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Full-Text Articles in Life Sciences

Ecosystem Metabolism In A Subtropical Seagrass-Dominated Lagoon, Susan Ziegler, Ronald Benner Nov 1998

Ecosystem Metabolism In A Subtropical Seagrass-Dominated Lagoon, Susan Ziegler, Ronald Benner

Faculty Publications

Measurements of ecosystem gross primary production (GPP) and respiration (R) were made for 2 to 3 consecutive days on 10 occasions from February 1996 through June 1997 in the seagrass-dominated Laguna Madre (Texas, USA). Ecosystem GPP and R were quantified using 3 independent measurements including the open-water technique using dissolved oxygen (DO) and dissolved inorganic carbon (DIC) and the summation of discrete measurements of the water column and benthos. Diel curves of DIC were often influenced by water movement while the impact of water movement on DO was not apparent. This was attributed to the longer turnover time of DIC ...


Monte Carlo Simulation Of An Ion-Dipole Mixture As A Model Of An Electrical Double Layer, Douglas Henderson, Dezso Boda, Kwong-Yu Chan Nov 1998

Monte Carlo Simulation Of An Ion-Dipole Mixture As A Model Of An Electrical Double Layer, Douglas Henderson, Dezso Boda, Kwong-Yu Chan

Faculty Publications

Canonical Monte Carlo simulations were performed for a nonprimitive model of an electrical double layer. The ions and the solvent molecules are modeled as charged and dipolar hard spheres, respectively, while the electrode as a hard, impenetrable wall carrying uniform surface charge. We found that the ion-dipole model gives a reasonable description of the double layer for partially charged ions with small to moderate dipole moments, or equivalently for an "effective" dielectric constant. Density, polarization and mean electrostatic potential profiles are reported. Strong layering structure, and at higher charges, charge inversion in the second layer were found. With appropriate choices ...


Optimized Boundary Conditions And Data Assimilation With Application To The M-2 Tide In The Yellow Sea, Igor Shulman, James K. Lewis, Alan F. Blumberg, B. Nicholas Kim Aug 1998

Optimized Boundary Conditions And Data Assimilation With Application To The M-2 Tide In The Yellow Sea, Igor Shulman, James K. Lewis, Alan F. Blumberg, B. Nicholas Kim

Faculty Publications

An optimization approach is derived for assimilating tidal height information along the open boundaries of a numerical model. The approach is then extended so that similar data along transects inside a model domain can also be optimally assimilated. To test the application of such an optimized methodology, M-2 tidal simulations were conducted with a numerical ocean model of the Yellow Sea, an area with a strong tidal influence. The use of the optimized open boundary conditions and internal data assimilation leads to a significant improvement of the predictive skill of the model. Average errors can be reduced by up to ...


Solute-Solvent Pair Distribution Functions In Highly Asymmetric Additive Hard Sphere Mixtures, Douglas Henderson, Kwong-Yu Chan Jun 1998

Solute-Solvent Pair Distribution Functions In Highly Asymmetric Additive Hard Sphere Mixtures, Douglas Henderson, Kwong-Yu Chan

Faculty Publications

Contact values for the solute-solvent pair distribution function in an additive hard sphere mixture, as computed from the Henderson-Chan (HC) formulas, are compared with the recent Monte Carlo (MC) data and formula of Matyushov and Ladanyi (ML) [J. Chem. Phys. 107, 5815 (1997)]. The agreement is found to be excellent. The negative finding of ML is due to a misprint in one of the HC publications. We find the HC formula to be superior to the ML formula when compared to our MC data [Mol. Phys. 91, 1137 (1997)] for the case where the ratio of diameters is large and ...


Ecosystem Responses To Internal And Watershed Organic Matter Loading: Consequences For Hypoxia In The Eutrophying Neuse River Estuary, North Carolina, Usa, Hans W. Paerl, James L. Pinckney, John M. Fear, Benjamin L. Peierls May 1998

Ecosystem Responses To Internal And Watershed Organic Matter Loading: Consequences For Hypoxia In The Eutrophying Neuse River Estuary, North Carolina, Usa, Hans W. Paerl, James L. Pinckney, John M. Fear, Benjamin L. Peierls

Faculty Publications

The contrasting impacts of externally supplied (runoff) and internally generated (nutrient stimulated phytoplankton blooms) organic matter on oxygen (02) depletion were examined and evaluated in the eutrophic, salinity-stratified Neuse River Estuary, North Carolina, USA. This nitrogen (N)- limited estuary is experiencing increasing anthropogenic N loading from expanding urban, agricultural and industrial development in its watershed. Resultant algal blooms, which provided organic matter loads capable of causing extensive low 02 (hypoxic) and depleted 02 (anoxic) conditions, have induced widespread mortality of resident fin- and shellfish. Phytoplankton blooms followed periods of elevated N loading, except during extremely high runoff ...


On The Utility And Disutility Of Jebar, Mark A. Cane, Vladimir M. Kamenkovich, Alexander Krupitsky Mar 1998

On The Utility And Disutility Of Jebar, Mark A. Cane, Vladimir M. Kamenkovich, Alexander Krupitsky

Faculty Publications

The usefulness of the concept of JEBAR, the joint effect of baroclinicity and relief, in large-scale ocean dynamics is critically analyzed. The authors address two questions. Does the JEBAR term properly characterize the joint impact of stratification and bottom topography on the ocean circulation? Do estimates of the JEBAR term from observational data allow reliable diagnostic calculations? The authors give a negative answer to the first question. The JEBAR term need not give a true measure of the effect of bottom relief in a stratified ocean. A simple two-layer model provides examples. As to the second question, it is demonstrated ...


Differential Expression Of The Arabidopsis Nia1 And Nia2 Genes: Cytokinin-Induced Nitrate Reductase Activity Is Correlated With Increased Nia1 Transcription And Mrna Levels, Xiaodan Yu, Sujatha Sukumaran, László Márton Mar 1998

Differential Expression Of The Arabidopsis Nia1 And Nia2 Genes: Cytokinin-Induced Nitrate Reductase Activity Is Correlated With Increased Nia1 Transcription And Mrna Levels, Xiaodan Yu, Sujatha Sukumaran, László Márton

Faculty Publications

Nitrate reductase (NR) activity increased up to 14-fold in response to treatment of Arabidopsis thaliana seedlings with the cytokinin benzyladenine. NR induction was observed in seedlings germinated directly on cytokinin-containing medium, seedlings transferred to cytokinin medium, and seedlings grown in soil in which cytokinin was applied directly to the leaves. About the same level of induction was seen in both wild-type and Nia2-deletion mutants, indicating that increased NR activity is related to the expression of the minor NR gene, Nia1. The steady-state Nia1 mRNA level was increased severalfold in both wild-type and mutant seedlings after benzyladenine treatment. Transcript levels ...


The Foraging Ecology Of The Gray Rat Snake (Elaphe Obsoleta Spiloides)-Visual Stimuli Facilitate Location Of Arboreal Prey, Robert J. Cooper, Stephen J. Mullin Jan 1998

The Foraging Ecology Of The Gray Rat Snake (Elaphe Obsoleta Spiloides)-Visual Stimuli Facilitate Location Of Arboreal Prey, Robert J. Cooper, Stephen J. Mullin

Faculty Publications

We examined the responsiveness of adult gray rat snakes to avian prey in enclosures that simulated natural habitat conditions. Subjects searched for arboreal nest contents in the presence or absence of a bird model flown so as to simulate avian provisioning behavior. In the absence of the model, gray rat snake latency to capture prey was over 92 % greater than when searching for nest contents with the model. Snakes responded to model flight by turning their heads in the direction of its movement. We conclude that gray rat snakes perceive relatively distant visual cues from prey, and that nest provisioning ...


First-Year Survival And Growth Of Bareroot, Container, And Direct-Seeded Nuttall Oak Planted On Flood-Prone Agricultural Fields, Hans Michael Williams, Monica N. Craft Jan 1998

First-Year Survival And Growth Of Bareroot, Container, And Direct-Seeded Nuttall Oak Planted On Flood-Prone Agricultural Fields, Hans Michael Williams, Monica N. Craft

Faculty Publications

Container and 1-0 bare root Nuttall oak ( Quercus nuttallii, Palmer) seedlings were hand-planted, and acorns were direct- seeded, in a Sharkey soil (very fine, montmorillonitic, nonacid, thermic, Vertie Haplaquepts). The seedlings and seed were planted in January, February, March, and June, 1993. Flooding, to a depth of 2 meters, occurred on the study site from late March to late May. Seedlings planted in June were not flooded. Regardless of planting date, mean first-year survival for container seedlings was greater than 80 percent. Overall mean survival for bareroot seedlings was about 40 percent and direct-seeding survival was 30 percent. Bareroot seedling ...


Influence Of Planting Density On Diameter And Height In East Texas Pine Plantations, Young Jin Lee, J. David Lenhart Jan 1998

Influence Of Planting Density On Diameter And Height In East Texas Pine Plantations, Young Jin Lee, J. David Lenhart

Faculty Publications

The response of diameter and height of unthinned planted stands ofloblolly (Pinus taeda L.) and slash (Pinus elliottii Eng elm.)pine in East Texas to different classes of planting densities were analyzed. After tracking the development ofdiameterand heightfor 15yron a setofpennanentplots representing a broad range of plantation parameters, average diameter and average height trends were observed. For both species, average diameter values were significantly larger with lower planting densities. 1n contrast, average height growth is insensitive to planting density at younger age classes for loblolly and at older age classes for slash pine plantations.


Population Dynamics, Impacts, And Integrated Management Of Forest Defoliating Insects, David Kulhavy, W. G. Ross, R. R. Cahal Jan 1998

Population Dynamics, Impacts, And Integrated Management Of Forest Defoliating Insects, David Kulhavy, W. G. Ross, R. R. Cahal

Faculty Publications

Pine plantations on Typic Quartzipsamments in East Texas are difficult to establish. Forest management options following clearcutting are limited. An 8-year regeneration study of the growth and survival of loblolly, Pinus taeda, L. shortleaf, P. echinata Mill., slash, P. elliotii Engelm and longleaf pines P. palustris Mill. was conducted to determine optimum tree species and treatments for reforestation, and to recommend practical alternative land uses and management strategies for Typic Quartzipsamments. Successful regeneration provides new opportunities for insects and pathogens. Impacts of the Nantucket pine tip moth, R}iyacionia frustrana (Comstock), the Deodar weevil, Pissodes nemorensis, Germar, Annosus root rot ...


Inter-And Intraspecific Interaction Rates Of Three Species Of Lemurs (Subfamily Lemurinae) In An Enclosure At The Memphis Zoo And Aquarium, Stephen J. Mullin Jan 1998

Inter-And Intraspecific Interaction Rates Of Three Species Of Lemurs (Subfamily Lemurinae) In An Enclosure At The Memphis Zoo And Aquarium, Stephen J. Mullin

Faculty Publications

The use of mixed-species exhibits in zoological parks may influence the types and rates of interactions between individuals housed in such enclosures. Inter-and intraspecific behavioral interactions were observed for three species of lemurs (ring-tailed lemur, Lemur catta; black lemur, Eulemur macaco macaco; and black-and-white ruffed leumur, Varecia variegata variegata; in an enclosure designed to simulate characteristics of their natural habitat. Intraspecific interactions occurred more frequently than interspecific interactions, and little aggression was observed, either between or within species. Intraspecific interactions among black lemurs increased with decreasing ambient temperature. Black lemurs performed more intraspecific mutual contacts than either agonistic behaviors or ...


Urban Idealism Versus Wilderness Realism, Paul Risk Jan 1998

Urban Idealism Versus Wilderness Realism, Paul Risk

Faculty Publications

No abstract provided.


Wilderness In Eastern North America: Research, Management And Planning, David L. Kulhavy, Michael Legg, John H. Burde Jan 1998

Wilderness In Eastern North America: Research, Management And Planning, David L. Kulhavy, Michael Legg, John H. Burde

Faculty Publications

No abstract provided.


Impacts Of Three Timber Stand Improvement Thinning Options On Low Quality Southern Mixed-Hardwood Stands, Brian P. Oswald, Thomas H. Green Jan 1998

Impacts Of Three Timber Stand Improvement Thinning Options On Low Quality Southern Mixed-Hardwood Stands, Brian P. Oswald, Thomas H. Green

Faculty Publications

The impact of three thinning options (strip, single-tree selection, and strip with selection between strips) on lowquality southern mixed-hardwood stands was evaluated in northern Alabama. Although stand level comparisons showed no significant differences between options, individual dominant trees benefitted from the thinning treatments, exhibiting increased basal area growth during the period of the study. Intermediate treatments such as these thinning options may provide landowners with sufficient growth of selected high-quality trees to warrant the more intensive management activities on similar sites as utilized in this study.


Initial Investigation Of Height-Diameter Relationships Of Dominant Trees In The Mixed Hardwood Bottomland Forests Of East Texas, Brian P. Oswald, A. Gordon Holley, Leslie A. Dale, Gary D. Kronrad Jan 1998

Initial Investigation Of Height-Diameter Relationships Of Dominant Trees In The Mixed Hardwood Bottomland Forests Of East Texas, Brian P. Oswald, A. Gordon Holley, Leslie A. Dale, Gary D. Kronrad

Faculty Publications

Three to five dominant trees from each of 445 ten-factor variable radius inventory points were utilized to evaluate the height- diameter relationships of 13 species or genera found on bottomland hardwood sites throughout east Texas. Regression analysis was performed using the linear model such that height = (30 + (31 x (d.b.h.). The species were placed into six groups: (1) pines (Pinus taeda and P. enchinata) ; (2) water oak/willow oak/white oak/swamp chestnut oak (Quercus nigra)/(Q. phe//os)/(Q. alba)/(Q. michauxi1) ; (3) blackgum/laurel oak/overcup oak (Nyssa sylvatica)/(Q. laurifolia)/(Q. lyrata); (4) ash/maple ...


Red-Cockaded Woodpecker Nest-Cavity Selection: Relationships With Cavity Age And Resin Production, Richard N. Conner, Daniel Saenz, D. Craig Rudolph, W. G. Ross, David Kulhavy Jan 1998

Red-Cockaded Woodpecker Nest-Cavity Selection: Relationships With Cavity Age And Resin Production, Richard N. Conner, Daniel Saenz, D. Craig Rudolph, W. G. Ross, David Kulhavy

Faculty Publications

ABSTRACT.--We evaluated selection of nest sites by male Red-cockaded Woodpeckers (Picoides borealis) in Texas relative to the age of the cavity when only cavities excavated by the woodpecker were available and when both naturally excavated cavities and artificial cavities we available. We also evaluated nest-cavity selection relative to he ability of naturally excavated cavity trees to produce resin, which is used by the woodpeckers to maintain a barrier against predation by rat snakes (Elaphe spp.), Longleaf pines (Pinus palustris) selected by breeding males as nest trees produced significantly greater resin yields at 2, 8, and 24 h post-wounding than ...


Higher Prices And Shorter Rotations: Good News For Pine Plantation Investors, But . . ., Steven H. Bullard, Bob Daniels Jan 1998

Higher Prices And Shorter Rotations: Good News For Pine Plantation Investors, But . . ., Steven H. Bullard, Bob Daniels

Faculty Publications

Southern pine markets have changed dramatically in recent years. Our focus here is the changing forest economy, new price expectations, and new technologies for growing and utilizing pines. The major changes in southern pine markets are good news for forest landowners concerned with timber production-higher prices are increasing pine plantation returns, rotation lengths are decreasing, and the value of land in pine production is increasing.


Effects Of Stock Type And Fall Fertilization On Survival Of Longleaf Pine Seedlings Planted In Lignite Minespoil, Mary Anne Mcguire, Hans Michael Williams Jan 1998

Effects Of Stock Type And Fall Fertilization On Survival Of Longleaf Pine Seedlings Planted In Lignite Minespoil, Mary Anne Mcguire, Hans Michael Williams

Faculty Publications

One-year-old longleaf pine (Pinus palustris Mill.) seedlings were hand-planted in January 1996 on an east Texas minespoil site. Effects of two seedling stock types and four levels of preplanting fall fertilization on seedling survival were evaluated. Fertilizer treatments consisting of a single application of ammonium nitrate (73 kilograms per hectare N), phosphorus (81 kilograms per hectare P), diammonium phosphate (73 kilograms per hectare N, 81 kilograms per hectare P), or control (no fertilizer) were applied to bare-root and container seedlings in November 1995. Root growth potential, the ability of a seedling to initiate and elongate new roots when placed into ...


The Foraging Ecology Of The Gray Rat Snake (Elaphe Obsoleta Spiloides). Iii. Searching For Different Prey Types In Structurally Varied Habitats [Abstract], Stephen J. Mullin, Robert J. Cooper, William H. N. Gutzke Jan 1998

The Foraging Ecology Of The Gray Rat Snake (Elaphe Obsoleta Spiloides). Iii. Searching For Different Prey Types In Structurally Varied Habitats [Abstract], Stephen J. Mullin, Robert J. Cooper, William H. N. Gutzke

Faculty Publications

No abstract provided.