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Articles 1591 - 1620 of 2330
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Edaphic And Vegetative Controls On Mercury Cycling In Oligohaline Wetlands, Jonathan M. Willis
Edaphic And Vegetative Controls On Mercury Cycling In Oligohaline Wetlands, Jonathan M. Willis
LSU Doctoral Dissertations
With the expansion of the human population and associated industries there is a concomitant increase in both resource utilization and the production of waste and deleterious by-products. Mercury is a naturally-occurring toxic metal with a complicated and unique biogeochemical cycle, and is often a contaminant of ecotoxicological concern in unindustrialized aquatic habitats. The research described herein was designed to elucidate multiple aspects regarding the behavior of mercury in oligohaline wetland habitats, particularly with respect to edaphic and vegetative effects, through a monitoring and characterization study as well as a series of manipulative experiments. The observational study, conducted in the wetlands …
Mass Transfer And Mergers In Double White Dwarf Binaries, Wesley Paul Even
Mass Transfer And Mergers In Double White Dwarf Binaries, Wesley Paul Even
LSU Doctoral Dissertations
We have developed a self consistent field (SCF) technique similar to the one described by Hachisu, Eriguchi, & Nomoto (1986b) that can be used to construct detailed force-balanced models of synchronously rotating, double white dwarf (DWD) binaries. This SCF technique can be used to construct model sequences that mimic the last portion of the detached inspiral phase of DWD binary evolutions, and semi-detached model sequences that mimic a phase of conservative mass transfer. In addition, the SCF models can be used to provide quiet initial starts for dynamical studies of the onset of mass transfer in DWD systems. We present …
Synthesis And Characterization Of Rare Earth-Nickel-Gallium Ternary Intermetallics, Kandace R. Thomas
Synthesis And Characterization Of Rare Earth-Nickel-Gallium Ternary Intermetallics, Kandace R. Thomas
LSU Doctoral Dissertations
The structural and physical characterization of several early and latter rare earth Ln-Ni-Ga systems, which include Ln2NiGa12 (Ln = Pr, Nd, Sm), alpha-LnNiGa4 (Ln = Y, Gd – Yb) and beta-LnNiGa4 (Ln = Tb – Ho) will be presented in this work. These systems are thermodynamically located within a copious, robust phase space and provide a rich understanding of how slight modifications to synthetic preparations can yield the adoption of different structure types in a Ga-rich regime. Each of these phases is made up of well-studied substructures which lend an additional angle of apperception as to how their structure and …
Non-Axisymmetric Instabilities In Self-Gravitating Tori Around Black Holes, And Solving Einstein Constraints With Superconvergent Finite Element Methods, Oleg Korobkin
LSU Doctoral Dissertations
This thesis contains results on two related projects. In the first project, we explore non-axisymmetric instabilities in general relativistic accretion disks around black holes. Such disks are created as transient structures in several astrophysical scenarios, including mergers of compact objects and core collapse of massive stars. These disks are suggested for the role of cenral engines of gamma-ray bursts. We address the stability of these objects against the runaway and non-axisymmetric instabilities in the three-dimensional hydrodynamical fully general relativistic treatment. We explore three slender and moderately slender disk models with varying disk-to-black hole mass ratio. None of the models that …
Probabilistic Models For Short Term Traffic Conditions Prediction, Yan Qi
Probabilistic Models For Short Term Traffic Conditions Prediction, Yan Qi
LSU Doctoral Dissertations
Accurate short-term prediction of traffic condition on freeways and major arterials has become increasingly important because of its vital role in traffic management functions and various trip decisions. Given the dynamic nature of freeway traffic, this study proposed two stochastic model approaches, Hidden Markov Model (HMM) and One-Step Stochastic Model, for short-term traffic prediction during peak periods. The data used in the study are real-time traffic monitoring data gathered over 6 years on a 40-mile segment of Interstate-4 in Orlando, Florida. Both approaches are based on the traffic state transition probabilities. The HMM approach defines traffic states in a two …
Homogenization Of Nonlinear Partial Differential Equations, Silvia Jiménez
Homogenization Of Nonlinear Partial Differential Equations, Silvia Jiménez
LSU Doctoral Dissertations
This dissertation is concerned with properties of local fields inside composites made from two materials with different power law behavior. This simple constitutive model is frequently used to describe several phenomena ranging from plasticity to optical nonlinearities in dielectric media. We provide the corrector theory for the strong approximation of fields inside composites made from two power law materials with different exponents. The correctors are used to develop bounds on the local singularity strength for gradient fields inside microstructured media. The bounds are multiscale in nature and can be used to measure the amplification of applied macroscopic fields by the …
Carbon Nanotube Interconnect Modeling For Very Large Scale Integrated Circuits, Yao Xu
Carbon Nanotube Interconnect Modeling For Very Large Scale Integrated Circuits, Yao Xu
LSU Doctoral Dissertations
In this research, we have studied and analyzed the physical and electrical properties of carbon nanotubes. Based on the reported models for current transport behavior in non-ballistic CNT-FETs, we have built a dynamic model for non-ballistic CNT-FETs. We have also extended the surface potential model of a non-ballistic CNT-FET to a ballistic CNT-FET and developed a current transport model for ballistic CNT-FETs. We have studied the current transport in metallic carbon nanotubes. By considering the electron-electron interactions, we have modified two-dimensional fluid model for electron transport to build a semi-classical one-dimensional fluid model to describe the electron transport in carbon …
Calibrating And Improving The Sensitivity Of The Ligo Detectors, Jeffrey S. Kissel
Calibrating And Improving The Sensitivity Of The Ligo Detectors, Jeffrey S. Kissel
LSU Doctoral Dissertations
The Laser Interferometer Gravitational wave Observatory (LIGO) is network of three, power recycled Fabry-Perot Michelson interferometers built to detect gravitational waves from astrophysical sources at frequencies between 40 and 6000 Hz. For their fifth science run, from 2005 to 2007, the detectors observed at designed sensitivity, achieving equivalent strain amplitude noise of 3x10^−23 strain/rtHz at 100 Hz. To date, the observatory has not detected gravitational waves. However, even at such sensitivity, the expected detection rate for known astrophysical sources of gravitational waves is likely 0.02 yr^−1. The fundamental noise source of these ground-based detectors limiting the sensitivity below 40 Hz …
Generalized Curvilinear Advection Formalism For Finite Volume Codes Doing Relativistic Hydrodynamics, Jay Michael Call
Generalized Curvilinear Advection Formalism For Finite Volume Codes Doing Relativistic Hydrodynamics, Jay Michael Call
LSU Doctoral Dissertations
While it is possible to numerically evolve the relativistic fluid equations using any chosen coordinate mesh, typically there are distinct computational advantages associated with different types of candidate grids. For example, astrophysical flows that are governed by rotation tend to give rise to advection variables that are naturally conserved when a cylindrical mesh is used. On the other hand, Cartesian-like coordinates afford a more straightforward implementation of adaptive mesh refinement (AMR) and avoid the appearance of coordinate singularities. Here it is shown that it should be possible to reap the benefits associated with multiple types of coordinate systems simultaneously in …
Highly Efficient Selection, Enumeration, Enrichment, And Molecular Profiling Of Low-Abundance Biological Cells, Udara R. Dharmasiri Rasika Dharmasiri
Highly Efficient Selection, Enumeration, Enrichment, And Molecular Profiling Of Low-Abundance Biological Cells, Udara R. Dharmasiri Rasika Dharmasiri
LSU Doctoral Dissertations
After brief overviews of low-abundance cell selection techniques in chapter 1 and circulating tumor cells in chapter 2, this dissertation initially focuses on the development of aptamer incorporated high-throughput microfluidic techniques to select rare circulation prostate cancer cells (LNCaP) directly from whole blood with subsequent quantification of these rare cells using a non-labeling approach. Then, I extended the technology to environmental samples in an effort around time, sensitivity, and portability of traditional groundwater assessment. As a model bio- pathogen, E. coli O157:H7 was chosen due to its toxicity and its adverse impact on recreational waters. Low-abundance (<100 cells mL-1) E. coli O157:H7 cells were isolated and enriched from environmental water samples using a microfluidic chip that its capture beds were covalently decorated with E.coli O157:H7 specific polyclonal antibodies. The selected cells were enumerated using RT-qPCR technique. Finally, I have integrated HTMSU with electrokinetic enrichment microfluidic unit for performance of single recombinant low-abundance CTC cell-based assay. A series of analytical processes were carried out, including immunoaffinity selection of rare CTCs, quantification of selected cells via conductivity impedance and electrophoretic enrichment of selected cells for PCR/LDR/CE interrogation for detection of low-abundance point mutations in genomic DNA.
Fabrication Of Receptor-Modified Microfluidic Surfaces For Applications In Glycoprotein Screening, Jennifer Macalindong De Guzman
Fabrication Of Receptor-Modified Microfluidic Surfaces For Applications In Glycoprotein Screening, Jennifer Macalindong De Guzman
LSU Doctoral Dissertations
Glycoproteins have long been identified to have a profound association with human pathological processes, and they are much sought after as potential biomarkers to aid in the early diagnosis and clinical prognosis of cancers and diseases. There is currently high demand for high-throughput and low–limit–of–detection techniques that can afford profiling of the glycoproteome. Micro-total analysis systems (µTAS) based on microfluidics have the potential to fulfill these requirements, but in order to reduce the complexity of the protein pool, the µTAS devices must contain a pre-isolation and enrichment component. The research project undertaken here involved derivatization of microfluidic …
Perverse Poisson Sheaves On The Nilpotent Cone, Jared Lee Culbertson
Perverse Poisson Sheaves On The Nilpotent Cone, Jared Lee Culbertson
LSU Doctoral Dissertations
For a reductive complex algebraic group, the associated nilpotent cone is the variety of nilpotent elements in the corresponding Lie algebra. Understanding the nilpotent cone is of central importance in representation theory. For example, the nilpotent cone plays a prominent role in classifying the representations of finite groups of Lie type. More recently, the nilpotent cone has been shown to have a close connection with the affine flag variety and this has been exploited in the Geometric Langlands Program. We make use of the following important fact. The nilpotent cone is invariant under the coadjoint action of G on the …
Method Of Riemann Surfaces In Modelling Of Cavitating Flow, Anna Zemlyanova
Method Of Riemann Surfaces In Modelling Of Cavitating Flow, Anna Zemlyanova
LSU Doctoral Dissertations
This dissertation is concerned with the applications of the Riemann-Hilbert problem on a hyperelliptic Riemann surface to problems on supercavitating flows of a liquid around objects. For a two-dimensional steady irrotational flow of liquid it is possible to introduce a complex potential w(z) which allows to apply the powerful methods of complex analysis to the solution of fluid mechanics problems. In this work problems on supercavitating flows of a liquid around one or two wedges have been stated. The Tulin single-spiral-vortex model is employed as a cavity closure condition. The flow domain is transformed into an auxiliary domain with known …
Diatom Stratigraphy Defining Ice Sheet Grounding Chronology, Ross Sea, Antarctica, Juan Manuel Chow
Diatom Stratigraphy Defining Ice Sheet Grounding Chronology, Ross Sea, Antarctica, Juan Manuel Chow
LSU Doctoral Dissertations
Evidence of Antarctic ice sheet behavior and paleoenvironment is often approached from proxy records because there is a dearth of direct records from Antarctica itself. The studies presented here seek to augment our knowledge of translations of the West Antarctic Ice Sheet’s (WAIS) marine termination based on direct biostratigraphic evidence. Diatom analyses were conducted from two areas of Ross Sea, Antarctica. In the first study, diatoms were used to constrain the age of diamictons from five seismic units in the Eastern Basin and thus expand our knowledge of WAIS behavior during the Southern Hemisphere Last Glacial Maximum (LGM). All five …
Oxidation Of Reduced Sulfur Compounds: A Triple-Oxygen-Isotope Perspective, Issaku E. Kohl
Oxidation Of Reduced Sulfur Compounds: A Triple-Oxygen-Isotope Perspective, Issaku E. Kohl
LSU Doctoral Dissertations
The Earth’s geochemical evolution is recorded in the rocks that compose its lithosphere. Specifically, sulfate minerals have been identified as being repositories of information concerning the past hydrosphere, atmosphere and biosphere. This is due to the non-labile nature of SO42- and its ability to store a record of the oxidative reactions and oxygen sources involved in its formation. Microbial dissimilatory sulfate reduction (MDSR) and sulfide oxidation cause oxygen from H2O and O2 to be trapped to varying degrees in ambient, dissolved SO42-. In order to better interpret the H2O and O2 signals in SO42-, we must deepen our understanding of …
The Care Plan As An Indicator Of Change In Nursing Science Instruction: A Textbook-Based Analysis, Lindsay Bratton-Mullins
The Care Plan As An Indicator Of Change In Nursing Science Instruction: A Textbook-Based Analysis, Lindsay Bratton-Mullins
LSU Doctoral Dissertations
Sciences are critical in nursing education to aid the nurse in understanding health and disease processes. Accrediting bodies for nursing education have emphasized that educators teach in ways that encourage critical thinking and, therefore, produce safe-practicing, competent nurse graduates. Nursing care plans best reflect nursing education’s central goals. Because of its longevity of use and familiarity, in this study, the nursing care plan was used as a proxy for nursing science’s learning objectives. This research was a study of the nursing care plan as an indicator for change in nursing science education in the United States to determine if change …
Design And Development Of Chiral And Achiral Molecularly Imprinted Stationary Phases, Jason Paul Lejeune
Design And Development Of Chiral And Achiral Molecularly Imprinted Stationary Phases, Jason Paul Lejeune
LSU Doctoral Dissertations
Although the cross-linker can comprise over 80% of the polymer composition, improving the nature of the cross-linker in molecularly imprinted polymers has not been studied extensively. The goal of this research is to develop novel cross-linking monomers to either use in the One MoNomer Molecularly Imprinted Polymer system (OMNiMIP) or use in conjunction with other commercially available cross-linkers and functional monomers. Chapter 2 contains research into the understanding of the performance of a new cross-linking monomer (N, O - bismethacryloyl ethanolamine, NOBE) discovered in the Spivak Research Group. The ability of this monomer to outperform traditional two monomer systems in …
Gamma Ray Burst Redshift Catalog And Applications, Limin Xiao
Gamma Ray Burst Redshift Catalog And Applications, Limin Xiao
LSU Doctoral Dissertations
The measurement of redshifts for gamma-ray bursts (GRBs) is an important issue for the study of the high redshift universe and cosmology. We developed a program to estimate the redshifts for GRBs from the original light curves and spectra, aiming to get redshifts for bursts without spectroscopic or photometric redshifts. We derive the luminosity indicators from the light curves and spectra of each burst, including the lag time between low and high photon energy light curves, the variability of the light curve, the peak energy of the spectrum, the number of peaks in the light curve, and the minimum rise …
Modeling The Impacts Of Pulsed Riverine Inflows On Hydrodynamics And Water Quality In The Barataria Bay Estuary, Anindita Das
Modeling The Impacts Of Pulsed Riverine Inflows On Hydrodynamics And Water Quality In The Barataria Bay Estuary, Anindita Das
LSU Doctoral Dissertations
Eutrophication and coastal wetland loss are the major environmental problems affecting estuaries around the world. In Louisiana, controlled diversions of the Mississippi River water back into coastal wetlands are thought to be an important engineering solution that could reverse coastal land loss. There are concerns, however, that freshwater diversions may increase nutrient inputs and create severe eutrophication problems in estuaries and wetlands adjacent to the diversion sites. My dissertation research concerns modeling the effects of the observed and hypothetical freshwater diversion discharges on the hydrodynamics, salinity and water quality in the Barataria estuary, a deltaic estuary in south Louisiana. This …
Developing Tools To Identify Factors That Limit Production In Coastal Marshes, Vanessa Danielle Tobias
Developing Tools To Identify Factors That Limit Production In Coastal Marshes, Vanessa Danielle Tobias
LSU Doctoral Dissertations
Marsh loss is a problem in many areas around the world. In Louisiana’s coastal marshes, where Spartina patens is the most common plant, restoration and management seek to slow wetland loss rates that average approximately 77.4 km2/year. To combat the problem, scientists and managers require tools to determine local causes and evaluate the effectiveness of management techniques. Current methods for identifying factors that limit productivity in marshes are too time-consuming or expensive for wide-spread, regular use. Critical values of elemental concentrations in plant tissue are widely used to diagnose mineral deficiencies and toxicities in agricultural crops, however. I used the …
Essays On Three Price Judgments: Price Fairness, Price Magnitude, And Price Expectation, Sandeep Bhowmick
Essays On Three Price Judgments: Price Fairness, Price Magnitude, And Price Expectation, Sandeep Bhowmick
LSU Doctoral Dissertations
This dissertation addresses three important price judgments: price fairness, price magnitude, and price expectation. Developed over three chapters, the main objective of this research is to determine underlying differences in these three price judgments. These differences are based on conceptualizing price fairness as a combination of affective and cognitive components, whereas price magnitude and price expectation reflect different cognitive aspects of price judgment. Chapter 1 provides a literature review and identifies several research questions related to these three price judgments; Chapters 2 and 3 provide testable hypotheses and conduct three pretests and two experiments to test the hypotheses. Using structural …
The Influence Of Computer User Knowledge And Selected Demographic Characteristics The Academic Achievement Of High School Seniors, Michael E. Brown
The Influence Of Computer User Knowledge And Selected Demographic Characteristics The Academic Achievement Of High School Seniors, Michael E. Brown
LSU Doctoral Dissertations
The primary purpose of this study was to identify the influence of computer user knowledge as measured by the Computer User Knowledge Survey (CUKS), and the personal demographic characteristics of Gender, Age, and Race on academic achievement as measured by the Graduation Exit Examination-21 (GEE-21), among high school seniors in public schools in a parish in South Louisiana. The CUKS and the Gender and Race data were collected from the self-perceived CUKS survey administered to 295 seniors registered in English IV classes at a school in South Louisiana. The academic achievement data and the ages of the student subjects were …
Macroinstability And Perturbation In Turbulent Stirred Tank Flows, Somnath Roy
Macroinstability And Perturbation In Turbulent Stirred Tank Flows, Somnath Roy
LSU Doctoral Dissertations
Impeller stirred tank reactors (STRs) are commonly used in the chemical processing industries for a variety of mixing and blending technologies. In this research, a numerical study of flow and mixing inside turbulently agitated STRs are carried out. An immersed boundary method (IBM) is utilized to represent moving impeller geometries in the background of multi-block structured curvilinear fluid. The IBM This curvilinear-IBM methodology is further combined with the large eddy simulation (LES) technique to address the issue of modeling unsteady turbulent flows in the STR. Verification of the combined IBM-LES implementation strategy in curvilinear coordinates is done through comparisons with …
An Analysis Of Predictors Of Exclusionary Discipline Practices And The Relationship With Student Achievement Using Hierarchical Linear Modeling, Amanda Dahir
LSU Doctoral Dissertations
School discipline plays an important role in maintaining a safe and orderly learning environment for students. Disruptive behavior in the classroom interferes with classroom learning time making it difficult to accomplish academic goals. A common method of handling discipline problems within schools is removing the disruptive student from their classroom (e.g. suspension or expulsion). There is a great need to study and understand the differences between school disciplinary practices and to allow research findings to guide the way in which discipline is administered. The current study examined a large database for the entire state of Louisiana to determine the relationship …
Multigrid Methods For Maxwell's Equations, Jintao Cui
Multigrid Methods For Maxwell's Equations, Jintao Cui
LSU Doctoral Dissertations
In this work we study finite element methods for two-dimensional Maxwell's equations and their solutions by multigrid algorithms. We begin with a brief survey of finite element methods for Maxwell's equations. Then we review the related fundamentals, such as Sobolev spaces, elliptic regularity results, graded meshes, finite element methods for second order problems, and multigrid algorithms. In Chapter 3, we study two types of nonconforming finite element methods on graded meshes for a two-dimensional curl-curl and grad-div problem that appears in electromagnetics. The first method is based on a discretization using weakly continuous P1 vector fields. The second method uses …
New Strategies For Phase Estimation In Quantum Optics, Yang Gao
New Strategies For Phase Estimation In Quantum Optics, Yang Gao
LSU Doctoral Dissertations
One important problem in quantum optics is to resolve an extremely small change of phase shift. The complementarity between photon number and phase sets an ultimate limit, the so-called Heisenberg limit, on the phase measurement sensitivity. The precise phase estimation has many technological applications, such as optical gyroscopes, gravitational wave detection, quantum imaging and sensing. In this thesis I show that the utilization of the parity measurement in the optical interferometry is actually applicable to a wide range of quantum entangled input states. Comparison of the performance of the various quantum states then can be made within such a unified …
Part I: Syntheses, Characterizations, And Investigations Of Molecular Micelles And Imidazolium-Based Ionic Liquids For Protein Separations In Electrophoresis Part Ii: Investigating The Mentoring Canon Through Exploration Of Thirty Years Of Mentoring By An Exemplar, Monica R. Sylvain
LSU Doctoral Dissertations
The research reported in this dissertation is presented in two parts. The first part is the Syntheses, Characterizations, and Investigations of Molecular Micelles and Imidazolium-Based Ionic Liquids for Protein Separations in Electrophoresis, and the second part is a case study entitled Investigating the Mentoring Canon through Exploration of Thirty Years of Mentoring by an Exemplar. Protein separations in the gel electrophoretic format are ubiquitous analyses used on a daily basis throughout biochemistry, analytical chemistry, and biotechnology. The goal of the research reported in the first part of this dissertation is to synthesize and characterize molecular micelles and ether-functionalized imidazolium-based ionic …
Particle Analysis In Infrared Laser Desorption And Ablation, Xing Fan
Particle Analysis In Infrared Laser Desorption And Ablation, Xing Fan
LSU Doctoral Dissertations
The fundamental physical processes of mid infrared laser ablation in the context of laser desorption mass spectrometry were investigated. Understanding the mechanisms of infrared laser desorption and ablation can lead to improvements in these techniques and expand their applications. Particles were generated from glycerol irradiated at atmospheric pressure using a tunable infrared laser at wavelengths between 2.6 and 3.8 µm. The wavelength dependence of size distributions of ablated particles was measured. The particle concentration roughly tracked the infrared absorption spectrum of glycerol and the mean particle size tracked the inverse of the IR absorption. A novel approach, post ablation particle …
Application-Level Optimization Of End-To-End Data Transfer Throughput, Esma Yildirim
Application-Level Optimization Of End-To-End Data Transfer Throughput, Esma Yildirim
LSU Doctoral Dissertations
For large-scale distributed applications, effective use of available network throughput and optimization of data transfer speed is crucial for end-to-end application performance. Today, many regional and national optical networking initiatives such as LONI, ESnet and Teragrid provide high speed network connectivity to their users. However, majority of the users fail to obtain even a fraction of the theoretical speeds promised by these networks due to issues such as sub-optimal protocol tuning, disk bottleneck on the sending and/or receiving ends, and processor limitations. This implies that having high speed networks in place is important but not sufficient for the improvement of …
Early Life History Dynamics Of The Fish Community In The Atchafalaya River Basin, B. Thorpe Halloran
Early Life History Dynamics Of The Fish Community In The Atchafalaya River Basin, B. Thorpe Halloran
LSU Doctoral Dissertations
Seasonal overbank flooding in systems like the Atchafalaya River Basin (ARB) provides the opportunity for fishes in the mainstem to access off-channel areas on the floodplain. Typically, newly inundated floodplain habitats allow adult fishes to add biomass, avoid predation, and potentially, to reproduce. However, in systems like the ARB, the timing, duration, and magnitude of flooding infrequently coincides with known reproductive periods of many fishes assumed to be floodplain-dependent. To quantify the level of floodplain-exploitative fish reproduction in the ARB, I collected larval and juvenile fish with a variety of sampling gear that allowed estimates in both ultra-shallow (< 2-m) and continuously-inundated habitats (headwater lakes, canals, and bayous). A suite of water quality parameters, river stage, flow, and hours of daylight were used to gauge the influence of environmental phenomena on age-0 abundance during both inundation and drawdown. The results of the 19-month study suggest that many taxa do not rely on the floodplain to ensure high survivorship. Interestingly, the reproductive ecologies of many ARB fishes appeared to be largely independent of widespread connectivity. Although an increasing hydrograph appeared to enhance reproductive output, the interannual timing and intensity of spawning showed limited variability. Larval densities were also contrasted with the microcrustacean zooplankton (copepods and cladocerans) population to assess if a potential food limitation existed in the weeks and months following hatching. During the study, increased zooplankter abundance was typically preceded by elevated river-floodplain connectivity. Conversely, as floodwaters receded during the summer, zooplankton abundance declined to lowest levels observed during the study. Overall, there was limited synchronous overlap between the hatchlings of most fish taxa and their zooplankter prey. This could have potentially resulted in starvation and reduced annual recruitment. Yet, my analysis of the factors that regulate larval fish abundance in the ARB suggest that the density of zooplankton was highly significant although high numbers of larvae and zooplankton rarely coincided. Finally, I compared the intraday (morning vs. afternoon) density and mean length of larval fish at fixed sample sites. The results suggest that once-daily ichthyoplankton collections may fail to provide accurate density and length measurements for young fish populations.