recently introduced meta-heuristic for hard optimization problems, is analyzed on a simple model of jamming. The model is motivated first by the problem of finding lowest energy configurations for a disordered spin system on a fixed-valence graph. The numerical results for the spin system exhibit the same phenomena found in all earlier studies of extremal optimization, and our analytical results for the model reproduce many of these features.Comment: 9 pages, RevTex4, 7 ps-figures included, as to appear in J. Phys. A, related papers available at http://www.physics.emory.edu/faculty/boettcher

Shape programming for narrow ribbons of nematic elastomers

Using the theory of Γ-convergence, we derive from three-dimensional elasticity new one-dimensional models for non-Euclidean elastic ribbons, i.e., ribbons exhibiting spontaneous curvature and twist. We apply the models to shape-selection problems for thin films of nematic elastomers with twist and splay-bend texture of the nematic director. For the former, we discuss the possibility of helicoid-like shapes as an alternative to spiral ribbons

Homogenization in magnetic-shape-memory polymer composites

Magnetic-shape-memory materials (e.g. specific NiMnGa alloys) react with a large change of shape to the presence of an external magnetic field. As an alternative for the difficult to manifacture single crystal of these alloys we study composite materials in which small magnetic-shape-memory particles are embedded in a polymer matrix. The macroscopic properties of the composite depend strongly on the geometry of the microstructure and on the characteristics of the particles and the polymer. We present a variational model based on micromagnetism and elasticity, and derive via homogenization an effective macroscopic model under the assumption that the microstructure is periodic. We then study numerically the resulting cell problem, and discuss the effect of the microstructure on the macroscopic material behavior. Our results may be used to optimize the shape of the particles and the microstructure.Comment: 17 pages, 4 figure

Fabrication of multiphasic and regio-specifically functionalized PRINT ® particles of controlled size and shape

Using Particle Replication In Nonwetting Templates (PRINT®) technology, multiphasic and regio-specifically functionalized shape-controlled particles have been fabricated that include end-labeled particles via post-functionalization; biphasic Janus particles that integrate two compositionally different chemistries into a single particle; and more complex multiphasic shape-specific particles. Controlling the anisotropic distribution of matter within a particle creates an extra parameter in the colloidal particle design, providing opportunities to generate advanced particles with versatile and tunable compositions, properties, and thus functionalities. Owing to their robust characteristics, these multiphasic and regio-specifically functionalized PRINT particles should be promising platforms for applications in life science and materials science

Toward the PSTN/Internet Inter-Networking--Pre-PINT Implementations

This document contains the information relevant to the development of the inter-networking interfaces underway in the Public Switched Telephone Network (PSTN)/Internet Inter-Networking (PINT) Working Group. It addresses technologies, architectures, and several (but by no means all) existing pre-PINT implementations of the arrangements through which Internet applications can request and enrich PSTN telecommunications services. The common denominator of the enriched services (a.k.a. PINT services) is that they combine the Internet and PSTN services in such a way that the Internet is used for non-voice interactions, while the voice (and fax) are carried entirely over the PSTN. One key observation is that the pre-PINT implementations, being developed independently, do not inter-operate. It is a task of the PINT Working Group to define the inter-networking interfaces that will support inter-operation of the future implementations of PINT services

Local invertibility in Sobolev spaces with applications to nematic elastomers and magnetoelasticity

We define a class of deformations in W^1,p(\u3a9,R^n), p>n 121, with positive Jacobian that do not exhibit cavitation. We characterize that class in terms of the non-negativity of the topological degree and the equality between the distributional determinant and the pointwise determinant of the gradient. Maps in this class are shown to satisfy a property of weak monotonicity, and, as a consequence, they enjoy an extra degree of regularity. We also prove that these deformations are locally invertible; moreover, the neighbourhood of invertibility is stable along a weak convergent sequence in W^1,p, and the sequence of local inverses converges to the local inverse. We use those features to show weak lower semicontinuity of functionals defined in the deformed configuration and functionals involving composition of maps. We apply those results to prove existence of minimizers in some models for nematic elastomers and magnetoelasticity

Scalable Manufacture of Built-to-Order Nanomedicine: Spray-Assisted Layer-by-Layer Functionalization of PRINT Nanoparticles

Scalable methods, PRINT particle fabrication, and spray-assisted Layer-by-Layer deposition are combined to generate uniform and functional nanotechnologies with precise control over composition, size, shape, and surface functionality. A modular and tunable approach towards design of built-to-order nanoparticle systems, spray coating on PRINT particles is demonstrated to achieve technologies capable of targeted interactions with cancer cells for applications in drug delivery.National Cancer Institute (U.S.) (Center for Cancer Nanotechnology Excellence Grant 5 U54 CA151884-02)National Science Foundation (U.S.). Graduate Research FellowshipNatural Sciences and Engineering Research Council of Canada (Postdoctoral Fellowship