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4,170 Matching Results
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The Muon system of the run II D0 detector
The authors describe the design, construction and performance of the upgraded D0 muon system for Run II of the Fermilab Tevatron collider. Significant improvements have been made to the major subsystems of the D0 muon detector: trigger scintillation counters, tracking detectors, and electronics. The Run II central muon detector has a new scintillation counter system inside the iron toroid and an improved scintillation counter system outside the iron toroid. In the forward region, new scintillation counter and tracking systems have been installed. Extensive shielding has been added in the forward region. A large fraction of the muon system electronics is also new.
Date:
March 1, 2005
Creator:
Abazov, V. M.; Acharya, B. S.; Alexeev, G. D.; Alkhazov, G.; Anosov, V. A.; Baldin, B. et al.
Object Type:
Article
System:
The UNT Digital Library
Development of Highly Durable and Reactive Regenerable Magnesium-Based Sorbents for CO2 Separation in Coal Gasification Process
The specific objective of this project was to develop physically durable and chemically regenerable MgO-based sorbents that can remove carbon dioxide from raw coal gas at operating condition prevailing in IGCC processes. A total of sixty two (62) different sorbents were prepared in this project. The sorbents were prepared either by various sol-gel techniques (22 formulations) or modification of dolomite (40 formulations). The sorbents were prepared in the form of pellets and in granular forms. The solgel based sorbents had very high physical strength, relatively high surface area, and very low average pore diameter. The magnesium content of the sorbents was estimated to be 4-6 % w/w. To improve the reactivity of the sorbents toward CO{sub 2}, The sorbents were impregnated with potassium salts. The potassium content of the sorbents was about 5%. The dolomite-based sorbents were prepared by calcination of dolomite at various temperature and calcination environment (CO{sub 2} partial pressure and moisture). Potassium carbonate was added to the half-calcined dolomite through wet impregnation method. The estimated potassium content of the impregnated sorbents was in the range of 1-6% w/w. In general, the modified dolomite sorbents have significantly higher magnesium content, larger pore diameter and lower surface area, resulting …
Date:
June 1, 2005
Creator:
Abbasian, Javad; Khayyat, Armin Hassanzadeh & Slimane, Rachid B.
Object Type:
Report
System:
The UNT Digital Library
A Search for gravitational waves associated with the gamma ray burst GRB030329 using the LIGO detectors
We have performed a search for bursts of gravitational waves associated with the very bright Gamma Ray Burst GRB030329, using the two detectors at the LIGO Hanford Observatory. Our search covered the most sensitive frequency range of the LIGO detectors (approximately 80-2048 Hz), and we specifically targeted signals shorter than {approx_equal}150 ms. Our search algorithm looks for excess correlated power between the two interferometers and thus makes minimal assumptions about the gravitational waveform. We observed no candidates with gravitational wave signal strength larger than a pre-determined threshold. We report frequency dependent upper limits on the strength of the gravitational waves associated with GRB030329. Near the most sensitive frequency region, around {approx_equal}250 Hz, our root-sum-square (RSS) gravitational wave strain sensitivity for optimally polarized bursts was better than h{sub RSS} {approx_equal} 6 x 10{sup -21} Hz{sup -1/2}. Our result is comparable to the best published results searching for association between gravitational waves and GRBs.
Date:
January 1, 2005
Creator:
Abbott, B.; Abbott, R.; Adhikari, R.; Ageev, A.; Allen, B.; Amin, R. et al.
Object Type:
Article
System:
The UNT Digital Library
Atmospheric Mercury Concentrations Near Salmon Falls Creek Reservoir - Phase 1
Elemental and reactive gaseous mercury (EGM/RGM) were measured in ambient air concentrations over a two-week period in July/August 2005 near Salmon Falls Creek Reservoir, a popular fishery located 50 km southwest of Twin Falls, Idaho. A fish consumption advisory for mercury was posted at the reservoir in 2002 by the Idaho Department of Health and Welfare. The air measurements were part of a multi-media (water, sediment, precipitation, air) study initiated by the Idaho Department of Environmental Quality and the U.S. Environmental Protection Agency (EPA) Region 10 to identify potential sources of mercury contamination to the reservoir. The sampling site is located about 150 km northeast of large gold mining operations in Nevada, which are known to emit large amounts of mercury to the atmosphere (est. 2,200 kg/y from EPA 2003 Toxic Release Inventory). The work was co-funded by the Idaho National Laboratory’s Community Assistance Program and has a secondary objective to better understand mercury inputs to the environment near the INL, which lies approximately 230 km to the northeast. Sampling results showed that both EGM and RGM concentrations were significantly elevated (~ 30 – 70%, P<0.05) compared to known regional background concentrations. Elevated short-term RGM concentrations (the primary form that …
Date:
October 1, 2005
Creator:
Abbott, M. L.
Object Type:
Report
System:
The UNT Digital Library
Basin amplification of seismic waves in the city of Pahrump, Nevada.
Sedimentary basins can increase the magnitude and extend the duration of seismic shaking. This potential for seismic amplification is investigated for Pahrump Valley, Nevada-California. The Pahrump Valley is located approximately 50 km northwest of Las Vegas and 75 km south of the Nevada Test Site. Gravity data suggest that the city of Pahrump sits atop a narrow, approximately 5 km deep sub-basin within the valley. The seismic amplification, or ''site effect'', was investigated using a combination of in situ velocity modeling and comparison of the waveforms and spectra of weak ground motion recorded in the city of Pahrump, Nevada, and those recorded in the nearby mountains. Resulting spectral ratios indicate seismic amplification factors of 3-6 over the deepest portion of Pahrump Valley. This amplification predominantly occurs at 2-2.5 Hz. Amplification over the deep sub-basin is lower than amplification at the sub-basin edge, location of the John Blume and Associates PAHA seismic station, which recorded many underground nuclear tests at the Nevada Test Site. A comprehensive analysis of basin amplification for the city of Pahrump should include 3-D basin modeling, due to the extreme basement topography of the Pahrump Valley.
Date:
July 1, 2005
Creator:
Abbott, Robert E.
Object Type:
Report
System:
The UNT Digital Library
Electric Utility Restructuring: Maintaining Bulk Power System Reliability
None
Date:
February 1, 2005
Creator:
Abel, Amy; Parker, Larry B. & Stitt, Steven C.
Object Type:
Report
System:
The UNT Digital Library
A Measurement of the K0 charge radius and a CP violating asymmetry together with a search for CP violating e1 direct photon emission in the rare decay K(L) ---> pi+ pi- e+ e-
Using the complete KTeV data set of 5241 candidate K{sub L} {yields} {pi}{sup +}{pi}{sup -}e{sup +}e{sup -} decays (including an estimated background of 204 {+-} 14 events), we have measured the coupling g{sub CR} = 0.163 {+-} 0.014 (stat) {+-} 0.023 (syst) of the CP conserving charge radius process and from it determined a K{sup 0} charge radius of <r{sub K{sup 0}}{sup 2}> = (-0.077 {+-} 0.007(stat) {+-} 0.011(syst))fm{sup 2}. We have also determined a first experimental upper limit of 0.04 (90% CL) for the ratio |g{sub E1}|/|g{sub M1}| of the coupling for the E1 direct photon emission process relative to the coupling for M1 direct photon emission process. We also report the measurement of |g{sub M1}| including its associated vector form factor |{bar g}{sub M1}|1 + a{sub 1}/a{sub 2}/(M{sub p}{sup 2} - M{sub K}{sup 2})+2M{sub K}E{sub {gamma}*} where |{bar g}{sub M1}| = 1.11 {+-} 0.12 (stat) {+-} 0.08 (syst) and a{sub 1}/a{sub 2} = (-0.744 {+-} 0.027 (stat) {+-} 0.032 (syst)) GeV{sup 2}/c{sup 2}. In addition, a measurement of the manifestly CP violating asymmetry of magnitude (13.6 {+-} 1.4 (stat) {+-} 1.5 (syst))% in the CP and T odd angle {phi} between the decay planes of the e{sup +}e{sup …
Date:
August 1, 2005
Creator:
Abouzaid, E.; Arenton, M.; Barker, A. R.; Bellantoni, L.; Bellavance, A.; Blucher, E. et al.
Object Type:
Article
System:
The UNT Digital Library
Improved Performance in CuInSe2 and Surface-Modified CuGaSe2 Solar Cells
In this paper, we present an update and review on the progress made in the development of low-bandgap CuInSe2 (CIS) and wide-bandgap CuGaSe2 (CGS) solar cells. Our research project is primarily concerned with the optimization of the bottom and top cells of the tandem solar cell. This past year, we achieved new world record total-area efficiencies of 15.0% and 10.2% for CIS and surface-modified CGS solar cells, respectively. These achievements were possible by modifying the growth process for CIS and CGS absorbers. We attempt to modify the surface region of the CGS absorber to be CIGS-like in composition. In the mean time, we are designing a mechanical-stacked tandem solar cell where the CIS cell serves as the bottom cell.
Date:
January 1, 2005
Creator:
AbuShama, J.; Noufi, R. & Johnston, S.
Object Type:
Article
System:
The UNT Digital Library
Improved Performance in CuInSe2 and Surface-Modified CuGaSe2 Solar Cells
In this paper, we present an update and review on the progress made in the development of low-bandgap CuInSe2 (CIS) and wide-bandgap CuGaSe2 (CGS) solar cells. Our research project is a primarily concerned with the optimization of the bottom and top cells of the tandem solar cell. This past year, we established new record total-area efficiencies of 15.0% and 10.2% for CIS and surface-modified CGS solar cells, respectively. These achievements were possible by modifying the growth process for CIS and CGS absorbers. We attempt to modify the surface region of the CGS absorber to be CIGS-like in composition. We also have designed a mechanical-stacked tandem solar cell where the 15% CIS cell serves as the bottom cell. The NREL-confirmed total-area efficiency for this tandem device is 15.31%.
Date:
February 1, 2005
Creator:
AbuShama, J.; Noufi, R.; Johnston, S.; Ward, S. & Wu, X.
Object Type:
Article
System:
The UNT Digital Library
Search for second-generation scalar leptoquarks in p anti-p collisions at s**(1/2) = 1.96-TeV
Results on a search for pair production of second generation scalar leptoquark in p{bar p} collisions at {radical}s=1.96 TeV are reported. The data analyzed were collected by the CDF detector during the 2002-2003 Tevatron Run II and correspond to an integrated luminosity of 198 pb{sup -1}. Leptoquarks (LQ) are sought through their decay into (charged) leptons and quarks, with final state signatures represented by two muons and jets and one muon, large transverse missing energy and jets. We observe no evidence for LQ production and derive 95% C.L. upper limits on the LQ production cross sections as well as lower limits on their mass as a function of {beta}, where {beta} is the branching fraction for LQ {yields} {mu}q.
Date:
December 1, 2005
Creator:
Abulencia, A.; Acosta, D.; Adelman, J.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Object Type:
Article
System:
The UNT Digital Library
Measurement of the dipion mass spectrum in X(3872) ---> J/psi pi+ pi- decays
The authors measure the dipion mass spectrum in X(3872) {yields} J/{psi}{pi}{sup +}{pi}{sup -} decays using 360 pb{sup -1} of {bar p}p collisions at {radical}s = 1.96 TeV collected with the CDF II detector. The spectrum is fit with predictions for odd C-parity ({sup 3}S{sub 1}, {sup 1}P{sub 1}, and {sup 3}D{sub J}) charmonia decaying to J/{psi}{pi}{sup +}{pi}{sup -}, as well as event C-parity states in which the pions are from {rho}{sup 0} decay. The latter case also encompasses exotic interpretations, such as a D{sup 0}{bar D}*{sup 0} molecule. Only the {sup 3}S{sub 1} and J/{psi} {rho} hypotheses are compatible with the data. Since {sup 3}S{sub 1} is untenable on other grounds, decay via J/{psi} {rho} is favored, which implies C = +1 for the X(3872). Models for different J/{psi}-{rho} angular momenta L are considered. Flexibility in the models, especially the introduction of {rho}-{omega} interference, enable good descriptions of the data for both L = 0 and 1.
Date:
December 1, 2005
Creator:
Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Object Type:
Article
System:
The UNT Digital Library
Measurement of the helicity of W bosons in top-quark decays
We measure the branching fraction of the top quark to longitudinally and right-handed polarized W bosons, F{sub 0} and F{sub +}, using approximately 200 pb{sup -1} of p{bar p} collisions collected by the CDF II detector. We analyze two quantities sensitive to the W helicity: the invariant mass of the charged lepton and the bottom-quark jet in the decay t {yields} Wb {yields} {ell}{nu}b (where {ell} = e or {mu}), and the transverse momentum of the charged lepton. We find F{sub 0} = 0.74{sub -0.34}{sup +0.22}, and F{sub +} < 0.27 at the 95% confidence level. These measurements are in agreement with the standard model predictions.
Date:
November 1, 2005
Creator:
Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Object Type:
Article
System:
The UNT Digital Library
Measurement of the inclusive jet cross section in p anti-p interactions at s**(1/2) = 1.96-TeV using a cone-based jet algorithm
None
Date:
December 1, 2005
Creator:
Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Object Type:
Article
System:
The UNT Digital Library
Measurement of the inclusive jet cross section using the k(T) algorithm in p anti-p collisions at s**(1/2) = 1.96-TeV
The authors report on a measurement of the inclusive jet production cross section in p{bar p} collisions at {radical}s = 1.96 TeV using data collected with the upgraded Collider Detector at Fermilab in Run II (CDF II) corresponding to an integrated luminosity of 385 pb{sup -1}. Jets are reconstructed using the k{sub T} algorithm. The measurement is carried out for jets with rapidity 0.1 < |y{sup jet}| < 0.7 and transverse momentum in the range 54 < p{sub T}{sup jet} < 700 GeV/c. The measured cross section is in good agreement with next-to-leading order perturbative QCD predictions after the necessary non-perturbative parton-to-hadron corrections are included.
Date:
December 1, 2005
Creator:
Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Object Type:
Article
System:
The UNT Digital Library
Measurement of the top quark mass with the dynamical likelihood method using lepton plus jets events with b-tags in p anti-p collisions at s**(1/2) = 1.96-TeV
This report describes a measurement of the top quark mass, M{sub top}, with the dynamical likelihood method (DLM) using the CDF II detector at the Fermilab Tevatron. The Tevatron produces top/anti-top (t{bar t}) pairs in p{bar p} collisions at a center-of-mass energy of 1.96 TeV. The data sample used in this analysis was accumulated from March 2002 through August 2004, which corresponds to an integrated luminosity of 318 pb{sup -1}. They use the t{bar t} candidates in the ''lepton+jets'' decay channel, requiring at least one jet identified as a b quark by finding an displaced secondary vertex. The DLM defines a likelihood for each event based on the differential cross section as a function of M{sub top} per unit phase space volume of the final partons, multiplied by the transfer functions from jet to parton energies. The method takes into account all possible jet combinations in an event, and the likelihood is multiplied event by event to derive the top quark mass by the maximum likelihood method. Using 63 t{bar t} candidates observed in the data, with 9.2 events expected from background, they measure the top quark mass to be 173.2{sub -2.4}{sup +2.6}(stat.) {+-} 3.2(syst.) GeV/c{sup 2}, or 173.2{sub -4.0}{sup …
Date:
December 1, 2005
Creator:
Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Object Type:
Article
System:
The UNT Digital Library
Search for anomalous semileptonic decay of heavy flavor hadrons produced in association with a W boson at CDF II
None
Date:
December 1, 2005
Creator:
Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Object Type:
Article
System:
The UNT Digital Library
Search for H ---> b anti-b produced in association with W bosons in p anti-p collisions at s**(1/2) = 1.96-TeV
The authors present a search for the standard model Higgs boson decaying into b{bar b} and produced in association with W bosons in p{bar p} collisions at {radical}s = 1.96 TeV. This search uses 320 pb{sup -1} of the dataset accumulated by the upgraded Collider Detector at Fermilab. Events are selected that have a high-transverse momentum electron or muon, missing transverse energy, and two jets, at least one of which is consistent with the hadronization of a b quark. Both the number of events and the dijet mass distribution are consistent with standard model background expectations, and they set 95% confidence level upper limits on the production cross section times branching ratio for the Higgs boson or any new particle with similar decay kinematics. These upper limits range from 10 pb for m{sub H} = 110 GeV/c{sup 2} to 3 pb for m{sub H} = 150 GeV/c{sup 2}.
Date:
December 1, 2005
Creator:
Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Object Type:
Article
System:
The UNT Digital Library
Search for second-generation scalar leptoquarks in p anti-p collisions at s**(1/2) = 1.96-TeV
None
Date:
December 1, 2005
Creator:
Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Object Type:
Article
System:
The UNT Digital Library
Top quark mass measurement from dilepton events at CDF II
We report a measurement of the top quark mass using events collected by the CDF II Detector from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron. We calculate a likelihood function for the top mass in events that are consistent with t{bar t} {yields} {bar b}{ell}{sup -}{bar {nu}}{sub {ell}}b{ell}{prime}{sup +}{nu}{sub {ell}}{prime} decays. The likelihood is formed as the convolution of the leading-order matrix element and detector resolution functions. The joint likelihood is the product of likelihoods for each of 33 events collected in 340 pb{sup -1} of integrated luminosity, yielding a top quark mass M{sub t} = 165.2 {+-} 6.1(stat.) {+-} 3.4(syst.) GeV/c{sup 2}. This first application of a matrix-element technique to t{bar t} {yields} b{ell}{sup +}{nu}{sub {ell}}{bar b}{ell}{prime}{sup -}{bar {nu}}{sub {ell}}, decays gives the most precise single measurement of M{sub t} in dilepton events. Combined with other CDF Run II measurements using dilepton events, we measure M{sub t} = 167.9 {+-} 5.2(stat.) {+-} 3.7(syst.) GeV/c{sup 2}.
Date:
December 1, 2005
Creator:
Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Object Type:
Article
System:
The UNT Digital Library
A Search for scalar bottom quarks from gluino decays in anti-p p collisions at s**(1/2) = 1.96-TeV
We searched for scalar bottom quarks in 156 pb{sup -1} of {bar p}p collisions at {radical}s = 1.96 TeV recorded by the CDF II experiment at the Tevatron. Scalar bottom quarks can be produced from gluino decays in R-parity conserving models of supersymmetry when the mass of the gluino exceeds that of the scalar bottom quark. Then, a scalar bottom quark can decay into a bottom quark and a neutralino. To search for this scenario, we investigated events with large missing transverse energy and at least three jets, two or more of which were identified as containing a secondary vertex from the hadronization of b quarks. We found four candidate events, where 2.6 {+-} 0.7 are expected from standard model processes, and placed 95% confidence level lower limits on gluino and scalar bottom quark masses of up to 280 and 240 GeV/c{sup 2} , respectively.
Date:
December 1, 2005
Creator:
Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M.G. et al.
Object Type:
Article
System:
The UNT Digital Library
Monitoring the Migrations of Wild Snake River Spring/Summer Chinook Salmon Juveniles, 2003-2004 Annual Report.
This report provides information on PIT-tagging of wild Chinook salmon parr in Idaho in 2003 and the subsequent monitoring of these fish and similarly tagged fish from Oregon. We report estimated parr-to-smolt survival and arrival timing of these fish at Lower Granite Dam, as well as interrogation data collected at several other sites throughout the Snake and Columbia River system. This research continues studies that began under Bonneville Power Administration (BPA) funding in 1991. Results from previous study years were reported by Achord et al. (1994; 1995a,b; 1996a; 1997; 1998; 2000; 2001a,b; 2002, 2003, 2004). Goals of this ongoing study are: (1) Characterize the migration timing and estimate parr-to-smolt survival of different stocks of wild Snake River spring/summer Chinook salmon smolts at Lower Granite Dam. (2) Determine whether consistent migration patterns are apparent. (3) Determine what environmental factors influence migration patterns. (4) Characterize the migration behavior and estimate survival of different wild juvenile fish stocks as they emigrate from their natal rearing areas. This study provides critical information for recovery planning, and ultimately recovery for these ESA-listed wild fish stocks. In 2003-2004, we also continued to measure water temperature, dissolved oxygen, specific conductance, turbidity, water depth, and pH at five …
Date:
June 1, 2005
Creator:
Achord, Stephen; Hodge, Jacob M. & Sandford, Benjamin P.
Object Type:
Report
System:
The UNT Digital Library
The Role of Global Observations for Climate and Other Applications
Most of the current earth-observing systems have been designed primarily for the needs of weather forecasting. Weather forecasting is an initial condition problem; the success of the forecast is heavily dependent on the quality of the specified initial state of the atmosphere. Thus, weather forecasting observing systems tend to focus on determining the 3D values of the state variables of the system namely temperature, humidity, and wind vector. While weather forecasting requires accurate observations, spatial patterns and relative accuracy across those patterns are the primary concern. Climate, on the other hand, is a boundary condition problem, i.e., climate simulation depends on knowing the energy fluxes into and out of the system, and quantities such as CO2 that affect the flow of those energy fluxes in the system. Consequently, climate-observing systems must extend beyond measurements of state variables to flux measurements of radiation energy and water. We focus on these two cycles because the dominant forms of energy transfer in the climate system (solar energy, thermal infrared energy, evaporation, and condensation) involve these two quantities. Further, because climate is a search for small system trends and imbalances in the midst of large weather variability, climate observations require a much higher degree …
Date:
May 1, 2005
Creator:
Ackerman, T.P.
Object Type:
Report
System:
The UNT Digital Library
The Role of Global Observations for Climate and Other Applications
Most of the current earth-observing systems have been designed primarily for the needs of weather forecasting. Weather forecasting is an initial condition problem; the success of the forecast is heavily dependent on the quality of the specified initial state of the atmosphere. Thus, weather forecasting observing systems tend to focus on determining the 3D values of the state variables of the system – namely temperature, humidity, and wind vector. While weather forecasting requires accurate observations, spatial patterns and relative accuracy across those patterns are the primary concern. Climate, on the other hand, is a boundary condition problem, i.e., climate simulation depends on knowing the energy fluxes into and out of the system, and quantities such as CO2 that affect the flow of those energy fluxes in the system. Consequently, climate-observing systems must extend beyond measurements of state variables to flux measurements of radiation energy and water. We focus on these two cycles because the dominant forms of energy transfer in the climate system (solar energy, thermal infrared energy, evaporation, and condensation) involve these two quantities. Further, because climate is a search for small system trends and imbalances in the midst of large weather variability, climate observations require a much higher …
Date:
May 1, 2005
Creator:
Ackerman, TP
Object Type:
Report
System:
The UNT Digital Library
# top physics: measurement of the ttbar production cross section in pp-bar collisions at sqrt s = 1.96 tev using lepton plus jets events with semileptonic b decays to muons
We present a measurement of the t{bar t} production cross section using 194 pb{sup -1} of CDF II data using events with a high transverse momentum electron or muon, three or more jets, and missing transverse energy. The measurement assumes 100% t {yields} Wb branching fraction. Events consistent with t{bar t} decay are found by identifying jets containing heavy flavor semileptonic decays to muons. The dominant backgrounds are evaluated directly from the data. Based on 20 candidate events and an expected background of 9.5 {+-} 1.1 events, we measure a production cross section of 5.3 {+-} 3.3{sub -1.0}{sup +1.3} pb, in agreement with the standard model.
Date:
June 1, 2005
Creator:
Acosta, D.
Object Type:
Report
System:
The UNT Digital Library