Searching Arxiv, refresh for possibly better results.

total 209288took 0.14s

Characterization and valuation of uncertainty of calibrated parameters in stochastic decision modelsJun 11 2019We evaluated the implications of different approaches to characterize uncertainty of calibrated parameters of stochastic decision models (DMs) in the quantified value of such uncertainty in decision making. We used a microsimulation DM of colorectal cancer ... More

The two-body potential of Vainshtein screened theoriesMay 17 2019Adding a light scalar degree of freedom to General Relativity often induces a fifth force whose magnitude is strongly constrained by laboratory experiments and solar system tests. The Vainshtein screening mechanism ensures that the effects of this supplementary ... More

Irrelevant Exceptional Divisors for Curves on a Smooth SurfaceNov 24 2006Aug 28 2007Given a singular curve on a smooth surface, we determine which exceptional divisors on the minimal resolution of that curve contribute toward its jumping numbers.

The measure of PBR's realityOct 25 2018We review the Pusey-Barret-Rudolph (PBR) theorem\cite{PBR} and their setup, and arrive to the conclusion that the reality of a quantum state $\psi$ is intrinsically attached to the measurement the system described by $\psi$ has undergone. We show that ... More

Quantum Locality, Rings a Bell?: Bell's inequality meets local reality and true determinismMay 27 2016Nov 30 2017By assuming a deterministic evolution of quantum systems and taking realism into account, we carefully build a hidden variable theory for Quantum Mechanics based on the notion of ontological states proposed by 't Hooft. We view these ontological states ... More

The Solar Wind Charge-Exchange Production Factor for HydrogenMar 16 2015The production factor, or broad band averaged cross-section, for solar wind charge-exchange with hydrogen producing emission in the ROSAT 1/4 keV (R12) band is $3.8\pm0.2\times10^{-20}$ count degree$^{-2}$ cm$^4$. This value is derived from a comparison ... More

Fundamental Solutions for Hyperbolic Operators with Variable CoefficientsJan 19 2010In this article we describe the novel method to construct fundamental solutions for operators with variable coefficients. That method was introduced in "A note on the fundamental solution for the Tricomi-type equation in the hyperbolic domain"(J. Differential ... More

A special case of completion invariance for the $c_2$ invariant of a graphJun 27 2017Jan 25 2018The $c_2$ invariant is an arithmetic graph invariant defined by Schnetz. It is useful for understanding Feynman periods. Brown and Schnetz conjectured that the $c_2$ invariant has a particular symmetry known as completion invariance. This paper will prove ... More

A bijection between certain quarter plane walks and Motzkin pathsDec 03 2014This short note gives a bijection between quarter plane walks using the steps $\{\rightarrow, \searrow, \downarrow, \leftarrow, \nwarrow, \uparrow\}$ and bicoloured Motzkin paths.

The Erdos-Ko-Rado theorem for perfect matchingsNov 18 2009Jun 07 2010A $2k$-matching is a perfect matching of the complete graph on $2k$ vertices. Two $2k$-matchings are defined to be $t$-intersecting if they have at least $t$ edges in common. The main result in this paper is that if $k \geq 3t/2+1$, then the largest system ... More

Semilinear Hyperbolic Equations in Curved SpacetimeMay 19 2013This is a survey of the author's recent work rather than a broad survey of the literature. The survey is concerned with the global in time solutions of the Cauchy problem for matter waves propagating in the curved spacetimes, which can be, in particular, ... More

Some combinatorial interpretations in perturbative quantum field theoryFeb 01 2013Aug 21 2013This paper will describe how combinatorial interpretations can help us understand the algebraic structure of two aspects of perturbative quantum field theory, namely analytic Dyson-Schwinger equations and periods of scalar Feynman graphs. The particular ... More

A study on prefixes of $c_2$ invariantsMay 29 2018Sep 04 2018This document begins by reviewing recent progress that has been made by taking a combinatorial perspective on the $c_2$ invariant, an arithmetic graph invariant with connections to Feynman integrals. Then it proceeds to report on some recent calculations ... More

Regularity Criterion for the Three-dimensional Boussinesq EquationsSep 24 2015Jun 27 2017We prove that a solution to the three-dimensional Boussinesq equations does not blow-up at time T if $\| u_{\le Q}\|_{B^1_{\infty, \infty}}$ is integrable on $(0, T)$, where $u_{\le Q }$ represents the low modes of Littlewood-Paley projection of the velocity ... More

Small-time fluctuations for the bridge in a model class of hypoelliptic diffusions of weak Hörmander typeAug 13 2018We study the small-time asymptotics for hypoelliptic diffusion processes conditioned by their initial and final positions, in a model class of diffusions satisfying a weak H\"ormander condition where the diffusivity is constant and the drift is linear. ... More

Erdos-Ko-Rado theorem for the group $\textrm{PSU}(3,q)$Aug 28 2017In this paper we consider the derangement graph for the group $\textrm{PSU}(3,q)$ where $q$ is a prime power. We calculate all eigenvalues for this derangement graph and use these eigenvalues to prove that $\textrm{PSU}(3,q)$ has the Erd\H{o}s-Ko-Rado ... More

The topology and geometry of automorphism groups of free groupsOct 26 2016In the 1970s Stallings showed that one could learn a great deal about free groups and their automorphisms by viewing the free groups as fundamental groups of graphs and modeling their automorphisms as homotopy equivalences of graphs. Further impetus for ... More

Huygens' Principle for the Klein-Gordon equation in the de Sitter spacetimeJun 01 2012Oct 09 2012In this article we prove that the Klein-Gordon equation in the de Sitter spacetime obeys the Huygens' principle only if the physical mass $m$ of the scalar field and the dimension $n\geq 2$ of the spatial variable are tied by the equation $m^2=(n^2-1)/4 ... More

A Hopf algebraic approach to Schur function identitiesNov 19 2015Jun 09 2017Using cocommutativity of the Hopf algebra of symmetric functions, certain skew Schur functions are proved to be equal. Some of these skew Schur function identities are new.

Global existence of the self-interacting scalar field in the de Sitter universeJun 22 2017Nov 26 2018We present some sufficient conditions for the global in time existence of solutions of the semilinear Klein-Gordon equation of the self-interacting scalar field with complex mass. The coefficients of the equation depend on spatial variables as well, that ... More

On overcoming the Curse of Dimensionality in Neural NetworksSep 02 2018Dec 10 2018Let $A$ be a set, $V$ a Hilbert space. Let $H$ be a Hilbert space of functions $f:A\to V$ such that we have $\sup_{x\in A}\Vert f(x)\Vert_{V}\leq M \Vert f\Vert_H$. For $i=1,\cdots,n$, let $(x_i,y_i)\in A\times V$ comprise our dataset. Let $f^*\in H$ ... More

Approximation schemes for countably-infinite linear programs with moment boundsOct 08 2018We introduce approximation schemes for a type of countably-infinite-dimensional linear programs (CILPs) whose feasible points are unsigned measures and whose optimal values are bounds on the averages of these measures. In particular, we explain how to ... More

Approximations of countably-infinite linear programs over bounded measure spacesOct 08 2018Jun 15 2019We study a class of countably-infinite-dimensional linear programs (CILPs) whose feasible sets are bounded subsets of appropriately defined weighted spaces of measures. We show how to approximate the optimal value, optimal points, and minimal points of ... More

Robust topology optimization of three-dimensional photonic-crystal band-gap structuresMay 17 2014May 20 2014We perform full 3D topology optimization (in which "every voxel" of the unit cell is a degree of freedom) of photonic-crystal structures in order to find optimal omnidirectional band gaps for various symmetry groups, including fcc (including diamond), ... More

The Intrinsically X-ray Weak Quasar PHL 1811. I. X-ray Observations and Spectral Energy DistributionNov 10 2006This is the first of two papers reporting observations and analysis of the unusually bright (m_b=14.4), luminous (M_B=-25.5), nearby (z=0.192) narrow-line quasar PHL 1811, focusing on the X-ray properties and the spectral energy distribution. Two Chandra ... More

QPot: An R Package for Stochastic Differential Equation Quasi-Potential AnalysisOct 27 2015QPot is an R package for analyzing two-dimensional systems of stochastic differential equations. It provides users with a wide range of tools to simulate, analyze, and visualize the dynamics of these systems. One of QPot's key features is the computation ... More

Limitations on the quantum non-Gaussian characteristic of Schrödinger kitten state generationApr 01 2013A quantitative analysis is conducted on the impacts of experimental imperfections in the input state, the detector properties, and their interactions on photon-subtracted squeezed vacuum states in terms of a quantum non-Gaussian character witness and ... More

Bounding stationary averages of polynomial diffusions via semidefinite programmingJun 03 2016We introduce an algorithm based on semidefinite programming that yields increasing (resp. decreasing) sequences of lower (resp. upper) bounds on polynomial stationary averages of diffusions with polynomial drift vector and diffusion coefficients. The ... More

The origin of the 'local' 1/4 keV X-ray flux in both charge exchange and a hot bubbleJul 28 2014The Solar neighborhood is the closest and most easily studied sample of the Galactic interstellar medium, an understanding of which is essential for models of star formation and galaxy evolution. Observations of an unexpectedly intense diffuse flux of ... More

Solar Wind Charge Exchange contribution to the ROSAT All Sky Survey MapsMar 10 2016Jul 12 2016DXL (Diffuse X-ray emission from the Local Galaxy) is a sounding rocket mission designed to estimate the contribution of Solar Wind Charge eXchange (SWCX) to the Diffuse X-ray Background (DXB) and to help determine the properties of the Local Hot Bubble ... More

The Structure of the Local Hot BubbleNov 16 2016DXL (Diffuse X-rays from the Local Galaxy) is a sounding rocket mission designed to quantify and characterize the contribution of Solar Wind Charge eXchange (SWCX) to the Diffuse X-ray Background and study the properties of the Local Hot Bubble (LHB). ... More

Non-stationary phase of the MALA algorithmAug 30 2016The Metropolis-Adjusted Langevin Algorithm (MALA) is a Markov Chain Monte Carlo method which creates a Markov chain reversible with respect to a given target distribution, ?N, with Lebesgue density on R^N; it can hence be used to approximately sample ... More

Generalized chord diagram expansions of Dyson-Schwinger equationsFeb 08 2016Series solutions for a large family of single equation Dyson-Schwinger equations are given as expansions over decorated rooted connected chord diagrams. The analytic input to the new expansions are the expansions of the regularized integrals for the primitive ... More

Fundamental Solutions for the Klein-Gordon Equation in de Sitter SpacetimeMar 20 2008In this article we construct the fundamental solutions for the Klein-Gordon equation in de Sitter spacetime. We use these fundamental solutions to represent solutions of the Cauchy problem and to prove $L^p-L^q$ estimates for the solutions of the equation ... More

Fundamental Solutions for Wave Equation in de Sitter Model of UniverseOct 20 2007In this article we construct the fundamental solutions for the wave equation arising in the de Sitter model of the universe. We use the fundamental solutions to represent solutions of the Cauchy problem and to prove the $L^p-L^q$-decay estimates for the ... More

Global in Time Existence of Self-Interacting Scalar Field in De Sitter SpacetimesFeb 11 2016Nov 23 2018We prove the existence of a global in time solution of the semilinear Klein-Gordon equation in the de Sitter space-time.

Lower bounds for bootstrap percolation on Galton-Watson treesFeb 18 2014Bootstrap percolation is a cellular automaton modelling the spread of an `infection' on a graph. In this note, we prove a family of lower bounds on the critical probability for $r$-neighbour bootstrap percolation on Galton--Watson trees in terms of moments ... More

A new proof for the Erdős-Ko-Rado Theorem for the alternating groupFeb 28 2013A subset $S$ of the alternating group on $n$ points is {\it intersecting} if for any pair of permutations $\pi,\sigma$ in $S$, there is an element $i\in \{1,\dots,n\}$ such that $\pi(i)=\sigma(i)$. We prove that if $S$ is intersecting, then $|S|\leq \frac{(n-1)!}{2}$. ... More

An Erdős-Ko-Rado theorem for the derangement graph of PGL(3,q) acting on the projective planeOct 09 2013In this paper we prove an Erd\H{o}s-Ko-Rado-type theorem for intersecting sets of permutations. We show that an intersecting set of maximal size in the projective general linear group PGL(3,q), in its natural action on the points of the projective line, ... More

The Erdős-Ko-Rado property for some 2-transitive groupsAug 02 2013A subset of a group G of Sym(n) is intersecting if for any pair of permutations $\pi,\sigma \in G$ there is an $i$ in {1,2,...,n} such that $\pi(i) = \sigma(i)$. It has been shown, using an algebraic approach, that the largest intersecting sets in each ... More

Diffusion Limit For The Random Walk Metropolis Algorithm Out Of stationarityMay 19 2014Aug 30 2016The Random Walk Metropolis (RWM) algorithm is a Metropolis- Hastings MCMC algorithm designed to sample from a given target distribution \pi with Lebesgue density on R^N. RWM constructs a Markov chain by randomly proposing a new position (the "proposal ... More

Morita classes in the homology of Aut(F_n) vanish after one stabilizationJun 20 2006Jun 01 2007There is a series of cycles in the rational homology of the groups Out(F_n), first discovered by S. Morita, which have an elementary description in terms of finite graphs. The first two of these give nontrivial homology classes, and it is conjectured ... More

Renormalizability, fundamentality and a final theory: The role of UV-completion in the search for quantum gravityMay 18 2017Jul 20 2017Principles are central to physical reasoning, particularly in the search for a theory of quantum gravity (QG), where novel empirical data is lacking. One principle widely adopted in the search for QG is UV completion: the idea that a theory should (formally) ... More

Diffeomorphisms of quantum fieldsOct 06 2016Mar 05 2017We study field diffeomorphisms $\Phi(x)= F(\rho(x))=a_0\rho(x)+a_1\rho^2(x)+\ldots=\sum_{j+0}^\infty a_j \rho^{j+1}$, for free and interacting quantum fields $\Phi$. We find that the theory is invariant under such diffeomorphisms if and only if kinematic ... More

Regularizing Effect of the Forward Energy Cascade in the Inviscid Dyadic ModelOct 28 2013Feb 28 2014We study the inviscid dyadic model of the Euler equations and prove some regularizing properties of the nonlinear term that occur due to forward energy cascade. We show every solution must have 3/5 L^2-based (or 1/10 L^3-based) regularity for all positive ... More

Cube complexes and abelian subgroups of automorphism groups of RAAGsFeb 03 2019Apr 02 2019We construct free abelian subgroups of the group $U(A_\Gamma)$ of untwisted outer automorphisms of a right-angled Artin group, thus giving lower bounds on the virtual cohomological dimension. The group $U(A_\Gamma)$ was previously studied by Charney, ... More

An algebraic proof of the Erdős-Ko-Rado theorem for intersecting families of perfect matchingsJun 29 2015In this paper we give a proof that the largest set of perfect matchings, in which any two contain a common edge, is the set of all perfect matchings that contain a fixed edge. This is a version of the famous Erd\H{o}s-Ko-Rado theorem for perfect matchings. ... More

Next-to$^k$ leading log expansions by chord diagramsJun 12 2019Green functions in a quantum field theory can be expanded as bivariate series in the coupling and a scale parameter. The leading logs are given by the main diagonal of this expansion, i.e. the subseries where the coupling and the scale parameter appear ... More

A new proof of the Erdős-Ko-Rado theorem for intersecting families of permutationsOct 10 2007Let S(n) be the symmetric group on n points. A subset S of S(n) is intersecting if for any pair of permutations \pi, \sigma in S there is a point i in {1,...,n} such that \pi(i)=\sigma(i). Deza and Frankl \cite{MR0439648} proved that if S a subset of ... More

Infinitesimal Operations on Complexes of GraphsNov 19 2001Aug 02 2003In two seminal papers Kontsevich used a construction called_graph homology_ as a bridge between certain infinite dimensional Lie algebras and various topological objects, including moduli spaces of curves, the group of outer automorphisms of a free group, ... More

Manickam-Miklós-Singhi Conjectures on Partial GeometriesJun 20 2016Aug 10 2017In this paper we give a proof of the Manickam-Mikl\'os-Singhi (MMS) conjecture for some partial geometries. Specifically, we give a condition on partial geometries which implies that the MMS conjecture holds. Further, several specific partial geometries ... More

Morita classes in the homology of automorphism groups of free groupsJun 19 2004Dec 11 2004Using Kontsevich's identification of the homology of the Lie algebra l_infty with the cohomology of Out(F_r), Morita defined a sequence of 4k-dimensional classes mu_k in the unstable rational homology of Out(F_{2k+2}). He showed by a computer calculation ... More

The Erdős-Ko-Rado property for some permutation groupsNov 27 2013A subset in a group $G \leq Sym(n)$ is intersecting if for any pair of permutations $\pi,\sigma$ in the subset there is an $i \in \{1,2,\dots,n\}$ such that $\pi(i) = \sigma(i)$. If the stabilizer of a point is the largest intersecting set in a group, ... More

c_2 Invariants of Recursive Families of GraphsJan 05 2017May 22 2017The c_2 invariant, defined by Schnetz in 2011, is an arithmetic graph invariant created towards a better understanding of Feynman integrals. This paper looks at some graph families of interest, with a focus on decompleted toroidal grids. Specifically, ... More

A sharp threshold for a modified bootstrap percolation with recoveryMay 29 2015Bootstrap percolation is a type of cellular automaton on graphs, introduced as a simple model of the dynamics of ferromagnetism. Vertices in a graph can be in one of two states: `healthy' or `infected' and from an initial configuration of states, healthy ... More

The geometric interpretation of Froberg-Iarrobino conjectures on infinitesimal neighbourhoods of points in projective spaceSep 19 2003The study of infinitesimal deformations of a variety embedded in projective space requires that of deformations of a collection of points, as specified by a zero-dimensional scheme. Further, basic problems in infinitesimal interpolation correspond directly ... More

Intersecting generalised permutationsMar 10 2014For any positive integers $k,r,n$ with $r \leq \min\{k,n\}$, let $\mathcal{P}_{k,r,n}$ be the family of all sets $\{(x_1,y_1), \dots, (x_r,y_r)\}$ such that $x_1, \dots, x_r$ are distinct elements of $[k] = \{1, \dots, k\}$ and $y_1, \dots, y_r$ are distinct ... More

The $k$-Dominating GraphSep 24 2012Mar 01 2013Given a graph $G$, the $k$-dominating graph of $G$, $D_k(G)$, is defined to be the graph whose vertices correspond to the dominating sets of $G$ that have cardinality at most $k$. Two vertices in $D_k(G)$ are adjacent if and only if the corresponding ... More

Tensor structure from scalar Feynman matroidsOct 27 2010Mar 06 2011We show how to interpret the scalar Feynman integrals which appear when reducing tensor integrals as scalar Feynman integrals coming from certain nice matroids.

An Erdos-Ko-Rado theorem for the derangement graph of PGL(2,q) acting on the projective lineOct 16 2009Oct 21 2010Let G=PGL(2,q) be the projective general linear group acting on the projective line P_q. A subset S of G is intersecting if for any pair of permutations \pi,\sigma in S, there is a projective point p in P_q such that p^\pi=p^\sigma. We prove that if S ... More

An Erdős-Ko-Rado theorem for subset partitionsNov 27 2013A $k\ell$-subset partition, or $(k,\ell)$-subpartition, is a $k\ell$-subset of an $n$-set that is partitioned into $\ell$ distinct classes, each of size $k$. Two $(k,\ell)$-subpartitions are said to $t$-intersect if they have at least $t$ classes in common. ... More

Many-body Green's function theory for thin ferromagnetic films: exact treatment of the single-ion anisotropyJan 08 2002A theory for the magnetization of ferromagnetic films is formulated within the framework of many-body Green's funtion theory which considers all components of the magnetization. The model Hamiltonian includes a Heisenberg term, an external field, a second- ... More

Modelling cross-reactivity and memory in the cellular adaptive immune response to influenza infection in the hostJun 01 2016Nov 22 2016The cellular adaptive immune response plays a key role in resolving influenza infection. Experiments where individuals are successively infected with different strains within a short timeframe provide insight into the underlying viral dynamics and the ... More

Using the XMM Optical Monitor to Study Cluster Galaxy EvolutionDec 12 2011We explore the application of XMM-Newton Optical Monitor (XMM-OM) ultraviolet (UV) data to study galaxy evolution. Our sample is constructed as the intersection of all Abell clusters with z < 0.05 and having archival XMM-OM data in either the UVM2 or ... More

Demonstration of a 6-4 State Reference Frame Independent channel for Quantum Key DistributionMay 22 2019We propose and demonstrate a novel protocol for reference frame independent quantum key distribution using six states for Alice and four states for Bob. We show that this protocol can generate a secure key for any possible phase of the entangled state, ... More

Unification of Luminous Type 1 Quasars through CIV EmissionNov 10 2010Feb 21 2011Using a sample of 30,000 quasars from SDSS-DR7, we explore the range of properties exhibited by high-ionization, broad emission lines, such as CIV 1549. Specifically we investigate the anti-correlation between L_UV and emission line EQW (the Baldwin Effect) ... More

2MTF IV. A bulk flow measurement of the local UniverseSep 01 2014Using the 2MASS near-infrared photometry and high signal-to-noise HI 21-cm data from the Arecibo, Green Bank, Nancay, and Parkes telescopes, we calculate the redshift-independent distances and peculiar velocities of 2,018 bright inclined spiral galaxies ... More

2MTF II. New Parkes 21-cm observations of 303 southern galaxiesApr 03 2013We present new 21-cm neutral hydrogen (HI) observations of spiral galaxies for the 2MASS Tully Fisher (2MTF) survey. Using the 64-m Parkes radio telescope multibeam system we obtain 152 high signal-to-noise HI spectra from which we extract 148 high-accuracy ... More

2MTF V. Cosmography, Beta, and the residual bulk flowNov 16 2015Using the Tully-Fisher relation, we derive peculiar velocities for the 2MASS Tully-Fisher Survey and describe the velocity field of the nearby Universe. We use adaptive kernel smoothing to map the velocity field, and compare it to reconstructions based ... More

2MTF VI. Measuring the velocity power spectrumJun 16 2017We present measurements of the velocity power spectrum and constraints on the growth rate of structure $f\sigma_{8}$, at redshift zero, using the peculiar motions of 2,062 galaxies in the completed 2MASS Tully-Fisher survey (2MTF). To accomplish this ... More

Model distinguishability and inference robustness in mechanisms of cholera transmission and loss of immunityMay 22 2016Mathematical models of cholera and waterborne disease vary widely in their structures, in terms of transmission pathways, loss of immunity, and other features. These differences may yield different predictions and parameter estimates from the same data. ... More

Valuations and FrobeniusJul 21 2015Dec 29 2016The behavior of the Frobenius map is investigated for valuation rings of prime characteristic. We show that valuation rings are always F-pure. We introduce a generalization of the notion of strong F-regularity, which we call F-pure regularity, and show ... More

Tree hook length formulae, Feynman rules and B-seriesDec 18 2014We consider weighted generating functions of trees where the weights are products of functions of the sizes of the subtrees. This work begins with the observation that three different communities, largely independently, found substantially the same result ... More

Flow rate of transport network controls uniform metabolite supply to tissueJul 18 2017Jul 05 2018Life and functioning of higher organisms depends on the continuous supply of metabolites to tissues and organs. What are the requirements on the transport network pervading a tissue to provide a uniform supply of nutrients, minerals, or hormones? To theoretically ... More

Many-body Green's function theory of ferromagnetic Heisenberg systems with single-ion anisotropies in more than one directionJul 07 2004Jul 08 2004The behaviour of ferromagnetic systems with single-ion anisotropies in more than one direction is investigated with many-body Green's function theory generalizing earlier work with uniaxial anisotropies only. It turns out to be of advantage to construct ... More

Excellence in prime characteristicApr 12 2017Jan 18 2018Fix any field $K$ of characteristic $p$ such that $[K:K^p]$ is finite. We discuss excellence for Noetherian domains whose fraction field is $K$, showing for example, that $R$ is excellent if and only if the Frobenius map is finite on $R$. Furthermore, ... More

Data-Driven Approach to Simulating Realistic Human Joint ConstraintsSep 25 2017Apr 08 2018Modeling realistic human joint limits is important for applications involving physical human-robot interaction. However, setting appropriate human joint limits is challenging because it is pose-dependent: the range of joint motion varies depending on ... More

MC^2: Galaxy Imaging and Redshift Analysis of the Merging Cluster CIZA J2242.8+5301Oct 10 2014X-ray and radio observations of CIZA J2242.8+5301 suggest that it is a major cluster merger. Despite being well studied in the X-ray, and radio, little has been presented on the cluster structure and dynamics inferred from its galaxy population. We carried ... More

X-ray, UV, and Radio Timing Observations of the Radio Galaxy 3C 120Sep 25 2018We report the results of monitoring of the radio galaxy 3C 120 with the Neil Gehrels Swift Observatory, Very Long Baseline Array, and Mets\"ahovi Radio Observatory. The UV-optical continuum spectrum and R-band polarization can be explained by a superposition ... More

WISE TF: A Mid-infrared, 3.4-micron Extension of the Tully-Fisher Relation Using WISE PhotometryMay 20 2013We present a mid-infrared Tully-Fisher (TF) relation using photometry from the 3.4-micron W1 band of the Wide-field Infrared Survey Explorer (WISE) satellite. The WISE TF relation is formed from 568 galaxies taken from the all-sky 2MASS Tully-Fisher (2MTF) ... More

Significant Phonon Drag Enables High Power Factor in the AlGaN/GaN Two-Dimensional Electron GasSep 21 2018May 15 2019In typical thermoelectric energy harvesters and sensors, the Seebeck effect is caused by diffusion of electrons or holes in a temperature gradient. However, the Seebeck effect can also have a phonon drag component, due to momentum exchange between charge ... More

The Dehn functions of Out(F_n) and Aut(F_n)Nov 05 2010Nov 26 2011For n > 2, the Dehn functions of Aut(F_n) and Out(F_n) are exponential. Hatcher and Vogtmann proved that they are at most exponential, and the complementary lower bound in the case n=3 was established by Bridson and Vogtmann. Handel and Mosher completed ... More

Abelian covers of graphs and maps between outer automorphism groups of free groupsJul 15 2010Jul 28 2011We explore the existence of homomorphisms between outer automorphism groups of free groups Out(F_n) \to Out(F_m). We prove that if n > 8 is even and n \neq m \leq 2n, or n is odd and n \neq m \leq 2n - 2, then all such homomorphisms have finite image; ... More

1+1 wave maps into symmetric spacesNov 06 2003We explain how to apply techniques from integrable systems to construct $2k$-soliton homoclinic wave maps from the periodic Minkowski space $S^1\times R^1$ to a compact Lie group, and more generally to a compact symmetric space. We give a correspondence ... More

Friction and Pressure-Dependence of Force Chain Communities in Granular MaterialsAug 23 2015Granular materials transmit stress via a network of force chains. Despite the importance of these chains to characterizing the stress state and dynamics of the system, there is no common framework for quantifying their their properties. Recently, attention ... More

2MTF III. HI 21cm observations of 1194 spiral galaxies with the Green Bank TelescopeJun 23 2014We present HI 21cm observations of 1194 galaxies out to a redshift of 10,000 km/s selected as inclined spirals (i>60deg) from the 2MASS Redshift Survey. These observations were carried out at the National Radio Astronomy Observatory Robert C. Byrd Green ... More

Assessing molecular simulation for the analysis of lipid monolayer reflectometryJan 16 2019Mar 21 2019Using molecular simulation to aid in the analysis of neutron reflectometry measurements is commonplace. However, reflectometry is a tool to probe large-scale structures, and therefore the use of all-atom simulation may be irrelevant. This work presents ... More

XMM-Newton Observation of Solar Wind Charge Exchange EmissionApr 19 2004We present an XMM-Newton spectrum of diffuse X-ray emission from within the solar system. The spectrum is dominated by probable C VI lines at 0.37 keV and 0.46 keV, an O VII line at 0.56 keV, O VIII lines at 0.65 keV and ~0.8 keV, Ne IX lines at ~0.92 ... More

HST STIS Ultraviolet Spectral Evidence of Outflow in Extreme Narrow-line Seyfert 1 Galaxies: II. Modeling and InterpretationFeb 19 2004Apr 11 2004We present modeling to explore the conditions of the broad-line emitting gas in two extreme Narrow-line Seyfert 1 galaxies, using the observational results described in the first paper of this series. Photoionization modeling using Cloudy was conducted ... More

A Comprehensive Spectral and Variability Study of Narrow-Line Seyfert 1 Galaxies Observed by ASCA: II. Spectral Analysis and CorrelationsJul 21 1999(Abridged) I present a comprehensive and uniform analysis of 25 {\it ASCA} observations from 23 Narrow-line Seyfert 1 galaxies. The spectral analysis and correlations are presented in this paper, Part 2; the reduction and time series analysis is presented ... More

Estimate of a Trigonometrical Sum Involving Naturals with Binary Decompositions of a Special KindMay 26 2008Let $\mathbb{N}_0$ be a class of natural numbers whose binary decompositions has even number of 1. We estimate of the sum $\sum\limits_{n\in \mathbf{N}_0,n\le X}\exp(2\pi i \alpha n^2)$.

The Spectral Energy Distributions of Narrow-line Seyfert 1 GalaxiesFeb 27 2004Narrow-line Seyfert 1 galaxies are identified by their uniform optical spectral properties. Studies of samples of NLS1s reveal, however, a range of X-ray spectral and variability behavior, and UV spectral behavior. We describe the range of behavior observed, ... More

STIS Ultraviolet Spectral Evidence for Outflows in Extreme Narrow-Line Seyfert 1 GalaxiesDec 08 2000(abridged) I present and discuss the results of HST STIS observations of IRAS 13224-3809 and 1H 0707-495, two narrow-line Seyfert 1 (NLS1) galaxies. We discovered that high-ionization UV emission lines are much broader and strongly blueshifted compared ... More

Selection and Coalescence in a Finite State ModelJan 04 2017To introduce selection into a model of coalescence, I explore the use of modified integer partitions that allow the identification of a preferred lineage. I show that a partition-partition transition matrix, along with Monte Carlo discrete time kinetics, ... More

Momentum partition between constituents of exotic atoms during laser induced tunneling ionizationMay 18 2015The tunneling ionization of exotic atoms such as muonic hydrogen, muonium and positronium in a strong laser field of circular polarization is investigated taking into account the impact of the motion of the center of mass on the the tunneling ionization ... More

Predicting Recall Probability to Adaptively Prioritize StudyFeb 28 2018Students have a limited time to study and are typically ineffective at allocating study time. Machine-directed study strategies that identify which items need reinforcement and dictate the spacing of repetition have been shown to help students optimize ... More

On the space-time Monopole equationFeb 27 2006The space-time monopole equation is obtained from a dimension reduction of the anti-self dual Yang-Mills equation on $\R^{2,2}$. A family of Ward equations is obtained by gauge fixing from the monopole equation. In this paper, we give an introduction ... More

Probing the temperature of cold many-body quantum systemsDec 08 2017Jun 14 2018It is "conventional wisdom" that the uncertainty of local temperature measurements on equilibrium systems diverges exponentially fast as their temperature $T$ drops to zero. In contrast, some exactly solvable models showcase a more benign power-law-like ... More

A Note on Wave Equation in Einstein & de Sitter SpacetimeAug 08 2009Feb 27 2010We consider the wave propagating in the Einstein & de Sitter spacetime. The covariant d'Alembert's operator in the Einstein & de Sitter spacetime belongs to the family of the non-Fuchsian partial differential operators. We introduce the initial value ... More

On the bordification of outer spaceSep 05 2017Feb 16 2018We give a simple construction of an equivariant deformation retract of Outer space which is homeomorphic to the Bestvina-Feighn bordification. This results in a much easier proof that the bordification is (2n-5)-connected at infinity, and hence that $Out(F_n)$ ... More