Results for "Douglas P. Hamilton"

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Chaotic dust dynamics and implications for the hemispherical color asymmetries of the Uranian satellitesJun 17 2013Dust grains generated by the Uranian irregular satellites will undergo chaotic large-amplitude eccentricity oscillations under the simultaneous action of radiation forces and the highly misaligned quadrupole potentials of the oblate planet and distant ... More
Galileo In-Situ Dust Measurements in Jupiter's Gossamer RingsMar 19 2008During its late orbital mission at Jupiter the Galileo spacecraft made two passages through the giant planet's gossamer ring system. The impact-ionization dust detector on board successfully recorded dust impacts during both ring passages and provided ... More
Three-Body Dynamics with Gravitational Wave EmissionSep 29 2005Nov 21 2005We present numerical three-body experiments that include the effects of gravitational radiation reaction by using equations of motion that include the 2.5-order post-Newtonian force terms, which are the leading order terms of energy loss from gravitational ... More
Three-Body Encounters of Black Holes in Globular ClustersJun 10 2003Jul 01 2003Evidence has been mounting for the existence of black holes with masses from 10^2 to 10^4 M_Solar associated with stellar clusters. Such intermediate-mass black holes (IMBHs) will encounter other black holes in the dense cores of these clusters. The binaries ... More
Three-Body Capture of Irregular Satellites: Application to JupiterNov 06 2009We investigate a new theory of the origin of the irregular satellites of the giant planets: capture of one member of a ~100-km binary asteroid after tidal disruption. The energy loss from disruption is sufficient for capture, but it cannot deliver the ... More
Dynamical Instabilities in High-Obliquity SystemsNov 30 2012High-inclination circumplanetary orbits that are gravitationally perturbed by the central star can undergo Kozai oscillations---large-amplitude, coupled variations in the orbital eccentricity and inclination. We first study how this effect is modified ... More
Radial profiles of the Phoebe ring, a vast debris disk around SaturnApr 11 2016We present observations at optical wavelengths with the Cassini Spacecraft's Imaging Science System of the Phoebe ring, a vast debris disk around Saturn that seems to be collisionally generated by its irregular satellites. The analysis reveals a radial ... More
Finding the trigger to Iapetus' odd global albedo pattern: Dynamics of dust from Saturn's irregular satellitesJun 09 2011The leading face of Saturn's moon Iapetus, Cassini Regio, has an albedo only one tenth that on its trailing side. The origin of this enigmatic dichotomy has been debated for over forty years, but with new data, a clearer picture is emerging. Motivated ... More
The Role of the Kozai-Lidov Mechanism in Black Hole Binary Mergers in Galactic CentersApr 18 2016In order to understand the rate of merger of stellar-mass black hole binaries (BHBs) by gravitational wave (GW) emission it is important to determine the major pathways to merger. We use numerical simulations to explore the evolution of BHBs inside the ... More
Rotation sensing with trapped ionsSep 02 2016We present a protocol for using trapped ions to measure rotations via matter-wave Sagnac interferometry. The trap allows the interferometer to enclose a large area in a compact apparatus through repeated round-trips in a Sagnac geometry. We show how a ... More
Elasticity and Stability of Shape Changing StructuresSep 12 2018As we enter the age of designer matter - where objects can morph and change shape on command - what tools do we need to create shape-shifting structures? At the heart of an elastic deformation is the combination of dilation and distortion, or stretching ... More
Observing Planetary Rings with JWST: Science Justification and Observation RequirementsMar 26 2014Oct 22 2015The James Webb Space Telescope (JWST) will provide unprecedented opportunities to observe the rings and small satellites in our solar system, accomplishing three primary objectives: 1) discovering new rings and moons, 2) unprecedented spectroscopy, and ... More
Fisher Information and Kinetic-energy Functionals: A Dequantization ApproachMay 21 2009We strengthen the connection between Information Theory and quantum-mechanical systems using a recently developed dequantization procedure whereby quantum fluctuations latent in the quantum momentum are suppressed. The dequantization procedure results ... More
Tight lower bound for percolation threshold on a quasi-regular graphApr 30 2014We construct an exact expression for the site percolation threshold p_c on a quasi-regular tree, and a related exact lower bound for a quasi-regular graph. Both are given by the inverse spectral radius of the appropriate Hashimoto matrix used to count ... More
Exponential decay of connectivity and uniqueness in percolation on finite and infinite graphsOct 16 2016We give an upper bound for the uniqueness transition on an arbitrary locally finite graph ${\cal G}$ in terms of the limit of the spectral radii $\rho\left[ H({\cal G}_t)\right]$ of the non-backtracking (Hashimoto) matrices for an increasing sequence ... More
Herschel Observations of Cataclysmic VariablesNov 20 2012We have used the PACS instrument on the Herschel Space Observatory to observe eight cataclysmic variables at 70 and 160 microns. Of these eight objects, only AM Her was detected. We have combined the Herschel results with ground-based, Spitzer, and WISE ... More
Searching For Rapid Orbital Decay of WASP-18bFeb 03 2017The WASP-18 system, with its massive and extremely close-in planet, WASP-18b (M$_{p}$ = 10.3M$_{J}$, a = 0.02 AU, P = 22.6 hours), is one of the best known exoplanet laboratories to directly measure Q', the modified tidal quality factor and proxy for ... More
How Many Universes Do There Need To Be?May 29 2006Mar 19 2007In the simplest cosmological models consistent with General Relativity, the total volume of the Universe is either finite or infinite, depending on whether or not the spatial curvature is positive. Current data suggest that the curvature is very close ... More
The random members of a $Π^0_1$ classNov 17 2016We examine several notions of randomness for elements in a given $\Pi^0_1$ class $\mathcal{P}$. Such an effectively closed subset $\mathcal{P}$ of $2^\omega$ may be viewed as the set of infinite paths through the tree $T_{\mathcal{P}}$ of extendible nodes ... More
Model-Robust Designs for Quantile RegressionMar 07 2014Sep 16 2014We give methods for the construction of designs for linear models, when the purpose of the investigation is the estimation of the conditional quantile function and the estimation method is quantile regression. The designs are robust against misspecified ... More
The Real Message in the SkyNov 15 2005A recent paper by Hsu & Zee (physics/0510102) suggests that if a Creator wanted to leave a message for us, and she wanted it to be decipherable to all sentient beings, then she would place it on the most cosmic of all billboards, the Cosmic Microwave ... More
An X-Ray Line from eXciting Dark MatterFeb 26 2014Mar 03 2014The eXciting Dark Matter (XDM) model was proposed as a mechanism to efficiently convert the kinetic energy (in sufficiently hot environments) of dark matter into e+e- pairs. The standard scenario invokes a doublet of nearly degenerate DM states, and a ... More
Magnetic Inelastic Dark Matter: Directional Signals Without a Directional DetectorNov 12 2010Apr 13 2011The magnetic inelastic dark matter (MiDM) model, in which dark matter inelastically scatters off nuclei through a magnetic dipole interaction, has previously been shown to reconcile the DAMA/LIBRA annual modulation signal with null results from other ... More
Memory beyond memory in heart beating: an efficient way to detect pathological conditionsJul 30 2001We study the long-range correlations of heartbeat fluctuations with the method of diffusion entropy. We show that this method of analysis yields a scaling parameter $\delta$ that apparently conflicts with the direct evaluation of the distribution of times ... More
Non-extensive diffusion entropy analysis: non-stationarity in teen birth phenomenaMay 24 2002A complex process is often a balance between non-stationary and stationary components. We show how the non-extensive Tsallis q-entropy indicator may be interpreted as a measure of non-stationarity in time series. This is done by applying the non-extensive ... More
Variational approach to dequantizationNov 08 2005Mar 28 2006We present a dequantization procedure based on a variational approach whereby quantum fluctuations latent in the quantum momentum are suppressed. This is done by adding generic local deformations to the quantum momentum operator which give rise to a deformed ... More
An Improved Process for Fabricating High-Mobility Organic Molecular Crystal Field-Effect TransistorsJun 21 2007In this paper we present an improved process for producing elastomer transistor stamps and high-mobility organic field-effect transistors (FETs) based on semiconducting acene molecular crystals. In particular, we have removed the need to use a silanized ... More
Quantum-classical correspondence via a deformed kinetic operatorApr 16 2005We propose an approach to the quantum-classical correspondence based on a deformation of the momentum and kinetic operators of quantum mechanics. Making use of the factorization method, we construct classical versions of the momentum and kinetic operators ... More
Preparation and detection of states with simultaneous spin alignment and molecular orientation in PbOJul 30 2008We are pursuing an experiment to measure the electric dipole moment of the electron using the molecule PbO. This measurement requires the ability to prepare quantum states with orientation of the molecular axis and, simultaneously, alignment of the electron ... More
The Fate of Sub-micron Circumplanetary Dust Grains II: Multipolar FieldsJun 05 2012We study the radial and vertical stability of dust grains launched with all charge-to-mass ratios at arbitrary distances from rotating planets with complex magnetic fields. We show that the aligned dipole magnetic field model analyzed by Jontof-Hutter ... More
On the origin of the Trojan asteroids: Effects of Jupiter's mass accretion and radial migrationJul 19 2000We present analytic and numerical results which illustrate the effects of Jupiter's accretion of nebular gas and the planet's radial migration on its Trojan companions. Initially, we approximate the system by the planar circular restricted three-body ... More
Four-Body Effects in Globular Cluster Black Hole CoalescenceFeb 15 2002In the high density cores of globular clusters, multibody interactions are expected to be common, with the result that black holes in binaries are hardened by interactions. It was shown by Sigurdsson & Hernquist (1993) and others that 10 solar mass black ... More
Secular Orbital Evolution of Compact Planet SystemsFeb 07 2013Oct 24 2013Recent observations have shown that at least some close-in exoplanets maintain eccentric orbits despite tidal circularization timescales that are typically shorter than stellar ages. We explore gravitational interactions with a distant planetary companion ... More
Production of Intermediate-Mass Black Holes in Globular ClustersJun 11 2001The discovery of numerous non-nuclear X-ray point sources with luminosities L>10^39 erg/s in several starburst galaxies has stimulated speculation about their nature and origin. The strong variability seen in several sources points to massive black holes ... More
The New Horizons and Hubble Space Telescope Search For Rings, Dust, and Debris in the Pluto-Charon SystemSep 23 2017We searched for dust or debris rings in the Pluto-Charon system before, during, and after the New Horizons encounter. Methodologies included searching for back-scattered light during the approach to Pluto (phase $\sim15^\circ$), in situ detection of impacting ... More
The Fate of Sub-Micron Circumplanetary Dust Grains I: Aligned Dipolar Magnetic FieldsJan 17 2012We study the stability of charged dust grains orbiting a planet and subject to gravity and the electromagnetic force. Our numerical models cover a broad range of launch distances from the planetary surface to beyond synchronous orbit, and the full range ... More
Implications of the PSR 1257+12 Planetary System for Isolated Millisecond PulsarsDec 02 2000The first extrasolar planets were discovered in 1992 around the millisecond pulsar PSR 1257+12. We show that recent developments in the study of accretion onto magnetized stars, plus the existence of the innermost, moon-sized planet in the PSR 1257+12 ... More
Is the 130 GeV Line Real? A Search for Systematics in the Fermi-LAT DataSep 20 2012Our recent claims of a Galactic center feature in Fermi-LAT data at approximately 130 GeV have prompted an avalanche of papers proposing explanations ranging from dark matter annihilation to exotic pulsar winds. Because of the importance of such interpretations ... More
Coupling M2-branes to background fieldsApr 28 2011We discuss some of the issues arising in trying to extend the ABJM action to include couplings to background fields. This is analogous to the Myers-Chern-Simons terms of the multiple Dp-brane action. We review and extend previous results to include terms ... More
A short proof that ``proper = unit''Nov 06 1998A short proof is given that the graphs with proper interval representations are the same as the graphs with unit interval representations.
Limits on the gravity wave contribution to microwave anisotropiesJan 05 1999Sep 13 1999We present limits on the fraction of large angle microwave anisotropies which could come from tensor perturbations. We use the COBE results as well as smaller scale CMB observations, measurements of galaxy correlations, abundances of galaxy clusters, ... More
The probability of a computable output from a random oracleDec 27 2016Apr 27 2017Consider a universal Turing machine that produces a partial or total function (or a binary stream), based on the answers to the binary queries that it makes during the computation. We study the probability that the machine will produce a computable function ... More
Random numbers as probabilities of machine behaviourMay 19 2016Jun 12 2017A fruitful way of obtaining meaningful, possibly concrete, algorithmically random numbers is to consider a potential behaviour of a Turing machine and its probability with respect to a measure (or semi-measure) on the input space of binary codes. For ... More
Inelastic Dark Matter and DAMA/LIBRA: An Experimentum CrucisJun 01 2009Sep 13 2010The DAMA/LIBRA collaboration has detected an annual modulation of the recoil rate in NaI crystals with the phase expected for WIMP scattering events. This signal is dramatically inconsistent with upper limits from other experiments for elastically scattering ... More
No evidence for anomalously low variance circles on the skyDec 06 2010Apr 07 2011In a recent paper, Gurzadyan & Penrose claim to have found directions on the sky centred on which are circles of anomalously low variance in the cosmic microwave background (CMB). These features are presented as evidence for a particular picture of the ... More
Observing the evolution of the CMBSep 26 2007Most cosmological parameters are expected to change significantly only on cosmological time scales, but given the large amount of information contained within the Cosmic Microwave Background (CMB) sky, we can expect that changes in the CMB should be observable ... More
Precision cosmology defeats void models for accelerationJul 21 2010Mar 24 2011The suggestion that we occupy a privileged position near the centre of a large, nonlinear, and nearly spherical void has recently attracted much attention as an alternative to dark energy. Putting aside the philosophical problems with this scenario, we ... More
Computational Theory of a splitting BEC using a Generalized Wannier basis I: Theory and StaticsAug 02 2010Nov 24 2010We investigate the behavior of a Bose-Einstein Condensate (BEC) under the influence of a central barrier as the particle number trends towards the thermodynamic limit. In order to perform these studies, we present a novel method which is tractable in ... More
Sharper Fermi LAT Images: instrument response functions for an improved event selectionJun 02 2014Sep 29 2014The Large Area Telescope on the Fermi Gamma-ray Space Telescope has a point spread function with large tails, consisting of events affected by tracker ineffiencies, inactive volumes, and hard scattering; these tails can make source confusion a limiting ... More
Gravity waves goodbyeApr 18 1999The detection of a stochastic background of long-wavelength gravitational waves (tensors) in the cosmic microwave background (CMB) anisotropy would be an invaluable probe of the high energy physics of the early universe. Unfortunately a combination of ... More
The Electron Injection Spectrum Determined by Anomalous Excesses in Cosmic Ray, Gamma Ray, and Microwave SignalsApr 07 2010Sep 13 2010Recent cosmic ray, gamma ray, and microwave signals observed by Fermi, PAMELA, and WMAP indicate an unexpected primary source of e+e- at 10-1000 GeV. We fit these data to "standard backgrounds" plus a new source, assumed to be a separable function of ... More
Error analysis of a partial pivoting method for structured matricesMay 05 2010Many matrices that arise in the solution of signal processing problems have a special displacement structure. For example, adaptive filtering and direction-of-arrival estimation yield matrices of Toeplitz type. A recent method of Gohberg, Kailath and ... More
Facing Non-Stationary Conditions with a New Indicator of Entropy Increase: The Cassandra AlgorithmNov 13 2001We address the problem of detecting non-stationary effects in time series (in particular fractal time series) by means of the Diffusion Entropy Method (DEM). This means that the experimental sequence under study, of size $N$, is explored with a window ... More
Scaling in Non-stationary Time Series II: Teen Birth PhenomenonJan 23 2003This paper is devoted to the problem of statistical mechanics raised by the analysis of an issue of sociological interest: the teen birth phenomenon. It is expected that these data are characterized by correlated fluctuations, reflecting the cooperative ... More
The GZK Bound and Strong Neutrino-Nucleon Interactions above 10^19eV: a Progress ReportAug 15 2000Cosmic ray events above 10^19 eV have posed a fundamental problem for more than thirty years. Recent measurements indicate that these events do not show the features predicted by the GZK bound. The events may, in addition, display angular correlations ... More
Geometry and Mechanics of Thin Growing BilayersSep 17 2015Oct 29 2015We investigate how thin sheets of arbitrary shapes morph under the isotropic in-plane expansion of their top surface, which may represent several stimuli such as nonuniform heating, local swelling and differential growth. Inspired by geometry, an analytical ... More
Extra dimensions and Strong Neutrino-Nucleon interactions above $10^{19}$ eV : Breaking the GZK BarrierJan 05 2000May 19 2000Cosmic ray events above $10^{20}$ eV are on the verge of confronting fundamental particle physics. The neutrino is the only candidate primary among established particles capable of crossing 100 Mpc intergalactic distances unimpeded. The magnitude of $\nu ... More
Little change in the sizes of the most massive galaxies since z = 1Jan 24 2011Recent reports suggest that elliptical galaxies have increased their size dramatically over the last ~8 Gyr. This result points to a major re-think of the processes dominating the latetime evolution of galaxies. In this paper we present the first estimates ... More
AlGaAs/GaAs single electron transistors fabricated without modulation dopingMar 01 2010We have fabricated quantum dot single electron transistors, based on AlGaAs/GaAs heterojunctions without modulation doping, which exhibit clear and stable Coulomb blockade oscillations. The temperature dependence of the Coulomb blockade peak lineshape ... More
Mass Inflation in Brans-Dicke gravityApr 17 2009A detailed non-linear analysis of the internal structure of spherical, charged black holes that are accreting scalar matter is performed in the framework of the Brans-Dicke theory of gravity. We choose the lowest value of the Brans-Dicke parameter that ... More
Mass inflation in a D dimensional Reissner-Nordstrom black hole: a hierarchy of particle accelerators ?May 23 2011We study the geometry inside the event horizon of perturbed D dimensional Reissner-Nordstrom-(A)dS type black holes showing that, similarly to the four dimensional case, mass inflation also occurs for D>4. First, using the homogeneous approximation, we ... More
Piezoelectric rotator for studying quantum effects in semiconductor nanostructures at high magnetic fields and low temperaturesSep 14 2010We report the design and development of a piezoelectric sample rotation system, and its integration into an Oxford Instruments Kelvinox 100 dilution refrigerator, for orientation-dependent studies of quantum transport in semiconductor nanodevices at millikelvin ... More
A nondiagrammatic description of the Connes-Kreimer Hopf algebraMar 13 2012We demonstrate that the fundamental algebraic structure underlying the Connes-Kreimer Hopf algebra -- the insertion pre-Lie structure on graphs -- corresponds directly to the canonical pre-Lie structure of polynomial vector fields. Using this fact, we ... More
First Measurement of Neutrino Interactions in MicroBooNENov 02 2016The MicroBooNE detector has recently completed its first year of neutrino beam data-taking in the Booster Neutrino Beam at Fermilab, having collected approximately half of its intended data ($3.4\times10^{20}$ of $6.6\times10^{20}$ protons on target). ... More
LArIAT: Worlds First Pion-Argon Cross-SectionNov 02 2016The LArIAT experiment has performed the world's first measurement of the total charged-current pion cross-section on an argon target, using the repurposed ArgoNeuT detector in the Fermilab test beam. Presented here are the results of that measurement, ... More
Classes on the moduli space of Riemann surfaces through a noncommutative Batalin-Vilkovisky formalismApr 22 2011Using the machinery of the Batalin-Vilkovisky formalism, we construct cohomology classes on compactifications of the moduli space of Riemann surfaces from the data of a contractible differential graded Frobenius algebra. We describe how evaluating these ... More
A Poincaré-Birkhoff-Witt Theorem for profinite pronilpotent Lie algebrasApr 01 2018We prove a version of the Poincar\'e-Birkhoff-Witt Theorem for profinite pronilpotent Lie algebras in which their symmetric and universal enveloping algebras are replaced with appropriate formal analogues and discuss some immediate corollaries of this ... More
Asymptotic parameterization in inverse limit spaces of dendritesJun 13 2012In this paper, we study asymptotic behavior arising in inverse limit spaces of dendrites. In particular, the inverse limit is constructed with a single unimodal bonding map, for which points have unique itineraries and the critical point is periodic. ... More
Finitary Group Cohomology and Eilenberg-Mac Lane SpacesMar 17 2008Nov 08 2008We say that a group G has cohomology almost everywhere finitary if and only if the nth cohomology functors of G commute with filtered colimits for all sufficiently large n. In this paper, we show that if G is a group in Kropholler's class LHF with cohomology ... More
A super-analogue of Kontsevich's theorem on graph homologyOct 18 2005In this paper we will prove a super-analogue of a well-known result by Kontsevich which states that the homology of a certain complex which is generated by isomorphism classes of oriented graphs can be calculated as the Lie algebra homology of an infinite-dimensional ... More
On the extension of a TCFT to the boundary of the moduli spaceFeb 13 2010The purpose of this paper is to describe an analogue of a construction of Costello in the context of finite-dimensional differential graded Frobenius algebras which produces closed forms on the decorated moduli space of Riemann surfaces. We show that ... More
Pick interpolation in several variablesOct 03 2011Oct 05 2011We investigate the Pick problem for the polydisk and unit ball using dual algebra techniques. Some factorization results for Bergman spaces are used to describe a Pick theorem for any bounded region in $\mathbb{C}^d$.
Semi-Supervised Translation with MMD NetworksOct 28 2018This work aims to improve semi-supervised learning in a neural network architecture by introducing a hybrid supervised and unsupervised cost function. The unsupervised component is trained using a differentiable estimator of the Maximum Mean Discrepancy ... More
Classes on compactifications of the moduli space of curves through solutions to the quantum master equationJul 14 2008Apr 28 2009In this paper we describe a construction which produces classes in a compactification of the moduli space of curves. This construction extends a construction of Kontsevich which produces classes in the open moduli space from the initial data of a cyclic ... More
On the classification of Moore algebras and their deformationsApr 22 2003In this paper we will study deformations of A-infinity algebras. We will also answer questions relating to Moore algebras which are one of the simplest nontrivial examples of an A-infinity algebra. We will compute the Hochschild cohomology of odd Moore ... More
Growth of Intermediate-Mass Black Holes in Globular ClustersFeb 23 2004We present results of numerical simulations of sequences of binary-single scattering events of black holes in dense stellar environments. The simulations cover a wide range of mass ratios from equal mass objects to 1000:10:10 solar masses and compare ... More
Fast Simulation of Facilitated Spin ModelsOct 13 2005Dec 21 2005We show how to apply the absorbing Markov chain Monte Carlo algorithm of Novotny to simulate kinetically constrained models of glasses. We consider in detail one-spin facilitated models, such as the East model and its generalizations to arbitrary dimensions. ... More
Yarkovsky-Driven Spreading of the Eureka Family of Mars TrojansDec 04 2014Out of nine known stable Mars Trojans, seven appear to be members of an orbital grouping including the largest Trojan, Eureka. In order to test if this could be a genetic family, we simulated the long term evolution of a tight orbital cluster centered ... More
Long-Term Stability of Horseshoe OrbitsJun 08 2012Aug 24 2012Unlike Trojans, horseshoe coorbitals are not generally considered to be long-term stable (Dermott and Murray, 1981; Murray and Dermott, 1999). As the lifetime of Earth's and Venus's horseshoe coorbitals is expected to be about a Gyr, we investigated the ... More
An obstruction based approach to the Kochen-Specker theoremDec 03 1999In [1] it was shown that the Kochen Specker theorem can be written in terms of the non-existence of global elements of a certain varying set over the partially ordered set of boolean subalgebras of projection operators on some Hilbert space. In this paper, ... More
Noncommutative geometry and compactifications of the moduli space of curvesOct 25 2007In this paper we show that the homology of a certain natural compactification of the moduli space, introduced by Kontsevich in his study of Witten's conjectures, can be described completely algebraically as the homology of a certain differential graded ... More
Finitary Group Cohomology and Group Actions on SpheresMar 17 2008We show that if G is an infinitely generated locally (polycyclic-by-finite) group with cohomology almost everywhere finitary, then every finite subgroup of G acts freely and orthogonally on some sphere.
Stripe orientation in an anisotropic t-J modelFeb 28 2001The tilt pattern of the CuO_6 octahedra in the LTT phase of the cuprate superconductors leads to planar anisotropies for the exchange coupling and hopping integrals. Here, we show that these anisotropies provide a possible structural mechanism for the ... More
Inference of Unresolved Point Sources At High Galactic Latitudes Using Probabilistic CatalogsJul 15 2016Mar 09 2017Detection of point sources in images is a fundamental operation in astrophysics, and is crucial for constraining population models of the underlying point sources or characterizing the background emission. Standard techniques fall short in the crowded-field ... More
Self-Assembly of Patchy Particles into Polymer Chains: A Parameter-Free Comparison between Wertheim Theory and Monte Carlo SimulationJan 22 2007We numerically study a simple fluid composed of particles having a hard-core repulsion, complemented by two short-ranged attractive (sticky) spots at the particle poles, which provides a simple model for equilibrium polymerization of linear chains. The ... More
Large deviation principles for hypersingular Riesz gasesFeb 09 2017Nov 07 2017We study $N$-particle systems in R^d whose interactions are governed by a hypersingular Riesz potential $|x-y|^{-s}$, $s>d$, and subject to an external field. We provide both macroscopic results as well as microscopic results in the limit as $N\to \infty$ ... More
Curvature-Driven Morphing of Non-Euclidean ShellsNov 20 2016Jun 06 2017We investigate how thin structures change their shape in response to non-mechanical stimuli that can be interpreted as variations in the structure's natural curvature. Starting from the theory of non-Euclidean plates and shells, we derive an effective ... More
Condition number estimates for matrices arising in NURBS based isogeometric discretizations of elliptic partial differential equationsJun 26 2014We derive bounds for the minimum and maximum eigenvalues and the spectral condition number of matrices for isogeometric discretizations of elliptic partial differential equations in an open, bounded, simply connected Lipschitz domain $\Omega\subset \mathbb{R}^d$, ... More
A comparative study of fairness-enhancing interventions in machine learningFeb 13 2018Computers are increasingly used to make decisions that have significant impact in people's lives. Often, these predictions can affect different population subgroups disproportionately. As a result, the issue of fairness has received much recent interest, ... More
Optimizing the Determination of the Neutrino Mixing Angle $θ_{13}$ from Reactor DataJul 12 2013Jan 17 2014The technical breakthroughs of multiple detectors developed by Daya Bay and RENO collaborations have gotten great attention. Yet the optimal determination of neutrino mixing parameters from reactor data depends on the statistical method and demands equal ... More
Filler-Induced Composition Waves in Phase-Separating Polymer BlendsJun 08 1999The influence of immobile filler particles (spheres, fibers, platelets) on polymer blend phase separation is investigated computationally using a generalization of the Cahn-Hilliard-Cook (CHC) model. Simulation shows that the selective affinity of one ... More
Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?May 29 2010Oct 18 2010Data from the Fermi-LAT reveal two large gamma-ray bubbles, extending 50 degrees above and below the Galactic center, with a width of about 40 degrees in longitude. The gamma-ray emission associated with these bubbles has a significantly harder spectrum ... More
The PAMELA Positron Excess from Annihilations into a Light BosonOct 30 2008Apr 30 2009Recently published results from the PAMELA experiment have shown conclusive evidence for an excess of positrons at high (~ 10 - 100 GeV) energies, confirming earlier indications from HEAT and AMS-01. Such a signal is generally expected from dark matter ... More
Static bistability of spherical capsApr 11 2018May 18 2018Depending on its geometry, a spherical shell may exist in one of two stable states without the application of any external force: there are two `self-equilibrated' states, one natural and the other inside out (or `everted'). Though this is familiar from ... More
A Sharp Balian-Low Uncertainty Principle for Shift-Invariant SpacesOct 16 2015A sharp version of the Balian-Low theorem is proven for the generators of finitely generated shift-invariant spaces. If generators $\{f_k\}_{k=1}^K \subset L^2(\mathbb{R}^d)$ are translated along a lattice to form a frame or Riesz basis for a shift-invariant ... More
Searching for Dark Matter in the CMB: A Compact Parameterization of Energy Injection from New PhysicsSep 28 2011High-precision measurements of the temperature and polarization anisotropies of the cosmic microwave background radiation have been previously employed to set robust constraints on dark matter annihilation during recombination. In this work we improve ... More
Parity Edge-Coloring of GraphsFeb 15 2006In a graph whose edges are colored, a parity walk is a walk that uses each color an even number of times. The parity edge chromatic number p(G) of a graph G is the least k so that there is a coloring of E(G) using k colors that does not contain a parity ... More
New lower bound for the Hilbert number in piecewise quadratic differential systemsSep 10 2018We study the number of limit cycles bifurcating from a piecewise quadratic system. All the differential systems considered are piecewise in two zones separated by a straight line. We prove the existence of 16 crossing limit cycles in this class of systems. ... More
Unconstrained polarization (Chebyshev) problems: basic properties and Riesz kernel asymptoticsFeb 22 2019Mar 23 2019We introduce and study the unconstrained polarization (or Chebyshev) problem which requires to find an $N$-point configuration that maximizes the minimum value of its potential over a set $A$ in $p$-dimensional Euclidean space. This problem is compared ... More
Inverse Bernstein inequalities and min-max-min problems on the unit circleJul 15 2013We give a short and elementary proof of an inverse Bernstein-type inequality found by S. Khrushchev for the derivative of a polynomial having all its zeros on the unit circle. The inequality is used to show that equally-spaced points solve a min-max-min ... More