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Earth: Atmospheric Evolution of a Habitable PlanetMar 15 2018Our present-day atmosphere is often used as an analog for potentially habitable exoplanets, but Earth's atmosphere has changed dramatically throughout its 4.5 billion year history. For example, molecular oxygen is abundant in the atmosphere today but ... More

A limited habitable zone for complex lifeFeb 13 2019The habitable zone (HZ) is defined as the range of distances from a host star within which liquid water, a key requirement for life, may exist at a planet's surface. Substantially more CO2 than present in Earth's modern atmosphere is required to maintain ... More

Rethinking CO Antibiosignatures in the Search for Life Beyond the Solar SystemMar 18 2019Some atmospheric gases have been proposed as counter indicators to the presence of life on an exoplanet if remotely detectable at sufficient abundance (i.e., antibiosignatures), informing the search for biosignatures and potentially fingerprinting uninhabited ... More

Disequilibrium biosignatures over Earth history and implications for detecting exoplanet lifeJan 24 2018Chemical disequilibrium in planetary atmospheres has been proposed as a generalized method for detecting life on exoplanets through remote spectroscopy. Among solar system planets with substantial atmospheres, the modern Earth has the largest thermodynamic ... More

The remote detectability of Earth's biosphere through time and the importance of UV capability for characterizing habitable exoplanetsMar 13 2019Thousands of planets beyond our solar system have been discovered to date, dozens of which are rocky in composition and are orbiting within the circumstellar habitable zone of their host star. The next frontier in life detection beyond our solar system ... More

Learning Unitary Operators with Help From u(n)Jul 17 2016A major challenge in the training of recurrent neural networks is the so-called vanishing or exploding gradient problem. The use of a norm-preserving transition operator can address this issue, but parametrization is challenging. In this work we focus ... More

How Gas Accretion Feeds Galactic DisksMar 15 2019Numerous observations indicate that galaxies need a continuous gas supply to fuel star formation and explain the star formation history. However, direct observational evidence of gas accretion remains rare. Using the EAGLE cosmological hydrodynamic simulation ... More

Predictive Hierarchical Clustering: Learning clusters of CPT codes for improving surgical outcomesApr 24 2016Aug 01 2017We develop a novel algorithm, Predictive Hierarchical Clustering (PHC), for agglomerative hierarchical clustering of current procedural terminology (CPT) codes. Our predictive hierarchical clustering aims to cluster subgroups, not individual observations, ... More

A Statistical Comparative Planetology Approach to Maximize the Scientific Return of Future Exoplanet Characterization EffortsMar 12 2019Provided that sufficient resources are deployed, we can look forward to an extraordinary future in which we will characterize potentially habitable planets. Until now, we have had to base interpretations of observations on habitability hypotheses that ... More

False negatives for remote life detection on ocean-bearing planets: Lessons from the early EarthFeb 03 2017Ocean-atmosphere chemistry on Earth has undergone dramatic evolutionary changes through its long history, with potentially significant ramifications for the emergence and long-term stability of atmospheric biosignatures. Though a great deal of work has ... More

Magnetically-controlled velocity selection in a cold atom sample using stimulated Raman transitionsJan 03 2008We observe velocity-selective two-photon resonances in a cold atom cloud in the presence of a magnetic field. We use these resonances to demonstrate a simple magnetometer with sub-mG resolution. The technique is particularly useful for zeroing the magnetic ... More

Softening of Granular Packings with Dynamic ForcingJun 17 2014We perform numerical simulations of a two-dimensional bidisperse granular packing subjected to both a static confining pressure and a sinusoidal dynamic forcing applied by a wall on one edge of the packing. We measure the response experienced by a wall ... More

Ultrafast entangling gates between nuclear spins using photo-excited triplet statesJan 23 2012The representation of information within the spins of electrons and nuclei has been powerful in the ongoing development of quantum computers. Although nuclear spins are advantageous as quantum bits (qubits) due to their long coherence lifetimes (exceeding ... More

Improving Clinical Predictions through Unsupervised Time Series Representation LearningDec 02 2018In this work, we investigate unsupervised representation learning on medical time series, which bears the promise of leveraging copious amounts of existing unlabeled data in order to eventually assist clinical decision making. By evaluating on the prediction ... More

Analyzing Worms and Network Traffic using CompressionApr 12 2005Internet worms have become a widespread threat to system and network operations. In order to fight them more efficiently, it is necessary to analyze newly discovered worms and attack patterns. This paper shows how techniques based on Kolmogorov Complexity ... More

The second laws of quantum thermodynamicsMay 22 2013Sep 25 2014The second law of thermodynamics tells us which state transformations are so statistically unlikely that they are effectively forbidden. Its original formulation, due to Clausius, states that "Heat can never pass from a colder to a warmer body without ... More

Expanding cosmological civilizations on the back of an envelopeMay 15 2018We present a simplified description of expansionistic life in the standard relativistic cosmology. The resulting model is exactly integrable, yielding a simple set of predictive formulas. This allows one to quickly propose new scenarios for the life appearance ... More

Estimates for the number of visible galaxy-spanning civilizations and the cosmological expansion of lifeJul 21 2015Apr 22 2016If advanced civilizations appear in the universe with an ability and desire to expand, the entire universe can become saturated with life on a short timescale, even if such expanders appear rarely. Our presence in an apparently untouched Milky Way thus ... More

Rigorous results for the distribution of money on connected graphsJan 01 2018This paper is concerned with general spatially explicit versions of three stochastic models for the dynamics of money that have been introduced and studied numerically by statistical physicists: the uniform reshuffling model, the immediate exchange model ... More

Tautological pairings on moduli spaces of curvesFeb 14 2009Feb 26 2009We discuss analogs of Faber's conjecture for two nested sequences of partial compactifications of the moduli space of smooth curves. We show that their tautological rings are one-dimensional in top degree but do not satisfy Poincare duality.

Atmospheric Seasonality as an Exoplanet BiosignatureJun 12 2018Current investigations of exoplanet biosignatures have focused on static evidence of life, such as the presence of biogenic gases like O2 or CH4. However, the expected diversity of terrestrial planet atmospheres and the likelihood of both false positives ... More

Enhanced star formation in both disks and ram pressure stripped tails of GASP jellyfish galaxiesOct 11 2018Exploiting the data from the GAs Stripping Phenomena in galaxies with MUSE (GASP) program, we compare the integrated Star Formation Rate- Mass relation (SFR-M_ast) relation of 42 cluster galaxies undergoing ram pressure stripping ("stripping galaxies") ... More

Predicting evolutionary site variability from structure in viral proteins: buriedness, packing, flexibility, and designApr 29 2014Jul 21 2014Several recent works have shown that protein structure can predict site-specific evolutionary sequence variation. In particular, sites that are buried and/or have many contacts with other sites in a structure have been shown to evolve more slowly, on ... More

Radial Basis Function (RBF)-based Parametric Models for Closed and Open Curves within the Method of Regularized StokesletsFeb 27 2015The method of regularized Stokeslets (MRS) is a numerical approach using regularized fundamental solutions to compute the flow due to an object in a viscous fluid where inertial effects can be neglected. The elastic object is represented as a Lagrangian ... More

ARPES Study of X-Point Band Overlaps in LaB$_6$ and SmB$_6$ - Contrast to SrB$_6$ and EuB$_6$Jul 10 2001In contrast to our recent finding of an X-point band gap in divalent hexaborides, we report here that angle resolved photoemission spectroscopy (ARPES) data shows that the gap is absent for trivalent LaB$_6$ and is absent or nearly so for mixed valent ... More

Bulk Band Gaps in Divalent HexaboridesJul 20 2001Aug 09 2002Complementary angle-resolved photoemission and bulk-sensitive k-resolved resonant inelastic x-ray scattering of divalent hexaborides reveal a >1 eV X-point gap between the valence and conduction bands, in contradiction to the band overlap assumed in several ... More

Monte Carlo Study of the Critical Behavior of Random Bond Potts ModelsMar 04 1999Aug 30 1999We present results of Monte Carlo simulations of random bond Potts models in two dimensions, for different numbers of Potts states, q. We introduce a simple scheme which yields continuous self-dual distributions of the interactions. As expected, we find ... More

Finite Temperature Ordering in the Three-Dimensional Gauge GlassDec 15 1999We present results of Monte Carlo simulations of the gauge glass model in three dimensions using exchange Monte Carlo. We show for the first time clear evidence of the vortex glass ordered phase at finite temperature. Using finite size scaling we obtain ... More

Malware Epidemics Effects in a Lanchester Conflict ModelNov 05 2018For developing a better comprehension of the consequences of cyber-attacks, the paper examines the influence of system infections with self-replicating malware on the outcome of kinetic combat. The situation is represented as a system-dynamics model consisting ... More

Equality of Schur and skew Schur functionsOct 04 2004Jun 22 2007We determine the precise conditions under which any skew Schur function is equal to a Schur function over both infinitely and finitely many variables.

Rigorous results for the distribution of money on connected graphs (models with debts)Dec 26 2018In this paper, we continue our analysis of spatial versions of agent-based models for the dynamics of money that have been introduced in the statistical physics literature, focusing on two models with debts. Both models consist of systems of economical ... More

Asynchronous reference frame agreement in a quantum networkMay 11 2015Mar 30 2016An efficient implementation of many multiparty protocols for quantum networks requires that all the nodes in the network share a common reference frame. Establishing such a reference frame from scratch is especially challenging in an asynchronous network ... More

Dependence of a quantum mechanical system on its own initial state and the initial state of the environment it interacts withNov 14 2011Jan 03 2013We present a unifying framework to the understanding of when and how quantum mechanical systems become independent of their initial conditions and adapt macroscopic properties (like temperature) of the environment.By viewing this problem from an quantum ... More

The uncertainty principle determines the non-locality of quantum mechanicsApr 14 2010Nov 19 2010Two central concepts of quantum mechanics are Heisenberg's uncertainty principle, and a subtle form of non-locality that Einstein famously called ``spooky action at a distance''. These two fundamental features have thus far been distinct concepts. Here ... More

Transforming graph states using single-qubit operationsMay 14 2018May 15 2018Stabilizer states form an important class of states in quantum information, and are of central importance in quantum error correction. Here, we provide an algorithm for deciding whether one stabilizer (target) state can be obtained from another stabilizer ... More

Chain lengths in the type $B$ Tamari latticeSep 18 2018We find the largest union of two chains in the type $B$ Tamari lattice by generalizing the techniques used for the classical (type $A$) Tamari lattice with a description of the type $B$ case due to Hugh Thomas.

A unified view on Hardy's paradox and the CHSH inequalityJul 09 2014Bell's inequality fundamentally changed our understanding of quantum mechanics. Bell's insight that non-local correlations between quantum systems cannot be explained classically can be verified experimentally, and has numerous applications in modern ... More

Quantum Anonymous TransmissionsSep 28 2004Aug 15 2005We consider the problem of hiding sender and receiver of classical and quantum bits (qubits), even if all physical transmissions can be monitored. We present a quantum protocol for sending and receiving classical bits anonymously, which is completely ... More

Hagedorn wavepackets in time-frequency and phase spaceMar 21 2013Mar 12 2014The Hermite functions are an orthonormalbasis of the space of square integrable functions with favourable approximation properties. Allowing for a flexible localization in position and momentum, the Hagedorn wavepackets generalize the Hermite functions ... More

The role of cooperation in spatially explicit economical systemsApr 22 2017This paper is concerned with a model in econophysics, the subfield of statistical physics that applies concepts from traditional physics to economics. In our model, economical agents are represented by the vertices of a connected graph and are characterized ... More

Automated testing of optical fibres: towards the design of the Maunakea Spectroscopic Explorer Fibre Transmission SystemJul 20 2018We present the results of an automated fibre optic test bench constructed at the University of Victoria as part of the Maunakea Spectroscopic Explorer (MSE) Fibre Transmission System (FiTS). In preparation for MSE-FiTS, we have begun characterizing the ... More

Chromatic classical symmetric functionsApr 13 2016May 26 2017In this note we classify when a skew Schur function is a positive linear combination of power sum symmetric functions. We then use this to determine precisely when any scalar multiple of a skew Schur function is the chromatic symmetric function of some ... More

Swimming Speeds of Waving Cylindrical Tails in Viscous Fluids with ResistanceJun 11 2015Dec 24 2015Many microorganisms swim in a highly heterogeneous environment with obstacles such as fibers or polymers. To better understand how this environment affects microorganism swimming, we study propulsion of a cylinder or filament in a fluid with a sparse, ... More

Probability, unitarity, and realism in generally covariant quantum informationAug 27 2007Feb 13 2008The formalism of covariant quantum theory, introduced by Reisenberger and Rovelli, casts the description of quantum states and evolution into a framework compatable with the principles of general relativity. The leap to this covariant formalism, however, ... More

Entanglement between the future and past in the quantum vacuumMar 03 2010We note that massless fields within the future and past light cone may be quantized as independent systems. We show that the vacuum is an entangled state of these systems, exactly mirroring the known entanglement between the spacelike separated Rindler ... More

On the $1/3-2/3$ ConjectureJun 15 2017Jan 31 2018Let $(P,\leq)$ be a finite poset (partially ordered set), where $P$ has cardinality $n$. Consider linear extensions of $P$ as permutations $x_1x_2\cdots x_n$ in one-line notation. For distinct elements $x,y\in P$, we define $\mathbb{P}(x\prec y)$ to be ... More

The Importance of UV Capabilities for Identifying Inhabited Exoplanets with Next Generation Space TelescopesJan 09 2018The strongest remotely detectable signature of life on our planet today is the photosynthetically produced oxygen (O2) in our atmosphere. However, recent studies of Earth's geochemical proxy record suggest that for all but the last ~500 million years, ... More

Chromatic bases for symmetric functionsAug 31 2015Aug 29 2016In this note we obtain numerous new bases for the algebra of symmetric functions whose generators are chromatic symmetric functions. More precisely, if $\{ G_ k \}_{k\geq 1}$ is a set of connected graphs such that $G_k$ has $k$ vertices for each $k$, ... More

Permuted composition tableaux, 0-Hecke algebra and labeled binary treesDec 13 2017Aug 28 2018We introduce a generalization of semistandard composition tableaux called permuted composition tableaux. These tableaux are intimately related to permuted basement semistandard augmented fillings studied by Haglund, Mason and Remmel. Our primary motivation ... More

Necessary conditions for Schur-maximalityNov 27 2017May 08 2018McNamara and Pylyavskyy conjectured precisely which connected skew shapes are maximal in the Schur-positivity order, which says that $B\leq _s A$ if $s_A-s_B$ is Schur-positive. Towards this, McNamara and van Willigenburg proved that it suffices to study ... More

On (almost) extreme components in Kronecker products of characters of the symmetric groupsMay 16 2011Apr 12 2013Using a recursion formula due to Dvir, we obtain information on maximal and almost maximal components in Kronecker products of characters of the symmetric groups. This is applied to confirm a conjecture made by Bessenrodt and Kleshchev in 1999, which ... More

A photonic platform for donor spin qubits in siliconJun 10 2016Donor impurity spins in silicon-28 are highly competitive qubits for upcoming solid-state quantum technologies, yet a proven scalable strategy for multi-qubit devices remains conspicuously absent. These CMOS-compatible, atomically identical qubits offer ... More

New Perspective on Galaxy Outflows From the First Detection of Both Intrinsic and Traverse Metal-Line AbsorptionJul 15 2014We present the first observation of a galaxy (z=0.2) that exhibits metal-line absorption back-illuminated by the galaxy ("down-the-barrel") and transversely by a background quasar at a projected distance of 58 kpc. Both absorption systems, traced by MgII, ... More

Spectral Filtering of Interpolant Observables for a Discrete-in-time Downscaling Data Assimilation AlgorithmSep 23 2018Oct 01 2018We describe a spectrally-filtered discrete-in-time downscaling data assimilation algorithm and prove, in the context of the two-dimensional Navier--Stokes equations, that this algorithm works for a general class of interpolants, such as those based on ... More

Towards a combinatorial classification of skew Schur functionsAug 17 2006Dec 10 2008We present a single operation for constructing skew diagrams whose corresponding skew Schur functions are equal. This combinatorial operation naturally generalises and unifies all results of this type to date. Moreover, our operation suggests a closely ... More

Quasisymmetric and noncommutative skew Pieri rulesDec 15 2015May 29 2018In this note we derive skew Pieri rules in the spirit of Assaf-McNamara for skew quasisymmetric Schur functions using the Hopf algebraic techniques of Lam-Lauve-Sottile, and recover the original rules of Assaf-McNamara as a special case. We then apply ... More

Multiplicity free Schur, skew Schur, and quasisymmetric Schur functionsMay 21 2011Mar 02 2012In this paper we classify all Schur functions and skew Schur functions that are multiplicity free when expanded in the basis of fundamental quasisymmetric functions, termed F-multiplicity free. Combinatorially, this is equivalent to classifying all skew ... More

Improved Lower Bounds for Locally Decodable Codes and Private Information RetrievalMar 19 2004May 19 2005We prove new lower bounds for locally decodable codes and private information retrieval. We show that a 2-query LDC encoding n-bit strings over an l-bit alphabet, where the decoder only uses b bits of each queried position of the codeword, needs code ... More

Entropic uncertainty relations and locking: tight bounds for mutually unbiased basesJun 29 2006Mar 21 2007We prove tight entropic uncertainty relations for a large number of mutually unbiased measurements. In particular, we show that a bound derived from the result by Maassen and Uffink for 2 such measurements can in fact be tight for up to sqrt{d} measurements ... More

Lollipop and lariat symmetric functionsFeb 22 2017May 03 2018We compute an explicit $e$-positive formula for the chromatic symmetric function of a lollipop graph, $L_{m,n}$. From here we deduce that there exist countably infinite distinct $e$-positive, and hence Schur-positive, bases of the algebra of symmetric ... More

Convergence of SDP hierarchies for polynomial optimization on the hypersphereOct 18 2012Jun 22 2013We show how to bound the accuracy of a family of semi-definite programming relaxations for the problem of polynomial optimization on the hypersphere. Our method is inspired by a set of results from quantum information known as quantum de Finetti theorems. ... More

Critical depinning force and vortex lattice order in disordered superconductorsOct 07 2000We simulate the ordering of vortices and its effects on the critical current in superconductors with varied vortex-vortex interaction strength and varied pinning strengths for a two-dimensional system. For strong pinning the vortex lattice is always disordered ... More

Almost bi-Lipschitz embeddings and almost homogeneous setsMay 03 2007This paper is concerned with embeddings of homogeneous spaces into Euclidean spaces. We show that any homogeneous metric space can be embedded into a Hilbert space using an almost bi-Lipschitz mapping (bi-Lipschitz to within logarithmic corrections). ... More

Microlocal analysis on wonderful varieties. Regularized traces and global charactersMar 07 2014Nov 09 2015Let $\mathbf{G}$ be a connected reductive complex algebraic group with split real form $(G,\sigma)$. Consider a strict wonderful $\mathbf{G}$-variety $\bf{X}$ equipped with its $\sigma$-equivariant real structure, and let $X$ be the corresponding real ... More

Maximal supports and Schur-positivity among connected skew shapesJul 21 2011Mar 01 2012The Schur-positivity order on skew shapes is defined by B \leq A if the difference s_A - s_B is Schur-positive. It is an open problem to determine those connected skew shapes that are maximal with respect to this ordering. A strong necessary condition ... More

The Factory and the Beehive III: PTFEB132.707+19.810, a Low-Mass Eclipsing Binary in Praesepe Observed by PTF and K2Jun 28 2017Theoretical models of stars constitute a fundamental bedrock upon which much of astrophysics is built, but large swaths of model parameter space remain uncalibrated by observations. The best calibrators are eclipsing binaries in clusters, allowing measurement ... More

Responses to remixing on a social media sharing websiteJul 05 2015In this paper we describe the ways participants of the Scratch online community, primarily young people, engage in remixing of each others' shared animations, games, and interactive projects. In particular, we try to answer the following questions: How ... More

Two Perspectives on the Twist of DNAMar 09 2009Because of the double-helical structure of DNA, in which two strands of complementary nucleotides intertwine around each other, a covalently closed DNA molecule with no interruptions in either strand can be viewed as two interlocked single-stranded rings. ... More

Bayesian Dyadic Trees and Histograms for RegressionJul 31 2017Nov 28 2017Many machine learning tools for regression are based on recursive partitioning of the covariate space into smaller regions, where the regression function can be estimated locally. Among these, regression trees and their ensembles have demonstrated impressive ... More

Rethinking the Generational Gap in Online News Use: An Infrastructural PerspectiveApr 04 2017Our study investigates the role of infrastructures in shaping online news usage by contrasting use patterns of two social groups,millennials and boomers,that are specifically located in news infrastructures. Typically based on self reported data, popular ... More

An optimal lower curvature bound for convex hypersurfaces in Riemannian manifoldsMar 23 2013It is proved that a convex hypersurface in a Riemannian manifold of sectional curvature at least k is an Alexandrov's space of curvature at least k. This theorem provides an optimal lower curvature bound for an older theorem of Buyalo.

Modules of the 0-Hecke algebra and quasisymmetric Schur functionsMar 06 2014Aug 20 2015We begin by deriving an action of the 0-Hecke algebra on standard reverse composition tableaux and use it to discover 0-Hecke modules whose quasisymmetric characteristics are the natural refinements of Schur functions known as quasisymmetric Schur functions. ... More

KL to pi0 e+ e- and KL to pi0 mu+ mu- : A binary star on the stage of flavor physicsJun 07 2006Aug 29 2006A systematic analysis of New Physics impacts on the rare decays KL to pi0 l+ l- is performed. Thanks to their different sensitivities to flavor-changing local effective interactions, these two modes could provide valuable information on the nature of ... More

Cryptography from Noisy StorageNov 19 2007Jun 20 2008We show how to implement cryptographic primitives based on the realistic assumption that quantum storage of qubits is noisy. We thereby consider individual-storage attacks, i.e. the dishonest party attempts to store each incoming qubit separately. Our ... More

Fully device independent Conference Key AgreementAug 02 2017We present the first security analysis of conference key agreement (CKA) in the most adversarial model of device independence (DI). Our protocol can be implemented by any experimental setup that is capable of performing Bell tests (specifically, the Mermin-Ardehali-Belinskii-Klyshko ... More

Representations of the multi-qubit Clifford groupSep 26 2016May 28 2018The Clifford group is a fundamental structure in quantum information with a wide variety of applications. We discuss the tensor representations of the $q$-qubit Clifford group, which is defined as the normalizer of the $q$-qubit Pauli group in $U(2^q)$. ... More

Equivalence of wave-particle duality to entropic uncertaintyMar 19 2014Sep 16 2014Interferometers capture a basic mystery of quantum mechanics: a single particle can exhibit wave behavior, yet that wave behavior disappears when one tries to determine the particle's path inside the interferometer. This idea has been formulated quantitively ... More

Entanglement sampling and applicationsMay 06 2013Jun 15 2015A natural measure for the amount of quantum information that a physical system E holds about another system A = A_1,...,A_n is given by the min-entropy Hmin(A|E). Specifically, the min-entropy measures the amount of entanglement between E and A, and is ... More

Schur and $e$-positivity of trees and cut verticesJan 08 2019We prove that the chromatic symmetric function of any $n$-vertex tree containing a vertex of degree $d\geq \log _2n +1$ is not $e$-positive, that is, not a positive linear combination of elementary symmetric functions. Generalizing this, we also prove ... More

The History of Star Formation in Galaxy Disks in the Local Volume as Measured by the ACS Nearby Galaxy Survey TreasuryMay 12 2011We present a measurement of the age distribution of stars residing in spiral disks and dwarf galaxies. We derive a complete star formation history of the ~140 Mpc^3 covered by the volume-limited sample of galaxies in the Advanced Camera for Surveys (ACS) ... More

How to transform graph states using single-qubit operations: computational complexity and algorithmsMay 14 2018May 15 2018Graph states are ubiquitous in quantum information with diverse applications ranging from quantum network protocols to measurement based quantum computing. Here we consider the question whether one graph (source) state can be transformed into another ... More

Entropic uncertainty and measurement reversibilityNov 01 2015May 31 2016The entropic uncertainty relation with quantum side information (EUR-QSI) from [Berta et al., Nat. Phys. 6, 659 (2010)] is a unifying principle relating two distinctive features of quantum mechanics: quantum uncertainty due to measurement incompatibility, ... More

Unconditional security from noisy quantum storageJun 05 2009Sep 08 2011We consider the implementation of two-party cryptographic primitives based on the sole assumption that no large-scale reliable quantum storage is available to the cheating party. We construct novel protocols for oblivious transfer and bit commitment, ... More

Alexandrov meets KirszbraunDec 27 2010Dec 18 2017We give a simplified proof of the generalized Kirszbraun theorem for Alexandrov spaces, which is due to Lang and Schroeder. We also discuss related questions, both solved and open.

On the classification of vertex-transitive structuresJul 08 2017Oct 30 2018We consider the classification problem for several classes of countable structures which are "vertex-transitive", meaning that the automorphism group acts transitively on the elements. (This is sometimes called homogeneous.) We show that the classification ... More

Resolving Stanley's e-positivity of claw-contractible-free graphsMar 16 2017In Stanley's seminal 1995 paper on the chromatic symmetric function, he stated that there was no known graph that was not contractible to the claw and whose chromatic symmetric function was not e-positive, namely, not a positive linear combination of ... More

Elements and Principles of Data AnalysisMar 18 2019The data revolution has led to an increased interest in the practice of data analysis. As a result, there has been a proliferation of "data science" training programs. Because data science has been previously defined as an intersection of already-established ... More

Clocks and Relationalism in the Thermal Time HypothesisAug 03 2011The Thermal Time Hypotheis (TTH) has been proposed as a general method for identifying a time variable from within background-free theories which do not come equipped with a pre-defined clock variable. Here, we explore some implications of the TTH in ... More

Generalised Cantor sets and the dimension of productsJul 02 2014Sep 16 2014In this paper we consider the relationship between the Assouad and box-counting dimension and how both behave under the operation of taking products. We introduce the notion of `equi-homogeneity' of a set, which requires a uniformity in the size of local ... More

Arginine-Phosphate Salt Bridges Between Histones and DNA: Intermolecular Actuators that Control Nucleosome ArchitectureApr 17 2014Oct 01 2014Structural bioinformatics and van der Waals density functional theory are combined to investigate the mechanochemical impact of a major class of histone-DNA interactions, namely the formation of salt bridges between arginine residues in histones and phosphate ... More

On the continuity of global attractorsJul 11 2014Let $\Lambda$ be a complete metric space, and let $\{S_\lambda(\cdot):\ \lambda\in\Lambda\}$ be a parametrised family of semigroups with global attractors ${\mathscr A}_\lambda$. We assume that there exists a fixed bounded set $D$ such that ${\mathscr ... More

Gas Stripping in Simulated Galaxies with a Multiphase ISMJan 14 2009Cluster galaxies moving through the intracluster medium (ICM) are expected to lose some of their interstellar medium (ISM) through ISM-ICM interactions. We perform high resolution (40 pc) three-dimensional hydrodynamical simulations of a galaxy undergoing ... More

Scaling properties of noise-induced switching in a bistable tunnel diode circuitFeb 23 2019Noise-induced switching between coexisting metastable states occurs in a wide range of far-from-equilibrium systems including micro-mechanical oscillators, epidemiological and climate change models, and nonlinear electronic transport in tunneling structures ... More

A Finite Element Based P3M Method for N-body ProblemsMar 30 2015We introduce a fast mesh-based method for computing N-body interactions that is both scalable and accurate. The method is founded on a particle-particle--particle-mesh P3M approach, which decomposes a potential into rapidly decaying short-range interactions ... More

Some results in support of the Kakeya ConjectureJul 24 2014May 04 2017A Besicovitch set is a subset of $\R^d$ that contains a unit line segment in every direction and the famous Kakeya conjecture states that Besicovitch sets should have full dimension. We provide a number of results in support of this conjecture in a variety ... More

Learning Unitary Operators with Help From u(n)Jul 17 2016Nov 14 2016A major challenge in the training of recurrent neural networks is the so-called vanishing or exploding gradient problem. The use of a norm-preserving transition operator can address this issue, but parametrization is challenging. In this work we focus ... More

Star Formation in Ram Pressure Stripped TailsMar 01 2012We investigate the impact of star formation and feedback on ram pressure stripping using high-resolution adaptive mesh simulations, building on a previous series of papers that systematically investigated stripping using a realistic model for the interstellar ... More

Learning Unitary Operators with Help From u(n)Jul 17 2016Jan 10 2017A major challenge in the training of recurrent neural networks is the so-called vanishing or exploding gradient problem. The use of a norm-preserving transition operator can address this issue, but parametrization is challenging. In this work we focus ... More

The Tail of the Stripped Gas that Cooled: HI, Halpha and X-ray Observational Signatures of Ram Pressure StrippingSep 17 2009Galaxies moving through the intracluster medium (ICM) of a cluster of galaxies can lose gas via ram pressure stripping. This stripped gas forms a tail behind the galaxy which is potentially observable. In this paper, we carry out hydrodynamical simulations ... More

The Impact of ICM Substructure on Ram Pressure StrippingJul 31 2008Cluster galaxies moving through the intracluster medium (ICM) are expected to lose some of their interstellar medium (ISM) through ram pressure stripping and related ISM-ICM interactions. Using high-resolution cosmological simulations of a large galaxy ... More