220 Works

Evolutionary biogeography of the reef-building coral genus Galaxea across the Indo-Pacific ocean

Patricia Wepfer, Patricia H. Wepfer, Yuichi Nakajima, Makamas Sutthacheep, Veronica Z. Radice, Zoe Richards, Put Ang, Tullia Terraneo, Mareike Sudek, Atsushi Fujimura, Robert J. Toonen, Alexander S. Mikheyev, Evan P. Economo & Satoshi Mitarai
Stony corals (Scleractinia) form the basis for some of the most diverse ecosytems on Earth, but we have much to learn about their evolutionary history and systematic relationships. In order to improve our understanding of species in corals we here investigated phylogenetic relationships between morphologically defined species and genetic lineages in the genus Galaxea (Euphyllidae) using a combined phylogenomic and phylogeographic ap- proach. Previous studies revealed the nominal species G. fascicularis included three genetically well-differ-...

Revising the Taxonomy and Biology of Ornamental Worms (Polychaeta: Sabellidae) around the Arabian Peninsula

Shannon Brown
Polychaetes are among the most abundant and diverse groups in the benthic environment; however, the diversity of marine polychaetes remains underexplored. On coral reef ecosystems, scientists predict 80-90% of species are still undescribed due to low sampling efforts in certain regions and the understudied nature of smaller invertebrates, such as polychaetes. Sabellidae, a prominent family of polychaetes, are known for their widespread distribution and are recognized as an ornamental worm due to their feather-like appendages....

Ultraviolet Band Based Underwater Wireless Optical Communication

Xiaobin Sun
Underwater wireless optical communication (UWOC) has attracted increasing interest for data transfer in various underwater activities. However, the complexity of the water environment poses considerable challenges to establish aligned and reliable UWOC links. Therefore, solutions that are capable of relieving the requirements on positioning, acquisition and tracking (PAT) are highly demanded. Different from the conventional blue-green light band utilized in UWOC, ultraviolet (UV) light is featured with low solar background noise, non-line-of-sight (NLOS) and good...

A First Principle Investigation of Band Alignment in Emerging III-Nitride Semiconductors

Ahmad Al Sulami
For more than seventy years, semiconductor devices have functioned as the cornerstone for technological advancement, and as the defining transition into the information age. The III-Nitride family of semiconductors, in particular, underwent an impressive maturation over the past thirty years, which allowed for efficient light- emitting devices, photo-detectors, and power electronic devices. As researchers try to push the limits of semiconductor devices, and in particular, as they aim to design ultraviolet light emitters and high...

What Happened to Nemo: Population Dynamics of the Orange Clownfish, Amphiprion percula Over an Eight-Year Time Gap on Kimbe Island, Papua New Guinea

Lucy Fitzgerald
Long-term studies are important for understanding the intricacies of population dynamics over time. Self-recruitment and social hierarchy are valuable tools to quantify the rates at which populations change. In mutualistic symbiosis, where two species benefit from the relationship, different selective pressures and life histories can have unintended consequences on the population dynamics of both species. Anemonefish live in a sized-based hierarchy where individuals queue to be part of the breeding pair (ranks 1 and 2)....

Dissecting the Role of the Histone Demethylase KDM1B in Maintenance of Pluripotency and Differentiation of Human Embryonic Stem Cells

Dalal Alfarhan
Lysine-specific Demethylase 1B (KDM1B) is a chromatin regulator which functions as a histone eraser through the removal of the post-translational modifications mono and dimethylation of histone 3 on lysine 4 (H3K4me1/2). This process is enhanced by the formation of a complex with Nuclear Protein Glyoxylate Reductase (NPAC). NPAC resolves the sequestration of the nucleosome histone tail to allow robust demethylation of H3K4me2 by KDM1B, during transcriptional elongation by RNA polymerase 2 (RNAP II). KDM1B is...

Additively Manufactured Vanadium Dioxide (VO2) based Radio Frequency Switches and Reconfigurable Components

Shuai Yang
In a wireless system, the frequency-reconfigurable RF components are highly desired because one such component can replace multiple RF components to reduce the size, cost, and weight. Typically, the reconfigurable RF components are realized using capacitive varactors, PIN diodes, or MEMS switches. Most of these RF switches are expensive, rigid, and need tedious soldering steps, which are not suitable for futuristic flexible and wearable applications. Therefore, there is a need to have a solution for...

Engineering of Lead-Free Materials for Light-Emitting Application: Structural and Photophysical Studies

Jawaher Almutlaq
Finding luminescent materials with narrow-band emissions, high stability, and high photoluminescence quantum yield (PLQY), yet relatively fast radiative decay rates, has been an outstanding research challenge. This thesis aims to develop different luminescent materials and examine their structural and optical properties for light-emitting applications. The first part of this thesis covers the controversy regarding the origin of emission in zerodimensional perovskites (0D), Cs4PbBr6 and Cs4PbI6, through a comparative analysis between 0D and three-dimensional (3D) perovskites....

Computation of High-Dimensional Multivariate Normal and Student-t Probabilities Based on Matrix Compression Schemes

Jian Cao
The first half of the thesis focuses on the computation of high-dimensional multivariate normal (MVN) and multivariate Student-t (MVT) probabilities. Chapter 2 generalizes the bivariate conditioning method to a d-dimensional conditioning method and combines it with a hierarchical representation of the n × n covariance matrix. The resulting two-level hierarchical-block conditioning method requires Monte Carlo simulations to be performed only in d dimensions, with d ≪ n, and allows the dominant complexity term of the...

INFLUENCE OF HYDROSTATIC PRESSURE AND TEMPERATURE ON THE METABOLIC ACTIVITY OF Alcanivorax marisrubri sp. nov. ISOLATED FROM THE RED SEA

Nathalia Catalina Delgadillo Ordoñez
Hydrostatic pressure (HP) and low temperature are among the main parameters that affect the microbial activity in the deep sea. Especially in the event of an oil spill, the natural microbial degradation of hydrocarbons in the harsh conditions of the deep sea can be significantly impaired. In the Red Sea, the temperature in the deep (22°C) is much higher than in other oceans and may favor hydrocarbon degradation. Bacteria of the genus Alcanivorax, which are...

Narrow-throat Pre-chamber Combustion with Ethanol, a Comparison with Methane

Fahad A. Almatrafi
Pre-Chamber combustion systems are gaining popularity in Internal Combustion Engines (ICE) with the increasing emissions regulations due to their advantages in improving fuel economy by increasing the lean limit and cutting emission, especially NOx. In pre-chamber Combustion, flame jets shoot out from the pre-chamber orifices into the main chamber and generates several ignition points that promote a rapid burn rate of the lean mixture (air-excess ratio (λ) >1) in the main chamber. This work focused...

Hierarchical Approximation Methods for Option Pricing and Stochastic Reaction Networks

Chiheb Ben Hammouda
In biochemically reactive systems with small copy numbers of one or more reactant molecules, stochastic effects dominate the dynamics. In the first part of this thesis, we design novel efficient simulation techniques for a reliable and fast estimation of various statistical quantities for stochastic biological and chemical systems under the framework of Stochastic Reaction Networks. In the first work, we propose a novel hybrid multilevel Monte Carlo (MLMC) estimator, for systems characterized by having simultaneously...

Stochastic Geometry-based Analysis of LEO Satellite Communication Systems

Anna Talgat
Wireless coverage becomes one of the most significant needs of modern society because of its importance in various applications such as health, distance education, industry, and much more. Therefore, it is essential to provide wireless coverage worldwide, including remote areas, rural areas, and poorly served locations. Recent advances in Low Earth Orbit (LEO) satellite communications provide a promising solution to address these issues in poorly served locations. The thesis studies the performance of a multi-level...

Numerical Modeling of Soot Formation in Diffusion Flames

Prabhu Selvaraj
The combustion of petroleum-based fuels leads to the formation of several pollutants. Among them, soot particles are particularly harmful due to their severe consequences on human health. Over the past decades, strict regulations have been placed on automotive and aircraft engines to limit these particulate matter emissions. This work is primarily focused on understanding the fundamental behaviour of soot particles and their formation. Though the focus of this work is on soot formation and growth...

Investigation of Subsurface Systems of Polygonal Fractures

Weiwei Zhu
Fractures are ubiquitous in the subsurface, and they provide dominant pathways for fluid flow in low permeability formations. Therefore, fractures usually play an essential role in many engineering fields, such as hydrology, waste disposal, geothermal reservoir and petroleum reservoir exploitation. Since fractures are invisible and have variable sizes from micrometers to kilometers, there is limited knowledge of their structure. We aim to deepen the understanding of fracture networks in the subsurface from their topological structures,...

BICNet: A Bayesian Approach for Estimating Task Effects on Intrinsic Connectivity Networks in fMRI Data

Meini Tang
Intrinsic connectivity networks (ICNs) refer to brain functional networks that are consistently found under various conditions, during tasks or at rest. Some studies demonstrated that while some stimuli do not impact intrinsic connectivity, other stimuli actually activate intrinsic connectivity through suppression, excitation, moderation or modi cation. Most analyses of functional magnetic resonance imaging (fMRI) data use ad-hoc methods to estimate the latent structure of ICNs. Modeling the effects on ICNs has also not been fully...

Novel computational methods for promoter identification and analysis

Ramzan Umarov
Promoters are key regions that are involved in differential transcription regulation of protein-coding and RNA genes. The gene-specific architecture of promoter sequences makes it extremely difficult to devise a general strategy for their computational identification. Accurate prediction of promoters is fundamental for interpreting gene expression patterns, and for constructing and understanding genetic regulatory networks. In the last decade, genomes of many organisms have been sequenced and their gene content was mostly identified. Promoters and transcriptional...

Investigating effects of electron donor availability on cathodic microbial community structure and functional dynamics in electromethanogenesis

Alaa I. Ragab
Microbial electrochemical technologies (MET) exploit the bioelectrocatalytic activity of microorganisms, with a main focus on waste-to-resource recovery. Electromethanogenesis, a type of MET, describes the process of CO2 reduction specifically to methane, catalyzed by methanogens that utilize the cathode directly as an electron donor or through H2 evolving from the cathode surface. Applications are mainly in the direction of bioelectrochemical power-to-gas, as well as biogas upgrading and carbon capture and utilization. As the cathode and its...

Heterogeneous Integration Strategy for Obtaining Physically Flexible 3D Compliant Electronic Systems

Sohail F. Shaikh
Electronic devices today are an integral part of human life thanks to state-of-the- art complementary metal oxide semiconductor (CMOS) technology. The progress in this area can be attributed to miniaturization driven by Moore’s Law. Further advancements in electronics are under threat from physical limits in dimensional scaling and hence new roadmaps for alternative materials and technologies are chased. Furthermore, the current era of Internet of things (IoT) and Internet of everything (IoE) has broaden the...

The Isolation and Characterization of Untapped Diversity of Culturable Bacteria in the Red Sea Mangrove Ecosystem

Fatmah Sefrji
Microorganisms are widespread in all ecosystems and play critical roles in nature. They are major players in global biogeochemical cycles that are fundamental in nutrient cycling. Molecular ecology surveys that investigate the microbial diversity of many different environments have revealed an impressive diversity of microbes in nature and have highlighted our inability to cultivate the vast majority of them in the laboratory. The improvement of our ability to grow uncultivable microbes in laboratory conditions will...

Effect of SiO2/Al2O3 Ratio of Zeolite Beta in a Bi-functional System for Direct CO2 Hydrogenation into Value Added Chemicals

Ahmed S. Alkhalaf
Carbon dioxide levels in atmosphere are linked with a number of adverse environmental impacts including climate change. CO2 utilization is one of the available technologies to reduce CO2 emissions released into atmosphere by its conversion into value added products. Hydrogenation of CO2 into hydrocarbons (with methanol being an intermediate) can be achieved in a single-pot using bi-functional catalysis system composed of metal/metal-oxide and zeolite. In this study, activated novel indium cobalt (InCo) and zeolite beta...

Blind Estimation of Central Blood Pressure Waveforms from Peripheral Pressure Signals

Ahmed Magbool
The central aortic blood pressure signal is an important source of information that contains cues about the cardiovascular system condition. Measuring this pulse wave clinically is burdensome as it can be only measured invasively with a catheter. As a result, many mathematical tools have been proposed in the past few decades to reconstruct the aortic pressure signal from the peripheral pressure signals that are usually easier to obtain noninvasively. At the distal level, the blood...

Two-scale Homogenization and Numerical Methods for Stationary Mean-field Games

Xianjin Yang
Mean-field games (MFGs) study the behavior of rational and indistinguishable agents in a large population. Agents seek to minimize their cost based upon statis- tical information on the population’s distribution. In this dissertation, we study the homogenization of a stationary first-order MFG and seek to find a numerical method to solve the homogenized problem. More precisely, we characterize the asymptotic behavior of a first-order stationary MFG with a periodically oscillating potential. Our main tool is...

Coupled Hydro-Chemo-Mechanical Processes in Fractured Rocks

Rached Rached
Fractured rocks play a crucial role in countless engineered systems that relate to energy recovery, water resources, waste injections, and infrastructure designs. This dissertation investigates coupled physical processes in fractured rocks from the continuum to the pore scale using novel experimental designs and numerical techniques. The research comprises three main topics: 1- large-scale geophysical testing of fractured rocks, 2- coupled hydro chemo-mechanical processes in fractured rocks at the pore and contact scale, and 3- the...

Broadband Reflective Metalens in Visible Band Based on Bragg Reflector Multilayers for VECSEL Applications

Zahrah J. Alnakhli
In conventional optics, curved lenses focus light rays to a focal point after light passes through them. These lenses have been designed to shape the wavefront of the incident beam as it emerges from the curved surface of the lens. Conventional lenses suffer from many limitations, such as limited optical quality for imaging and integration difficulties with other optical components due to their large size, huge thickness, as well as being difficult to manufacture. Using...

Registration Year

  • 2020
    220

Resource Types

  • Dissertation
    207
  • Dataset
    12
  • Output Management Plan
    1

Affiliations

  • King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
    207
  • King Abdullah University of Science and Technology
    13
  • James Cook University
    4
  • University of Queensland
    2
  • University Austral de Chile
    2
  • Curtin University
    2
  • University of Konstanz
    2
  • Institute of Experimental Botany
    2
  • University of Guam
    1
  • National Research Institute for Agriculture, Food and Environment
    1