Digital Commons Network^™

First Low-Frequency Einstein@Home All-Sky Search For Continuous Gravitational Waves In Advanced Ligo Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

We report results of a deep all-sky search for periodic gravitational waves from isolated neutron stars in data from the first Advanced LIGO observing run. This search investigates the low frequency range of Advanced LIGO data, between 20 and 100 Hz, much of which was not explored in initial LIGO. The search was made possible by the computing power provided by the volunteers of the Einstein@Home project. We find no significant signal candidate and set the most stringent upper limits to date on the amplitude of gravitational wave signals from the target population, corresponding to a sensitivity depth of 48.7 …

First Narrow-Band Search For Continuous Gravitational Waves From Known Pulsars In Advanced Detector Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a fully coherent search, based on matched filtering, which uses the position and rotational parameters obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signal-to-noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have been developed, allowing a fully coherent search for gravitational waves from known pulsars …

Gw170608: Observation Of A 19 Solar-Mass Binary Black Hole Coalescence, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

On 2017 June 8 at 02:01:16.49 UTC, a gravitational-wave (GW) signal from the merger of two stellar-mass blackholes was observed by the two Advanced Laser Interferometer Gravitational-Wave Observatory detectors with a network signal-to-noise ratio of 13. This system is the lightest black hole binary so far observed, with component masses of 12⁺⁷ _-2M⊙⁺²_-2M⊙ (90% credible intervals). These lie in the range of measured black hole masses in low-mass X-ray binaries, thus allowing us to compare black holes detected through GWs with electromagnetic observations. The source's luminosity distance is 340⁺¹⁴⁰ _-140 corresponding to redshift -0.07 …

On The Progenitor Of Binary Neutron Star Merger Gw170817, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

On 2017 August 17 the merger of two compact objects with masses consistent with two neutron stars was discovered through gravitational-wave (GW170817), gamma-ray (GRB 170817A), and optical (SSS17a/AT 2017gfo) observations. The optical source was associated with the early-type galaxy NGC 4993 at a distance of just ∼40 Mpc, consistent with the gravitational-wave measurement, and the merger was localized to be at a projected distance of ∼2 kpc away from the galaxy's center. We use this minimal set of facts and the mass posteriors of the two neutron stars to derive the first constraints on the progenitor of GW170817 at the …

Nematic Topological Superconducting Phase In Nb-Doped Bi₂Se₃, Junying Shen, Wen-Yu He, Noah Fan Qi Yuan, Zengle Huang, Chang-Woo Cho, Seng Huat Lee, Yew San Hor, Kam Tuen Law, Rolf Lortz

Physics Faculty Research & Creative Works

A nematic topological superconductor has an order parameter symmetry, which spontaneously breaks the crystalline symmetry in its superconducting state. This state can be observed, for example, by thermodynamic or upper critical field experiments in which a magnetic field is rotated with respect to the crystalline axes. The corresponding physical quantity then directly reflects the symmetry of the order parameter. We present a study on the superconducting upper critical field of the Nb-doped topological insulator Nb_xBi₂Se₃ for various magnetic field orientations parallel and perpendicular to the basal plane of the Bi₂Se₃ layers. The …

Confined Photonic Mode Propagation Observed In Photoemission Electron Microscopy, Theodore Stenmark, Robert Campbell Word, Rolf Konenkamp

Physics Faculty Publications and Presentations

Using photoemission electron microscopy (PEEM) we present a comparative analysis of the wavelength dependence of propagating fields in a simple optical slab waveguide and a thin film photonic crystal W1-type waveguide. We utilize an interferometric imaging approach for light in the near-ultraviolet regime where a 2-photon process is required to produce photoelectron emission. The typical spatial resolution in these experiments is < 30 nm. Electromagnetic theory and finite element simulations are shown to be in good agreement with the experimental observations. Our results indicate that multiphoton PEEM is a useful sub-wavelength characterization technique in thin film optics.

Trigger And Noise Filtering Algorithms For The Lhaaso Water Cherenkov Detector Array, Xiao Jie Wang, Zhi Guo Yao, Min Zha, Ming Jun Chen, Bo Gao, De Zhi Huang, Hui Cai Li, Jin Yan Liu, Wen Ying Liao, Han Rong Wu

Physics Faculty Research & Creative Works

Introduction: The Large High Altitude Air Shower Observatory (LHAASO) will be constructed at Mt. Haizishan, Sichuan Province, China. Among several detector components of the LHAASO, the Water Cherenkov Detector Array (WCDA) is of great importance for gamma-ray astronomy from 100 GeV to 30 TeV. The single-channel counting rate of a photo- multiplier tube can reach as high as 30 -35 kHz, most of them are background noise hits from the low energy cosmic ray showers, bringing a big challenge on data transferring, data storage and event reconstruction. Methods: In this paper, a dedicated trigger scheme and a fast noise filtering …

Many-Body Quantum Dynamics In The Decay Of Bent Dark Solitons Of Bose-Einstein Condensates, Garyfallia C. Katsimiga, Simeon I. Mistakidis, G. M. Koutentakis, P. G. Kevrekidis, P. Schmelcher

Physics Faculty Research & Creative Works

The Beyond Mean-Field (MF) Dynamics Of A Bent Dark Soliton (BDS) Embedded In A Two-Dimensional Repulsively Interacting Bose-Einstein Condensate Is Explored. We Examine The Case Of A Single BDS Comparing The MF Dynamics To A Correlated Approach, The Multi-Configuration Time-Dependent Hartree Method For Bosons. Dynamical Snaking Of This Bent Structure Is Observed, Signaling The Onset Of Fragmentation Which Becomes Significant During The Vortex Nucleation. In Contrast To The MF Approximation 'filling' Of The Vortex Core Is Observed, Leading In Turn To The Formation Of Filled-Core Vortices, Instead Of The MF Vortex-Antivortex Pairs. The Resulting Smearing Effect In The Density Is …

Studies On Stable Crack Growth, Mohammed Juma Humaid Al-Ghafri

Theses

The goal of this work is to experimentally investigate the stable crack growth (SCG) fracture behavior of AISI 4340 alloy steel. A series of mode I and mixed mode SCG fracture tests were carried out on 8 mm thick compact tension (CT) specimens subjected to quasistatic loading. The wire cutting technique was used to introduce a pre-notch/ pre-crack of 0.05 mm root radius to the specimen. Five different loading angles Ψ between the loading axis and the crack surface were employed; 90° (mode I), 75°, 65°, 60° and 50°. Five different ratios of original crack length to specimen width a …

Comparing Two Alternate Assessments: Dynamic Learning Maps And Multi-State Alternate Assessment, Dana N. Sir

Seton Hall University Dissertations and Theses (ETDs)

In 2001 under No Child Left Behind, states were required to create an alternate assessment for students with significant cognitive disabilities using alternate achievement standards. In 2003, all states had created an alternate assessment. All fifty states independently developed, implemented, and revised their alternate assessments. By 2014, Dynamic Learning Map (DLM) and Multi-State Alternate Assessments (MSAA) (formerly National Center and State Collaborative)––two alternate assessments developed through consortiums consisting of state departments, universities, and organizations using federal funding––were created. At the time of this study, the DLM and MSAA were used by approximately 49% of states for their alternate assessment. This …

A Forgotten Demographic: Low-Income First-Generation College Students, Ryan Joseph-Lee Haynes

Capstone Projects and Master's Theses

The focus of this Capstone is on the need for support for low-income first-generation college students. An evidence based argument is made that these students are at a major disadvantage as compared to their counterparts. Consideration of the issue, should include the perspectives of high school students who will be the first in their family to apply and go to college. Three action options emerged from the analysis of data. Based on an analysis of the data and the relevant research literature, the researcher used what he learned to formulate an action that responded to the focus issue in a …

Strong Spatial-Temporal Patterns In Maize Yield Response To Nutrient Additions In African Smallholder Farms, Samuel Njoroge, Antonius G.T. Schut, Ken E. Giller, Shamie Zingore

All Peer-Reviewed Publications

Large variability in crop responses to macronutrient application at various spatial scales present challenges for developing effective fertilizer recommendations for crop production in smallholder farming systems of sub-Saharan Africa. We assessed maize yield responses to nitrogen (N), phosphorus (P) and potassium (K) application and evaluated relationships between crop responses to N, P and K application and soil analysis data. Nutrient omission trials were conducted on 23 farms located in Sidindi, Western Kenya, selected to be representative of the main soil and management factors in maize based systems in Siaya County. Treatments included a control and PK, NK, NP and NPK …

Secure Server-Aided Top-K Monitoring, Yujue Wang, Hwee Hwa Pang, Yanjiang Yang, Xuhua Ding

Research Collection School Of Computing and Information Systems

In a data streaming model, a data owner releases records or documents to a set of users with matching interests, in such a way that the match in interest can be calculated from the correlation between each pair of document and user query. For scalability and availability reasons, this calculation is delegated to third-party servers, which gives rise to the need to protect the integrity and privacy of the documents and user queries. In this paper, we propose a server-aided data stream monitoring scheme (DSM) to address the aforementioned integrity and privacy challenges, so that the users are able to …

Home Health Care Delivery Problem, Aldy Gunawan, Hoong Chuin Lau, Kun Lu

Research Collection School Of Computing and Information Systems

We address the Home Health Care Delivery Problem (HHCDP), which is concerned with staff scheduling in the home health care industry. The goal is to schedule health care providers to serve patients at their homes that maximizes the total collected preference scores from visited patients subject to several constraints, such as workload of the health care providers, time budget for each provider and so on. The complexity lies in the possibility of cancellation of patient bookings dynamically, and the generated schedule should attempt to patients’ preferred time windows. To cater to these requirements, we model the preference score as a …

Sem/Edx Chemical Composition Map Of Mastodon Tusk, Juliana Herran

Mastodon Tusk Project Posters

The goal of this project was to study one of the rarest objects in the collection of the UNI museum dating to the Aftonian or Yarmouth age (around 120,000 to 200,000 years old).

The tusk is 11 feet, 7.5 inches with a circumference at the proximal end of 2 feet, 2 inches.

There have been previous attempts of restoration of this tusk but there are not specific procedures on record that specify the materials or methods used during the restoration attempts with sufficient detail.

With the support of the Carver Grant awarded to the UNI museum, research teams containing students …

Energy-Dispersive X-Ray (Edx) Mapping Of Lead In Mastodon Tusk Using Sem, Nicholas Bonde, Katherine Plotzke

Mastodon Tusk Project Posters

The composition and location of lead within a prehistoric mastodon tusk was mapped using Energy Dispersive X-ray (EDX) spectroscopy analysis via a Scanning Electron Microscope (SEM). This analysis was intended to provide information on the distribution of lead throughout the tusk. Data collected from this analysis has provided insights into the sources of the lead.

Analysis Of Mammut Americanum Tusk For Asbestos, Madeline C. Roach, Joshua A. Sebree

Mastodon Tusk Project Posters

On September 23, 1933, a tusk was discovered in a gravel pit four miles south of Hampton, Iowa. After careful analysis, the tusk was determined to belong to a Mastodon americanus.1 The University of Northern Iowa museum records note that the tusk was patched with a prepared patching plaster in the 1960’s.2 In the United States at the time Alvar was the most commonly used consolidate to form a plaster. It was either mixed with acetone, alcohol and other solvents, or asbestos.3 The museum record notes indicate that the patching plaster was prepared in a can, like a spackling compound.2 …

Phase Equilibria, Compressibility, And Thermal Analysis Of Bastnaesite-(La), Richard Lee Rowland

UNLV Theses, Dissertations, Professional Papers, and Capstones

Understanding basic material properties of rare earth element (REE) bearing minerals such as the temperatures and pressures at which different phases are thermodynamically stable and how they respond to changes in temperature and pressure can assist in understanding how economically viable deposits might form, thereby potentially leading to the discovery of new deposits. Bastnaesite is the most common REE bearing mineral mined. The lanthanum-fluoride end member, bastnaesite-(La), was synthesized. Synthetic bastnaesite-(La) and lanthanum oxyfluoride was investigated using thermal analysis at ambient pressure and high temperature through the methods of thermogravimetric analysis, differential scanning calorimetry, and heated stage powder X-ray diffraction. …

Numerical Characterization Of The Flow Field And Heat Transfer Inside The Receiver Of A Parabolic Trough Solar Collector Carrying Supercritical Co2, Samad Gharehdaghimollahajloo

UNLV Theses, Dissertations, Professional Papers, and Capstones

The aim of this research is to provide a detailed numerical analysis of flow field and heat transfer inside the heat collecting element of a parabolic trough collector. The parabolic trough collector is used as the boiler in a direct Super Critical Carbon Dioxide (S-CO2) Brayton cycle.

A single collector is modeled and analyzed with different inlet conditions. The working fluid is supercritical since its pressure is increased to above critical pressure in the compressor while its temperature reaches 300 °C after passing through the recuperators and before entering the solar field. For the first time, this research considers both …

Evaluation Of A Semi-Analytical/Numerical Method For Modeling Matrix Diffusion Effects In Groundwater Chemical Transport, Noelia Susana Muskus Ruiz

All Theses

Secondary sources of contamination, such as dissolved chemicals in low permeability zones result in plume persistence and limitations for plume remediation as a consequence of the process of matrix diffusion (Mackay and Cherry, 1989; Chapman and Parker, 2005). Existing numerical transport simulators are capable of modeling matrix diffusion; however, they require fine discretization, resulting in large computational effort. An alternative approach was developed combining numerical and analytical modeling to simulate matrix diffusion effects. The semi-analytical/numerical (referred to as semi-analytical for short) approach used here was adapted from geothermal reservoir modeling of transient heat conduction in low permeability cap rocks (Vinsome …

Estimating The Location Of A Nuclear Source In A Three-Dimensional Environment With Unknown Background Radiation, Hangjin Liu

All Theses

Finding illicit nuclear sources in an urban environment plays an important role in reconnaissance research for domestic security. This work focuses on the problem of estimating the locations of radioactive sources that potentially exist in a three-dimensional search space using a network of sensors. The design of an estimation system to provide consistent surveillance is considered using drones equipped with sensors, Global Position System (GPS) devices and basic communication capabilities. In many environments, sensors cannot be placed in close proximity to the source, which makes estimating the location of a nuclear source especially difficult. In this work, we apply maximum-likelihood …

Determination Of Safe Ballasts For Anchoring Event Tents By Finite Element Analysis, Sandeep Manoharan

All Theses

Event tents are large structures made of fabric covers attached to a structural frame and poles. Every year, many temporarily installed tents are subjected to large wind conditions that lead to sliding or lift of the frame due to improper anchoring to the ground. When ballasted, as opposed to anchored using stakes that penetrate the ground, non-certified tents are generally installed without proper analysis of sufficient ballast weights, which results into tent movements and lack of safety. The objective of this thesis is to determine load factors for non-certified tents affected by high wind loads. The load requirements (load factors) …

Pyritized Cryogenian Cyanobacteria Fossils From Arctic Alaska, Kelsey R. Moore, Tanja Bosak, Francis Macdonald, Kimberly Du, Sharon A. Newman, Daniel J.G. Lahr, Sara B. Pruss

Geosciences: Faculty Publications

The Cryogenian was a time of climatic extremes, with two extended and severe global glaciations bracketing hothouse conditions. The effect of these extreme climate conditions on ocean chemistry and the marine biosphere remain poorly understood. Most of the previous studies of the fossil record from this interval focus on benthic organisms, with few examples of organisms with an inferred planktonic lifestyle and no firm evidence for photosynthetic organisms. Here, we present helically coiled, straight, and curved fossils composed of fine crystalline or framboidal pyrite in limestone samples from the Ikiakpuk formation of Arctic Alaska. These structures are morphologically identical to …

Reconstructing Time-To-Event Data From Published Kaplan–Meier Curves, Yinghui Wei, Patrick Royston

School of Engineering, Computing and Mathematics

No abstract provided.

Continuous Workout Mortgages: Efficient Pricing And Systemic Implications, Robert J. Shiller, Rafal M. Wojakowski, M. Shahid Ebrahim, Mark B. Shackleton

Cowles Foundation Discussion Papers

This paper studies the Continuous Workout Mortgage (CWM), a two in one product: a fixed rate home loan coupled with negative equity insurance, to advocate its viability in mitigating financial fragility. In order to tackle the many issues that CWMs embrace, we perform a range of tasks. We optimally price CWMs and take a systemic market-based approach, stipulating that mortgage values and payments should be linked to housing prices and adjusted downward to prevent negative equity. We illustrate that amortizing CWMs can be the efficient home financing choice for many households. We price CWMs as American option style, defaulting debt …

A Program Evaluation Of Double-Period Algebra, Jason Major

Dissertations

Students in ninth grade traditionally take algebra courses, but many students come in lacking foundational skills in mathematics. High schools have tried to solve this problem by introducing double-period algebra courses with sporadic results. During this program evaluation, I interviewed an administrator and a teacher from two different high schools about the methods they used to begin and evaluate the program; I found that student-teacher relationships were the most important factor in the effectiveness of the program. Using quantitative data was a good starting point to determine the students who would benefit from the program and who would be successful, …

Policy Advocacy For Letting Schools Be Schools, Jason Major

Dissertations

Ever since the No Child Left Behind Act of 2001, schools have been in an era of high stakes accountability around test scores, attendance, and climate and culture. This has also ushered in a wave of accountability down to teachers in the form of paperwork, mandates, and a heavy emphasis on reading and math. In Chicago Public Schools, all schools in the district are rated on the School Quality Rating Policy, which utilizes the Northwest Evaluation Association’s Measures of Academic Progress assessment to determine student growth from the spring of one year to the spring of the next. This heavy …

One Size Doesn't Fit All: Implementation Of Differentiated Instruction, Janet D. Butler

Dissertations

SIZE DOESN’T FIT ALL: IMPLEMENTATION OF DIFFERENTIATED INSTRUCTION-A CHANGE LEADERSHIP PLAN

Differentiated instruction is an approach to teaching in which educators actively plan for students' differences so that all students’ academic needs are met. It is also a process of ensuring that what a student learns, how he or she learns it, and how the student demonstrates what he or she has learned is a match for that student's readiness level, interests, and preferred mode of learning (Tomlinson, 2008). In a differentiated classroom, teachers divide their time, resources, and efforts to effectively teach students who have various backgrounds, readiness and …

Kindergarten For Equity: A Policy Advocacy Statement, Amy Houlihan

Dissertations

The urgency to close the achievement gap means it is our moral imperative to provide all children with the opportunities necessary to succeed as early as possible. Knowing the critical timing of a child’s brain development from birth to age five, we cannot afford to wait until a child is six or seven years old to begin developing their academic and social emotional capacity. This policy advocacy document supports a statewide mandate for children to attend kindergarten at age five throughout the state of Illinois. With little need for increased resources to accommodate the mandate, the social, moral and ethical …

Standards-Based Grading Within A School District Using Personalized Learning, Dywayne Hinds

Dissertations

This policy advocacy document, as part of my study, focused on my desire to implement a new grading practice within the district. This change will result in moving to a standards-based grading system from a traditional grading system. Although this would be a new practice within the district, many districts throughout the nation are making similar changes. The reason for my policy is associated with the need to measure more accurately student performance and to determine if students have mastered content specific standards within a course of study. Educators must place emphasis on the mastery of content specific standards that …