Results for "Katherine Driggs-Campbell"

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Improved Robustness and Safety for Autonomous Vehicle Control with Adversarial Reinforcement LearningMar 08 2019To improve efficiency and reduce failures in autonomous vehicles, research has focused on developing robust and safe learning methods that take into account disturbances in the environment. Existing literature in robust reinforcement learning poses the ... More
Simulating Emergent Properties of Human Driving Behavior Using Multi-Agent Reward Augmented Imitation LearningMar 14 2019Recent developments in multi-agent imitation learning have shown promising results for modeling the behavior of human drivers. However, it is challenging to capture emergent traffic behaviors that are observed in real-world datasets. Such behaviors arise ... More
Identifying Modes of Intent from Driver Behaviors in Dynamic EnvironmentsMay 21 2015In light of growing attention of intelligent vehicle systems, we propose developing a driver model that uses a hybrid system formulation to capture the intent of the driver. This model hopes to capture human driving behavior in a way that can be utilized ... More
DropoutDAgger: A Bayesian Approach to Safe Imitation LearningSep 18 2017While imitation learning is becoming common practice in robotics, this approach often suffers from data mismatch and compounding errors. DAgger is an iterative algorithm that addresses these issues by continually aggregating training data from both the ... More
HG-DAgger: Interactive Imitation Learning with Human ExpertsOct 05 2018Imitation learning has proven to be useful for many real-world problems, but approaches such as behavioral cloning suffer from data mismatch and compounding error issues. One attempt to address these limitations is the DAgger algorithm, which uses the ... More
EnsembleDAgger: A Bayesian Approach to Safe Imitation LearningJul 22 2018While imitation learning is often used in robotics, this approach often suffers from data mismatch and compounding errors. DAgger is an iterative algorithm that addresses these issues by aggregating training data from both the expert and novice policies, ... More
Experimental Design for Human-in-the-Loop Driving SimulationsJan 20 2014This report describes a new experimental setup for human-in-the-loop simulations. A force feedback simulator with four axis motion has been setup for real-time driving experiments. The simulator will move to simulate the forces a driver feels while driving, ... More
People as Sensors: Imputing Maps from Human ActionsNov 03 2017Jan 08 2019Despite growing attention in autonomy, there are still many open problems, including how autonomous vehicles will interact and communicate with other agents, such as human drivers and pedestrians. Unlike most approaches that focus on pedestrian detection ... More
The under-explored radio-loudness of quasars and the possibility of radio-source--environment interactionsJun 05 2003I demonstrate that radio observations in the literature to date of optically-selected quasars are largely inadequate to reveal the full extent of their jet-activity. I discuss a recent example of an optically-powerful quasar, which is radio-quiet according ... More
Review of Observational Evidence for Dark Matter in the Universe and in upcoming searches for Dark StarsDec 20 2008Over the past decade, a consensus picture has emerged in which roughly a quarter of the universe consists of dark matter. The observational evidence for the existence of dark matter is reviewed: rotation curves of galaxies, weak lensing measurements, ... More
Extinction debt repayment via timely habitat restorationMar 25 2018Habitat destruction threatens the viability of many populations, but its full consequences can take considerable time to unfold. Much of the discourse surrounding extinction debts--the number of species that persist transiently following habitat loss, ... More
Radio-loud and radio-quiet quasars: one population, different epochs of observationMar 05 2008I bring together evidence for the rapidity with which quasars' radio synchrotron lobe emission fades and for the intermittency with which jet plasma is ejected from individual quasars and radio galaxies and affirm the picture presented by Nipoti et al ... More
Escape, Accretion or Star Formation? The Competing Depleters of Gas in the Quasar Markarian 231Feb 02 2015Feb 16 2015We report on high resolution CO(1-0), CS(2-1) and 3mm continuum Combined Array for Research in Millimeter Astronomy (CARMA) observations of the molecular outflow host and nearest quasar Markarian 231. We use the CS(2-1) measurements to derive a dense ... More
A Dynamical Systems Framework for Resilience in EcologySep 28 2015Rising interest in the resilience of ecological systems has spawned diverse interpretations of the term's precise meaning. This paper classifies and explores definitions of resilience from the ecological literature using a dynamical systems framework. ... More
The Dark Side of the UniverseAug 11 2005I will begin by reviewing the evidence for Dark Matter in the Universe, as well as the candidates for dark matter. At most 20% of the dark matter in galaxies can be in the form of MACHOs (Massive Compact Halo Objects); the remainder appears to be some ... More
Matter and Gravity in Warped Extradimensional Models: Reinterpreting Randall-SundrumOct 16 2005Warped extra dimension claims remarkable success: solving the hierarchy problem; explaining hierarchies in particle phenomenology; yielding standard cosmology, plus interesting nonstandard scenarios. Yet it has marked shortcomings: we over-rely on a single ... More
A Coupling of Pseudo Nambu Goldstone Bosons to Other Scalars and Role in Double Field InflationMay 19 1994We find a coupling of Pseudo Nambu Goldstone bosons (PNGBs) to other (ordinary) scalars, and consider its importance in various contexts. Our original motivation was the model of Double Field inflation [1]. We also briefly consider the role of this coupling ... More
Skew-enriched categoriesSep 05 2017Oct 07 2018This paper introduces a skew variant of the notion of enriched category, suitable for enrichment over a skew-monoidal category, the main novelty of which is that the elements of the enriched hom-objects need not be in bijection with the morphisms of the ... More
How strict is strictification?Feb 21 2018Oct 26 2018The subject of this paper is the higher structure of the strictification adjunction, which relates the two fundamental bases of three-dimensional category theory: the $\mathbf{Gray}$-category of $2$-categories and the tricategory of bicategories. We show ... More
Criticality revealed through quench dynamics in a many-body systemAug 18 2016We examine the dynamics after a sudden quench in the magnetic field of the Lipkin-Meshkov-Glick model. Starting from the groundstate and by employing the Loschmidt echo, we see manifestly different dynamics are present if the system is quenched through ... More
Essential spectrum in vibrations of thin shells in membrane approximation. Propagation of singularitiesFeb 28 2005The spectral problem of thin elastic shells in membrane approximation does not satisfy the classical properties of compactness and so there exists an essential spectrum. In the first part, we propose to determinate this spectrum and the weakness directions ... More
sPHENIX: The next generation heavy ion detector at RHICNov 09 2016sPHENIX is a new collaboration and future detector project at Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC). It seeks to answer fundamental questions on the nature of the quark gluon plasma (QGP), including its temperature dependence ... More
Calculation of Particle Production by Nambu Goldstone Bosons with Application to Inflation Reheating and BaryogenesisOct 22 1994A semiclassical calculation of particle production by a scalar field in a potential is performed. We focus on the particular case of production of fermions by a Nambu-Goldstone boson $\theta$. We have derived a (non)local equation of motion for the $\theta$-field ... More
Exploring the Correlations between Globular Cluster Populations and Supermassive Black Holes in Giant GalaxiesOct 16 2012This paper presents an analysis of the correlation between the number of globular clusters (N_GC) in giant galaxies and the mass of the galaxies' central supermassive black hole (M_SMBH). I construct a sample of 20 elliptical, spiral, and S0 galaxies ... More
Bell Inequalities with Communication AssistanceMay 13 2014In this paper we consider the possible correlations between two parties using local machines and shared randomness with an additional amount of classical communication. This is a continuation of the work initiated by Bacon and Toner in Ref. [\textit{Phys. ... More
Patterns of Negative Shifts and Beta-ShiftsDec 14 2015Jan 29 2016The $\beta$-shift is the transformation from the unit interval to itself that maps $x$ to the fractional part of $\beta x$. Permutations realized by the relative order of the elements in the orbits of these maps have been studied for positive integer ... More
The sensual Apollonian circle packingAug 23 2012Mar 12 2014The curvatures of the circles in integral Apollonian circle packings, named for Apollonius of Perga (262-190 BC), form an infinite collection of integers whose Diophantine properties have recently seen a surge in interest. Here, we give a new description ... More
$k$-means: Fighting against Degeneracy in Sequential Monte Carlo with an Application to TrackingNov 13 2015For regular particle filter algorithm or Sequential Monte Carlo (SMC) methods, the initial weights are traditionally dependent on the proposed distribution, the posterior distribution at the current timestamp in the sampled sequence, and the target is ... More
Bayesian Epidemic Detection in Multiple PopulationsSep 14 2015Traditional epidemic detection algorithms make decisions using only local information. We propose a novel approach that explicitly models spatial information fusion from several metapopulations. Our method also takes into account cost-benefit considerations ... More
Axions, Inflation and the Anthropic PrincipleNov 03 2009The QCD axion is the leading solution to the strong-CP problem, a dark matter candidate, and a possible result of string theory compactifications. However, for axions produced before inflation, symmetry-breaking scales of $f_a \gtrsim 10^{12}$ GeV (which ... More
Twisted Alice Loops as MonopolesApr 17 2003Dec 05 2003Symmetry breaking can produce ``Alice'' strings, which alter scattered charges and carry monopole number and charge when twisted into loops. We apply recent topological results, fixing Alice strings' stability and prescribing their twisting into loops ... More
Integral points on elliptic curves and explicit valuations of division polynomialsAug 15 2011Dec 29 2014Assuming Lang's conjectured lower bound on the heights of non-torsion points on an elliptic curve, we show that there exists an absolute constant C such that for any elliptic curve E/Q and non-torsion point P in E(Q), there is at most one integral multiple ... More
Free boundary stable hypersurfaces in manifolds with density and rigidity resultsNov 08 2013Let $M$ be a weighted manifold with boundary $\partial M$, i.e., a Riemannian manifold where a density function is used to weight the Riemannian Hausdorff measures. In this paper we compute the first and the second variational formulas of the interior ... More
Instability and Subsequent Evolution of Electroweak BubblesAug 04 1992Bubbles in a first-order electroweak phase transition are nucleated with radii $R_0$ and expand with velocity $v$. If $v$ is subsonic, a bubble becomes unstable to non-spherical perturbations when its radius is roughly $10^4\, R_0$. These perturbations ... More
Symmetry in the changing jets of SS433 and its true distance from usOct 19 2004We present the deepest yet radio image of the Galactic jet source, SS433, which reveals over two full precession cycles (> 2 x 163 days) of the jet axis. Systematic and identifiable deviations from the traditional kinematical model for the jets are found: ... More
Effects of CP-Violation in Neutralino Scattering and AnnihilationJan 10 2000We summarize our paper hep-ph/9908390, where we find that in some regions of supersymmetric parameter space, CP violating effects that mix the CP-even and CP-odd Higgs bosons can enhance the neutralino annihilation rate by factors of 10^6, and reduce ... More
Jet propulsion of wind ejecta from a major flare in the black hole microquasar SS433Apr 14 2011We present direct evidence, from Adaptive-Optics near-infra-red imaging, of the jets in the Galactic microquasar SS433 interacting with enhanced wind-outflow off the accretion disc that surrounds the black hole in this system. Radiant quantities of gas ... More
Concentration of the number of solutions of random planted CSPs and Goldreich's one-way candidatesApr 30 2015This paper shows that the logarithm of the number of solutions of a random planted $k$-SAT formula concentrates around a deterministic $n$-independent threshold. Specifically, if $F^*_{k}(\alpha,n)$ is a random $k$-SAT formula on $n$ variables, with clause ... More
A Topological Criterion for Alice StringsApr 17 2003Dec 05 2003Symmetry breaking can produce ``Alice'' strings, which alter scattered charges and carry monopole number and charge when twisted into loops. Alice behavior arises algebraically, when a string's untraced Wilson loop obstructs unbroken symmetries -- a fragile ... More
A Wide-Field Survey of the Globular Cluster Systems of Giant GalaxiesMay 12 2006I present selected results from a wide-field CCD survey of the globular cluster systems of giant galaxies, including showing how measurements of the specific frequency of metal-poor globular clusters can constrain the redshift of their formation.
Odd behavior in the coefficients of reciprocals of binary power seriesNov 06 2014Let $\mathcal{A}$ be a finite subset of $\mathbb{N}$ including $0$ and $f_\mathcal{A}(n)$ be the number of ways to write $n=\sum_{i=0}^{\infty}\epsilon_i2^i$, where $\epsilon_i\in\mathcal{A}$. The sequence $\left(f_\mathcal{A}(n)\right) \bmod 2$ is always ... More
The space of graded traces for holomorphic VOAs of small central chargeJun 12 2006It is one of the remarkable results of vertex operator algebras (VOAs) that the graded traces (one-point correlation functions) of holomorphic VOAs are modular functions. This paper explores the question of which modular functions arise as the graded ... More
Active matter clusters at interfacesApr 04 2016Collective and directed motility or swarming is an emergent phenomenon displayed by many self-organized assemblies of active biological matter such as clusters of embryonic cells during tissue development, cancerous cells during tumor formation and metastasis, ... More
Probing Dark Energy Using Its Density Instead of Its Equation of StateFeb 09 2004The variation of dark energy density with redshift, $\rho_X(z)$, provides a critical clue to the nature of dark energy. Since $\rho_X(z)$ depends on the dark energy equation of state $w_X(z)$ through an integral, $\rho_X(z)$ can be constrained more tightly ... More
Indirect Detection of a Light Higgsino Motivated by Collider DataSep 16 1996Kane and Wells recently argued that collider data point to a Higgsino-like lightest supersymmetric partner which would explain the dark matter in our Galactic halo. They discuss direct detection of such dark-matter particles in laboratory detectors. Here, ... More
Fluid Interpretation of Cardassian ExpansionSep 26 2002Oct 13 2003A fluid interpretation of Cardassian expansion is developed. Here, the Friedmann equation takes the form $H^2 = g(\rho_M)$ where $\rho_M$ contains only matter and radiation (no vacuum). The function $g(\rhom)$ returns to the usual $8\pi\rhom/(3 m_{pl}^2)$ ... More
On degree sequences forcing the square of a Hamilton cycleDec 10 2014Jul 30 2015A famous conjecture of P\'osa from 1962 asserts that every graph on $n$ vertices and with minimum degree at least $2n/3$ contains the square of a Hamilton cycle. The conjecture was proven for large graphs in 1996 by Koml\'os, S\'ark\"ozy and Szemer\'edi. ... More
Known Unknowns of Dark Matter Annihilation over Cosmic TimeSep 30 2013Jan 21 2014Dark matter self-annihilation holds promise as one of the most robust mechanisms for the identification of the particle responsible for the Universe's missing mass. In this work, I examine the evolution of the dark matter annihilation power produced by ... More
The optically-powerful quasar E1821+643 is associated with a 300-kpc scale FRI radio structureOct 06 2001We present a deep image of the optically-powerful quasar E1821+643 at 18cm made with the Very Large Array (VLA). This image reveals radio emission, over 280 kpc in extent, elongated way beyond the quasar's host galaxy. Its radio structure has decreasing ... More
High-z radio galaxies and the `Youth-Redshift Degeneracy'Oct 08 1999We discuss a unifying explanation for many `trends with redshift' of radio galaxies which includes the relevance of their ages (time since their jet triggering event), and the marked dependence of their ages on redshift due to the selection effect of ... More
CP Violation measurements in B to charm decays at BaBarOct 05 2006This article summarises measurements of time-dependent CP asymmetries in decays of neutral B mesons to charm final states using data collected by the BaBar detector at the PEP-II asymmetric-energy B-factory. All results are preliminary unless otherwise ... More
The effects of cyclical simulation on the axon hillock diameter of murine intracortical neuronsMar 22 2018Changes to the axon hillock in frequently firing neurons are known to be important predictors of early disease states. Studying this phenomenon is critical to understanding the first insult implicated in multiple neuro-degenerative disorders. To study ... More
Systematic motions in the Galactic plane found in the Hipparcos Catalogue using Herschel's MethodOct 16 2005Two motions in the galactic plane have been detected and characterized, based on the determination of a common systematic component in Hipparcos catalogue proper motions. The procedure is based only on positions, proper motions and parallaxes, plus a ... More
The Apollonian structure of Bianchi groupsMay 12 2015Oct 08 2015We study the orbit of $\widehat{\mathbb{R}}$ under the M\"obius action of the Bianchi group $\operatorname{PSL}_2(\mathcal{O}_K)$ on $\widehat{\mathbb{C}}$, where $\mathcal{O}_K$ is the ring of integers of an imaginary quadratic field $K$. The orbit $\mathcal{S}_K$, ... More
A formula for the Dubrovnik polynomial of rational knotsMar 31 2015We provide a formula for the Dubrovnik polynomial of a rational knot in terms of the entries of the tuple associated with a braid-form diagram of the knot. Our calculations can be easily carried out using a computer algebra system.
Sphericons and D-forms: a crocheted connectionMar 01 2016Jun 15 2016Sphericons and D-forms are 3D objects created and described by artists, which have separately received attention in the mathematical literature in the last 15 or so years. The attempt to classify a seamed, crocheted form geometrically led to the observation, ... More
Apparent shape of super-spinning black holesDec 07 2008Feb 03 2009We consider the possibility that astrophysical Black Holes (BHs) can violate the Kerr bound; i.e., they can have angular momentum greater than BH mass, $J > M$. We discuss implications on the BH apparent shape. Even if the bound is violated by a small ... More
A Bound on the Flux of Magnetic Monopoles from Catalysis of Nucleon Decay in White DwarfsApr 15 1998Catalysis of nucleon decay in white dwarfs is used to constrain the abundance of magnetic monopoles arising from Grand Unified Theories. Recent discoveries of the dimmest white dwarf ever observed, WD 1136-286 with $L = 10^{-4.94} L_{\odot}$, place limits ... More
The spectra and energies of classical double radio lobesJan 19 2000We compare two temporal properties of classical double radio sources: i) radiative lifetimes of synchrotron-emitting particles and ii) dynamical source ages. We discuss how these can be quite discrepant from one another, rendering use of the traditional ... More
Chamber Surface Roughness and Electron Cloud for the Advanced Photon Source Superconducting UndulatorJul 19 2013The electron cloud is a possible heat source in the superconducting undulator (SCU) designed for the Advanced Photon Source (APS), a 7-GeV electron synchrotron radiation source at Argonne National Laboratory. In electron cloud generation extensive research ... More
The X-ray and radio-emitting plasma lobes of 4C23.56: further evidence of recurrent jet activity and high acceleration energiesAug 30 2010New Chandra observations of the giant (0.5 Mpc) radio galaxy 4C23.56 at z = 2.5 show X-rays in a linear structure aligned with its radio emission, but anti-correlated with the detailed radio structure. Consistent with the powerful, high-z giant radio ... More
Gravity Waves from Chain InflationNov 14 2008Chain inflation proceeds through a series of first order phase transitions, which can release considerable gravitational waves (GW). We demonstrate that bubble collisions can leave an observable signature for future high-frequency probes of GWs, such ... More
Dark Matter: A PrimerJun 12 2010Jan 24 2011Dark matter is one of the greatest unsolved mysteries in cosmology at the present time. About 80% of the universe's gravitating matter is non-luminous, and its nature and distribution are for the most part unknown. In this paper, we will outline the history, ... More
Charge Violation and Alice Behavior in Global and Textured StringsMar 28 2001Spontaneous breaking of global symmetries can produce ``Alice'' strings: line defects which make unbroken symmetries multivalued, induce apparent charge violation via Aharonov-Bohm interactions, and form point defects when twisted into loops. We demonstrate ... More
Skyrmions and Semilocal Strings in CosmologyApr 05 1993It has been pointed out that cosmic string solutions can exist in gauge field theories with broken symmetry even when $\pi _1(G/H)$ is trivial. The stability of such semilocal defects is not guaranteed by topology and depends on dynamical considerations. ... More
Visualising the arithmetic of imaginary quadratic fieldsOct 01 2014Mar 28 2015We study the orbit of $\mathbb{R}$ under the Bianchi group $\operatorname{PSL}_2(\mathcal{O}_K)$, where $K$ is an imaginary quadratic field. The orbit, called a Schmidt arrangement $\mathcal{S}_K$, is a geometric realisation, as an intricate circle packing, ... More
Local Galois theory in dimension two: Second editionJul 17 2009We prove a generalization of Shafarevich's Conjecture for fields of Laurent series in two variables over an arbitrary field. While not projective, the absolute Galois group of such a field is shown to be semi-free. We also show that the function field ... More
D-analogues of q-shifted factorial and the q-Kummer sumDec 10 2012Recently, the concept of a D-analogue was introduced by the author. This is a Dirichlet series analogue for the already known and well researched hypergeometric q-series. we consider the D-analogues of the q-binomial coefficients, and a D-analogue of ... More
Polylogarithm approaches to Riemann Zeta function zeroesDec 10 2012We use visible point vector identities to examine polylogarithms in the neighbourhood of the Riemann zeta function zeroes. New formulas limiting to the trivial zeroes and to the critical line on the zeta function are given. Similar results arise from ... More
On the complex-representable excluded minors for real-representabilityJan 26 2018We show that each real-representable matroid is a minor of a complex-representable excluded minor for real-representability.
Adaptive time-stepping for Stochastic Partial Differential Equations with non-Lipschitz driftDec 21 2018We introduce an explicit, adaptive time-stepping scheme for simulation of SPDEs with non-Lipschitz drift coefficients. Strong convergence is proven for the full space-time discretisation with multiplicative noise by considering the space and time discretisation ... More
Derived Koszul Duality and Topological Hochschild HomologyJan 21 2014Motivated by a result from string topology, we prove a duality in topological Hochschild homology (THH). The duality relates the THH of an E_1-algebra spectrum and the THH of its derived Koszul dual algebra under certain compactness conditions. The result ... More
Ionospheric Corrections via PIM and Real-Time DataJul 29 1999We describe a method for removing ionospheric effects from single-frequency radio data a posteriori. This method is based on a theoretical climatological model developed by the USAF, which returns electron density as a function of position and time along ... More
Decoherence in open Majorana systemsFeb 19 2015Jul 01 2015Coupling to a thermal bath leads to decoherence of stored quantum information. For a system of Gaussian fermions, the fermionic analog of linear or Gaussian optics, these dynamics can be elegantly and efficiently described by evolution of the system's ... More
How to exploit local information when distilling entanglementJun 08 2009Sep 10 2009Distillation protocols enable generation of high quality entanglement even in the presence of noise. Existing protocols ignore the presence of local information in mixed states produced from some noise sources such as photon loss, amplitude damping or ... More
Migration of two massive planets into (and out of) first order mean motion resonancesJun 03 2015We consider the dynamical evolution of two planets orbiting in the vicinity of a first order mean motion reso- nance while simultaneously undergoing eccentricity damping and convergent migration. Following Goldreich & Schlichting (2014), we include a ... More
Spectral ageing: a new age perspectiveSep 18 2002We present an up-to-date critique of the physical basis for the spectral ageing method. We find that the number of cases where this method may be meaningfully applied to deduce the ages of classical double radio sources is small indeed. This critique ... More
The Ultimate Fate of Life in an Accelerating UniverseMay 17 2002May 24 2002The ultimate fate of life in a universe with accelerated expansion is considered. Previous work showed that life cannot go on indefinitely in a universe dominated by a cosmological constant. In this paper we consider instead other models of acceleration ... More
Self-Directed Channel Memristor for High Temperature OperationAug 18 2016Ion-conducting memristors comprised of the layered chalcogenide materials Ge2Se3/SnSe/Ag are described. The memristor, termed a self-directed channel (SDC) device, can be classified as a generic memristor and can tolerate continuous high temperature operation ... More
An Adaptive Data Representation for Robust Point-Set Registration and MergingNov 13 2015This paper presents a framework for rigid point-set registration and merging using a robust continuous data representation. Our point-set representation is constructed by training a one-class support vector machine with a Gaussian radial basis function ... More
Natural Inflation: Consistency with Cosmic Microwave Background Observations of Planck and BICEP2Mar 20 2014May 29 2014Natural inflation is a good fit to all cosmic microwave background (CMB) data and may be the correct description of an early inflationary expansion of the Universe. The large angular scale CMB polarization experiment BICEP2 has announced a major discovery, ... More
The Mad Era: A Possible New Resolution to the Horizon, Flatness, and Monopole ProblemsNov 10 1992A cosmology with a dynamical Planck mass $m_{pl}$ is shown to solve the horizon and monopole problems (and possibly flatness) if there is an early MAD (modified aging) era where the universe becomes older than in the standard model as a result of a large ... More
The Dynamics and Stability of Circumbinary OrbitsAug 20 2011We numerically investigate the dynamics of orbits in 3D circumbinary phase-space as a function of binary eccentricity and mass fraction. We find that inclined circumbinary orbits in the elliptically-restricted three-body problem display a nodal libration ... More
Universal amplitude ratios and Coxeter geometry in the dilute A modelApr 10 2002The leading excitations of the dilute $A_L$ model in regime 2 are considered using analytic arguments. The model can be identified with the integrable $\phi_{1,2}$ perturbation of the unitary minimal series $M_{L,L+1}$. It is demonstrated that the excitation ... More
Bounding the fractional chromatic number of $K_Δ$-free graphsJun 11 2012Mar 30 2013King, Lu, and Peng recently proved that for $\Delta\geq 4$, any $K_\Delta$-free graph with maximum degree $\Delta$ has fractional chromatic number at most $\Delta-\tfrac{2}{67}$ unless it is isomorphic to $C_5\boxtimes K_2$ or $C_8^2$. Using a different ... More
Distributed quantum information processing with minimal local resourcesApr 11 2007Oct 09 2007We present a protocol for growing graph states, the resource for one-way quantum computing, when the available entanglement mechanism is highly imperfect. The distillation protocol is frugal in its use of ancilla qubits, requiring only a single ancilla ... More
Optimal Entangling Capacity of Dynamical ProcessesJul 08 2010Sep 23 2010We investigate the entangling capacity of dynamical operations when provided with local ancilla. A comparison is made between the entangling capacity with and without the assistance of prior entanglement. An analytic solution is found for the log-negativity ... More
The K-Theory Spectrum of VarietiesMay 12 2015Using a construction closely related to Waldhausen's $S_\bullet$-construction, we produce a spectrum $K(\mathbf{Var}_{/k})$ whose components model the Grothendieck ring of varieties (over a field $k$) $K_0 (\mathbf{Var}_{/k})$. We then produce liftings ... More
Picturing Pinchuk's Plane Polynomial PairDec 05 1998Sergey Pinchuk discovered a class of pairs of real polynomials in two variables that have a nowhere vanishing Jacobian determinant and define maps of the real plane to itself that are not one-to-one. This paper describes the asymptotic behavior of one ... More
Multipartite non-locality in a thermalized Ising spin-chainJun 11 2010Oct 22 2010We study multipartite correlations and non-locality in an isotropic Ising ring under transverse magnetic field at both zero and finite temperature. We highlight parity-induced differences between the multipartite Bell-like functions used in order to quantify ... More
A dissipative scheme to approach the boundary of two-qubit entangled mixed statesDec 19 2008Feb 18 2009We discuss the generation of states close to the boundary-family of maximally entangled mixed states as defined by the use of concurrence and linear entropy. The coupling of two qubits to a dissipation-affected bosonic mode is able to produce a bipartite ... More
On truncated quasi-categoriesOct 26 2018Mar 11 2019For each $n \geq -1$, a quasi-category is said to be $n$-truncated if its hom-spaces are $(n-1)$-types. In this paper we study the model structure for $n$-truncated quasi-categories, which we show can be constructed as the Bousfield localisation of Joyal's ... More
Negative running prevents eternal inflationApr 17 2014Jun 04 2014Current data from the Planck satellite and the BICEP2 telescope favor, at around the $2 \sigma$ level, negative running of the spectral index of curvature perturbations from inflation. We show that for negative running $\alpha < 0$, the curvature perturbation ... More
The inevitable youthfulness of known high-redshift radio galaxiesMay 26 1999Radio galaxies can be seen out to very high redshifts, where in principle they can serve as probes of the early evolution of the Universe. Here we show that for any model of radio-galaxy evolution in which the luminosity decreases with time after an initial ... More
The Mass-Function of Low Mass Halo Stars: Limits on Baryonic Halo Dark MatterFeb 10 1996Jun 18 1996We derive mass functions (MF) for halo red dwarfs (the faintest hydrogen burning stars) and then extrapolate to place limits on the total mass of halo brown dwarfs (stars not quite massive enough to burn hydrogen). The mass functions are obtained from ... More
The Scalar Field Potential in Inflationary Models: Reconstruction and Further ConstraintsJan 07 1994In this paper, we present quantitative constraints on the scalar field potential for a general class of inflationary models. (1) We first consider the reconstruction of the inflationary potential for given primordial density fluctuation spectra. Our work ... More
Measurement of planet masses with transit timing variations due to synodic "chopping" effectsOct 31 2014Gravitational interactions between planets in transiting exoplanetary systems lead to variations in the times of transit that are diagnostic of the planetary masses and the dynamical state of the system. Here we show that synodic "chopping" contributions ... More
A Possible Solution to the Horizon Problem: The Mad Era for Massless Scalar Theories of GravityNov 17 1992Extensions of Einstein gravity which allow the gravitational constant $G$ to change with time as the universe evolves may provide a resolution to the horizon problem without invoking a period of vacuum domination and without the subsequent entropy violation. ... More
A superlocal version of Reed's ConjectureAug 26 2012Nov 15 2014Reed's well-known $\omega$, $\Delta$, $\chi$ conjecture proposes that every graph satisfies $\chi \leq \lceil \frac 12(\Delta+1+\omega)\rceil$. The second author formulated a {\em local strengthening} of this conjecture that considers a bound supplied ... More
Analysis of a Hubble Space Telescope Search for Red Dwarfs: Limits on Baryonic Matter in the Galactic HaloJul 25 1995Nov 03 1995We re-examine a deep {\it Hubble Space Telescope} pencil-beam search for red dwarfs, stars just massive enough to burn Hydrogen. The authors of this search (Bahcall, Flynn, Gould \& Kirhakos 1994) found that red dwarfs make up less than 6\% of the galactic ... More