We tested the hypothesis that the phototatic response of nocturnal insects is influenced by the flickering of light sources by comparing the numbers of insects captured in traps illuminated with flickering and non-flickering light. Four flicker profiles produced by a square pulse wave with different combinations of frequency and duty cycle were investigated. Overall, fewer insects were captured in traps illuminated with a flickering light source, independent of the flicker setting used. Furthermore, the difference observed was statistically significant for specific combinations of flickering conditions and insect orders, thus suggesting that flickering reduces the number of nocturnal insects attracted to light sources.

Artificial lighting allows humans to be active at night, but has many unintended consequences, including interference with ecological processes, disruption of circadian rhythms and increased exposure to insect vectors of diseases. Although ultraviolet and blue light are usually most attractive to arthropods, degree of attraction varies among orders. With a focus on future indoor lighting applications, we manipulated the spectrum of white lamps to investigate the influence of spectral composition on number of arthropods attracted. We compared numbers of arthropods captured at three customizable light-emitting diode (LED) lamps (3510, 2704 and 2728 K), two commercial LED lamps (2700 K), two commercial compact fluorescent lamps (CFLs; 2700 K) and a control. We configured the three custom LEDs to minimize invertebrate attraction based on published attraction curves for honeybees and moths. Lamps were placed with pan traps at an urban and two rural study sites in Los Angeles, California. For all invertebrate orders combined, our custom LED configurations were less attractive than the commercial LED lamps or CFLs of similar colour temperatures. Thus, adjusting spectral composition of white light to minimize attracting nocturnal arthropods is feasible; not all lights with the same colour temperature are equally attractive to arthropods.

There are currently no accepted metrics for summarising lighting conditions in studies aimed at investigating effects mediated by the circadian system. The objectives of this paper are to propose a set of metrics for capturing circadian variations in environmental lighting conditions and to compare two different lighting regimes applied to patient rooms. Our metric design emphasises the characterisation of light stimuli over time, e.g. their spread over one or more days. Lighting measurements for comparative assessment were taken in 20 beds in the intensive care unit of the Jeroen Bosch Hospital. Lighting conditions between the intensive care unit beds differed significantly across a number of circadian metrics. The proposed set of metrics offers a simple yet comprehensive approach to characterising lighting conditions from the circadian perspective with direct application in clinical studies investigating the effects of light on health.

Many species of insects display a disposition to move towards light. As a consequence, nocturnal artificial lighting often contributes to an increase in insect population among humans. We tested the hypothesis that residential white lamps can evoke significantly different attraction to insects even when their light outputs are nearly indistinguishable to humans. In a two-choice experiment using insect traps equipped with either a compact fluorescent or a LED light source with similar photometric specifications, about three times more insects were captured in the trap with a compact fluorescent lamp than in the LED trap. The results suggest that LED lamps are preferable to compact fluorescent lamps when the objective is to avoid attracting nocturnal insects to households.

We describe a model-based strategy for defining an optimal lighting schedule for strengthening the circadian rhythms of patients in intensive care units as a means of reducing delirium rates in hospitals. The effect of different lighting schedules on the amplitude of the circadian rhythms was assessed via computer simulations using a model of the circadian system. The simulation results show a large boost of the amplitude of circadian rhythms when the photoperiod is within the 6 h–16 h duration range at relatively modest light levels. It is concluded that a fast recovery of endogenous circadian rhythm can be supported by daily light pulses of about 6 h without necessarily causing visual discomfort to subjects.

Radar is an attractive technology for long term monitoring of human movement as it operates remotely, can be placed behind walls and is able to monitor a large area depending on its operating parameters. A radar signal reflected off a moving person carries rich information on his or her activity pattern in the form of a set of Doppler frequency signatures produced by the specific combination of limbs and torso movements. To enable classification and efficient storage and transmission of movement data, unique parameters have to be extracted from the Doppler signatures. Two of the most important human movement parameters for activity identification and classification are the velocity profile and the fundamental cadence frequency of the movement pattern. However, the complicated pattern of limbs and torso movement worsened by multipath propagation in indoor environment poses a challenge for the extraction of these human movement parameters. In this paper, three new approaches for the estimation of human walking velocity profile in indoor environment are proposed and discussed. The first two methods are based on spectrogram estimates whereas the third method is based on phase difference computation. In addition, a method to estimate the fundamental cadence frequency of the gait is suggested and discussed. The accuracy of the methods are evaluated and compared in an indoor experiment using a flexible and low-cost software defined radar platform. The results obtained indicate that the velocity estimation methods are able to estimate the velocity profile of the person’s translational motion with an error of less than 10%. The results also showed that the fundamental cadence is estimated with an error of 7%.

Radar is an attractive technology for long term monitoring of human movement as it operates remotely, can be placed behind walls and is able to monitor a large area depending on its operating parameters. A radar signal reflected off a moving person carries rich information on his or her activity pattern in the form of a set of Doppler frequency components produced by the specific combination of limbs and torso movements. Deploying radars in indoor environments poses however challenges for the interpretation of signals reflected off a moving object due to multipath propagation. Two strategies for the estimation of human walking velocity profile in indoor environments are suggested and discussed. The accuracy of the strategies are evaluated and compared in a field experiment using a flexible and low-cost software defined radar platform. The results obtained indicate that both methods are able to estimate the velocity profile of the person's translational movement with less than 10% error.

Human activity quantification consists of computing a numerical or qualitative metric that indicates the amount of movement a person engaged in a given time interval. Such a metric has important applications in elderly care, wellness and healthcare given the strong empirical relation between a person’s health and his or her activity level. This paper proposes and evaluates methods to quantify the level of human activity in an indoor environment using a continuous wave radar. An experimental evaluation is carried out using a flexible and low-cost software defined radar platform. Results showed a good correlation between the proposed metrics and the motion sequence performed by the subject suggesting that accurate activity quantification in indoor environments can be achieved using a few simple off-body sensors.

This article presents a framework and methodology to create personal health record (PHR) systems able to transform raw health data into meaningful information for the general population. By bridging the semantic gap between an individual and his or her health data, it is expected that better care will ensue through consumer empowerment. An important challenge for the realization of this vision is the lack of available expert knowledge in a format that is concomitantly easy to codify, share, and be used by the general population. To address this challenge, we developed a novel approach to encode expert knowledge into machine-interpretable, reusable components called "consumer guidelines." Once encoded, guidelines are easily shared, extended, and modified. These guidelines can exist as distributed documents on the Internet and be executed by our processing engine (Health-Guru) to provide an individual with personalized assessment against various health risks based on the evidence data stored in a PHR.

The FP6 project “Wireless Accessible Sensor Populations” (WASP) has developed an end-to-end infrastructure for the deployment and enterprise integration of wireless sensor nodes. The infrastructure is generic and allows for optimisation for a variety of applications by the development of dedicated services that can be distributed over (wearable and ambient) sensor nodes, the WSN gateway, and the enterprise (backend) system. Key to many applications, such as elderly care considered in this paper, is to optimise the battery lifetime of wearable sensor nodes that can be (remotely) customized to the monitoring needs of individual persons and to the quality-of-service demands for offered services. The WASP infrastructure provides practical solutions for these targets and is being validated for realistic elderly care scenarios. These scenario's aim to support the elderly in (semi-) independent Ambient Assisted Living settings as well as to provide health workers with effective means of studying transient deterioration and behavior changes characteristic to the ageing population.

The current medium access control (MAC) protocol of the wireless access in vehicular environments (WAVE) system is based on IEEE 802.11 distributed coordination function (DCF) and enhanced distributed channel access (EDCA), which have drawbacks in supporting throughput-sensitive non-safety applications in vehicular ad-hoc network (VANET). In order to address the problem, we propose a novel MAC protocol, namely vehicular MESH network (VMESH), which is specifically designed for the control channel (CCH) and multiple service channels (SCHs) structure of WAVE. A synchronized and distributed beaconing scheme is employed in the VMESH protocol for the purposes of neighborhood awareness and dynamic resource reservation on SCHs. The advantages of the VMESH protocol in supporting the throughput-sensitive non-safety applications in VANET are shown through the theoretical analysis comparing to the current WAVE MAC.

The current medium access control (MAC) protocol of the wireless access in vehicular environments (WAVE) system is based on IEEE 802.11 distributed coordination function (DCF) and enhanced distributed channel access (EDCA), which have drawbacks in supporting throughput-sensitive applications in high density networks, e.g. future vehicular ad-hoc networks (VANET). In order to address the problem, we propose a novel MAC protocol, namely vehicular MESH network (VMESH), which is specifically designed for the control channel (CCH) and multiple service channels (SCHs) architecture of WAVE system. A synchronized and distributed beaconing scheme is employed by the VMESH protocol for the purposes of neighborhood awareness and dynamic channel resource reservation. In this paper, we present the advantage of VMESH protocol under saturated traffic load condition through theoretical analysis. For more realistic scenarios with mobility and unsaturated traffic loads, through the simulative study, we can also show that the VMESH protocol outperforms the WAVE protocol when the traffic load is heavy.

Denial of Service (DoS) attacks impose an increasingly growing threat to the Internet. These attacks result in wastage of scarce Internet resources and service disruptions. Existing packet filtering schemes are deployable at either source, intermediate or victim networks. In this paper, we propose a hybrid of the source and the victim networks-based packet filtering approach, Source Router marking and Hop-Count (SRHC), to detect and filter high-rate traffic flows and IP-spoofing attacks. Packets are marked at the source network based on their arrival rate threshold. At a victim network, the spoofed packets are marked based on the IP source arrival rate using their respective TTL value. Both source and victim networks collaborate to filter high-rate and IP-spoofing attacks. The ns-2 simulator is used to generate attack scenarios. Our simulation results show that the SRHC scheme effectively filters out high-rate and IP-spoofing attack packets, with minimal collateral damage.

The task scheduling problem consists in defining a time sharing of system resources that can meet all l ogical and temporal constraints of the tasks being considered. In real-time distributed systems such a problem can be broken up in two related steps: task allocation and local task scheduling. Task allocation can be performed dynamically or statically. For tasks with predictable behavior (periodic or sporadic), static scheduling provides a reliable way to meet time constraints. This is of fundamental importance when defining an allocation for hard-deadline tasks. Unfortunately, finding an optimal feasible allocation is known to be NP-hard. Therefore, heuristic approaches for finding good allocations in polynomial time have been studied. In this paper we describe the use of a new heuristic to generate static schedules for criti cal periodic tasks in real-time distributed systems. In order to evaluate the benefits of the proposed approach, termed microcanonical optimization, a study is performed to compare the quali ty of the achieved schedules with the ones obtained with alternative heuristics, namely, simulated annealing, tabu search and Tsalli s’s annealing. Our experiments show that microcanonical optimization is able to outperform the competing heuristics, achieving better allocations in shorter processing times.

The movement of nodes in mobile ad hoc networks can be inferred by inspecting unique addresses embedded into exchanged messages. If these addresses are fixed, tracing a message to a single source is trivial and movement can be easily uncovered by listening to transmissions in the area of interest. The ease in which such traces can be obtained creates a fertile environment for information misuse and privacy violation. In this paper, a scheme based on address randomization is proposed to reduce traceability in mobile ad hoc networks. The novel feature of the scheme consists of producing new addresses without disrupting communication that relies on keeping neighbor state. This feature is obtained by randomizing addresses progressively, bit by bit, until the desired uncorrelation between old and new address is obtained.

Nodes in a wireless network transmit messages through a shared medium. Thus, a Media Access Control (MAC) protocol is necessary to regulate and coordinate medium access. For some application areas it is necessary to have a deterministic MAC protocol which can give guarantees on message delay and channel throughput. Schedule based MAC protocols, based on time synchronization among nodes, are currently used to implement deterministic MAC protocols. Time synchronization is difficult and costly, especially in energy constrained sensor networks. In this paper the f-MAC protocol is presented which can give guarantees regarding message delay and channel throughput without the requirement of time synchronization among nodes. The various trade-offs of f-MAC are analysed and discussed and application areas that would benefit from f-MAC are presented.