Physical Sciences and Mathematics Commons^™

Determination Of Extracellular Molecules Produced By Vibrio Harveyi Using Ms/Ms, Jose G. Roble

FIU Electronic Theses and Dissertations

Quorum sensing (QS) is a process that allows bacteria to sense the population density of cells around them by communicating with each other via autoinducer molecules. This cross-communication is crucial in the regulation of bacterial processes such as bioluminescence, virulence, and biofilm formation. Previous research by Milburn and Makemson on Vibrio harveyi suggested that in addition of the known biosynthesis of three well-characterized autoinducers, dozens of unknown molecules are also produced and released to the environment by V. harveyi. This study was performed using electrospray tandem mass spectrometry with the purpose of detection and characterization of the extracellular molecules …

Complementary Mass Spectrometry Methods For Characterizing Protein Folding, Structure, And Dynamics, Siavash Vahidi

Electronic Thesis and Dissertation Repository

Proteins are involved in virtually every biochemical process. A comprehensive characterization of factors that govern protein function is essential for understanding the biomedical aspects of human health. This dissertation aims to develop complementary mass spectrometry-based methods and apply them to solve problems pertaining to the area of protein structure, folding and dynamics.

‎Chapter 1 uses fast photochemical oxidation of proteins (FPOP) to characterize partially disordered conformers populated under semi-denaturing conditions. In FPOP, ·OH generated by laser photolysis of H₂O₂ introduces oxidative modifications at solvent accessible side chains. By contrast, buried sites are protected from radical attack. Using …

Influence Of Biofield Treatment On Physicochemical Properties Of Hydroxyethyl Cellulose And Hydroxypropyl Cellulose, Mahendra Kumar Trivedi, Gopal Nayak, Shrikant Patil, Rama Mohan Tallapragada, Rakesh K. Mishra

Mahendra Kumar Trivedi

Measuring Infrared Surface Brightness Fluctuation Distances With Hst Wfc3: Calibration And Advice, Joseph Jensen

Joseph Jensen

Poly(N-Isopropylacrylamide) Hydrogels For Storage And Delivery Of Reagents To Paper-Based Analytical Devices, Haydn T. Mitchell, Spencer Schultz, Philip Costanzo, Andres W. Martinez

Chemistry and Biochemistry

The thermally responsive hydrogel N,N'-methylenebisacrylamide-cross-linked poly(N-isopropylacrylamide) (PNIPAM) was developed and evaluated as a reagent storage and delivery system for microfluidic paper-based analytical devices (microPADs). PNIPAM was shown to successfully deliver multiple solutions to microPADs in specific sequences or simultaneously in laminar-flow configuration and was found to be suitable for delivering four classes of reagents to the devices: Small molecules, enzymes, antibodies and DNA. PNIPAM was also able to successfully deliver a series of standard glucose solutions to microPADs equipped to perform a colorimetric glucose assay. The results of these tests were used to produce an external calibration …

Urban Stream Burial Increases Watershed-Scale Nitrate Export, Jake J. Beaulieu, Heather E. Golden, Christopher D. Knightes, Paul M. Mayer, Sujay S. Kaushal, Michael J. Pennino, Clay P. Arango, David A. Balz, Colleen M. Elonen, Ken M. Fritz, Brian H. Hill

All Faculty Scholarship for the College of the Sciences

Nitrogen (N) uptake in streams is an important ecosystem service that reduces nutrient loading to downstream ecosystems. Here we synthesize studies that investigated the effects of urban stream burial on N-uptake in two metropolitan areas and use simulation modeling to scale our measurements to the broader watershed scale. We report that nitrate travels on average 18 times farther downstream in buried than in open streams before being removed from the water column, indicating that burial substantially reduces N uptake in streams. Simulation modeling suggests that as burial expands throughout a river network, N uptake rates increase in the remaining open …

Impacts Of Community-Based Natural Resource Management On Wealth, Food Security And Child Health In Tanzania, Sharon Pailler, Robin Naidoo, Neil D. Burgess, Olivia E. Freeman, Brendan Fisher

Rubenstein School of Environment and Natural Resources Faculty Publications

Community-based natural resource management (CBNRM) is a major global strategy for enhancing conservation outcomes while also seeking to improve rural livelihoods; however, little evidence of socioeconomic outcomes exists. We present a national-level analysis that empirically estimates socioeconomic impacts of CBNRM across Tanzania, while systematically controlling for potential sources of bias. Specifically, we apply a difference-indifferences model to national-scale, cross-sectional data to estimate the impact of three different CBNRM governance regimes on wealth, food security and child health, considering differential impacts of CBNRM on wealthy and poor populations. We also explore whether or not longer-standing CBNRM efforts provide more benefits than …

Pglr-Sas Data, Joseph M. Hilbe

Joseph M Hilbe

SAS data files for Practical Guide to Logistic Regression

R Code For Practical Guide To Logistic Regression, Joseph M. Hilbe

Joseph M Hilbe

R code for Practical Guide to Logistic Regression

Pglr-Stata Data Files, Joseph M. Hilbe

Joseph M Hilbe

Stata data files for Practical Guide to Logistic Regression

Sas Code Only For Practical Guide To Logistic Regression, Joseph M. Hilbe

Joseph M Hilbe

SAS code-only for Practical Guide to Logistic Regression

Sas Code & Output For Practical Guide To Logistic Regression, Joseph M. Hilbe

Joseph M Hilbe

SAS code for Practical Guide to Logistic Regression

High Precision Optical Cavity Length And Width Measurements Using Double Modulation, A. Staley, D. Hoak, A. Effler, K. Izumi, S. Dwyer, K. Kawabe, E. J. King, Malik Rakhmanov, R. L. Savage, D. Sigg

Physics and Astronomy Faculty Publications and Presentations

We use doubly phase modulated light to measure both the length and the linewidth of an optical resonator with high precision. The first modulation is at RF frequencies and is set near a multiple of the free spectral range, whereas the second modulation is at audio frequencies to eliminate offset errors at DC. The light in transmission or in reflection of the optical resonator is demodulated while sweeping the RF frequency over the optical resonance. We derive expressions for the demodulated power in transmission, and show that the zero crossings of the demodulated signal in transmission serve as a precise …

Brown Carbon Aerosol In The North American Continental Troposphere: Sources, Abundance, And Radiative Forcing, J. Liu, Eric Scheuer, Jack E. Dibb, G S. Diskin, L D. Ziemba, K L. Thornhill, B E. Anderson, A Whisthaler, T Mikoviny, J J. Devi, M Bergin, A E. Perring, M Z. Markovic, J P. Schwarz, P Campuzano-Jost, D A. Day, J L. Jimenez, R J. Weber

Earth Sciences

Chemical components of organic aerosol (OA) selectively absorb light at short wavelengths. In this study, the prevalence, sources, and optical importance of this so called brown carbon (BrC) aerosol component are investigated throughout the North American continental tropospheric column during a summer of extensive biomass burning. Spectrophotometric absorption measurements on extracts of bulk aerosol samples collected from an aircraft over the central USA were analyzed to directly quantify BrC abundance. BrC was found to be prevalent throughout the 1 to 12 km altitude measurement range, with dramatic enhancements in biomass-burning plumes. BrC to black carbon (BC) ratios, under background tropospheric …

Transition Metal-Olefin Bonding Interactions: A Density Functional Theory Study [ M ( Co ) X ( Æ? 2-C 2 H 3-C 6 H 4-Y) ], Michael John Berninger

Theses and Dissertations

Metal-olefin equilibrium geometries, bond formation energies (Î?E), enthalpies (Î?H), and free energies (Î?G) for a select series of transition (M = Ni, Fe, Cr, Mo and W) metal-olefin carbonyl complexes [M(CO)x(Æ?2-C2H3-C6H4-Y)] have been calculated and compared using density functional theory (DFT), with the BP86 functional under standard state conditions (1 atm, 298.15 K) for the general gas phase formation reaction:

M(CO)x + (C2H3-C6H4-Y) â?? [M(CO)x(Æ?2-C2H3-C6H4-Y)] (1)

Y = NO2, CN, COOH, H, OH, NH2, N(CH3)2

In regards to the electronic modification of the substituent (Y) on styrene at the para position, this study quantitatively investigated the effect of electron-withdrawing and …

Unimolecular Decomposition Of Formic And Acetic Acids: A Shock Tube/Laser Absorption Study, A. Elwardany, E. F. Nasir, Et. Es-Sebbar, A. Farooq

Dr. Et-touhami Es-sebbar

The thermal decomposition of formic acid (HCOOH) and acetic acid (CH3COOH), two carboxylic acids which play an important role in oxygenate combustion chemistry, were investigated behind reflected shock waves using laser absorption. The rate constants of the primary decomposition pathways of these acids: The thermal decomposition of formic acid (HCOOH) and acetic acid (CH3COOH), two carboxylic acids which play an important role in oxygenate combustion chemistry, were investigated behind reflected shock waves using laser absorption. The rate constants of the primary decomposition pathways of these acids: HCOOH→CO+H2O (R1) HCOOH→CO2+H2 (R2) CH3COOH→CH4+CO2 (R3) CH3COOH→CH2CO+H2O (R4) were measured using simultaneous infrared laser …

Global Dynamics Of Triangular Maps, Eduardo Balreira, Saber Elaydi, Rafael Luis

Saber Elaydi

We consider continuous triangular maps on IN, where I is a compact interval in the Euclidean space R. We show, under some conditions, that the orbit of every point in a triangular map converges to a fixed point if and only if there is no periodic orbit of prime period two. As a consequence we obtain a result on global stability, namely, if there are no periodic orbits of prime period 2 and the triangular map has a unique fixed point, then the fixed point is globally asymptotically stable. We also discuss examples and applications of our results to competition …

Local Stability Implies Global Stability For The Planar Ricker Competition Model, Eduardo Balreira, Saber Elaydi, Rafael Luis

Saber Elaydi

Under certain analytic and geometric assumptions we show that local stability of the coexistence (positive) fixed point of the planar Ricker competition model implies global stability with respect to the interior of the positive quadrant. This result is a confluence of ideas from Dynamical Systems, Geometry, and Topology that provides a framework to the study of global stability for other planar competition models.

Existence And Stability Of Periodic Orbits Of Periodic Difference Equations With Delays, Ziyad Alsharawi, James Angelos, Saber Elaydi

Saber Elaydi

In this paper, we investigate the existence and stability of periodic orbits of the p-periodic difference equation with delays xn = f(n−1, xn−k). We show that the periodic orbits of this equation depend on the periodic orbits of p autonomous equations when p divides k. When p is not a divisor of k, the periodic orbits depend on the periodic orbits of gcd(p, k) nonautonomous p gcd(p,k) - periodic difference equations. We give formulas for calculating the number of different periodic orbits under certain conditions. In addition, when p and k are relatively prime integers, we introduce what we call …

Population Models In Almost Periodic Environments, Toka Diagana, Saber Elaydi, Abdul-Aziz Yakubu

Saber Elaydi

We establish the basic theory of almost periodic sequences on Z+. Dichotomy techniques are then utilized to find sufficient conditions for the existence of a globally attracting almost periodic solution of a semilinear system of difference equations. These existence results are, subsequently, applied to discretely reproducing populations with and without overlapping generations. Furthermore, we access evidence for attenuance and resonance in almost periodically forced population models.

Stability And Asymptoticity Of Volterra Difference Equations: A Progress Report, Saber Elaydi

Saber Elaydi

We survey some of the fundamental results on the stability and asymptoticity of linear Volterra difference equations. The method of Z-transform is heavily utilized in equations of convolution type. An example is given to show that uniform asymptotic stability does not necessarily imply exponential stabilty. It is shown that the two notions are equivalent if the kernel decays exponentially. For equations of nonconvolution type, Liapunov functions are used to find explicit criteria for stability. Moreover, the resolvent matrix is defined to produce a variation of constants formula. The study of asymptotic equivalence for difference equations with infinite delay is carried …

On The Asymptotic Stability Of Linear Volterra Difference Equations Of Convolution Type, Saber Elaydi, E Messina, A Vecchio

Saber Elaydi

No abstract provided.

On The Stochastic Beverton-Holt Equation With Survival Rates, Paul H. Bezandry, Toka Diagana, Saber Elaydi

Saber Elaydi

The paper studies a Beverton-Holt difference equation, in which both the recruitment function and the survival rate vary randomly. It is then shown that there is a unique invariant density, which is asymptotically stable. Moreover, a basic theory for random mean almost periodic sequence on Z+ is given. Then, some suffcient conditions for the existence of a mean almost periodic solution to the stochastic Beverton-Holt equation are given.

An Economical Model With Allee Effect, Rafael Luis, Saber Elaydi, Henrique Oliveira

Saber Elaydi

The Marx model for the profit rate r depending on the exploitation rate e and on the organic composition of the capital k is studied using a dynamical approach. Supposing both e(t) and k(t) are continuous functions of time we derive a law for r(t) in the long term. Depending upon the hypothesis set on the growth of k(t) and e(t) in the long term, r(t) can fall to zero or remain constant. This last case contradicts the classical hypothesis of Marx stating that the profit rate must decrease in the long term. Introducing a discrete dynamical system in the …

Population Models With Allee Effect: A New Model, Saber Elaydi, Robert J. Sacker

Saber Elaydi

In this paper we develop several mathematical models of Allee effects. We start by defining the Allee effect as a phenomenon in which individual fitness increases with increasing density. Based on this biological assumption, we develop several fitness functions that produce corresponding models with Allee effects. In particular, a rational fitness function yields a new mathematical model that is our focus of study. Then we study the dynamics of 2-periodic systems with Allee effects and show the existence of an asymptotically stable 2-periodic carrying capacity.

Non-Autonomous Periodic Systems With Allee Effects, Rafael Luis, Saber Elaydi, Henrique Oliveira

Saber Elaydi

A new class of maps called unimodal Allee maps are introduced. Such maps arise in the study of population dynamics in which the population goes extinct if its size falls below a threshold value. A unimodal Allee map is thus a unimodal map with tree fixed points, a zero fixed point, a small positive fixed point, called threshold point, and a bigger positive fixed point, called the carrying capacity. In this paper the properties and stability of the three fixed points are studied in the setting of nonautonomous periodic dynamical systems or difference equations. Finally we investigate the bifurcation of …

Towards A Theory Of Periodic Difference Equations And Its Application To Population Dynamics, Saber Elaydi, Rafael Luis, Henrique Oliveira

Saber Elaydi

This survey contains the most updated results on the dynamics of periodic difference equations or discrete dynamical systems this time. Our focus will be on stability theory, bifurcation theory, and on the effect of periodic forcing on the welfare of the population (attenuance versus resonance). Moreover, the survey alludes to two more types of dynamical systems, namely, almost periodic difference equations and stochastic di®erence equations.

Bifurcation And Invariant Manifolds Of The Logistic Competition Model, Malgorzata Guzowska, Rafael Luis, Saber Elaydi

Saber Elaydi

In this paper we study a new logistic competition model. We will investigate stability and bifurcation of the model. In particular, we compute the invariant manifolds, including the important center manifolds, and study their bifurcation. Saddle-node and period doubling bifurcation route to chaos is exhibited via numerical simulations.

General Allee Effect In Two-Species Population Biology, G Livadiotis, Saber Elaydi

Saber Elaydi

The main objective of this work is to present a general framework for the notion of the strong Allee effect in population models, including competition, mutualistic, and predator–prey models. The study is restricted to the strong Allee effect caused by an inter-specific interaction. The main feature of the strong Allee effect is that the extinction equilibrium is an attractor. We show how a ‘phase space core’ of three or four equilibria is sufficient to describe the essential dynamics of the interaction between two species that are prone to the Allee effect. We will introduce the notion of semistability in planar …

Technology Professional Development: Long-Term Effects On Teacher Self-Efficacy, George Watson

George R Watson

The West Virginia K-12 RuralNet Project was an NSF funded program to train inservice teachers on integrating the Internet into science and mathematics curriculum. The program involved training inservice teachers through an intensive summer workshop and supplemental online courses. This study examines the effects of the project on the long-term self-efficacy of inservice teachers and their use of the Internet in the classroom. The specific research questions addressed are: Do professional development programs affect the long-term self-efficacy of inservice teachers? Did the addition of online courses and follow-up to the program affect self-efficacy levels? Finally, do certain external factors, specifically …