Digital Commons Network^™

Photonic Topological Chern Insulators Based On Tellegen Metacrystals, Daniel A. Jacobs, Andrey E. Miroshnichenko, Yuri S. Kivshar, Alexander B. Khanikaev

Publications and Research

We demonstrate that topologically nontrivial states of light can be engineered in periodic photonic structures containing media with a Tellegen-type bianisotropic response. Whilst in such bianisotropic materials the time-reversal symmetry is broken, they are characterized by an intrinsic magnetic order which does not require macroscopic magnetization. Our design can therefore be considered as a direct analog of the solid state Chern insulator which exhibits a topological order in the absence of an external bias. Numerical simulations of such Tellegen photonic crystals reveal the existence of one way edge transport at domain walls and perfectly conducting boundaries not sensitive to structural …

Linear Trend Detection In Serially Dependent Hydrometeorological Data Based On A Variance Correction Spearman Rho Method, Wenpeng Weng, Yuanfang Chen, Stefan Becker, Bo Liu

Publications and Research

Hydrometeorological data are commonly serially dependent and thereby deviate from the assumption of independence that underlies the Spearman rho trend test. The presence of autocorrelation will influence the significance of observed trends. Specifically, the positive autocorrelation inflates Type І errors, while it deflates the power of trend detection in some cases. To address this issue, we derive a theoretical formula and recommend an appropriate empirical formula to calculate the rho variance of dependent series. The proposed procedure of the variance correction for the Spearman rho method is capable of mitigating the effect of autocorrelation on both, Type І error and …

Evaluation Of Viirs Land Surface Temperature Using Crest-Safe Air, Snow Surface, And Soil Temperature Data, Carlos L. Pérez Díaz, Tarendra Lakhankar, Peter Romanov, Reza Khanbilvardi, Yunyue Yu

Publications and Research

In this study, the Visible Infrared Imager Radiometer Suite (VIIRS) Land Surface Temperature (LST) Environmental Data Record (EDR) was evaluated against snow surface (T-skin) and near-surface air temperature (T-air) ground observations recorded at the Cooperative Remote Sensing Science and Technology Center—Snow Analysis and Field Experiment (CREST-SAFE), located in Caribou, ME, USA during the winters of 2013 and 2014. The satellite LST corroboration of snow-covered areas is imperative because high-latitude regions are often physically inaccessible and there is a need to complement the data from the existing meteorological station networks. T-skin is not a standard meteorological parameter commonly observed at synoptic …

Nmr Studies Of Solvent-Free Ceramic Composite Polymer Electrolytes—A Brief Review, Marc B. Berman, Steven Greenbaum

Publications and Research

Polyether-based polymer electrolytes containing ceramic inorganic oxide fillers often exhibit improved mechanical and ion transport properties compared to their filler-free counterparts. The nature of local scale interactions that give rise to these enhanced properties is explored by nuclear magnetic resonance measurements.

Development And Evaluation Of A Multi-Year Fractional Surface Water Data Set Derived From Active/Passive Microwave Remote Sensing Data, Ronny Schroeder, Kyle C. Mcdonald, Bruce D. Chapman, Katherine Jensen, Erika Podest, Zachary D. Tessler, Theodore J. Bohn, Reiner Zimmermann

Publications and Research

The sensitivity of Earth’s wetlands to observed shifts in global precipitation and temperature patterns and their ability to produce large quantities of methane gas are key global change questions. We present a microwave satellite-based approach for mapping fractional surface water (FW) globally at 25-km resolution. The approach employs a land cover-supported, atmospherically-corrected dynamic mixture model applied to 20+ years (1992–2013) of combined, daily, passive/active microwave remote sensing data. The resulting product, known as Surface WAter Microwave Product Series (SWAMPS), shows strong microwave sensitivity to sub-grid scale open water and inundated wetlands comprising open plant canopies. SWAMPS’ FW compares favorably (R2 …

Hybrid Sol–Gel Glasses With Glass-Transition Temperatures Below Room Temperature, Andrei Jitianu, Guadalupe Gonzalez, Lisa C. Klein

Publications and Research

Melting gels are hybrid gels that have the ability to soften and flow at around 100 ° C for some combinations of mono- and di-substituted alkoxysiloxanes, where substitutions are either all aromatic or all aliphatic. In this study, melting gels were prepared using phenyltriethoxysilane (PhTES) and dimethyldiethoxysilane (DMDES), meaning both an aromatic and aliphatic substitution. Differential scanning calorimetry was performed to identify glass-transition temperatures, and thermal gravimetric analysis coupled with differential thermal analysis (TGA-DTA) was performed to measure weight loss. The glass-transition temperatures ( T g ) ranged from – 61 ° C to + 5.6 ° C, which are …

The Mathematics And Applications Behind Image Warping And Morphing, Tanvir Prince, Maria Malik, Ildefonso Salva, Ariel Mazor, Sakhr Aldaylam

Publications and Research

This research is conducted in the summer of 2015 and is possible by the support of various agency, in particular, by the grant of Prof. Angulo Nieves and the New York City Research Initiative.

The purpose of this research is to reveal the mathematics and applications of the computer animation techniques of warping and morphing. A warp is a twist or distortion in the form of an object in an image while a morph is the smooth and gradual transformation of an object in one image into the object in another image. Linear algebra makes these computer animation techniques possible; …

D-Brane Instantons As Gauge Instantons In Orientifolds Of Chiral Quiver Theories, Sebastian Franco, Ander Retolaza, Angel Uranga

Publications and Research

Systems of D3-branes at orientifold singularities can receive non-perturbative D-brane instanton corrections, inducing field theory operators in the 4d effective theory. In certain non-chiral examples, these systems have been realized as the infrared end point of a Seiberg duality cascade, in which the D-brane instanton effects arise from strong gauge theory dynamics. We present the rst UV duality cascade completion of chiral D3-brane theories, in which the D-brane instantons arise from gauge theory dynamics. Chiral examples are interesting because the instanton fermion zero mode sector is topologically protected, and therefore lead to more robust setups. As an application of our …

A Geometric Approach To Quantum State Separation, E Bagan, V Yerokhin, A Shehu, Edgar Feldman, János A. Bergou

Publications and Research

Probabilistic quantum state transformations can be characterized by the degree of state separation they provide. This, in turn, sets limits on the success rate of these transformations. We consider optimum state separation of two known pure states in the general case where the known states have arbitrary a priori probabilities. The problem is formulated from a geometric perspective and shown to be equivalent to the problem of finding tangent curves within two families of conics that represent the unitarity constraints and the objective functions to be optimized, respectively. We present the corresponding analytical solutions in various forms. In the limit …

Hohenberg-Kohn Theorems In Electrostatic And Uniform Magnetostatic Fields, Xiao-Yin Pan, Viraht Sahni

Publications and Research

The Hohenberg-Kohn (HK) theorems of bijectivity between the external scalar potential and the gauge invariant nondegenerate ground state density, and the consequent Euler variational principle for the density, are proved for arbitrary electrostatic field and the constraint of fixed electron number. The HK theorems are generalized for spinless electrons to the added presence of an external uniform magnetostatic field by introducing the new constraint of fixed canonical orbital angular momentum. Thereby, a bijective relationship between the external scalar and vector potentials, and the gauge invariant nondegenerate ground state density and physical current density, is proved. A corresponding Euler variational principle …

Evaluation Of The Snow Thermal Model (Sntherm) Through Continuous In Situ Observations Of Snow’S Physical Properties At The Crest-Safe Field Experiment, José Alberto Infante Corona, Jonathan Muñoz, Tarendra Lakhankar, Peter Romanov, Reza Khanbilvardi

Publications and Research

Snowpack properties like temperature or density are the result of a complex energy and mass balance process in the snowpack that varies temporally and spatially. The Snow Thermal Model (SNTHERM) is a 1-dimensional model, energy and mass balance-driven, that simulates these properties. This article analyzes the simulated snowpack properties using SNTHERM forced with two datasets, namely measured meteorological data at the Cooperative Remote Sensing Science and Technology-Snow Analysis and Field Experiment (CREST-SAFE) site and the National Land Data Assimilation System (NLDAS). The study area is located on the premises of Caribou Municipal Airport at Caribou (ME, USA). The model evaluation …

Detecting Broken Pointcuts Using Structural Commonality And Degree Of Interest, Raffi T. Khatchadourian, Awais Rashd, Hidehiko Masuhara, Takuya Watanabe

Publications and Research

Pointcut fragility is a well-documented problem in Aspect-Oriented Programming; changes to the base code can lead to join points incorrectly falling in or out of the scope of pointcuts. Deciding which pointcuts have broken due to base-code changes is daunting, especially in large and complex systems. We present an automated approach that recommends pointcuts that are likely to require modification due to a certain base-code change and ones that do not. Our hypothesis is that join points selected by a pointcut exhibit common structural characteristics. Patterns describing such commonalities recommend pointcuts that have potentially broken to the developer. The approach …

'At-Risk' Places: Inequaties In The Distribution Of Environmental Stressors And Prescription Rates Of Mental Health Medications In Glasgow, Scotland, Juliana A. Maantay, Andrew Maroko

Publications and Research

Using geospatial analytical methods, this study examines the association between one aspect of the built environment, namely, the concentration of vacant and derelict land (VDL), and the prevalence of mental health disorders (using the proxy variable of mental health medication prescription rates) in Glasgow, Scotland. This study builds on our previous research, which demonstrated the spatial correspondence between the locations of VDL in Glasgow and several physical health outcomes. Numerous studies of other locales have found similar correspondence between different elements of the built environment and various health outcomes. This is the first study of its kind to look at …

Supporting Teachers’ Learning About Mathematical Modeling, June L. Gastón, Barbara A. Lawrence

Publications and Research

In the United States, one of the Standards for Mathematical Practice of the Common Core Curriculum (Common Core State Standards Initiative, 2010) is Model with mathematics. This standard requires that students be taught in a manner that will enable them to ―apply the mathematics they know to solve problems arising in everyday life, society, and the workplace‖ (p. 7). However many prospective and practicing teachers acquire a pedagogical style that does not support this standard. To promote higher levels of student thinking associated with mathematical modeling, teachers must thus be taught not only what mathematical modeling is, but how it …

Cladribine Analogues Via O6-(Benzotriazolyl) Derivatives Of Guanine Nucleosides, Sakilam Satishkumar, Prasanna K. Vuram, Siva Subrahmanyam Relangi, Venkateshwarlu Gurram, Hong Zhou, Robert J. Kreitman, Michelle M. Martínez Montemayor, Lijia Yang, Muralidharan Kaliyaperumal, Somesh Sharma, Narender Pottabathini, Mahesh K. Lakshman

Publications and Research

Cladribine, 2-chloro-2′-deoxyadenosine, is a highly efficacious, clinically used nucleoside for the treatment of hairy cell leukemia. It is also being evaluated against other lymphoid malignancies and has been a molecule of interest for well over half a century. In continuation of our interest in the amide bond-activation in purine nucleosides via the use of (benzotriazol-1yl-oxy)tris(dimethylamino)phosphonium hexafluorophosphate, we have evaluated the use of O6-(benzotriazol-1-yl)-2′-deoxyguanosine as a potential precursor to cladribine and its analogues. These compounds, after appropriate deprotection, were assessed for their biological activities, and the data are presented herein. Against hairy cell leukemia (HCL), T-cell lymphoma (TCL) and chronic lymphocytic …

An Evolutionary Vaccination Game In The Modified Activity Driven Network By Considering The Closeness, Dun Han, Mei Sun

Publications and Research

In this paper, we explore an evolutionary vaccination game in the modified activity driven network by considering the closeness. We set a closeness parameter p which is used to describe the way of connection between two individuals. The simulation results show that the closeness p may have an active role in weakening both the spreading of epidemic and the vaccination. Besides, when vaccination is not allowed, the final recovered density increases with the value of the ratio of the infection rate to the recovery rate λ/μ. However, when vaccination is allowed the final density of recovered individual first increases and …

2d (0,2) Quiver Gauge Theories And D-Branes, Sebastian Franco, Dongwook Ghim, Sangmin Lee, Rak-Kyeong Seong, Daisuke Yokoyama

Publications and Research

We initiate a systematic study of 2d(0,2) quiver gauge theories on the world-volume of D1-branes probing singular toric Calabi-Yau 4-folds. We present an algorithm for efficiently calculating the classical mesonic moduli spaces of these theories, which cor-respond to the probed geometries. We also introduce a systematic procedure for constructing the gauge theories for arbitrary toric singularities by means of partial resolution, which translates to higgsing in the field theory. Finally, we introduce Brane Brick Models, a novel class of brane configurations that consist of D4-branes suspended from an NS5-brane wrap-ping a holomorphic surface, tessellating a 3-torus. Brane Brick Models are …

Bulk Equations Of Motion From Cft Correlators, Daniel N. Kabat, Gilad Lifschytz

Publications and Research

ToO (1/N) we derive, purely from CFT data, the bulk equations of motion for interacting scalar fields and for scalars coupled to gauge fields and gravity. We first uplift CFT operators to mimic local AdS fields by imposing bulk microcausality. This requires adding an infinite tower of smeared higher-dimension double-trace operators to the CFT definition of a bulk field, with coefficients that we explicitly compute. By summing the contribution of the higher-dimension operators we derive the equations of motion satisfied by these uplifted CFT operators and show that we precisely recover the expected bulk equations of motion. We exhibit the …

Can Improved Agricultural Water Use Efficiency Save India’S Groundwater?, Ram Fishman, Naresh Devineni, Swaminathan Raman

Publications and Research

Irrigated agriculture is placing increasing pressure on finite freshwater resources, especially in developing countries, where water extraction is often unregulated, un-priced and even subsidized. To shift agriculture to a more sustainable use of water without harming the food security and livelihoods of hundreds of millions of smallholders, substantial improvements of water use efficiency will be required. Here, we use detailed hydroclimatic and agricultural data to estimate the potential for the widespread adoption of efficient irrigation technologies to halt the depletion of India's groundwater resources. Even though we find substantial technical potential for reversing water table declines, we show that the …

Simulating And Animating The Spatial Dynamics Of Interacting Species Living On A Torus, Boyan Kostadinov

Publications and Research

The goal of this talk is to present a student research project in computational population biology, which aims at creating a computer simulation and animation of the spatial dynamics of interactions between two kinds of species living on a torus-shaped universe. The habitat for spatial interactions is modeled by a 2D lattice with periodic boundary conditions, which wrap the rectangular grid into a torus. The spatial interactions between the species have two components: 1. Population dynamics modeled by the classical Nicholson-Bailey two-parameter family of models for coupled interactions between species, extended to incorporate space and 2. Two-parameter migration dynamics, modeled …

Comparative Sorption Of Methylene Blue Onto Hydrophobic Clays, Alvaro D. Sponza, Natalia J. Fernandez, David Yang, Karla A. Ortiz, Abel E. Navarro

Publications and Research

Chemical modifications of clay to remove methylene blue (MB) from aqueous solutions at room temperature were compared. Natural bentonite (NC) was modified by cation exchange with hexadecyltrimethylammonium chloride (HC), bencyltriethylammonium chloride (BC), and tetramethylammonium chloride (TC) to reverse the surface polarity of the hydrophilic bentonite. The adsorption of MB was studied and fitted by the adsorption theories of Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin. Equilibrium parameters were calculated, indicating that chemical modification did not improve the adsorption, due to the electrostatic adsorption mechanism. Specific surface area was determined, reporting the following trend: NC > TC > BC > HC. Isotherms show that TC is …

Polycations Xxii. Ru(Bpy)2l2 And Ru(Phen)2l2 Systems With Cationic 4,4’-Bipyridine Ligands: Syntheses, Characteristics, And Interactions With Dna, Jasmine Hatcher, Freida Zavurov, Leslie Babukutty, Thomas Strekas, Robert Engel

Publications and Research

Earlier efforts have been concerned with the association of Ruthenium octahedral complexes with DNA. Since the positively charged ruthenium species has been found to associate with the electron rich major groove of double-stranded DNA, it was proposed the addition of cationic sites on the ligands attached to ruthenium would facilitate such association. Thus, we have synthesized several series of octahedral ruthenium complexes bearing ligands having within themselves cationic sites. These have been investigated in their interaction with calf thymus DNA using fluorescence titration analysis. The introduction of the cationic ligands has been found to exhibit enhanced association of the ruthenium …

Focus On Extreme Events And The Carbon Cycle, Chuixiang Yi, Elise Pendall, Philippe Ciais

Publications and Research

Climate physics indicates that warming climate is a likely cause of extreme weather and more frequent and intense climate events. These extreme events can disrupt terrestrial carbon dynamics dramatically by triggering ecological disturbances and potentially forcing climate–carbon feedbacks. In this paper we synthesize the findings of 26 papers that focus on collecting evidence and developing knowledge of how extreme events disturb terrestrial carbon dynamics

What You Gotta Know To Play Good In The Iterated Prisoner’S Dilemma, Ethan Akin

Publications and Research

For the iterated Prisoner’s Dilemma there exist good strategies which solve the problem when we restrict attention to the long term average payoff. When used by both players, these assure the cooperative payoff for each of them. Neither player can benefit by moving unilaterally to any other strategy, i.e., these provide Nash equilibria. In addition, if a player uses instead an alternative which decreases the opponent’s payoff below the cooperative level, then his own payoff is decreased as well. Thus, if we limit attention to the long term payoff, these strategies effectively stabilize cooperative behavior. The existence of such strategies …

The Energetic Value Of Land-Based Foods In Western Hudson Bayand Their Potential To Alleviate Energy Deficits Of Starving Adult Male Polar Bears, Linda J. Gormezano, Robert F. Rockwell

Publications and Research

Climate change is predicted to expand the ice-free season in western Hudson Bay and when it grows to 180 days, 28–48% of adult male polar bears are projected to starve unless nutritional deficits can be offset by foods consumed on land. We updated a dynamic energy budget model developed by Molnar et al. to allow influx of additional energy from novel terrestrial foods (lesser snow geese, eggs, caribou) that polar bears currently consume as part of a mixed diet while on land. We calculated the units of each prey, alone and in combination, needed to alleviate these lethal energy deficits …

Kinetic Study Of The Oxygen Reduction Reaction On Α-Ni(Oh)2 And Α-Ni(Oh)2 Supported On Graphene Oxide, Elaheh Farjami, L. Jay Deiner

Publications and Research

The kinetics of the oxygen reduction reaction on α-Ni(OH)2 and α-Ni(OH)2 supported on graphene oxide (α-Ni(OH)2/GO) were investigated using rotating disk linear sweep voltammetry in alkaline solutions of varying oxygen and hydroxyl concentrations. Over the full hydroxyl concentration range (0.05 M to 0.5M), α-Ni(OH)2/GO displayed higher activity than unsupported α-Ni(OH)2. The electron transfer numbers were 2.9 ± 0.2 for α-Ni(OH)2, 3.4 ± 0.1 for α-Ni(OH)2/GO at low [OH−], and 3.8–3.9 for α-Ni(OH)2/GO at high [OH−]. Compared to α-Ni(OH)2, α-Ni(OH)2/GO displayed higher chemical reaction rate constants and higher electron transfer rate constants. These differences suggest that the synergy between the α-Ni(OH)2 …

Time Series Analysis For Psychological Research: Examining And Forecasting Change, Andrew T. Jebb, Louis Tay, Wei Wang, Qiming Huang

Publications and Research

Psychological research has increasingly recognized the importance of integrating temporal dynamics into its theories, and innovations in longitudinal designs and analyses have allowed such theories to be formalized and tested. However, psychological researchers may be relatively unequipped to analyze such data, given its many characteristics and the general complexities involved in longitudinal modeling. The current paper introduces time series analysis to psychological research, an analytic domain that has been essential for understanding and predicting the behavior of variables across many diverse fields. First, the characteristics of time series data are discussed. Second, different time series modeling techniques are surveyed that …

Evaluation Of Alos Palsar Data For High-Resolution Mapping Of Vegetated Wetlands In Alaska, Daniel Clewley, Jane Whitcomb, Mahta Moghaddam, Kyle Macdonald, Bruce Chapman, Peter Bunting

Publications and Research

As the largest natural source of methane, wetlands play an important role in the carbon cycle. High-resolution maps of wetland type and extent are required to quantify wetland responses to climate change. Mapping northern wetlands is particularly important because of a disproportionate increase in temperatures at higher latitudes. Synthetic aperture radar data from a spaceborne platform can be used to map wetland types and dynamics over large areas. Following from earlier work by Whitcomb et al. (2009) using Japanese Earth Resources Satellite (JERS-1) data, we applied the “random forests” classification algorithm to variables from L-band ALOS PALSAR data for 2007, …

Using Python To Solve The Navier-Stokes Equations - Applications In The Preconditioned Iterative Methods, Jia Liu, Lina Wu, Xingang Fang

Publications and Research

This article describes a new numerical solver for the Navier-Stokes equations. The proposed solver is written in Python which is a newly developed language. The Python packages are built to solve the Navier-Stokes equations with existing libraries. We have created discretized coefficient matrices from systems of the Navier-Stokes equations by the finite difference method. In addition we focus on the preconditioned Krylov subspace iterative methods in the linearized systems. Numerical results of performances for the Preconditioned iterative methods are demonstrated. The comparison between Python and Matlab is discussed at the end of the paper.

Statement And Action Agenda From The Girls In Emergencies Collaborative, Omar Robles, Judith Bruce, Holly G. Atkinson, Dale Buscher, Karen Scriven, Kristin Kim Bart, Shelby French, Judithe Registre, Audrey Anderson

Publications and Research

Many adolescent girls—the poorest girls in the poorest communities—already live in an “emergency.” Humanitarian crises only amplify the call on their coping and caring capacities, while exacerbating their vulnerabilities. The frequency and intensity of emergencies, including natural disasters, conflicts, and infectious disease outbreaks such as Ebola, appear to be growing. These emergencies threaten entire communities and whole countries, often with global implications. Many become virtually permanent.