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Beyond Functional Diversity: The Importance Of Trophic Position To Understanding Functional Processes In Community Evolution, Roxanne M. W. Banker, Ashley A. Dineen, Melanie G. Sorman, Carrie L. Tyler, Peter D. Roopnarine

Geoscience Faculty Research

Ecosystem structure—that is the species present, the functions they represent, and how those functions interact—is an important determinant of community stability. This in turn a􀀀ects how ecosystems respond to natural and anthropogenic crises, and whether species or the ecological functions that they represent are able to persist. Here we use fossil data from museum collections, literature, and the Paleobiology Database to reconstruct trophic networks of Tethyan paleocommunities fromthe Anisian and Carnian (Triassic), Bathonian (Jurassic), and Aptian (Cretaceous) stages, and compare these to a previously reconstructed trophic network from a modern Jamaican reef community. We generated model food webs consistent with …

Long Range Correlation Of Molecular Orientation And Vibration In Liquid Cdcl3, David P. Shelton

Physics & Astronomy Faculty Research

The polarization dependence of hyper-Rayleigh second harmonic light scattering (SHS) and hyper-Raman light scattering (HRS) measured for liquid CDCl₃ show the effect of long-range correlation of molecular orientation and vibration. HRS from the ν₁, ν₄, and ν₅ vibration modes is polarized transverse to the scattering wavevector, whereas HRS from the ν₂, ν₃, and ν₆ vibration modes and SHS from the ν₀ orientation mode all show longitudinal polarization. The transverse polarized HRS is accounted for by long range vibration correlation due to dipole–dipole interaction for molecules at 20–400 nm …

Groundwater Quality: Global Challenges, Emerging Threats And Novel Approaches, Dan Lapworth, Thomas Boving, Bentje Brauns, Jane Dottridge, Paul Hynds, Seifu Kebede, David Kreamer, Bruce Misstear, Abhijit Mukherjee, Viviana Re, James Sorensen, Claudia Ruz Vargas

Geoscience Faculty Research

Improving our understanding of groundwater quality threats to human health and the environment is essential to protect and manage groundwater resources effectively. This essay highlights some global groundwater quality challenges, describes key contaminant groups and threats of emerging concern, including antimicrobial resistance, and discusses novel approaches to assessing groundwater quality. Groundwater quality monitoring needs to improve significantly in order to effectively identify and mitigate threats to groundwater from historical, current and future pollution.

Eclipse Of The V773 Tau B Circumbinary Disc, M. A. Kenworthy, D. González Picos, E. Elizondo, R. G. Martin, D. M. Van Dam, J. E. Rodriguez, G. M. Kennedy, C. Ginski, M. Mugrauer, N. Vogt, C. Adam, R. J. Oelkers

Physics & Astronomy Faculty Research

Context. Young multiple stellar systems can host both circumstellar and circumbinary discs composed of gas and dust, and the orientations of circumbinary discs can be sculpted by the orientation and eccentricity of the central binaries. Studying multiple binary systems and their associated discs enables our understanding of the size and distribution of the planetary systems that subsequently form around them.

Aims. A deep (~70%) and extended (~150 days) eclipse was seen towards the young multiple stellar system V773 Tau in 2010. We interpret it as being due to the passage of a circumbinary disc around the B components moving in …

Nemesis Setup For Indirect Detection Of Wimps, W. H. Trzaska, Alexander Barzilov, T. Enqvist, K. Jedrzejczak, J. Joutsenvaara, M. Kasztelan, O. Kotavaara, P. Kuusiniemi, K. K. Loo, J. Orzechowski, J. Puputti, M. Slupecki, J. Szabelski, I. Usoskin, T. E. Ward

Mechanical Engineering Faculty Research

We summarize the evidence for DM-like anomalies in neutron multiplicity spectra collected underground with Pb targets by three independent experiments: NEMESIS (at 210 m.w.e.) NMDS (at 583 m.w.e.), and ZEPLIN-II (at 2850 m.w.e.). A new analysis shows small but persistent anomalies at high neutron multiplicities. Adjusted for differences in detection efficiencies, the positions of the anomalies are consistent between the three systems. Also, the intensities match when corrected for the acquisition time and estimated detection efficiency. While the three measurements are inconclusive when analyzed separately, together, they exclude a statistical fluke to better than one in a million. To prove …

Saturable Absorption Of Free-Electron Laser Radiation By Graphite Near The Carbon K-Edge, Lars Hoffman, Sasawat Jamnuch, Craig Schwartz, Tobias Helk, Sumana L. Raj, Hikaru Mizuno, Riccardo Mincigrucci, Laura Foglia, Emiliano Principi, Richard J. Saykally, Walkter S. Drisdell

Nevada Extreme Conditions Laboratory Faculty Research

The interaction of intense light with matter gives rise to competing nonlinear responses that can dynamically change material properties. Prominent examples are saturable absorption (SA) and two-photon absorption (TPA), which dynamically increase and decrease the transmission of a sample depending on pulse intensity, respectively. The availability of intense soft X-ray pulses from free-electron lasers (FELs) has led to observations of SA and TPA in separate experiments, leaving open questions about the possible interplay between and relative strength of the two phenomena. Here, we systematically study both phenomena in one experiment by exposing graphite films to soft X-ray FEL pulses of …

A Wind Environment And Lorentz Factors Of Tens Explain Gamma-Ray Bursts X-Ray Plateau, Hüsne Dereli-Bégué, Asaf Pe’Er, Felix Ryde, Samantha R. Oates, Bing Zhang, Maria G. Dainotti

Physics & Astronomy Faculty Research

Gamma-ray bursts (GRBs) are known to have the most relativistic jets, with initial Lorentz factors in the order of a few hundreds. Many GRBs display an early X-ray light-curve plateau, which was not theoretically expected and therefore puzzled the community for many years. Here, we show that this observed signal is naturally obtained within the classical GRB fireball model, provided that the initial Lorentz factor is rather a few tens, and the expansion occurs into a medium-low density wind. The range of Lorentz factors in GRB jets is thus much wider than previously thought and bridges an observational gap between …

Distributions Of Gas And Small And Large Grains In The Lkh 330 Disk Trace A Young Planetary System, Paola Pinilla, Myriam Benisty, Nicolás T. Kurtovic, Jaehan Bae, Ruobing Dong, Zhaohuan Zhu, S. Andrews, J. Carpenter, C. Ginski, J. Huang, A. Isella, L. Perez, L. Ricci, G. Rosotti, M. Villenave, D. Wilner

Physics & Astronomy Faculty Research

Planets that are forming around young stars are expected to leave clear imprints in the distribution of the gas and dust of their parental protoplanetary disks. In this paper, we present new scattered light and millimeter observations of the protoplanetary disk around LkH 330, using SPHERE/VLT and ALMA, respectively. The scattered-light SPHERE observations reveal an asymmetric ring at around 45au from the star in addition to two spiral arms with similar radial launching points at around 90au. The millimeter observations from ALMA (resolution of 006 004 ) mainly show an asymmetric ring located at 110au from the star. In addition …

Improving The Conductivity Of Graphite-Based Films By Rapid Laser Annealing, Gulsum Ersu, Sruthi Kuriakose, Stuart J. Goldie, Abdullah M. Al-Enizi, Ayman Nafady, Carmen Munuera, Claudia Backes, Joshua O. Island, Andres Castellanos-Gomez

Physics & Astronomy Faculty Research

We present a method to anneal devices based on graphite films on paper and polycarbonate substrates. The devices are created using four different methods: spray-on films, graphite pencil-drawn films, liquid-phase exfoliated graphite films, and graphite powder abrasion-applied films. We characterize the optical properties of the films before and after laser annealing and report the two-terminal resistance of the devices for increased laser power density. We find the greatest improvement (16× reduction) in the resistance of spray-on film devices starting from 25.0 kΩ and reaching 1.6 kΩ at the highest annealing power densities. These improvements are attributed to local laser ablation …

Science And Engineering State Indicators: Mountain West States, Olivia K. Cheche, Kristian Thymianos, Caitlin J. Saladino, William E. Brown Jr.

Higher Education

This fact sheet examines the Science & Engineering State Indicators database from the National Science Foundation (NSF) for the Mountain West states of Arizona, Colorado, Nevada, New Mexico, and Utah.

Aapm Wgpdmp Report 373: The Content, Structure, And Value Of The Professional Doctorate In Medical Physics (Dmp), Jay W. Burmeister, Charles W. Coffey, John D. Hazle, Neil Kirby, Yu Kuang, Michael A. Lamba, Brian Loughery, Niko Papanikolaou

Integrated Health Sciences Faculty Research

The Professional Doctorate in Medical Physics (DMP) was originally conceived as a solution to the shortage of medical physics residency training positions. While this shortage has now been largely satisfied through conventional residency training positions, the DMP has expanded to multiple institutions and grown into an educational pathway that provides specialized clinical training and extends well beyond the creation of additional training spots. As such, it is important to reevaluate the purpose and the value of the DMP. Additionally, it is important to outline the defining characteristics of the DMP to assure that all existing and future programs provide this …

Combining Freestanding Ferroelectric Perovskite Oxides With Two-Dimensional Semiconductors For High Performance Transistors, Sergio Puebla, Thomas Pucher, Victor Rouco, Gabriel Sanchez-Santolino, Yong Xie, Victor Zamora, Fabian A. Cuellar, Federico J. Mompean, Carlos Leon, Carlos O. Island, Mar Garcia-Hernandez, Jacobo Santamaria, Carmen Munuera, Andres Castellanos-Gomez

Physics & Astronomy Faculty Research

We demonstrate the fabrication of field-effect transistors based on single-layer MoS2 and a thin layer of BaTiO3 (BTO) dielectric, isolated from its parent epitaxial template substrate. Thin BTO provides an ultrahigh-κ gate dielectric effectively screening Coulomb scattering centers. These devices show mobilities substantially larger than those obtained with standard SiO2 dielectrics and comparable with values obtained with hexagonal boron nitride, a dielectric employed for fabrication of high-performance two-dimensional (2D) based devices. Moreover, the ferroelectric character of BTO induces a robust hysteresis of the current vs gate voltage characteristics, attributed to its polarization switching. This hysteresis is strongly suppressed when the …

Ambient-Pressure Ozone Treatment Enables Tuning Of Oxygen Vacancy Concentration In The La1−XSrXFeo3−Δ (0 ≤ X ≤ 1) Perovskite Oxides, Geletu Qing, David Thompson, Mourad Benamara, Clemens Heske, Lauren Greenlee, Jingyi Chen

Chemistry and Biochemistry Faculty Research

Oxygen vacancies in metal oxides can determine their properties. However, it is difficult to reduce the oxygen vacancy concentration in metal oxides without annealing them under high pressure. In this work, we develop a facile approach to control oxygen vacancy content via an ozone treatment under ambient pressure during cooling. This approach is demonstrated for the synthesis of La_1−xSr_xFeO_3−δ (0 ≤ x ≤ 1, 0 ≤ δ ≤ 0.5x) perovskite oxides – an important class of energy-related materials due to their wide range of non-stoichiometry, mixed ionic and electronic conductivity, and …

A Design Framework Of Exploration, Segmentation, Navigation, And Instruction (Esni) For The Lifecycle Of Intelligent Mobile Agents As A Method For Mapping An Unknown Built Environment, Junchi Chu, Xueyun Tang, Xiwei Shen

Architecture Faculty Research

Recent work on intelligent agents is a popular topic among the artificial intelligence community and robotic system design. The complexity of designing a framework as a guide for intelligent agents in an unknown built environment suggests a pressing need for the development of autonomous agents. However, most of the existing intelligent mobile agent design focus on the achievement of agent’s specific practicality and ignore the systematic integration. Furthermore, there are only few studies focus on how the agent can utilize the information collected in unknown build environment to produce a learning pipeline for fundamental task prototype. The hierarchical framework is …

Understanding Inservice Middle School Teachers’ Views Of Nature Of Science (Vnos), Merika Charupoom, Yasmeen Hernandez, Emily Carter, Nicole J. Thomas, Tina Vo

Spectra Undergraduate Research Journal

The Nature of Science (NOS) is a component of science literacy that supports critical thinking around science concepts, speaking to how and why science is conducted and connected to creating data and evidence. NOS is designed to be more than the standardized lessons of science; it helps children critically analyze and solve real-world and societal issues using scientific knowledge. The interpretation of science varies between the ideology and beliefs of each individual. Given the importance of this idea, it is necessary that teachers be able to provide NOS opportunities to students; however, first, they must have a firm grasp of …

How Facial Features Convey Attention In Stationary Environments, Janelle Domantay, Brendan Morris

Spectra Undergraduate Research Journal

Awareness detection technologies have been gaining traction in a variety of enterprises; most often used for driver fatigue detection, recent research has shifted towards using computer vision technologies to analyze user attention in environments such as online classrooms. This paper aims to extend previous research on distraction detection by analyzing which visual features contribute most to predicting awareness and fatigue. We utilized the open-source facial analysis toolkit OpenFace in order to analyze visual data of subjects at varying levels of attentiveness. Then, using a Support-Vector Machine (SVM) we created several prediction models for user attention and identified the Histogram of …

Acreage Of Foreign Owned Farmland In The Mountain West, 2020, Geneva Martin, Saha Salahi, Zachary Billot, Caitlin J. Saladino, William E. Brown Jr.

Housing & Real Estate

This fact sheet examines foreign-owned farmland in the Mountain West states of Arizona, Colorado, Nevada, New Mexico, and Utah, as originally reported by the United States Department of Agriculture’s (USDA) Farm Service Agency.

Compositionally And Density Stratified Igneous Terrain In Jezero Crater, Mars, Roger C. Wiens, Arya Udry, Olivier Beyssac, Cathy Quantin-Nataf, Nicolas Mangold, 80+ Authors Contributed To This Work

Geoscience Faculty Research

Before Perseverance, Jezero crater’s floor was variably hypothesized to have a lacustrine, lava, volcanic airfall, or aeolian origin. SuperCam observations in the first 286 Mars days on Mars revealed a volcanic and intrusive terrain with compositional and density stratification. The dominant lithology along the traverse is basaltic, with plagioclase enrichment in stratigraphically higher locations. Stratigraphically lower, layered rocks are richer in normative pyroxene. The lowest observed unit has the highest inferred density and is olivine-rich with coarse (1.5 millimeters) euhedral, relatively unweathered grains, suggesting a cumulate origin. This is the first martian cumulate and shows similarities to martian meteorites, which …

An Automated System For Strain Engineering And Straintronics Of 2d Materials, Onur Çakıroğlu, Joshua O. Island, Yong Xie, Riccardo Frisenda, Andres Castellanos-Gomez

Physics & Astronomy Faculty Research

This work presents an automated three-point bending apparatus that can be used to study strain engineering and straintronics in 2D materials. This work benchmarks the system by reporting reproducible strain tuned micro-reflectance, Raman, and photoluminescence spectra for monolayer molybdenum disulfide (MoS2). These results are in good agreement with reported literature using conventional bending apparatus. This work further utilizes the system to automate strain investigations of straintronic devices by measuring the piezoresistive effect and the strain effect on photoresponse in an MoS2 electrical device. The details of the construction of the straightforward system are given and it is anticipated that it …

Knowing When To Fold'em: A Monte Carlo Exploration Of Card Shuffling And How Poker Players Can Gain An Advantage, David W. Merz, Peter B. Chi

UNLV Gaming Research & Review Journal

This work demonstrates that the card shuffling procedure commonly performed in casino poker rooms is insufficient for randomizing a deck of cards. We explore this in the context of Texas Hold’em, which has established itself as the most popular form of poker worldwide over the past few decades. We show the degree to which the resulting distribution of the orderings of all 52 cards in the deck after shuffling is not uniform. Rather, any given card may be substantially more (or less) likely to show up as an important card in the subsequent hand. Additionally, we find that the shuffling …

Low-Cost And Biodegradable Thermoelectric Devices Based On Van Der Waals Semiconductors On Paper Substrates, Gulsum Ersu, Carmen Munuera, Federico J. Mompean, Daniel Vaquero, Jorge Quereda, Jooao Elias Rodrigues, Jose A. Alonso, Eduardo Flores, Jose R. Ares, Isbael J. Ferrer, Adbullah M. Al-Enizi, Ayman Nafady, Sruthi Kuriakose, Joshua O. Island, Andres Castellanos-Gomez

Physics & Astronomy Faculty Research

We present a method to fabricate handcrafted thermoelectric devices on standard office paper substrates. The devices are based on thin films of WS2, Te, and BP (P-type semiconductors) and TiS3 and TiS2 (N-type semiconductors), deposited by simply rubbing powder of these materials against paper. The thermoelectric properties of these semiconducting films revealed maximum Seebeck coefficients of (+1.32 ± 0.27) mV K−1 and (−0.82 ± 0.15) mV K−1 for WS2 and TiS3, respectively. Additionally, Peltier elements were fabricated by interconnecting the P- and N-type films with graphite electrodes. A thermopower value up to 6.11 mV K−1 was obtained when the Peltier …

Renewable Energy Legislation In Nevada: 2017 - 2021, Peter Grema, Zachary Walusek, Caitlin J. Saladino, William E. Brown Jr.

Environment

The purpose of this fact sheet is to summarize legislative actions from the biennial 79th, 80th, and 81st Nevada Legislative Sessions (2017, 2019, and 2021) regarding solar energy production and state efforts to reach 50 percent energy production from renewable sources by 2030. By 2050, Nevada has a statutorily mandated obligation to be a net-zero carbon producer in fulfilling energy production needs from large scale utility services.

Artificial Intelligence In The Radiomic Analysis Of Glioblastomas: A Review, Taxonomy, And Perspective, Ming Zhu, Sijia Li, Yu Kuang, Virginia B. Hill, Amy B. Heimberger, Lijie Zhai, Shenjie Zhai

Electrical & Computer Engineering Faculty Research

Radiological imaging techniques, including magnetic resonance imaging (MRI) and positron emission tomography (PET), are the standard-of-care non-invasive diagnostic approaches widely applied in neuro-oncology. Unfortunately, accurate interpretation of radiological imaging data is constantly challenged by the indistinguishable radiological image features shared by different pathological changes associated with tumor progression and/or various therapeutic interventions. In recent years, machine learning (ML)-based artificial intelligence (AI) technology has been widely applied in medical image processing and bioinformatics due to its advantages in implicit image feature extraction and integrative data analysis. Despite its recent rapid development, ML technology still faces many hurdles for its broader applications …

Monte Carlo Simulation Of Thallium-Bromide Semiconductor Detector For Range Verification Of A Carbon Ion Radiotherapy Beam Through Prompt Gamma-Ray Detection, Peter Dimpfl

UNLV Theses, Dissertations, Professional Papers, and Capstones

Thallium-Bromide is a semiconductor material which is well suited for photon detection. Composed of high atomic number elements and a high mass density of 7.56 g/cm3, TlBr has superb photon stopping power. External beam radiation therapy is an ever-changing environment with technology rapidly improving. With proton therapy facilities becoming more widely available, and carbon ion facilities showcasing the benefits of carbon ion radiation therapy, there is an industry need toprovide accurate dosimetric treatment plans to verify patients are receiving proper care. Current clinical practices apply safety margins to clinical target volumes to safe treatment. Through research to improve detection techniques, …

Effect Of Metronome, Hospital Mattress, And Step Stool Usage On Chest Compression Rate And Depth During Cardiopulmonary Resuscitation (Cpr): A Collection Of Systematic Reviews And Meta-Analyses, Lee A. Doernte

UNLV Theses, Dissertations, Professional Papers, and Capstones

We conducted a systematic review and meta-analysis to evaluate the effects of: (1) a metronome, (2) a hospital mattress, and (3) a step stool on chest compression rate and chest compression depth during cardiopulmonary resuscitation (CPR). These studies comply with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist for searches and reporting systematic reviews. We utilized the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) to categorize the certainty of evidence.The first analysis focused on metronome usage while performing CPR. Our methods for this study were to conduct literature searches for studies comparing metronome usage to a …

Antler Foreland Basin Evolution Recorded In Detrital Zircon U-Pb Geochronology, James Duncan

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Antler orogeny was a Devonian-Mississippian (375-320 Ma) mountain building event that occurred along the western Laurentian margin. The initiation of the Antler orogeny is marked by the emplacement of the Roberts Mountain Allochthon (RMA) that thrust Cambrian-Devonian deep water marine siliciclastic rocks 100 km eastward onto the western Laurentian margin. Shortening related to the Antler orogeny deformed RMA strata and caused a flexural response in the continental crust that resulted in the formation of the adjacent Antler Foreland basin. The paleogeographic history of the RMA strata and tectonic drivers for the Antler orogeny are still debated. Proposed models suggest …

Dissolution And Electrochemical Recovery Of Uo2, Uo3, And U3o8 In Ionic Liquids, Katherine Iolani Thornock Luebke

UNLV Theses, Dissertations, Professional Papers, and Capstones

This research explores a novel method of increasing the solubility of uranium oxides and other actinide oxides in room temperature ionic liquids (IL) using direct dissolution. The goal is to further expand our knowledge of actinide dissolution and possible nuclear fuel cycle material applications using ionic liquids. The novelty of the methods is focused on the use of oxidizing gas generated using air passed through an ozone generator. While examples of dissolution exist in IL using acidic functionalized ionic liquids, the solubility of all possible oxide species was not demonstrated. Also, the addition of aqueous acid to IL containing actinide …

Hyperspectral Image Analysis Of Food For Nutritional Intake, Shirin Nasr Esfahani

UNLV Theses, Dissertations, Professional Papers, and Capstones

The primary object of this dissertation is to investigate the application of hyperspectral technology to accommodate for the growing demand in the automatic dietary assessment applications. Food intake is one of the main factors that contribute to human health. In other words, it is necessary to get information about the amount of nutrition and vitamins that a human body requires through a daily diet. Manual dietary assessments are time-consuming and are also not precise enough, especially when the information is used for the care and treatment of hospitalized patients. Moreover, the data must be analyzed by nutritional experts. Therefore, researchers …

Source And Parental Melts Of Poikilitic Shergottites: Implications For Martian Magmatism, Evan W. O'Neal

UNLV Theses, Dissertations, Professional Papers, and Capstones

Martian poikilitic shergottite meteorites are cumulate rocks that can be used to understand melt evolution on Mars from the bottom of the crust (~10 kbar) all the way up to near-surface shallow depths (~1 kbar). There is a general lack of knowledge regarding shergottites including, parental magma compositions, crystallization ages, and the location of the enriched geochemical source of the shergottites in the martian mantle. Through a comprehensive petrographic and geochemical study, we have attempted to better understand poikilitic shergottite formation and the evolution of the martian interior during the Amazonian period (~3 Ga – present day). We studied a …

The Application Of Detrital Zircon Geochronology, Pressure-Temperature Modeling, Monazite Petrochronology, And Quartz-In-Garnet Elastic Geobarometry To The Tectonic Evolution Of The Funeral Mountains And Related Metamorphic Core Complexes, Suzanne Renae Mulligan

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation investigates and applies different techniques for studying mid-crustal metamorphic rocks including detrital zircon geochronology, monazite petrochronology, thermodynamic pressure-temperature modeling, and elastic geobarometry. The first chapter reconstructs stratigraphy in deformed metamorphic rocks from the Funeral Mountains metamorphic core complex in Death Valley, California, and the Bullfrog Hills, Nevada, using U-Pb detrital zircon (DZ) geochronology. This study documents another successful application of stratigraphic techniques applied to metamorphic rocks and migmatites. DZ geochronology identified Pahrump Group metasediments in rocks that were previously interpreted to be Paleoproterozoic basement gneisses, providing insights into the distribution of Rodinia rift basins. This analysis has shown …