Geschichte der indogermanischen Sprachwissenschaft seit ihrer Begründung durch Franz Bopp.

Vol. 2, of the second part have imprint: Berlin, W. de Gruyter.

Anuario estadístico de Venezuela.

Vols. for < >-1894 have title: Anuario estadístico de los EE. UU. de Venezuela.

Obras completas ...

--t.I. Polemicas religiosas. Prologo del lte. Felix Romero; notas por Angel Pola.--t.II. Escritos politicos. Prologo por Angel Pola.--t.III. Letras y clencias. En peregrinacion, de Pomoca a Tepeji del rio, por Angel Pola y Aurelio J. Venegas; prologo del dr. Pornrio Parra.

Military review.

Latest issue consulted: Vol. 86, no. 1 (Jan.-Feb. 2006).

Iniciativa de Fomento de MOOC para el Desarrollo Un estudio del uso de MOOC para el desarrollo de la fuerza laboral y profesional en Colombia, Filipinas y Sudáfrica

El potencial del aprendizaje en línea proporciona desde hace mucho tiempo la esperanza de ofrecer educación de calidad a cualquier persona, en cualquier parte del mundo. El reciente desarrollo de cursos en línea masivos abiertos (MOOC, por sus siglas en inglés) representa un nuevo y emocionante avance, al ofrecer el desarrollo de habilidades profesionales y de enseñanza en los más altos niveles académicos a cualquier persona con los suficientes recursos mínimos para acceder a Internet. La investigación en la Iniciativa de Fomento de MOOC para el Desarrollo se diseñó para analizar el panorama de los MOOC en los países en vías de desarrollo y para comprender mejor las motivaciones de los usuarios de MOOC y proporcionar reflexiones sobre las ventajas y limitaciones de MOOC para los resultados de desarrollo de la fuerza laboral. Los hallazgos clave de este estudio desafían las creencias comunes sobre el uso de MOOC en los países en desarrollo, desafiando las caracterizaciones típicas de cómo las personas en los entornos con recursos limitados utilizan la tecnología para el aprendizaje y el empleo. De hecho, algunos de los hallazgos son tan contrarios a lo que se ha informado en los EE.UU. y otros entornos desarrollados que plantean nuevas preguntas para futuras investigaciones.

Iniciativa de Fomento de MOOC para el Desarrollo Un estudio del uso de MOOC para el desarrollo de la fuerza laboral y profesional en Colombia, Filipinas y Sudáfrica

El potencial del aprendizaje en línea proporciona desde hace mucho tiempo la esperanza de ofrecer educación de calidad a cualquier persona, en cualquier parte del mundo. El reciente desarrollo de cursos en línea masivos abiertos (MOOC, por sus siglas en inglés) representa un nuevo y emocionante avance, al ofrecer el desarrollo de habilidades profesionales y de enseñanza en los más altos niveles académicos a cualquier persona con los suficientes recursos mínimos para acceder a Internet. La investigación en la Iniciativa de Fomento de MOOC para el Desarrollo se diseñó para analizar el panorama de los MOOC en los países en vías de desarrollo y para comprender mejor las motivaciones de los usuarios de MOOC y proporcionar reflexiones sobre las ventajas y limitaciones de MOOC para los resultados de desarrollo de la fuerza laboral. Los hallazgos clave de este estudio desafían las creencias comunes sobre el uso de MOOC en los países en desarrollo, desafiando las caracterizaciones típicas de cómo las personas en los entornos con recursos limitados utilizan la tecnología para el aprendizaje y el empleo. De hecho, algunos de los hallazgos son tan contrarios a lo que se ha informado en los EE.UU. y otros entornos desarrollados que plantean nuevas preguntas para futuras investigaciones.

La generación del silencio (II). El éxodo del Mariel, 25 años después:un acercamiento a los escritores e intelectuales que abandonaron la Isla para ejercer la creación artística y la libertad de expresión

El éxodo del Mariel, 25 años después: Aunque el público y la crítica de EE UU no fueron muy receptivos con la obra literaria de los marielitos, esa situación no frenó sus ambiciones. The Mariel boatlift, 25 years later: Although the public and critics of the U.S. were not very receptive to the literary work of Mariel, that situation did not stop his ambitions.

Astrocyte-neuron signalling by synaptic stimulation in the ventrobasal thalamus

In the Ventrobasal (VB) thalamus, astrocytes are known to elicit NMDA-receptor mediated slow inward currents (SICs) spontaneously in neurons. Fluorescence imaging of astrocytes and patch clamp recordings from the thalamocortical (TC) neurons in the VB of 6-23 day old Wistar rats were performed. TC neurons exhibit spontaneous SICs at low frequencies (~0.0015Hz) that were inhibited by NMDA-receptor antagonists D-AP5 (50µM), and were insensitive to TTX (1µM) suggesting a non-neuronal origin. The effect of corticothalamic (CT) and sensory (Sen) afferent stimulation on astrocyte signalling was assessed by varying stimulus parameters. Moderate synaptic stimulation elicited astrocytic Ca2+ increases, but did not affect the incidence of spontaneous SICs. Prolonged synaptic stimulation induced a 265% increase in SIC frequency. This increase lasted over one hour after the cessation of synaptic stimulation, so revealing a Long Term Enhancement (LTE) of astrocyte-neuron signalling. LTE induction required group I mGluR activation. LTE SICs targeted NMDA-receptors located at extrasynaptic sites. LTE showed a developmental profile: from weeks 1-3, the SIC frequency was increased by an average 50%, 240% and 750% respectively. Prolonged exposure to glutamate (200µM) increased spontaneous SIC frequency by 1800%. This “chemical” form of LTE was prevented by the broad-spectrum excitatory amino acid transporter (EAAT) inhibitor TBOA (300µM) suggesting that glutamate uptake was a critical factor. My results therefore show complex glutamatergic signalling interactions between astrocytes and neurons. Furthermore, two previously unrecognised mechanisms of enhancing SIC frequency are described. The synaptically induced LTE represents a form of non-synaptic plasticity and a glial “memory” of previous synaptic activity whilst enhancement after prolonged glutamate exposure may represent a pathological glial signalling mechanism.

Adaptive sending rate over wireless mesh networks using SNR

Wireless Mesh Networks (WMNs) have emerged as a key technology for the next generation of wireless networking. Instead of being another type of ad-hoc networking, WMNs diversify the capabilities of ad-hoc networks. Several protocols that work over WMNs include IEEE 802.11a/b/g, 802.15, 802.16 and LTE-Advanced. To bring about a high throughput under varying conditions, these protocols have to adapt their transmission rate. In this paper, we have proposed a scheme to improve channel conditions by performing rate adaptation along with multiple packet transmission using packet loss and physical layer condition. Dynamic monitoring, multiple packet transmission and adaptation to changes in channel quality by adjusting the packet transmission rates according to certain optimization criteria provided greater throughput. The key feature of the proposed method is the combination of the following two factors: 1) detection of intrinsic channel conditions by measuring the fluctuation of noise to signal ratio via the standard deviation, and 2) the detection of packet loss induced through congestion. We have shown that the use of such techniques in a WMN can significantly improve performance in terms of the packet sending rate. The effectiveness of the proposed method was demonstrated in a simulated wireless network testbed via packet-level simulation.

A quality driven framework for adaptive video streaming in mobile wireless networks

The concern over the quality of delivering video streaming services in mobile wireless networks is addressed in this work. A framework that enhances the Quality of Experience (QoE) of end users through a quality driven resource allocation scheme is proposed. To play a key role, an objective no-reference quality metric, Pause Intensity (PI), is adopted to derive a resource allocation algorithm for video streaming. The framework is examined in the context of 3GPP Long Term Evolution (LTE) systems. The requirements and structure of the proposed PI-based framework are discussed, and results are compared with existing scheduling methods on fairness, efficiency and correlation (between the required and allocated data rates). Furthermore, it is shown that the proposed framework can produce a trade-off between the three parameters through the QoE-aware resource allocation process.

Quality-driven resource utilization methods for video streaming in wireless communication networks

This research is focused on the optimisation of resource utilisation in wireless mobile networks with the consideration of the users’ experienced quality of video streaming services. The study specifically considers the new generation of mobile communication networks, i.e. 4G-LTE, as the main research context. The background study provides an overview of the main properties of the relevant technologies investigated. These include video streaming protocols and networks, video service quality assessment methods, the infrastructure and related functionalities of LTE, and resource allocation algorithms in mobile communication systems. A mathematical model based on an objective and no-reference quality assessment metric for video streaming, namely Pause Intensity, is developed in this work for the evaluation of the continuity of streaming services. The analytical model is verified by extensive simulation and subjective testing on the joint impairment effects of the pause duration and pause frequency. Various types of the video contents and different levels of the impairments have been used in the process of validation tests. It has been shown that Pause Intensity is closely correlated with the subjective quality measurement in terms of the Mean Opinion Score and this correlation property is content independent. Based on the Pause Intensity metric, an optimised resource allocation approach is proposed for the given user requirements, communication system specifications and network performances. This approach concerns both system efficiency and fairness when establishing appropriate resource allocation algorithms, together with the consideration of the correlation between the required and allocated data rates per user. Pause Intensity plays a key role here, representing the required level of Quality of Experience (QoE) to ensure the best balance between system efficiency and fairness. The 3GPP Long Term Evolution (LTE) system is used as the main application environment where the proposed research framework is examined and the results are compared with existing scheduling methods on the achievable fairness, efficiency and correlation. Adaptive video streaming technologies are also investigated and combined with our initiatives on determining the distribution of QoE performance across the network. The resulting scheduling process is controlled through the prioritization of users by considering their perceived quality for the services received. Meanwhile, a trade-off between fairness and efficiency is maintained through an online adjustment of the scheduler’s parameters. Furthermore, Pause Intensity is applied to act as a regulator to realise the rate adaptation function during the end user’s playback of the adaptive streaming service. The adaptive rates under various channel conditions and the shape of the QoE distribution amongst the users for different scheduling policies have been demonstrated in the context of LTE. Finally, the work for interworking between mobile communication system at the macro-cell level and the different deployments of WiFi technologies throughout the macro-cell is presented. A QoEdriven approach is proposed to analyse the offloading mechanism of the user’s data (e.g. video traffic) while the new rate distribution algorithm reshapes the network capacity across the macrocell. The scheduling policy derived is used to regulate the performance of the resource allocation across the fair-efficient spectrum. The associated offloading mechanism can properly control the number of the users within the coverages of the macro-cell base station and each of the WiFi access points involved. The performance of the non-seamless and user-controlled mobile traffic offloading (through the mobile WiFi devices) has been evaluated and compared with that of the standard operator-controlled WiFi hotspots.

About the Concept of Weights of WLTE(k) Estimators

2002 Mathematics Subject Classification: 62F35, 62F15.

Ensuring QoE in contemporary mobile networks for video content distribution

A framework that aims to best utilize the mobile network resources for video applications is presented in this paper. The main contribution of the work proposed is the QoE-driven optimization method that can maintain a desired trade-off between fairness and efficiency in allocating resources in terms of data rates to video streaming users in LTE networks. This method is concerned with the control of the user satisfaction level from the service continuity's point of view and applies appropriate QoE metrics (Pause Intensity and variations) to determine the scheduling strategies in combination with the mechanisms used for adaptive video streaming such as 3GP/MPEG-DASH. The superiority of the proposed algorithms are demonstrated, showing how the resources of a mobile network can be optimally utilized by using quantifiable QoE measurements. This approach can also find the best match between demand and supply in the process of network resource distribution.

Adaptive sending rate over wireless mesh networks using SNR

Wireless Mesh Networks (WMNs) have emerged as a key technology for the next generation of wireless networking. Instead of being another type of ad-hoc networking, WMNs diversify the capabilities of ad-hoc networks. Several protocols that work over WMNs include IEEE 802.11a/b/g, 802.15, 802.16 and LTE-Advanced. To bring about a high throughput under varying conditions, these protocols have to adapt their transmission rate. This paper proposes a scheme to improve channel conditions by performing rate adaptation along with multiple packet transmission using packet loss and physical layer condition. Dynamic monitoring, multiple packet transmission and adaptation to changes in channel quality by adjusting the packet transmission rates according to certain optimization criteria provided greater throughput. The key feature of the proposed method is the combination of the following two factors: 1) detection of intrinsic channel conditions by measuring the fluctuation of noise to signal ratio via the standard deviation, and 2) the detection of packet loss induced through congestion. The authors show that the use of such techniques in a WMN can significantly improve performance in terms of the packet sending rate. The effectiveness of the proposed method was demonstrated in a simulated wireless network testbed via packet-level simulation.

Szolgáltatóváltás a magyar lakossági árampiacon 2008-ban

Tanulmányunkban a 2008. január 1-jétől bekövetkező árampiaci liberalizáció lakossági fogyasztókra vonatkozó - várható - hatását elemezzük. Elméleti modellünkben azzal a feltevéssel élünk, hogy a heterogén fogyasztók szolgáltatóváltása költséges, és a fogyasztókért eltérő méretű vállalatok árversenyt folytatnak. A fogyasztói döntéseket egy szolgáltatóváltási függvénnyel írjuk le. Miután bemutatjuk, hogy ebben a modellben nincs tiszta Nash-egyensúly, egy másik egyensúlyfogalmat, az aláígérés-biztos egyensúly fogalmát használjuk annak megállapítására, hogy milyen kimenetei lehetnek a modellnek. Az aláígérés-biztos egyensúly feltételeinek megadása után elemezzük az elméleti modellt, amelynek megoldását numerikus módszerekkel a modell kalibrálása után végezzük el. A modell megoldása során arra a következtetésre jutottunk, hogy a lakossági piacon jelentős áremelkedés várható, amelyet két tényező indukál. Egyrészt a szolgáltatóváltási költségek léte, másrészt a piac alacsony szintű megtámadhatósága.