732 research outputs found
Impacto de estrategias orientadoras en la modalidad mixta a través de ejes fundamentales de acción
En este trabajo se propone la creación de estrategias de orientación para proporcionar apoyo en la orientación psicológica e información profesional y laboral, interviniendo en forma individual, grupal, masiva, en línea, especializada, en pares y mixta. Así mismo se presentan acciones que dependen de tres ejes fundamentales: de prevención, formación e intervención. Los resultados exploratorios con su respectiva metodología permiten identificar desde los alumnos en riesgo de reprobación hasta aquellos propensos a abandonar la escuela y, con esto, reducir exitosamente problemática constante en la modalidad mixta del bachillerato
Spectra of infinite graphs via freeness with amalgamation
We use tools from free probability to study the spectra of Hermitian
operators on infinite graphs. Special attention is devoted to universal
covering trees of finite graphs. For operators on these graphs we derive a new
variational formula for the spectral radius and provide new proofs of results
due to Sunada and Aomoto using free probability.
With the goal of extending the applicability of free probability techniques
beyond universal covering trees, we introduce a new combinatorial product
operation on graphs and show that, in the non-commutative probability context,
it corresponds to the notion of freeness with amalgamation. We show that Cayley
graphs of amalgamated free products of groups, as well as universal covering
trees, can be constructed using our graph product.Comment: 45 pages, 4 figures, comments welcome; v2:Key references and new
results have been included. In particular, we realized that a result on the
band structure of the spectrum, which we believed to be new, had actually
appeared in previous literature (see the bibliographic note just before Sec
1.1); v3:Minor edits, added discussions, generalized Thm 1.6 from adjacency
matrices to graph Jacobi matrice
Trichoscopy of Dark Scalp
Abstract Trichoscopy (dermoscopy of the hair and scalp) is a technique that improves diagnostic accuracy and follow-up with hair and scalp disorders. Although several studies of trichoscopy have been made in Caucasian and Asian populations, little has been published regarding trichoscopy findings in skin of color, despite the great prevalence of hair diseases in populations with this kind of skin. The aim of this review was to describe the trichoscopic features of normal scalp and of hair disorders in patients with dark skin phototypes. This will help dermatologists to distinguish between unique trichoscopic features of dark skin, and allow them to provide more accurate diagnoses and treatments for these patients
Global Convergence of Hessenberg Shifted QR II: Numerical Stability
We develop a framework for proving rapid convergence of shifted QR algorithms
which use Ritz values as shifts, in finite arithmetic. Our key contribution is
a dichotomy result which addresses the known forward-instability issues
surrounding the shifted QR iteration [Parlett and Le 1993]: we give a procedure
which provably either computes a set of approximate Ritz values of a Hessenberg
matrix with good forward stability properties, or leads to early decoupling of
the matrix via a small number of QR steps.
Using this framework, we show that the shifting strategy introduced in Part I
of this series [Banks, Garza-Vargas, and Srivastava 2021] converges rapidly in
finite arithmetic with a polylogarithmic bound on the number of bits of
precision required, when invoked on matrices of controlled eigenvector
condition number and minimum eigenvalue gap
The Limited Effect of Graphic Elements in Video and Augmented Reality on Children’s Listening Comprehension
There is currently significant interest in the use of instructional strategies in learning environments thanks to the emergence of new multimedia systems that combine text, audio, graphics and video, such as augmented reality (AR). In this light, this study compares the effectiveness of AR and video for listening comprehension tasks. The sample consisted of thirty-two elementary school students with different reading comprehension. Firstly, the experience, instructions and objectives were introduced to all the students. Next, they were divided into two groups to perform activities—one group performed an activity involving watching an Educational Video Story of the Laika dog and her Space Journey available by mobile devices app Blue Planet Tales, while the other performed an activity involving the use of AR, whose contents of the same history were visualized by means of the app Augment Sales. Once the activities were completed participants answered a comprehension test. Results (p = 0.180) indicate there are no meaningful differences between the lesson format and test performance. But there are differences between the participants of the AR group according to their reading comprehension level. With respect to the time taken to perform the comprehension test, there is no significant difference between the two groups but there is a difference between participants with a high and low level of comprehension. To conclude SUS (System Usability Scale) questionnaire was used to establish the measure usability for the AR app on a smartphone. An average score of 77.5 out of 100 was obtained in this questionnaire, which indicates that the app has fairly good user-centered design
Why doesn't my wind farm produce what I expected? A guide to wind farm performance assessment
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