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2015

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Articles 2281 - 2310 of 12617

Full-Text Articles in Physical Sciences and Mathematics

Identifying Student Difficulties With Heat Engines, Entropy, And The Carnot Cycle, Trevor I. Smith, Warren M. Christensen, Donald B. Mountcastle, John R. Thompson Sep 2015

Identifying Student Difficulties With Heat Engines, Entropy, And The Carnot Cycle, Trevor I. Smith, Warren M. Christensen, Donald B. Mountcastle, John R. Thompson

Physics and Astronomy Faculty Scholarship

We report on several specific student difficulties regarding the second law of thermodynamics in the context of heat engines within upper-division undergraduate thermal physics courses. Data come from ungraded written surveys, graded homework assignments, and videotaped classroom observations of tutorial activities. Written data show that students in these courses do not clearly articulate the connection between the Carnot cycle and the second law after lecture instruction. This result is consistent both within and across student populations. Observation data provide evidence for myriad difficulties related to entropy and heat engines, including students’ struggles in reasoning about situations that are physically impossible …

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Addressing Confounding In Predictive Models With An Application To Neuroimaging, Kristin A. Linn, Bilwaj Gaonkar, Jimit Doshi, Christos Davatzikos, Russell T. Shinohara Sep 2015

Addressing Confounding In Predictive Models With An Application To Neuroimaging, Kristin A. Linn, Bilwaj Gaonkar, Jimit Doshi, Christos Davatzikos, Russell T. Shinohara

UPenn Biostatistics Working Papers

Understanding structural changes in the brain that are caused by a particular disease is a major goal of neuroimaging research. Multivariate pattern analysis (MVPA) comprises a collection of tools that can be used to understand complex disease effects across the brain. We discuss several important issues that must be considered when analyzing data from neuroimaging studies using MVPA. In particular, we focus on the consequences of confounding by non-imaging variables such as age and sex on the results of MVPA. After reviewing current practice to address confounding in neuroimaging studies, we propose an alternative approach based on inverse probability weighting. …

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Control-Group Feature Normalization For Multivariate Pattern Analysis Using The Support Vector Machine, Kristin A. Linn, Bilwaj Gaonkar, Jimit Doshi, Christos Davatzikos, Russell T. Shinohara Sep 2015

Control-Group Feature Normalization For Multivariate Pattern Analysis Using The Support Vector Machine, Kristin A. Linn, Bilwaj Gaonkar, Jimit Doshi, Christos Davatzikos, Russell T. Shinohara

UPenn Biostatistics Working Papers

Normalization of feature vector values is a common practice in machine learning. Generally, each feature value is standardized to the unit hypercube or by normalizing to zero mean and unit variance. Classification decisions based on support vector machines (SVMs) or by other methods are sensitive to the specific normalization used on the features. In the context of multivariate pattern analysis using neuroimaging data, standardization effectively up- and down-weights features based on their individual variability. Since the standard approach uses the entire data set to guide the normalization it utilizes the total variability of these features. This total variation is inevitably …

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Mossbauer Effect, Ronald Lovett Sep 2015

Mossbauer Effect, Ronald Lovett

Topics in Quantum Mechanics

No abstract provided.

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Evaluation Of Anisole-Substituted Boron Difluoride Formazanate Complexes For Fluorescence Cell Imaging, Ryan R. Maar, Stephanie M. Barbon, Neha Sharma, Hilary Groom, Leonard G. Luyt, Joe Gilroy Sep 2015

Evaluation Of Anisole-Substituted Boron Difluoride Formazanate Complexes For Fluorescence Cell Imaging, Ryan R. Maar, Stephanie M. Barbon, Neha Sharma, Hilary Groom, Leonard G. Luyt, Joe Gilroy

Chemistry Publications

The evaluation of three subclasses of boron difluoride formazanate complexes bearing o-, m-, and p-anisole N-aryl substituents (Ar) as readily accessible alternatives to boron dipyrromethene (BODIPY) dyes for cell imaging applications is described. While the wavelengths of maximum absorption (lmax) and emission (lem) observed for each subclass of complexes, which differed by their carbon-bound substituents (R), were similar, the emission quantum yields for 7a-c (R = cyano) were enhanced relative to 8a-c (R = nitro) and 9a-c (R = phenyl). Complexes 7a-c and 8a-c were also significantly …

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Student Understanding Of The Boltzmann Factor, Trevor I. Smith, Donald B. Mountcastle, John R. Thompson Sep 2015

Student Understanding Of The Boltzmann Factor, Trevor I. Smith, Donald B. Mountcastle, John R. Thompson

College of Science & Mathematics Departmental Research

We present results of our investigation into student understanding of the physical significance and utility of the Boltzmann factor in several simple models. We identify various justifications, both correct and incorrect, that students use when answering written questions that require application of the Boltzmann factor. Results from written data as well as teaching interviews suggest that many students can neither recognize situations in which the Boltzmann factor is applicable nor articulate the physical significance of the Boltzmann factor as an expression for multiplicity, a fundamental quantity of statistical mechanics. The specific student difficulties seen in the written data led us …

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Identifying Student Difficulties With Entropy, Heat Engines, And The Carnot Cycle, Trevor I. Smith, Warren M. Christensen, Donald B. Mountcastle, John R. Thompson Sep 2015

Identifying Student Difficulties With Entropy, Heat Engines, And The Carnot Cycle, Trevor I. Smith, Warren M. Christensen, Donald B. Mountcastle, John R. Thompson

College of Science & Mathematics Departmental Research

We report on several specific student difficulties regarding the second law of thermodynamics in the context of heat engines within upper-division undergraduate thermal physics courses. Data come from ungraded written surveys, graded homework assignments, and videotaped classroom observations of tutorial activities. Written data show that students in these courses do not clearly articulate the connection between the Carnot cycle and the second law after lecture instruction. This result is consistent both within and across student populations. Observation data provide evidence for myriad difficulties related to entropy and heat engines, including students’ struggles in reasoning about situations that are physically impossible …

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4th International Symposium On Sensor Science (I3s2015): Conference Report, Peter Seitz, Debbie G. Senesky, Michael J. Schöning, Peter C. Hauser, Roland Moser, Hans Peter Herzig, Assefa M. Melesse, Patricia A. Broderick, Patrick Thomas Eugester Sep 2015

4th International Symposium On Sensor Science (I3s2015): Conference Report, Peter Seitz, Debbie G. Senesky, Michael J. Schöning, Peter C. Hauser, Roland Moser, Hans Peter Herzig, Assefa M. Melesse, Patricia A. Broderick, Patrick Thomas Eugester

Department of Earth and Environment

No abstract provided.

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Momentum Flux Estimates Accompanying Multi-Scale Gravity Waves Over Mt. Cook, New Zealand On 13 July 2014 During The Deepwave Campaign, Katrina Bossert, David C. Fritts, Pierre-Dominique Pautet, Bifford P. Williams, Michael J. Taylor, Bernd Kaifler, Andrea Dornbrack, Iain M. Reid, Damian J. Murphy, Andrew J. Spargo, Andrew D. Mackinnon Sep 2015

Momentum Flux Estimates Accompanying Multi-Scale Gravity Waves Over Mt. Cook, New Zealand On 13 July 2014 During The Deepwave Campaign, Katrina Bossert, David C. Fritts, Pierre-Dominique Pautet, Bifford P. Williams, Michael J. Taylor, Bernd Kaifler, Andrea Dornbrack, Iain M. Reid, Damian J. Murphy, Andrew J. Spargo, Andrew D. Mackinnon

Publications

Observations performed with a Rayleigh lidar and an Advanced Mesosphere Temperature Mapper aboard the National Science Foundation/National Center for Atmospheric Research Gulfstream V research aircraft on 13 July 2014 during the Deep Propagating Gravity Wave Experiment (DEEPWAVE) measurement program revealed a large-amplitude, multiscale gravity wave (GW) environment extending from ~20 to 90 km on flight tracks over Mount Cook, New Zealand. Data from four successive flight tracks are employed here to assess the characteristics and variability of the larger- and smaller-scale GWs, including their spatial scales, amplitudes, phase speeds, and momentum fluxes. On each flight, a large-scale mountain wave (MW) …

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Computing In Algebraic Closures Of Finite Fields, Javad Doliskani Sep 2015

Computing In Algebraic Closures Of Finite Fields, Javad Doliskani

Electronic Thesis and Dissertation Repository

We present algorithms to construct and perform computations in algebraic closures of finite fields. Inspired by algorithms for constructing irreducible polynomials, our approach for constructing closures consists of two phases; First, extension towers of prime power degree are built, and then they are glued together using composita techniques. To be able to move elements around in the closure we give efficient algorithms for computing isomorphisms and embeddings. In most cases, our algorithms which are based on polynomial arithmetic, rather than linear algebra, have quasi-linear complexity.

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Monoclinic Optical Constants, Birefringence, And Dichroism Of Slanted Titanium Nanocolumns Determined By Generalized Ellipsometry, Daniel Schmidt, Benjamin Booso, Tino Hofmann, Eva Schubert, Andrew Sarangan, Mathias Schubert Sep 2015

Monoclinic Optical Constants, Birefringence, And Dichroism Of Slanted Titanium Nanocolumns Determined By Generalized Ellipsometry, Daniel Schmidt, Benjamin Booso, Tino Hofmann, Eva Schubert, Andrew Sarangan, Mathias Schubert

Andrew Sarangan

Generalized spectroscopic ellipsometry determines the principal monoclinic optical constants of thin films consisting of slanted titanium nanocolumns deposited by glancing angle deposition under 85° incidence and tilted from the surface normal by 47°. Form birefringence measured for wavelengths from 500 to 1000 nm renders the Ti nanocolumns monoclinic absorbing crystals with c-axis along the nanocolumns, b-axis parallel to the film interface, and 67.5° monoclinic angle between the aand c-axes. The columnar thin film reveals anomalous optical dispersion, extreme birefringence, strong dichroism, and differs completely from bulk titanium. Characteristic bulk interband transitions are absent in the spectral range investigated.

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U.S. Drought Monitor, September 22, 2015, Eric Luebehusen Sep 2015

U.S. Drought Monitor, September 22, 2015, Eric Luebehusen

United States Agricultural Commodities in Drought Archive

Drought map of U.S. for September 22, 2015 (9/22/15) plus: U.S. crop areas experiencing drought (map), Approximate percentage of crop located in drought, by state (bar graph), Percent of crop area located in drought, past 52 weeks (line graph) for: Corn, Soybeans, Hay, Cattle, Winter wheat.

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Dependence Of Electrostatic Field Strength On Voltage Ramp Rates For Spacecraft Materials, Krysta Moser, Allen Andersen, Jr Dennison Sep 2015

Dependence Of Electrostatic Field Strength On Voltage Ramp Rates For Spacecraft Materials, Krysta Moser, Allen Andersen, Jr Dennison

Presentations

Previous tests done by the USU Materials Physics Group (MPG) using our electrostatic discharge (ESD) custom vacuum chamber have found that, for the polymeric materials polyimide and low density polyethylene (LDPE), the electrostatic field strength at breakdown depends on the voltage ramp rate applied across the materials. At ramp rates an order of magnitude lower than the maximum recommended rate of 500 V/s, the breakdown electrostatic field strength was also found to be significantly lower. The data from these tests were compared to a microscopic mean field theory for dielectric breakdown in highly disordered insulating materials. We present new ramp …

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A Multilevel Analysis Of Neighborhood Socioeconomic Effect On Preterm Births In Georgia, Usa, Wei Tu, Jun Tu, Stuart H. Tedders Sep 2015

A Multilevel Analysis Of Neighborhood Socioeconomic Effect On Preterm Births In Georgia, Usa, Wei Tu, Jun Tu, Stuart H. Tedders

School of Earth, Environment, and Sustainability Faculty Publications

This study estimates the neighborhood socioeconomic status (SES) effect on the risk of preterm birth (PTB) using multilevel regression (MLR) models. Birth data retrieved from year 2000 and 2010 Georgia Vital Records were linked to their respective census tracts. Principle component analysis (PCA) was performed on nine selected census variables and the first two principal components (Fac1 and Fac2) were used to represent the neighborhood-level SES in the MLR models. Two-level random intercept MLR models were specified using 122,744 and 112,578 live and singleton births at the individual level and 1613 and 1952 census tracts at the neighborhood level, for …

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On The Analysis Of Some Recursive Equations In Probability., Arunangshu Biswas Dr. Sep 2015

On The Analysis Of Some Recursive Equations In Probability., Arunangshu Biswas Dr.

Doctoral Theses

This thesis deals with recursive systems used in theoretical and applied probability. Recursive systems are stochastic processes {Xn}n≥1 where the Xn depends on the earlier Xn−1 and also on some increment process which is uncorrelated with the process Xn. The simplest example of a recursive system is the Random Walk, whose properties have been extensively studied. Mathematically a recursive system takes the form Xn = f(Xn−1, n), is the increment/ innovation procedure and f(·, ·) is a function on the product space of xn and n. We first consider a recursive system called Self-Normalized sums (SNS) corresponding to a sequence …

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Experimentally Quantifying The Advantages Of Weak-Value-Based Metrology, Gerardo I. Viza, Julián Martínez-Rincón, Gabriel B. Alves, Andrew N. Jordan, John C. Howell Sep 2015

Experimentally Quantifying The Advantages Of Weak-Value-Based Metrology, Gerardo I. Viza, Julián Martínez-Rincón, Gabriel B. Alves, Andrew N. Jordan, John C. Howell

Mathematics, Physics, and Computer Science Faculty Articles and Research

We experimentally investigate the relative advantages of implementing weak-value-based metrology versus standard methods. While the techniques outlined herein apply more generally, we measure small optical beam deflections both using a Sagnac interferometer with a monitored dark port (the weak-value-based technique), and by focusing the entire beam to a split detector (the standard technique). By introducing controlled external transverse detector modulations and transverse beam deflection momentum modulations, we quantify the mitigation of these sources in the weak-value-based experiment versus the standard focusing experiment. The experiments are compared using a combination of deterministic and stochastic methods. In all cases, the weak-value technique …

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Charging Level And Deposition Of Droplets In Electrostatic Painting, Husam Osman Sep 2015

Charging Level And Deposition Of Droplets In Electrostatic Painting, Husam Osman

Electronic Thesis and Dissertation Repository

The process of electrostatic painting has become a very important method of coating in a wide range of industrial applications including those used in the automobile industry. The general principle of spray coating is to deposit liquid droplets or solid powder particles on coated targets having various shapes. The electrostatic coating process consists of three main stages: droplet formation and charging, transportation and deposition. The complication of this process is caused by various factors, such as the physical properties of the material to be used, the appropriate electrical and mechanical conditions and the target surface to be coated, which affects …

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Sulfur, Iron And Carbon Cycling Following Hydrological Restoration Of Acidic Freshwater Wetlands, Scott Johnston, Edward Burton, Thor Aaso, Gerard Tuckerman Sep 2015

Sulfur, Iron And Carbon Cycling Following Hydrological Restoration Of Acidic Freshwater Wetlands, Scott Johnston, Edward Burton, Thor Aaso, Gerard Tuckerman

Associate Professor Edward D Burton

Freshwater re-flooding is a relatively novel approach to remediate drained acid sulfate soil (ASS) wetlands. This study documents the geochemical consequences of restoring freshwater re-flooding for contemporary reduced inorganic sulfur (RIS) and iron species in two coastal floodplain ASS wetlands. Re-flooding has established predominantly reducing/suboxic conditions and encouraged organic carbon accumulation in surface sediments (~ 20–30%). The pH of former sulfuric horizons has increased by ~ 2–3 units, partly in response to alkalinity generation from anaerobic metabolism of organic carbon coupled with Fe(III) and SO42 − reduction. Despite considerable sulfidisation, reactive Fe (FeR; sum of 1 M HCl and citrate–dithionite …

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Arsenic Mobility During Flooding Of Contaminated Soil: The Effect Of Microbial Sulfate Reduction, Edward Burton, Scott Johnston, Benjamin Kocar Sep 2015

Arsenic Mobility During Flooding Of Contaminated Soil: The Effect Of Microbial Sulfate Reduction, Edward Burton, Scott Johnston, Benjamin Kocar

Associate Professor Edward D Burton

In floodplain soils, As may be released during flooding-induced soil anoxia, with the degree of mobilization being affected by microbial redox processes such as the reduction of As(V), Fe(III), and SO42–. Microbial SO42– reduction may affect both Fe and As cycling, but the processes involved and their ultimate consequences on As mobility are not well understood. Here, we examine the effect of microbial SO42 reduction on solution dynamics and solid-phase speciation of As during flooding of an As-contaminated soil. In the absence of significant levels of microbial SO42– reduction, flooding caused increased Fe(II) and As(III) concentrations over a 10 week …

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Seawater Inundation Of Coastal Floodplain Sediments: Short-Term Changes In Surface Water And Sediment Geochemistry, Vanessa Wong, Scott Johnston, Edward Burton, Phillip Hirst, Leigh Sullivan, Richard Bush, Mark Blackford Sep 2015

Seawater Inundation Of Coastal Floodplain Sediments: Short-Term Changes In Surface Water And Sediment Geochemistry, Vanessa Wong, Scott Johnston, Edward Burton, Phillip Hirst, Leigh Sullivan, Richard Bush, Mark Blackford

Associate Professor Edward D Burton

Coastal floodplains are highly vulnerable to seawater inundation as a result of storm surge and sea-level rise due to their low elevation and proximity to the coastline. Intact soil cores from a levee, acid-sulfate soil scald and four backswamp sites on a coastal floodplain in eastern Australia were inundated with artificial seawater treatments (0%, 50% and 100%) for 14 days to examine the short term consequences for surface water and floodplain sediment geochemistry. All sites displayed an initial decrease in surface water pH following inundation with 50% and 100% seawater. In addition, higher concentrations of trace metals (Al, Fe, Mn, …

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Capacity Planning With Financial And Operational Hedging In Low‐Cost Countries, Lijian Chen, Shanling Li, Letian Wang Sep 2015

Capacity Planning With Financial And Operational Hedging In Low‐Cost Countries, Lijian Chen, Shanling Li, Letian Wang

Lance (Lijian) Chen

The authors of this paper outline a capacity planning problem in which a risk-averse firm reserves capacities with potential suppliers that are located in multiple low-cost countries. While demand is uncertain, the firm also faces multi-country foreign currency exposures. This study develops a mean-variance model that maximizes the firm’s optimal utility and derives optimal utility and optimal decisions in capacity and financial hedging size. The authors show that when demand and exchange rate risks are perfectly correlated, a risk- averse firm, by using financial hedging, will achieve the same optimal utility as a risk-neutral firm. In this paper as well, …

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A Simulation-Based Approach To Solve A Specific Type Of Chance Constrained Optimization, Lijian Chan Sep 2015

A Simulation-Based Approach To Solve A Specific Type Of Chance Constrained Optimization, Lijian Chan

Lance (Lijian) Chen

We solve the chance constrained optimization with convex feasible set through approximating the chance constraint by another convex smooth function. The approximation is based on the numerical properties of the Bernstein polynomial that is capable of effectively controlling the approximation error for both function value and gradient. Thus, we adopt a first-order algorithm to reach a satisfactory solution which is expected to be optimal. When the explicit expression of joint distribution is not available, we then use Monte Carlo approach to numerically evaluate the chance constraint to obtain an optimal solution by probability. Numerical results for known problem instances are …

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Re-Solving Stochastic Programming Models For Airline Revenue Management, Lijian Chen, Tito Homem-De-Mello Sep 2015

Re-Solving Stochastic Programming Models For Airline Revenue Management, Lijian Chen, Tito Homem-De-Mello

Lance (Lijian) Chen

We study some mathematical programming formulations for the origin-destination model in airline revenue management. In particular, we focus on the traditional probabilistic model proposed in the literature. The approach we study consists of solving a sequence of two-stage stochastic programs with simple recourse, which can be viewed as an approximation to a multi-stage stochastic programming formulation to the seat allocation problem. Our theoretical results show that the proposed approximation is robust, in the sense that solving more successive two-stage programs can never worsen the expected revenue obtained with the corresponding allocation policy. Although intuitive, such a property is known not …

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Ancillary Service Capacity Optimization For Both Electric Power Suppliers And Independent System Operator, Lijian Chen, Dengfeng Sun, Guang Li Sep 2015

Ancillary Service Capacity Optimization For Both Electric Power Suppliers And Independent System Operator, Lijian Chen, Dengfeng Sun, Guang Li

Lance (Lijian) Chen

Ancillary Services (AS) in electric power industry are critical to support the transmission of energy from generators to load demands while maintaining reliable operation of transmission systems in accordance with good utility practice. The ancillary services are procured by the independent system operator (ISO) through a process called the market clearing process which can be modeled by the partial equilibrium from the ends of ISO. There are two capacity optimization problems for both Market participants (MP) and Independent System Operator (ISO). For a market participant, the firm needs to determine the capacity allocation plan for various AS to pursue operating …

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Capacity-Driven Pricing Mechanism In Special Service Industries, Lijian Chen, Suraj M. Alexander Sep 2015

Capacity-Driven Pricing Mechanism In Special Service Industries, Lijian Chen, Suraj M. Alexander

Lance (Lijian) Chen

We propose a capacity driven pricing mechanism for several service industries in which the customer behavior, the price demand relationship, and the competition are significantly distinct from other industries. According our observation, we found that the price demand relationship in these industries cannot be modeled by fitted curves; the customers would neither plan in advance nor purchase the service strategically; and the competition would be largely local. We analyze both risk neutral and risk aversion pricing models and conclude the proposed capacity driven model would be the optimal solution under mild assumptions. The resulting pricing mechanism has been implemented at …

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A Scientific Basis For Regulating Deep-Sea Fishing By Depth, Jo Clarke, Rosanna Milligan, David M. Bailey, Francis Neat Sep 2015

A Scientific Basis For Regulating Deep-Sea Fishing By Depth, Jo Clarke, Rosanna Milligan, David M. Bailey, Francis Neat

Marine & Environmental Sciences Faculty Articles

The deep sea is the world’s largest ecosystem, with high levels of biodiversity and many species that exhibit life-history characteristics thatmake them vulnerable to high levels of exploitation. Many fisheries in the deep sea have a track record of being unsustainable. In the northeast Atlantic, there has been a decline in the abundance of commercial fish species since deep-sea fishing commenced in the 1970s. Current management is by effort restrictions and total allowable catch (TAC), but there remain problems with compliance and high levels of bycatch of vulnerable species such as sharks. The European Union is currently considering new legislation …

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A Simple Method To Estimate The Time-Dependent Roc Curve Under Right Censoring, Liang Li, Bo Hu, Tom Greene Sep 2015

A Simple Method To Estimate The Time-Dependent Roc Curve Under Right Censoring, Liang Li, Bo Hu, Tom Greene

COBRA Preprint Series

The time-dependent Receiver Operating Characteristic (ROC) curve is often used to study the diagnostic accuracy of a single continuous biomarker, measured at baseline, on the onset of a disease condition when the disease onset may occur at different times during the follow-up and hence may be right censored. Due to censoring, the true disease onset status prior to the pre-specified time horizon may be unknown on some patients, which causes difficulty in calculating the time-dependent sensitivity and specificity. We study a simple method that adjusts for censoring by weighting the censored data by the conditional probability of disease onset prior …

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Multifractal And Monofractal Scaling In A Laboratory Magnetohydrodynamic Turbulence Experiment, D. A. Schaffner, Michael R. Brown Sep 2015

Multifractal And Monofractal Scaling In A Laboratory Magnetohydrodynamic Turbulence Experiment, D. A. Schaffner, Michael R. Brown

Physics & Astronomy Faculty Works

Both multifractal and monofractal scaling of structure function exponents are observed in the turbulent magnetic fluctuations of the Swarthmore Spheromak Experiment plasma. Structure function and probability distribution function (PDF) analysis exhibits multifractal scaling exponents in low frequency, inertial range fluctuations of the turbulence but monofractal scaling in higher frequency, dissipation range fluctuations. The transition from multifractal to monofractal scaling occurs rapidly suggesting a dissipation mechanism that is insensitive to turbulent structure scale size. Structure functions and PDFs are presented for both temporal and spatial measurements. Variations in the magnetic helicity in the plasma are also shown to modify multifractal scaling …

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Synergistic Effects Of Halogen Bond And Π-Π Interactions In Thiophene-Based Building Blocks, Jamey Wilson, Jon Steven Dal Williams, Chesney Petkovsek, Peyton Reves, Jonah W. Jurss, Nathan I. Hammer, Gregory S. Tschumper, Davita L. Watkins Sep 2015

Synergistic Effects Of Halogen Bond And Π-Π Interactions In Thiophene-Based Building Blocks, Jamey Wilson, Jon Steven Dal Williams, Chesney Petkovsek, Peyton Reves, Jonah W. Jurss, Nathan I. Hammer, Gregory S. Tschumper, Davita L. Watkins

Chemistry Faculty Research & Creative Works

Although recognized as a significant force in crystal engineering, halogen bonding (XB) has been scarcely investigated in "bottom-up" approaches towards organic electronics. We report, herein, the use of a thiophene-based building block, pyridyl-thiophene (Pyr-T), to achieve an assembly driven by XB and π-π stacking interactions with iodopentafluorobenzene (IPFB). Spectroscopic and thermal analysis of the co-crystal provide indirect evidence of the assembly. The combined effects of XB and π-π stacking are confirmed experimentally via X-ray crystallography. Density functional theory (DFT) computations support experimental observations. The results of the study speak to the use of halogen bond driven self-assembly in organic electronic …

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Magnetic Meridional Winds In The Thermosphere Obtained From Global Assimilation Of Ionospheric Measurements (Gaim) Model, Levan Lomidze, Ludger Scherliess, Robert W. Schunk Sep 2015

Magnetic Meridional Winds In The Thermosphere Obtained From Global Assimilation Of Ionospheric Measurements (Gaim) Model, Levan Lomidze, Ludger Scherliess, Robert W. Schunk

All Physics Faculty Publications

Thermospheric neutral winds play an important part in the dynamics of ionospheric plasma and represent one of the key inputs for ionospheric physics-based models. Yet wind measurements are scarce and generally lack global coverage and continuity. To help mitigate this shortcoming, a data assimilation model was used to estimate neutral winds in the low- and middle-latitude thermosphere. Seasonal global maps of NmF2 andhmF2 were generated from Constellation Observing System for Meteorology, Ionosphere, and Climate radio occultation measurements for geomagnetically quiet and low solar flux conditions. The maps were assimilated into the Utah State University Global Assimilation of …

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