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"Steele, Jonathan"
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γ-Heptalactone is an endogenously produced quorum-sensing molecule regulating growth and secondary metabolite production by Aspergillus nidulans
Microbes monitor their population density through a mechanism termed quorum sensing. It is believed that quorum-sensing molecules diffuse from the microbial cells and circulate in the surrounding environment as a function of cell density. When these molecules reach a threshold concentration, the gene expression of the entire population is altered in a coordinated manner. This work provides evidence that Aspergillus nidulans produces at least one small diffusible molecule during its growth cycle which accumulates at high cell density and alters the organism's behaviour. When added to low-density cell cultures, ethyl acetate extracts from stationary phase culture supernatants of A. nidulans resulted in the abolition of the lag phase, induced an earlier deceleration phase with 16.3 % decrease in the final cell dry weight and resulted in a 37.8 % increase in the expression of ipnA::lacZ reporter gene construct, which was used as a marker for penicillin production compared to non-treated controls. The bioactive molecule present in the stationary phase extract was purified to homogeneity and was identified by liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy to be γ-heptalactone. This study provides the first evidence that A. nidulans produces γ-heptalactone at a high cell density and it can alter the organism's behaviour at a low cell density. γ-Heptalactone hence acts as a quorum-sensing molecule in the producing strain.[PUBLICATION ABSTRACT]
Journal Article
Ivermectin metabolites reduce Anopheles survival
Ivermectin mass drug administration to humans or livestock is a potential vector control tool for malaria elimination. The mosquito-lethal effect of ivermectin in clinical trials exceeds that predicted from in vitro laboratory experiments, suggesting that ivermectin metabolites have mosquito-lethal effect. The three primary ivermectin metabolites in humans (
i.e
., M1 (3″-
O
-demethyl ivermectin), M3 (4-hydroxymethyl ivermectin), and M6 (3″-
O
-demethyl, 4-hydroxymethyl ivermectin) were obtained by chemical synthesis or bacterial modification/metabolism. Ivermectin and its metabolites were mixed in human blood at various concentrations, blood-fed to
Anopheles dirus
and
Anopheles minimus
mosquitoes, and mortality was observed daily for fourteen days. Ivermectin and metabolite concentrations were quantified by liquid chromatography linked with tandem mass spectrometry to confirm the concentrations in the blood matrix. Results revealed that neither the LC
50
nor LC
90
values differed between ivermectin and its major metabolites for
An. dirus
or
An. minimus.
, Additionally, there was no substantial differences in the time to median mosquito mortality when comparing ivermectin and its metabolites, demonstrating an equal rate of mosquito killing between the compounds evaluated. These results demonstrate that ivermectin metabolites have a mosquito-lethal effect equal to the parent compound, contributing to
Anopheles
mortality after treatment of humans.
Journal Article
العراق تحت الاحتلال : تدمير الدولة وتكريس الفوضى
تعرض دراسات هذا الكتاب جوانب عديدة من قضية العراق في مواجهة الاحتلال وتداعياته، كتبت بأقلام أجنبية، وعربية ومنها عراقية، وهي شهادات توثق قدرة الأمة العربية على المقاومة والمجابهة، وتؤكد حتمية انتصار شعب العراق والأمة العربية إزاء كل محاولات الاحتواء والمصادرة والهيمنة تمثل هذه النصوص شهادات عن مرحلة حاسمة في نضال الأمة العربية، والعراق بشكل خاص، من أجل الحرية والكرامة.
Book
\HOW YARMOUK REFUGEE CAMP BECAME THE WORST PLACE IN SYRIA\
In excerpts from an article published in The Guardian on Mar 5, 2015, Steele examines the history of Yarmouk refugee camp from the beginning of the Syrian conflict in 2011. Despite encountering resistance from Aknaf Bayt al-Maqdis and other Palestinian factions, by Apr 4, ISIS was in control of 90% of the camp. Trapped inside were 18,000 Palestinian refugees without access to food or other necessities, prompting UN Secretary-General Ban Ki-moon to describe Yarmouk as 'the deepest circle of hell.' After the launch of a major military assault on Apr 9, ISIS fighters were eventually driven out of the camp. While Yarmouk had returned to relative calm by the end of the quarter, living conditions in the camp remained desperate and it was estimated that more than half of the remaining population had fled, leaving behind some 7,000 people. Adapted from the source document.
Journal Article
Deploying Deep Learning Models Using Embedded Computing on Autonomous Robot
This paper is set out to investigate the optimization of sensor operation data cost and to deploy deep learning models on a robot for autonomy. The goal of this research was achieved through implementation of a regression based deep learning model which takes advantage of sensor fusion for collision avoidance (LiDAR+ STEREO+CSI). For these goals to be met, an autonomous robot, named “Phoenix One,” was built from recycled materials and purchased parts. Though several examples exist in literature for the use of autonomous systems that employ embedded computing or embedded systems, there is little literature available on how to effectively deploy deep learning algorithms on embedded computers in a step-by-step format. In our research, data was collected through a CSI camera on our Phoenix One robot. Images captured had a size of 224 × 224 pixels and were labelled manually for training our deep learning model ResNet18. I developed a deep learning model for collision avoidance and a deep learning regression model for lane following, using a Jetson Nano embedded computer. Its graphical processing unit gives the Jetson Nano an advantage over other embedded computers due to its added computational processing power and low cost. Through our research I proved that deep learning + regression (DL+R) can effectively be trained and deployed on autonomous vehicles for road following. In future work, I hope to achieve an added goal of Phoenix One autonomously driving between two buildings on campus by integrating GPS and waypoints.
Dissertation
THE EFFECT OF HEIGHT AND SEED PROVENANCE ON EARLY FLOWERING IN BUR OAKS (QUERCUS MACROCARPA)
Bur oaks (Quercus macrocarpa) are long-lived trees that often require two to three decades to mature from seedlings. The rate at which they do so may depend on how rapidly they grow, as maturity is often correlated with height. Many woody monoecious species, like pines and birches, often produce only staminate flowers in their first year of maturity. Using our common garden of 600 bur oak trees from three states (Oklahoma, Illinois, and Minnesota), we asked how long it took for trees to reach maturity, whether maturity was correlated with height, and what types of flowers trees produced early in maturity. We found that 18% of trees flowered after six years of growth and 40% after seven years of growth. Within each population, height was positively correlated with flowering. However, the population with the tallest trees (Oklahoma) had the smallest percentage of trees flowering. Surprisingly, many of the trees produced only pistillate flowers. Our findings suggest that the relationship between maturity and height differs genetically in the Oklahoma population compared to the Illinois or Minnesota populations. Additionally, our finding that bur oaks from all three populations produced pistillate flowers prior to staminate flowers raises questions about the generality of trade-offs between resource availability and allocation to reproduction in flowering plants, in which pistillate flowers are generally assumed to be more costly.
Journal Article