Results for "Patrick Drew"

total 7971took 0.13s
Delayed Blockchain ProtocolsApr 18 2018Given the parallels between game theory and consensus, it makes sense to intelligently design blockchain or DAG protocols with an incentive-compatible-first mentality. To that end, we propose a new blockchain or DAG protocol enhancement based on delayed ... More
The sorting order on a Coxeter groupDec 07 2007Mar 30 2009Let $(W,S)$ be an arbitrary Coxeter system. For each word $\omega$ in the generators we define a partial order--called the {\sf $\omega$-sorting order}--on the set of group elements $W_\omega\subseteq W$ that occur as subwords of $\omega$. We show that ... More
Motivic Hodge modulesJan 30 2018We construct a quasi-categorically enhanced Grothendieck six-functor formalism on schemes of finite type over the complex numbers. In addition to satisfying many of the same properties as M. Saito's derived categories of mixed Hodge modules, this new ... More
Electron intensity measurements by the Cluster/RAPID/IES instrument in Earths radiation belts and ring currentSep 04 2018The Cluster mission, launched in 2000, has produced a large database of electron flux intensity measurements in the Earths magnetosphere by the Research with Adaptive Particle Imaging Detector (RAPID)/ Imaging Electron Spectrometer (IES) instrument. However, ... More
Do Price Ranges Increase Click-throughs?May 15 2016An important goal of online comparison shopping services is to "convert" a viewer from general product category pages (for example product groups such as "smartphones" or "air-conditioners") to detailed product pages and ultimately to order pages. Comparison ... More
Observation of the Dyakonov-Tamm WaveNov 18 2013A surface electromagnetic wave called the Dyakonov-Tamm wave has been theoretically predicted to exist at the interface of two dielectric materials at least one of which is both anisotropic and periodically nonhomogeneous. For experimental confirmation, ... More
Vanishing lines for modules over the motivic Steenrod algebraFeb 13 2017Jan 24 2018We study criteria for freeness and for the existence of a vanishing line for modules over certain Hopf subalgebras of the motivic Steenrod algebra over $\mathrm{Spec}(\mathbb{C})$ at the prime 2. These turn out to be determined by the vanishing of certain ... More
Euler characteristic of the truncated order complex of generalized noncrossing partitionsMay 02 2009The purpose of this note is to complete the study, begun in the first author's PhD thesis, of the topology of the poset of generalized noncrossing partitions associated to real reflection groups. In particular, we calculate the Euler characteristic of ... More
Permutation WeightingJan 04 2019Feb 07 2019This work introduces permutation weighting: a weighting estimator for observational causal inference under general treatment regimes which preserves arbitrary measures of covariate balance. We show that estimating weights which obey balance constraints ... More
Topological SpeedupsMay 26 2016Given a dynamical system $(X,T)$ one can define a speedup of $(X,T)$ as another dynamical system conjugate to $S:X\rightarrow X$ where $S(x)=T^{p(x)}(x)$ for some function $p:X\rightarrow\mathbb{Z}^{+}$. In $1985$ Arnoux, Ornstein, and Weiss showed that ... More
Functional renormalization group approach to neutron matterApr 03 2014Sep 30 2014The chiral nucleon-meson model, previously applied to systems with equal number of neutrons and protons, is extended to asymmetric nuclear matter. Fluctuations are included in the framework of the functional renormalization group. The equation of state ... More
The magneto-optical Faraday effect in spin liquid candidatesJul 23 2014We propose an experiment to use the magneto-optical Faraday effect to probe the dynamic Hall conductivity of spin liquid candidates. Theory predicts that an external magnetic field will generate an internal gauge field. If the source of conductivity is ... More
Penumbral micro-jets at high spatial and temporal resolutionMay 08 2019May 20 2019Sunspot observations in chromospheric spectral lines have revealed the existence of short-lived linear bright transients, commonly referred to as penumbral micro-jets (PMJs). Details on the origin and physical nature of PMJs are to large extend still ... More
A decomposition of the group algebra of a hyperoctahedral groupNov 11 2016The descent algebra of a finite Coxeter group W is a subalgebra of the group algebra defined by Solomon. Descent algebras of symmetric groups have properties that are not shared by other Coxeter groups. For instance, the natural map from the descent algebra ... More
Taking Census of Massive, Star-Forming Galaxies formed <1 Gyr After the Big BangMar 13 2019Two decades of effort have been poured into both single-dish and interferometric millimeter-wave surveys of the sky to infer the volume density of dusty star-forming galaxies (DSFGs, with SFR>100M$_\odot$ yr$^{-1}$) over cosmic time. Though obscured galaxies ... More
GQA: a new dataset for compositional question answering over real-world imagesFeb 25 2019We introduce GQA, a new dataset for real-world visual reasoning and compositional question answering, seeking to address key shortcomings of previous VQA datasets. We have developed a strong and robust question engine that leverages scene graph structures ... More
Hierarchical Approaches for Reinforcement Learning in Parameterized Action SpaceOct 23 2018We explore Deep Reinforcement Learning in a parameterized action space. Specifically, we investigate how to achieve sample-efficient end-to-end training in these tasks. We propose a new compact architecture for the tasks where the parameter policy is ... More
Towards Least Privilege Containers with CimplifierFeb 26 2016Application containers, such as Docker containers, have recently gained popularity as a solution for agile and seamless deployment of applications. These light-weight virtualization environments run applications that are packed together with their resources ... More
Transforming how water is managed in the WestSep 28 2016California is challenged by its worst drought in 600 years and faces future water uncertainty. Pioneering new data infrastructure to integrate water use data across California's more than a thousand water providers will support water managers in ensuring ... More
An Analysis of ALMA Deep Fields and the Perceived Dearth of High-z GalaxiesJun 14 2018Deep, pencil-beam surveys from ALMA at 1.1-1.3mm have uncovered an apparent absence of high-redshift dusty galaxies, with existing redshift distributions peaking around $z\sim1.5-2.5$. This has led to a perceived dearth of dusty systems at $z>4$, and ... More
Strongly residual coordinates over A[x]Apr 05 2013May 14 2013For a domain A of characteristic zero, a polynomial f over A[x] is called a strongly residual coordinate if f becomes a coordinate (over A) upon going modulo x, and f becomes a coordinate upon inverting x. We study the question of when a strongly residual ... More
Venereau-type polynomials as potential counterexamplesJul 14 2010Sep 25 2012We study some properties of the Venereau polynomials b_m=y+x^m(xz+y(yu+z^2)), a sequence of proposed counterexamples to the Abhyankar-Sathaye embedding conjecture and the Dolgachev-Weisfeiler conjecture. It is well known that these are hyperplanes and ... More
Stratification and duality for homotopical groupsNov 09 2017In this paper, we show that the category of module spectra over $C^*(B\mathcal{G},\mathbb{F}_p)$ is stratified for any $p$-local compact group $\mathcal{G}$, thereby giving a support-theoretic classification of all localizing subcategories of this category. ... More
Near-infrared line spectropolarimetry of hot massive starsSep 22 2005In order to study the inner parts of the circumstellar material around optically faint, infrared bright objects, we present the first medium-resolution spectropolarimetric data taken in the near-infrared. In this paper we discuss Pa beta line data of ... More
The multi-detector F-statistic metric for short-duration non-precessing inspiral gravitational-wave signalsAug 11 2012We derive explicit expressions for the multi-detector F-statistic metric applied to short-duration non-precessing inspiral signals. This is required for template bank production associated with coherent searches for short-duration non-precessing inspiral ... More
Parameter space metric for 3.5 post-Newtonian gravitational-waves from compact binary inspiralsMay 23 2013We derive the metric on the parameter space of 3.5 post-Newtonian (3.5PN) stationary phase compact binary inspiral waveforms for a single detector, neglecting spin, eccentricity, and finite-body effects. We demonstrate that this leads to better template ... More
On stratification for spaces with Noetherian mod $p$ cohomologyApr 29 2019Let $X$ be a topological space with Noetherian mod $p$ cohomology and let $C^*(X;\mathbb{F}_p)$ be the commutative ring spectrum of $\mathbb{F}_p$-valued cochains on $X$. The goal of this paper is to exhibit conditions under which the category of module ... More
Verdier quotients of stable quasi-categories are localizationsNov 26 2015The Verdier quotient $\mathcal{T}/\mathcal{S}$ of a triangulated category $\mathcal{T}$ by a triangulated subcategory $\mathcal{S}$ is defined by a universal property with respect to triangulated functors out of $\mathcal{T}$. However, $\mathcal{T}/\mathcal{S}$ ... More
Hyperplane Arrangements and Diagonal HarmonicsMay 11 2010In 2003, Haglund's {\sf bounce} statistic gave the first combinatorial interpretation of the $q,t$-Catalan numbers and the Hilbert series of diagonal harmonics. In this paper we propose a new combinatorial interpretation in terms of the affine Weyl group ... More
Metrics for multi-detector template placement in searches for short-duration nonprecessing inspiral gravitational-wave signalsJul 16 2013Using the family of multi-detector F-statistic metrics for short duration, nonprecessing inspiral signals, we derive a marginalized metric that is directly applicable to the problem of generating template banks for coincident and coherent multi-detector ... More
The balancing act of template bank construction: inspiral waveform template banks for gravitational-wave detectors and optimizations at fixed computational costMar 08 2013Gravitational-wave searches for signals from inspiralling compact binaries have relied on matched filtering banks of waveforms (called template banks) to try to extract the signal waveforms from the detector data. These template banks have been constructed ... More
Factors influencing the decision of Saudi consumers to purchase form online retailers: Quantitative AnalysisNov 11 2012This paper presents the preliminary findings of a study researching the diffusion and the adoption of online retailing in Saudi Arabia. It reports new research that identifies and explores the key issues that positively and negatively influence the decision ... More
Multiagent Soft Q-LearningApr 25 2018Policy gradient methods are often applied to reinforcement learning in continuous multiagent games. These methods perform local search in the joint-action space, and as we show, they are susceptable to a game-theoretic pathology known as relative overgeneralization. ... More
Optimal $(t,r)$ Broadcasts On the Infinite GridNov 29 2017Let $G=(V,E)$ be a graph and $t,r$ be positive integers. The signal that a vertex $v$ receives from a tower of signal strength $t$ located at vertex $T$ is defined as $sig(v,T)=max(t-dist(v,T),0)$, where $dist(v,T)$ denotes the distance between the vertices ... More
Determining Tropical HypersurfacesSep 18 2015Sep 23 2016We consider the question of when points in tropical affine space uniquely determine a tropical hypersurface. We introduce a notion of multiplicity of points so that this question may be meaningful even if some of the points coincide. We give a geometric/combinatorial ... More
Use of Singular-Value Decomposition in Gravitational-Wave Data AnalysisJan 09 2012Singular-value decomposition is a powerful technique that has been used in the analysis of matrices in many fields. In this paper, we summarize how it has been applied to the analysis of gravitational-wave data. These include producing basis waveforms ... More
Normal subgroups generated by a single polynomial automorphismSep 13 2017Jan 24 2018We study criteria for deciding when the normal subgroup generated by a single polynomial automorphism of $\mathbb{A}^n$ is as large as possible, namely equal to the normal closure of the special linear group in the special automorphism group. In particular, ... More
Generalized Noncrossing Partitions and Combinatorics of Coxeter GroupsNov 04 2006Oct 18 2007This memoir constitutes the author's PhD thesis at Cornell University. It serves both as an expository work and as a description of new research. At the heart of the memoir, we introduce and study a poset $NC^{(k)}(W)$ for each finite Coxeter group $W$ ... More
2-D Monte Carlo simulations of H I line formation in massive YSO disk windsAug 03 2005Massive young stellar objects (YSOs) are powerful infrared H I line emitters. It has been suggested that these lines form in a outflow from a disk surrounding the YSO. Here, new two-dimensional Monte Carlo radiative transfer calculations are described ... More
Time-resolved ultraviolet spectroscopy of the compact interacting binary QU CarJul 01 2002We present HST/STIS (1160--1700A) echelle spectra of the cataclysmic variable (CV) star, QU Car, observed in time-tag mode at three epochs. In catalogues this binary is classified as a nova-like variable. We find evidence of a high-state non-magnetic ... More
Results and conjectures on simultaneous core partitionsAug 02 2013Apr 22 2014An n-core partition is an integer partition whose Young diagram contains no hook lengths equal to n. We consider partitions that are simultaneously a-core and b-core for two relatively prime integers a and b. These are related to abacus diagrams and the ... More
Rectification of Deligne's mixed Hodge structuresNov 26 2015We promote Beilinson's triangulated equivalence between the bounded derived category of rational polarizable mixed Hodge structures and the derived category of rational polarizable mixed Hodge complexes to an equivalence of symmetric monoidal quasi-categories. ... More
Self-Organizing Machine Translation: Example-Driven Induction of Transfer FunctionsJun 03 1994With the advent of faster computers, the notion of doing machine translation from a huge stored database of translation examples is no longer unreasonable. This paper describes an attempt to merge the Example-Based Machine Translation (EBMT) approach ... More
Dynamics of Irreducible Endomorphisms of $F_n$Aug 21 2010Mar 06 2011We consider the class non-surjective irreducible endomorphisms of the free group $F_n$. We show that such an endomorphism $\phi$ is topologically represented by a simplicial immersion $f:G \rightarrow G$ of a marked graph $G$; along the way we classify ... More
Observation of scattering and absorption centers in lead fluoride crystalsJun 22 2006For the first time, lead fluoride is used as a fast and compact material in electromagnetic calorimetry. Excellent optical and mechanical properties of the pure Cherenkov crystals are necessary for the A4 collaboration to perform a measurement of the ... More
Duality for toric Landau-Ginzburg modelsMar 04 2008We introduce a duality construction for toric Landau-Ginzburg models, applicable to complete intersections in toric varieties via the sigma model / Landau-Ginzburg model correspondence. This construction is shown to reconstruct those of Batyrev-Borisov, ... More
Large-scale bias of dark matter halosSep 06 2010Feb 09 2011We build a simple analytical model for the bias of dark matter halos that applies to objects defined by an arbitrary density threshold, $200\leq\deltas\leq 1600$, and that provides accurate predictions from low-mass to high-mass halos. We point out that ... More
Improving three-dimensional mass mapping with weak gravitational lensing using galaxy clusteringMar 28 2012Nov 01 2013The weak gravitational lensing distortion of distant galaxy images (defined as sources) probes the projected large-scale matter distribution in the Universe. To improve quality in the 3D mass mapping using 3D-lensing, we combine the lensing information ... More
Convergence in Infinitary Term Graph Rewriting Systems is Simple (Extended Abstract)Feb 26 2013In this extended abstract, we present a simple approach to convergence on term graphs that allows us to unify term graph rewriting and infinitary term rewriting. This approach is based on a partial order and a metric on term graphs. These structures arise ... More
Partial Order Infinitary Term RewritingMar 22 2014Jun 02 2014We study an alternative model of infinitary term rewriting. Instead of a metric on terms, a partial order on partial terms is employed to formalise convergence of reductions. We consider both a weak and a strong notion of convergence and show that the ... More
Braids in trivial braid diagramsNov 19 2003We show that every trivial 3-strand braid diagram contains a disk, defined as a ribbon ending in opposed crossings. Under a convenient algebraic form, the result extends to every Artin--Tits group of dihedral type, but it fails to extend to braids with ... More
Límites directos de prolongaciones de algebroides de LieOct 29 2013Jun 02 2016We prove that direct limits of finite dimensional Lie algebroids and their prolongations can be endowed with structures of convenient spaces.
A note on Flenner's extension theoremMay 06 2019We show that any $p$-form on the smooth locus of a normal complex space extends to a resolution of singularities, possibly with logarithmic poles, as long as $p \le \mathrm{codim}_X (X_{\mathrm{sg}}) - 2$, where $c$ is the codimension of the singular ... More
Differential forms on log canonical spaces in positive characteristicMay 06 2019Given a logarithmic $1$-form on the snc locus of a log canonical surface pair $(X, D)$ over a perfect field of characteristic $p \ge 7$, we show that it extends with at worst logarithmic poles to any resolution of singularities. We also prove the analogous ... More
Quasianalytic Ilyashenko algebrasJun 07 2016May 04 2017I construct a quasianalytic field $\mathcal F$ of germs at $+\infty$ of real functions with logarithmic generalized power series as asymp\-totic expansions, such that $\mathcal F$ is closed under differentiation and $\log$-composition; in particular, ... More
Thin groups of fractionsNov 27 2001A number of properties of spherical Artin groups extend to Garside groups, defined as the groups of fractions of monoids where least common multiples exist, there is no nontrivial unit, and some additional finiteness conditions are satisfied \cite{Dgk}. ... More
Molecules in QSOs and QSO Absorption Line Systems at High RedshiftApr 24 1998Molecules dominate the cooling function of neutral metal-poor gas at high density. Observation of molecules at high redshift is thus an important tool toward understanding the physical conditions prevailing in collapsing gas. Up to now, detections are ... More
High Energy Studies of Pulsar Wind NebulaeNov 12 2008The extended nebulae formed as pulsar winds expand into their surroundings provide information about the composition of the winds, the injection history from the host pulsar, and the material into which the nebulae are expanding. Observations from across ... More
Thermal X-ray Spectra of Supernova RemnantsSep 23 2013The fast shocks that characterize supernova remnants heat circumstellar and ejecta material to extremely high temperatures, resulting in significant X-ray emission. The X-ray spectrum from an SNR carries a wealth of information about the temperature and ... More
Chandra Studies of Nonthermal Emission from Supernova Remnants and Pulsar Wind NebulaeDec 16 2002While supernova remnants (SNRs) have long been considered prime candidates as sources of cosmic rays, it is only recently that X-ray observations have identified several shell-type SNRs dominated by nonthermal emission, thus revealing shock-accelerated ... More
Isolated-Word Confusion Metrics and the PGPfone AlphabetAug 29 1996Although the confusion of individual phonemes and features have been studied and analyzed since (Miller and Nicely, 1955), there has been little work done on extending this to a predictive theory of word-level confusions. The PGPfone alphabet is a good ... More
Incorporating "Unconscious Reanalysis" into an Incremental, Monotonic ParserFeb 24 1995This paper describes an implementation based on a recent model in the psycholinguistic literature. We define a parsing operation which allows the reanalysis of dependencies within an incremental and monotonic processing architecture, and discuss search ... More
Effective field theories for QED bound states: extending Nonrelativistic QED to study retardation effectsAug 29 1996Nonrelativistic QED bound states are difficult to study because of the presence of at least three widely different scales: the masses, three-momenta ($p_i$) and kinetic energies ($K_i$) of the constituents. Nonrelativistic QED (NRQED), an effective field ... More
Using groups for investigating rewrite systemsSep 18 2006We describe several technical tools that prove to be efficient for investigating the rewrite systems associated with a family of algebraic laws, and might be useful for more general rewrite systems. These tools consist in introducing a monoid of partial ... More
The critical height is a moduli heightOct 25 2016The critical height of a rational function (with algebraic coefficients) is a natural measure of dynamical complexity, essentially an adelic analogue of the Lyapunov exponent. Coordinate-free, it is well-defined on moduli space, but bears no obvious relation ... More
New Double-Mode and Other RR Lyrae Stars from WASP DataNov 05 201042 RRab, 46 RRc and 7 previously unidentified double-mode RR Lyrae stars were found in the publicly available data of the WASP archive. The Galactic double-mode RR Lyrae stars appear to show a bimodal period distribution.
CP, T and CPT violation in future long baseline experimentsOct 09 2002I give a short overview about the possibilities and problems related to the measurement of CP violation in long baseline experiments. Special attention is paid to the issue of degeneracies and a method for their resolution is quantitatively discussed. ... More
WIMPy LeptogenesisFeb 05 2014We consider a class of leptogenesis models in which the lepton asymmetry arises from dark matter annihilation processes which violate CP and lepton number. Importantly, a necessary one-loop contribution to the annihilation matrix element arises from absorptive ... More
Exact Algorithms for Maximum Clique: a computational studyJul 19 2012We investigate a number of recently reported exact algorithms for the maximum clique problem (MCQ, MCR, MCS, BBMC). The program code used is presented and critiqued showing how small changes in implementation can have a drastic effect on performance. ... More
Subdividing the cd-index of Eulerian PosetsApr 25 2016This thesis aims to give the reader an introduction and overview of the cd-index of a poset, as well as establish some new results. We give a combinatorial proof of Ehrenborg and Karu's cd-index subdivision decomposition for Gorenstein* complexes and ... More
Bogomolov-Sommese vanishing on log canonical pairsOct 01 2012May 06 2013Let (X, D) be a projective log canonical pair. We show that for any natural number p, the sheaf (Omega_X^p(log D))^** of reflexive logarithmic p-forms does not contain a Weil divisorial subsheaf whose Kodaira-Iitaka dimension exceeds p. This generalizes ... More
On consecutive quadratic non-residues: a conjecture of Issai SchurMay 21 2003Issai Schur once asked if it was possible to determine a bound, preferably using elementary methods, such that for all prime numbers p greater than the bound, the greatest number of consecutive quadratic non-residues modulo p is always less than the square ... More
Periodic points of algebraic functions and Deuring's class number formulaDec 11 2017Jan 01 2018The exact set of periodic points in $\overline{\mathbb{Q}}$ of the algebraic function $\widehat{F}(z)=(-1\pm \sqrt{1-z^4})/z^2$ is shown to consist of the coordinates of certain solutions $(x,y)=(\pi, \xi)$ of the Fermat equation $x^4+y^4=1$ in ring class ... More
Product formulas for the $5$-division points on the Tate normal form and the Rogers-Ramanujan continued fractionDec 19 2016Jun 11 2018Explicit formulas are proved for the $5$-torsion points on the Tate normal form $E_5$ of an elliptic curve having $(X,Y)=(0,0)$ as a point of order $5$. These formulas express the coordinates of points in $E_5[5] - \langle(0,0)\rangle$ as products of ... More
The converse to Curtiss' theorem for one-sided moment generating functionsJul 22 2008A set of necessary and sufficient conditions for a sequence of moment generating functions to converge to a moment generating function on an interval (a,b) not necessarily containing 0, is given. The result is derived using recent results by Mukherjea, ... More
Sets with High Volume and Low PerimeterJul 14 2011In this paper, we consider a certain variation of the "isoperimetric problem" adopted for subsets of nonnegative integers. More specifically, we explore the sequence P(n) as described in OEIS A186053. We provide the first exact formulas for P(n) including ... More
On the Art and Science of Machine Learning ExplanationsOct 05 2018This text discusses several explanatory methods that go beyond the error measurements and plots traditionally used to assess machine learning models. Some of the methods are tools of the trade while others are rigorously derived and backed by long-standing ... More
An L^1 Ergodic Theorem for Sparse Random SubsequencesDec 16 2008We prove an L^1 subsequence ergodic theorem for sequences chosen by independent random selector variables, thereby showing the existence of universally L^1-good sequences nearly as sparse as the set of squares. In the process, we prove that a certain ... More
Pointwise Convergence for Subsequences of Weighted AveragesNov 20 2009Sep 13 2011We prove that if $\mu_n$ are probability measures on $Z$ such that $\hat \mu_n$ converges to 0 uniformly on every compact subset of $(0,1)$, then there exists a subsequence $\{n_k\}$ such that the weighted ergodic averages corresponding to $\mu_{n_k}$ ... More
Soft matter in hard confinement: phase transition thermodynamics, structure, texture, diffusion and flow in nanoporous media - topical reviewFeb 16 2015Spatial confinement in nanoporous media affects the structure, thermodynamics and mobility of molecular soft matter often markedly. This article reviews thermodynamic equilibrium phenomena, such as physisorption, capillary condensation, crystallisation, ... More
Nrqed in Bound States: Applying Renormalization to an Effective Field TheorySep 22 1992This is a pedagogical introduction to NRQED, a low enery approximation of QED which can be made to reproduce QED to an arbitrary precision. It is especially useful when applied to nonrelativistic bound states. We start by explaining why QED is so difficult ... More
Relative hyperbolicity and right-angled Coxeter groupsJan 21 2004We show that right-angled Coxeter groups are relatively hyperbolic in the sense defined by Farb, relative to a natural collection of rank-2 parabolic subgroups.
Automorphisms of Coxeter groupsOct 09 2003We compute Aut(W) for any even Coxeter group whose Coxeter diagram is connected, contains no edges labeled 2, and cannot be separated into more than 2 connected components by removing a single vertex. The description is given explicitly in terms of the ... More
Still another approach to the braid orderingJun 24 2005We develop a new approach to the linear ordering of the braid group $B\_n$, based on investigating its restriction to the set $\Div(\Delta\_n^d)$ of all divisors of $\Delta\_n^d$ in the monoid $B\_\infty^+$, i.e., to positive $n$-braids whose normal form ... More
A New Well-posed Nonlocal Perona-Malik Type EquationFeb 23 2007A modification of the Perona-Malik equation is proposed for which the local nonlinear diffusion term is replaced by a nonlocal term of slightly reduced ``strength''. The new equation is globally well-posed (in spaces of classical regularity) and possesses ... More
Groupes de GarsideNov 13 2001Define a Garside monoid to be a cancellative monoid where right and left lcm's exist and that satisfy additional finiteness assumptions, and a Garside group to be the group of fractions of a Garside monoid. The family of Garside groups contains the braid ... More
Complete positive group presentationsNov 27 2001A combinatorial property of prositive group presentations, called completeness, is introduced, with an effective criterion for recognizing complete presentations, and an iterative method for completing an incomplete presentation. We show how to directly ... More
The group of parenthesized braidsJul 07 2004Jun 27 2005We investigate a group $B\_\bullet$ that includes Artin's braid group $B\_\infty$ and Thompson's group $F$. The elements of $B\_\bullet$ are represented by braids diagrams in which the distances between the strands are not uniform and, besides the usual ... More
2-step nilpotent Lie groups arising from semisimple modulesJun 17 2008Every finite dimensional real representation of a compact real semisimple Lie algebra determines a metric 2-step nilpotent Lie algebra and a corresponding simply connected metric 2-step nilpotent Lie group N. We study the differential geometry of N using ... More
Towards Quality of Experience Determination for Video in Augmented Binocular Vision ScenariosJun 04 2014Mar 04 2015With the continuous growth in the consumer markets of mobile smartphones and increasingly in augmented reality wearable devices, several avenues of research investigate the relationships between the quality perceived by mobile users and the delivery mechanisms ... More
Multiwavelength Observations of Pulsar Wind NebulaeAug 27 2010The extended nebulae formed as pulsar winds expand into their surroundings provide information about the composition of the winds, the injection history from the host pulsar, and the material into which the nebulae are expanding. Observations from across ... More
High resolution X-ray observations of 3C 58Nov 10 2003As the presumed remnant of SN1181, 3C 58 houses one of the youngest known neutron stars in the Galaxy. The properties of this young pulsar and its associated wind nebula differ considerably from those of the Crab, and may well offer a more typical example ... More
Trajectories of Rubber Balloons used in Balloon Releases: Theory and ApplicationMar 10 2011Balloon releases are one of the main attractions of many fairs. Helium filled rubber balloons are released to carry postcards over preferably long distances. Although such balloons have been considered in atmospheric sciences and air safety analysis, ... More
On the origin of non self-gravitating filaments in the ISMJun 23 2013{Filaments are ubiquitous in the interstellar medium as recently emphasized by Herschel, yet their physical origin remains elusive} {It is therefore important to understand the physics of molecular clouds to investigate how filaments form and what is ... More
Formation of low-mass stars and brown dwarfsApr 23 2012These lectures attempt to expose the most important ideas, which have been proposed to explain the formation of stars with particular emphasis on the formation of brown dwarfs and low-mass stars. We first describe the important physical processes which ... More
The Formation of Globular Cluster SystemsOct 26 2002I briefly review models for the formation of globular cluster systems, and summarize the observational properties (i.e., formation efficiencies, metallicity distributions, kinematics and ages) of the globular cluster systems of M87 and M49: two thoroughly ... More
On indecomposable trees in the boundary of Outer spaceFeb 16 2010May 25 2010Let $T$ be an $\mathbb{R}$-tree, equipped with a very small action of the rank $n$ free group $F_n$, and let $H \leq F_n$ be finitely generated. We consider the case where the action $F_n \curvearrowright T$ is indecomposable--this is a strong mixing ... More
Coherent Price Systems and Uncertainty-Neutral ValuationFeb 29 2012We consider fundamental questions of arbitrage pricing arising when the uncertainty model is given by a set of possible mutually singular probability measures. With a single probability model, essential equivalence between the absence of arbitrage and ... More
Testing Asteroseismology with red giants in eclipsing binary and multiple-star systemsNov 14 2013Red-giant stars are proving to be an incredible source of information for testing models of stellar evolution, as asteroseismology has opened up a window into their interiors. Such insights are a direct result of the unprecedented data from space missions ... More
Using the Zeldovich dynamics to test expansion schemesJun 18 2007Nov 29 2007We apply various expansion schemes that may be used to study gravitational clustering to the simple case of the Zeldovich dynamics. Using the well-known exact solution of the Zeldovich dynamics we can compare the predictions of these various perturbative ... More