Detection of dugongs from unmanned aerial vehicles

Monitoring and estimation of marine populations is of paramount importance for the conservation and management of sea species. Regular surveys are used to this purpose followed often by a manual counting process. This paper proposes an algorithm for automatic detection of dugongs from imagery taken in aerial surveys. Our algorithm exploits the fact that dugongs are rare in most images, therefore we determine regions of interest partially based on color rarity. This simple observation makes the system robust to changes in illumination. We also show that by applying the extended-maxima transform on red-ratio images, submerged dugongs with very fuzzy edges can be detected. Performance figures obtained here are promising in terms of degree of confidence in the detection of marine species, but more importantly our approach represents a significant step in automating this type of surveys.

Traffic density estimation of signalised arterials with stop line detector and probe data

This research aims to develop a reliable density estimation method for signalised arterials based on cumulative counts from upstream and downstream detectors. In order to overcome counting errors associated with urban arterials with mid-link sinks and sources, CUmulative plots and Probe Integration for Travel timE estimation (CUPRITE) is employed for density estimation. The method, by utilizing probe vehicles’ samples, reduces or cancels the counting inconsistencies when vehicles’ conservation is not satisfied within a section. The method is tested in a controlled environment, and the authors demonstrate the effectiveness of CUPRITE for density estimation in a signalised section, and discuss issues associated with the method.

Optical and biomechanical factors, associated with near work and myopia

Near work may play an important role in the development of myopia in the younger population. The prevalence of myopia has also been found to be higher in occupations that involve substantial near work tasks, for example in microscopists and textile workers. When nearwork is performed, it typically involves accommodation, convergence and downward gaze. A number of previous studies have examined the effects of accommodation and convergence on changes in the optics and biometrics of the eye in primary gaze. However, little is known about the influence of accommodation on the eye in downward gaze. This thesis is primarily concerned with investigating the changes in the eye during near work in downward gaze under natural viewing conditions. To measure wavefront aberrations in downward gaze under natural viewing conditions, we modified a commercial Shack-Hartmann wavefront sensor by adding a relay lens system to allow on-axis ocular aberration measurements in primary gaze and downward gaze, with binocular fixation. Measurements with the modified wavefront sensor in primary and downward gaze were validated against a conventional aberrometer using both a model eye and in 9 human subjects. We then conducted an experiment to investigate changes in ocular aberrations associated with accommodation in downward gaze over 10 mins in groups of both myopes (n = 14) and emmetropes (n =12) using the modified Shack-Hartmann wavefront sensor. During the distance accommodation task, small but significant changes in refractive power (myopic shift) and higher order aberrations were observed in downward gaze compared to primary gaze. Accommodation caused greater changes in higher order aberrations (in particular coma and spherical aberration) in downward gaze than primary gaze, and there was evidence that the changes in certain aberrations with accommodation over time were different in downward gaze compared to primary gaze. There were no obvious systematic differences in higher order aberrations between refractive error groups during accommodation or downward gaze for fixed pupils. However, myopes exhibited a significantly greater change in higher order aberrations (in particular spherical aberration) than emmetropes for natural pupils after 10 mins of a near task (5 D accommodation) in downward gaze. These findings indicated that ocular aberrations change from primary to downward gaze, particularly with accommodation. To understand the mechanism underlying these changes in greater detail, we then extended this work to examine the characteristics of the corneal optics, internal optics, anterior biometrics and axial length of the eye during a near task, in downward gaze, over 10 mins. Twenty young adult subjects (10 emmetropes and 10 myopes) participated in this study. To measure corneal topography and ocular biometrics in downward gaze, a rotating Scheimpflug camera and an optical biometer were inclined on a custom built, height and tilt adjustable table. We found that both corneal optics and internal optics change with downward gaze, resulting in a myopic shift (~0.10 D) in the spherical power of the eye. The changes in corneal optics appear to be due to eyelid pressure on the anterior surface of the cornea, whereas the changes in the internal optics (an increase in axial length and a decrease in anterior chamber depth) may be associated with movement of the crystalline lens, under the action of gravity, and the influence of altered biomechanical forces from the extraocular muscles on the globe with downward gaze. Changes in axial length with accommodation were significantly greater in downward gaze than primary gaze (p < 0.05), indicating an increased effect of the mechanical forces from the ciliary muscle and extraocular muscles. A subsequent study was conducted to investigate the changes in anterior biometrics, axial length and choroidal thickness in nine cardinal gaze directions under the actions of the extraocular muscles. Ocular biometry measurements were obtained from 30 young adults (10 emmetropes, 10 low myopes and 10 moderate myopes) through a rotating prism with 15° deviation, along the foveal axis, using a non-contact optical biometer in each of nine different cardinal directions of gaze, over 5 mins. There was a significant influence of gaze angle and time on axial length (both p < 0.001), with the greatest axial elongation (+18 ± 8 μm) occurring with infero-nasal gaze (p < 0.001) and a slight decrease in axial length in superior gaze (−12 ± 17 μm) compared with primary gaze (p < 0.001). There was a significant correlation between refractive error (spherical equivalent refraction) and the mean change in axial length in the infero-nasal gaze direction (Pearson's R2 = 0.71, p < 0.001). To further investigate the relative effect of gravity and extraocular muscle force on the axial length, we measured axial length in 15° and 25° downward gaze with the biometer inclined on a tilting table that allowed gaze shifts to occur with either full head turn but no eye turn (reflects the effect of gravity), or full eye turn with no head turn (reflects the effect of extraocular muscle forces). We observed a significant axial elongation in 15° and 25° downward gaze in the full eye turn condition. However, axial length did not change significantly in downward gaze over 5 mins (p > 0.05) in the full head turn condition. The elongation of the axial length in downward gaze appears to be due to the influence of the extraocular muscles, since the effect was not present when head turn was used instead of eye turn. The findings of these experiments collectively show the dynamic characteristics of the optics and biometrics of the eye in downward gaze during a near task, over time. These were small but significant differences between myopic and emmetropic eyes in both the optical and biomechanical changes associated with shifts of gaze direction. These differences between myopes and emmetropes could arise as a consequence of excessive eye growth associated with myopia. However the potentially additive effects of repeated or long lasting near work activities employing infero-nasal gaze could also act to promote elongation of the eye due to optical and/or biomechanical stimuli.

Traffic density estimation of signalised arterials with stop line detector and probe data

This research aims to develop a reliable density estimation method for signalised arterials based on cumulative counts from upstream and downstream detectors. In order to overcome counting errors associated with urban arterials with mid-link sinks and sources, CUmulative plots and Probe Integration for Travel timE estimation (CUPRITE) is employed for density estimation. The method, by utilizing probe vehicles’ samples, reduces or cancels the counting inconsistencies when vehicles’ conservation is not satisfied within a section. The method is tested in a controlled environment, and the authors demonstrate the effectiveness of CUPRITE for density estimation in a signalised section, and discuss issues associated with the method.

Through-focus performance with multifocal contact lenses : effect of binocularity, pupil diameter and inherent ocular aberrations

Purpose to evaluate the effects of the wearer’s pupil size and spherical aberration on visual performance with centre-near, aspheric multifocal contact lenses (MFCLs). The advantage of binocular over monocular vision was also investigated. Methods Twelve young volunteers, with an average age of 27±5 years, participated in the study. LogMAR Visual Acuity (VA) was measured under cycloplegia for a range of defocus levels (from +3.0 to -3.0D, in 0.5D steps) with no correction and with three aspheric MFCLs (Air Optix Aqua Multifocal, Ciba Vision, Duluth, GA, US) with a centre-near design, providing correction for “Low”, “Med” and “High” near demands. Measurements were performed for all combinations of the following conditions: i) artificial pupils of 6mm and 3mm diameter, ii) binocular and monocular (dominant eye) vision. Depth-of-focus (DOF) was calculated from the VA vs. defocus curves. Ocular aberrations under cycloplegia were measured using iTrace. Results VA at -3.0D defocus (simulating near performance) was statistically higher for the 3mm than for the 6mm pupil (p=0.006), and for binocular rather than for monocular vision (p<0.001). Similarly, DOF was better for the 3mm pupil (p=0.002) and for binocular viewing conditions (p<0.001, ANOVA). Both VA at –3.0D defocus and DOF increased as the “addition” of the MFCL correction increased. Finally, with the centre-near MFCLs a linear correlation was found between VA at –3.0D defocus and the wearer’s ocular spherical aberration (R2=0.20 p<0.001 for 6mm data), with the eyes exhibiting the higher positive spherical aberration experiencing lower VAs. By contrast, no correlation was found between VA and spherical aberration at 0.00D defocus (distance vision). Conclusions Both near VA and depth-of-focus improve with these MFCLs, with the effects being more pronounced for small pupils and binocular than for monocular vision. Coupling of the wearer’s ocular spherical aberration with the aberration profiles provided by MFCLs affects their functionality.

Prognostic significance of platelet and microvessel counts in operable non-small cell lung cancer

Background: Microvessel density, an indirect measure of angiogenesis, has been shown to be an independent prognostic marker in many solid tumours including non-small cell lung cancer (NSCLC). Platelets transport and release angiogenic growth factors. Platelets are increasingly likely to adhere to tumour microvessels due to raised expression of platelet-binding proteins and stasis in blood-flow. Increased vascular permeability in tumour microvessels facilitates platelet extravasation into the extracellular matrix. Adherence and extravasation both lead to platelet activation and release of growth factors capable of instigating the angiogenic process. Methods: A total of 181 patients were identified who underwent resection of stage I-IIIa NSCLC with a post-operative survival >60 days. Patients were followed-up for a minimum of 24 months. Sections from the tumour periphery were stained for the endothelial marker CD34 (Novocastra NCL-END) using standard ABC immunohistochemistry. Chalkley counting was used to assess microvessel density. Results: A pre-operative platelet count greater than the median and above the normal range (>400) was associated with a poor outcome (P = 0.01 and P = 0.04, respectively). Tumours with an above median and high Chalkley count (upper tertile) had a worse prognosis (P = 0.007 and P = 0.0006, respectively). There was no association between platelet count and Chalkley count. Conclusions: Platelet and microvessel counts are both potential prognostic markers for NSCLC. The role of platelets in the angiogenic process needs to be further investigated. (C) 2000 Elsevier Science Ireland Ltd.

Platelet-derived endothelial cell growth factor expression and angiogenesis in cervical intraepithelial neoplasia and squamous cell carcinoma of the cervix

Growth and metastatic spread of invasive carcinoma depends on angiogenesis, the formation of new blood vessels. Platelet-derived endothelial cell growth factor (PD-ECGF) is an angiogenic growth factor for a number of solid tumors, including lung, bladder, colorectal, and renal cell cancer. Cervical intraepithelial neoplasia (CIN) is the precursor to squamous cell cervical carcinoma (SCC). Mean vessel density (MVD) increases from normal cervical tissue, through low- and high-grade CIN to SCC. We evaluated PD-ECGF immunoreactivity and correlated its expression with MVD in normal, premalignant, and malignant cervical tissue. PD-ECGF expression was assessed visually within the epithelial tissues and scored on the extent and intensity of staining. MVD was calculated by counting the number of vessels positive for von Willebrand factor per unit area subtending normal or CIN epithelium or within tumor hotspots for SCC. Cytoplasmic and/or nuclear PD-ECGF immunoreactivity was seen in normal epithelium. PD-ECGF expression significantly increased with histologic grade from normal, through low- and high-grade CIN, to SCC (P < .02). A progressive significant increase in the microvessel density was also seen, ranging from a mean of 28 vessels for normal tissue to 57 for SCC (P < .0005). No correlation was found between PD-ECGF expression and MVD (P = .45). We conclude that PD-ECGF expression and MVD increase as the cervix transforms from a normal to a malignant phenotype. PD-ECGF is thymidine phosphorylase, a key enzyme in the activation of fluoropyrimidines, including 5-fluorouracil. Evaluation of PD-ECGF thymidine phosphorylase expression may be important in designing future chemotherapeutic trials in cervical cancer. Copyright (C) 2000 by W.B. Saunders Company.

Prognostic value of angiogenesis in operable non-small cell lung cancer

Tumour angiogenesis is an important factor for tumour growth and metastasis. Although some recent reports suggest that microvessel counts in non-small cell lung cancer are related to a poor disease outcome, the results were not conclusive and were not compared with other molecular prognostic markers. In the present study, the vascular grade was assessed in 107 (T1,2-N0,1) operable non-small cell lung carcinomas, using the JC70 monoclonal antibody to CD31. Three vascular grades were defined with appraisal by eye and by Chalkley counting: high (Chalkley score 7-12), medium (5-6), and low (2-4). There was a significant correlation between eye appraisal and Chalkley counting (P < 0.0001). Vascular grade was not related to histology, grade, proliferation index (Ki67), or EGFR or p53 expression. Tumours from younger patients had a higher grade of angiogenesis (P = 0.05). Apart from the vascular grade, none of the other factors examined was statistically related to lymph node metastasis (P < 0.0001). A univariate analysis of survival showed that vascular grade was the most significant prognostic factor (P = 0.0004), followed by N-stage (P = 0.001). In a multivariate analysis, N-stage and vascular grade were not found to be independent prognostic factors, since they were strongly related to each other. Excluding N-stage, vascular grade was the only independent prognostic factor (P = 0.007). Kaplan-Meier survival curves showed a statistically significant worse prognosis for patients with high vascular grade, but no difference was observed between low and medium vascular grade. These data suggest that angiogenesis in operable non-small cell lung cancer is a major prognostic factor for survival and, among the parameters tested, is the only factor related to cancer cell migration to lymph nodes. The integration of vascular grading in clinical trials on adjuvant chemotherapy and/or radiotherapy could substantially contribute in defining groups of operable patients who might benefit from cytotoxic treatment.

A computer image analysis system for microvessel density measurement in solid tumours

Microvessel density (MVD) is a widely used surrogate measure of angiogenesis in pathological specimens and tumour models. Measurement of MVD can be achieved by several methods. Automation of counting methods aims to increase the speed, reliability and reproducibility of these techniques. The image analysis system described here enables MVD measurement to be carried out with minimal expense in any reasonably equipped pathology department or laboratory. It is demonstrated that the system translates easily between tumour types which are suitably stained with minimal calibration. The aim of this paper is to offer this technique to a wider field of researchers in angiogenesis.

Crowd monitoring using computer vision

Novel computer vision techniques have been developed for automatic monitoring of crowed environments such as airports, railway stations and shopping malls. Using video feeds from multiple cameras, the techniques enable crowd counting, crowd flow monitoring, queue monitoring and abnormal event detection. The outcome of the research is useful for surveillance applications and for obtaining operational metrics to improve business efficiency.

Identification and elimination of a matrix-induced systematic error in LA–ICP–MS 206Pb/238U dating of zircon

Black et al. (2004) identified a systematic difference between LA–ICP–MS and TIMS measurements of 206Pb/238U in zircons, which they correlated with the incompatible trace element content of the zircon. We show that the offset between the LA–ICP–MS and TIMS measured 206Pb/238U correlates more strongly with the total radiogenic Pb than with any incompatible trace element. This suggests that the cause of the 206Pb/238U offset is related to differences in the radiation damage (alpha dose) between the reference and unknowns. We test this hypothesis in two ways. First, we show that there is a strong correlation between the difference in the LA–ICP–MS and TIMS measured 206Pb/238U and the difference in the alpha dose received by unknown and reference zircons. The LA–ICP–MS ages for the zircons we have dated can be as much as 5.1% younger than their TIMS age to 2.1% older, depending on whether the unknown or reference received the higher alpha dose. Second, we show that by annealing both reference and unknown zircons at 850 °C for 48 h in air we can eliminate the alpha-dose-induced differences in measured 206Pb/238U. This was achieved by analyzing six reference zircons a minimum of 16 times in two round robin experiments: the first consisting of unannealed zircons and the second of annealed grains. The maximum offset between the LA–ICP–MS and TIMS measured 206Pb/238U for the unannealed zircons was 2.3%, which reduced to 0.5% for the annealed grains, as predicted by within-session precision based on counting statistics. Annealing unknown zircons and references to the same state prior to analysis holds the promise of reducing the 3% external error for the measurement of 206Pb/238U of zircon by LA–ICP–MS, indicated by Klötzli et al. (2009), to better than 1%, but more analyses of annealed zircons by other laboratories are required to evaluate the true potential of the annealing method.

How much information can be obtained from tracking the position of the leading edge in a scratch assay?

Moving cell fronts are an essential feature of wound healing, development and disease. The rate at which a cell front moves is driven, in part, by the cell motility, quantified in terms of the cell diffusivity $D$, and the cell proliferation rate �$\lambda$. Scratch assays are a commonly-reported procedure used to investigate the motion of cell fronts where an initial cell monolayer is scratched and the motion of the front is monitored over a short period of time, often less than 24 hours. The simplest way of quantifying a scratch assay is to monitor the progression of the leading edge. Leading edge data is very convenient since, unlike other methods, it is nondestructive and does not require labeling, tracking or counting individual cells amongst the population. In this work we study short time leading edge data in a scratch assay using a discrete mathematical model and automated image analysis with the aim of investigating whether such data allows us to reliably identify $D$ and $\lambda$�. Using a naıve calibration approach where we simply scan the relevant region of the ($D$;$\lambda$�) parameter space, we show that there are many choices of $D$ and $\lambda$� for which our model produces indistinguishable short time leading edge data. Therefore, without due care, it is impossible to estimate $D$ and $\lambda$� from this kind of data. To address this, we present a modified approach accounting for the fact that cell motility occurs over a much shorter time scale than proliferation. Using this information we divide the duration of the experiment into two periods, and we estimate $D$ using data from the first period, while we estimate �$\lambda$ using data from the second period. We confirm the accuracy of our approach using in silico data and a new set of in vitro data, which shows that our method recovers estimates of $D$ and $\lamdba$� that are consistent with previously-reported values except that that our approach is fast, inexpensive, nondestructive and avoids the need for cell labeling and cell counting.

Letters & Numbers : a vehicle to illustrate mathematical and computing fundamentals

The television quiz program Letters and Numbers, broadcast on the SBS network, has recently become quite popular in Australia. This paper explores the potential of this game to illustrate and engage student interest in a range of fundamental concepts of computer science and mathematics. The Numbers Game in particular has a rich mathematical structure whose analysis and solution involves concepts of counting and problem size, discrete (tree) structures, language theory, recurrences, computational complexity, and even advanced memory management. This paper presents an analysis of these games and their teaching applications, and presents some initial results of use in student assignments.

A visual profile of Queensland indigenous and non-indigenous school children, and the association between vision and reading

This research investigated the prevalence of vision disorders in Queensland Indigenous primary school children, creating the first comprehensive visual profile of Indigenous children. Findings showed reduced convergence ability and reduced visual information processing skills were more common in Indigenous compared to non-Indigenous children. Reduced visual information processing skills were also associated with reduced reading outcomes in both groups of children. As early detection of visual disorders is important, the research also reviewed the delivery of screening programs across Queensland and proposed a model for improved coordination and service delivery of vision screening to Queensland school children.

Changes in ocular biometrics and refraction during near work in downward gaze over time

PURPOSE To investigate changes in the characteristics of the corneal optics, total optics, anterior biometrics and axial length of the eye during a near task, in downward gaze, over 10 min. METHODS Ten emmetropes (mean - 0.14 ± 0.24 DS) and 10 myopes (mean - 2.26 ± 1.42 DS) aged from 18 to 30 years were recruited. To measure ocular biometrics and corneal topography in downward gaze, an optical biometer (Lenstar LS900) and a rotating Scheimpflug camera (Pentacam HR) were inclined on a custom built, height and tilt adjustable table. The total optics of the eye were measured in downward gaze with binocular fixation using a modified Shack-Hartmann wavefront sensor. Initially, subjects performed a distance viewing task at primary gaze for 10 min to provide a "wash-out" period for prior visual tasks. A distance task (watching video at 6 m) in downward gaze (25°) and a near task (watching video on a portable LCD screen with 2.5 D accommodation demand) in primary gaze and 25°downward gaze were then carried out, each for 10 min in a randomized order. During measurements, in dichoptic view, a Maltese cross was fixated with the right (untested) eye and the instrument’s fixation target was fixated with the subject’s tested left eye. Immediately after (0 min), 5 and 10 min from the commencement of each trial, measurements of ocular parameters were acquired in downward gaze. RESULTS Axial length exhibited a significant increase with downward gaze and accommodation over time (p<0.05). The greatest axial elongation was observed in downward gaze with 2.5 D accommodation after 10 min (mean change from baseline 23±3 µm). Downward gaze also caused greater changes in anterior chamber depth (ACD) and lens thickness (LT) with accommodation (ACD mean change -163±12µm at 10 min; LT mean change 173±17 µm at 10 min) compared to primary gaze with accommodation (ACD mean change -138±12µm at 10 min; LT mean change 131±15 µm at 10 min). Both corneal power and total ocular power changed by a small but significant amount with downward gaze (p<0.05), resulting in a myopic shift (~0.10 D) in the spherical power of the eye compared with primary gaze. CONCLUSION The axial length, anterior biometrics and ocular refraction change significantly with accommodation in downward gaze as a function of time. These findings provide new insights into the optical and bio-mechanical changes of the eye during typical near tasks.