237 Works

Investigating the Role of Lactate in Regulating Gene Expression through Epigenetic Modifications in Neuronal Cells

Manar M. Darwish
Lactate has been long thought of as a dead-end waste product of glycolysis. In the brain, recent evidence has revealed a key role of L-lactate creating a paradigm-shift in our understanding of the neuronal energy metabolism. The Astrocyte neuron lactate shuttle (ANLS) model, has shown L-Lactate as the main energy substrate delivered by astrocytes to neurons to sustain neuronal oxidative metabolism. This metabolic coupling is an essential mechanism for long-term memory formation. Experimental evidence indicates...

Hydrogen Combustion versus Diesel Isobaric Combustion in the Double Compression-Expansion Engine

Rafig Babayev
This thesis aims to contribute to the research and development of a new highly efficient split-cycle engine concept – the double compression-expansion engine (DCEE) – by expanding the knowledge of combustion processes suitable for this and, potentially, other modern engines, via experimental and computational studies. In this work, first, the importance of continued improvement of internal combustion engines is demonstrated by comparing the life-cycle CO2 emissions of different modes of transport, including walking and bicycling....

Exploring the Reactivity of Well-defined Oxide-supported Metal­Alkyl and Alkylidyne Complexes via Surface Organometallic Chemistry

Aya Saidi
Surface Organometallic Chemistry (SOMC) is an excellent approach to erase the gap between homogeneous and heterogeneous catalysis by grafting the molecular organometallic complex on various oxide surfaces, forming well-defined and single-site catalysts. This strategy allows for better characterization as well as the improvement and development of existing and new catalysts. These surface species could promote a wide range of catalytic applications (i.e., metathesis of hydrocarbons, hydrogenolysis of alkanes, and olefin polymerization reactions) depending on the...

An Empirical Study of the Distributed Ellipsoidal Trust Region Method for Large Batch Training

Ali Alnasser
Neural networks optimizers are dominated by first-order methods, due to their inexpensive computational cost per iteration. However, it has been shown that firstorder optimization is prone to reaching sharp minima when trained with large batch sizes. As the batch size increases, the statistical stability of the problem increases, a regime that is well suited for second-order optimization methods. In this thesis, we study a distributed ellipsoidal trust region model for neural networks. We use a...

Zaxinone, a Natural Apocarotenoid, Regulates Growth and Strigolactone Biosynthesis in Rice

Jian You Wang
Carotenoids are the precursor of several metabolites with regulatory functions, which include the plant hormones abscisic acid (ABA) and strigolactones (SLs), and signaling molecules, such as β-cyclocitral. These carotenoid-derivatives originate from oxidative breakdown of the double bond resulting in carbonyl cleavage-products designated as apocarotenoids. The cleavage reaction causing apocarotenoid formation is catalyzed frequently by Carotenoid Cleavage Dioxygenases (CCDs). Several lines of evidence indicate the presence of yet unidentified apocarotenoids with regulatory or signaling function. Here,...

Effect of Anthropogenic Noise on Reef Macroinvertebrates (Lambis lambis and Tridacna maxima)

Michelle-Nicole Havlik
Boat noise has been shown to distract and cause harm to many marine organisms. Most of the study effort has been focused on fish & marine mammals, even though invertebrates represent 99% of all living organisms, both terrestrial and aquatic. The small amount of studies conducted on invertebrates have demonstrated a clear negative correlation between anthropogenic noise pollution and invertebrate well-being. The small giant clam Tridacna maxima and the spider conch Lambis lambis are two...

Performance comparison of Hierarchical Non-Terrestrial Networks for 6G

Dengke Wang
This thesis investigates the fundamental performance of Hierarchical Non-Terrestrial Networks for the 6th generation (6G). 6G communication research is currently focus- ing on non-terrestrial networks (NTNs) to promote ubiquitous and ultra-high-capacity global connectivity. Specifically, multi-layered hierarchical networks, i.e., the orches- tration among different aerial/space platforms, including Unmanned Aerial Vehicles (UAVs), High Altitude Platforms (HAPs), and satellites co-operating at different al- titudes, currently represents one the most attractive technological options to solve coverage and latency constraints...

Frequency-modulation Stimulated Raman Scattering microscopy with an Acousto-Optic Tunable Filter

Elisa Grassi
Stimulated Raman Scattering (SRS) is a Coherent Raman microscopy method that has been increasingly employed in recent years for highly-specific, label-free, and high-speed bioimaging. Compared to a similar Coherent Raman method, the so-called Coherent Anti-Stokes Scattering (CARS) microscopy, it exhibits advantages such as the absence of nonresonant background (NRB) and the linearity of the signal intensity on the concentration of molecules of interest. However, SRS can be affected by unwanted background signals that hinder the...

Theoretical and Experimental Investigations of the Dynamics of Axially Loaded - Microstructures with Exploitation for MEMS Resonator-Based Logic Devices

Sherif Adekunle Tella
In line with the rising demand for smarter solutions and embedded systems, Microelectromechanical systems (MEMS) have gained increasing importance for digital computing devices and Internet-of-Things (IoT) applications, most notably for mobile wearable devices. This achievement is driven by MEMS resonators' inherent properties such as simplicity, sensitivity, reliability, and low power consumption. Hence, they are being explored for ultra-low-power computing machines. Several fundamental digital logic gates, switching, and memory devices have been demonstrated based on MEMS...

BranchNet: Tree Modeling with Hierarchical Graph Networks

Jiayao Zhang
Research on modeling trees and plants has attracted a great deal of attention in recent years. Early procedural tree modeling can be divided into four main categories: rule-based algorithms, repetitive patterns, cellular automata, and particle systems. These methods offer a very high level of realism; however, creating millions of varied tree datasets manually is not logistically possible, even for professional 3D modeling artists. Trees created using these previous methods are typically static and the controllability...

Highly Fluorinated Macrocycles and Macrocycle-Based Polymers and Their Prospective Applications in Energy-Intensive Separations

Abdulmajeed W. Hashem
The fluorination of porous materials often leads to the enhancement of properties such as stability, crystallinity and selective adsorption. Although there has been much interest in the fluorination of many types of porous materials, little research has been done on the fluorination of macrocycles, specifically trianglimine and leaning pillararene based materials. In this work, we introduce for the first time highly fluorinated trianglimine and leaning pillararene and show the enhancement effects brought about by the...

Environmental origin and compartmentalization of bacterial communities associated with Avicennia marina mangroves on the Red Sea coast

Juan David Escobar Prieto
Mangrove forests are highly productive ecosystems widespread in tropical and subtropical coastlines, with a coverage of 75% of the world’s tropical shorelines. Mangrove plants developed specific physiological and morphological adaptation to thrive in such unique environments. Together with plant adaptations, mangroves develop a tight partnership with microorganisms, mainly bacteria and fungi, that form the so-called mangrove-microbiome. Plant-associated microorganisms are generally recruited by the root system (root tissues and rhizosphere) and the colonization process starts with...

A Multi-platform Comparison of Phenology for Semi-automated Classification of Crops

Sarah Kanee
Remote sensing has enabled unprecedented earth observation from space and has proven to be an invaluable tool for agricultural applications and crop management practices. Here we detect seasonal metrics indicating the start of the season (SOS), the end of the season (EOS) and maximum greenness (MAX) based on vegetation spectral signatures and the normalized difference vegetation index (NDVI) for a time series of Landsat-8, Sentinel-2 and PlanetScope imagery of potato, wheat, watermelon, olive and peach/apricot...

Carbonate Acidizing: Modeling and Uncertainty Propagation Analysis

Qasim Sahu
Reservoir stimulation is a common technique used to improve the productivity of carbonate reservoirs. One of the effective stimulation methods is carbonate acidizing. This process involves injecting a reactive fluid to dissolve the rock mineral, creating a conductive path for hydrocarbon flow. With the development of tight and unconventional reservoirs, stimulation has become more critical for optimal economic production. This study aims to simulate the dissolution of carbonate in matrix acidizing. A reactive transport model...

Shock Fitting For Converging Cylidrical Shocks In Hydrodynamics And Ideal Magnetohydrodynamics

Talha Arshad
Converging shocks have long been a topic of interest in theoretical fluid mechanics, and are of prime importance in inertial confinement fusion. However, tracking converging shocks in numerical schemes poses several challenges. Numerical schemes based on shock capturing inherently diffuse out shocks to multiple grid cells, making it hard to track the shock. Converging shocks are significantly harder to track, as this numerical smearing is much more significant when converging shocks approach the axis of...

New Algorithms to Solve the Positioning Problem of Outdoor Localization Using Constrained and Unconstrained Optimization Techniques

Muhanned Alsaif
The demand for outdoor precise location is increasing with the development of new applications such as autonomous vehicles, exploration robots and wireless sensor networks. Global Navigation Satellite System (GNSS) is the go-to system for outdoor localization. This thesis focuses on developing new methods for GNSS single-point positioning (SPP) model, where no access to a reference station or precise GNSS parameters is needed. We investigated the limitations of the standard method, least- squares adjustment (LSA), and...

Autoignition and reactivity studies of renewable fuels and their blends with conventional fuels

Gani Issayev
Population growth and increasing standards of living have resulted in a rapid demand for energy. Our primary energy production is still dominated by fossil fuels. This extensive usage of fossil fuels has led to global warming, environmental pollution, as well as the depletion of hydrocarbon resources. The prevailing difficult situation offers not only a challenge but also an opportunity to search for alternatives to fossil fuels. Hence, there is an urgent need to explore environmentally...

Investigation of OH + Fuel Elementary Reactions

Dapeng Liu
Increasingly stringent legislations call for more efficient and cleaner combustion technology as well as sustainable fuels. Chemical kinetic models are required in designing and optimizing novel engine concepts as well as selecting appropriate renewable fuels. Among the many reactions controlling fuel reactivity, OH + Fuel elementary reaction is one of the most important reactions that plays a critical role from low to high temperatures. In this thesis, OH + Fuel elementary reactions are studied for...

Stratigraphy of The Central Red Sea Margin: New Insights on the Tectono-stratigraphy of the Pre- and Syn- rift sedimentary sections and Arabian Plateau Uplift

Ali J. AlTammar
Broad uplift of the Red Sea margins has extensively eroded the pre-rift sedimentary section and exhumed the Proterozoic basement in the Arabian and Nubian Shields. However, some pre-rift sedimentary rocks are preserved within rift grabens along the coast, and on top of the Arabian plateau beneath syn-rift basalts of Harrat Hadan. Previous studies on outcrops of pre- and syn-rift sedimentary rocks near Jeddah assigned them various ages and Formations leading to confusion. Moreover, no attempts...

On Seven Fundamental Optimization Challenges in Machine Learning

Konstantin Mishchenko
Many recent successes of machine learning went hand in hand with advances in optimization. The exchange of ideas between these fields has worked both ways, with ' learning building on standard optimization procedures such as gradient descent, as well as with new directions in the optimization theory stemming from machine learning applications. In this thesis, we discuss new developments in optimization inspired by the needs and practice of machine learning, federated learning, and data science....

Characterization of Strigolactone Antagonists as Inhibitor of Striga hermonthica Seed Germination and the Discovery of a Nitric Oxide Responsive Protein in Arabidopsis thaliana

Randa Alhassan Yahya Zarban
Plants have evolved different communication mechanisms that convey information encoded in chemical signals, both internally and to surrounding organisms. Two such signals are strigolactones (SLs) and nitric oxide (NO). SLs are plant hormones that shape plant architecture according to nutrition availability and mediate interactions with beneficial arbuscular mycorrhizal fungi. For this second purpose, plant roots release SLs into the soil where they also trigger seed germination in root parasitic weeds, such as Striga hermonthica. Attachment...

Circulation and Water Mass Formation in the Northern Red Sea Response to Wind and Thermohaline Forcing

Lina Eyouni
Numerical simulation and remote sensing have indicated that the northern half of the Red Sea has a significant role in the thermohaline circulation within the basin. However, very few studies with in situ observation have been performed in a region where the formation of Red Sea Outflow Water (RSOW) and occasionally of Red Sea Deep Water (RSDW) take place during the winter in the northern Red Sea (NRS). This study provides new insights into the...

Bacterial Growth Potential of Antiscalants used in Reverse Osmosis Systems using Seawater Autochthonous Microbial Communities

Ghadeer Abdullah Hasanin
Antiscalants are chemicals used in membrane-based water desalination processes to prevent the scaling of salts on the membrane. Previous studies suggested that antiscalants could lead or contribute biological fouling by providing growth-promoting factors such as source of biodegradable carbon or phosphorus. However, the test in previous studies were conducted using drinking water and pure cultures of bacteria isolated from freshwater. These conditions do not reflect those of desalination systems. In this study, we determined the...

RADICL-ChIP: a Method to Capture Global RNA-on-Genome Distribution Mediated by Chromatin associated Factors

Somiya Saferuddin
Chromatin associated RNAs play a key role in mediating epigenetic mechanism. To improve our comprehension of how chromatin-associated RNAs influence gene expression, it is crucial to identify the genomic locus that RNA interacts with on a genome-wide scale. Emerging technologies were developed to capture binding sites of lncRNAs globally. Such techniques rely on the concept of Proximity ligation via a biotinylated adapter to ligate DNA and RNA on each end, such as MARGI, GRID-seq, ChAR-seq...

High-Bitrate Photodetection in Ultraviolet-to-Visible for Optical Wireless Communication

Chun Hong Kang
Optical wireless communication, taking advantage of the unlicensed ultraviolet-to visible wavelength region of the electromagnetic spectrum, had been coined as the next-generation wireless communication technology and holds promises to deliver a high-speed, reliable, and secured broadband experience. The push towards the optical-based medium is manifested by the demand for additional channel bandwidth to accommodate the rapid growth of the Internet-of-Things (IoT) and Internet-of-Underwater-Things (IoUT). Therefore, high-bitrate optoelectronics devices and components forming the transceiver units used...

Registration Year

  • 2021

Resource Types

  • Dissertation


  • King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia