Performance analysis of an improved power-saving medium access protocol for IEEE 802.11 point coordination function WLAN

Wireless enabled portable devices must operate with the highest possible energy efficiency while still maintaining a minimum level and quality of service to meet the user's expectations. The authors analyse the performance of a new pointer-based medium access control protocol that was designed to significantly improve the energy efficiency of user terminals in wireless local area networks. The new protocol, pointer controlled slot allocation and resynchronisation protocol (PCSAR), is based on the existing IEEE 802.11 point coordination function (PCF) standard. PCSAR reduces energy consumption by removing the need for power saving stations to remain awake and listen to the channel. Using OPNET, simulations were performed under symmetric channel loading conditions to compare the performance of PCSAR with the infrastructure power saving mode of IEEE 802.11, PCF-PS. The simulation results demonstrate a significant improvement in energy efficiency without significant reduction in performance when using PCSAR. For a wireless network consisting of an access point and 8 stations in power saving mode, the energy saving was up to 31% while using PCSAR instead of PCF-PS, depending upon frame error rate and load. The results also show that PCSAR offers significantly reduced uplink access delay over PCF-PS while modestly improving uplink throughput.

Understanding Old Age and Victimisation: A Critical Exploration

Purpose – The purpose of paper is to shine light on the under-theorised relationship between old age and victmisation. In classical criminological studies, the relationship between “age”, victimisation and crime has been dominated by analysis of younger people's experiences. This paper aims to address this knowledge deficit by exploring older people's experiences by linking it to the social construction of vulnerability.

Design/methodology/approach – The paper explores both historical and contemporary narratives relating to the diverse experiences of older people as victims in the UK. In particular, from 1945 to the present, statistical context and theoretical advancement illuminates that older people as a social group have a deep “fear of crime” to their relative victimisation.

Findings – A careful survey of the criminological literature highlights a paucity of research relating to older people's views and experiences of crime and victimisation. The conceptual issue of vulnerability in different contexts is important in understanding ageing and victimisation in UK. The paper's findings illustrate that their experiences have remained marginalised in the debates around social policy, and how the criminal justice system responds to these changes remains yet to be seen.

Research limitations/implications – Any research attempt at theorising “age” should take into consideration not just younger people, but also the diverse experiences of older people. Policy makers may care to ponder that benchmarks be written that takes into full consideration of older people's experiences as vulnerability.

Practical implications – For criminal justice scholars and practitioners, there is a need to listen to the narratives of older people that should help shape and frame debate about their lived experiences. There should be an examination of existing formal and informal practices regarding elders, as the first step in developing an explicit and integrated set of policies and programmes to address the special needs of this group.

Originality/value – This is an original paper in highlighting how important old age is in construction of “victims” in modern society. By theorising age, victimisation and crime it is hoped to dispel and challenge some of the myths surrounding later life, crime and the older victim.

Music for Sleeping & Waking Minds

Music for Sleeping & Waking Minds is a 8-hour composition intended for overnight listening. It features 4 performers who wear custom-designed EEG sensors. The performers rest and fall asleep as they naturally would. Over the course of one night, their brainwave activity generates a spatial audio environment. Audiences are invited to sleep or listen as they wish. Composition & concept by Gascia Ouzounian. Physiological interface and interaction design by R. Benjamin Knapp. Audio interface and interaction design by Eric Lyon.

Improving the ultra-low-power performance of IEEE 802.15.6 by adaptive synchronisation

In ultra-low data rate wireless sensor networks (WSNs) waking up just to listen to a beacon every superframe can be a major waste of energy. This study introduces MedMAC, a medium access protocol for ultra-low data rate WSNs that achieves significant energy efficiency through a novel synchronisation mechanism. The new draft IEEE 802.15.6 standard for body area networks includes a sub-class of applications such as medical implantable devices and long-term micro miniature sensors with ultra-low power requirements. It will be desirable for these devices to have 10 years or more of operation between battery changes, or to have average current requirements matched to energy harvesting technology. Simulation results are presented to show that the MedMAC allows nodes to maintain synchronisation to the network while sleeping through many beacons with a significant increase in energy efficiency during periods of particularly low data transfer. Results from a comparative analysis of MedMAC and IEEE 802.15.6 MAC show that MedMAC has superior efficiency with energy savings of between 25 and 87 for the presented scenarios. © 2011 The Institution of Engineering and Technology.

USING ‘NUTRITIONAL NARRATIVE’ AND FOCUS GROUPS TO UNDERSTAND HOW NUTRITIONAL CARE CAN BETTER PRIORITISED FOR OLDER PEOPLE IN HOSPITAL SETTINGS

Introduction: Poor nutritional status among older people is well documented with 40% of older people reported as malnourished on hospital admission. Poor nutrition contributes to increased infection, poorer patient outcomes and death and longer hospital stays. In this study, we assessed the ‘nutrition narrative’ from older hospital patients together with nutrition knowledge among nursing and medical staff and students.
Methods: The study used a convenience sample of older people (30, mean age 82 years) in two large geographically separate city hospitals. Patients mentally alert and consenting, gave a recorded ‘nutrition narrative’ to get a sense of how they felt their nutritional needs were being met in hospital. Main themes were identified by grounded analysis framework. Focus groups were recruited from medical/nursing teachers and students to assess their working knowledge of nutrition and the nutritional needs of the older patient group.
Results: Analysis of the ‘nutrition narrative’ suggested several themes (i) staff should listen to patients' needs/wishes in discussion with themselves and family members (ii) staff should continue to encourage and progress a positive eating experience (iii) staff should monitor food eaten/or not eaten and increase regular monitoring of weight. The focus groups with medical and nursing students suggested a limited knowledge about nutritional care of older people and little understanding about roles or cross-talk about nutrition across the multidisciplinary groups.
Conclusions: The ‘nutrition narrative’ themes suggested that the nutritional experience of older people in hospital can and must be improved. Nursing and medical staff providing medical and nursing care need better basic knowledge of nutrition and nutritional assessment, an improved understanding of the roles of the various multidisciplinary staff and of hospital catering pathways. Care professionals need to prioritise patient nutrition much more highly and recognise nutritional care as integral to patient healing and recovery

The whole song is greater than the sum of its parts: Local and structural features in music listening

Four experiments reported here demonstrate the importance of structural as well as local features in listening to contemporary popular music. Experiment 1 established that listeners without formal musical training regard as salient the formal structure that links individual sections of songs. When asked to listen to and assemble the individual sections of unfamiliar contemporary songs to form new compositions, participants positioned the sections in ways consistent with the true structure of the music. In Experiment 2, participants were provided with only the song lyrics with which to arrange the individual sections of contemporary songs. It was found that in addition to musical features
studied in Experiment 1, lyrical content of contemporary music also acts as a strong cue to a song’s formal structure. Experiments 3 and 4 revealed that listeners’ enjoyment of music is influenced both by structural features and local features of music, which were carried by the individual song sections.
The influence of structural features on music listening was most apparent over repeated hearings. In Experiment 4, listeners’ liking for contemporary music followed an inverted U-shape trend with repeated exposure, in which liking for music took a downward turn after just four repeated hearings. In contrast, liking for restructured music increased with repeated hearings and almost eliminated an initial negative effect of restructuring by the sixth hearing. In sum, our findings demonstrate that structural features as well as local features of contemporary music are salient and important to
listeners.