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Quantum Mechanics with a Momentum-Space Artificial Magnetic FieldMar 24 2014Nov 19 2014The Berry curvature is a geometrical property of an energy band which acts as a momentum space magnetic field in the effective Hamiltonian describing single-particle quantum dynamics. We show how this perspective may be exploited to study systems directly ... More

Momentum-space Harper-Hofstadter modelNov 05 2014Aug 14 2015We show how the weakly trapped Harper-Hofstadter model can be mapped onto a Harper-Hofstadter model in momentum space. In this momentum-space model, the band dispersion plays the role of the periodic potential, the Berry curvature plays the role of an ... More

Effects of Berry Curvature on the Collective Modes of Ultracold GasesJun 20 2013Nov 28 2013Topological energy bands have important geometrical properties described by the Berry curvature. We show that the Berry curvature changes the hydrodynamic equations of motion for a trapped Bose-Einstein condensate, and causes significant modifications ... More

Experimental Measurement of the Berry Curvature from Anomalous TransportSep 29 2016Geometrical properties of energy bands underlie fascinating phenomena in a wide-range of systems, including solid-state materials, ultracold gases and photonics. Most famously, local geometrical characteristics like the Berry curvature can be related ... More

Spin-orbit coupling in a hexagonal ring of pendulaSep 30 2016We consider the mechanical motion of a system of six macroscopic pendula which are connected with springs and arranged in a hexagonal geometry. When the springs are pre-tensioned, the coupling between neighbouring pendula along the longitudinal (L) and ... More

Generating Music from LiteratureMar 10 2014We present a system, TransProse, that automatically generates musical pieces from text. TransProse uses known relations between elements of music such as tempo and scale, and the emotions they evoke. Further, it uses a novel mechanism to determine sequences ... More

The subset-matched Jaccard index for evaluation of Segmentation for Plant ImagesNov 21 2016We describe a new measure for the evaluation of region level segmentation of objects, as applied to evaluating the accuracy of leaf-level segmentation of plant images. The proposed approach enforces the rule that a region (e.g. a leaf) in either the image ... More

Ionized and molecular gas kinematics in a z=1.4 star-forming galaxyFeb 06 2018We present deep observations of a $z=1.4$ massive, star-forming galaxy in molecular and ionized gas at comparable spatial resolution (CO 3-2, NOEMA; H$\alpha$, LBT). The kinematic tracers agree well, indicating that both gas phases are subject to the ... More

Parameter estimation on gravitational waves from neutron-star binaries with spinning componentsAug 21 2015Mar 10 2016Inspiraling binary neutron stars are expected to be one of the most significant sources of gravitational-wave signals for the new generation of advanced ground-based detectors. We investigate how well we could hope to measure properties of these binaries ... More

Quantum Hall effect in momentum spaceFeb 24 2016May 04 2016We theoretically discuss a momentum-space analog of the quantum Hall effect, which could be observed in topologically nontrivial lattice models subject to an external harmonic trapping potential. In our proposal, the Niu-Thouless-Wu formulation of the ... More

Synthetic Dimensions for Cold Atoms from Shaking a Harmonic TrapMay 30 2016Jun 23 2016We introduce a simple scheme to implement synthetic dimensions and gauge fields in ultracold atomic gases, which only requires two basic and ubiquitous ingredients: the harmonic trap, which confines the atoms, combined with a periodic shaking. In our ... More

Parameter estimation for binary neutron-star coalescences with realistic noise during the Advanced LIGO eraNov 25 2014May 12 2015Advanced ground-based gravitational-wave (GW) detectors begin operation imminently. Their intended goal is not only to make the first direct detection of GWs, but also to make inferences about the source systems. Binary neutron-star mergers are among ... More

Millimeter mapping at z~1: dust-obscured bulge building and disk growthJan 08 2018A randomly chosen star in today's Universe is most likely to live in a galaxy with a stellar mass between that of the Milky Way and Andromeda. Yet it remains uncertain how the structural evolution of these bulge-disk systems proceeded. Most of the unobscured ... More

A Boolean Gene Regulatory Model of heterosis and speciationSep 15 2013Mar 23 2015Modelling genetic phenomena affecting biological traits is important for the development of agriculture as it allows breeders to predict the potential of breeding for certain traits. One such phenomenon is heterosis or hybrid vigor: crossing individuals ... More

Transferable neural networks for enhanced sampling of protein dynamicsJan 02 2018Variational auto-encoder frameworks have demonstrated success in reducing complex nonlinear dynamics in molecular simulation to a single non-linear embedding. In this work, we illustrate how this non-linear latent embedding can be used as a collective ... More

Coefficients of McKay-Thompson series and distributions of the moonshine moduleAug 15 2015Jan 03 2016In a recent paper, Duncan, Griffin and Ono provide exact formulas for the coefficients of McKay-Thompson series and use them to find asymptotic expressions for the distribution of irreducible representations in the moonshine module $V^\natural = \bigoplus_n ... More

Semidualizing DG Modules over Tensor ProductsNov 25 2014We study the existence of nontrivial semidualizing DG modules over tensor products of DG algebras over a field. In particular, this gives a lower bound on the number of semidualizing DG modules over the tensor product.

Black hole collisions from Brill-Lindquist initial data: predictions of perturbation theorySep 09 1995The Misner initial value solution for two momentarily stationary black holes has been the focus of much numerical study. We report here analytic results for an astrophysically similar initial solution, that of Brill and Lindquist (BL). Results are given ... More

Applying black hole perturbation theory to numerically generated spacetimesAug 29 1995Nonspherical perturbation theory has been necessary to understand the meaning of radiation in spacetimes generated through fully nonlinear numerical relativity. Recently, perturbation techniques have been found to be successful for the time evolution ... More

Spitzer, Gaia, and the Potential of the Milky WayAug 12 2013Nov 11 2013Near-future data from ESA's Gaia mission will provide precise, full phase-space information for hundreds of millions of stars out to heliocentric distances of ~10 kpc. This "horizon" for full phase-space measurements is imposed by the Gaia parallax errors ... More

Tidally-Distorted, Iron-Enhanced Exoplanets Closely Orbiting Their StarsJan 30 2019The origin of Mercury's enhanced iron content is a matter of ongoing debate. The characterization of rocky exoplanets promises to provide new, independent insights on this topic by constraining the occurrence rate and physical and orbital properties of ... More

How to directly observe Landau levels in driven-dissipative strained honeycomb latticesApr 15 2015Sep 24 2015We study the driven-dissipative steady-state of a coherently-driven Bose field in a honeycomb lattice geometry. In the presence of a suitable spatial modulation of the hopping amplitudes, a valley-dependent artificial magnetic field appears and the low-energy ... More

Artificial Magnetic Fields in Momentum Space in Spin-Orbit Coupled SystemsDec 11 2014Apr 01 2015The Berry curvature is a geometrical property of an energy band which can act as a momentum space magnetic field in the effective Hamiltonian of a wide range of systems. We apply the effective Hamiltonian to a spin-1/2 particle in two dimensions with ... More

Floquet topological system based on frequency-modulated classical coupled harmonic oscillatorsOct 15 2015Feb 03 2016We theoretically propose how to observe topological effects in a generic classical system of coupled harmonic oscillators, such as classical pendula or lumped-element electric circuits, whose oscillation frequency is modulated fast in time. Making use ... More

Momentum-space Landau levels in driven-dissipative cavity arraysOct 11 2015Jan 21 2016We theoretically study the driven-dissipative Harper-Hofstadter model on a 2D square lattice in the presence of a weak harmonic trap. Without pumping and loss, the eigenstates of this system can be understood, in certain limits, as momentum-space toroidal ... More

Probing the QCD Critical Point with Relativistic Heavy-Ion CollisionsFeb 01 2012We utilize an event-by-event relativistic hydrodynamic calculation performed at a number of different incident beam energies to investigate the creation of hot and dense QCD matter near the critical point. Using state-of-the-art analysis and visualization ... More

Gating of neural error signals during motor learningMar 11 2014Mar 17 2014Cerebellar climbing fiber activity encodes performance errors during many motor learning tasks, but the role of these error signals in learning has been controversial. We compared two motor learning paradigms that elicited equally robust putative error ... More

Benchmarking a Non-Equilibrium Approach to Photon Emission in Relativistic Heavy-Ion CollisionsFeb 20 2019In this work, the production of photons through binary scattering processes is investigated for equilibrated hadronic systems. More precisely, a non-equilibrium hadronic transport approach to describe relativistic heavy-ion collisions is benchmarked with ... More

A high resolution study of complex organic molecules in hot coresJul 07 2014We present the results of a line identification analysis using data from the IRAM Plateau de Bure Inferferometer, focusing on six massive star-forming hot cores: G31.41+0.31, G29.96-0.02, G19.61-0.23, G10.62-0.38, G24.78+0.08A1 and G24.78+0.08A2. We identify ... More

Why stellar feedback promotes disc formation in simulated galaxiesMar 24 2014Jul 04 2014We study how feedback influences baryon infall onto galaxies using cosmological, zoom-in simulations of haloes with present mass $M_{vir}=6.9\times10^{11} M_{\odot}$ to $1.7\times10^{12} M_{\odot}$. Starting at z=4 from identical initial conditions, implementations ... More

Modelling of c-C2H4O formation on grain surfacesSep 12 2012Despite its potential reactivity due to ring strain, ethylene oxide (c-C2H4O) is a complex molecule that seems to be stable under the physical conditions of an interstellar dense core; indeed it has been detected towards several high-mass star forming ... More

The density variance -- Mach number relation in supersonic, isothermal turbulenceOct 18 2010Dec 13 2010We examine the relation between the density variance and the mean-square Mach number in supersonic, isothermal turbulence, assumed in several recent analytic models of the star formation process. From a series of calculations of supersonic, hydrodynamic ... More

Magnetic field evolution in tidal disruption eventsNov 29 2016When a star gets tidally disrupted by a supermassive black hole, its magnetic field is expected to be transmitted to the debris. In this paper, we study this process via smoothed particle magnetohydrodynamical simulations of the disruption and early debris ... More

Deviations of the Energy-Momentum Tensor from Equilibrium in the Initial State for Hydrodynamics from Transport ApproachesAug 18 2015Many hybrid models of heavy ion collisions construct the initial state for hydrodynamics from transport models. Hydrodynamics requires that the energy-momentum tensor $T^{\mu\nu}$ and four-currents $j^{\mu}$ do not deviate considerably from the equilibrium ... More

Collision Energy Evolution of Elliptic and Triangular Flow in a Hybrid ModelJun 01 2013While the existence of a strongly interacting state of matter, known as 'quark-gluon plasma' (QGP), has been established in heavy ion collision experiments in the past decade, the task remains to map out the transition from the hadronic matter to the ... More

Tropical Real Hurwitz numbersDec 13 2014Aug 25 2015In this paper, we define tropical analogues of real Hurwitz numbers, i.e. numbers of covers of surfaces with compatible involutions satisfying prescribed ramification properties. We prove a correspondence theorem stating the equality of the tropical numbers ... More

Intersecting Psi-classes on tropical M_{0,n}Sep 25 2007Jul 01 2009We apply the tropical intersection theory developed by L. Allermann and J. Rau to compute intersection products of tropical Psi-classes on the moduli space of rational tropical curves. We show that in the case of zero-dimensional (stable) intersections, ... More

The Velocity Distribution Function of Galaxy Clusters as a Cosmological ProbeFeb 04 2016Oct 20 2016We present a new approach for quantifying the abundance of galaxy clusters and constraining cosmological parameters using dynamical measurements. In the standard method, galaxy line-of-sight (LOS) velocities, $v$, or velocity dispersions are used to infer ... More

Using simplicial volume to count multi-tangent trajectories of traversing vector fieldsMar 09 2015For a non-vanishing gradient-like vector field on a compact manifold $X^{n+1}$ with boundary, a discrete set of trajectories may be tangent to the boundary with reduced multiplicity $n$, which is the maximum possible. (Among them are trajectories that ... More

Length 3 Edge-Disjoint Paths and Partial OrientationJan 31 2012In 2003, it was claimed that the following problem was solvable in polynomial time: do there exist k edge-disjoint paths of length exactly 3 between vertices s and t in a given graph? The proof was flawed, and we show that this problem is NP-hard even ... More

On Unbounded Delays in Asynchronous Parallel Fixed-Point AlgorithmsSep 15 2016The need for scalable numerical solutions has motivated the development of asynchronous parallel algorithms, where a set of nodes run in parallel with little or no synchronization, thus computing with delayed information. This paper studies the convergence ... More

Initial State Fluctuations and Final State Correlations in Relativistic Heavy-Ion CollisionsDec 19 2013Jun 02 2014We review the phenomenology and theory of bulk observables in ultra-relativistic heavy-ion collisions, focussing on recent developments involving event-by-event fluctuations in the initial stages of a heavy ion collision, and how they manifest in observed ... More

On the Possibility of Event Shape Selection in Relativistic Heavy Ion CollisionsMay 13 2013Nov 12 2013We investigate the possibility of selecting heavy ion collision events with certain features in the initial state ("event engineering"). Anisotropic flow measurements in heavy ion reactions have confirmed the almost ideal fluid dynamical behaviour of ... More

Higher order corksFeb 07 2019It is shown that any finite list of smooth, closed, simply-connected 4-manifolds that are homeomorphic to a given one X can be obtained by removing a single compact contractible submanifold (or cork) from X, and then regluing it by powers of a boundary ... More

Art gallery problem with rook and queen visionOct 25 2018Nov 20 2018How many chess rooks or queens does it take to guard all the squares of a given polyomino, the union of square tiles from a square grid? This question is a version of the art gallery problem in which the guards can "see" whichever squares the rook or ... More

A conditional strong large deviation result and a functional central limit theorem for the rate functionNov 21 2014Dec 04 2014We study the large deviation behaviour of $S_n=\sum_{j=1}^n W_jZ_j$, where $(W_j)_{j \in \mathbb N}$ and $(Z_j)_{j \in \mathbb N}$ are sequences of real-valued, independent and identically distributed random variables satisfying certain moment conditions, ... More

Congruence properties of Taylor coefficients of modular formsJun 11 2014In their work, Serre and Swinnerton-Dyer study the congruence properties of the Fourier coefficients of modular forms. We examine similar congruence properties, but for the coefficients of a modified Taylor expansion about a CM point $\tau$. These coefficients ... More

Discrete Morse Theory for Computing Zigzag PersistenceJul 13 2018We introduce a theoretical and computational framework to use discrete Morse theory as an efficient preprocessing in order to compute zigzag persistent homology. From a zigzag filtration of complexes $(K_i)$, we introduce a {\em zigzag Morse filtration} ... More

The space of tropically collinear points is shellableNov 06 2007Jul 13 2009The space T_{d,n} of n tropically collinear points in a fixed tropical projective space TP^{d-1} is equivalent to the tropicalization of the determinantal variety of matrices of rank at most 2, which consists of real d x n matrices of tropical or Kapranov ... More

IRS Spectra of Debris Disks in the Scorpius-Centaurus OB AssociationJun 17 2015Jul 22 2015We analyze Spitzer IRS spectra of 110 B-, A-, F-, and G-type stars with optically thin infrared excess in the Scorpius-Centaurus (ScoCen) OB association. The age of these stars ranges from 11-17 Myr. We fit the infrared excesses observed in these sources ... More

High temperature condensate clouds in super-hot Jupiter atmospheresOct 11 2016Deciphering the role of clouds is central to our understanding of exoplanet atmospheres, as they have a direct impact on the temperature and pressure structure, and observational properties of the planet. Super-hot Jupiters occupy a temperature regime ... More

Using APOGEE Wide Binaries to Test Chemical Tagging with Dwarf StarsNov 29 2018Stars of a common origin are thought to have similar, if not nearly identical, chemistry. Chemical tagging seeks to exploit this fact to identify Milky Way subpopulations through their unique chemical fingerprints. In this work, we compare the chemical ... More

Conforming nanoparticle sheets to surfaces with Gaussian curvatureAug 10 2018Nanoparticle monolayer sheets are ultrathin inorganic-organic hybrid materials that combine highly controllable optical and electrical properties with mechanical flexibility and remarkable strength. Like other thin sheets, their low bending rigidity allows ... More

Four-Dimensional Quantum Hall Effect with Ultracold AtomsMay 17 2015Jan 29 2016We propose a realistic scheme to detect the 4D quantum Hall effect using ultracold atoms. Based on contemporary technology, motion along a synthetic fourth dimension can be accomplished through controlled transitions between internal states of atoms arranged ... More

Locality, Independence and the Pro-Liberty BellFeb 28 1996Construed as an argument against hidden variable theories, Bell's Theorem assumes that hidden variables would be independent of future measurement settings. This Independence Assumption (IA) is rarely questioned. Bell considered relaxing it to avoid non-locality, ... More

Toy Models for RetrocausalityFeb 21 2008A number of writers have been attracted to the idea that some of the peculiarities of quantum theory might be manifestations of 'backward' or 'retro' causality, underlying the quantum description. This idea has been explored in the literature in two main ... More

Smoothed Particle HydrodynamicsJul 20 2005Smoothed Particle Hydrodynamics (SPH) is a unique numerical method widely used for astrophysical problems since it involves no spatial grid. Rather, fluid quantities are carried by a set of Lagrangian `particles' which move with the flow, meaning that ... More

Synthetic dimensions in integrated photonics: From optical isolation to 4D quantum Hall physicsOct 13 2015Apr 23 2016Recent technological advances in integrated photonics have spurred on the study of topological phenomena in engineered bosonic systems. Indeed, the controllability of silicon ring-resonator arrays has opened up new perspectives for building lattices for ... More

Decisions, Decisions, Decisions: Can Savage Salvage Everettian Probability?Feb 11 2008Critics object that the Everett view cannot make sense of quantum probabilities, in one or both of two ways: either it cannot make sense of probability at all, or it cannot explain why probability should be governed by the Born rule. David Deutsch has ... More

On the ranks of elliptic curves with isogeniesNov 04 2016In recent years, the question of whether the ranks of elliptic curves defined over $\mathbb{Q}$ are unbounded has garnered much attention. One can create refined versions of this question by restricting one's attention to elliptic curves over $\mathbb{Q}$ ... More

Reconstruction from $k$-decks for graphs with maximum degree 2Sep 01 2016The $k$-deck of a graph is its multiset of induced subgraphs on $k$ vertices. We prove that $n$-vertex graphs with maximum degree $2$ have the same $k$-decks if each cycle has at least $k+1$ vertices, each path component has at least $k-1$ vertices, and ... More

Tropical geometry of genus two curvesJan 01 2018Oct 23 2018We exploit three classical characterizations of smooth genus two curves to study their tropical and analytic counterparts. First, we provide a combinatorial rule to determine the dual graph of each algebraic curve and the metric structure on the associated ... More

Survival of the impactor during hypervelocity collisions I: An analogue for low porosity targetsDec 10 2015Recent observations of asteroidal surfaces indicate the presence of materials that do not match the bulk lithology of the body. A possible explanation for the presence of these exogenous materials is that they are products of inter-asteroid impacts in ... More

Experimental Estimation of Number of Clusters Based on Cluster QualityMar 10 2015Text Clustering is a text mining technique which divides the given set of text documents into significant clusters. It is used for organizing a huge number of text documents into a well-organized form. In the majority of the clustering algorithms, the ... More

Co-moving stars in Gaia DR1: An abundance of very wide separation co-moving pairsDec 07 2016The primary sample of the Gaia Data Release 1 is the Tycho-Gaia Astrometric Solution (TGAS): $\approx$ 2 million Tycho-2 sources with improved parallaxes and proper motions relative to the initial catalog. This increased astrometric precision presents ... More

Quenched binary Bose-Einstein condensates: spin domain formation and coarseningNov 13 2012Apr 18 2013We explore the time evolution of quasi-1D two component Bose-Einstein condensates (BEC's) following a quench from one component BEC's with a ${\rm U}(1)$ order parameter into two component condensates with a ${\rm U}(1)\shorttimes{\rm Z}_2$ order parameter. ... More

Hard X-Ray Constraints on Small-Scale Coronal Heating EventsAug 08 2018Much evidence suggests that the solar corona is heated impulsively, meaning that nanoflares may be ubiquitous in quiet and active regions (ARs). Hard X-ray (HXR) observations with unprecedented sensitivity $>$3~keV are now enabled by focusing instruments. ... More

The morphology of the Milky Way - I. Reconstructing CO maps from simulations in fixed potentialsJun 16 2014We present an investigation into the morphological features of the Milky Way. We use smoothed particle hydrodynamics (SPH) to simulate the interstellar medium (ISM) in the Milky Way under the effect of a number of different gravitational potentials representing ... More

A Disk Origin for the Monoceros Ring and A13 Stellar OverdensitiesJan 03 2018The Monoceros Ring (also known as the Galactic Anticenter Stellar Structure) and A13 are stellar overdensities at estimated heliocentric distances of $d \sim 11$ kpc and 15 kpc observed at low Galactic latitudes towards the anticenter of our Galaxy. While ... More

Gallium Nitride Photodetector Measurements of UV Emission from a Gaseous CH4/O2 Hybrid Rocket Igniter PlumeFeb 07 2019Owing to its wide (3.4 eV) and direct-tunable band gap, gallium nitride (GaN) is an excellent material platform for UV photodetectors. GaN is also stable in radiation-rich and high-temperature environments, which makes photodetectors fabricated using ... More

Optimizing performance per watt on GPUs in High Performance Computing: temperature, frequency and voltage effectsJul 30 2014Oct 20 2015The magnitude of the real-time digital signal processing challenge attached to large radio astronomical antenna arrays motivates use of high performance computing (HPC) systems. The need for high power efficiency (performance per watt) at remote observatory ... More

The Joker: A custom Monte Carlo sampler for binary-star and exoplanet radial velocity dataOct 24 2016Given sparse or low-quality radial-velocity measurements of a star, there are often many qualitatively different stellar or exoplanet companion orbit models that are consistent with the data. The consequent multimodality of the likelihood function leads ... More

HHCART: An Oblique Decision TreeApr 14 2015Decision trees are a popular technique in statistical data classification. They recursively partition the feature space into disjoint sub-regions until each sub-region becomes homogeneous with respect to a particular class. The basic Classification and ... More

Tidal Stream Morphology as an Indicator of Dark Matter Halo Geometry: the Case of Palomar 5Oct 13 2014Mar 31 2016This paper presents an example where the morphology of a single stellar stream can be used to rule out a specific galactic potential form without the need for velocity information. We investigate the globular cluster Palomar5 (Pal 5), which is tidally ... More

Path-dependent initialization of a single quantum dot exciton spin in a nano-photonic waveguideSep 02 2016We demonstrate a scheme for in-plane initialization and readout of a single exciton spin in an InGaAs quantum dot (QD) coupled to a GaAs nanobeam waveguide. The chiral coupling of the QD and the optical mode of the nanobeam enables spin initialization ... More

Initial state fluctuations and final state correlations: Status and open questionsDec 21 2012The recent appreciation of the importance of event-by-event fluctuations in relativistic heavy-ion collisions has lead to a large amount of diverse theoretical and experimental activity. In particular, there is significant interest in understanding the ... More

Conceptual Design of a Micron-Scale Atomic ClockJul 31 2007A theoretical proposal for reducing an entire atomic clock to micron dimensions. A phosphorus or nitrogen atom is introduced into a fullerene cage. This endohedral fullerene is then coated with an insulating shell and a number of them are deposited as ... More

Broccoli curves and the tropical invariance of Welschinger numbersApr 15 2011Sep 11 2013In this paper we introduce broccoli curves, certain plane tropical curves of genus zero related to real algebraic curves. The numbers of these broccoli curves through given points are independent of the chosen points - for arbitrary choices of the directions ... More

Non-equilibrium dilepton production in hadronic transport approachesNov 28 2016In this work the non-equilibrium dilepton production from a hadronic transport approach (SMASH) is presented. The dilepton emission from the hadronic stage is of interest for current HADES results measured at GSI in the beam energy range from 1.25 - 3.5 ... More

Tropical mirror symmetry in dimension oneSep 27 2018We prove a tropical mirror symmetry theorem for descendant Gromov-Witten invariants of the elliptic curve, generalizing a tropical mirror symmetry theorem for Hurwitz numbers of the elliptic curve. For the case of the elliptic curve, the tropical version ... More

Tropical moduli spaces of stable maps to a curveMay 23 2017We construct moduli spaces of rational covers of an arbitrary smooth tropical curve in R^r as tropical varieties. They are contained in the balanced fan parametrizing tropical stable maps of the appropriate degree to R^r. The weights of the top-dimensional ... More

Tropical surface singularitiesJun 14 2011Sep 14 2012In this paper, we study tropicalisations of singular surfaces in toric threefolds. We completely classify singular tropical surfaces of maximal-dimensional type, show that they can generically have only finitely many singular points, and describe all ... More

Attenuation of acoustic waves in glacial ice and salt domesJun 27 2005Two classes of natural solid media (glacial ice and salt domes) are under consideration as media in which to deploy instruments for detection of neutrinos with energy >1e18 eV. Though insensitive to 1e11 to 1e16 eV neutrinos for which observatories (e.g., ... More

Life in solid iceJul 02 2005Some microbes appear to be able to metabolize in glacial ice or permafrost. The rate depends on temperature, nutrient level, and bioelement availability, among other factors. I have developed a plausible argument that they do this while confined in veins ... More

Cluster algebraic interpretation of infinite friezesNov 09 2016Originally studied by Conway and Coxeter, friezes appeared in various recreational mathematics publications in the 1970s. More recently, in 2015, Baur, Parsons, and Tschabold constructed periodic infinite friezes and related them to matching numbers in ... More

On directions determined by subsets of vector spaces over finite fieldsOct 05 2010Jul 30 2015We prove that if a subset of a $d$-dimensional vector space over a finite field with $q$ elements has more than $q^{d-1}$ elements, then it determines all the possible directions. If a set has more than $q^k$ elements, it determines a $k$-dimensional ... More

Echoes from the Abyss: Evidence for Planck-scale structure at black hole horizonsDec 01 2016In classical General Relativity (GR), an observer falling into an astrophysical black hole is not expected to experience anything dramatic as she crosses the event horizon. However, tentative resolutions to problems in quantum gravity, such as the cosmological ... More

Psi-floor diagrams and a Caporaso-Harris type recursionMar 10 2010Jan 06 2012Floor diagrams are combinatorial objects which organize the count of tropical plane curves satisfying point conditions. In this paper we introduce Psi-floor diagrams which count tropical curves satisfying not only point conditions but also conditions ... More

Tropical curves with a singularity in a fixed pointSep 10 2009Mar 26 2012In this paper, we study tropicalisations of families of curves with a singularity in a fixed point. The tropicalisation of such a family is a linear tropical variety. We describe its maximal dimensional cones using results about linear tropical varieties ... More

Enumeration of Complex and Real Surfaces via Tropical GeometryMar 30 2015Aug 23 2018We prove a correspondence theorem for singular tropical surfaces in real three space, which recovers singular algebraic surfaces in an appropriate toric three-fold that tropicalize to a given singular tropical surface. Furthermore, we develop a three-dimensional ... More

The tropical $j$-invariantMar 27 2008Mar 31 2008If (Q,A) is a marked polygon with one interior point, then a general polynomial f in K[x,y] with support A defines an elliptic curve C on the toric surface X_A. If K has a non-archimedean valuation into the real numbers we can tropicalize C to get a tropical ... More

Medium-modified Jets and Initial State Fluctuations as Sources of Charge Correlations Measured at RHICAug 23 2010Jan 31 2011We investigate the contribution of medium-modified jets and initial state fluctuations to the asymmetry in charged particle production with respect to the reaction plane. This asymmetry has been suggested as a compelling signature of the Chiral Magnetic ... More

Counts of (tropical) curves in $E\times \mathbb{P}^1$ and Feynman integralsDec 12 2018We study generating series of Gromov-Witten invariants of $E\times\mathbb{P}^1$ and their tropical counterparts. Using tropical degeneration and floor diagram techniques, we can express the generating series as sums of Feynman integrals, where each summand ... More

The spectral difference between solar flare HXR coronal and footpoint sources due to wave-particle interactionsMar 11 2011Investigate the spatial and spectral evolution of hard X-ray (HXR) emission from flare accelerated electron beams subject to collisional transport and wave-particle interactions in the solar atmosphere. We numerically follow the propagation of a power-law ... More

Transmission spectral properties of clouds for hot Jupiter exoplanetsSep 26 2014Sep 30 2014Clouds have an important role in the atmospheres of planetary bodies. It is expected that, like all the planetary bodies in our solar system, exoplanet atmospheres will also have substantial cloud coverage, and evidence is mounting for clouds in a number ... More

Numerical Sets, Core Partitions, and Integer Points in PolytopesSep 21 2015We study a correspondence between numerical sets and integer partitions that leads to a bijection between simultaneous core partitions and the integer points of a certain polytope. We use this correspondence to prove combinatorial results about core partitions. ... More

Multi-thermal dynamics and energetics of a coronal mass ejection in the low solar atmosphereDec 21 2012The aim of this work is to determine the multi-thermal characteristics and plasma energetics of an eruptive plasmoid and occulted flare observed by Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA). We study an event from 03-Nov-2010 (peaking ... More

Gaps in Protoplanetary Disks as Signatures of Planets: I. Methodology and ValidationFeb 15 2012We examine the observational consequences of partial gaps being opened by planets in protoplanetary disks. We model the disk using a static alpha-disk model with detailed radiative transfer, parametrizing the shape and size of the partially cleared gaps ... More

Projectiles, pendula, and special relativityJan 08 2005The kind of flat-earth gravity used in introductory physics appears in an accelerated reference system in special relativity. From this viewpoint, we work out the special relativistic description of a ballistic projectile and a simple pendulum, two examples ... More

Normal forces in stationary spacetimesJan 30 2004For geodesic motion of a particle in a stationary spacetime the $U_0$ component of particle 4-velocity is constant and is considered to be a conserved mechanical energy. We show that this concept of a conserved mechanical energy can be extended to particles ... More