A Discussion of Thin Client Technology for Computer Labs

Computer literacy is not negotiable for any professional in an increasingly computerised environment. Educational institutions should be equipped to provide this new basic training for modern life. Accordingly, computer labs are an essential medium for education in almost any field. Computer labs are one of the most popular IT infrastructures for technical training in primary and secondary schools, universities and other educational institutions all over the world. Unfortunately, a computer lab is expensive, in terms of both initial purchase and annual maintenance costs, and especially when we want to run the latest software. Hence, research efforts addressing computer lab efficiency, performance or cost reduction would have a worldwide repercussion. In response to this concern, this paper presents a survey on thin client technology for computer labs in educational environments. Besides setting out the advantages and drawbacks of this technology, we aim to refute false prejudices against thin clients, identifying a set of educational scenarios where thin clients are a better choice and others requiring traditional solutions

Fuzzy memoization for floating-point multimedia applications

Instruction memoization is a promising technique to reduce the power consumption and increase the performance of future low-end/mobile multimedia systems. Power and performance efficiency can be improved by reusing instances of an already executed operation. Unfortunately, this technique may not always be worth the effort due to the power consumption and area impact of the tables required to leverage an adequate level of reuse. In this paper, we introduce and evaluate a novel way of understanding multimedia floating-point operations based on the fuzzy computation paradigm: performance and power consumption can be improved at the cost of small precision losses in computation. By exploiting this implicit characteristic of multimedia applications, we propose a new technique called tolerant memoization. This technique expands the capabilities of classic memoization by associating entries with similar inputs to the same output. We evaluate this new technique by measuring the effect of tolerant memoization for floating-point operations in a low-power multimedia processor and discuss the trade-offs between performance and quality of the media outputs. We report energy improvements of 12 percent for a set of key multimedia applications with small LUT of 6 Kbytes, compared to 3 percent obtained using previously proposed techniques.Peer ReviewedPostprint (published version

Initial results on fuzzy floating point computation for multimedia processors

During the recent years, the market of mid/low-end portable systems such as PDAs or mobile digital phones have experimented a revolution in both selling volume and features as handheld devices incorporate Multimedia applications. This fact brings to an increase in the computational demands of the devices, while still having the limitation of power (and energy) consumption. Instruction memoization is a promising technique to help alleviate the problem of power consumption of expensive functional units such as the floating-point one. Unfortunately, this technique could be energy-inefficient for low-end systems due to the additional power consumption of the relatively big tables required. In this paper we present a novel way of understanding multimedia floating point operations based on the fuzzy computation paradigm: losses in the computation precision may exchange performance for negligible errors in the output. Exploiting the implicit characteristics of media FP computation, we propose a new technique called fuzzy memoization. Fuzzy memoization expands the capabilities of classic memoization by attaching entries with similar inputs to the same output. We present a case of study for a SH4 like processor and report good performance and power-delay improvements with feasible hardware requirements.Peer ReviewedPostprint (published version

Fundamental finite key limits for information reconciliation in quantum key distribution

The security of quantum key distribution protocols is guaranteed by the laws of quantum mechanics. However, a precise analysis of the security properties requires tools from both classical cryptography and information theory. Here, we employ recent results in non-asymptotic classical information theory to show that information reconciliation imposes fundamental limitations on the amount of secret key that can be extracted in the finite key regime. In particular, we find that an often used approximation for the information leakage during one-way information reconciliation is flawed and we propose an improved estimate

An information reconciliation protocol for secret-key agreement with small leakage

We report on a variant of the so-called Cascade protocol that is well-known for its usage as information reconciliation protocol in quantum cryptography. A theoretical analysis of the optimal size of the parity check blocks is provided. We obtain a very small leakage which is for block sizes of 2^16 typically only 2.5% above the Shannon limit, and notably, this holds for a QBER between 1% and 50%. For a QBER between 1% and 6% the leakage is only 2% above the Shannon limit. As comparison, the leakage of the original Cascade algorithm is 20% (40%) above the Shannon limit for a QBER of 10% (35%)

Influence of the economic cycle on the determinants of nascent entrepreneurial activity. An empirical analysis of the Spanish case

This paper explores the contribution of a selection of elements representative of human capital and perception as determinants of entrepreneurship in different stages of the economic cycle. The results confirm the significance of self efficacy, the perception of opportunities, and the fear of failure, and highlight the importance of personal knowledge of entrepreneurs. They remain influential in different economic times in which their analyses have been replicated, although some differences are felt that point to, in contraction periods, a loss of influence of the confidence in one’s own abilities, compared to an increase in the case of judgment on the existence of opportunities in the environment, and in the case of the presence of entrepreneurs in the surrounding context. In contrast, the behavior of the fear of failure, as a barrier to entrepreneurship, remains unchanged in an adverse context with respect to a positive context due to reduced opportunity costs

Influencia del ciclo económico sobre los determinantes de la actividad emprendedora naciente. Un análisis empírico del caso español

This paper explores the contribution of a selection of elements representative of human capital and perception as determinants of entrepreneurship in different stages of the economic cycle. The results confirm the significance of selfefficacy, the perception of opportunities, and the fear of failure, and highlight the importance of personal knowledge of entrepreneurs. They remain influential in different economic times in which their analyses have been replicated, although some differences are felt that point to, in contraction periods, a loss of influence of the confidence in one’s own abilities, compared to an increase in the case of judgment on the existence of opportunities in the environment, and in the case of the presence of entrepreneurs in the surrounding context. In contrast, the behavior of the fear of failure, as a barrier to entrepreneurship, remains unchanged in an adverse context with respect to a positive context due to reduced opportunity costs.Este trabajo explora la contribución de una selección de elementos representativos de capital humano y de percepción como determinantes de la creación de empresas ante distintas etapas del ciclo económico. Los resultados confirman la significación de la autoeficacia, la percepción de oportunidades y el miedo al fracaso, y resaltan la importancia del conocimiento de emprendedores. Su influencia se mantiene en los distintos momentos económicos en los que se han replicado los análisis, si bien se intuyen algunas diferencias que apuntan, en etapas contractivas, a una pérdida de influencia de la confianza en las propias habilidades, frente a un incremento en el caso del juicio sobre la existencia de oportunidades en el entorno y en el caso de la presencia de emprendedores en el contexto cercano. En cambio, el comportamiento del miedo a fracasar, como barrera para emprender, se mantiene invariable en un contexto adverso respecto a uno positivo debido a la reducción de costes de oportunidad

Aps y ciudadanía comprometida: aproximación descriptiva-exploratoria a un caso.

El presente trabajo pretende analizar si la metodología de ApS contribuye al desarrollo de competencias genéricas en el alumnado universitario, especialmente con la EpD y el compromiso ético-cívico. Las técnicas cualitativas utilizadas han sido grupos de discusión, entrevistas semiestructuradas y análisis documental. Los resultados señalan que: el ApS favorece tanto el compromiso cívico como los aprendizajes curriculares de mayor complejidad, contribuyendo así al desarrollo personal y social del alumnado; la importancia de que la Universidad dé respuesta a la ciudadanía y la haga sentir cuidada y comprometida con ella; y que el profesorado mantiene una linealidad con los planteamientos anteriores

Identidad y responsabilidades socioeducativas del mediador escolar y del mediador intercultural: hacia una clarificación de funciones

El presente artículo reconoce que, ante la creciente presencia en escenarios socioeducativos de la figura profesional del mediador en los dos ámbitos principales relacionados con la educación (el escolar y el intercultural), deben identificarse los rasgos idiosincrásicos de cada uno de ellos, lo que no es óbice para reconocer cómo, a pesar de que existen, en efecto, diferencias en la definición de estos dos modelos de mediación, se evidencian aspectos coincidentes que los vinculan a un tronco común: las competencias y responsabilidades socioeducativas que adquieren cada uno de ellos. Las autoras del artículo aplican la metodología comparada para demostrar ambas realidades compatibles en las figuras del mediador escolar y el mediador intercultural, respectivamente

Networks based on QKD and weakly trusted repeaters

We study how to use quantum key distribution (QKD) in common optical network infrastructures and propose a method to overcome its distance limitations. QKD is the first technology offering information theoretic secret-key distribution that relies only on the fundamental principles of quantum physics. Point-to-point QKD devices have reached a mature industrial state; however, these devices are severely limited in distance, since signals at the quantum level (e.g. single photons) are highly affected by the losses in the communication channel and intermediate devices. To overcome this limitation, intermediate nodes (i.e. repeaters) are used. Both, quantum-regime and trusted, classical, repeaters have been proposed in the QKD literature, but only the latter can be implemented in practice. As a novelty, we propose here a new QKD network model based on the use of not fully trusted intermediate nodes, referred as weakly trusted repeaters. This approach forces the attacker to simultaneously break several paths to get access to the exchanged key, thus improving significantly the security of the network. We formalize the model using network codes and provide real scenarios that allow users to exchange secure keys over metropolitan optical networks using only passive components