Results for "Courtney J Spoerer"

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Recurrence required to capture the dynamic computations of the human ventral visual streamMar 14 2019The visual system is an intricate network of brain regions that enables us to recognize the world around us. Despite its abundant lateral and feedback connections, human object processing is commonly viewed and studied as a feedforward process. Here, ... More
Subgradient methods for sharp weakly convex functionsMar 06 2018Subgradient methods converge linearly on a convex function that grows sharply away from its solution set. In this work, we show that the same is true for sharp functions that are only weakly convex, provided that the subgradient methods are initialized ... More
Acoustic methods for measuring bullet velocityDec 27 2008This article describes two acoustic methods to measure bullet velocity with an accuracy of 1% or better. In one method, a microphone is placed within 0.1 m of the gun muzzle and a bullet is fired at a steel target 45 m away. The bullet's flight time is ... More
Rational combinations of Betti diagrams of complete intersectionsJul 30 2015Apr 04 2017We investigate decompositions of Betti diagrams over a polynomial ring within the framework of Boij-S\"oderberg theory. That is, given a Betti diagram, we determine if it is possible to decompose it into the Betti diagrams of complete intersections. To ... More
Potential-based analyses of first-order methods for constrained and composite optimizationMar 20 2019We propose potential-based analyses for first-order algorithms applied to constrained and composite minimization problems. We first propose ``idealized'' frameworks for algorithms in the strongly and non-strongly convex cases and argue based on a potential ... More
Efficiency of minimizing compositions of convex functions and smooth mapsApr 30 2016Aug 14 2017We consider global efficiency of algorithms for minimizing a sum of a convex function and a composition of a Lipschitz convex function with a smooth map. The basic algorithm we rely on is the prox-linear method, which in each iteration solves a regularized ... More
The two-star model: exact solution in the sparse regime and condensation transitionApr 24 2015Apr 28 2015The $2$-star model is the simplest exponential random graph model that displays complex behavior, such as degeneracy and phase transition. Despite its importance, this model has been solved only in the regime of dense connectivity. In this work we solve ... More
The nonsmooth landscape of phase retrievalNov 09 2017Jan 07 2018We consider a popular nonsmooth formulation of the real phase retrieval problem. We show that under standard statistical assumptions, a simple subgradient method converges linearly when initialized within a constant relative distance of an optimal solution. ... More
Revisiting the HIP41378 system with K2 and SpitzerSep 28 2018Mar 29 2019We present new observations of the multi-planet system HIP~41378, a bright star ($V$ = 8.9, $K_s$ = 7.7) with five known transiting planets. Observations in Campaign 5 of the K2 mission showed multiple transits of two Neptune-sized bodies and single transits ... More
Revisiting the HIP41378 system with K2 and SpitzerSep 28 2018We present new observations of the multi-planet system HIP~41378, a bright star ($V$ = 8.9, $K_s$ = 7.7) with five known transiting planets. Observations in Campaign 5 of the K2 mission showed multiple transits of two Neptune-sized bodies and single transits ... More
Counting odd numbers in truncations of Pascal's triangleJul 21 2018Jul 26 2018A "truncation" of Pascal's triangle is a triangular array of numbers that satisfies the usual Pascal recurrence but with a boundary condition that declares some terminal set of numbers along each row of the array to be zero. Presented here is a family ... More
Planetary Candidates from K2 Campaign 16Mar 12 2018May 23 2018Given that Campaign 16 of the K2 mission is one of just two K2 campaigns observed so far in "forward-facing" mode, which enables immediate follow-up observations from the ground, we present a catalog of interesting targets identified through photometry ... More
Seasonal Variations in Relative Weight of Lake Trout (Salvelinus namaycush), Kokanee Salmon (Oncorhynchus nerka), Rainbow Trout (Onocorhynchus mykiss), and Brown Trout (Salmo trutta) in Blue Mesa Reservoir, ColoradoJun 15 2013Blue Mesa Reservoir is the largest body of water in Colorado and is located on the western slope of the Rocky Mountains at an elevation of 7520 feet. Blue Mesa Reservoir contains recreationally important populations of lake trout (Salvelinus namaycush), ... More
Composition Operators and EndomorphismsMar 14 2010If $b$ is an inner function, then composition with $b$ induces an endomorphism, $\beta$, of $L^\infty(\mathbb{T})$ that leaves $H^\infty(\mathbb{T})$ invariant. We investigate the structure of the endomorphisms of $B(L^2(\mathbb{T}))$ and $B(H^2(\mathbb{T}))$ ... More
A framework for torsion theory computations on elliptic threefoldsSep 27 2018We give a list of statements on the geometry of elliptic threefolds phrased only in the language of topology and homological algebra. Using only notions from topology and homological algebra, we recover existing results and prove new results on torsion ... More
Detection of the Stellar Intracluster Medium in Perseus (Abell 426)Mar 29 2017Hubble Space Telescope photometry from the ACS/WFC and WFPC2 cameras is used to detect and measure globular clusters (GCs) in the central region of the rich Perseus cluster of galaxies. A detectable population of Intragalactic GCs is found extending out ... More
60 Validated Planets from K2 Campaigns 5-8Oct 09 2018We present a uniform analysis of 155 candidates from the second year of NASA's $K2$ mission (Campaigns 5-8), yielding 60 statistically validated planets spanning a range of properties, with median values of $R_p$ = 2.5 $R_\oplus$, $P$ = 7.1 d, $T_\mathrm{eq}$ ... More
Fast Bayesian Inference for Exoplanet Discovery in Radial Velocity DataJan 27 2015Inferring the number of planets $N$ in an exoplanetary system from radial velocity (RV) data is a challenging task. Recently, it has become clear that RV data can contain periodic signals due to stellar activity, which can be difficult to distinguish ... More
Characterizing K2 Candidate Planetary Systems Orbiting Low-Mass Stars III: A High Mass & Low Envelope Fraction for the Warm Neptune K2-55bApr 14 2018Jun 28 2018K2-55b is a Neptune-sized planet orbiting a K7 dwarf with a radius of $0.715^{+0.043}_{-0.040}R_\odot$, a mass of $0.688\pm0.069 M_\odot$, and an effective temperature of $4300^{+107}_{-100}$K. Having characterized the host star using near-infrared spectra ... More
Basin bifurcations, oscillatory instability and rate-induced thresholds for AMOC in a global oceanic box modelJan 29 2019Apr 11 2019The Atlantic Meridional Overturning Circulation (AMOC) transports substantial amounts of heat into the North Atlantic sector, and hence is of very high importance in regional climate projections. The AMOC has been observed to show multi-stability across ... More
275 Candidates and 149 Validated Planets Orbiting Bright Stars in K2 Campaigns 0-10Feb 14 2018Mar 26 2018Since 2014, NASA's K2 mission has observed large portions of the ecliptic plane in search of transiting planets and has detected hundreds of planet candidates. With observations planned until at least early 2018, K2 will continue to identify more planet ... More
Thermalization, Error-Correction, and Memory Lifetime for Ising Anyon SystemsOct 31 2013Jan 26 2015We consider two-dimensional lattice models that support Ising anyonic excitations and are coupled to a thermal bath. We propose a phenomenological model for the resulting short-time dynamics that includes pair-creation, hopping, braiding, and fusion of ... More
Deep learning to generate in silico chemical property libraries and candidate molecules for small molecule identification in complex samplesMay 21 2019Comprehensive and unambiguous identification of small molecules in complex samples will revolutionize our understanding of the role of metabolites in biological systems. Existing and emerging technologies have enabled measurement of chemical properties ... More
Bayesian distances and extinctions for giants observed by Kepler and APOGEEOct 06 2014We present a first determination of distances and extinctions for individual stars in the first release of the APOKASC catalogue, built from the joint efforts of the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and the Kepler Asteroseismic ... More
Testing the Asteroseismic Mass Scale Using Metal-Poor Stars Characterized with APOGEE and KeplerMar 07 2014Fundamental stellar properties, such as mass, radius, and age, can be inferred using asteroseismology. Cool stars with convective envelopes have turbulent motions that can stochastically drive and damp pulsations. The properties of the oscillation frequency ... More
A More Accurate Fourier TransformJul 06 2015Fourier transform methods are used to analyze functions and data sets to provide frequencies, amplitudes, and phases of underlying oscillatory components. Fast Fourier transform (FFT) methods offer speed advantages over evaluation of explicit integrals ... More
Secrets of Successful Science ProjectsDec 28 2016Over the past several years, the authors have served as teachers, qualified scientists, mentors, and/or parents on dozens of science projects. These projects ranged from elementary school projects that can be completed in a weekend to high school and ... More
Impossible? Publication Quality Research with the Weakest 10% of Incoming FreshmenNov 30 2012Undergraduate research is widely regarded as a high impact practice. However, usually only the highest achieving students are rewarded with undergraduate research opportunities. This paper reports on the successful implementation of a student research ... More
High-speed measurement of rifle primer blast wavesFeb 08 2011This article describes a method and results for direct high-speed measurements of rifle primer blast waves employing a high-speed pressure transducer located at the muzzle to record the blast pressure wave produced by primer ignition. Our key findings ... More
Powder Lot Variations: A Case Study with Varget - Hodgdon ExtremeJan 27 2015Small arms propellant distributor Hodgdon claims that rifle powders in its Extreme line have small velocity variations with both temperature changes and lot number. This paper reports on the variations in average velocity of four different lots of Hodgdon ... More
Evidence for Magnetoreception in Red Drum (Sciaenops ocellatus), Black Drum (Pogonias cromis), and Sea Catfish (Ariopsis felis)Nov 30 2015Over the past few decades, magnetoreception has been discovered in several species of teleost and elasmobranch fishes by employing varied experimental methods including conditioning experiments, observations of alignment with external fields, and experiments ... More
Measuring thrust and predicting trajectory in model rocketryMar 09 2009Methods are presented for measuring thrust using common force sensors and data acquisition to construct a dynamic force plate. A spreadsheet can be used to compute trajectory by integrating the equations of motion numerically. These techniques can be ... More
Critical Pebbling Numbers of GraphsJan 17 2015We define three new pebbling parameters of a connected graph $G$, the $r$-, $g$-, and $u$-critical pebbling numbers. Together with the pebbling number, the optimal pebbling number, the number of vertices $n$ and the diameter $d$ of the graph, this yields ... More
Environmental and fishing effects on the dynamic of brown tiger prawn (Penaeus esculentus) in Moreton Bay (Australia)Jun 16 2013Dec 18 2013This analysis of the variations of brown tiger prawn (Penaeus esculentus) catch in the Moreton Bay multispecies trawl fishery estimated catchability using a delay difference model. It integrated several factors responsible for variations in catchability: ... More
Probing $Λ$CDM cosmology with the Evolutionary Map of the Universe surveyOct 15 2018Feb 18 2019The Evolutionary Map of the Universe (EMU) is an all-sky survey in radio-continuum which uses the Australian SKA Pathfinder (ASKAP). Using galaxy angular power spectrum and the integrated Sachs-Wolfe effect, we study the potential of EMU to constrain ... More
Experimental Tests of the Proportionality of Aerodynamic Drag to Air Density for Supersonic ProjectilesOct 26 2015Pure theory recognizes the dependence of supersonic drag coefficients on both Mach number and Reynolds number, which includes an implicit dependence of drag coefficient on air density. However, many modern approaches to computing trajectories for artillery ... More
Shock Tube Design for High Intensity Blast Waves for Laboratory Testing of Armor and Combat MaterielJan 30 2015Shock tubes create simulated blast waves which can be directed and measured to study blast wave effects under laboratory conditions. It is desirable to increase available peak pressure from ~1 MPa to ~5 MPa to simulate closer blast sources and facilitate ... More
Bright Opportunities for Atmospheric Characterization of Small Planets: Masses and Radii of K2-3 b, c, d and GJ3470 b from Radial Velocity Measurements and Spitzer TransitsDec 19 2018Feb 14 2019We report improved masses, radii, and densities for four planets in two bright M-dwarf systems, K2-3 and GJ3470, derived from a combination of new radial velocity and transit observations. Supplementing K2 photometry with follow-up Spitzer transit observations ... More
The Evening Tutoring Center at the United States Air Force AcademyFeb 09 2011The United States Air Force Academy (USAFA) has opened an Evening Tutoring Center to provide after-hours tutoring every evening before class days. The center focuses on first and second year courses in challenging quantitative disciplines: mathematics, ... More
Review of Magnetic Shark Deterrents: Hypothetical Mechanisms and Evidence for SelectivityNov 24 2014Several papers published since 2006 describe effects of magnetic fields on elasmobranchs and assess their utility in reducing negative interactions between sharks and humans, including bycatch reduction. Most of these repeat a single untested hypothesis ... More
A TESS Dress Rehearsal: Planetary Candidates and Variables from K2 Campaign 17Jun 08 2018We produce light curves for all ~34,000 targets observed with K2 in Campaign 17 (C17), identifying 34 planet candidates, 184 eclipsing binaries, and 222 other periodic variables. The location of the C17 field means follow-up can begin immediately now ... More
Methods for Accurate Free Flight Measurement of Drag CoefficientsMar 18 2015This paper describes experimental methods for free flight measurement of drag coefficients to an accuracy of approximately 1%. There are two main methods of determining free flight drag coefficients, or equivalent ballistic coefficients: 1) measuring ... More
A $55 Shock Tube for Simulated Blast WavesFeb 21 2015Shock tubes are commonly employed to test candidate armor materials, validate numerical models, and conduct simulated blast experiments in animal models. As DoD interests desire to field wearable sensors as blast dosimeters, shock tubes may also serve ... More
Device for Underwater Laboratory Simulation of Unconfined Blast WavesJun 08 2015Shock tubes simulate blast waves to study their effects in air under laboratory conditions; however, few experimental models exist for simulating underwater blast waves that are needed for facilitating experiments in underwater blast transmission, determining ... More
Catalog of New K2 Exoplanet Candidates from Citizen ScientistsMar 01 2019Mar 05 2019We provide 28 new planet candidates that have been vetted by citizen scientists and expert astronomers. This catalog contains 9 likely rocky candidates ($R_{pl} < 2.0R_\oplus$) and 19 gaseous candidates ($R_{pl} > 2.0R_\oplus$). Within this list we find ... More
Early Results from APOKASCSep 08 2014Asteroseismology and spectroscopy provide complementary constraints on the fundamental and chemical properties of stars. I describe the first results from APOKASC, a collaboration between the Kepler asteroseismic science consortium (KASC) and the SDSS-III ... More
Is it Possible to Accurately Identify a Shooter's Face as Illuminated by the Muzzle Flash of a 22 LR Pistol?Oct 22 2014The science of firearms muzzle flash has been dominated by three perspectives: 1) Does the muzzle flash reveal friendly positions to naked eye observers so as to draw fire from enemy combatants? 2) Can flash signatures be recognized by electronic surveillance ... More
An Acoustic Demonstration of Galileo's Law of Falling BodiesFeb 08 2011An acoustic method is presented for analyzing the time of falling motion. A ball is dropped from a measured height. The dropping device makes a distinct sound a well-determined time (roughly 14 milliseconds) after release. The ball subsequently makes ... More
Unions of arcs from Fourier partial sumsFeb 03 2010Mar 03 2010Elementary complex analysis and Hilbert space methods show that a union of at most n arcs on the circle is uniquely determined by the nth Fourier partial sum of its characteristic function. The endpoints of the arcs can be recovered from the coefficients ... More
EarthFinder: A Precise Radial Velocity Probe Mission Concept For the Detection of Earth-Mass Planets Orbiting Sun-like StarsMar 11 2018EarthFinder is a Probe Mission concept selected for study by NASA for input to the 2020 astronomy decadal survey. This study is currently active and a final white paper report is due to NASA at the end of calendar 2018. We are tasked with evaluating the ... More
On osp(2|2) conformal field theoriesNov 25 2002Mar 21 2003We study the conformal field theories corresponding to current superalgebras $osp(2|2)^{(1)}_k$ and $osp(2|2)^{(2)}_k$. We construct the free field realizations, screen currents and primary fields of these current superalgebras at general level $k$. All ... More
KELT-19Ab: A P~4.6 Day Hot Jupiter Transiting a Likely Am Star with a Distant Stellar CompanionSep 20 2017Dec 22 2017We present the discovery of the giant planet KELT-19Ab, which transits the moderately bright $(\mathrm{V} \sim 9.9)$ A8V star TYC 764-1494-1 with an orbital period of 4.61 days. We confirm the planetary nature of the companion via a combination of radial ... More
Derivation of Delay Equation Climate Models Using the Mori-Zwanzig FormalismFeb 08 2019Models incorporating delay have been frequently used to understand climate variability phenomena, but often the delay is introduced through an ad-hoc physical reasoning, such as the propagation time of waves. In this paper, the Mori-Zwanzig formalism ... More
The Maximum Likelihood Degree of Toric VarietiesMar 07 2017Nov 08 2017We study the maximum likelihood degree (ML degree) of toric varieties, known as discrete exponential models in statistics. By introducing scaling coefficients to the monomial parameterization of the toric variety, one can change the ML degree. We show ... More
Performance testing of lead free primers: blast waves, velocity variations, and environmental testingOct 23 2014Results are presented for lead free primers based on diazodinitrophenol (DDNP)compared with tests on lead styphnate based primers. First, barrel friction measurements in 5.56 mm NATO are presented. Second, shot to shot variations in blast waves are presented ... More
Terminal Performance of Lead-Free Pistol Bullets in Ballistic Gelatin Using Retarding Force Analysis from High Speed VideoApr 04 2016Due to concerns about environmental and industrial hazards of lead, a number of military, law enforcement, and wildlife management agencies are giving careful consideration to lead-free ammunition. The goal of lead-free bullets is to gain the advantages ... More
The Science Case for an Extended Spitzer MissionOct 11 2017Although the final observations of the Spitzer Warm Mission are currently scheduled for March 2019, it can continue operations through the end of the decade with no loss of photometric precision. As we will show, there is a strong science case for extending ... More
Rational combinations of Betti diagrams of complete intersectionsJul 30 2015Dec 14 2015We investigate decompositions of Betti diagrams over a polynomial ring within the framework of Boij-S\"oderberg theory. That is, given a Betti diagram, we determine if it is possible to decompose it into the Betti diagrams of complete intersections. To ... More
Gyroscopic Stability of Open Tipped Match Style Rifle BulletsJan 16 2014Oct 16 2014Earlier work has produced formulas for predicting stability of rifle bullets of near uniform density and also for plastic-tipped rifle bullets. These formulas have been shown to be accurate within 5%. However, the original Miller stability formula for ... More
Aerodynamic Drag and Gyroscopic StabilityAug 15 2013Oct 16 2014This paper describes the effects on aerodynamic drag of rifle bullets as the gyroscopic stability is lowered from 1.3 to 1.0. It is well known that a bullet can tumble for stability less than 1.0. The Sierra Loading Manuals (4th and 5th Editions) have ... More
EI VideosApr 11 2012The Quantitative Reasoning Center (QRC) at USAFA has the institution's primary responsibility for offering after hours extra instruction (EI) in core technical disciplines (mathematics, chemistry, physics, and engineering mechanics). Demand has been tremendous, ... More
Illuminating Fourier Series with AudacityNov 20 2012This paper briefly describes some simple techniques for illuminating Fourier series and Fourier analysis with the Audacity sound recording program. These techniques are easily applied in the classroom and help students move beyond formula roulette in ... More
Studying the Internal Ballistics of a Combustion Driven Potato Cannon using High-speed VideoMay 04 2013A potato cannon was designed to accommodate several different experimental propellants and have a transparent barrel so the movement of the projectile could be recorded on high-speed video (at 2000 frames per second). Both combustion chamber and barrel ... More
Why Cheating is WrongFeb 08 2011Mathieu Bouville's "Why is cheating wrong?" (Studies in Philosophy and Education, 29(1), 67-76, 2010) misses the mark by failing to consider the longer term consequences of cheating on student character development and longer term societal consequences ... More
Learning from Videos with Deep Convolutional LSTM NetworksApr 09 2019This paper explores the use of convolution LSTMs to simultaneously learn spatial- and temporal-information in videos. A deep network of convolutional LSTMs allows the model to access the entire range of temporal information at all spatial scales of the ... More
Elements of $C^*$-algebras Attaining Their Norm in a Finite-Dimensional RepresentationJul 06 2017We characterize the class of RFD $C^*$-algebras as those containing a dense subset of elements that attain their norm under a finite-dimensional representation. We show further that this subset is the whole space precisely when every irreducible representation ... More
Lifting endomorphisms to automorphismsMar 04 2007Mar 13 2007Normal endomorphisms of von Neumann algebras need not be extendable to automorphisms of a larger von Neumann algebra, but they always have asymptotic lifts. We describe the structure of endomorphisms and their asymptotic lifts in some detail, and apply ... More
Accurate Measurements of Free Flight Drag Coefficients with Amateur Doppler RadarAug 23 2016In earlier papers, techniques have been described using optical chronographs to determine free flight drag coefficients with an accuracy of 1-2%, accomplished by measuring near and far velocities of projectiles in flight over a known distance. Until recently, ... More
Comparing Terminal Performance of .357 SIG and 9mm Bullets in Ballistic Gelatin Using Retarding Force Analysis from High Speed VideoAug 21 2015High-speed video has emerged as an valuable tool for quantifying bullet performance in ballistic gelatin. This paper presents the results of testing four .357 SIG bullets using high-speed video of bullet impacts in ballistic gelatin to determine retarding ... More
Photometric Trends in the Visible Solar Continuum and Their Sensitivity to the Center-to-Limb ProfileFeb 23 2015Jun 25 2015Solar irradiance variations over solar rotational time-scales are largely determined by the passage of magnetic structures across the visible solar disk. Variations on solar cycle time scales are thought to be similarly due to changes in surface magnetism ... More
Echo-based measurement of the speed of soundFeb 14 2011The speed of sound in air can be measured by popping a balloon next to a microphone a measured distance away from a large flat wall, digitizing the sound waveform, and measuring the time between the sound of popping and return of the echo to the microphone. ... More
Small-Network Approximations for Geometrically Frustrated Ising SystemsJul 14 2011The study of frustrated spin systems often requires time-consuming numerical simulations. As the simplest approach, the classical Ising model is often used to investigate the thermodynamic behavior of such systems. Exploiting the small correlation lengths ... More
The universal C*-algebra of a contractionNov 09 2018May 03 2019We say that a contractive Hilbert space operator is universal if there is a natural surjection from its generated C*-algebra to the C*-algebra generated by any other contraction. A universal contraction may be irreducible or a direct sum of (even nilpotent) ... More
A Tentative Role for FOXP2 in the Evolution of Dual Processing Modes and Generative AbilitiesAug 11 2014It has been suggested that the origins of cognitive modernity in the Middle/Upper Paleolithic following the appearance of anatomically modern humans was due to the onset of dual processing or contextual focus (CF), the ability to shift between different ... More
An accelerated algorithm for minimizing convex compositionsApr 30 2016We describe a new proximal algorithm for minimizing compositions of finite-valued convex functions with smooth mappings. When applied to convex optimization problems having an additive composite form, the algorithm reduces to FISTA. The method both realizes ... More
Measuring Bullet Velocity with a PC SoundcardJan 14 2006This article describes a simple method for using a PC soundcard to accurately measure bullet velocity. The method involves placing the microphone within a foot of the muzzle and firing at a steel target between 50 and 100 yards away. The time of flight ... More
Is Carbon Cycling Keeping Pace with Increases in Atmospheric Carbon Dioxide?Dec 20 2018Carbon dioxide (CO2) increase has been well documented, and global net primary production is of importance to a variety of ecological topics. Since CO2 increases primary production in laboratory experiments, the global effects of increasing CO2 on global ... More
Free products with amalgamation over central C*-subalgebrasSep 24 2018Dec 14 2018Let A and B be C*-algebras whose quotients are all RFD, and let C be a central C*-subalgebra in both A and B. We prove that the full amalgamated free product of A and B over C is then RFD. This generalizes Korchagin's result that amalgamated free products ... More
Some notes on the universal C*-algebra of a contractionNov 09 2018Dec 06 2018We say that a contractive Hilbert space operator is universal if there is a natural surjection from its generated C*-algebra to the C*-algebra generated by any other contraction. A universal contraction may be irreducible or a direct sum of (even nilpotent) ... More
A mini-max problem for self-adjoint Toeplitz matricesSep 14 2010Jan 18 2011We study a minimum problem and associated maximum problem for finite, complex, self-adjoint Toeplitz matrices. If $A$ is such a matrix, of size $(N+1)$-by-$(N+1)$, we identify $A$ with the operator it represents on $P_N$, the space of complex polynomials ... More
Generalized network structures: The configuration model and the canonical ensemble of simplicial complexesFeb 12 2016Jun 06 2016Simplicial complexes are generalized network structures able to encode interactions occurring between more than two nodes. Simplicial complexes describe a large variety of complex interacting systems ranging from brain networks, to social and collaboration ... More
Harmonic equiangular tight frames comprised of regular simplicesMar 21 2019An equiangular tight frame (ETF) is a sequence of unit-norm vectors in a Euclidean space whose coherence achieves equality in the Welch bound, and thus yields an optimal packing in a projective space. A regular simplex is a simple type of ETF in which ... More
A spectacular giant arc in the massive cluster lens MACSJ1206.2-0847Jan 14 2009We discuss the X-ray and optical properties of the massive galaxy cluster MACSJ1206.2-0847 (z=0.4385), discovered in the Massive Cluster Survey (MACS). Our Chandra observation of the system yields a total X-ray luminosity of 2.4 x 10^45 erg/s (0.1-2.4 ... More
Bullet Retarding Forces in Ballistic Gelatin by Analysis of High Speed VideoMay 22 2013Though three distinct wounding mechanisms (permanent cavity, temporary cavity, and ballistic pressure wave) are described in the wound ballistics literature, they all have their physical origin in the retarding force between bullet and tissue as the bullet ... More
The KELT Follow-Up Network and Transit False Positive Catalog: Pre-vetted False Positives for TESSMar 05 2018Sep 19 2018The Kilodegree Extremely Little Telescope (KELT) project has been conducting a photometric survey for transiting planets orbiting bright stars for over ten years. The KELT images have a pixel scale of ~23"/pixel---very similar to that of NASA's Transiting ... More
The L 98-59 System: Three Transiting, Terrestrial-Sized Planets Orbiting a Nearby M-dwarfMar 19 2019We report the Transiting Exoplanet Survey Satellite (TESS) discovery of three terrestrial-sized planets transiting L 98-59 (TOI-175, TIC 307210830) -- a bright M dwarf at a distance of 10.6 pc. Using the Gaia-measured distance and broad-band photometry ... More
Non-Gaussianity in Two-Field InflationNov 30 2010Dec 14 2010We derive semi-analytic formulae for the local bispectrum and trispectrum in general two-field inflation and provide a simple geometric recipe for building observationally allowed models with observable non-Gaussianity. We use the \delta N formalism and ... More
High-speed measurement of firearm primer blast wavesMar 13 2012This article describes a method and results for direct high-speed measurements of firearm primer blast waves employing a high-speed pressure transducer located at the muzzle to record the blast pressure wave produced by primer ignition. Key findings are: ... More
The Need for Laboratory Measurements and Ab Initio Studies to Aid Understanding of Exoplanetary AtmospheresMay 16 2019We are now on a clear trajectory for improvements in exoplanet observations that will revolutionize our ability to characterize their atmospheric structure, composition, and circulation, from gas giants to rocky planets. However, exoplanet atmospheric ... More
Demonstrating an Improved Length-weight Model in Largemouth Bass, Chain Pickerel, Yellow Perch, Black Crappie, and Brown Bullhead in Stilwell Reservoir, West Point, New YorkJul 02 2011The traditional power law model, W(L) = aL^b, is widely applied to describe weight (W) vs. length (L) in fish. The model, W(L) = (L/L1)^b, is proposed as an improvement. The Levenberg-Marquardt non-linear least squares technique is used to determine the ... More
Plump Cutthroat Trout and Thin Rainbow Trout in a Lentic EcosystemOct 17 2012Background: Much has been written about introduced rainbow trout (Oncorhynchus mykiss) interbreeding and outcompeting cutthroat trout (Oncorhynchus clarkii). However, the specific mechanisms by which rainbow trout and their hybrids outcompete cutthroat ... More
Dense Power-law Networks and Simplicial ComplexesFeb 05 2018There is increasing evidence that dense networks occur in on-line social networks, recommendation networks and in the brain. In addition to being dense, these networks are often also scale-free, i.e. their degree distributions follow $P(k)\propto k^{-\gamma}$ ... More
The Occurrence of Potentially Habitable Planets Orbiting M Dwarfs Estimated from the Full Kepler Dataset and an Empirical Measurement of the Detection SensitivityJan 07 2015May 26 2015We present an improved estimate of the occurrence rate of small planets orbiting small stars by searching the full four-year Kepler data set for transiting planets using our own planet detection pipeline and conducting transit injection and recovery simulations ... More
The Occurrence Rate of Small Planets around Small StarsFeb 07 2013Feb 22 2013We use the optical and near-infrared photometry from the Kepler Input Catalog to provide improved estimates of the stellar characteristics of the smallest stars in the Kepler target list. We find 3897 dwarfs with temperatures below 4000K, including 64 ... More
Testing Multi-Field Inflation: A Geometric ApproachNov 03 2011Nov 22 2012We develop an approach for linking the power spectra, bispectrum, and trispectrum to the geometric and kinematical features of multifield inflationary Lagrangians. Our geometric approach can also be useful in determining when a complicated multifield ... More
Testing Two-Field InflationMay 21 2010Oct 29 2010We derive semi-analytic formulae for the power spectra of two-field inflation assuming an arbitrary potential and non-canonical kinetic terms, and we use them both to build phenomenological intuition and to constrain classes of two-field models using ... More
Galaxy Structure in the Ultraviolet: The Dependence of Morphological Parameters on Rest-Frame WavelengthAug 01 2018Evolutionary studies that compare galaxy structure as a function of redshift are complicated by the fact that any particular galaxy's appearance depends in part on the rest-frame wavelength of the observation. This leads to the necessity for a "morphological ... More
Phenomenological forecasting of disease incidence using heteroskedastic Gaussian processes: a dengue case studyFeb 01 2017Aug 01 2017In 2015 the US federal government sponsored a dengue forecasting competition using historical case data from Iquitos, Peru and San Juan, Puerto Rico. Competitors were evaluated on several aspects of out-of-sample forecasts including the targets of peak ... More
Size Gap for Zero Temperature Black Holes in Semiclassical GravityJun 16 1998We show that a gap exists in the allowed sizes of all zero temperature static spherically symmetric black holes in semiclassical gravity when only conformally invariant fields are present. The result holds for both charged and uncharged black holes. By ... More
There's No Comparison: Reference-less Evaluation Metrics in Grammatical Error CorrectionOct 07 2016Current methods for automatically evaluating grammatical error correction (GEC) systems rely on gold-standard references. However, these methods suffer from penalizing grammatical edits that are correct but not in the gold standard. We show that reference-less ... More