Results for "Kelsey R. Allen"

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Infinite Mixture Prototypes for Few-Shot LearningFeb 12 2019We propose infinite mixture prototypes to adaptively represent both simple and complex data distributions for few-shot learning. Our infinite mixture prototypes represent each class by a set of clusters, unlike existing prototypical methods that represent ... More
Few-Shot Bayesian Imitation Learning with Logic over ProgramsApr 12 2019We describe an expressive class of policies that can be efficiently learned from a few demonstrations. Policies are represented as logical combinations of programs drawn from a small domain-specific language (DSL). We define a prior over policies with ... More
Residual Policy LearningDec 15 2018Jan 03 2019We present Residual Policy Learning (RPL): a simple method for improving nondifferentiable policies using model-free deep reinforcement learning. RPL thrives in complex robotic manipulation tasks where good but imperfect controllers are available. In ... More
Spatial Linear Dark Field Control: Stabilizing Deep Contrast for Exoplanet Imaging Using Bright SpecklesMar 13 2017Sep 22 2017Direct imaging of exoplanets requires establishing and maintaining a high contrast dark field (DF) within the science image to a high degree of precision (10^-10). Current approaches aimed at establishing the DF, such as electric field conjugation (EFC), ... More
Star Formation via the Little Guy: A Bayesian Study of Ultracool Dwarf Imaging Surveys for CompanionsJul 13 2007I have undertaken a comprehensive statistical investigation of the ultracool dwarf companion distribution (spectral type M6 and later). Utilizing a Bayesian algorithm, I tested models of the companion distribution against data from an extensive set of ... More
Mathematical Modelling and Analysis of the Brassinosteroid and Gibberellin Signalling Pathways and their InteractionsMar 22 2017Aug 19 2017The plant hormones brassinosteroid (BR) and gibberellin (GA) have important roles in a wide range of processes involved in plant growth and development. In this paper we derive and analyse new mathematical models for the BR signalling pathway and for ... More
The Prevalence and Impact of Wolf-Rayet Stars in Emerging Massive Star ClustersMay 25 2016We investigate Wolf-Rayet (WR) stars as a source of feedback contributing to the removal of natal material in the early evolution of massive star clusters. Despite previous work suggesting that massive star clusters clear out their natal material before ... More
The importance of Wolf-Rayet ionization and feedback on super star cluster evolutionAug 03 2015The feedback from massive stars is important to super star cluster (SSC) evolution and the timescales on which it occurs. SSCs form embedded in thick material, and eventually, the cluster is cleared out and revealed at optical wavelengths -- however, ... More
Observational Limits on a Cold Distant Kuiper BeltSep 19 2002Almost all of the $>600$ known Kuiper belt objects (KBOs) have been discovered within 50 AU of the Sun. One possible explanation for the observed lack of KBOs beyond 50 AU is that the distant Kuiper belt is dynamically very cold, and thus thin enough ... More
The Edge of the Solar SystemNov 02 2000The population of the Kuiper Belt within 50 AU of the Sun has likely been severely depleted by gravitational perturbations from the giant planets, particularly Neptune. The density of Kuiper Belt objects is expected to be two orders of magnitude higher ... More
Dark Matter Equation of Motion and Density ProfilesJun 17 2001Cold dark matter simulations appear to disagree with the observations on small distance scales. Here we consider a modified description of CDM particles which is implied by a new fundamental theory: In this picture, the dark matter is composed of supersymmetric ... More
Spitzer-IRAC Search for Companions to Nearby, Young M DwarfsApr 17 2008We present the results of a survey of nearby, young M stars for wide low-mass companions with IRAC on the Spitzer Space Telescope. We observed 40 young M dwarfs within 20 pc of the Sun, selected through X-ray emission criteria. A total of 10 candidate ... More
Evidence for the Large-Scale Dissociation of Molecular Gas in the Inner Spiral Arms of M81Apr 22 1997We compare the detailed distributions of HI, H alpha, and 150 nm far-UV continuum emission in the spiral arms of M81 at a resolution of 9" (linear resolution 150 pc at 3.7 Mpc distance). The bright H alpha emission peaks are always associated with peaks ... More
Challenging a Newtonian prediction through Gaia wide binariesOct 19 2018Mar 07 2019Under Newtonian dynamics, the relative motion of the components of a binary star should follow a Keplerian scaling with separation. Once orientation effects and a distribution of ellipticities are accounted for, dynamical evolution can be modelled to ... More
Sea-level projections representing deeply uncertain ice-sheet contributionsSep 22 2016Future sea-level rise poses nontrivial risks for many coastal communities. Managing these risks often relies on consensus projections like those provided by the IPCC. Yet, there is a growing awareness that the surrounding uncertainties may be much larger ... More
Perfect Diffraction with Bianisotropic MetagratingsFeb 05 2018One highly desirable function of a diffraction grating is its ability to deflect incident light into a specific diffraction order with near-perfect efficiency. While such asymmetry can be achieved in a variety of ways, e.g., by using a sawtooth (blazed) ... More
Terahertz-induced depletion of the ground-state population of neutral donors in GaAs measured by resonant elastic light scattering from donor-bound excitonsMar 05 2005Strong resonant elastic light scattering (RELS) from the donor-bound exciton transition in GaAs (1.514eV) occurs at neutral donors in the ground (1S) state, but not at neutral donors in excited hydrogenic states. When 1.6 THz radiation is incident on ... More
Cepheid and SNIa Distance ScalesFeb 26 2001We first discuss why there remains continuing, strong motivation to investigate Hubble's Constant. Then we review new evidence from an investigation of the Galactic Open Clusters containing Cepheids by Hoyle et al. that the metallicity dependence of the ... More
Age-at-harvest models as monitoring and harvest management tools for Wisconsin carnivoresNov 15 2018Quantifying and estimating wildlife population sizes is a foundation of wildlife management. However, many carnivore species are cryptic, leading to innate difficulties in estimating their populations. We evaluated the potential for using more rigorous ... More
Cactus: Issues for Sustainable Simulation SoftwareSep 07 2013Sep 16 2013The Cactus Framework is an open-source, modular, portable programming environment for the collaborative development and deployment of scientific applications using high-performance computing. Its roots reach back to 1996 at the National Center for Supercomputer ... More
HST Images Do Not Support the Presence of Three High Velocity, Low-Mass Stars in the Core of the Orion Nebula ClusterOct 04 2005A recent article has employed the determination from groundbased images of high proper motions in the Orion Nebula Cluster to argue that JW 349, JW 355, and JW 451 are high velocity (38 km/s, 89 km/s, and 69 km/s, respectively) low mass runaway stars. ... More
Cepheid, Tully-Fisher and SNIa DistancesAug 12 2002We first discuss why the uncomfortable fine-tuning of the parameters of the Lambda-CDM cosmological model provides continuing, strong motivation to investigate Hubble's Constant. Then we review evidence from the HST Key Project that there is a significant ... More
On the dynamical evolution of the Orion TrapeziumJan 12 2017We discuss recent observational data on the transverse and radial velocities, as well as on the masses of the main components of the Orion Trapezium. Based on the most reliable values of these quantities we study the dynamical evolution of ensembles of ... More
Probabilistic Kernel Support Vector MachinesApr 14 2019We propose a probabilistic enhancement of standard {\em kernel Support Vector Machines} for binary classification, in order to address the case when, along with given data sets, a description of uncertainty (e.g., error bounds) may be available on each ... More
Interactions for odd-omega gap singlet superconductorsJun 10 1992Aug 16 1995A class of singlet superconductors with a gap function $\Delta({\bf k}, \omega_n)$ which is {\it odd} in both momentum and Matsubara frequency was proposed recently \cite{ba}. To show an instability in the {\it odd} gap channel, a model phonon propagator ... More
Evolutionary Method for Predicting Surface Reconstructions with Variable StoichiometryJan 24 2013May 02 2013We present a specially designed evolutionary algorithm for the prediction of surface reconstructions. This new technique allows one to automatically explore all the low-energy configurations with variable surface atoms and variable surface unit cells ... More
On vertex, edge, and vertex-edge random graphsDec 08 2008Oct 13 2010We consider three classes of random graphs: edge random graphs, vertex random graphs, and vertex-edge random graphs. Edge random graphs are Erdos-Renyi random graphs, vertex random graphs are generalizations of geometric random graphs, and vertex-edge ... More
Density-Functional-Based Determination of Vibrational Polarizabilities in MoleculesOct 05 2004Oct 29 2004We develop a direct derivation for the primary contribution to the vibrational polarizability for molecules, clusters and other finite systems. The vibrational polarizability is then calculated within the generalized gradient approximation to the density ... More
Surface Phonons and Other Localized ExcitationsAug 13 1999The diatomic linear chain of masses coupled by harmonic springs is a textboook model for vibrational normal modes (phonons) in crystals. In addition to propagating acoustic and optic branches, this model is known to support a ``gap mode'' localized at ... More
Mapping schemes realizable by obstructed topological polynomialsMay 26 2010Jan 27 2011In 1985, Levy used a theorem of Berstein to prove that all hyperbolic topological polynomials are equivalent to complex polynomials. We prove a partial converse to the Berstein-Levy Theorem: given post-critical dynamics that are in a sense strongly non-hyperbolic, ... More
Direct evidence of hierarchical assembly at low masses from isolated dwarf galaxy groupsJan 06 2017The demographics of dwarf galaxy populations have long been in tension with predictions from the Cold Dark Matter (CDM) paradigm. If primordial density fluctuations were scale-free as predicted, dwarf galaxies should themselves host dark matter subhaloes, ... More
New Low-Mass Stars and Brown Dwarfs with Disks in LupusFeb 16 2007Using the Infrared Array Camera and the Multiband Imaging Photometer aboard the {\it Spitzer Space Telescope}, we have obtained images of the Lupus 3 star-forming cloud at 3.6, 4.5, 5.8, 8.0, and 24 \micron. We present photometry in these bands for the ... More
The Vertical Dust Structure in Spiral DisksJan 18 2008The halo of NGC 891 has been the subject of studies for more than a decade. One of its most striking features is the large asymmetry in H-$\alpha$ emission. We have taken a quantitative look at this asymmetry at different wavelengths for the first time. ... More
Quantifying the Value of Real-time Geodetic Constraints for Earthquake Early Warning using a Global Seismic and Geodetic DatasetJan 30 2019Geodetic earthquake early warning (EEW) algorithms complement point-source seismic systems by estimating fault-finiteness and unsaturated moment magnitude for the largest, most damaging earthquakes. Because such earthquakes are rare, it has been difficult ... More
Cosmic Microwave Background Radiation Anisotropy Induced by Cosmic StringsJul 14 1994We report on a current investigation of the anisotropy pattern induced by cosmic strings on the cosmic microwave background radiation (MBR). We have numerically evolved a network of cosmic strings from a redshift of $Z = 100$ to the present and calculated ... More
DFT Calculations of Temperature-Dependent NQR Parameters in α-paradichlorobenzene and β-HMXMar 25 2019A method for first principles predictions of observed temperature-dependent NQR spectra is presented using density functional theory (DFT) and the isobaric T-dependent NQR frequencies of 35Cl and 14N nuclei are computed for the two molecular crystals ... More
Cannibalization and Rebirth in the NGC5387 System. I. The Stellar Stream & Star Forming RegionDec 02 2013We have identified a low surface brightness stellar stream from visual inspection of SDSS imaging for the edge-on, spiral galaxy NGC5387. A blue overdensity was also identified in SDSS coincident with the stream intersection with the NGC5387 disk. The ... More
The Size Distribution of Trans-Neptunian BodiesAug 26 2003Jun 14 2004[Condensed] We search 0.02 deg^2 for trans-Neptunian objects (TNOs) with m<=29.2 (diameter ~15 km) using the ACS on HST. Three new objects are discovered, roughly 25 times fewer than expected from extrapolation of the differential sky density Sigma(m) ... More
The Disk Population of the Chamaeleon I Star-Forming RegionMar 07 2008We present a census of circumstellar disks in the Chamaeleon I star-forming region. Using the Infrared Array Camera and the Multiband Imaging Photometer onboard the Spitzer Space Telescope, we have obtained images of Chamaeleon I at 3.6, 4.5, 5.8, 8.0, ... More
A Fractional Free Boundary Problem Related to a Plasma ProblemJul 22 2015We study a fractional analogue of a plasma problem arising from physics. Specifically, for a fixed bounded domain $\Omega$ we study solutions to the eigenfunction equation \[ (- \Delta)^s u = \lambda(u- \gamma)_+ \] with $u \equiv 0$ on $\partial \Omega$. ... More
Gauge Invariant Uniqueness Theorem for Corners of k-graphsJun 29 2005For a finitely aligned k-graph $\Lambda$ with X a set of vertices in $\Lambda$ we define a universal C*-algebra called $C^*(\Lambda,X)$ generated by partial isometries. We show that $C^*(\Lambda,X)$ is isomorphic to the corner $P_XC^*(\Lambda)P_X$, where ... More
Randomly juggling backwardsJan 24 2016We recall the directed graph of _juggling states_, closed walks within which give juggling patterns, as studied by Ron Graham in [w/Chung, w/Butler]. Various random walks in this graph have been studied before by several authors, and their equilibrium ... More
The Category-Theoretic Arithmetic of InformationMar 25 2008Jul 21 2008We highlight the underlying category-theoretic structure of measures of information flow. We present an axiomatic framework in which communication systems are represented as morphisms, and information flow is characterized by its behavior when communication ... More
Holder Regularity for Nondivergence nonlocal parabolic equationsOct 31 2016May 14 2018This paper proves H\"older continuity of viscosity solutions to certain nonlocal parabolic equations that involve a generalized fractional time derivative of Marchaud or Caputo type. As a necessary and preliminary result, this paper first shows that viscosity ... More
Puzzles, positroid varieties, and equivariant K-theory of GrassmanniansAug 25 2010Vakil studied the intersection theory of Schubert varieties in the Grassmannian in a very direct way: he degenerated the intersection of a Schubert variety X_mu and opposite Schubert variety X^nu to a union {X^lambda}, with repetition. This degeneration ... More
A Schubert calculus recurrence from the noncomplex W-action on G/BJun 20 2003In this paper, as in our previous "Descent-cycling in Schubert calculus" math.CO/0009112, we study the structure constants in equivariant cohomology of flag manifolds G/B. In this one we give a recurrence (which is frequently, but alas not always, positive) ... More
Frobenius splitting, point-counting, and degenerationNov 25 2009Let f be a polynomial of degree n in ZZ[x_1,..,x_n], typically reducible but squarefree. From the hypersurface {f=0} one may construct a number of other subschemes {Y} by extracting prime components, taking intersections, taking unions, and iterating ... More
Automatically reduced degenerations of automatically normal varietiesSep 25 2007Let F be a flat family of projective schemes, whose geometric generic fiber is reduced and irreducible. We give conditions on a special fiber (a "limit" of the family) to guarantee that it too is reduced. These conditions often imply also that the generic ... More
Local Volume TiNy Titans: Gaseous Dwarf-Dwarf Interactions in the Local UniverseMar 30 2016Apr 01 2016In this paper, we introduce the Local Volume TiNy Titans sample (LV-TNT), which is a part of a larger body of work on interacting dwarf galaxies: TNT (Stierwalt et al. 2015). This LV-TNT sample consists of 10 dwarf galaxy pairs in the Local Universe (< ... More
Discovery of a low-eccentricity, high-inclination Kuiper belt object at 58 AUDec 16 2005We report the discovery of the first trans-neptunian object, designated 2004 XR190, with a nearly-cirular orbit beyond the 2:1 mean-motion resonance. Fitting an orbit to 23 astrometric observations spread out over 12 months yields an orbit of a=57.2\pm0.4, ... More
The Opacity of Spiral Galaxy Disks VII: the accuracy of galaxy counts as an extinction probeAug 02 2005The ``Synthetic Field Method'' (SFM) was introduced by Gonzalez et al. (1998) to calibrate numbers of distant galaxies as a probe of extinction in a foreground spiral disk. Gonzalez et al. (2003) studied the effect of the foreground disk on these numbers ... More
The Opacity of Spiral Galaxy Disks V: dust opacity, HI distributions and sub-mm emissionAug 02 2005The opacity of spiral galaxy disks, from counts of distant galaxies, is compared to HI column densities. The opacity measurements are calibrated using the ``Synthetic Field Method'' from Gonzalez et al (1998) and Holwerda et al. (2005a). When compared ... More
The Shape of Dark Matter Haloes II. The Galactus HI Modelling & Fitting ToolAug 19 2016We present a new HI modelling tool called \textsc{Galactus}. The program has been designed to perform automated fits of disc-galaxy models to observations. It includes a treatment for the self-absorption of the gas. The software has been released into ... More
Atomic Hydrogen produced in M33 Photodissociation RegionsFeb 23 2011We derive total (atomic + molecular) hydrogen densities in giant molecular clouds (GMCs) in the nearby spiral galaxy M33 using a method that views the atomic hydrogen near regions of recent star formation as the product of photodissociation. Far-UV photons ... More
Discovery of a Wide Binary Brown Dwarf Born in IsolationFeb 03 2009Jul 21 2010During a survey for stars with disks in the Taurus star-forming region using the Spitzer Space Telescope, we have discovered a pair of young brown dwarfs, FU Tau A and B, in the Barnard 215 dark cloud. They have a projected angular separation of 5.7", ... More
Schubert calculus and shifting of interval positroid varietiesAug 06 2014Consider k x n matrices with rank conditions placed on intervals of columns. The ranks that are actually achievable correspond naturally to upper triangular partial permutation matrices, and we call the corresponding subvarieties of Gr(k,n) the _interval ... More
Positive formulae for K-types of SL_3(R)-irreps and a Blattner formula for smooth K-orbit closuresSep 30 2014Oct 06 2014We prove a version of Blattner's conjecture, for irreducible subquotients of principal series representations with integral infinitesimal character of a real reductive Lie group whose Beilinson-Bernstein D-module is supported on a K-orbit with smooth ... More
Schur indices in GAP: wedderga 4.6+Jul 16 2014We describe a algorithms and their implementations that calculate local and global Schur indices of ordinary irreducible characters of finite groups, cyclotomic algebras over abelian number fields, and rational quaternion algebras. These functions are ... More
Balanced normal cones and Fulton-MacPherson's intersection theoryDec 29 2005Let X be a subscheme of a reduced scheme Y. Then Y has a flat "degeneration to the normal cone" C_X Y of X, and this degeneration plays a key step in Fulton and MacPherson's "basic construction" in intersection theory. The intersection product has a canonical ... More
A free boundary problem on three-dimensional conesApr 17 2017We consider a free boundary problem on cones depending on a parameter c and study when the free boundary is allowed to pass through the vertex of the cone. We show that when the cone is three-dimensional and c is large enough, the free boundary avoids ... More
Dense H-free graphs are almost (χ(H)-1)-partiteJul 22 2009Feb 16 2011By using the Szemer\'edi Regularity Lemma, Alon and Sudakov recently extended the classical Andr\'asfai-Erd\~os-S\'os theorem to cover general graphs. We prove, without using the Regularity Lemma, that the following stronger statement is true. Given any ... More
Center-Excised X-ray Luminosity as an Efficient Mass Proxy for Future Galaxy Cluster SurveysMay 25 2017Oct 26 2017The cosmological constraining power of modern galaxy cluster catalogs can be improved by obtaining low-scatter mass proxy measurements for even a small fraction of sources. In the context of large upcoming surveys that will reveal the cluster population ... More
A search for binary systems among the nearest L dwarfsJun 13 2006We have used the NICMOS NIC1 camera on the Hubble Space Telescope to obtain high angular resolution images of 51 ultracool dwarfs in the immediate Solar Neighbourhood. Nine systems are resolved as binary, with component separations from 1.5 and 15 AU. ... More
The Millennium Galaxy Catalogue: Dynamically Close Galaxy Pairs and the Global Merger RateJun 27 2005We derive the number of dynamically close companions per galaxy ($N_c$) and their total luminosity ($L_c$) for galaxies in the Millennium Galaxy Catalogue: $N_c$ is similar to the fraction of galaxies in close pairs and is directly related to the galaxy ... More
Low-Mass Tertiary Companions to Spectroscopic Binaries I: Common Proper Motion Survey for Wide Companions using 2MASSJun 19 2012We report the first results of a multi-epoch search for wide (separations greater than a few tens of AU), low-mass tertiary companions of a volume-limited sample of 118 known spectroscopic binaries within 30 pc of the Sun, using the 2MASS Point Source ... More
The Substellar Mass Function: A Bayesian ApproachFeb 09 2005We report our efforts to constrain the form of the low-mass star and brown dwarf mass function via Bayesian inference. Recent surveys of M, L, and T dwarfs in the local solar neighborhood are an essential component of our study. Uncertainties in the age ... More
Faster Algorithms for the Geometric Transportation ProblemMar 19 2019Let $R$ and $B$ be two point sets in $\mathbb{R}^d$, with $|R|+ |B| = n$ and where $d$ is a constant. Next, let $\lambda : R \cup B \to \mathbb{N}$ such that $\sum_{r \in R } \lambda(r) = \sum_{b \in B} \lambda(b)$ be demand functions over $R$ and $B$. ... More
Local Compressibility Measurements of Correlated States in Suspended Bilayer GrapheneSep 10 2010Bilayer graphene has attracted considerable interest due to the important role played by many-body effects, particularly at low energies. Here we report local compressibility measurements of a suspended graphene bilayer. We find that the energy gaps at ... More
Some schemes related to the commuting varietyJun 18 2003The_commuting variety_ is the pairs of NxN matrices (X,Y) such that XY = YX. We introduce the_diagonal commutator scheme_, {(X,Y) : XY-YX is diagonal}, which we prove to be a reduced complete intersection, one component of which is the commuting variety. ... More
Uniqueness for weak solutions of parabolic equations with a fractional time derivativeMay 10 2017Jan 02 2018We prove uniqueness for weak solutions to abstract parabolic equations with the fractional Marchaud or Caputo time derivative. We consider weak solutions in time for divergence form equations when the fractional derivative is transferred to the test function. ... More
A Nondivergence Parabolic Problem with a Fractional Time derivativeJul 15 2015May 03 2017We study a nonlocal nonlinear parabolic problem with a fractional time derivative. We prove a Krylov-Safonov type result; mainly, we prove Holder regularity of solutions. Our estimates remain uniform as the order of the fractional time derivative approaches ... More
Regularity of solutions for a free boundary problem in two dimensionsMar 31 2016Apr 17 2017We study the regularity of minimizers to the functional \[ J(w)=\int_{\Omega} a^{ij}w_iw_j + Q\chi_{\{w>0\}}, \] over a bounded domain $\Omega$ and among the class of nonnegative functions in $W^{1,2}(\Omega)$ with prescribed boundary data. We assume ... More
Early-type galaxies with core collapse supernovaeJun 26 2008It is widely accepted that the progenitors of core collapse SNe are young massive stars and therefore their host galaxies are mostly spiral or irregular galaxies dominated by a young stellar population. Surprisingly, among morphologically classified hosts ... More
The Sun was not born in M 67Jan 04 2012Using the most recent proper-motion determination of the old, Solar-metallicity, Galactic open cluster M 67, in orbital computations in a non-axisymmetric model of the Milky Way, including a bar and 3D spiral arms, we explore the possibility that the ... More
Absolute proper motion of the Galactic open cluster M67May 05 2010We derived the absolute proper motion (PM) of the old, solar-metallicity Galactic open cluster M67 using observations collected with CFHT (1997) and with LBT (2007). About 50 galaxies with relatively sharp nuclei allow us to determine the absolute PM ... More
An Infrared/X-ray Survey for New Members of the Taurus Star-Forming RegionNov 29 2009We present the results of a search for new members of the Taurus star-forming region using data from the Spitzer Space Telescope and the XMM-Newton Observatory. We have obtained optical and near-infrared spectra of 44 sources that exhibit red Spitzer ... More
A New Brown Dwarf Desert? A Scarcity of Wide Ultracool BinariesOct 25 2006We present the results of a deep-imaging search for wide companions to low-mass stars and brown dwarfs using NSFCam on IRTF. We searched a sample of 132 M7-L8 dwarfs to magnitude limits of $J \sim 20.5$ and $K \sim 18.5$, corresponding to secondary-primary ... More
The Millennium Galaxy Catalogue: a census of local compact galaxiesApr 10 2006We use the Millennium Galaxy Catalogue (MGC) to study the effect of compact galaxies on the local field galaxy luminosity function. Here we observationally define as `compact' galaxies that are too small to be reliably distinguished from stars using a ... More
Coulomb-driven broken-symmetry states in doubly gated suspended bilayer grapheneOct 05 2010The non-interacting energy spectrum of graphene and its bilayer counterpart consists of multiple degeneracies owing to the inherent spin, valley and layer symmetries. Interactions among charge carriers are expected to spontaneously break these symmetries, ... More
Visual boundaries of Diestel-Leader graphsJul 08 2013May 28 2015Diestel-Leader graphs are neither hyperbolic nor CAT(0), so their visual boundaries may be pathological. Indeed, we show that for $d>2$, $\partial\text{DL}_d(q)$ carries the indiscrete topology. On the other hand, $\partial\text{DL}_2(q)$, while not Hausdorff, ... More
Planet Four: Terrains - Discovery of Araneiforms Outside of the South Polar Layered DepositsAug 25 2017We present the results of a systematic mapping of seasonally sculpted terrains on the South Polar region of Mars with the Planet Four: Terrains (P4T) online citizen science project. P4T enlists members of the general public to visually identify features ... More
The Disk Population of the Taurus Star-Forming RegionNov 29 2009Jul 21 2010We have analyzed nearly all images of the Taurus star-forming region at 3.6-24um that were obtained during the cryogenic mission of the Spitzer Space Telescope (46 deg^2) and have measured photometry for all known members of the region that are within ... More
Luminosity Functions of Young Clusters: Modeling the Substellar Mass RegimeJun 16 2003We predict near-infrared luminosity functions of young (5 Myr to 1 Gyr) star clusters by combining evolutionary models of very low-mass ($1 M_J$ to $0.15 M_{\odot}$) dwarfs with empirical bolometric corrections. We identify several characteristic features ... More
The Frequency of Dwarf Galaxy Multiples at Low Redshift in SDSS vs. Cosmological ExpectationsJul 17 2018We quantify the frequency of companions of low redshift ($0.013 < z < 0.0252$), dwarf galaxies ($2 \times 10^8$ M$_\odot <$ M$_{*} < 5 \times 10^9$ M$_\odot$) that are isolated from more massive galaxies in SDSS and compare against cosmological expectations ... More
Time-resolved double-slit experiment with entangled photonsApr 17 2013May 06 2013The double-slit experiment strikingly demonstrates the wave-particle duality of quantum objects. In this famous experiment, particles pass one-by-one through a pair of slits and are detected on a distant screen. A distinct wave-like pattern emerges after ... More
Optical and mechanical design of the extreme AO coronagraphic instrument MagAO-XJul 11 2018Here we review the current optical mechanical design of MagAO-X. The project is post-PDR and has finished the design phase. The design presented here is the baseline to which all the optics and mechanics have been fabricated. The optical/mechanical performance ... More
Relational inductive biases, deep learning, and graph networksJun 04 2018Oct 17 2018Artificial intelligence (AI) has undergone a renaissance recently, making major progress in key domains such as vision, language, control, and decision-making. This has been due, in part, to cheap data and cheap compute resources, which have fit the natural ... More
G 112-29 (=NLTT 18149), a Very Wide Companion to GJ 282 AB with a Common Proper Motion, Common Parallax, Common Radial Velocity and Common AgeOct 15 2009We have made a search for common proper motion (CPM) companions to the wide binaries in the solar vicinity. We found that the binary GJ 282AB has a very distant CPM companion (NLTT 18149) at a separation $s=1.09 \arcdeg$. Improved spectral types and radial ... More
Predicting the dynamics of bacterial growth inhibition by ribosome-targeting antibioticsJan 13 2017Understanding how antibiotics inhibit bacteria can help to reduce antibiotic use and hence avoid antimicrobial resistance - yet few theoretical models exist for bacterial growth inhibition by a clinically relevant antibiotic treatment regimen. In particular, ... More
Relational inductive bias for physical construction in humans and machinesJun 04 2018While current deep learning systems excel at tasks such as object classification, language processing, and gameplay, few can construct or modify a complex system such as a tower of blocks. We hypothesize that what these systems lack is a "relational inductive ... More
Realization of a Large-Acceptance Faraday Cup for 3 MeV ElectronsNov 27 2018The design, construction, installation, and testing of a Faraday Cup intended to measure the current of a 3 MeV, 1 microampere electron beam is described. Built as a current monitor for a M{\o}ller scattering measurement at the MIT High Voltage Research ... More
Weighing the Giants II: Improved Calibration of Photometry from Stellar Colors and Accurate Photometric RedshiftsAug 02 2012Apr 19 2014We present improved methods for using stars found in astronomical exposures to calibrate both star and galaxy colors as well as to adjust the instrument flat field. By developing a spectroscopic model for the SDSS stellar locus in color-color space, synthesizing ... More
Weighing the Giants - I. Weak-lensing masses for 51 massive galaxy clusters: project overview, data analysis methods and cluster imagesAug 02 2012Apr 18 2014This is the first in a series of papers in which we measure accurate weak-lensing masses for 51 of the most X-ray luminous galaxy clusters known at redshifts 0.15<z<0.7, in order to calibrate X-ray and other mass proxies for cosmological cluster experiments. ... More
Robust Weak-lensing Mass Calibration of Planck Galaxy ClustersFeb 11 2014Oct 09 2014In light of the tension in cosmological constraints reported by the Planck team between their SZ-selected cluster counts and Cosmic Microwave Background (CMB) temperature anisotropies, we compare the Planck cluster mass estimates with robust, weak-lensing ... More
Revealing the properties of dark matter in the merging cluster MACSJ0025.4-1222Jun 13 2008Jul 23 2008We constrain the physical nature of dark matter using the newly identified massive merging galaxy cluster MACSJ0025.4-1222. As was previously shown by the example of the Bullet Cluster (1E0657-56), such systems are ideal laboratories for detecting isolated ... More
Electronic Structure of ZnO nanowireSep 29 2006This paper presents two first-principles calculations on the lattice- and electronic- structures of a small-diameter infinite and truncated ZnO nanowire. The two calculations show excellent agreement with each other. For the small diameter nanowire, the ... More
The Millennium Galaxy Catalogue: The connection between close pairs and asymmetry; implications for the galaxy merger rateMay 17 2007We compare the use of galaxy asymmetry and pair proximity for measuring galaxy merger fractions and rates for a volume limited sample of 3184 galaxies with -21 < M(B) -5 log h < -18 mag. and 0.010 < z < 0.123 drawn from the Millennium Galaxy Catalogue. ... More
Cosmology and Astrophysics from Relaxed Galaxy Clusters I: Sample SelectionFeb 20 2015This is the first in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Here we present a new, automated method for identifying relaxed clusters based on their morphologies in X-ray imaging data. ... More
Weighing the Giants - III. Methods and Measurements of Accurate Galaxy Cluster Weak-Lensing MassesAug 02 2012Apr 18 2014We report weak-lensing masses for 51 of the most X-ray luminous galaxy clusters known. This cluster sample, introduced earlier in this series of papers, spans redshifts 0.15 < z_cl < 0.7, and is well suited to calibrate mass proxies for current cluster ... More
BEC-BCS crossover in a cold and magnetized two color NJL modelOct 08 2015Jan 23 2016The BEC-BCS crossover for a NJL model with diquark interactions is studied in the presence of an external magnetic field. Particular attention is paid to different regularization schemes used in the literature. A thorough comparison of results is performed ... More