Physical Sciences and Mathematics Commons^™

Acrb Trimer Stability And Efflux Activity, Insight From Mutagenesis Studies, Linliang Yu, Wei Lu, Yinan Wei

Chemistry Faculty Publications

The multidrug transporter AcrB in Escherichia coli exists and functions as a homo-trimer. The assembly process of obligate membrane protein oligomers, including AcrB, remains poorly understood. In a previous study, we have shown that individual AcrB subunit is capable of folding independently, suggesting that trimerization of AcrB follows a three-stage pathway in which monomers first fold, and then assemble. Here we destabilized the AcrB trimer through mutating a single Pro (P223) in the protruding loop of AcrB, which drastically reduced the protein activity. We replaced P223 separately with five residues, including Ala, Val, Tyr, Asn, and Gly, and found that …

Nanozeolites Doped Photopolymer Layers With Reduced Shrinkage, Mohesh Moothanchery, Izabela Naydenova, Svetlana Mintova, Vincent Toal

Articles

An acrylamide based photopolymer doped with pure silica MFI-type zeolite (silicalite-1) nanoparticles has been characterized for holographic recording purposes. The concentrations of the silicalite-1 nanoparticles in the photopolymer layers were 1, 2.5, 5 and 7.5 wt.%. The inclusion of silicalite-1 nanoparticle in the photopolymer has resulted in an increase of the diffraction efficiency by up to 40%, and decrease of the shrinkage from 1.32% to 0.57%. The best results were obtained in layers doped with 5 wt.% silicalite-1 nanoparticles.

The Laboca Survey Of The Extended Chandra Deep Field-South: Clustering Of Submillimetre Galaxies, Ryan C. Hickox, J. L. Wardlow, Ian Smail, A. D. Myers

Dartmouth Scholarship

We present a measurement of the spatial clustering of submillimetre galaxies (SMGs) at z = 1–3. Using data from the 870 μm LABOCA submillimetre survey of the Extended Chandra Deep Field South, we employ a novel technique to measure the cross-correlation between SMGs and galaxies, accounting for the full probability distributions for photometric redshifts of the galaxies. From the observed projected two-point cross-correlation function we derive the linear bias and characteristic dark matter halo masses for the SMGs. We detect clustering in the cross-correlation between SMGs and galaxies at the > 4σ level. Accounting for the clustering of galaxies from their …

Analyzing Ecohydrology Of Subirrigated Meadow, Dry Valley And Upland Dune Ecosystems Using Remote Sensing And In-Situ Estimations In The Semiarid Sand Hills Region Of Nebraska, Usa, Nathan C. Healey

School of Natural Resources: Dissertations, Theses, and Student Research

Nebraska’s dependence upon the High Plains (Ogallala) Aquifer for agricultural production is vital to the state’s economy, ecology and hydrology. The Sand Hills region (58,000 km²) of Nebraska is a unique system of lakes, (~5%) wetlands, (~10%) subirrigated meadows, (~20%) dry valleys and (~65%) upland sand dune ecosystems. Understanding how each of these land cover types reacts to climate conditions of different water limitations is vital to regional water resource management. This research explores the ecohydrological behavior of different land cover types at the Gudmundsen Sand Hills Research Laboratory (GSRL) near Whitman, Nebraska in the heart of the …

Remote Analysis Of Grain Size Characteristic In Submarine Pyroclastic Deposits From Kolumbo Volcano, Greece, Clara Smart, D. P. Whitesell, Christopher N. Roman, Steven Carey

Graduate School of Oceanography Faculty Publications

Grain size characteristics of pyroclastic deposits provide valuable information about source eruption energetics and depositional processes. Maximum size and sorting are often used to discriminate between fallout and sediment gravity flow processes during explosive eruptions. In the submarine environment the collection of such data in thick pyroclastic sequences is extremely challenging and potentially time consuming. A method has been developed to extract grain size information from stereo images collected by a remotely operated vehicle (ROV). In the summer of 2010 the ROV Hercules collected a suite of stereo images from a thick pumice sequence in the caldera walls of Kolumbo …

Detection Of Diffuse Sea Floor Venting Using Structured Light Imaging, Gabrielle Inglis, Clara Smart, Christopher Roman, Steven Carey

Graduate School of Oceanography Faculty Publications

Efficiently identifying and localizing diffuse sea floor venting at hydrothermal and cold seep sites is often difficult. Actively venting fluids are usually identified by a temperature induced optical shimmering seen during direct visual inspections or in video data collected by vehicles working close to the sea floor. Relying on such direct methods complicates establishing spatial relations between areas within a survey covering a broad area. Our recent work with a structured light laser system has shown that venting can also be detected in the image data in an automated fashion. A structured light laser system consists of a camera and …

User Choice Between Traditional And Computerized Methods: An Activity Perspective, Jun Sun

Information Systems Faculty Publications and Presentations

Numerous computerized methods emerge to replace traditional methods in people’s personal, work and social lives, but many are hesitant to make the transition. This study examines the factors that influence human choice between different methods. According to Activity Theory, traditional and computerized methods are both tools that a person uses for a certain task. The situated experiences with various methods shape people’s attitude toward using them later in terms of tool readiness. The understanding leads to hypothesized relationships between user-, method- and task-specific factors and the dependent variable. The results from an empirical study support that method experiences have strong …

Inferring Phytoplankton Carbon And Eco-Physiological Rates From Diel Cycles Of Spectral Particulate Beam-Attenuation Coefficient, G. Dall'olmo, E. Boss, M. J. Behrenfeld, T. K. Westberry, C. Courties, L. Prieur, M. Pujo-Pay, N. Hardman-Mountford, T. Moutin

Marine Sciences Faculty Scholarship

The diurnal fluctuations in solar irradiance impose a fundamental frequency on ocean biogeochemistry. Observations of the ocean carbon cycle at these frequencies are rare, but could be considerably expanded by measuring and interpreting the inherent optical properties. A method is presented to analyze diel cycles in particulate beam-attenuation coefficient (cp) measured at multiple wavelengths. The method is based on fitting observations with a size-structured population model coupled to an optical model to infer the particle size distribution and physiologically relevant parameters of the cells responsible for the measured diel cycle in cp. Results show that the information related to size …

A Search For The Transit Of Hd 168443b: Improved Orbital Parameters And Photometry, Genady Pilyavsky, Suvrath Mahadevan, Stephen R. Kane, Andrew W. Howard, David R. Ciardi, Chris De Pree, Diana Dragomir, Debra A. Fischer, Gregory W. Henry, Eric L. N. Jensen, Gregory Laughlin

Information Systems and Engineering Management Research Publications

The discovery of transiting planets around bright stars holds the potential to greatly enhance our understanding of planetary atmospheres. In this work we present the search for transits of HD 168443b, a massive planet orbiting the bright star HD 168443 (V = 6.92) with a period of 58.11 days. The high eccentricity of the planetary orbit (e = 0.53) significantly enhances the a priori transit probability beyond that expected for a circular orbit, making HD 168443 a candidate for our ongoing Transit Ephemeris Refinement and Monitoring Survey. Using additional radial velocities from Keck High Resolution Echelle Spectrometer, we refined the …

Global Change, Global Trade, And The Next Wave Of Plant Invasions, Bethany A. Bradley, Dana M. Blumenthal, Regan Early, Edwin D. Grosholz, Joshua J. Lawler, Luke P. Miller, Cascade J.B. Sorte, Carla M. D'Antonio, Jeffrey M. Diez, Jeffrey S. Dukes, Ines Ibanez, Julian D. Olden

Faculty Publications, Biological Sciences

Many non-native plants in the US have become problematic invaders of native and managed ecosystems, but a new generation of invasive species may be at our doorstep. Here, we review trends in the horticultural trade and invasion patterns of previously introduced species and show that novel species introductions from emerging horticultural trade partners are likely to rapidly increase invasion risk. At the same time, climate change and water restrictions are increasing demand for new types of species adapted to warm and dry environments. This confluence of forces could expose the US to a range of new invasive species, including many …

A Study Of Correlations Between The Definition And Application Of The Gene Ontology, Yuji Mo

Computer and Electronics Engineering: Dissertations, Theses, and Student Research

When using the Gene Ontology (GO), nucleotide and amino acid sequences are annotated by terms in a structured and controlled vocabulary organized into relational graphs. The usage of the vocabulary (GO terms) in the annotation of these sequences may diverge from the relations defined in the ontology. We measure the consistency of the use of GO terms by comparing GO's defined structure to the terms' application. To do this, we first use synthetic data with different characteristics to understand how these characteristics influence the correlation values determined by various similarity measures. Using these results as a baseline, we found that …

Development And Optimization Of Organic Based Monoliths For Use In Affinity Chromatography, Erika L. Pfaunmiller

Department of Chemistry: Dissertations, Theses, and Student Research

Affinity chromatography is an important and useful tool for studying biological interactions, such as the binding of an antibody with an antigen. Monolithic supports offer many advantages over traditional packed bed supports in affinity chromatography, including their ease of preparation, low back pressures and good mass transfer properties. Monoliths can be broken down into two basic categories: organic (polymer) and inorganic (silica) monoliths. There are many varieties of polymer based monoliths; however, a large focus has been on co-polymers of glycidyl methacrylate (a functional monomer) and ethylene dimethacrylate (a cross-linking agent). The solvents of choice for making this type of …

Two Dimensional Electron Gas At Oxide Interfaces, Karolina Janicka

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

Extraordinary phenomena can occur at the interface between two oxide materials. A spectacular example is a formation of a two-dimensional electron gas (2DEG) at the SrTiO₃/LaAlO₃ interface. In this dissertation the properties of the 2DEG are investigated from first principles.

The spatial extent of the 2DEG formed at the SrTiO₃/LaAlO₃ n-type interface is studied. It is shown that the confinement of the 2DEG is controlled by metal induced gap states formed in the band gap of SrTiO₃. The confinement width is then determined by the attenuation length of the metal induced gap …

Studying The Handling Of Heat Stressed Cattle Using The Additive Bi-Logistic Model To Fit Body Temperature, Fan Yang

Department of Statistics: Dissertations, Theses, and Student Work

Daily activities consume the energy of heifers, subsequently causing an elevation of body temperature, depending on the ambient conditions. A better understanding of the dynamics of body temperature (Tb) would be helpful when deciding how to process and handle heifers. It would also lead to specific recommendations on moving heifers under different ambient conditions, especially during the summer. In this study, a bi-logistic mixed model is used to describe the dynamics of Tb during the moving event. Data were taken from heifers in pens located at different distances from the heifer work station on four separate summer days under hot …

Ecophysiological Responses Of Herbaceous Plants To The Presence Or Absence Of Amorpha Canescens In A Nebraska Sandhills Grassland, Jessica L. Milby

School of Natural Resources: Dissertations, Theses, and Student Research

Deeply-rooted shrubs are a common component of grasslands. This study investigated the ecophysiological role of Amorpha canescens, a common leguminous shrub, in Sandhills grassland, and response of herbaceous plants to the presence or absence of A. canescens. Two sites were selected for the study at the Gudmundsen Sandhills Laboratory near Whitman, Nebraska – one with A. canescens (G-L) and one without (G-NL) A. canescens. Plant canopy cover and aboveground biomass were characterized on both sites in June and August 2010. Seasonal trends in net photosynthesis (A), stomatal conductance (gs), transpiration (E), water use efficiency (WUE), and predawn …

Climatic Controls On The Summertime Energy Balance Of A Thermokarst Lake In Northern Alaska: Short-Term, Seasonal, And Interannual Variability, Brittany L. Potter

School of Natural Resources: Dissertations, Theses, and Student Research

Shallow, thermokarst lakes that develop atop permafrost are a prominent landscape feature on the Arctic Coastal Plain (ACP) of northern Alaska. The ACP is vulnerable to ongoing climate change and landscape modification, as thousands of thaw lakes and ponds are impacted by changes in temperature, precipitation, thawing permafrost, and human activity. Although summer in the Arctic is short, incoming solar radiation and lake evaporation are relatively high, and both factors play a significant role in the landscape water balance. Furthermore, lake evaporation is anticipated to increase as the ice-free season lengthens and water temperatures become warmer. To improve our understanding …

Abiotic Stress Responses In Photosynthetic Organisms, Joseph Msanne

School of Natural Resources: Dissertations, Theses, and Student Research

Cellular and molecular aspects of abiotic stress responses in Arabidopsis thaliana subjected to cold, drought, and high salinity and in two photosynthetic green alga, Chlamydomonas reinhardtii and Coccomyxa sp. C-169, subjected to nitrogen deprivation were investigated. Cold, drought, and high salinity can negatively affect plant growth and crop production. The first research aimed at determining the physiological functions of the stress-responsive Arabidopsis thaliana RD29A and RD29B genes. Cold, drought, and salt induced both genes; the promoter of RD29Awas found to be more responsive to drought and cold stresses, whereas the promoter of RD29B was highly responsive to salt stress. …

Climate Change And Climate Variability: El Salvador – Impacts On Productivity Of Grain Crops And Opportunities For Management And Improvement, P. V. Vara Prasad

INTSORMIL Presentations

1. Climate change and climate variability (past and future).

2. Climate change and variability in El Salvador (climate models).

3. Impact of temperature on grain yield of dry bean, maize and sorghum in El Salvador (crop simulation models).

4. Effects of temperature, drought and/or carbon dioxide: experimental evidence (response of grain sorghum, maize and dry bean).

5. Opportunities for crop management and genetic improvement.

Estimating Oil Concentration And Flow Rate With Calibrated Vessel-Mounted Acoustic Echo Sounders, Thomas C. Weber, Alex De Robertis, Shep Smith, Samuel F. Greenaway, Larry A. Mayer, Glen Rice

Center for Coastal and Ocean Mapping

As part of a larger program aimed at evaluating acoustic techniques for mapping the distribution of subsurface oil and gas associated with the Deepwater Horizon-Macondo oil spill, observations were made on June 24 and 25, 2010 using vessel-mounted calibrated single-beam echo sounders on the National Oceanic and Atmospheric Administration ship Thomas Jefferson. Coincident with visual observations of oil at the sea surface, the 200-kHz echo sounder showed anomalously high-volume scattering strength in the upper 200 m on the western side of the wellhead, more than 100 times higher than the surrounding waters at 1,800-m distance from the wellhead, …

Aquatic Plant Surveys In The Bureau Of Land Management, Medford District, 2010-2011, Mark D. Sytsma, Rich Miller, Vanessa Morgan

Center for Lakes and Reservoirs Publications and Presentations

The introduction of invasive aquatic plant species (IAPS) can cause significant ecological and economic harm. IAPS can displace native aquatic plant species, impair recreation, and degrade water quality. Early detection of new invasions can improve chances for successful eradication or containment to reduce the risk of IAPS spread. The Oregon Department of Agriculture (ODA) lists the most egregious offenders as “Noxious Weeds” which are defined as plants classified by the Oregon State Weed Board that are injurious to public health, agriculture, recreation, wildlife, or any public or private property (ODA 2011).

Several IAPS classified as noxious have been detected within …

Quantifying Burned Area For North American Forests: Implications For Direct Reduction Of Carbon Stocks, Eric S. Kasischke, Tatiana Loboda, Louis Giglio, Nancy H. F. French, E. E. Hoy, Bernardus De Jong, David Riano

Michigan Tech Research Institute Publications

A synthesis was carried out to analyze information available to quantify fire activity and burned area across North America, including a comparison of different data sources and an assessment of how variations in burned area estimate impact carbon emissions from fires. Data sets maintained by fire management agencies provide the longest record of burned area information. Canada and Alaska have the most well developed data sets consisting of the perimeters of large fires (>200 ha) going back to 1959 and 1950, respectively. A similar data set back to 1980 exists for the Conterminous U.S., but contains data only from …

Model Comparisons For Estimating Carbon Emissions From North American Wildland Fire, Nancy H. F. French, Willam J. De Groot, Liza K. Jenkins, Brendan M. Rogers, Ernesto Alvarado, Brian Amiro, Bernardus De Jong, Scott Goetz, Elizabeth Hoy, Edward Hyer, Robert Keane, B. E. Law, Donald Mckenzie, Steven G. Mcnulty, Roger Ottmar, Diego R. Perez-Salicrup, James Randerson, Kevin M. Robertson, Merritt Turetsky

Michigan Tech Research Institute Publications

Research activities focused on estimating the direct emissions of carbon from wildland fires across North America are reviewed as part of the North American Carbon Program disturbance synthesis. A comparison of methods to estimate the loss of carbon from the terrestrial biosphere to the atmosphere from wildland fires is presented. Published studies on emissions from recent and historic time periods and five specific cases are summarized, and new emissions estimates are made using contemporary methods for a set of specific fire events. Results from as many as six terrestrial models are compared. We find that methods generally produce similar results …

Vulnerability Of High Latitude Soil Organic Carbon In North America To Disturbance, Guido Grosse, Jennifer Harden, Merritt Turetsky, David A. Mcguire, Philip Camill, Charles Tarnocai, Steve Frolking, Edward A.G. Schuur, Torre Jorgenson, Sergei Marchenko, Vladimir Romanovsky, Kimberly P. Wickland, Nancy H. F. French, Mark Waldrop, Laura Bourgeau-Chavez, Robert G. Striegl

Michigan Tech Research Institute Publications

This synthesis addresses the vulnerability of the North American high-latitude soil organic carbon (SOC) pool to climate change. Disturbances caused by climate warming in arctic, subarctic, and boreal environments can result in significant redistribution of C among major reservoirs with potential global impacts. We divide the current northern high-latitude SOC pools into (1) near-surface soils where SOC is affected by seasonal freeze-thaw processes and changes in moisture status, and (2) deeper permafrost and peatland strata down to several tens of meters depth where SOC is usually not affected by short-term changes. We address key factors (permafrost, vegetation, hydrology, paleoenvironmental history) …

Emergent Behavior In A Coupled Economic And Coastline Model For Beach Nourishment, Eli D. Lazarus, D E. Mcnamara, M D. Smith, S Gopalakrishnan, A B. Murray

Publications

Developed coastal areas often exhibit a strong systemic coupling between shoreline dynamics and economic dynamics. "Beach nourishment", a common erosion-control practice, involves mechanically depositing sediment from outside the local littoral system onto an actively eroding shoreline to alter shoreline morphology. Natural sediment-transport processes quickly rework the newly engineered beach, causing further changes to the shoreline that in turn affect subsequent beach-nourishment decisions. To the limited extent that this landscape/economic coupling has been considered, evidence suggests that towns tend to employ spatially myopic economic strategies under which individual towns make isolated decisions that do not account for their neighbors. What happens …

Randomization Tests For Quantifying Species Importance To Ecosystem Function, Nicholas J. Gotelli, Werner Ulrich, Fernando T. Maestre

College of Arts and Sciences Faculty Publications

1. Quantifying the contribution of different species to ecosystem function is an important challenge. We introduce simple randomization tests (and software) for quantifying the average effect of species on ecosystem variables measured in multiple plots with and without the presence of a particular species. These randomization tests formalize the analysis of uncontrolled 'natural experiments' and quantify species effects in standardized deviation units. 2.We tested the method with data on ecosystem function in biological soil crust assemblages of lichens in semi-arid gypsum outcrops in central Spain. In sixty-three 50cm×50cm sample plots, we measured the presence and percentage cover of 17 species …

Underestimating The Costs Of Conservation In Southeast Asia, David P. Edwards, Brendan Fisher, Xingli Giam, David S. Wilcove

Rubenstein School of Environment and Natural Resources Faculty Publications

No abstract provided.

The Relation Between Black Hole Mass And Host Spheroid Stellar Mass Out To Z~2, Vardha N. Bennert, Matthew A. Auger, Tommaso Treu, Jong-Hak Woo, Matthew A. Malkan

Physics

We combine Hubble Space Telescope images from the Great Observatories Origins Deep Survey with archival Very Large Telescope and Keck spectra of a sample of 11 X-ray-selected broad-line active galactic nuclei in the redshift range 1 < z < 2 to study the black-hole-mass-stellar-mass relation out to a look-back time of 10 Gyr. Stellar masses of the spheroidal component (M _sph, ) are derived from multi-filter surface photometry. Black hole masses (M _BH) are estimated from the width of the broad Mg II emission line and the 3000 Å nuclear luminosity. Comparing with a uniformly measured local sample and taking into account selection effects, we find evolution in the form M _BH/M _sph, (1 + z)^{1.96 …}

Morphological Features Of Elongated-Anisotropic Magnetosome Crystals In Magnetotactic Bacteria Of The Nitrospirae Phylum And The Deltaproteobacteria Class, Christopher T. Lefèvre, Mihály Pósfai, Fernanda Abreu, Ulysses Lins, Richard B. Frankel, Dennis A. Bazlinski

Physics

High resolution transmission electron microscopy was used to study the crystallographic habits of the elongated magnetite crystals, variously described as bullet-, tooth- or arrowhead-shaped, in two recently described, uncultured, magnetotactic bacteria belonging to the Nitrospirae phylum designated Candidatus Magnetoovum mohavensis strain LO-1, and Candidatus Thermomagnetovibrio paiutensis strain HSMV-1; and a cultured sulfate-reducing magnetotactic bacterium of the Deltaproteobacteria class of the Proteobacteria phylum designated strain AV-1. The elongation axes of the magnetosomes do not coincide with the easy magnetization axis (which is [111]) but they are parallel to [100] in LO-1 and AV-1 and parallel to [110] in HSMV-1. In all …

Personality Dimensions And Temperaments Of Engineering Professors And Students – A Survey, Arif Raza, Zaka Ulmustafa, Luiz Fernando Capretz

Electrical and Computer Engineering Publications

This research work aims to study personality profiles and temperaments of Pakistani software engineering professors and students. In this survey we have collected personality profiles of 18 professors and 92 software engineering students. According to the Myers-Briggs Type Indicator (MBTI) instrument, the most prominent personality type among professors as well as among students is a combination of Introversion, Sensing, Thinking, and Judging (ISTJ). The study shows ITs (Introverts and Thinking) and IJs (Introverts and Judging) are the leading temperaments among the professors. About the students’ data, the results of the study indicate SJs (Sensing and Judging) and ISs (Introverts and …

Overview Of Contrast Data Mining As A Field And Preview Of An Upcoming Book, Guozhu Dong, James Bailey

Kno.e.sis Publications

This report provides an overview of the field of contrast data mining and its applications, and offers a preview of an upcoming book on the topic. The importance of contrasting is discussed and a brief survey is given covering the following topics: general definitions and terminology for contrast patterns, representative contrast pattern mining algorithms, applications of contrast mining for fundamental data mining tasks such as classification and clustering, applications of contrast mining in bioinformatics, medicine, blog analysis, image analysis and subgroup mining, results on contrast based dataset similarity measure, and on analyzing item interaction in contrast patterns, and open research …