The ones that come ready made:The identification and use of Sus tusks as tools at prehistoric cave sites in Malaysia

Evidence for osseous technologies has featured in excavation reports from Southeast Asia for almost a century and from archaeological deposits as old as 43,000 years BP. However, in contrast to the significance that is placed on this technology in other parts of the world, until recently, Southeast Asian assemblages have drawn only very limited attention. Concentrating on evidence from Malaysia, the current paper examines one element of this inventory of tools: the deliberate modification of pig canines and the means by which such alteration can be distinguished from patterns of natural tooth wear. Particular attention is paid to the bearded pig (Sus barbatus), as it is one of the two species of wild boar in Malaysia whose tusks are most likely to have been used by prehistoric toolmakers. Reference is also made to wider, regional ethnographic examples of known tusk implements and their accredited uses to further assist in the identification process. Distinguishing criteria for worked tusk are formulated according to the type and extent of modification. These criteria are then applied to archaeological specimens recovered from two prehistoric cave sites in Malaysia, Gua Bintong and Niah Cave.

Practical Spectrum Aggregation for Secondary Networks with Imperfect Sensing

We investigate a collision-sensitive secondary network that intends to opportunistically aggregate and utilize spectrum of a primary network to achieve higher data rates. In opportunistic spectrum access with imperfect sensing of idle primary spectrum, secondary transmission can collide with primary transmission. When the secondary network aggregates more channels in the presence of the imperfect sensing, collisions could occur more often, limiting the performance obtained by spectrum aggregation. In this context, we aim to address a fundamental query, that is, how much spectrum aggregation is worthy with imperfect sensing. For collision occurrence, we focus on two different types of collision: one is imposed by asynchronous transmission; and the other by imperfect spectrum sensing. The collision probability expression has been derived in closed-form with various secondary network parameters: primary traffic load, secondary user transmission parameters, spectrum sensing errors, and the number of aggregated sub-channels. In addition, the impact of spectrum aggregation on data rate is analysed under the constraint of collision probability. Then, we solve an optimal spectrum aggregation problem and propose the dynamic spectrum aggregation approach to increase the data rate subject to practical collision constraints. Our simulation results show clearly that the proposed approach outperforms the benchmark that passively aggregates sub-channels with lack of collision awareness.

The Local and the Distributed in the Sonic Arts

This paper addresses the relationship between local and distributed strategies with reference to two recent participatory sound art projects in Belfast and Rio de Janeiro. The local concern for site and place is discussed and juxtaposed with distributed practices, which,by definition question and extend the very notion of site or locale. I refer to examples from ethnomusicology, anthropology and education in which participative horizontal research methodologies lead to a dynamic articulation of local conditions and allow for a reflection on how technology impacts on social interaction and relationships with place. The works of Samuel Araújo, Georgina Born and Brazilian pedagogue Paulo Freire provide a framework of reference in this context.

Dual-Hop Cognitive Amplify-and-Forward Relaying Networks over η− μ Fading Channels

This paper presents a thorough performance analysis of dual-hop cognitive amplify-and-forward (AF) relaying networks under spectrum-sharing mechanism over independent non-identically distributed (i.n.i.d.) 􀀀 fading channels. In order to guarantee the quality-of-service (QoS) of primary networks, both maximum tolerable peak interference power Q at the primary users (PUs) and maximum allowable transmit power P at secondary users (SUs) are considered to constrain transmit power at the cognitive transmitters. For integer-valued fading parameters, a closed-form lower bound for the outage probability (OP) of the considered networks is obtained. Moreover, assuming arbitrary-valued fading parameters, the lower bound in integral form for the OP is derived. In order to obtain further insights on the OP performance, asymptotic expressions for the OP at high SNRs are derived, from which the diversity/coding gains and the diversity-multiplexing gain tradeoff (DMT) of the secondary network can be readily deduced. It is shown that the diversity gain and also the DMT are solely determined by the fading parameters of the secondary network whereas the primary network only affects the coding gain. The derived results include several others available in previously published works as special cases, such as those for Nakagami-m fading channels. In addition, performance evaluation results have been obtained by Monte Carlo computer simulations which have verified the accuracy of the theoretical analysis.

Cell Coverage Optimization for the Multicell Massive MIMO Uplink

We investigate the cell coverage optimization problem for the massive multiple-input multiple-output (MIMO) uplink. By deploying tilt-adjustable antenna arrays at the base stations, cell coverage optimization can become a promising technique which is able to strike a compromise between covering cell-edge users and pilot contamination suppression. We formulate a detailed description of this optimization problem by maximizing the cell throughput, which is shown to be mainly determined by the user distribution within several key geometrical regions. Then, the formulated problem is applied to different example scenarios: for a network with hexagonal shaped cells and uniformly distributed users, we derive an analytical lower bound of the ergodic throughput in the objective cell, based on which, it is shown that the optimal choice for the cell coverage should ensure that the coverage of different cells does not overlap; for a more generic network with sectoral shaped cells and non-uniformly distributed users, we propose an analytical approximation of the ergodic throughput. After that, a practical coverage optimization algorithm is proposed, where the optimal solution can be easily obtained through a simple one-dimensional line searching within a confined searching region. Our numerical results show that the proposed coverage optimization method is able to greatly increase the system throughput in macrocells for the massive MIMO uplink transmission, compared with the traditional schemes where the cell coverage is fixed.

Wearable antennas for medical monitoring systems

A wearable silver nano particle inkjet printed antenna suitable for wireless biomedical sensing is presented. The performance is evaluated on a synthetic variable layered phantom test-bed, representative of human tissue for operation in the 868/915 MHz, and 2400 MHz industrial, scientific and medical frequency bands. Antenna radiation efficiency measurements on the phantom were compared with antennas prototyped with copper. Total radiation efficiencies up to ???6.5 dB are reported, with less than 0.5 dB difference in performance between copper and silver nano particle variants, showing promising application for low-cost disposable wireless sensing.

FPGA based Streaming Image Processing Processor (SIPPro) architecture to accelerate data intensive applications

Current data-intensive image processing applications push traditional embedded architectures to their limits. FPGA based hardware acceleration is a potential solution but the programmability gap and time consuming HDL design flow is significant. The proposed research approach to develop “FPGA based programmable hardware acceleration platform” that uses, large number of Streaming Image processing Processors (SIPPro) potentially addresses these issues. SIPPro is pipelined in-order soft-core processor architecture with specific optimisations for image processing applications. Each SIPPro core uses 1 DSP48, 2 Block RAMs and 370 slice-registers, making the processor as compact as possible whilst maintaining flexibility and programmability. It is area efficient, scalable and high performance softcore architecture capable of delivering 530 MIPS per core using Xilinx Zynq SoC (ZC7Z020-3). To evaluate the feasibility of the proposed architecture, a Traffic Sign Recognition (TSR) algorithm has been prototyped on a Zedboard with the color and morphology operations accelerated using multiple SIPPros. Simulation and experimental results demonstrate that the processing platform is able to achieve a speedup of 15 and 33 times for color filtering and morphology operations respectively, with a significant reduced design effort and time.

Second-Order Statistics of κ−µ Shadowed Fading Channels

In this paper, novel closed-form expressions for the level crossing rate and average fade duration of κ − μ shadowed fading channels are derived. The new equations provide the capability of modeling the correlation between the time derivative of the shadowed dominant and multipath components of the κ − μ shadowed fading envelope. Verification of the new equations is performed by reduction to a number of known special cases. It is shown that as the shadowing of the resultant dominant component decreases, the signal crosses lower threshold levels at a reduced rate. Furthermore, the impact of increasing correlation between the slope of the shadowed dominant and multipath components similarly acts to reduce crossings at lower signal levels. The new expressions for the second-order statistics are also compared with field measurements obtained for cellular device-to-device and body-centric communication channels, which are known to be susceptible to shadowed fading.

Energy Detection based Spectrum Sensing over Two-wave with Diffuse Power Fading Channels

One of the most important factors that affects the performance of energy detection (ED) is the fading channel between the wireless nodes. This article investigates the performance of ED-based spectrum sensing, for cognitive radio (CR), over two-wave with diffuse power (TWDP) fading channels. The TWDP fading model characterizes a variety of fading channels, including well-known canonical fading distributions, such as Rayleigh and Rician, as well as worse than Rayleigh fading conditions modeled by the two-ray fading model. Novel analytic expressions for the average probability of detection over TWDP fading that account for single-user and cooperative spectrum sensing as well as square law selection diversity reception are derived. These expressions are used to analyze the behavior of ED-based spectrum sensing over moderate, severe and extreme fading conditions, and to investigate the use of cooperation and diversity as a means of mitigating the fading effects. Our results indicate that TWDP fading conditions can significantly degrade the sensing performance; however, it is shown that detection performance can be improved when cooperation and diversity are employed. The presented outcomes enable us to identify the limits of ED-based spectrum sensing and quantify the trade-offs between detection performance and energy efficiency for cognitive radio systems deployed within confined environments such as in-vehicular wireless networks.

Design of an OFDM Physical Layer Encryption Scheme

This paper presents a new encryption scheme implemented at the physical layer of wireless networks employing orthogonal frequency-division multiplexing (OFDM). The new scheme obfuscates the subcarriers by randomly reserving several subcarriers for dummy data and resequences the training symbol by a new secure sequence. Subcarrier obfuscation renders the OFDM transmission more secure and random, while training symbol resequencing protects the entire physical layer packet, but does not affect the normal functions of synchronization and channel estimation of legitimate users while preventing eavesdroppers from performing these functions. The security analysis shows the system is robust to various attacks by analyzing the search space using an exhaustive key search. Our scheme is shown to have a better performance in terms of search space, key rate and complexity in comparison with other OFDM physical layer encryption schemes. The scheme offers options for users to customize the security level and key rate according to the hardware resource. Its low complexity nature also makes the scheme suitable for resource limited devices. Details of practical design considerations are highlighted by applying the approach to an IEEE 802.11 OFDM system case study.

Concepções e práticas CTS dos professores de uma escola inovadora

Numa sociedade cada vez mais permeada pelo desenvolvimento científicotecnológico emerge o reconhecimento da importância da Educação em Ciência, Tecnologia e Sociedade (CTS). Neste sentido, investigações estão a ser produzidas sobre a relação existente entre as concepções dos professores sobre CTS e suas práticas de ensino, mas os resultados são controversos. Assim, o presente estudo procurou contribuir para compreensão da relação entre as concepções sobre CTS e as práticas didáctico-pedagógicas desenvolvidas por professores de uma escola portuguesa considerada inovadora. Através de um estudo de caso, de natureza qualitativa, a investigação envolveu dois professores que trabalham com alunos do 3º ao 6º ano de escolaridade e utilizou diversas técnicas e instrumentos de recolha de dados. As concepções sobre CTS foram levantadas com a aplicação do questionário VOSTS “Views on Science-Technology-Society” (versão portuguesa adaptada por Canavarro, 2000). As práticas didáctico-pedagógicas dos professores caracterizaram-se com o apoio do “Instrumento de Caracterização das Práticas Pedagógico-Didácticas CTS” (Vieira, 2003) e do registo das observações das aulas dos professores através do Diário do Investigador e de áudio-gravações. O processo de análise dos dados aponta para concepções ingénuas sobre CTS dos professores, onde a Ciência e a Tecnologia foi vista como, por exemplo, “domínios interligados que nem sempre repercutem na sociedade”. Relativamente às práticas didáctico-pedagógicas, evidencia-se um ensino que valoriza o conhecimento e, embora inserido num contexto sócio-construtivista de Escola, este não contempla explicitamente uma orientação CTS. Sobre a relação entre as concepções sobre CTS dos professores e suas práticas didáctico-pedagógicas implementadas no ensino de Ciências, os resultados obtidos não permitem estabelecer conclusivamente uma relação ou a ausência dela. Contudo, os resultados trazem contributos, ainda que modestos, para a compreensão desta questão e salientam a complexidade da problemática abordada. Quanto ao contexto escolar inovador em que se realizou a investigação, os resultados apontam algumas divergências entre a proposta teórica do projecto pedagógico e as práticas implementadas em sala de aula. Portanto, uma proposta pedagógica que apresenta potenciais para um ensino com orientação CTS não se consolida se os professores não forem preparados para explorar este potencial. Salienta-se, assim, a necessidade de formação inicial e continuada de professores no Ensino das Ciências com Orientação CTS. ABSTRACT: In one society more and more promoted by scientific and technological development emerges the recognition of the importance of the Science, Society, and Technology (STS) in our Education. In these sense, investigations are being follow up about the existing relation between the conceptions of the teachers about STS and their practices in education, but the results are controversial. Thus, the present study it looked forward to contribute for the knowledge of relations between the conceptions of STS and their didacticpedagogical issues developed by teachers of one portuguese school considered innovative. Through a study of a case, of qualitative nature, an investigation involving two teachers which work with students of the third and sixth year of scholarship and using a broad of diverse techniques and instruments of data acquire. Conceptions about STS where taken in account with the use a questionnaire VOSTS " Views on Science-Technology-Society " (Portuguese version adapted by Canavarro, 2000). The didactic-pedagogical practices used by teachers are characterized by the support of " Instruments of characterization of didacticpedagogical practices STS" (Vieira, 2003) and of the registry of class observations by the teachers through the Investigator Diary as well as audio recordings. The process of analysis of data acquire leads to ingénues conceptions about the STS of the teachers, where Science and Technology was seen as, for example, "inter ligated domains which not always have repercussions in society". Relatively to didactic-pedagogical issues, it is proven that one education that embraces knowledge but insert in a context of socialconstructiveness of School will not contemplate an explicit orientation towards STS. About relation between the conceptions related to STS used by the teachers and their didactic-pedagogical issues implemented in education of Science, the results do not allow to establish a conclusive connection them or the lack of it. However, the results bring modest contributes for the comprehension of these question and they point out the complexity of the topic taken in account. To sum up, in relation to the innovative school context in which the investigation was taken the results lead to some divergences between the theoretical proposal of the pedagogic project and the practices implemented in the school class. So, one pedagogical proposal, which shows potential positive issues for one education STS oriented, does not get consolidated if the teachers are not prepared to explore this issue. It is lined out, the necessity of initial formation and trough life by the teachers in Education of Sciences with orientation to STS.