Spatial scales of interactions among bacteria and between bacteria and the leaf surface.

Microbial life on plant leaves is characterized by a multitude of interactions between leaf colonizers and their environment. While the existence of many of these interactions has been confirmed, their spatial scale or reach often remained unknown. In this study, we applied spatial point pattern analysis to 244 distribution patterns of Pantoea agglomerans and Pseudomonas syringae on bean leaves. The results showed that bacterial colonizers of leaves interact with their environment at different spatial scales. Interactions among bacteria were often confined to small spatial scales up to 5-20 μm, compared to interactions between bacteria and leaf surface structures such as trichomes which could be observed in excess of 100 μm. Spatial point-pattern analyses prove a comprehensive tool to determine the different spatial scales of bacterial interactions on plant leaves and will help microbiologists to better understand the interplay between these interactions

Impact assessment to measure the success of implementation of rural community engagement projects. a case study

Abstract: This paper describes how the use of an impact assessment reveals unknown information to project teams who conduct community engagement engineering projects in rural and distant villages. The paper depicts a “tried and tested” case study to describe how the impact assessment is done and the information revealed. The second phase of the Gwakwani project included the installation of off-grid solar home systems in the community. An assessment was later done which measured the impact of the technology in the area, using survey analysis

Toward inductive learning of energy-related concepts

Abstract: Energy is an important topic in science and engineering. Yet, clear definitions of this concept are difficult to come by and, as a result, students often develop a limited understanding of energy and energy-related concepts. This is exacerbated by traditional, deductive means of teaching. In this paper, the authors report on an attempt at introducing an inductive approach to the teaching and learning of energy-related concepts, specifically conservation of energy. The approach was attempted among a select group of school students using inductive means, and was adapted from an article in the literature that addressed flight energy management training for pilots. The aim of the paper is to describe the intervention, which sought to foster a deeper understanding of energy flows within a system and place the school students in good stead for their subsequent design of an ultra-energy efficient hydrogen-powered vehicle. This is done in order to demonstrate how inductive learning can be enacted in an engineering curriculum. However, the intervention was implemented with a small sample of students and, as such, further attention needs to be given to how such an inductive learning approach can be incorporated into formal curricula at both school and university levels, with a diverse range of students, and with diverse topics

Cellular technology for prevention of “Give and forget” community service projects

Abstract: This paper describes the use of cellular network technology to monitor installed equipment performance in a rural village as part of a community service project. Monitoring of the equipment enables early detection of performance deviations enabling cost effective preventative maintenance avoiding “give and forget” rural projects. Results are presented for performance data collected at a remote rural village solar installation and communicated through a data radio and the cellular network to a control station in an educational environment

Contribution of noise to the variance of integrating detectors

X-ray medical imaging provides invaluable medical information, while subjecting patients to hazardous ionizing radiation. The dosage that the patient is exposed to may be reduced, at the cost of image resolution. A technology that promises lower dosage for a given resolution is direct conversion digital imaging, typically based on amorphous Selenium semiconductor. Sufficient exposure should be used for the first exposure to avoid subsequent exposures; a challenge is then to reduce the necessary exposure for a suitable image. To quantify how little radiation the detector can reliably discriminate, one needs an analysis of the variance that 1/f and white noise contribute to the signal of such detectors. An important consideration is that the dark current, which varies with time, is subtracted from the photo-current, to reduce the spurious spatial variance in the image. In this thesis, the variance that 1/f noise contributes to integrating detectors is analysed, for a very general integrating detector. Experiments were performed to verify the theoretical results obtained for the 1/f noise variance contribution

Urinary chitinase 3-like protein 1 for early diagnosis of acute kidney injury : a prospective cohort study in adult critically ill patients

Background: Acute kidney injury (AKI) occurs frequently and adversely affects patient and kidney outcomes, especially when its severity increases from stage 1 to stages 2 or 3. Early interventions may counteract such deterioration, but this requires early detection. Our aim was to evaluate whether the novel renal damage biomarker urinary chitinase 3-like protein 1 (UCHI3L1) can detect AKI stage >= 2 more early than serum creatinine and urine output, using the respective Kidney Disease vertical bar Improving Global Outcomes (KDIGO) criteria for definition and classification of AKI, and compare this to urinary neutrophil gelatinase-associated lipocalin (UNGAL). Methods: This was a translational single-center, prospective cohort study at the 22-bed surgical and 14-bed medical intensive care units (ICU) of Ghent University Hospital. We enrolled 181 severely ill adult patients who did not yet have AKI stage >= 2 based on the KDIGO criteria at time of enrollment. The concentration of creatinine (serum, urine) and CHI3L1 (serum, urine) was measured at least daily, and urine output hourly, in the period from enrollment till ICU discharge with a maximum of 7 ICU-days. The concentration of UNGAL was measured at enrollment. The primary endpoint was the development of AKI stage >= 2 within 12 h after enrollment. Results: After enrollment, 21 (12 %) patients developed AKI stage >= 2 within the next 7 days, with 6 (3 %) of them reaching this condition within the first 12 h. The enrollment concentration of UCHI3L1 predicted the occurrence of AKI stage >= 2 within the next 12 h with a good AUC-ROC of 0.792 (95 % CI: 0.726-0.849). This performance was similar to that of UNGAL (AUC-ROC of 0.748 (95 % CI: 0.678-0.810)). Also, the samples collected in the 24-h time frame preceding diagnosis of the 1st episode of AKI stage >= 2 had a 2.0 times higher (95 % CI: 1.3-3.1) estimated marginal mean of UCHI3L1 than controls. We further found that increasing UCHI3L1 concentrations were associated with increasing AKI severity. Conclusions: In this pilot study we found that UCHI3L1 was a good biomarker for prediction of AKI stage >= 2 in adult ICU patients

A critique on previous work in vision aided navigation

This paper presents a critique on previous work in the field of vision aided navigation, particularly in the fusion of visual and inertial sensors for navigation. Several improvements and updates are proposed for the existent systems. GPS receivers have allowed for accurate navigation for many vehicles and robotic platforms. GPS based navigation can, however, prove to be impractical in applications where there is no GPS reception such as underground, indoors or in some urban areas. This pertains, in particular, to many robotic applications where position must be known in global coordinates or relative to a reference point. An inertial navigation system (INS) can be used to calculate one’s relative navigation state via dead-reckoning calculations. The downfall of a low-cost INS is the errors associated with the system. While these errors are initially small, integration causes large drift errors over time. To combat this problem, cameras can be used to estimate the errors present in the INS readings. These results can then be used to correct the navigation state output from the INS. While the motion estimations from the cameras are not error-free, this method is made highly effective because of the complementary nature of the errors from the cameras and INS. Several improvements are proposed for this method; algorithmically, in updates to its hardware, and with the introduction of graphics processors to improve computational performance. The overall system performance, individual steps, algorithms, and results are compared to results from similar works to those of the proposed improvements. It is shown that the accuracy, responsiveness and overall performance of the system can potentially be greatly improved

A Cayley-Hamilton trace identity for 2 x 2 matrices over Lie-solvable rings

We exhibit a Cayley-Hamilton trace identity for $2\times2$ matrices with entries in a ring $R$ satisfying $[[x,y],[x,z]]=0$ and 1/2 \in R$