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2005 DOE Hydrogen Program Review PresentationCOST AND PERFORMANCE ENHANCEMENTS FOR A PEM FUEL CELL TURBOCOMPRESSOR (open access)

2005 DOE Hydrogen Program Review PresentationCOST AND PERFORMANCE ENHANCEMENTS FOR A PEM FUEL CELL TURBOCOMPRESSOR

The objectives of the program during the past year was to complete Technical Objectives 2 and 3 and initiate Technical Objective 4 are described. To assist the Department of Energy in the development of a low cost, reliable and high performance air compressor/expander. Technical Objective 1: Perform a turbocompressor systems PEM fuel cell trade study to determine the enhanced turbocompressor approach. Technical Objective 2: Using the results from technical objective 1, an enhanced turbocompressor will be fabricated. The design may be modified to match the flow requirements of a selected fuel cell system developer. Technical Objective 3: Design a cost and performance enhanced compact motor and motor controller. Technical Objective 4: Turbocompressor/motor controller development.
Date: April 1, 2005
Creator: Gee, Mark K.
System: The UNT Digital Library
Measurement of the azimuthal angle distribution of leptons from W boson decays as a function of the W transverse momentum in p anti-p collisions at s**(1/2) = 1.8-TeV (open access)

Measurement of the azimuthal angle distribution of leptons from W boson decays as a function of the W transverse momentum in p anti-p collisions at s**(1/2) = 1.8-TeV

We present the first measurement of the A{sub 2} and A{sub 3} angular coefficients of the W boson produced in proton-antiproton collisions. We study W {yields} ev{sub e} and W {yields} {mu}{nu}{sub {mu}} candidate events produced in association with at least one jet at CDF, during Run Ia and Run Ib of the Tevatron at {radical}s = 1.8 TeV. The corresponding integrated luminosity was 110 pb{sup -1}. The jet balances the transverse momentum of the W and introduces QCD effects in W boson production. The extraction of the angular coefficients is achieved through the direct measurement of the azimuthal angle of the charged lepton in the Collins-Soper rest-frame of the W boson. The angular coefficients are measured as a function of the transverse momentum of the W boson. The electron, muon, and combined results are in good agreement with the Standard Model prediction, up to order {alpha}{sub s}{sup 2} in QCD.
Date: April 1, 2005
Creator: Acosta, D.; Affolder, Anthony A.; Albrow, M. G.; Ambrose, D.; Amidei, D.; Anikeev, K. et al.
System: The UNT Digital Library
K0(s) and Lambda0 production studies in p anti-p collisions at s**(1/2) = 1800 and 630-GeV (open access)

K0(s) and Lambda0 production studies in p anti-p collisions at s**(1/2) = 1800 and 630-GeV

The authors present a study of the production of K{sub s}{sup 0} and {Lambda}{sup 0} in inelastic p{bar p} collisions at {radical}s = 1800 and 630 GeV using data collected by the CDF experiment at the Fermilab Tevatron. Analyses of K{sub s}{sup 0} and {Lambda}{sup 0} multiplicity and transverse momentum distributions, as well as of the dependencies of the average number and (p{sub T}) of K{sub s}{sup 0} and {Lambda}{sup 0} on charged particle multiplicity are reported. Systematic comparisons are performed for the full sample of inelastic collisions, and for the low and high momentum transfer subsamples, at the two energies. The p{sub T} distributions extend above 8 GeV/c, showing a (p{sub T}) higher than previous measurements. The dependence of the mean K{sub s}{sup 0}({Lambda}{sup 0}) p{sub T} on the charged particle multiplicity for the three samples shows a behavior analogous to that of charged primary tracks.
Date: April 1, 2005
Creator: Acosta, D.; Affolder, Anthony A.; Albrow, M. G.; Ambrose, D.; Amidei, D.; Anikeev, K. et al.
System: The UNT Digital Library
Background reduction in cryogenic detectors (open access)

Background reduction in cryogenic detectors

This paper discusses the background reduction and rejection strategy of the Cryogenic Dark Matter Search (CDMS) experiment. Recent measurements of background levels from CDMS II at Soudan are presented, along with estimates for future improvements in sensitivity expected for a proposed SuperCDMS experiment at SNOLAB.
Date: April 1, 2005
Creator: Bauer, Daniel A.
System: The UNT Digital Library
Stability of barrier buckets with short barrier separations (open access)

Stability of barrier buckets with short barrier separations

A barrier bucket with very short or zero rf-barrier separation (relative to the barrier widths) has its synchrotron tune decreasing from a very large value towards the bucket boundary. As a result, chaotic region may form near the bucket center and extends outward under increasing modulation of rf voltage and/or rf phase. Application is made to those barrier buckets used in momentum mining at the Fermilab Recycler Ring.
Date: April 1, 2005
Creator: Ng, K. Y.
System: The UNT Digital Library
Measurement of the cross section for t anti-t production in p anti-p collisions using the kinematics of lepton + jets events (open access)

Measurement of the cross section for t anti-t production in p anti-p collisions using the kinematics of lepton + jets events

The authors present a measurement of the top pair production cross section in p{bar p} collisions at {radical}s = 1.96 TeV. We collect a data sample with an integrated luminosity of 194 {+-} 11 pb{sup -1} with the CDF II detector at the Fermilab Tevatron. We use an artificial neural network technique to discriminate between top pair production and background processes in a sample of 519 lepton + jets events, which have one isolated energetic charged lepton, large missing transverse energy and at least three energetic jets. We measure the top pair production cross section to be {sigma}{sub t{bar t}} = 6.6 {+-} 1.1 {+-} 1.5 pb, where the first uncertainty is statistical and the second is systematic.
Date: April 1, 2005
Creator: Acosta, D.; Adelman, J.; Affolder, Anthony A.; Akimoto, T.; Albrow, M. G.; Ambrose, D. et al.
System: The UNT Digital Library
Search for supersymmetry via associated production of charginos and neutralinos in final states with three leptons (open access)

Search for supersymmetry via associated production of charginos and neutralinos in final states with three leptons

None
Date: April 1, 2005
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
System: The UNT Digital Library
Application of a Java-based, univel geometry, neutral particle Monte Carlo code to the searchlight problem (open access)

Application of a Java-based, univel geometry, neutral particle Monte Carlo code to the searchlight problem

A univel geometry, neutral particle Monte Carlo transport code, written entirely in the Java programming language, is under development for medical radiotherapy applications. The code uses ENDF-VI based continuous energy cross section data in a flexible XML format. Full neutron-photon coupling, including detailed photon production and photonuclear reactions, is included. Charged particle equilibrium is assumed within the patient model so that detailed transport of electrons produced by photon interactions may be neglected. External beam and internal distributed source descriptions for mixed neutron-photon sources are allowed. Flux and dose tallies are performed on a univel basis. A four-tap, shift-register-sequence random number generator is used. Initial verification and validation testing of the basic neutron transport routines is underway. The searchlight problem was chosen as a suitable first application because of the simplicity of the physical model. Results show excellent agreement with analytic solutions. Computation times for similar numbers of histories are comparable to other neutron MC codes written in C and FORTRAN.
Date: April 1, 2005
Creator: Wemple, Charles A. & Cogliati, Joshua J.
System: The UNT Digital Library
Abundance of Green Tree Frogs and Insects in Artificial Canopy Gaps in a Bottomland Hardwood Forest. (open access)

Abundance of Green Tree Frogs and Insects in Artificial Canopy Gaps in a Bottomland Hardwood Forest.

ABSTRACT - We found more green tree frogs ( Hyla cinerea) n canopv gaps than in closed canopy forest. Of the 331 green tree frogs observed, 88% were in canopv gaps. Likewise, higher numbers and biomasses of insects were captured in the open gap habitat Flies were the most commonlv collected insect group accounting for 54% of the total capture. These data suggest that one reason green tree frogs were more abundant in canopy gaps was the increased availability of prey and that small canopy gaps provide early successional habitats that are beneficial to green tree frog populations.
Date: April 1, 2005
Creator: Horn, Scott; Hanula, James, L.; Ulyshen, Michael D. & Kilgo, John, C.
System: The UNT Digital Library
Process Control Systems in the Chemical Industry: Safety vs. Security (open access)

Process Control Systems in the Chemical Industry: Safety vs. Security

Traditionally, the primary focus of the chemical industry has been safety and productivity. However, recent threats to our nation’s critical infrastructure have prompted a tightening of security measures across many different industry sectors. Reducing vulnerabilities of control systems against physical and cyber attack is necessary to ensure the safety, security and effective functioning of these systems. The U.S. Department of Homeland Security has developed a strategy to secure these vulnerabilities. Crucial to this strategy is the Control Systems Security and Test Center (CSSTC) established to test and analyze control systems equipment. In addition, the CSSTC promotes a proactive, collaborative approach to increase industry's awareness of standards, products and processes that can enhance the security of control systems. This paper outlines measures that can be taken to enhance the cybersecurity of process control systems in the chemical sector.
Date: April 1, 2005
Creator: Hahn, Jeffrey & Anderson, Thomas
System: The UNT Digital Library
SIG -- The Role of Human-Computer Interaction in Next-Generation Control Rooms (open access)

SIG -- The Role of Human-Computer Interaction in Next-Generation Control Rooms

The purpose of this CHI Special Interest Group (SIG) is to facilitate the convergence between human-computer interaction (HCI) and control room design. HCI researchers and practitioners actively need to infuse state-of-the-art interface technology into control rooms to meet usability, safety, and regulatory requirements. This SIG outlines potential HCI contributions to instrumentation and control (I&C) and automation in control rooms as well as to general control room design.
Date: April 1, 2005
Creator: Boring, Ronald L.; Hugo, Jacques; Richard, Christian & Dudenhoeffer, Donald D.
System: The UNT Digital Library
The National Atmospheric Release Advisory Center (NARAC) Modeling and Decision Support System for Radiological and Nuclear Emergency Preparedness and Response (open access)

The National Atmospheric Release Advisory Center (NARAC) Modeling and Decision Support System for Radiological and Nuclear Emergency Preparedness and Response

This paper describes the tools and services provided by the National Atmospheric Release Advisory Center (NARAC) at Lawrence Livermore National Laboratory (LLNL) for modeling the impacts of airborne hazardous materials. NARAC provides atmospheric plume modeling tools and services for chemical, biological, radiological, and nuclear airborne hazards. NARAC can simulate downwind effects from a variety of scenarios, including fires, industrial and transportation accidents, radiation dispersal device explosions, hazardous material spills, sprayers, nuclear power plant accidents, and nuclear detonations. NARAC collaborates with several government agencies and laboratories in order to accomplish its mission. The NARAC suite of software tools include simple stand-alone, local-scale plume modeling tools for end-user's computers, and Web- and Internet-based software to access advanced modeling tools and expert analyses from the national center at LLNL. Initial automated, 3-D predictions of plume exposure limits and protective action guidelines for emergency responders and managers are available from the center in 5-10 minutes. These can be followed immediately by quality-assured, refined analyses by 24 x 7 on-duty or on-call NARAC staff. NARAC continues to refine calculations using updated on-scene information, including measurements, until all airborne releases have stopped and the hazardous threats are mapped and impacts assessed. Model predictions include the 3-D …
Date: April 1, 2005
Creator: Nasstrom, J. S.; Sugiyama, G.; Baskett, R.; Larsen, S. & Bradley, M.
System: The UNT Digital Library
GIS INTERNET MAP SERVICE FOR DISPLAYING SELENIUM CONTAMINATION DATA IN THE SOUTHEASTERN IDAHO PHOSPHATE MINING RESOURCE AREA (open access)

GIS INTERNET MAP SERVICE FOR DISPLAYING SELENIUM CONTAMINATION DATA IN THE SOUTHEASTERN IDAHO PHOSPHATE MINING RESOURCE AREA

Selenium is present in waste rock/overburden that is removed during phosphate mining in southeastern Idaho. Waste rock piles or rock used during reclamation can be a source of selenium (and other metals) to streams and vegetation. Some instances (in 1996) of selenium toxicity in grazing sheep and horses caused public health and environmental concerns, leading to Idaho Department of Environmental Quality (DEQ) involvement. The Selenium Information System Project is a collaboration among the DEQ, the United States Forest Service (USFS), the Bureau of Land Management (BLM), the Idaho Mining Association (IMA), Idaho State University (ISU), and the Idaho National Laboratory (INL)2. The Selenium Information System is a centralized data repository for southeastern Idaho selenium data. The data repository combines information that was previously in numerous agency, mining company, and consultants’ databases and web sites. These data include selenium concentrations in soil, water, sediment, vegetation and other environmental media, as well as comprehensive mine information. The Idaho DEQ spearheaded a selenium area-wide investigation through voluntary agreements with the mining companies and interagency participants. The Selenium Information System contains the results of that area-wide investigation, and many other background documents. As studies are conducted and remedial action decisions are made the resulting …
Date: April 1, 2005
Creator: Mayes, Roger; White, Sera & Lee, Randy
System: The UNT Digital Library
Design Attributes and Scale Up Testing of Annular Centrifugal Contactors (open access)

Design Attributes and Scale Up Testing of Annular Centrifugal Contactors

Annular centrifugal contactors are being used for rapid yet efficient liquid- liquid processing in numerous industrial and government applications. Commercialization of this technology began eleven years ago and now units with throughputs ranging from 0.25 to 700 liters per minute are readily available. Separation, washing, and extraction processes all benefit from the use of this relatively new commercial tool. Processing advantages of this technology include: low in-process volume per stage, rapid mixing and separation in a single unit, connection-in-series for multi-stage use, and a wide operating range of input flow rates and phase ratios without adjustment. Recent design enhancements have been added to simplify maintenance, improve inspection ability, and provide increased reliability. Cartridge-style bearing and mechanical rotary seal assemblies that can include liquid-leak sensors are employed to enhance remote operations, minimize maintenance downtime, prevent equipment damage, and extend service life. Clean-in-place capability eliminates the need for disassembly, facilitates the use of contactors for feed clarification, and can be automated for continuous operation. In nuclear fuel cycle studies, aqueous based separations are being developed that efficiently partition uranium, actinides, and fission products via liquid-liquid solvent extraction. Thus, annular centrifugal contactors are destined to play a significant role in the design of …
Date: April 1, 2005
Creator: Meikrantz, David H. & Law, Jack D.
System: The UNT Digital Library
Advanced Test Reactor Testing Experience: Past, Present and Future (open access)

Advanced Test Reactor Testing Experience: Past, Present and Future

The Advanced Test Reactor (ATR), at the Idaho National Laboratory (INL), is one of the world’s premier test reactors for providing the capability for studying the effects of intense neutron and gamma radiation on reactor materials and fuels. The physical configuration of the ATR, a 4-leaf clover shape, allows the reactor to be operated at different power levels in the corner “lobes” to allow for different testing conditions for multiple simultaneous experiments. The combination of high flux (maximum thermal neutron fluxes of 1E15 neutrons per square centimeter per second and maximum fast [E>1.0 MeV] neutron fluxes of 5E14 neutrons per square centimeter per second) and large test volumes (up to 48" long and 5.0" diameter) provide unique testing opportunities. The current experiments in the ATR are for a variety of test sponsors -- US government, foreign governments, private researchers, and commercial companies needing neutron irradiation services. There are three basic types of test configurations in the ATR. The simplest configuration is the sealed static capsule, wherein the target material is placed in a capsule, or plate form, and the capsule is in direct contact with the primary coolant. The next level of complexity of an experiment is an instrumented lead …
Date: April 1, 2005
Creator: Marshall, Frances M.
System: The UNT Digital Library
MCWO - Linking MCNP And ORIGEN2 For Fuel Burnup Analysis (open access)

MCWO - Linking MCNP And ORIGEN2 For Fuel Burnup Analysis

The UNIX BASH (Bourne Again Shell) script MCWO has been developed at the Idaho National Engineering and Environment Laboratory (INEEL) to couple the Monte Carlo transport code MCNP with the depletion and buildup code ORIGEN2. MCWO is a fully automated tool that links the Monte Carlo transport code MCNP with the radioactive decay and burnup code ORIGEN2. MCWO can handle a large number of fuel burnup and material loading specifications, Advanced Test Reactor (ATR) powers, and irradiation time intervals. The program processes input from the user that specifies the system geometry, initial material compositions, feed/removal specifications, and other code-specific parameters. Calculated results from MCNP, ORIGEN2, and data process module calculations are then output successively as the code runs. The principal function of MCWO is to transfer one-group cross-section and flux values from MCNP to ORIGEN2, and then transfer the resulting material compositions (after irradiation and/or decay) from ORIGEN2 back to MCNP in a repeated, cyclic fashion. The basic requirement of the code is that the user have a working MCNP input file and other input parameters; all interaction with ORIGEN2 and other calculations are performed by UNIX BASH script MCWO. This paper presents the MCWO-calculated results of the RERTR-1 and …
Date: April 1, 2005
Creator: Chang, Gray S
System: The UNT Digital Library
The Wolbachia genome of Brugia malayi: Endosymbiont evolution within a human pathogenic nematode (open access)

The Wolbachia genome of Brugia malayi: Endosymbiont evolution within a human pathogenic nematode

None
Date: April 1, 2005
Creator: Foster, Jeremy; Ganatra, Mehul; Kamal, Ibrahim; Ware, Jennifer; Makarova, Kira; Ivanova, Natalia et al.
System: The UNT Digital Library
Objectives, Strategies, and Challenges for the Advanced Fuel Cycle Initiative (open access)

Objectives, Strategies, and Challenges for the Advanced Fuel Cycle Initiative

This paper will summarize the objectives, strategies, and key chemical separation challenges for the Advanced Fuel Cycle Initiative (AFCI). The major objectives are as follows: Waste management - defer the need for a second geologic repository for a century or more, Proliferation resistance - be more resistant than the existing PUREX separation technology or uranium enrichment, Energy sustainability - turn waste management liabilities into energy source assets to ensure that uranium ore resources do not become a constraint on nuclear power, and Systematic, safe, and economic management of the entire fuel cycle. There are four major strategies for the disposal of civilian spent fuel: Once-through - direct disposal of all discharged nuclear fuel, Limited recycle - recycle transuranic elements once and then direct disposal, Continuous recycle - recycle transuranic elements repeatedly, and Sustained recycle - same as continuous except previously discarded depleted uranium is also recycled. The key chemical separation challenges stem from the fact that the components of spent nuclear fuel vary greatly in their influence on achieving program objectives. Most options separate uranium to reduce the weight and volume of waste and the number and cost of waste packages that require geologic disposal. Separated uranium can also be …
Date: April 1, 2005
Creator: Piet, Steven; Dixon, Brent; Shropshire, David; Hill, Robert; Wigeland, Roald; Schneider, Erich et al.
System: The UNT Digital Library
Development of Technologies for the Simultaneous Separation of Cesium and Strontium from Spent Nuclear Fuel as Part of an Advanced Fuel Cycle (open access)

Development of Technologies for the Simultaneous Separation of Cesium and Strontium from Spent Nuclear Fuel as Part of an Advanced Fuel Cycle

As part of the Advanced Fuel Cycle Initiative, two solvent extraction technologies are being developed to simultaneously separate cesium and strontium from dissolved spent nuclear fuel. The first process utilizes a solvent consisting of chlorinated cobalt dicarbollide and polyethylene glycol extractants in a phenyltrifluoromethyl sulfone diluent. Recent improvements to the process include development of a new, non-nitroaromatic diluent and development of new stripping reagents, including a regenerable strip reagent that can be recovered and recycled. Countercurrent flowsheets have been designed and tested on simulated and actual spent nuclear fuel feed streams with both cesium and strontium removal efficiencies of greater than 99 %. The second process developed to simultaneously separate cesium and strontium from spent nuclear fuel is based on two highly-specific extractants: 4,4',(5')-Di-(t-butyldicyclo-hexano)-18-crown-6 (DtBuCH18C6) and Calix[4]arene-bis-(tert-octylbenzo-crown-6) (BOBCalixC6). The DtBuCH18C6 extractant is selective for strontium and the BOBCalixC6 extractant is selective for cesium. A solvent composition has been developed that enables both elements to be removed together and, in fact, a synergistic effect was observed with strontium distributions in the combined solvent that are much higher that in the strontium extraction (SREX) process. Initial laboratory test results of the new combined cesium and strontium extraction process indicate good extraction and …
Date: April 1, 2005
Creator: Law, Jack D.; HErbst, R. Scott; Meikrantz, David H.; Peterman, Dean R.; Riddle, Catherine L.; Tillotson, Richard D. et al.
System: The UNT Digital Library
Modeling flow of mineralized carbon dioxide slurry (open access)

Modeling flow of mineralized carbon dioxide slurry

Direct mineral carbonation was investigated at Albany Research Center (US DOE) as a means to sequester carbon dioxide into stable mineral matrices. Although previous work focused on treating Mg-containing minerals in conventional autoclaves, recent work has been done using pipeline-reactor technology for the high-temperature, high-pressure (HTHP) reaction of the minerals in aqueous/CO2 media. Sequestration of CO2 using above-ground reactors may be uneconomical, but the technology may also be applicable in geological sequestration of CO2. Progress is described in using a prototype HTHP flow-loop reactor to model flow in the dynamic three-phase system to help determine the pumping-energy requirements to optimize reactivity.
Date: April 1, 2005
Creator: Penner, Larry R.; Dahlin, David C.; Gerdemann, Stephen J. & Saha, K.K. (Mechanical and Aerospace Engineering Dept., Computational Fluid Dynamics Laboratory, Arizona State University)
System: The UNT Digital Library
Hydrogen Fleet and Infrastructure Demonstration and Validation Program: Data Analysis Overview (open access)

Hydrogen Fleet and Infrastructure Demonstration and Validation Program: Data Analysis Overview

None
Date: April 1, 2005
Creator: Welch, C.; Wipke, K.; Gronich, S. & Garbak, J.
System: The UNT Digital Library
Design of a non-scaling FFAG accelerator for proton therapy (open access)

Design of a non-scaling FFAG accelerator for proton therapy

In recent years there has been a revival of interest in Fixed Field Alternating Gradient (FFAG) accelerators. In Japan a number have been built, or are under construction. A new non-scaling approach to the FFAG reduces the required orbit offsets during acceleration and the size of the required aperture, while maintaining the advantage of the low cost magnets associated with fixed fields. An advantage of the non-scaling FFAG accelerator, with respect to synchrotrons, is the fixed field and hence the possibility of high current and high repetition rate for spot scanning. There are possible advantages of the nonscaling design with respect to fixed-field cyclotrons. The non-scaling FFAG allows strong focusing and hence smaller aperture requirements compared to scaling designs, thus leading to very low losses and better control over the beam. We present, here, a non-scaling FFAG designed to be used for proton therapy.
Date: April 1, 2005
Creator: Trbojevic, D.; Ruggiero, A. G.; Keil, E.; Neskovic, N.; Belgrade, Vinca & Sessler, A.
System: The UNT Digital Library
Genomic sequencing of Pleistocene cave bears (open access)

Genomic sequencing of Pleistocene cave bears

Despite the information content of genomic DNA, ancient DNA studies to date have largely been limited to amplification of mitochondrial DNA due to technical hurdles such as contamination and degradation of ancient DNAs. In this study, we describe two metagenomic libraries constructed using unamplified DNA extracted from the bones of two 40,000-year-old extinct cave bears. Analysis of {approx}1 Mb of sequence from each library showed that, despite significant microbial contamination, 5.8 percent and 1.1 percent of clones in the libraries contain cave bear inserts, yielding 26,861 bp of cave bear genome sequence. Alignment of this sequence to the dog genome, the closest sequenced genome to cave bear in terms of evolutionary distance, revealed roughly the expected ratio of cave bear exons, repeats and conserved noncoding sequences. Only 0.04 percent of all clones sequenced were derived from contamination with modern human DNA. Comparison of cave bear with orthologous sequences from several modern bear species revealed the evolutionary relationship of these lineages. Using the metagenomic approach described here, we have recovered substantial quantities of mammalian genomic sequence more than twice as old as any previously reported, establishing the feasibility of ancient DNA genomic sequencing programs.
Date: April 1, 2005
Creator: Noonan, James P.; Hofreiter, Michael; Smith, Doug; Priest, JamesR.; Rohland, Nadin; Rabeder, Gernot et al.
System: The UNT Digital Library
Herbivorous insect response to group selection cutting in a southeastern bottomland hardwood forest. (open access)

Herbivorous insect response to group selection cutting in a southeastern bottomland hardwood forest.

ABSTRACT Malaise and pitfall traps were used to sample herbivorous insects in canopy gaps created by group-selection cutting in a bottomland hardwood forest in South Carolina. The traps were placed at the centers, edges, and in the forest adjacent to gaps of different sizes (0.13, 0.26, and 0.50 ha) and ages (1 and 7 yr old) during four sampling periods in 2001. Overall, the abundance and species richness of insect herbivores were greater at the centers of young gaps than at the edge of young gaps or in the forest surrounding young gaps. There were no differences in abundance or species richness among old gap locations (i.e., centers, edges, and forest), and we collected significantly more insects in young gaps than old gaps. The insect communities in old gaps were more similar to the forests surrounding them than young gap communities were to their respective forest locations, but the insect communities in the two forests locations (surrounding young and old gaps) had the highest percent similarity of all. Although both abundance and richness increased in the centers of young gaps with increasing gap size, these differences were not significant.Weattribute the increased numbers of herbivorous insects to the greater abundance of …
Date: April 1, 2005
Creator: Ulyshen, Michael D.; Hanula, James L.; Horn, Scott & Moorman., Christopher E.
System: The UNT Digital Library