Physical Sciences and Mathematics Commons^™

Nonparametric Variable Importance Assessment Using Machine Learning Techniques, Brian D. Williamson, Peter B. Gilbert, Noah Simon, Marco Carone

UW Biostatistics Working Paper Series

In a regression setting, it is often of interest to quantify the importance of various features in predicting the response. Commonly, the variable importance measure used is determined by the regression technique employed. For this reason, practitioners often only resort to one of a few regression techniques for which a variable importance measure is naturally defined. Unfortunately, these regression techniques are often sub-optimal for predicting response. Additionally, because the variable importance measures native to different regression techniques generally have a different interpretation, comparisons across techniques can be difficult. In this work, we study a novel variable importance measure that can …

Pure E And B Polarization Maps Via Wiener Filtering, Emory F. Bunn, Benjamin Wandelt

Physics Faculty Publications

In order to draw scientific conclusions from observations of cosmic microwave background (CMB) polarization,it is necessary to separate the contributions of the E and B components of the data. For data with incomplete sky coverage, there are ambiguous modes, which can be sourced by either E or B signals. Techniques exist for producing “pure” E and B maps, which are guaranteed to be free of cross-contamination, although the standard method, which involves constructing an eigenbasis, has a high computational cost. We show that such pure maps can be thought of as resulting from the application of a Wiener filter to …

Inside-Out Growth Or Inside-Out Quenching? Clues From Colour Gradients Of Local Galaxies, Jianhui Lian, Renbin Yan, Michael Blanton, Xu Kong

Physics and Astronomy Faculty Publications

We constrain the spatial gradient of star formation history (SFH) within galaxies using the colour gradients in NUV − u (where NUV stands for near-ultraviolet) and u − i for a local spatially resolved galaxy sample. By splitting each galaxy into an inner and an outer part, we find that most galaxies show negative gradients in these two colours. We first rule out dust extinction gradient and metallicity gradient as the dominant source for the colour gradient. Then using stellar population models, we explore variations in SFH to explain the colour gradients. As shown by our earlier work, a two-phase …

New Precision Orbits Of Bright Double-Lined Spectroscopic Binaries. X. Hd 96511, Hr 7578, And Kz Andromedae, Francis C. Fekel, Gregory W. Henry, Jocelyn Tomkin

Information Systems and Engineering Management Research Publications

From an extensive number of newly acquired radial velocities we determine the orbital elements for three late-type dwarf systems, HD 96511, HR 7578, and KZ And. The orbital periods are 18.89737 ± 0.00002, 46.81610 ± 0.00006, and 3.0329113 ± 0.0000005 days, respectively, and all three systems are eccentric, although KZ And is just barely so. We have detected lines of the secondary of HD 96511 for the first time. The orbital dimensions (a1 sin i and a2 sin i) and minimum masses (m1 sin3 i and m2 sin3 i) of the binary components all have accuracies of 0.2% or better. …

Three-Dimensional Nanomagnetism, Amalio Fernández-Pacheco, Robert Streubel, Olivier Fruchart, Riccardo Hertel, Peter Fischer, Russell P. Cowburn

Robert Streubel Papers

Magnetic nanostructures are being developed for use in many aspects of our daily life, spanning areas such as data storage, sensing and biomedicine. Whereas patterned nanomagnets are traditionally two-dimensional planar structures, recent work is expanding nanomagnetism into three dimensions; a move triggered by the advance of unconventional synthesis methods and the discovery of new magnetic effects. In three-dimensional nanomagnets more complex magnetic configurations become possible, many with unprecedented properties. Here we review the creation of these structures and their implications for the emergence of new physics, the development of instrumentation and computational methods, and exploitation in numerous applications.

Machine Learning Phases Of Strongly Correlated Fermions, Kelvin Ch'ng, Juan Carrasquilla, Roger Melko, Ehsan Khatami

Faculty Publications

Machine learning offers an unprecedented perspective for the problem of classifying phases in condensed matter physics. We employ neural network machine learning techniques to distinguish finite-temperature phases of the strongly-correlated fermions on cubic lattices. We show that a three-dimensional convolutional network trained on auxiliary field configurations produced by quantum Monte Carlo simulations of the Hubbard model can correctly predict the magnetic phase diagram of the model at the average density of one (half filling). We then use the network, trained at half filling, to explore the trend in the transition temperature as the system is doped away from half filling. …

Some Tricks In Parameter Selection For Extreme Learning Machine, Weipeng Cao, Jinzhu Gao, Zhong Ming, Shubin Cai

All Faculty Presentations - School of Engineering and Computer Science

Extreme learning machine (ELM) is a widely used neural network with random weights (NNRW), which has made great contributions to many fields. However, the relationship between the parameters and the performance of ELM has not been fully investigated yet, i.e. the impact of the number of hidden layer nodes, the randomization range of the weights between the input layer and hidden layer, the randomization range of the threshold of hidden nodes, and the type of activation functions. In this paper, eight benchmark functions are used to study this relationship. We have some interesting findings, such as more hidden layer nodes …

Understanding The Uncanny: Both Atypical Features And Category Ambiguity Provoke Aversion Toward Humanlike Robots, Megan K. Strait, Victoria A. Floerke, Wendy Ju, Keith Maddox, Jessica D. Remedios, Malte F. Jung, Heather L. Urry

Computer Science Faculty Publications and Presentations

Robots intended for social contexts are often designed with explicit humanlike attributes in order to facilitate their reception by (and communication with) people. However, observation of an “uncanny valley”—a phenomenon in which highly humanlike entities provoke aversion in human observers—has lead some to caution against this practice. Both of these contrasting perspectives on the anthropomorphic design of social robots find some support in empirical investigations to date. Yet, owing to outstanding empirical limitations and theoretical disputes, the uncanny valley and its implications for human-robot interaction remains poorly understood. We thus explored the relationship between human similarity and people's aversion toward …

Relational Values Resonate Broadly And Differently Than Intrinsic Or Instrumental Values, Or The New Ecological Paradigm, Sarah Klain, Paige Olmsted, Kai M. A. Chan, Terre Satterfield

Environment and Society Faculty Publications

Value orientations used to explain or justify conservation have been rooted in arguments about how much and in what context to emphasize the intrinsic versus instrumental value of nature. Equally prominent are characterizations of beliefs known as the New Ecological Paradigm (NEP), often used to help explain pro-environmental behaviour. A recent alternative to these positions has been identified as ‘relational value’—broadly, values linking people and ecosystems via tangible and intangible relationships to nature as well as the principles, virtues and notions of a good life that may accompany these. This paper examines whether relational values are distinct from other value …

Evidence For A Low-Temperature Magnetic Ground State In Double-Perovskite Iridates With Ir5+(5D4) Ions, Jasminka Terzic, H. Zheng, Feng Ye, H. D. Zhao, P. Schlottmann, Lance E. De Long, S. J. Yuan, Gang Cao

Physics and Astronomy Faculty Publications

We report an unusual magnetic ground state in single-crystal, double-perovskite Ba₂YIrO₆ and Sr-doped Ba₂YIrO₆ with Ir⁵⁺(5d⁴) ions. Long-range magnetic order below 1.7 K is confirmed by dc magnetization, ac magnetic susceptibility, and heat-capacity measurements. The observed magnetic order is extraordinarily delicate and cannot be explained in terms of either a low-spin S = 1 state, or a singlet J_eff = 0 state imposed by the spin-orbit interactions (SOI). Alternatively, the magnetic ground state appears consistent with a SOI that competes with comparable Hund's rule coupling and inherently large …

Okcupid Data For Introductory Statistics And Data Science Courses, Albert Y. Kim, Adriana Escobedo-Land

Mathematics Sciences: Faculty Publications

We present a data set consisting of user profile data for 59,946 San Francisco OkCupid users (a free online dating website) from June 2012. The data set includes typical user information, lifestyle variables, and text responses to 10 essay questions. We present four example analyses suitable for use in undergraduate introductory probability and statistics and data science courses that use R. The statistical and data science concepts covered include basic data visualization, exploratory data analysis, multivariate relationships, text analysis, and logistic regression for prediction.

Forensic State Acquisition From Internet Of Things (Fsaiot): A General Framework And Practical Approach For Iot Forensics Through Iot Device State Acquisition, Christopher S. Meffert, Devon R. Clark, Ibrahim Baggili, Frank Breitinger

Electrical & Computer Engineering and Computer Science Faculty Publications

IoT device forensics is a difficult problem given that manufactured IoT devices are not standardized, many store little to no historical data, and are always connected; making them extremely volatile. The goal of this paper was to address these challenges by presenting a primary account for a general framework and practical approach we term Forensic State Acquisition from Internet of Things (FSAIoT). We argue that by leveraging the acquisition of the state of IoT devices (e.g. if an IoT lock is open or locked), it becomes possible to paint a clear picture of events that have occurred. To this end, …

Cosm News, Georgia Southern University

College of Science and Mathematics News (2012-2019)

• Sigma Xi Active Recruitment

A Brief Introduction To Equi-Chordal And Equi-Isoclinic Tight Fusion Frames, Matthew C. Fickus, John Jasper, Dustin G. Mixon, Cody E. Watson

Faculty Publications

Equi-chordal and equi-isoclinic tight fusion frames (ECTFFs and EITFFs) are both types of optimal packings of subspaces in Euclidean spaces. In the special case where these subspaces are one-dimensional, ECTFFs and EITFFs both correspond to types of optimal packings of lines known as equiangular tight frames. In this brief note, we review some of the fundamental ideas and results concerning ECTFFs and EITFFs.

Ionization Enhancement And Suppression By Phase-Locked Ultrafast Pulse Pairs, David B. Foote, Y. Lin, Liang-Wen Pi, Jean Marcel Ngoko Djiokap, Anthony F. Starace, W. T. Hill

Anthony F. Starace Publications

We present the results of a study of ionization of Xe atoms by a pair of phase-locked pulses, which is characterized by interference produced by the twin peaks. Two types of interference are considered: ordinary optical interference, which changes the intensity of the composite pulse and thus the ion yield, and a quantum interference, in which the excited electron wave packets interfere. We use the measured Xe+ yield as a function of the temporal delay and/or relative phase between the peaks to monitor the interferences and compare their relative strengths. We model the interference with a pulse intensity function and …

Improved Protein Structure Reconstruction Using Secondary Structures, Contacts At Higher Distance Thresholds, And Non-Contacts, Badri Adhikari, Jianlin Cheng

Badri Adhikari

Anthropogenic Infilling Of A Bermudian Sinkhole And Its Impact On Sedimentation And Benthic Foraminifera In The Adjacent Anchialine Cave Environment, Jacquelyn N. Cresswell, Peter J. Van Hengstum, Thomas M. Iliffe, Bruce E. Williams, Gil Nolan

International Journal of Speleology

In the mid-20^th century, an inland brackish pond from Bermuda, known as Eve’s Pond, was filled with marine sediment from an adjacent coastal lagoon. At this time, an eyewitness reported “…sediment billowing out of the Green Bay Cave for days…”, which is a marine-dominated anchialine cave located proximal to the former location of Eve’s Pond (~200 m). The purpose of this study was to evaluate the potential impact of this infilling event on cave sedimentation and benthic meiofaunal communities, as proxied by the unicellular protists foraminifera that remain preserved in the sediment record. Eight sediment cores were collected from …

Holdrege: Nebraska's State Soil, University Of Nebraska - Lincoln

Conservation and Survey Division

No abstract provided.

President Bergeron's 103rd Convocation Address - "Homegoing", Katherine Bergeron

Convocation Addresses

No abstract provided.

Split-Merge Model Of Workunit Replication In Distributed Computing, Alexander Rumyantsev, Srinivas R. Chakravarthy

Industrial & Manufacturing Engineering Presentations And Conference Materials

No abstract provided.

Integrated Environment And Proximity Sensing For Uav Applications, Shawn S. Brackett

Electronic Theses and Dissertations

As Unmanned Aerial Vehicle (UAV), or “drone” applications expand, new methods for sensing, navigating and avoiding obstacles need to be developed. The project applies an Extended Kalman Filter (EKF) to a simulated quadcopter vehicle though Matlab in order to estimate not only the vehicle state but the world state around the vehicle. The EKF integrates multiple sensor readings from range sensors, IMU sensors, and radiation sensors and combines this information to optimize state estimates. The result is an estimated world map to be used in vehicle navigation and obstacle avoidance.

The simulation handles the physics behind the vehicle flight. As …

Foundations, 3, David Peak

Foundations

Our goal is to try to reconcile classical EM with the existence of photons. The electric and magnetic fields associated with EM radiation, propagating in the x -direction, obey the Maxwell wave equation: ∂²E/∂t² = c²(∂²E/∂x²).

Foundations, 1, David Peak

Foundations

Quantum mechanics is money

Text message and take a picture with your smart phone; watch a movie on your Blu-ray player; get the bar code on your bag of chips scanned; obtain an MRI image of your aching shoulder; take a ride on a maglev train. None of these—and countless other—things would be possible without quantum mechanics! Leon Lederman, Nobel Prize winning physicist, is widely quoted as saying that 1/3 of the world’s economy is due to quantum mechanics. Lederman’s estimate is actually probably too low, but what surely is the case is that computers, lasers, and superconducting magnets (to …

Many-Particle Systems, 9, David Peak

Many Particles

Superconductivity phenomenology

Superconductors are materials that exhibit zero (or close to zero) resistance to electrical currents as well as perfect diamagnetism (the Meissner Effect). When a current is started in a superconducting loop, it persists for a very long time without an applied potential difference. The resistivity of a superconductor is measured to be less than 4x10^–25 Ω-m (for comparison, the resistivity of an ordinary good conductor is about 10^–8 Ω-m), and the associated decay time for the current is estimated to be greater than 100,000 years (as opposed to about 1 µs for an ordinary good …

Many-Particle Systems, 7, David Peak

Many Particles

Electronic energy bands in crystalline solids: The finite well model

Previously, we have considered the “conduction electrons” in a metal as if they were an ideal gas in a 3D infinite well. What allows us to do that? A crystalline solid consists of a periodic array of atoms, packed so close to one another that “flow” (long range relative motion of groups of atoms) is essentially impossible. It is useful to think of a solid as a giant (rigid) molecule. The periodic structure of the atoms has profound consequences for the behavior of the solid’s electrons. While, in detail, the …

Many-Particle Systems, 2, David Peak

Many Particles

Multi-electron atoms

The rich diversity of chemical processes and structures is directly related to the diversity of electronic states of multi-electron atoms that, in turn, is dictated by the Pauli Exclusion Principle. To see how the Pauli Exclusion Principle produces atomic diversity, it is useful to begin simply, in particular, by considering the most elementary multi-electron “atom”: the hydrogen anion, H^–.

Many-Particle Systems, 3, David Peak

Many Particles

Bare essentials of statistical mechanics

Atoms are examples of many-particle systems, but atoms are extraordinarily simpler than macroscopic systems consisting of 10²⁰-10³⁰ atoms. Despite their great size, many properties of macroscopic systems depend intimately on the microscopic behavior of their microscopic constituents. The proper quantum mechanical description of an N -particle system is a wavefunction that depends on 3N coordinates (3 ways of moving, in general, for every particle) and 4N quantum numbers (3 motional quantum numbers and 1 spin quantum number for every particle). (If the “particles” are molecules there might be additional quantum …

Many-Particle Systems, 5, David Peak

Many Particles

Photons as T → 0 K

Photons are massless bosons. Because they are massless, any number of them can be added or subtracted without changing the photon system energy. (For example, a 1 eV photon can be exchanged for one hundred 0.01 eV photons, without changing system energy.) As a result, the chemical potential for photons is zero.

Many-Particle Systems, 11, David Peak

Many Particles

Quantum information

In Mn10 we discussed the rudiments of “classical computation.” Classical, conventional computation involves combinations of transistors that convert low- and high-voltage inputs into different low- and high-voltage outputs. These voltages are interpreted as the binary digits 0 and 1, i.e., as bits. How bits are changed into other bits leads to such things as text preparation and storage, numerical calculations and symbolic manipulations, image and sound generation, game playing, intercontinental communication—in short, the modern world of information.

Many-Particle Systems, 4, David Peak

Many Particles

Absolute temperature

When a system is in statistical equilibrium it can usefully be characterized by a few macroscopic variables. Temperature is one of the most important of these. The absolute temperature scale (measured in kelvins, K) has the following properties. (1) T = 0 K is the temperature of a macroscopic system found permanently in its ground state. Such a system has no excitations; it has its lowest possible energy and is completely isolated from the rest of the universe.