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Articles 1 - 20 of 20
Full-Text Articles in Physical Sciences and Mathematics
Uncertainty In Recharge From Subsidence Craters At Frenchman Flat, Nevada Test Site: Impacts Of Initial And Boundary Conditions And Media Properties, David Matthew Ely
Uncertainty In Recharge From Subsidence Craters At Frenchman Flat, Nevada Test Site: Impacts Of Initial And Boundary Conditions And Media Properties, David Matthew Ely
UNLV Theses, Dissertations, Professional Papers, and Capstones
The Nevada Test Site has over 400 subsidence craters formed by the collapse of overlying rock following underground nuclear tests. Under natural conditions, infiltration and recharge would not be considered likely due to infrequent precipitation events and extreme evapotranspiration. Crater U5a in Frenchman Flat was chosen for study because it intercepts significantly more drainage than surrounding craters. Vadose zone modeling was conducted to test the sensitivity of water movement to boundary and initial conditions. The effects of ponding depth was negligible but depth of wetting front movement was highly dependent on the lateral extent of the ponds. The model was …
Photofragmentation Of Third-Row Hydrides Following Photoexcitation At Deep-Core Levels, D. L. Hansen, M. E. Arrasate, J. Cotter, G. R. Fisher, Oliver Hemmers, K. T. Leung, Jon C. Levin, R. Martin, Paul Neill, Rupert C. Perera, I. A. Sellin, Marc Simon, Y. Uehara, B. Vanderford, S. B. Whitfield, Dennis W. Lindle
Photofragmentation Of Third-Row Hydrides Following Photoexcitation At Deep-Core Levels, D. L. Hansen, M. E. Arrasate, J. Cotter, G. R. Fisher, Oliver Hemmers, K. T. Leung, Jon C. Levin, R. Martin, Paul Neill, Rupert C. Perera, I. A. Sellin, Marc Simon, Y. Uehara, B. Vanderford, S. B. Whitfield, Dennis W. Lindle
X-Ray Atomic and Molecular Science Program
The relaxation dynamics of HCl, DCl, H2S, and D2S following photoexcitation in the vicinities of the Cl and S K-shell thresholds (~2.8 keV for Cl, ~2.5 keV for S) were studied by means of ion time-of-flight mass spectroscopy. In all cases, the onset of pre-edge core-shell photoionization precedes the formation on resonance of a significant amount of neutral hydrogen as well as postcollision-interaction effects above threshold. Examination of the width of the H+ peak in spectra taken with the analyzer parallel and perpendicular to the polarization vector of the incident light indicates that on resonance, …
Photofragmentation Of Third-Row Hydrides Following Photoexcitation At Deep-Core Levels, D. Hansen, M. E. Arrasate, J. Cotter, G. R. Fisher, Oliver Hemmers, K. T. Leung, Jon C. Levin, R. Martin, Paul Neill, Rupert C. Perera, I. A. Sellin, Marc Simon, Y. Uehara, B. Vanderford, S. B. Whitfield, Dennis W. Lindle
Photofragmentation Of Third-Row Hydrides Following Photoexcitation At Deep-Core Levels, D. Hansen, M. E. Arrasate, J. Cotter, G. R. Fisher, Oliver Hemmers, K. T. Leung, Jon C. Levin, R. Martin, Paul Neill, Rupert C. Perera, I. A. Sellin, Marc Simon, Y. Uehara, B. Vanderford, S. B. Whitfield, Dennis W. Lindle
Environmental Studies Faculty Publications
The relaxation dynamics of HCl, DCl, H2S, and D2S following photoexcitation in the vicinities of the Cl and S K-shell thresholds (∼2.8keV for Cl, ∼2.5 keV for S) were studied by means of ion time-of-flight mass spectroscopy. In all cases, the onset of pre-edge core-shell photoionization precedes the formation on resonance of a significant amount of neutral hydrogen as well as postcollision-interaction effects above threshold. Examination of the width of the H+ peak in spectra taken with the analyzer parallel and perpendicular to the polarization vector of the incident light indicates that on resonance, the …
High-Resolution Electron Time-Of-Flight Apparatus For The Soft-X-Ray Region, Oliver Hemmers, S. B. Whitfield, P. Glans, H. Wang, Dennis W. Lindle, R. Wehlitz, I. A. Sellin
High-Resolution Electron Time-Of-Flight Apparatus For The Soft-X-Ray Region, Oliver Hemmers, S. B. Whitfield, P. Glans, H. Wang, Dennis W. Lindle, R. Wehlitz, I. A. Sellin
Environmental Studies Faculty Publications
A gas-phase time-of-flight (TOF) apparatus, capable of supporting as many as six electron-TOF analyzers viewing the same interaction region, has been developed to measure energy- and angle-resolved electrons with kinetic energies up to 5 keV. Each analyzer includes a newly designed lens system that can retard electrons to about 2% of their initial kinetic energy without significant loss of transmission; the analyzers can thus achieve a resolving power (E/ΔE) greater than 104 over a wide kinetic-energy range. Such high resolving power is comparable to the photon energy resolution of state-of-the-art synchrotron–radiation beamlines in the soft …
Vegetation Analysis: A Graphical Analysis Of Plant Succession In Desert Communities Affected By Fire, Jeff Lantow
Vegetation Analysis: A Graphical Analysis Of Plant Succession In Desert Communities Affected By Fire, Jeff Lantow
UNLV Theses, Dissertations, Professional Papers, and Capstones
The Mojave Desert is affected by fire every year. With each fire comes the removal of old growth and, in its place, new growth – consisting primarily of those species which thrive in disturbed areas. The focus of my research is to look at plant communities that have been disturbed by fire, and examine the successional pathway of these disturbed environments. The seven environments I analyzed were burned within the last twenty years and are found in the Coleogyne ramosissima ecotone throughout the Spring Mountain range near Las Vegas, Nevada. The data was collected with randomly chosen circle plots in …
Water Conservation In The Las Vegas Valley, Judith M. Keir
Water Conservation In The Las Vegas Valley, Judith M. Keir
UNLV Theses, Dissertations, Professional Papers, and Capstones
This thesis deals primarily with residential use of water in the Las Vegas Valley, an arid climate located in the Mojave Desert, and whether the education of people living here has any bearing on whether or not they conserve water. Many of the residents of the Las Vegas Valley have moved from other areas of the country, and perhaps are not aware of the fact that there is a limited supply of water available to the Valley. I believe that people are not necessarily wasteful, and that they would want to conserve water, if they were aware that conservation and …
Lead Shot Concentration In Soil At The Overton Wildlife Management Area, Nevada, George R. Bertoty
Lead Shot Concentration In Soil At The Overton Wildlife Management Area, Nevada, George R. Bertoty
UNLV Theses, Dissertations, Professional Papers, and Capstones
During the spring of 1998, soil samples were collected from two areas at the Overton Wildlife Management Area (OWMA), located in the Moapa Valley of Clark County, Nevada. Lead shot has been banned for the hunting of waterfowl since 1986 but is still legal for upland game hunting. Both types of hunting occur at OWMA. One area sampled is a cultivated field and serves primarily as a dove hunting area. The other area is primarily a waterfowl hunting area and is flooded during the waterfowl-hunting season. Lead shot was recovered from 83% of the samples from the dove hunting area, …
A Strategic Analysis Of The Rocky Flats Cleanup, Patrick Mccann
A Strategic Analysis Of The Rocky Flats Cleanup, Patrick Mccann
UNLV Theses, Dissertations, Professional Papers, and Capstones
The Rocky Flats Environmental Technology Site is located in Golden, Colorado. It is situated on 384 acres in a 6,550-acre natural preserve. Rocky Flats ended its original mission in 1989, after raids on the site by both the FBI and the EPA for illegal dumping and other environmental violations. Since then the site has been scheduled for cleanup. This thesis will provide background information on the site and on the company hired to perform the cleanup. It also provides an evaluation of some key policies regarding the cleanup procedures. Since the end of the cold war, the production of nuclear …
Interagency Lake Mead And Las Vegas Wash Monitoring Program: Standard Operating Procedures Manual, Bureau Of Reclamation, City Of Henderson Water Reclamation Facility, City Of Las Vegas Water Pollution Control Facility, Clark County Sanitation District, Nevada, Southern Nevada Water Authority
Interagency Lake Mead And Las Vegas Wash Monitoring Program: Standard Operating Procedures Manual, Bureau Of Reclamation, City Of Henderson Water Reclamation Facility, City Of Las Vegas Water Pollution Control Facility, Clark County Sanitation District, Nevada, Southern Nevada Water Authority
Publications (WR)
A number of agencies sample Lake Mead and the Las Vegas Wash on a routine basis at several locations. In order to share and properly interpret the data, the Bureau of Reclamation, Southern Nevada Water Authority and the three Wastewater Treatment Facilities (City of Las Vegas, Clark County Sanitation District and City of Henderson) formed a committee to examine sampling and analytical protocols and to share information with the goal of maximizing the data quality. The group first met in April 1997.
It was agreed that an effort should be made to discuss and compare specific sampling and analytical techniques …
Validation Of Waimss Incident Duration Estimation Model, Wei Wu, Pushkin Kachroo, Kaan Ozbay
Validation Of Waimss Incident Duration Estimation Model, Wei Wu, Pushkin Kachroo, Kaan Ozbay
Electrical & Computer Engineering Faculty Research
This paper presents an effort to validate the traffic incident duration estimation model of WAIMSS (wide area incident management support system). Duration estimation model of WAIMSS predicts the incident duration based on an estimation tree which was calibrated using incident data collected in Northern Virginia. Due to the limited sample size, a full scale test of the distribution, mean and variance of incident duration was performed only for the root node of the estimation tree, white only mean tests were executed at all other nodes whenever a data subset was available. Further studies were also conducted on the model error …
Wide-Area Incident Management System On The Internet, Kaan Ozbay, Pushkin Kachroo
Wide-Area Incident Management System On The Internet, Kaan Ozbay, Pushkin Kachroo
Electrical & Computer Engineering Faculty Research
The incident management process consists of four sequential steps-incident detection, response, clearance and recovery. Each of these components comprises of a number of operations and coordinated decision-making between the agencies involved. The provision of computer based support tools for the personnel involved will help develop appropriate strategies and increase efficiency and expediency. Existing systems are developed on various traditional computing platforms. However, with the advent of World Wide Web and Internet based programming tools such as Java, it is now possible to develop platform independent decision support tools for the incident management agencies. Any agency will be able to use …
Auger Resonance Decay Process In Ar 2p Shell Excitation And Ionization, Y. Lu, Wayne C. Stolte, J.A. R. Samson
Auger Resonance Decay Process In Ar 2p Shell Excitation And Ionization, Y. Lu, Wayne C. Stolte, J.A. R. Samson
Chemistry and Biochemistry Faculty Research
The production and subsequent autoionization of the Ar+ (1D2)6d1 satellite state that is formed either by shake-up or recapture during the Auger decay of a 2p vacancy in Ar has been studied by photoelectron spectroscopy in the energy region from 243 to 256 eV. The creation of near zero energy electrons below and immediately above the Ar 2p ionization threshold is discussed. Some ambiguous points in previous studies are clarified.
Stachybotrys: Is Nevada At Risk?, Terrylynn C. Foley
Stachybotrys: Is Nevada At Risk?, Terrylynn C. Foley
UNLV Theses, Dissertations, Professional Papers, and Capstones
Stachybotrys chartarum (atra) is a toxigenic fungus that is known to adversely impact the health of animals. Until recently, there have only been a few documented clinical reports linking Stachybotrys chartarum to human health effects. Scientists are increasingly convinced that Stachybotrys and its metabolites are responsible for several adverse health effects experienced by people all over the world, although conclusive proof has yet to be established. All the physical requirements needed for indoor Stachybotrys sporulation and growth is provided through water leaks (plumbing, roof or ceiling), flood events, nutrient sources (cellulose and nitrogen), pH, and temperature(23° - 28°C). Stachybotrys has …
A Teachers Guide: The Basic Characteristics Of Wetlands And Why They Are Important To The Environment, Charles W. Fisher
A Teachers Guide: The Basic Characteristics Of Wetlands And Why They Are Important To The Environment, Charles W. Fisher
UNLV Theses, Dissertations, Professional Papers, and Capstones
The purpose of this thesis is to develop an educational guide about wetlands that can be used by 3rd- 12th grade teachers. This guide will enable students to learn about wetlands and why they are important to our environment. I will provide examples and a series of activities that teachers can use in the classroom to help their students better understand the benefits and function of wetlands.
The Price Of Clean Air: A Consideration Of Market Based Emissions Trading, Mark W. Miller
The Price Of Clean Air: A Consideration Of Market Based Emissions Trading, Mark W. Miller
UNLV Theses, Dissertations, Professional Papers, and Capstones
Traditional regulatory approaches for environmental protection do not consider
the costs and benefits of the standards they impose. Further, imposing strict performance
standards on firms with heterogeneous control costs leads to an inefficient allocation of resources devoted to pollution control. This paper explores the use of emission allowance trading as a way to improve economic efficiency within the context of environmental protection. PM10 air pollution from sources within the Las Vegas Valley is used as the case study.
This paper found that an emission trading
program in this particular case study would not live up to the theoretical expectations. Although, …
Effects Of Oxygen Variation On The Ecology Of Devil's Hole, Death Valley National Park, Norma J. Azad
Effects Of Oxygen Variation On The Ecology Of Devil's Hole, Death Valley National Park, Norma J. Azad
UNLV Theses, Dissertations, Professional Papers, and Capstones
The inability to rear Devil's Hole pupfish, Cyprinodon diabolis Wales, in captivity, when captive propagation has been successful with other species of pupfish, led to the examination of environmental factors which are unique to Devil's Hole. It has been suggested that C. diabolis regularly experience developmental arrest due to hypoxic conditions. This arrest may be reversible in areas of the shallow shelf during periods of photosynthetic activity. Oxygen measurements over the shallow shelf reveal a gradient of oxygen variation with the greatest diel variability over the inner portion of the shelf diminishing to nearly imperceptible diel variation toward the outer …
Watercraft Impact On The Lake Mead National Recreational Area, Terence Lino
Watercraft Impact On The Lake Mead National Recreational Area, Terence Lino
UNLV Theses, Dissertations, Professional Papers, and Capstones
No abstract provided.
A Comparison Of Astm Standard E1599-94 And A Site Assessment Project Located In North Las Vegas, Kenneth Anthony Katsuda
A Comparison Of Astm Standard E1599-94 And A Site Assessment Project Located In North Las Vegas, Kenneth Anthony Katsuda
UNLV Theses, Dissertations, Professional Papers, and Capstones
This document provides a comparison of ASTM E-1599-94 Standard for a petroleum release and the procedures performed on a site assessment project in North Las Vegas. The major elements of a site assessment are thoroughly discussed in this document. They elements consist of the Initial Site Assessment, On-Site Delineation, Off-Site Delineation, Sampling/Analysis, and Site Assessment Methodologies.
The data was obtained through extensive research, utilizing reference documents,on-site experience, and the knowledge of Keith Stewart of Stewart Environmental.
After reviewing and comparing the data of my research, the procedures applied to the North Las Vegas Site (NLVS) were quite similar to the …
Neutral Dissociation Of Hydrogen Following Photoexcitation Of Hcl At The Chlorine K Edge, D. L. Hansen, J. Cotter, G. R. Fisher, K. T. Leung, R. Martin, Paul Neill, Rupert C. Perera, I. A. Sellin, Marc Simon, Y. Uehara, B. Vanderford, S. B. Whitfield
Neutral Dissociation Of Hydrogen Following Photoexcitation Of Hcl At The Chlorine K Edge, D. L. Hansen, J. Cotter, G. R. Fisher, K. T. Leung, R. Martin, Paul Neill, Rupert C. Perera, I. A. Sellin, Marc Simon, Y. Uehara, B. Vanderford, S. B. Whitfield
Chemistry and Biochemistry Faculty Research
Time-of-flight mass spectroscopy was used to study the relaxation dynamics of HCl following photoexcitation in the vicinity of the Cl K edge (~2.8 keV) using monochromatic synchrotron radiation. At the lowest resonant excitation to the 6ơ* antibonding orbital, almost half of the excited molecules decay by emission of a neutral H atom, mostly in coincidence with a highly charged Cln1 ion. The present work demonstrates that neutral-atom emission can be a significant decay channel for excited states with very short lifetimes (1 fs). [S1050-2947(98)03604-X]
Double Photoionization Of Helium, James A.R. Samson, Wayne C. Stolte, Z. X. He, Y. Lu, J. N. Cutler, R. J. Bartlett
Double Photoionization Of Helium, James A.R. Samson, Wayne C. Stolte, Z. X. He, Y. Lu, J. N. Cutler, R. J. Bartlett
Chemistry and Biochemistry Faculty Research
The cross sections for double photoionization of helium and the ratios of double to single ionization have been measured from the double-ionization threshold to 820 eV. The results are in very good agreement with several recent calculations.