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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

Topological PhotonicsFeb 12 2018Topological photonics is a rapidly-emerging field of research in which geometrical and topological ideas are exploited to design and control the behavior of light. Drawing inspiration from the discovery of the quantum Hall effects and topological insulators ... 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

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

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

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.

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

Using simplicial volume to count maximally broken Morse trajectoriesJun 15 2015Given a closed Riemannian manifold of dimension $n$ and a Morse-Smale function, there are finitely many $n$-part broken trajectories of the negative gradient flow. We show that if the manifold admits a hyperbolic metric, then the number of $n$-part broken ... More

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

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

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

Sensitivity of codispersion to noise and error in ecological and environmental dataJan 24 2018Codispersion analysis is a new statistical method developed to assess spatial covariation between two spatial processes that may not be isotropic or stationary. Its application to anisotropic ecological datasets have provided new insights into mechanisms ... 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

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

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

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

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

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

Automorphism groups of compact complex supermanifoldsJun 03 2015Let $\mathcal M$ be a compact complex supermanifold. We prove that the set $\mathrm{Aut}_{\bar 0}(\mathcal M)$ of automorphisms of $\mathcal M$ can be endowed with the structure of a complex Lie group acting holomorphically on $\mathcal M$, so that its ... 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

Sieved Enumeration of Interval Orders and Other Fishburn StructuresFeb 18 2015Mar 10 2015Following a result of Eriksen and Sj\"{o}strand (2014) we detail a technique to construct structures following the Fishburn distribution from appropriate Mahonian structures. This technique is introduced on a bivincular pattern of Bousquet-M\'elou et ... More

Sky subtraction at the Poisson limit with fibre-optic multi-object spectroscopyJul 05 2010We report on the limitations of sky subtraction accuracy for long duration fibre-optic multi-object spectroscopy of faint astronomical sources during long duration exposures. We show that while standard sky subtraction techniques yield accuracies consistent ... More

Tropical covers of curves and their moduli spacesMar 26 2013We define the tropical moduli space of covers of a tropical line in the plane as weighted abstract polyhedral complex, and the tropical branch map recording the images of the simple ramifications. Our main result is the invariance of the degree of the ... 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

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

Effects of Co substitution on thermodynamic and transport properties and anisotropic $H_{c2}$ in Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ single crystalsNov 11 2008Single crystalline samples of Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ with $x < 0.12$ have been grown and characterized via microscopic, thermodynamic and transport measurements. With increasing Co substitution, the thermodynamic and transport signatures of the ... 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

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

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

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

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

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

Decomposing labeled interval orders as pairs of permutationsMay 10 2014Oct 21 2014We introduce ballot matrices, a signed combinatorial structure whose definition naturally follows from the generating function for labeled interval orders. A sign reversing involution on ballot matrices is defined. We show that matrices fixed under this ... More

How to repair tropicalizations of plane curves using modificationsSep 25 2014Tropical geometry is sensitive to embeddings of algebraic varieties inside toric varieties. The purpose of this paper is to advertise tropical modifications as a tool to locally repair bad embeddings of plane curves, allowing the re-embedded tropical ... More

Word Length Perturbations in Certain Symmetric Presentations of Dihedral GroupsDec 09 2015Given a finite group, $G$, with a generating subset $S$, there is a well-established notion of length for an element $g \in G$ given in terms of the minimal length expression for $g$ as a product of elements from $S$. Recently, quantities denoted $\lambda_{1}(G,S)$ ... More

Spending too much time at the Galactic bar: chaotic fanning of the Ophiuchus streamJan 25 2016The Ophiuchus stellar stream is peculiar: (1) its length is short given the age of its constituent stars, and (2) several probable member stars that lie close in both sky position and velocity have dispersions in these dimensions that far exceed those ... More

A re-interpretation of the Triangulum-Andromeda stellar clouds: a population of halo stars kicked out of the Galactic diskMar 30 2015Jul 31 2015The Triangulum-Andromeda stellar clouds (TriAnd1 and TriAnd2) are a pair of concentric ring- or shell-like over-densities at large $R$ ($\approx$ 30 kpc) and $Z$ ($\approx$ -10 kpc) in the Galactic halo that are thought to have been formed from the accretion ... More

Inferring the gravitational potential of the Milky Way with a few precisely measured starsMay 26 2014The dark matter halo of the Milky Way is expected to be triaxial and filled with substructure. It is hoped that streams or shells of stars produced by tidal disruption of stellar systems will provide precise measures of the gravitational potential to ... 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

Photoproduction of the doubly-strange Xi HyperonsFeb 05 2004We report on the first measurement of exclusive Xi- and Xi0 photoproduction. The Xi- states are produced in the reaction gamma p --> K+ K+ Xi-, and the Xi0 states in gamma p --> K+ K+ pi- Xi0. Identification is made by the unique mass measured as the ... 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

A Medieval Multiverse: Mathematical Modelling of the 13th Century Universe of Robert GrossetesteMar 04 2014Mar 10 2014In his treatise on light, written in about 1225, Robert Grosseteste describes a cosmological model in which the Universe is created in a big-bang like explosion and subsequent condensation. He postulates that the fundamental coupling of light and matter ... More

YSix closely related YbT$_2$Zn$_{20}$ (T = Fe, Co, Ru, Rh, Os, Ir) heavy fermion compounds with large local moment degeneracyAug 18 2006Feb 20 2007Heavy fermion compounds represent one of the most strongly correlated forms of electronic matter and give rise to low temperature states that range from small moment ordering to exotic superconductivity, both of which are often in close proximity to quantum ... 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

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

The Effects of Turbulence on Three-Dimensional Magnetic Reconnection at the MagnetopauseApr 27 2016Jun 07 2016Two- and three-dimensional particle-in-cell simulations of a recent encounter of the Magnetospheric Multiscale Mission (MMS) with an electron diffusion region at the magnetopause are presented. While the two-dimensional simulation is laminar, turbulence ... 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

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

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

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

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

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

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

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

The combinatorics of real double Hurwitz numbers with real positive branch pointsSep 29 2014Aug 25 2015We investigate the combinatorics of real double Hurwitz numbers with real positive branch points using the symmetric group. Our main focus is twofold. First, we prove correspondence theorems relating these numbers to counts of tropical real covers and ... 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

The j-invariant of a plane tropical cubicSep 24 2007Several results in tropical geometry have related the j-invariant of an algebraic plane curve of genus one to the cycle length of a tropical curve of genus one. In this paper, we prove that for a plane cubic over the field of Puiseux series the negative ... More

An algorithm for lifting points in a tropical varietyMay 16 2007Jul 28 2009The aim of this paper is to give a constructive proof of one of the basic theorems of tropical geometry: given a point on a tropical variety (defined using initial ideals), there exists a Puiseux-valued ``lift'' of this point in the algebraic variety. ... 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

Enumeration of Complex and Real Surfaces via Tropical GeometryMar 30 2015Jul 20 2015We 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

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

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