Nikishin systems are perfect

K. Mahler introduced the concept of perfect systems in the general theory he developed for the simultaneous Hermite-Pade approximation of analytic functions. We prove that Nikishin systems are perfect providing, by far, the largest class of systems of functions for which this important property holds. As consequences, in the context of Nikishin systems, we obtain: an extension of Markov's theorem to simultaneous Hermite-Pade approximation, a general result on the convergence of simultaneous quadrature rules of Gauss-Jacobi type, the logarithmic asymptotics of general sequences of multiple orthogonal polynomials, and an extension of the Denisov-Rakhmanov theorem for the ratio asymptotics of mixed type multiple orthogonal polynomials.Comment: 39 page

Mieropaleontologieal study of an holoeene eoastal peat in the Ría de Ares (A Coruña, España)

[Resumen] El análisis de polen, diatomeas y foraminíferos de un sedimento litoral en la Ría de Ares (A Coruña, España) ha permitido interpretaciones paleoambientales comparables. Se trata de un sedimento turboso con macrorrestos vegetales. El análisis micropaleontológico de este nivel y las dataciones absolutas sitúan la formación del mismo en el período Subboreal. La lectura paleoecológica obtenida a través del estudio micropaleontológico nos permite reconstituir dos paleoambientes fundamentalmente: un medio continental vegetado y un ambiente con condiciones salobres, consecuencia del aumento del nivel del mar.[Abstract] Pollen, diatoms and foraminifera from a raised marine sediment of the Ría de Ares (A Coruña, Spain) area produced comparable paleoenvironntental interpretations. It is an organic formation with peat associated with numerous vegetal rests. The micropaleontological analysis of this level and the absolute dating, place its formation in the Subboreal periodo The paleoecological reading obtained from a micropaleontological study allows us to reconstitute two basic paleoenvironments: a vegetal continental environment and an environment with salty conditions, as a consequence of the sea level increas

Effects of direct instruction and strategy modelling on upper-primary students' writing development

Strategy-focused instruction is one of the most effective approaches to improve writing skills. It aims to teach developing writers strategies that give them executive control over their writing processes. Programs under this kind of instruction tend to have multiple components that include direct instruction, modeling and scaffolded practice. This multi-component nature has two drawbacks: it makes implementation challenging due to the amount of time and training required to perform each stage, and it is difficult to determine the underlying mechanisms that contribute to its effectiveness. To unpack why strategy-focused instruction is effective, we explored the specific effects of two key components: direct teaching of writing strategies and modeling of strategy use. Six classes (133 students) of upper-primary education were randomly assigned to one of the two experimental conditions, in which students received instruction aimed at developing effective strategies for planning and drafting, or control group with no strategy instruction: Direct Instruction (N = 46), Modeling (N = 45), and Control (N = 42). Writing performance was assessed before the intervention and immediately after the intervention with two tasks, one collaborative and the other one individual to explore whether differential effects resulted from students writing alone or in pairs. Writing performance was assessed through reader-based and text-based measures of text quality. Results at post-test showed similar improvement in both intervention conditions, relatively to controls, in all measures and in both the collaborative and the individual task. No statistically significant differences were observed between experimental conditions. These findings suggest that both components, direct teaching and modeling, are equally effective in improving writing skills in upper primary students, and these effects are present even after a short training

Autolytic changes involving proteolytic enzymes on Atlantic salmon (Salmo salar) preserved by hyperbaric storage

he effect of hyperbaric storage (HS, 50–75 MPa at 10–37 °C) on proteolytic enzymes and muscle proteins of Atlantic salmon (Salmo salar) was assessed and compared to atmospheric pressure (AP, 0.1 MPa) at the same storage temperature and refrigeration (AP, 5 °C). Generally, activities of acid phosphatase, cathepsin B and D, and calpains decreased when compared to fresh salmon, with a more’ pronounced effect of storage temperature of 37 °C in HS/AP samples. However, activity recovery was observed for some enzymes, as the case of cathepsins B and D, and calpains, whose showed an increase of residual activity for samples stored at 60 MPa/10 °C and 75 MPa/25 °C after 50 and 25 d, respectively. A pronounced increase of myofibrillar fragmentation index (MFI) was observed at 75 MPa (25/37 °C) after 10 d (3.2-/4.3-fold, respectively). Otherwise, at 60 MPa/10 °C, a decrease of MFI values was observed after 50 d of storage. For sarcoplasmic proteins, no effect was observed at 60 MPa/10 °C during 30 d of storage, with a slight increase after 50 d. At 75 MPa/25 °C, a decrease of sarcoplasmic proteins content (46%) was obtained after 10 d with no further changes during the 25 d of storage.publishe

Technology behaviors in education innovation

Change and improvement are two keywords embedded in innovation in general (OECD, 2005) and, in particular, in teaching and learning innovation (Miles, 1964). Based on those two keywords, educational innovation could be defined as “the application of one idea that produces a planned change in educational processes, services, or products, then leading to an improvement in learning goals”. The role of the computer in educational innovation is seen as a facilitating tool, as both educational innovation and computation address the same topic, i.e. “Knowledge”. The computer's capability to manage information makes it an ideal tool to potentiate different implementations in teaching and learning contexts. The several distinct ways teachers and students interact are oriented by teaching methods. This means the computer may be used to: improve existing methods for teacher-students interaction, e.g. traditional lectures; enable alternative methods that are difficult to apply under current conditions, e.g. personalized learning; create new methods, e.g. flipped teaching; or, in addition, analyse data generated from teacher-students interactions and help in the learning improvement decision-making process..

Evaluating effects of different forms of revision instruction in upper-primary students

p. 1741-1767This study aimed to establish (a) whether teaching students revision skills provides beneft over and above teaching strategies for setting explicit goals for the communicative efect of their text, and (b) whether teaching students to adopt specifc revision strategies provides benefts over revision instruction that focusses on increasing students’ awareness of audience needs. Six classes of Spanish sixth-grade students (N=107, 11–12 years) were randomly assigned to one of three conditions. In all three conditions students were taught to set communicative goals. Students in the Strategy Focused condition were then taught a 6-step revision strategy. Students in the Reader Focused condition observed a reader trying to comprehend a text and suggesting ways in which it might be improved. Students in a control condition continued with goal-setting practice. Students’ writing performance was assessed through composition and revision tasks before and immediately after intervention, 2 months post-intervention, and for transfer to an untaught genre. Writing performance and revision skills improved more in the two revision-instruction conditions than for students in the control condition. The improvements were large, persistent and transferred to a diferent type of text. We found no statistically signifcant diferences between the two revision conditions. Findings suggest that specifc revision instruction benefts sixth-grade students’ writing performance and revision skills, but that strategy-focused and reader-focused approaches are similarly efectiveS