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Articles 31 - 54 of 54
Full-Text Articles in Physical Sciences and Mathematics
Region Of Smooth Functions For Positive Solutions To An Elliptic Biological Model, Joon Hyuk Kang, Timothy Robertson
Region Of Smooth Functions For Positive Solutions To An Elliptic Biological Model, Joon Hyuk Kang, Timothy Robertson
Faculty Publications
The non-existence and existence of the positive solution to the generalized elliptic model ∆u+g(u v) = 0 in Ω, ∆v+h(u, v) = 0 in Ω, u=v= 0 on∂Ω, were investigated.
A Nonlinear Splitting Algorithm For Systems Of Partial Differential Equations With Self-Diffusion, Matthew Beauregard, Joshua L. Padgett, Rana D. Parshad
A Nonlinear Splitting Algorithm For Systems Of Partial Differential Equations With Self-Diffusion, Matthew Beauregard, Joshua L. Padgett, Rana D. Parshad
Faculty Publications
Systems of reaction-diffusion equations are commonly used in biological models of food chains. The populations and their complicated interactions present numerous challenges in theory and in numerical approximation. In particular, self-diffusion is a nonlinear term that models overcrowding of a particular species. The nonlinearity complicates attempts to construct efficient and accurate numerical approximations of the underlying systems of equations. In this paper, a new nonlinear splitting algorithm is designed for a partial differential equation that incorporates self diffusion. We present a general model that incorporates self-diffusion and develop a numerical approximation. The numerical analysis of the approximation provides criteria for …
Biological Control Via "Ecological" Damping: An Approach That Attenuates Non-Target Effects, Rana D. Parshad, Kelly Black, Emmanuel Quansah, Matthew Beauregard
Biological Control Via "Ecological" Damping: An Approach That Attenuates Non-Target Effects, Rana D. Parshad, Kelly Black, Emmanuel Quansah, Matthew Beauregard
Faculty Publications
In this work we develop and analyze a mathematical model of biological control to prevent or attenuate the explosive increase of an invasive species population in a three-species food chain. We allow for finite time blowup in the model as a mathematical construct to mimic the explosive increase in population, enabling the species to reach “disastrous” levels, in a finite time. We next propose various controls to drive down the invasive population growth and, in certain cases, eliminate blow-up. The controls avoid chemical treatments and/or natural enemy introduction, thus eliminating various non-target effects associated with such classical methods. We refer …
Investr: An R Package For Inverse Estimation, Brandon M. Greenwell, Christine M. Schubert Kabban
Investr: An R Package For Inverse Estimation, Brandon M. Greenwell, Christine M. Schubert Kabban
Faculty Publications
Inverse estimation is a classical and well-known problem in regression. In simple terms, it involves the use of an observed value of the response to make inference on the corresponding unknown value of the explanatory variable. To our knowledge, however, statistical software is somewhat lacking the capabilities for analyzing these types of problems. In this paper, we introduce investr (which stands for inverse estimation in R), a package for solving inverse estimation problems in both linear and nonlinear regression models.
Sixteen Years Of Collaborative Learning Through Active Sense-Making In Physics (Clasp) At Uc Davis, Wendell Potter, David Webb, Cassandra Paul, Emily West, Mark Bowen, Brenda Weiss, Lawrence Coleman, Charles De Leone
Sixteen Years Of Collaborative Learning Through Active Sense-Making In Physics (Clasp) At Uc Davis, Wendell Potter, David Webb, Cassandra Paul, Emily West, Mark Bowen, Brenda Weiss, Lawrence Coleman, Charles De Leone
Faculty Publications
This paper describes our large reformed introductory physics course at UC Davis, which bioscience students have been taking since 1996. The central feature of this course is a focus on sense-making by the students during the five hours per week discussion/labs in which the students take part in activities emphasizing peer-peer discussions, argumentation, and presentations of ideas. The course differs in many fundamental ways from traditionally taught introductory physics courses. After discussing the unique features of CLASP and its implementation at UC Davis, various student outcome measures are presented showing increased performance by students who took the CLASP course compared …
Winter Movements Of Louisiana Pine Snakes (Pituophis Ruthveni) In Texas And Louisiana, Josh B. Pierce, D. Craig Rudolph, Shirley J. Burgdorf, Richard R. Schaefer, Richard N. Conner, John G. Himes, C. Mike Duran, Laurence M. Hardy, Robert R. Fleet
Winter Movements Of Louisiana Pine Snakes (Pituophis Ruthveni) In Texas And Louisiana, Josh B. Pierce, D. Craig Rudolph, Shirley J. Burgdorf, Richard R. Schaefer, Richard N. Conner, John G. Himes, C. Mike Duran, Laurence M. Hardy, Robert R. Fleet
Faculty Publications
Despite concerns that the Louisiana Pine Snake (Pituophis ruthveni) has been extirpated from large portions of its historic range, only a limited number of studies on their movement patterns have been published. Winter movement patterns are of particular interest since it has been hypothesized that impacts of management practices would be reduced during the winter. Using radiotelemetry, we determined winter movement patterns of Louisiana Pine Snakes (11 males, 8 females) in 5 study areas (2 in Louisiana and 3 in Texas). Movements during winter (November–February) were greatly curtailed compared to the remainder of the year; however, snakes occasionally undertook substantial …
Preservation Of A Convergence Of A Sequence To A Set, Akira Iwasa, Masaru Kada, Shizuo Kamo
Preservation Of A Convergence Of A Sequence To A Set, Akira Iwasa, Masaru Kada, Shizuo Kamo
Faculty Publications
We say that a sequence of points converges to a set if every open set containing the set contains all but finitely many terms of the sequence. We investigate preservation of convergence of a sequence to a set in forcing extensions.
Low Mach Number Fluctuating Hydrodynamics Of Diffusively Mixing Fluids, Aleksandar Donev, Andy J. Nonaka, Yifei Sun, Thomas Fai, Alejandro Garcia, John B. Bell
Low Mach Number Fluctuating Hydrodynamics Of Diffusively Mixing Fluids, Aleksandar Donev, Andy J. Nonaka, Yifei Sun, Thomas Fai, Alejandro Garcia, John B. Bell
Faculty Publications
We formulate low Mach number fluctuating hydrodynamic equations appropriate for modeling diffusive mixing in isothermal mixtures of fluids with different density and transport coefficients. These equations eliminate the fast isentropic fluctuations in pressure associated with the propagation of sound waves by replacing the equation of state with a local thermodynamic constraint. We demonstrate that the low Mach number model preserves the spatio-temporal spectrum of the slower diffusive fluctuations. We develop a strictly conservative finite-volume spatial discretization of the low Mach number fluctuating equations in both two and three dimensions. We construct several explicit Runge-Kutta temporal integrators that strictly maintain the …
Positive Equilibrium Solutions To General Population Model, Joon Hyuk Kang
Positive Equilibrium Solutions To General Population Model, Joon Hyuk Kang
Faculty Publications
In this paper, we investigate conditions for the existence of positive solution to the following general elliptic system with various growth conditions: {Δu + u(a + g(u, v)) = 0 Δv + v(d + h(u, v)) = 0 u|∂ω=v|∂ω=0 in ω. Our arguments mainly rely on super-sub solutions, maximum principles, spectrum estimates, and some detailed properties for the solution of logistic equations. © 2013 Academic Publications, Ltd.
Independent Dominating Sets In Triangle-Free Graphs, Wayne Goddard, Jeremy Lyle
Independent Dominating Sets In Triangle-Free Graphs, Wayne Goddard, Jeremy Lyle
Faculty Publications
The independent domination number of a graph is the smallest cardinality of an independent set that dominates the graph. In this paper we consider the independent domination number of triangle-free graphs. We improve several of the known bounds as a function of the order and minimum degree, thereby answering conjectures of Haviland.
Cooper’S Hawk Nest Site Characteristics In The Pineywoods Region, Richard R. Schaefer, D. Craig Rudolph, Josh B. Pierce, Jesse F. Fagan
Cooper’S Hawk Nest Site Characteristics In The Pineywoods Region, Richard R. Schaefer, D. Craig Rudolph, Josh B. Pierce, Jesse F. Fagan
Faculty Publications
Early accounts describe the Cooper’s Hawk (Accipiter cooperi) as a species in decline in much of North America during the early twentieth century (Bent 1937), particularly when in close proximity to humans (Eaton 1914). This decreasing population trend continued to be recognized later in the century in both Texas (Oberholser 1974) and Louisiana (Lowery 1974). Shooting and trapping during the first half of the 1900s, and pesticide use (especially DDT) after World War II are suggested as primary causes of the decline (Henny and Wight 1972, Bednarz et al. 1990). The Migratory Bird Treaty Act of 1972 and the ban …
A Sequel To “A Space Topologized By Functions From Omega To Omega”, Tetsuya Ishiu, Akira Iwasa
A Sequel To “A Space Topologized By Functions From Omega To Omega”, Tetsuya Ishiu, Akira Iwasa
Faculty Publications
We consider a topological space ⟨𝑋, 𝜏 (ℱ)⟩, where 𝑋 = {𝑝 ∗} ∪ [𝜔 Å~ 𝜔] and ℱ ⊆ 𝜔𝜔. Each point in 𝜔 Å~ 𝜔 is isolated and a neighborhood of 𝑝∗ has the form {𝑝∗}∪{⟨𝑖, 𝑗⟩ : 𝑖 ≥ 𝑛, 𝑗 ≥ 𝑓(𝑖)} for some 𝑛 ∈ 𝜔 and 𝑓 ∈ ℱ. We show that there are subsets ℱ and 𝒢 of 𝜔𝜔 such that ℱ is not bounded, 𝒢 is bounded, yet ⟨𝑋, 𝜏 (ℱ)⟩ and ⟨𝑋, 𝜏 (𝒢)⟩ are homeomorphic. This answers a question of the second author posed in A space topologized by functions …
On The Accuracy Of Explicit Finite-Volume Schemes For Fluctuating Hydrodynamics, Aleksandar Donev, Eric Vanden-Eijnden, Alejandro Garcia, John B. Bell
On The Accuracy Of Explicit Finite-Volume Schemes For Fluctuating Hydrodynamics, Aleksandar Donev, Eric Vanden-Eijnden, Alejandro Garcia, John B. Bell
Faculty Publications
This paper describes the development and analysis of finite-volume methods for the Landau–Lifshitz Navier–Stokes (LLNS) equations and related stochastic partial differential equations in fluid dynamics. The LLNS equations incorporate thermal fluctuations into macroscopic hydrodynamics by the addition of white noise fluxes whose magnitudes are set by a fluctuation-dissipation relation. Originally derived for equilibrium fluctuations, the LLNS equations have also been shown to be accurate for nonequilibrium systems. Previous studies of numerical methods for the LLNS equations focused primarily on measuring variances and correlations computed at equilibrium and for selected nonequilibrium flows. In this paper, we introduce a more systematic approach …
A Space Topologized By Functions From Omega To Omega, Akira Iwasa
A Space Topologized By Functions From Omega To Omega, Akira Iwasa
Faculty Publications
No abstract provided.
Extending The Support Theorem To Infinite Dimensions, Jeremy J. Becnel
Extending The Support Theorem To Infinite Dimensions, Jeremy J. Becnel
Faculty Publications
The Radon transform is one of the most useful and applicable tools in functional analysis. First constructed by John Radon in 1917 [9] it has now been adapted to several settings. One of the principle theorems involving the Radon transform is the Support Theorem. In this paper, we discuss how the Radon transform can be constructed in the white noise setting. We also develop a Support Theorem in this setting.
Habitat Selection By Anolis Carolinensis (Green Anole) In Open Pine Forests In Eastern Texas, Richard R. Schaefer, Robert R. Fleet, D. Craig Rudolph, Nancy E. Koerth
Habitat Selection By Anolis Carolinensis (Green Anole) In Open Pine Forests In Eastern Texas, Richard R. Schaefer, Robert R. Fleet, D. Craig Rudolph, Nancy E. Koerth
Faculty Publications
We initiated a mark-recapture study to determine the effects of shrub density on Anolis carolinensis (Green Anole) populations. Green Anole perch site, shrub species, and shrub volume preferences were also examined. We established two study plots of different shrub densities in open pine forests on the Angelina National Forest in eastern Texas. In late spring, the Green Anole population at the higher shrub-density plot was estimated to be 16 times greater than the population at the lower shrub-density plot. Green Anoles most commonly perched on live shrubs, but exhibited very little preference or avoidance of any particular species of live …
Use Of Trees By The Texas Ratsnake (Elaphe Obsoleta) In Eastern Texas, Josh B. Pierce, Robert R. Fleet, Lance Mcbrayer, D. Craig Rudolph
Use Of Trees By The Texas Ratsnake (Elaphe Obsoleta) In Eastern Texas, Josh B. Pierce, Robert R. Fleet, Lance Mcbrayer, D. Craig Rudolph
Faculty Publications
We present information on the use of trees by Elaphe obsoleta (Texas Ratsnake) in a mesic pine-hardwood forest in eastern Texas. Using radiotelemetry, seven snakes (3 females, 4 males) were relocated a total of 363 times from April 2004 to May 2005, resulting in 201 unique locations. Snakes selected trees containing cavities and used hardwoods and snags for a combined 95% of arboreal locations. Texas Ratsnake arboreal activity peaked during July and August, well after the peak of avian breeding activity, suggesting arboreal activity involves factors other than avian predation.
Spatial Ecology Of The Coachwhip, Masticophis Flagellum (Squamata: Colubridae), In Eastern Texas, Richard W. Johnson, Robert R. Fleet, Michael B. Keck, D. Craig Rudolph
Spatial Ecology Of The Coachwhip, Masticophis Flagellum (Squamata: Colubridae), In Eastern Texas, Richard W. Johnson, Robert R. Fleet, Michael B. Keck, D. Craig Rudolph
Faculty Publications
We radio-tracked nine Masticophis flagellum (Coachwhips) to determine home range, habitat use, and movements in eastern Texas from April to October 2000. Home ranges of Coachwhips contained more oak savanna macrohabitat than early-successional pine plantation or forested seep, based on the availability of these three macrohabitats in the study area. Likewise, within their individual home ranges, Coachwhips used oak savanna more than the other two macrohabitats, based on availability. An analysis of microhabitat use revealed that, relative to random sites within their home range, Coachwhips were found at sites with fewer pine trees and more herbaceous vegetation taller than 30 …
Covering Properties And Cohen Forcing, Akira Iwasa
Covering Properties And Cohen Forcing, Akira Iwasa
Faculty Publications
We will show that adding Cohen reals preserves the covering property that every open cover has a σ-P Q refinement and deduce that adding Cohen reals preserves covering properties such as paracompactness, subparacompactness and screenability.
Multiple Mixed-Type Attractors In A Competition Model, J. M. Cushing, Shandelle M. Henson, Chantel C. Blackburn
Multiple Mixed-Type Attractors In A Competition Model, J. M. Cushing, Shandelle M. Henson, Chantel C. Blackburn
Faculty Publications
We show that a discrete-time, two-species competition model with Ricker (exponential) nonlinearities can exhibit multiple mixed-type attractors. By this is meant dynamic scenarios in which there are simultaneously present both coexistence attractors (in which both species are present) and exclusion attractors (in which one species is absent). Recent studies have investigated the inclusion of life-cycle stages in competition models as a casual mechanism for the existence of these kinds of multiple attractors. In this paper we investigate the role of nonlinearities in competition models without life-cycle stages. © 2007 Taylor & Francis Group, LLC.
Subspaces Of Ωω That Are Paracompact In Some Forcing Extension, Akira Iwasa
Subspaces Of Ωω That Are Paracompact In Some Forcing Extension, Akira Iwasa
Faculty Publications
We discuss when a subspace of ωω is paracompact in some forcing extension.
Estimating Hydrodynamic Quantities In The Presence Of Microscopic Fluctuations, Alejandro Garcia
Estimating Hydrodynamic Quantities In The Presence Of Microscopic Fluctuations, Alejandro Garcia
Faculty Publications
This paper discusses the evaluation of hydrodynamic variables in the presence of spontaneous fluctuations, such as in molecular simulations of fluid flows. The principal point is that hydrodynamic variables such as fluid velocity and temperature must be defined in terms of mechanical variables such as momentum and energy density). Because these relations are nonlinear and because fluctuations of mechanical variables are correlated, care must be taken to avoid introducing a bias when evaluating means, variances, and correlations of hydrodynamic variables. The unbiased estimates are formulated; some alternative, incorrect approaches are presented as cautionary warnings. The expressions are verified by numerical …
Diel Activity Patterns Of The Louisiana Pine Snakes (Pituophis Ruthveni) In Eastern Texas, Marc J. Ealy, Robert R. Fleet, D. Craig Rudolph
Diel Activity Patterns Of The Louisiana Pine Snakes (Pituophis Ruthveni) In Eastern Texas, Marc J. Ealy, Robert R. Fleet, D. Craig Rudolph
Faculty Publications
This study examined the diel activity patterns of six Louisiana pine snakes in eastern Texas using radio-telemetry. snakes were monitored for 44 days on two study areas from May to October 1996. Louisana pine snakes were primarily diurnal with moderate crepuscular activity, spending the night within pocket gopher burrows or inactive on the surface. During daylight hours, snakes spent approximately 59% of their time underground within gopher burrows, burned out/rotten stumps, or nine-branded armadillo (Dasypus novemcinctus) burrows. Remaining time was spent on the surface either close to subteranean refuge, or in long distance movements that generally terminet at …
The Laws Of Complexity & The Complexity Of Laws: The Implications Of Computational Complexity Theory For The Law, Eric Kades
Faculty Publications
No abstract provided.