Australian Communications and Media Authority

PURPOSE: The pathophysiologic basis for the [18F]fluorodeoxyglucose positron-emission tomography (FDG-PET) temporal lobe hypometabolism in patients with hippocampal sclerosis (HS) is uncertain. We tested the hypothesis that hippocampal atrophy, which is strongly correlated with hippocampal cell loss, is largely responsible for the regional hypometabolism in HS. METHODS: Regions of interest (ROIs) on FDG-PET scanning were determined in the medial, lateral, and posterior temporal lobe, thalamus, and basal ganglia. A right/left asymmetry index for each ROI was calculated. These results were correlated with hippocampal magnetic resonance imaging (MRI) volume ratios. RESULTS: There was no correlation between the magnitudes of the FDG-PET asymmetry index and the MRI volume ratio for the mesial or lateral temporal regions (r = -0.09, r = -0.04). When the right/left asymmetry index was compared with the right/left hippocampal volume ratio, correlations for the mesial temporal ROI (r = 0.79, p < 0.0001) and lateral temporal ROI (r = 0.57, p < 0.0005) were found. These, however, simply indicated that both tests accurately reflect the side of the epileptogenic region. The concordance of the side of relative hypometabolism of the FDG-PET with the side of the hippocampal atrophy was higher for the mesial temporal region (100%) than for the lateral (77.5%). CONCLUSIONS: The lack of correlation between the magnitudes of the ratios argues against hippocampal atrophy and cell loss having a central role in the FDG-PET temporal hypometabolism.

Quantitation of articular cartilage by magnetic resonance imaging and three-dimensional reconstruction has been validated and is likely to be a useful outcome measure in clinical trials of arthritis. The cost of magnetic resonance imaging is largely dependent on scanning time. The aim of this study was to compare a fast spoiled gradient-echo sequence magnetic resonance imaging scanning protocol, which takes 5 minutes and 44 seconds, with the standard, previously validated spoiled gradient-echo sequence protocol, which takes 11 minutes and 56 seconds, in the measurement of knee cartilage volume. Cartilage volumes calculated from the standard and fast magnetic resonance imaging sequences were similar. The median absolute percentage overestimation or underestimation of the cartilage volume with the fast sequence for 10 normal subjects was 2.5, 4.1, and 3.2% for patellar, femoral, and tibial cartilage, respectively. For eight subjects with osteoarthritis, the percentages were 4.3 and 3.9% for femoral and tibial cartilage, respectively. The fast spoiled gradient-echo sequence protocol had very high intra-rater and inter-rater reproducibility in normal subjects and in those with osteoarthritis. Because the cost of magnetic resonance imaging scanning is largely determined by scan time, the faster scanning protocol means that the cost of estimates of knee cartilage volume can be significantly reduced, thus increasing the feasibility of this methodology.

Caption rate and text reduction are factors that appear to affect the comprehension of captions by people who are deaf or hard of hearing. These 2 factors are confounded in everyday captioning; rate (in words per minute) is slowed by text reduction. In this study, caption rate and text reduction were manipulated independently in 2 experiments to assess any differential effects and possible benefits for comprehension by deaf and hard-of-hearing adults. Volunteers for the study included adults with a range of reading levels, self-reported hearing status, and different communication and language preferences. Results indicate that caption rate (at 130, 180, 230 words per minute) and text reduction (at 84%, 92%, and 100% original text) have different effects for different adult users, depending on hearing status, age, and reading level. In particular, reading level emerges as a dominant factor: more proficient readers show better comprehension than poor readers and are better able to benefit from caption rate and, to some extent, text reduction modifications.

Spectrum scarcity has surfaced as a prominent concern in wireless radio communications with the emergence of new technologies over the past few years. As a result, there is a growing need for better understanding of the spectrum occupancy with newly emerging access technologies supporting the Internet of Things. In this article, we present a framework to capture and model the traffic behavior of short-time spectrum occupancy for Internet-of-Things (IoT) applications in the shared bands to determine the existing interference. The proposed capturing method utilizes a software-defined radio to monitor the short bursts of IoT transmissions by capturing the time-series data which is converted to power spectral density to extract the observed occupancy. Furthermore, we propose the use of an unsupervised machine learning technique to enhance conventionally implemented energy detection methods. Our experimental results show that the temporal and frequency behavior of the spectrum can be well captured using the combination of two models, namely, semi-Markov chains and a Poisson-distribution arrival rate. We conduct an extensive measurement campaign in different urban environments and incorporate the spatial effect on the IoT shared spectrum.

Summary The germination of a population of seeds was modelled using the concept of hydrotime or hydrothermal time. Typically, a Normal distribution for base water potential ( Ψ b ( g ) ) was used within these models to relate variation in Ψ b ( g ) to the variation in time to germination of a given fraction of seeds. We sought to examine empirically the validity of this assumption, to compare the fit of alternative distributions and make recommendations for improved germination modelling procedures. Eight statistical distributions ( G umbel, W eibull, Normal, Log‐Normal, Logistic, L oglogistic, Inverse Normal and Gamma) were fitted to data for four weed species H ordeum spontaneum , P halaris minor , H eliotropium europaeum and R aphanus raphanistrum . Methods for incorporating each of these distributions into hydrotime are presented. For three species ( H . spontaneum , P . minor and H . europaeum ), the Normal distribution gave the worst fit (with AIC values: −124.2, −296.9 and −264.5, respectively) and would lead to biased predictions, whereas the L oglogistic distribution consistently provided the best explanation of Ψ b ( g ) variation in these species (with AIC values: −188.6, −326.2 and −272.1 respectively). All distributions failed to provide an unbiased description of the observed distribution of Ψ b ( g ) in R . raphanistrum . The Normal distribution is not necessarily the best function for base water potential in hydrothermal models and, indeed, may give much more biased predictions than alternative functions. The ‘best’ distribution may vary with species. The distribution of Ψ b ( g ) within a seed sample should therefore be examined and an appropriate equation selected, before using a model to make predictions.

Patients with reflex epilepsies may provide insights into cerebral pathophysiology. We report a patient with an unusual form of reflex epilepsy in whom seizures are induced by tooth brushing. Magnetic resonance imaging (MRI) demonstrated a right posterior frontal low-grade tumor predominantly involving the precentral gyrus. Video-telemetry demonstrated right-sided epileptiform activity during a typical induced complex partial seizure. An ictal single photon emission computed tomography (SPECT) scan showed an area of hyperfusion that corresponded to the MRI lesion on coregistration with a surface-matching technique. A subsequent coregistered interictal SPECT scan demonstrated hypoperfusion in the same region. Ours is the first report to demonstrate a structural focus in this unusual form of reflex epilepsy. Possible mechanisms to explain the induction of the seizures are discussed.

PURPOSE: The role of quantitative magnetic resonance imaging (MRI) in evaluation of childhood epilepsy remains poorly defined, with minimal published data. Previous work from our center questioned the specificity of hippocampal asymmetry (HA) in an outpatient group whose epilepsy was defined by using clinical and interictal data only. By using childhood volunteer controls and defining epilepsy syndromes using video-EEG monitoring, we readdressed the utility of HA in differentiating mesial temporal lobe epilepsy (MTLE) from other partial and generalized epileptic syndromes in children. METHODS: Seventy children were enrolled; entry criteria were age younger than 18 years with predominant seizure type recorded on video-EEG telemetry with volumetric MRI in all cases. Thirty healthy child volunteers had volumetric MRI. Epilepsy syndrome classification was according to ILAE. RESULTS: Control data revealed symmetric hippocampi, mean smaller/larger ratio of 0.96 (0.95-0.97, 95% CI) with no gender or right/left predominance. Overall 23% of patients had significant HA. Mean hippocampal ratio for MTLE was 0.78 (95% CI, 0.70-0.86), significantly lower than controls and from all other epilepsy syndromes. HA was highly specific (85%) to the syndrome of MTLE. Other potential epileptogenic lesions were found in 27 (39%) patients, lowest yield in frontal and mesial temporal syndromes. Dual pathology was present in 10% of patients. There was no significant association between HA and risk factors. CONCLUSIONS: In this study, we found that HA in children with a well-defined epilepsy syndrome is highly sensitive and specific for MTLE. Whether this will correlate with surgical outcome, as in adults, is the subject of ongoing study.

The through chain approach to livestock production places increased emphasis on on-farm management systems for addressing pesticide residues. The current risk management paradigm assumes the user of animal feeds has the ability to assess, or at least profile, risks to trade in animal commodities associated with feeding livestock material containing residues of pesticides. The paper details some approaches that may be used by livestock producers, focusing on simple calculations, and summarises available information needed as inputs. Calculated factors for the transfer of pesticides from feed to animal commodities (transfer factors) are summarised for about 150 pesticides.

In this paper we present the results of spectrum occupancy measurements conducted in different urban environments, in greater Melbourne area, Australia. We capture the dynamic nature of spectrum occupancy seen from a spatial perspective, by conducting spectrum monitoring measurements on board a mobile vehicle. With a wide spectrum window selected from 400 to 6000 MHz we aim to shed some light on the feasibility of utilizing smart spectrum access techniques facilitated by cognitive radios.

Internet accessibility for people with disabilities is long overdue. We draw on pioneering Australian efforts, compared with recent US and European initiatives, to argue for better disability internet policy now.

PURPOSE: In adult studies, MRI volumetrics is a proven technique in presurgical assessment of epilepsy. Hippocampal volume loss is maximal in the syndrome of mesial temporal lobe epilepsy. We aimed (a) to validate this methodology in a pediatric outpatient epilepsy population (b) to determine the relationship of hippocampal asymmetry (HA) to epileptic syndromes and risk factors. METHODS: Two neurologists classified the epileptic syndrome in 79 pediatric outpatients, according to the International Classification of Epilepsies and Epileptic Syndromes (ILAE). Hippocampal volumetrics were performed in all patients. HA was defined according to adult control values. RESULTS: Inter-rater variability on measurement of HA was very small (Correlation of test retest of 0.97 on 17 children <3 years old). The rate of HA was 44/79 (57%). In 21 patients, (27%) potentially epileptogenic lesions (other than HA) were identified (cerebral dysgenesis n = 11). HA was present in 9/15 (60%) of temporal lobe epilepsy and in 15/28 (54%) extratemporal onset epilepsy and 5/11 (46%) of generalized symptomatic epilepsy. Analysis confined to <13 years also showed HA was not specific for epileptic syndrome. There was no significant association of febrile convulsions (13%) with HA or temporal lobe epilepsy. CONCLUSIONS: There is a high incidence of HA in childhood epilepsy. HA was not confined to clinically defined temporal lobe epilepsy. The poor correlation of epileptic syndrome to quantitative MRI findings may be due to the inadequacies of epilepsy classification in the younger child, with the clinical semiology providing misleading localizing information. Normative childhood data for hippocampal volumes and symmetry is needed.

An aspect of prospect theory posits that decision‐makers, when making decisions in the face of risk, make their decisions with respect to a pre‐existing reference point or ‘frame’ (the statusquo bias). We utilize data from the Australian version of the TV game show, Deal or No Deal, to explore whether risk aversion varies with a change in reference point in a context where stakes are real and high.We achieve this by exploiting a special and unique Australian feature of the Deal or No Deal lottery‐choice setting, namely, the existence of the Chance or the SuperCase rounds (supplementary rounds). These rounds reverse the decision‐frame that was obtained in earlier (normal) rounds. We fit and estimate a complete dynamic decision‐making model to our dataset and find that the risk aversion estimate of contestants who participated in both the normal and the supplementary rounds indeed differs depending on the nature of the round, a result consistent with the operation of the existence of a framing effect.

Vast numbers of IoT devices will soon be deployed in a ubiquitous manner connecting billions of small sensors to the Internet. The means of connectivity will be primarily provided by wireless networks. This paper presents the results of a spectrum occupancy experiment conducted in the ISM-band in Melbourne, Australia. The focus of this experiment is on the spectrum window of the already highly utilized 915-928~MHz as a potential candidate for some IoT technologies. The aim of this paper is to quantify the feasibility of using this free spectrum band for present and future IoT applications. We classify the spectrum measurements according to the population densities and we formulate a relation between the current spectrum occupancy and the underlaying population density. Based on the current occupancy figures and by using the pure ALOHA access model due to its similarity to the access models currently deployed in class-licensed bands, we draw future paradigms on the available spectral room for additional IoT services in this band.

Cooperative communication techniques offer significant performance benefits over traditional methods that do not exploit the broadcast nature of wireless transmissions. Such techniques generally require advance coordination among the participating nodes to discover available neighbors and negotiate the cooperation strategy. However, the associated discovery and negotiation overheads may negate much of the cooperation benefit in mobile networks with highly dynamic or unstable topologies (e.g. vehicular networks). This paper discusses uncoordinated cooperation strategies, where each node overhearing a packet decides independently whether to retransmit it, without any coordination with the transmitter, intended receiver, or other neighbors in the vicinity. We formulate and solve the problem of finding the optimal uncoordinated retransmission probability at every location as a function of only a priori statistical information about the local environment, namely the node density and radio propagation model. We show that the solution consists of an optimal cooperation region which we provide a constructive method to compute explicitly. Our numerical evaluation demonstrates that uncoordinated cooperation offers a low-overhead viable alternative, especially in high-noise (or low-power) and high node density scenarios.

With the emergence of dynamic spectrum allocation systems, old paradigms upon which the pricing of spectrum were based no longer hold. Provided vital systems can be protected the value of spectrum is expected to become more related to the value of data it can carry and the reliability it offers. The bands which have both good available bandwidth and good propagation properties are expected to become equally valuable regardless of which technology they are currently allocated to by the national regulator. This paper explores the pricing of spectrum using only its physical attributes, taking into account ability to carry data and the cost of infrastructure needed to provide a near equivalent service. The method presented in this paper may be used as a tool when international, regional and domestic regulators make decisions on what may be the highest value use for a particular band or perhaps where prices should be set to assist a band to move to its highest value use.

There has been sustained regulatory support for the development and use of `white space' devices on UHF broadcast spectrum, particularly to provide wireless broadband services on a secondary or `unlicensed' basis. However, as regulators reallocate UHF spectrum released by the digital switchover to new services requiring a high degree of licence certainty (e.g. cellular networks) there will be incompatibilities between the rights of the new licensees and those of unlicensed white space users. What becomes of entrenched secondary usage rights if broadcast spectrum is reallocated to telecommunications and re-licensed on far more exclusive conditions than those currently prevailing for white space devices operating on a secondary basis to broadcasting services? Wide-spread deployment of white space devices could seriously complicate the reallocation of UHF band primary services from broadcasting to higher value users. This article considers Australian regulatory arrangements in light of this issue and suggests licensing reforms required to manage competing white space usage rights in the future.

Spatial diversity gained through different beamforming techniques in antenna array is one of the main advantages over the single antenna. Antenna complexity and beamwidth broadening at the scanning angles other than broadside are downsides of antenna arrays that prevent its practical implementation from some applications. In this letter, we propose an efficient beamforming method based on the sparse multiple-input-multiple-output (MIMO) array and spatial filter bank (SFB). The sparse MIMO array produces narrow beams while significantly reduces the number of array elements without compromising system performance. Multiple main beams are chosen from grating lobes by SFB. By combining sparse array geometry and SFB, we can achieve a narrower beamwidth with less antenna elements, multiple beams, and constant beamwidth. The burden of system will be transferred from the frontend hardware to the signal processing back end.

The demand for spectrum is at an all time high due to the increasing popularity of wireless devices. As such it is imperative that technological and regulatory mechanisms are developed to maximise spectral efficiency. This paper documents a method for increasing spectral efficiency through the prediction of spectrum “holes” for use with cognitive radio technologies. An algorithm is developed based upon a Hidden Markov Model of the spectral environment. The Baum-Welch algorithm is employed to dynamically calculate the transition parameters of the model. The algorithm is tested upon data collected from the 450-470 MHz band in Australia with a reward function implemented to analyse the performance of the algorithm.

We discuss the scope and nature of opportunities for white space devices to operate in the UHF band in Australia after the digital dividend. We identify opportunities for white space usage in the reduced UHF band to be used for television services as well as in nearby guard bands. We extend the discussion to the longer-term by examining scenarios in which broadcasting services could use the synergistic effects of white space devices to either voluntarily migrate out of the UHF band or secure their occupation of this important spectrum beachhead.

Fluctuations in plasma volume (PV) present potential confounders within the concentration-based markers of the haematological athlete biological passport (ABP). Here, a multi-parametric approach involving a simple blood test is applied to the current ABP adaptive model in an attempt to remove the influence of PV expansion, induced by a cycling stage race. Blood samples were obtained from 29 professional cyclists (14 male, 15 female) before, during and after 4-5 consecutive days of racing. Whole blood was analysed in accordance with the World Anti-Doping Agency ABP guidelines for haemoglobin ([Hb]) concentration and platelets. Serum and plasma were analysed for transferrin, albumin, calcium, creatinine, total protein and low-density lipoprotein. PV variation (Z-scores) was estimated using a multi-parametric model (consisting of the biomarkers mentioned earlier) and compared against calculated variations in PV (measured via CO-rebreathing). Significant reductions in [Hb] and the OFF-score were observed in female cyclists after 3 and 4 days of racing, with accompanying increases in PV, which returned to baseline values 4 days post competition. Similarly, a significant increase in PV was observed in male cyclists after 3 and 5 days of racing. When individual estimations of PV variance were applied to the adaptive model, the upper and lower reference predictions for [Hb] and the OFF-score were refined such that all outliers consistent with racing-induced PV changes were removed. The PV model appears capable of reducing the influence of PV on concentration-dependent markers during competition. This is an important step towards the inclusion of the PV correction in the ABP haematological module.