Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

2007

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 1 - 30 of 6135

Full-Text Articles in Physical Sciences and Mathematics

Diaphragm And Lubricant Gel For Prevention Of Hiv Acquisition In Southern African Women: A Randomised Controlled Trial, Nancy Padian, Ariane Van Der Straten, Gita Ramjee, Tsungai Chipato, Guy De Bruyn, Kelly Blanchard, Stephen Shiboski, Elizabeth Montgomery, Heidi Fancher, Helen Cheng, Michael Rosenblum, Mark Van Der Laan, Nicholas Jewell, James Mcintyre Dec 2015

Diaphragm And Lubricant Gel For Prevention Of Hiv Acquisition In Southern African Women: A Randomised Controlled Trial, Nancy Padian, Ariane Van Der Straten, Gita Ramjee, Tsungai Chipato, Guy De Bruyn, Kelly Blanchard, Stephen Shiboski, Elizabeth Montgomery, Heidi Fancher, Helen Cheng, Michael Rosenblum, Mark Van Der Laan, Nicholas Jewell, James Mcintyre

Michael Rosenblum MD

Background Female-controlled methods of HIV prevention are urgently needed. We assessed the effect of provision of latex diaphragm, lubricant gel, and condoms (intervention), compared with condoms alone (control) on HIV seroincidence in women in South Africa and Zimbabwe. Methods We did an open-label, randomised controlled trial in HIV-negative, sexually active women recruited from clinics and community-based organisations, who were followed up quarterly for 12—24 months (median 21 months). All participants received an HIV prevention package consisting of pre-test and post-test counselling about HIV and sexually transmitted infections, testing, treatment of curable sexually transmitted infections, and intensive risk-reduction counselling. The ...


Biological, Clinical, And Forensic Analysis Using Comprehensive Two-Dimensional Gas Chromatography, Nicholas Snow Jun 2015

Biological, Clinical, And Forensic Analysis Using Comprehensive Two-Dimensional Gas Chromatography, Nicholas Snow

Nicholas A Snow

No abstract provided.


Distribution And Transport Of Coal Tar-Derived Pahs In Fine-Grained Residuum, Vijay Vulava, Larry Mckay, Steven Driese, Fu-Min Menn, Gary Sayler Jun 2013

Distribution And Transport Of Coal Tar-Derived Pahs In Fine-Grained Residuum, Vijay Vulava, Larry Mckay, Steven Driese, Fu-Min Menn, Gary Sayler

Gary S. Sayler

We investigated the distribution and transport of coal tar-derived polycyclic aromatic hydrocarbons (PAHs) in fine-grained residuum and alluvial floodplain deposits that underlie a former manufactured gas plant. All 16 USEPA priority pollutant PAHs are present at this site and have penetrated the entire 4–5 m thickness of clayey sediments, which unconformably overly limestone bedrock. Concentrations of less hydrophobic PAHs (e.g., naphthalene, 0.011–384 mg kg−1) were about 10 times higher than those of highly hydrophobic PAHs (e.g., benzo[g, h, i]perylene −0.002 to 56.03 mg kg−1). Microscopic examination of thin-sections of ...


Humancentric Applications Of Rfid Chips, S. Derrick, K. Michael, H. Tootell Dec 2012

Humancentric Applications Of Rfid Chips, S. Derrick, K. Michael, H. Tootell

Dr Holly Tootell

No abstract provided.


Metal Modulation Epitaxy Growth For Extremely High Hole Concentrations Above 10(19) Cm(-3) In Gan, Gon Namkoong, Elaissa Trybus, Kyung Keun Lee, Michael Moseley, W. Alan Doolittle, David C. Look Dec 2007

Metal Modulation Epitaxy Growth For Extremely High Hole Concentrations Above 10(19) Cm(-3) In Gan, Gon Namkoong, Elaissa Trybus, Kyung Keun Lee, Michael Moseley, W. Alan Doolittle, David C. Look

Applied Research Center Publications

The free hole carriers in GaN have been limited to concentrations in the low 1018 cm−3 range due to the deep activation energy, lower solubility, and compensation from defects, therefore, limiting doping efficiency to about 1%. Herein, we report an enhanced doping efficiency up to ~10% in GaN by a periodic doping, metal modulation epitaxy growth technique. The hole concentrations grown by periodically modulating Ga atoms and Mg dopants were over ~1.5 x 1019 cm−3.

© 2008 American Institute of Physics.


Unit Rectangle Visibility Graphs, Alice M. Dean, Joanna A. Ellis-Monaghan, Sarah J. Hamilton, Greta Pangborn Dec 2007

Unit Rectangle Visibility Graphs, Alice M. Dean, Joanna A. Ellis-Monaghan, Sarah J. Hamilton, Greta Pangborn

Mathematics, Statistics and Computer Science Faculty Research and Publications

Over the past twenty years, rectangle visibility graphs have generated consider- able interest, in part due to their applicability to VLSI chip design. Here we study unit rectangle visibility graphs, with fixed dimension restrictions more closely modeling the constrained dimensions of gates and other circuit components in computer chip applications. A graph G is a unit rectangle visibility graph (URVG) if its vertices can be represented by closed unit squares in the plane with sides parallel to the axes and pairwise disjoint interiors, in such a way that two vertices are adjacent if and only if there is a non-degenerate ...


Muon-Fluorine Entangled States In Molecular Magnets, T Lancaster, S J. Blundell, P J. Baker, M L. Brooks, W Hayes, F L. Pratt, Jamie L. Manson, M M. Conner, J A. Schlueter Dec 2007

Muon-Fluorine Entangled States In Molecular Magnets, T Lancaster, S J. Blundell, P J. Baker, M L. Brooks, W Hayes, F L. Pratt, Jamie L. Manson, M M. Conner, J A. Schlueter

Chemistry and Biochemistry Faculty Publications

The information accessible from a muon-spin relaxation experiment can be limited due to a lack of knowledge of the precise muon stopping site. We demonstrate here the possibility of localizing a spin polarized muon in a known stopping state in a molecular material containing fluorine. The muon-spin precession that results from the entangled nature of the muon spin and surrounding nuclear spins is sensitive to the nature of the stopping site. We use this property to identify three classes of sites that occur in molecular magnets and describe the extent to which the muon distorts its surroundings.


Nevada Interagency Volunteer Program: Helping Hands Across Public Lands – Phase Ii: Quarterly Progress Report, Period Covering October 1 – December 31, 2007, Margaret N. Rees Dec 2007

Nevada Interagency Volunteer Program: Helping Hands Across Public Lands – Phase Ii: Quarterly Progress Report, Period Covering October 1 – December 31, 2007, Margaret N. Rees

Get Outdoors Nevada

  • The number of records in the volunteer database increased 12% over last quarter. The database now contains 4,937 records.
  • Website activity decreased, recording an average of 82,859 hits per month, a decrease of 31% from last quarter, with an average of 8,191 pages viewed per month.
  • Volunteer fall training has been completed.
  • Three National Public Land Day Events have been completed.
  • Two hundred and ten people attended the Volunteer Recognition Event.


Interagency Science And Research: Quarterly Progress Report, Period Ending December 31, 2007, Margaret N. Rees Dec 2007

Interagency Science And Research: Quarterly Progress Report, Period Ending December 31, 2007, Margaret N. Rees

Interagency Science and Research Strategy

  • Meetings were held with the SNAP Recreation Team and the SNAP Cultural Resources Team to request assistance in the development of the science strategy. Draft versions of interagency goals, subgoals, science questions, and associated tasks were given to each team for review and input.
  • Plans were prepared for the peer review of science proposals submitted for consideration as Conservations Initiatives in SNPLMA Round 9.
  • Proceedings of the natural resources management workshop held on September 13 were completed and sent to the Science & Research Team for review by members.
  • An important focus of the Science and Research Team was the development ...


Lake Mead National Recreation Area Vegetation Monitoring And Management: Quarterly Progress Report, October 1, 2007 To December 31, 2007, Margaret N. Rees Dec 2007

Lake Mead National Recreation Area Vegetation Monitoring And Management: Quarterly Progress Report, October 1, 2007 To December 31, 2007, Margaret N. Rees

Vegetation Monitoring

Executive Summary

  • The Weed Sentry program surveyed more than 750 miles of federal lands in Clark County for invasive, exotic plant species.
  • Weed Sentry also removed more than 600,000 individual invasive plants from federal
    lands. These removals represent pro-active efforts that may have forestalled large
    infestations difficult and costly to eradicate.
  • In response to a request by the manager of the Fish and Wildlife Service Desert National
    Wildlife Refuge, a major effort of surveying springs for plant community composition
    and invasive plants provided unique knowledge services by the Weed Sentry program.
    No such baseline information existed for the Sheep ...


Lake Mead National Recreation Area Sensitive Wildlife Species Monitoring And Analysis: Quarterly Progress Report, Period Ending December 31, 2007, Margaret N. Rees Dec 2007

Lake Mead National Recreation Area Sensitive Wildlife Species Monitoring And Analysis: Quarterly Progress Report, Period Ending December 31, 2007, Margaret N. Rees

Wildlife Monitoring

Project 1. Relict Leopard Frog Monitoring, Management, and Research

  • Fall surveys completed at all natural and translocation sites.
  • Coordination for a potential translocation site on BLM lands in the Gold Butte area ongoing – the aim is that this site will be ready for translocations in 2008.
  • Coordination ongoing for evaluation of a translocation site on BLM lands in the Black Mountains, AZ – the plan is to complete compliance in 2008.
  • Coordination and assistance provided to UNLV research efforts on habitat improvements at Blue Point, Rogers, and Pupfish Refuge springs.
  • Relict Leopard Frog Conservation Team meeting held in December.
  • Draft annual ...


Limnological Assistance For The Lake Mead National Recreation Area In Meeting The Challenge Of The Water 2025 Initiative: Quarterly Progress Report, Period Ending: December 1, 2007, Margaret N. Rees Dec 2007

Limnological Assistance For The Lake Mead National Recreation Area In Meeting The Challenge Of The Water 2025 Initiative: Quarterly Progress Report, Period Ending: December 1, 2007, Margaret N. Rees

Limnological Studies

  • The limnologist position has been announced.
  • Project 1: Review of the draft Boulder Basin Adaptive Management Plan is underway.
  • Project 2: Development of a white paper expressing the joint needs of the entities involved in Water 2025 projects is being coordinated.
  • Project 3: A bibliographic reference spreadsheet organizing literature citations related to quagga and zebra mussel research has been completed.
  • Project 4: A comprehensive literature search of Lake Mead limnology is well underway; an Access database has been designed to organize reference citations; and a special collections library at UNLV is being established to house original rare documents and other ...


Masthead Dec 2007

Masthead

Journal of Digital Forensics, Security and Law

No abstract provided.


Back Matter Dec 2007

Back Matter

Journal of Digital Forensics, Security and Law

No abstract provided.


Numerical Approximations Of Differential Equations And Applications In Maple, Joyce Zimmerman Dec 2007

Numerical Approximations Of Differential Equations And Applications In Maple, Joyce Zimmerman

Masters Theses

No abstract provided.


Front Matter Dec 2007

Front Matter

Journal of Digital Forensics, Security and Law

No abstract provided.


Casimir Effect In Quantum Physics, Matthew James Urfer Dec 2007

Casimir Effect In Quantum Physics, Matthew James Urfer

Masters Theses

No abstract provided.


Thermal Conductivity And Particle Agglomeration In Alumina Nanofluids: Experiment And Theory, Jonathan Selinger, Elena V. Timofeeva, Alexei N. Gavrilov, James M. Mccloskey, Yuriy V. Tolmachev Dec 2007

Thermal Conductivity And Particle Agglomeration In Alumina Nanofluids: Experiment And Theory, Jonathan Selinger, Elena V. Timofeeva, Alexei N. Gavrilov, James M. Mccloskey, Yuriy V. Tolmachev

Chemical Physics Publications

In recent years many experimentalists have reported an anomalously enhanced thermal conductivity in liquid suspensions of nanoparticles. Despite the importance of this effect for heat transfer applications, no agreement has emerged about the mechanism of this phenomenon, or even about the experimentally observed magnitude of the enhancement. To address these issues, this paper presents a combined experimental and theoretical study of heat conduction and particle agglomeration in nanofluids. On the experimental side, nanofluids of alumina particles in water and ethylene glycol are characterized using thermal conductivity measurements, viscosity measurements, dynamic light scattering, and other techniques. The results show that the ...


Theory And Numerics Of Gravitational Waves From Preheating After Inflation, Jean-François Dufaux, Amanda Bergman, Gary Felder, Lev Kofman, Jean-Philippe Uzan Dec 2007

Theory And Numerics Of Gravitational Waves From Preheating After Inflation, Jean-François Dufaux, Amanda Bergman, Gary Felder, Lev Kofman, Jean-Philippe Uzan

Physics: Faculty Publications

Preheating after inflation involves large, time-dependent field inhomogeneities, which act as a classical source of gravitational radiation. The resulting spectrum might be probed by direct detection experiments if inflation occurs at a low enough energy scale. In this paper, we develop a theory and algorithm to calculate, analytically and numerically, the spectrum of energy density in gravitational waves produced from an inhomogeneous background of stochastic scalar fields in an expanding universe. We derive some generic analytical results for the emission of gravity waves by stochastic media of random fields, which can test the validity/accuracy of numerical calculations. We contrast ...


Extending The Information Partition Function: Modeling Interaction Effects In Highly Multivariate, Discrete Data, Paul C. Cannon Dec 2007

Extending The Information Partition Function: Modeling Interaction Effects In Highly Multivariate, Discrete Data, Paul C. Cannon

All Theses and Dissertations

Because of the huge amounts of data made available by the technology boom in the late twentieth century, new methods are required to turn data into usable information. Much of this data is categorical in nature, which makes estimation difficult in highly multivariate settings. In this thesis we review various multivariate statistical methods, discuss various statistical methods of natural language processing (NLP), and discuss a general class of models described by Erosheva (2002) called generalized mixed membership models. We then propose extensions of the information partition function (IPF) derived by Engler (2002), Oliphant (2003), and Tolley (2006) that will allow ...


Ontology Learning For The Semantic Deep Web, Yoo Jung An Dec 2007

Ontology Learning For The Semantic Deep Web, Yoo Jung An

Dissertations

Ontologies could play an important role in assisting users in their search for Web pages. This dissertation considers the problem of constructing natural ontologies that support users in their Web search efforts and increase the number of relevant Web pages that are returned. To achieve this goal, this thesis suggests combining the Deep Web information, which consists of dynamically generated Web pages and cannot be indexed by the existing automated Web crawlers, with ontologies, resulting in the Semantic Deep Web. The Deep Web information is exploited in three different ways: extracting attributes from the Deep Web data sources automatically, generating ...


The Development And Evaluation Of Software To Foster Professional Development In Educational Assessment, Morgan C. Benton Dec 2007

The Development And Evaluation Of Software To Foster Professional Development In Educational Assessment, Morgan C. Benton

Dissertations

This dissertation sought to answer the question: Is it possible to build a software tool that will allow teachers to write better multiple-choice questions? The thesis proceeded from the finding that the quality of teaching is very influential in the amount that students learn. A basic premise of this research, then, is that improving teachers will improve learning. With this foundation, the next question became what area of teaching to improve. The literature on educational assessment indicated that teachers lack competence at effective assessment, particularly in the area of multiple-choice question generation. It is likely that improvement in this area ...


User Evaluation Of The Performance Of Information Systems, Edward Mahinda Dec 2007

User Evaluation Of The Performance Of Information Systems, Edward Mahinda

Dissertations

Information technologies (IT) are considered the primary survival factor for many organizations and the most critical success factor in businesses today. To justify the necessary investment in IT, user evaluation of information systems' performance in organizations is a key consideration. This research investigated a comprehensive and convenient means for end users to assess this performance.

Among the existing theories and models on the evaluation of information system performance based on intrinsic technological properties, the Web of System Performance (WOSP) model provides the most comprehensive basis for information system evaluation, and therefore merited further investigation. The research question was how well ...


Complex Adaptive Systems Based Data Integration : Theory And Applications, Eliahu Rohn Dec 2007

Complex Adaptive Systems Based Data Integration : Theory And Applications, Eliahu Rohn

Dissertations

Data Definition Languages (DDLs) have been created and used to represent data in programming languages and in database dictionaries. This representation includes descriptions in the form of data fields and relations in the form of a hierarchy, with the common exception of relational databases where relations are flat. Network computing created an environment that enables relatively easy and inexpensive exchange of data. What followed was the creation of new DDLs claiming better support for automatic data integration. It is uncertain from the literature if any real progress has been made toward achieving an ideal state or limit condition of automatic ...


Some Combinational Optimization Problems On Radio Network Communication And Machine Scheduling, Xin Wang Dec 2007

Some Combinational Optimization Problems On Radio Network Communication And Machine Scheduling, Xin Wang

Dissertations

The combinatorial optimization problems coming from two areas are studied in this dissertation: network communication and machine scheduling.

In the network communication area, the complexity of distributed broadcasting and distributed gossiping is studied in the setting of random networks. Two different models are considered: one is random geometric networks, the main model used to study properties of sensor and ad-hoc networks, where ri points are randomly placed in a unit square and two points are connected by an edge if they are at most a certain fixed distance r from each other. The other model is the so-called line-of-sight networks ...


Abstraction, Extension And Structural Auditing With The Umls Semantic Network, Yan Chen Dec 2007

Abstraction, Extension And Structural Auditing With The Umls Semantic Network, Yan Chen

Dissertations

The Unified Medical Language System (UMLS) is a two-level biomedical terminological knowledge base, consisting of the Metathesaurus (META) and the Semantic Network (SN), which is an upper-level ontology of broad categories called semantic types (STs). The two levels are related via assignments of one or more STs to each concept of the META.

Although the SN provides a high-level abstraction for the META, it is not compact enough. Various metaschemas, which are compact higher-level abstraction networks of the SN, have been derived. A methodology is presented to evaluate and compare two given metaschemas, based on their structural properties. A consolidation ...


Exploiting Self-Assembly For Ligand-Scaffold Optimization: Substrate-Tailored Ligands For Efficient Catalytic Asymmetric Hydroboration, Shin A. Moteki, James M. Takacs Dec 2007

Exploiting Self-Assembly For Ligand-Scaffold Optimization: Substrate-Tailored Ligands For Efficient Catalytic Asymmetric Hydroboration, Shin A. Moteki, James M. Takacs

James Takacs Publications

A self-assembled ligand library (SAL XY) affords a wide range of R/S ratios in Rh-catalyzed asymmetric hydroboration (nbd = 2,5norbornadiene, R* is a chiral substituent). Ligand-scaffold optimization reveals “substrate-tailored” ligands that afford high regio- and enantioselectivity for a variety of ortho-substituted styrene derivatives.

Includes article (4 pp.) and supporting information (106 pp.).


Flux, Gaugino Condensation, And Antibranes In Heteroic M Theory, James Gray, André Lukas, Burt A. Ovrut Dec 2007

Flux, Gaugino Condensation, And Antibranes In Heteroic M Theory, James Gray, André Lukas, Burt A. Ovrut

Department of Physics Papers

We present the potential energy due to flux and gaugino condensation in heterotic M theory compactifications with antibranes in the vacuum. For reasons which we explain in detail, the contributions to the potential due to flux are not modified from those in supersymmetric contexts. The discussion of gaugino condensation is, however, changed by the presence of antibranes. We show how a careful microscopic analysis of the system allows us to use standard results in supersymmetric gauge theory in describing such effects—despite the explicit supersymmetry breaking which is present. Not surprisingly, the significant effect of antibranes on the threshold corrections ...


Science Plan For Potential 2008 Experimental High Flow At Glen Canyon Dam, Grand Canyon Monitoring And Research Center Dec 2007

Science Plan For Potential 2008 Experimental High Flow At Glen Canyon Dam, Grand Canyon Monitoring And Research Center

All U.S. Government Documents (Utah Regional Depository)

No abstract provided.


Taux : A System For Evaluating Sound Feedback In Navigational Tasks, Robert J. Lutz Dec 2007

Taux : A System For Evaluating Sound Feedback In Navigational Tasks, Robert J. Lutz

Dissertations

This thesis presents the design and development of an evaluation system for generating audio displays that provide feedback to persons performing navigation tasks. It first develops the need for such a system by describing existing wayfinding solutions, investigating new electronic location-based methods that have the potential of changing these solutions and examining research conducted on relevant audio information representation techniques. An evaluation system that supports the manipulation of two basic classes of audio display is then described. Based on prior work on wayfinding with audio display, research questions are developed that investigate the viability of different audio displays. These are ...