Propuesta curricular de hip??tesis de progresi??n para conceptos estructurantes de ecolog??a

Resumen en ingl??s

El papel de la pr??ctica en el desarrollo de la competencia motriz infantil : la hip??tesis de la variabilidad

Se aplica la hip??tesis de la variabilidad al practicar en el aprendizaje motor infantil de la teor??a del esquema de R. Achmidt. Se estructura en tres partes. En la primera se revisan los diferentes modelos explicativos del desrrollo motor. En la segunda se analiza la Teor??a del esquema de Richard Schmidt y su hip??tesis de variabilidad al practicar. En la tercera se presentan diferentes estudios experimentales a partir de los supuestos evaluados en las otras dos partes. Se analizan diferentes aspectos de la variabilidad al practicar (parametros variados, tipo de organizaci??n). Se estudia el papel de las estrategias instructivas aunadas a la pr??ctica variable aleatoria. Investigaci??n cuantitativa y cualitativa. Los resultados apoyan la hip??tesis de Schmidt y destacan la importancia de la organizaci??n de la pr??tica variable en la infancia. Se sugieren propuestas de actuaci??n para el futuro.

Aplicaci??n del m??todo Bootstrap al contraste de hip??tesis en la investigaci??n educativa

Resumen del autor. Resumen en castellano e ingl??s. Este art??culo se incluye en el monogr??fico 'Educaci??n social'

Una hip??tesis sobre las Novelas Ejemplares

An??lisis de la afinidad y concordancia entre las Novelas Ejemplares con las obras esc??nicas de Cervantes. Se baraja la posibilidad de que las Novelas Ejemplares sean antiguas comedias de Cervantes, que m??s tarde ??ste refundi?? en prosa para adaptarlas al gusto de la ??poca.

Contraste de la hip??tesis de se??alizaci??n : una panor??mica

Resumen basado en el de la publicaci??n. Notas a pie de p??gina

El giro pedag??gico en la investigaci??n sobre la transferencia interling????stica : repasando las hip??tesis de interdependencia y del umbral ling????stico

Resumen basado en el de la publicaci??n

Proteomic analysis of resting and thrombin-stimulated platelets reveals the translocation and functional relevance of HIP-55 in platelets

The platelet surface is a dynamic interface that changes rapidly in response to stimuli to coordinate the formation of thrombi at sites of vascular injury. Tight control is essential as loss of organisation may result in the inappropriate formation of thrombi (thrombosis) or excessive bleeding. In this paper we describe the comparative analysis of resting and thrombin-stimulated platelet membrane proteomes and associated proteins to identify proteins important to platelet function. Surface proteins were labelled using a biotin tag and isolated by NeurtrAvidin affinity chromatography. Liquid phase IEF and SDS-PAGE were used to separate proteins, and bands of increased intensity in the stimulated platelet fractions were digested and identified by FT-ICR mass spectrometry. Novel proteins were identified along with proteins known to be translocated to the platelet surface. Furthermore, many platelet proteins revealed changes in location associated with function, including G6B and Hip-55. HIP-55 is an SH3-binding protein important in T-cell receptor signalling. Further analysis of HIP-55 revealed that this adaptor protein becomes increasingly associated with both Syk and integrin beta 3 upon platelet activation. Analysis of HIP-55 deficient platelets revealed reduced fibrinogen binding upon thrombin stimulation, suggesting HIP-55 to be an important regulator of platelet function.

Modeling energy consumption of dual-hop relay based MAC protocols in ad hoc networks

Given that the next and current generation networks will coexist for a considerable period of time, it is important to improve the performance of existing networks. One such improvement recently proposed is to enhance the throughput of ad hoc networks by using dual-hop relay-based transmission schemes. Since in ad hoc networks throughput is normally related to their energy consumption, it is important to examine the impact of using relay-based transmissions on energy consumption. In this paper, we present an analytical energy consumption model for dual-hop relay-based medium access control (MAC) protocols. Based on the recently reported relay-enabled Distributed Coordination Function (rDCF), we have shown the efficacy of the proposed analytical model. This is a generalized model and can be used to predict energy consumption in saturated relay-based ad hoc networks. This model can predict energy consumption in ideal environment and with transmission errors. It is shown that using a relay results in not only better throughput but also better energy efficiency. Copyright (C) 2009 Rizwan Ahmad et al.

Multi-hop amplify-and-forward relaying cooperation in the presence of I/Q imbalance

In this paper, multi-hop cooperative networks implementing channel state information (CSI)-assisted amplify-and-forward (AF) relaying in the presence of in-phase and quadrature-phase (I/Q) imbalance are investigated. We propose a compensation algorithm for the I/Q imbalance. The performance of the multi-hop CSI-assisted AF cooperative networks with and without compensation for I/Q imbalance in Nakagami-m fading environment is evaluated in terms of average symbol error probability. Numerical results are provided and show that the proposed compensation method can effectively mitigate the impact of I/Q imbalance.

Dual-hop amplify-and-forward cooperative relaying in the presence of Tx and Rx in-phase and quadrature-phase imbalance

In this study, dual-hop channel state information-assisted amplify-and-forward (AF) cooperative systems in the presence of in-phase and quadrature-phase (I/Q) imbalance, which refers to the mismatch between components in the I and Q branches, are investigated. First, the authors analyse the performance of the considered AF cooperative protocol without compensation for the I/Q imbalance as the benchmark. Then, a compensation algorithm for the I/Q imbalance is proposed, which makes use of the received signals at the destination, from the source and the relay nodes, together with their conjugations to detect the transmitted signal. Moreover, the authors study the considered AF cooperative system implemented with the opportunistic relay selection and the proposed compensation mechanism for the I/Q imbalance. The performance of the AF cooperative system under study is evaluated in terms of average symbol error probability, which is derived by considering transmission in a Rayleigh fading environment. Numerical results are provided and show that the proposed compensation algorithm can efficiently mitigate the effect of the I/Q imbalance. On the other hand, it is observed that the AF cooperative system with opportunistic relay selection acquires a performance gain beyond that without relay selection.

Fast heuristics for the Steiner tree problem with revenues, budget and hop constraints

This article describes and compares three heuristics for a variant of the Steiner tree problem with revenues, which includes budget and hop constraints. First, a greedy method which obtains good approximations in short computational times is proposed. This initial solution is then improved by means of a destroy-and-repair method or a tabu search algorithm. Computational results compare the three methods in terms of accuracy and speed. (C) 2007 Elsevier B.V. All rights reserved.