Results for "Sandra V. Jeffers"

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No evidence for activity correlations in the radial velocities of Kapteyn's starJun 30 2015Stellar activity may induce Doppler variability at the level of a few m/s which can then be confused by the Doppler signal of an exoplanet orbiting the star. To first order, linear correlations between radial velocity measurements and activity indices ... More
Estimating magnetic filling factors from Zeeman-Doppler magnetogramsMar 13 2019Low-mass stars are known to have magnetic fields that are believed to be of dynamo origin. Two complementary techniques are principally used to characterise them. Zeeman-Doppler imaging (ZDI) can determine the geometry of the large-scale magnetic field ... More
Two planets around Kapteyn's star : a cold and a temperate super-Earth orbiting the nearest halo red-dwarfJun 03 2014Exoplanets of a few Earth masses can be now detected around nearby low-mass stars using Doppler spectroscopy. In this paper, we investigate the radial velocity variations of Kapteyn's star, which is both a sub-dwarf M-star and the nearest halo object ... More
Recovering planet radial velocity signals in the presence of starspot activity in fully convective starsDec 03 2016Accounting for stellar activity is a crucial component of the search for ever-smaller planets orbiting stars of all spectral types. We use Doppler imaging methods to demonstrate that starspot induced radial velocity variability can be effectively reduced ... More
Surprisingly different starspot distributions on the near equal-mass equal-rotation-rate stars in the M dwarf binary GJ 65 ABJun 13 2017We aim to understand how stellar parameters such as mass and rotation impact the distribution of starspots on the stellar surface. To this purpose, we have used Doppler imaging to reconstruct the surface brightness distributions of three fully convective ... More
Surprising detection of an equatorial dust lane on the AGB star IRC+10216Dec 16 2014Understanding the formation of planetary nebulae remains elusive because in the preceding asymtotic giant branch (AGB) phase these stars are heavily enshrouded in an optically thick dusty envelope. To further understand the morphology of the circumstellar ... More
Right marker speeds of solutions to the KPP equation with noiseJun 15 2018We consider the one-dimensional KPP-equation driven by space-time white noise. We show that for all parameters above the critical value for survival, there exist stochastic wavelike solutions which travel with a deterministic positive linear speed. We ... More
Comparaison entre cohomologie cristalline et cohomologie étale $p$-adique sur certaines variétés de ShimuraApr 11 2007Let $X$ be an integral model at a prime $p$ of a Shimura variety of PEL type having good reduction, associated to a reductive group $G$. To $\mathbb{Z}_p$ reprsententations of the group $G$ can be associated two kinds of sheaves : crystals on the special ... More
Travelling wave solutions to the KPP equation with branching noise arising from initial conditions with compact supportAug 04 2015We consider the one-dimensional KPP-equation driven by space-time white noise and extend the construction of travelling wave solutions arising from Heavyside initial data from [Tribe, 1996, MR1396765] to non-negative continuous functions with compact ... More
$\ell^2$-Linear Independence for the System of Integer Translates of a Square Integrable FunctionNov 09 2010Jan 07 2014We prove that if the system of integer translates of a square integrable function is $\ell^2$-linear independent then its periodization function is strictly positive almost everywhere. Indeed we show that the above inference is true for any square integrable ... More
Some remarks on the model of rigid heat conductor with memory: unbounded heat relaxation functionMar 25 2018The model of rigid linear heat conductor with memory is reconsidered focussing the interest on the heat relaxation function. Thus, the definitions of heat flux and thermal work are revised to understand where changes are required when the heat flux relaxation ... More
The CARMENES search for exoplanets around M dwarfs: A low-mass planet in the temperate zone of the nearby K2-18May 02 2018May 04 2018K2-18 is a nearby M2.5 dwarf, located at 34 pc and hosting a transiting planet which was first discovered by the {\it K2} mission and later confirmed with {\it Spitzer Space Telescope} observations. With a radius of $\sim 2 \, R_{\oplus}$ and an orbital ... More
A 3-dimensional singular kernel problem in viscoelasticity: an existence resultAug 07 2018Materials with memory, namely those materials whose mechanical and/or thermodynamical behaviour depends on time not only via the present time, but also through its past history, are considered. Specifically, a three dimensional viscoelastic body is studied. ... More
Radial velocity signatures of Zeeman broadeningJan 14 2013Stellar activity signatures such as spots and plage can significantly limit the search for extrasolar planets. Current models of activity-induced radial velocity (RV) signals focused on the impact of temperature contrast in spots predicting the signal ... More
The effects of stellar winds on the magnetospheres and potential habitability of exoplanetsSep 03 2014Context: The principle definition of habitability for exoplanets is whether they can sustain liquid water on their surfaces, i.e. that they orbit within the habitable zone. However, the planet's magnetosphere should also be considered, since without it, ... More
CARMENES input catalogue of M dwarfs II. High-resolution imaging with FastCamAug 29 2016Aims: We search for low-mass companions of M dwarfs and characterize their multiplicity fraction with the purpose of helping in the selection of the most appropriate targets for the CARMENES exoplanet survey. Methods: We obtained high-resolution images ... More
Studying stellar spin-down with Zeeman-Doppler magnetogramsMay 04 2017Magnetic activity and rotation are known to be intimately linked for low-mass stars. Understanding rotation evolution over the stellar lifetime is therefore an important goal within stellar astrophysics. In recent years, there has been increased focus ... More
Magnetic field and wind of Kappa Ceti: towards the planetary habitability of the young Sun when life arose on EarthMar 12 2016We report magnetic field measurements for Kappa1~Cet, a proxy of the young Sun when life arose on Earth. We carry out an analysis of the magnetic properties determined from spectropolarimetric observations and reconstruct its large-scale surface magnetic ... More
J band Variability of M Dwarfs in the WFCAM Transit SurveyNov 22 2012Dec 07 2012We present an analysis of the photometric variability of M dwarfs in the WFCAM Transit Survey. Although periodic lightcurve variability in low mass stars is generally dominated by photospheric star spot activity, M dwarf variability in the J band has ... More
A maximum entropy approach to detect close-in giant planets around active starsFeb 28 2015Oct 09 2015(shortened for arXiv) We aim to progress towards more efficient exoplanet detection around active stars by optimizing the use of Doppler Imaging in radial velocity measurements. We propose a simple method to simultaneously extract a brightness map and ... More
Logarithmic mean oscillation on the polydisc, endpoint results for multi-parameter paraproducts, and commutators on BMOJan 04 2012We study boundedness properties of a class of multiparameter paraproducts on the dual space of the dyadic Hardy space H_d^1(T^N), the dyadic product BMO space BMO_d(T^N). For this, we introduce a notion of logarithmic mean oscillation on the polydisc. ... More
Multilevel Adaptive Sparse Grid Quadrature for Monte Carlo modelsOct 01 2018Feb 15 2019Many problems require to approximate an expected value by some kind of Monte Carlo (MC) sampling, e.g. molecular dynamics (MD) or simulation of stochastic reaction models (also termed kinetic Monte Carlo (kMC)). Often, we are furthermore interested in ... More
Toric manifolds with degenerate dual variety and defect polytopesMay 09 2003Jun 12 2003We classify projective toric manifolds whose dual variety is not a hypersurface in the dual projective space. Under the standard dictionary between toric geometry and convex geometry, they correspond to certain convex Delzant integer polytopes, P, which ... More
Evolving phylogenies of trait-dependent branching with mutation and competition. Part I: ExistenceMay 09 2017We propose a type-dependent branching model with mutation and competition for modeling phylogenies of a virus population. The competition kernel depends for any two virus particles on the particles' types, the total mass of the population as well as genetic ... More
Existence of mark functions in marked metric measure spacesDec 05 2014Jun 27 2015We give criteria on the existence of a so-called mark function in the context of marked metric measure spaces (mmm-spaces). If an mmm-space admits a mark function, we call it functionally-marked metric measure space (fmm-space). This is not a closed property ... More
Studying the Earth with GeoneutrinosOct 15 2013Aug 29 2014Geo-neutrinos, electron antineutrinos from natural radioactive decays inside the Earth, bring to the surface unique information about our planet. The new techniques in neutrino detection opened a door into a completely new inter-disciplinary field of ... More
Schauder theorems for Ornstein-Uhlenbeck equations in infinite dimensionJan 06 2019We prove Schauder type estimates for stationary and evolution equations driven by the classical Ornstein-Uhlenbeck operator in a separable Banach space, endowed with a centered Gaussian measure.
SMOM - $\overline{MS}$ Matching for $B_K$ at Two-loop OrderJan 21 2019The Kaon bag parameter, $B_K$, is a key non-perturbative ingredient in the search for new physics through CP-violation. It parameterizes the QCD hadronic matrix element of the effective weak $\Delta S=2$ four-quark operator which can only be computed ... More
FutureGAN: Anticipating the Future Frames of Video Sequences using Spatio-Temporal 3d Convolutions in Progressively Growing GANsOct 02 2018Nov 26 2018We introduce a new encoder-decoder GAN model, FutureGAN, that predicts future frames of a video sequence conditioned on a sequence of past frames. During training, the networks solely receive the raw pixel values as an input, without relying on additional ... More
The CARMENES search for exoplanets around M dwarfs. Period search in H$α$, Na I D, and Ca II IRT linesJan 16 2019We use spectra from CARMENES, the Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs, to search for periods in chromospheric indices in 16 M0 to M2 dwarfs. We measure spectral indices in ... More
An algebraic proof of the commutativity of the intersection with divisorsJul 03 2007Dec 30 2007We present a purely algebraic proof of the commutativity of the operation defined by intersection with divisors on the Chow group of a local Noetherian domain.
Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicatorsOct 27 2017Context: The CARMENES survey is a high-precision radial velocity (RV) programme that aims to detect Earth-like planets orbiting low-mass stars. Aims: We develop least-squares fitting algorithms to derive the RVs and additional spectral diagnostics implemented ... More
The CARMENES search for exoplanets around M dwarfs: Radial-velocity variations of active stars in visual-channel spectraMar 06 2018Previous simulations predicted the activity-induced radial-velocity (RV) variations of M dwarfs to range from $\sim1$ cm/s to $\sim1$ km/s, depending on various stellar and activity parameters. We investigate the observed relations between RVs, stellar ... More
The CARMENES search for exoplanets around M dwarfs. Activity indicators at visible and near-infrared wavelengthsJan 25 2019The CARMENES survey is searching for Earth-like planets orbiting M dwarfs using the radial velocity method. Studying the stellar activity of the target stars is important to avoid false planet detections and to improve our understanding of the atmospheres ... More
The decomposition-coordination method for the $p(x)$-LaplacianJan 10 2014In this paper we construct two algorithms to approximate the minimizer of a discrete functional which comes from using a discontinuous Galerkin method for a variational problem related to the $p(x)$-Laplacian. We also make some numerical experiments in ... More
Explicit Evaluation of Certain Exponential Sums of Quadratic Functions over $\Bbb F_{p^n}$, $p$ OddAug 27 2007Let $p$ be an odd prime and let $f(x)=\sum_{i=1}^ka_ix^{p^{\alpha_i}+1}\in\Bbb F_{p^n}[x]$, where $0\le \alpha_1<...<\alpha_k$. We consider the exponential sum $S(f,n)=\sum_{x\in\Bbb F_{p^n}}e_n(f(x))$, where $e_n(y)=e^{2\pi i\text{Tr}_n(y)/p}$, $y\in\Bbb ... More
Sharp Bekolle estimates for the Bergman projectionOct 03 2012We prove sharp estimates for the Bergman projection in weighted Bergman spaces in terms of the Bekolle constant. Our main tools are a dyadic model dominating the operator and an adaptation of a method of Cruz-Uribe, Martell and Perez.
On the structure of $S_2$-ifications of complete local ringsJan 23 2014Motivated by work of Hochster and Huneke, we investigate several constructions related to the $S_2$-ification $T$ of a complete equidimensional local ring $R$: the canonical module, the top local cohomology module, topological spaces of the form $\operatorname{Spec}(R)-V(J)$, ... More
Superresolution method for data deconvolution by superposition of point sourcesMay 08 2018Dec 05 2018In this work we present a new algorithm for data deconvolution that allows the retrieval of the target function with super-resolution with a simple approach that after a precis e measurement of the instrument response function (IRF), the measured data ... More
The Rotationally Modulated Polarization of $ξ$ Boo ANov 21 2018Feb 10 2019We have observed the active star $\xi$ Boo A (HD 131156A) with high precision broadband linear polarimetry contemporaneously with circular spectropolarimetry. We find both signals are modulated by the 6.43 day rotation period of $\xi$ Boo A. The signals ... More
Magnetic fields on young, moderately rotating Sun-like stars - I: HD~35296 and HD~29615Feb 20 2015Observations of the magnetic fields of young solar-type stars provide a way to investigate the signatures of their magnetic activity and dynamos. Spectropolarimetry enables the study of these stellar magnetic fields and was thus employed at the T\'{e}lescope ... More
A Bcool spectropolarimetric survey of over 150 solar-type starsOct 24 2013As part of the Bcool project, over 150 solar-type stars chosen mainly from planet search databases have been observed between 2006 and 2013 using the NARVAL and ESPaDOnS spectropolarimeters on the Telescope Bernard Lyot (Pic du Midi, France) and the Canada ... More
The CARMENES search for exoplanets around M dwarfs. Chromospheric modeling of M2-3 V stars with PHOENIXFeb 11 2019Chromospheric modeling of observed differences in stellar activity lines is imperative to fully understand the upper atmospheres of late-type stars. We present one-dimensional parametrized chromosphere models computed with the atmosphere code PHOENIX ... More
The CARMENES search for exoplanets around M dwarfs: Nine new double-line spectroscopic binary starsAug 21 2018Context. The CARMENES spectrograph is surveying ~300 M dwarf stars in search for exoplanets. Among the target stars, spectroscopic binary systems have been discovered, which can be used to measure fundamental properties of stars. Aims. Using spectroscopic ... More
The CARMENES search for exoplanets around M dwarfs - The enigmatic planetary system GJ 4276: One eccentric planet or two planets in a 2:1 resonance?Jan 07 2019We report the detection of a Neptune-mass exoplanet around the M4.0 dwarf GJ 4276 (G 232-070) based on radial velocity (RV) observations obtained with the CARMENES spectrograph. The RV variations of GJ 4276 are best explained by the presence of a planetary ... More
The CARMENES search for exoplanets around M dwarfs: The warm super-Earths in twin orbits around the mid-type M dwarfs Ross 1020 (GJ 3779) and LP 819-052 (GJ 1265)Oct 17 2018We announce the discovery of two planetary companions orbiting around the low mass stars Ross 1020 (GJ 3779, M4.0V) and LP 819-052 (GJ 1265, M4.5V). The discovery is based on the analysis of CARMENES radial velocity observations in the visual channel ... More
The effect of M dwarf starspot activity on low-mass planet detection thresholdsNov 04 2010In light of the growing interest in searching for low mass, rocky planets, we investigate the impact of starspots on radial velocity searches for earth-mass planets in orbit about M dwarf stars. Since new surveys targeting M dwarfs will likely be carried ... More
Lightcurves for asteroids 18301 Konyukhov and 2022 WestJun 10 2018We report photometric analysis of two main-belt asteroids observed at the Observatorio Astronomico Nacional in the Sierra San Pedro Martir, Baja California, M\'exico. For 18301 Konyukhov our derived intrinsic rotation period is 2.6667 $\pm$ 0.0003 h with ... More
Goodness of fit tests in terms of local levels with special emphasis on higher criticism testsMar 17 2016Instead of defining goodness of fit (GOF) tests in terms of their test statistics, we present an alternative method by introducing the concept of local levels, which indicate high or low local sensitivity of a test. Local levels can act as a starting ... More
Bäcklund Transformations and Non-Abelian Nonlinear Evolution Equations: a Novel Bäcklund ChartDec 08 2015Aug 30 2016Classes of third order non-Abelian evolution equations linked to that of Korteweg-de Vries-type are investigated and their connections represented in a non-commutative B\"acklund chart, generalizing results in [Fuchssteiner B., Carillo S., Phys. A 154 ... More
A Liouville theorem for some Bessel generalized operatorsAug 18 2017Aug 22 2017In this paper we establish a Liouville theorem in $\mathcal{H'}_{\mu}$ for a wider class of operators in $(0,\infty)^{n}$ that generalizes the $n$-dimensional Bessel operator. We will present two different proofs, based in two representation theorems ... More
Asymptotic growth of powers of idealsOct 26 2006Let A be a locally analytically unramified local ring and let J_1,...,J_k,I be ideals in A. If C=C(J_1,...,J_k;I) is the cone generated by the (k+1)-tuples (m_1,...,m_k,n) such that J_1^{m_1}...J_k^{m_k} is contained in I^n, we prove that the topological ... More
Abelian versus non-Abelian Baecklund Charts: some remarksOct 03 2018Connections via Baecklund transformations among different non-linear evolution equations are investigated aiming to compare corresponding Abelian and non Abelian results. Specifically, links, via Baecklund transformations, connecting Burgers and KdV-type ... More
From $p_0(n)$ to $p_0(n+2)$Jul 13 2014Nov 06 2014In this note we study the global existence of small data solutions to the Cauchy problem for the semi-linear wave equation with a not effective scale-invariant damping term, namely \[ v_{tt}-\triangle v + \frac2{1+t}\,v_t = |v|^p, \qquad v(0,x)=v_0(x),\quad ... More
Reduction of Galois Representations of slope 1Apr 15 2015May 25 2018We compute the reductions of irreducible crystalline two-dimensional representations of $G_{\mathbf{Q}_p}$ of slope 1, for primes $p \geq 5$, and all weights. We describe the semisimplification of the reductions completely. In particular, we show that ... More
The effect of points fattening on Hirzebruch surfacesNov 13 2013The purpose of this note is to study initial sequences of zero-dimensional subschemes of Hirzebruch surfaces and classify subschemes whose initial sequence has the minimal possible growth.
Sarason Conjecture on the Bergman spaceApr 05 2013Sep 04 2013We provide a counterexample to the Sarason Conjecture for the Bergman space and present a characterisation of bounded Toeplitz products on the Bergman space in terms of test functions by means of a dyadic model approach. We also present some results about ... More
Almost global existence for exterior Neumann problems of semilinear wave equations in 2DAug 17 2012The aim of this article is to prove an "almost" global existence result for some semilinear wave equations in the plane outside a bounded convex obstacle with the Neumann boundary condition.
A note on higher order Gauss mapsOct 17 2014Oct 05 2016We study Gauss maps of order $k$, associated to a projective variety $X$ embedded in projective space via a line bundle $L.$ We show that if $X$ is a smooth, complete complex variety and $L$ is a $k$-jet spanned line bundle on $X$, with $k\geq 1,$ then ... More
Graphs Identified by Logics with CountingMar 30 2015We classify graphs and, more generally, finite relational structures that are identified by C2, that is, two-variable first-order logic with counting. Using this classification, we show that it can be decided in almost linear time whether a structure ... More
Applications of Laplace-Carleson embeddings to admissibility and controllabilityMar 12 2012It is shown how results on Carleson embeddings induced by the Laplace transform can be use to derive new and more general results concerning the weighted admissibility of control and observation operators for linear semigroup systems with q-Riesz bases ... More
Recursion Operators admitted by non-Abelian Burgers equations: Some RemarksJun 23 2016The recursion operators admitted by different operator Burgers equations, in the framework of the study of nonlinear evolution equations, are here con- sidered. Specifically, evolution equations wherein the unknown is an operator acting on a Banach space ... More
Optimal Collusion-Free TeachingMar 10 2019Formal models of learning from teachers need to respect certain criteria to avoid collusion. The most commonly accepted notion of collusion-freeness was proposed by Goldman and Mathias (1996), and various teaching models obeying their criterion have been ... More
Every zero-dimensional homogeneous space is strongly homogeneous under determinacyJun 01 2018All spaces are assumed to be separable and metrizable. We show that, assuming the Axiom of Determinacy, every zero-dimensional homogeneous space is strongly homogeneous (that is, all its non-empty clopen subspaces are homeomorphic), with the trivial exception ... More
An optimization problem with volume constrain for a degenerate quasilinear operatorFeb 17 2006We consider the optimization problem of minimizing $\int_{\Omega}|\nabla u|^p dx$ with a constrain on the volume of $\{u>0\}$. We consider a penalization problem, and we prove that for small values of the penalization parameter, the constrained volume ... More
The Impact of Age on Nationality Bias: Evidence from Ski JumpingAug 11 2018This empirical research explores the impact of age on nationality bias. World Cup competition data suggest that judges of professional ski jumping competitions prefer jumpers of their own nationality and exhibit this preference by rewarding them with ... More
LR-algebrasJan 08 2008In the study of NIL-affine actions on nilpotent Lie groups we introduced so called LR-structures on Lie algebras. The aim of this paper is to consider the existence question of LR-structures, and to start a structure theory of LR-algebras. We show that ... More
Sidechains and interoperabilityMar 10 2019There appears to be an insatiable desire for spawning new bespoke blockchains to harness the functionality provided by blockchain technologies, resulting in a constant stream of blockchain start-up companies entering the market with their own unique vision ... More
Asymptotic behavior of projections of supercritical multi-type continuous state and continuous time branching processes with immigrationJun 27 2018Under a fourth order moment condition on the branching and a second order moment condition on the immigration mechanisms, we show that an appropriately scaled projection of a supercritical and irreducible continuous state and continuous time branching ... More
Stable weakly shadowable volume-preserving systems are volume-hyperbolicJul 23 2012We prove that any C1-stably weakly shadowable volume-preserving diffeomorphism defined on a compact manifold displays a dominated splitting E + F. Moreover, both E and F are volume-hyperbolic. Finally, we prove the version of this result for divergence-free ... More
Connectedness and Lyubeznik numbersNov 10 2017We investigate the relationship between connectedness properties of spectra and the Lyubeznik numbers, numerical invariants defined via local cohomology. We prove that for complete equidimensional local rings, the Lyubeznik numbers characterize when connectedness ... More
Magnetic fields on young, moderately rotating Sun-like stars II. EK Draconis (HD 129333)Nov 23 2016The magnetic fields, activity and dynamos of young solar-type stars can be empirically studied using time-series of spectropolarimetric observations and tomographic imaging techniques such as Doppler imaging and Zeeman Doppler imaging. In this paper we ... More
Magnetic activity on AB Doradus: Temporal evolution of starspots and differential rotation from 1988 to 1994Oct 09 2006Surface brightness maps for the young K0 dwarf AB Doradus are reconstructed from archival data sets for epochs spanning 1988 to 1994. By using the signal-to-noise enhancement technique of Least-Squares Deconvolution, our results show a greatly increased ... More
The CARMENES search for exoplanets around M dwarfs. A Neptune-mass planet traversing the habitable zone around HD 180617Aug 03 2018Despite their activity, low-mass stars are of particular importance for the search of exoplanets by the means of Doppler spectroscopy, as planets with lower masses become detectable. We report on the discovery of a planetary companion around HD 180617, ... More
Detection of He I $\lambda10830$ Å absorption on HD 189733 b with CARMENES high-resolution transmission spectroscopyDec 06 2018We present three transit observations of HD 189733 b obtained with the high-resolution spectrograph CARMENES at Calar Alto. A strong absorption signal is detected in the near-infrared He I triplet at 10830 \AA{} in all three transits. During mid-transit, ... More
The Type II-Plateau Supernova 2017eaw in NGC 6946 and Its Red Supergiant ProgenitorMar 09 2019We present extensive optical photometric and spectroscopic observations, from 4 to 482 days after explosion, of the Type II-plateau (II-P) supernova (SN) 2017eaw in NGC 6946. SN 2017eaw is a normal SN II-P intermediate in properties between, for example, ... More
On the structure of defects in the Fe7Mo6 $μ$-PhaseFeb 04 2019Topologically close packed phases, among them the $\mu$-phase studied here, are commonly considered as being hard and brittle due to their close packed and complex structure. Nanoindentation enables plastic deformation and therefore investigation of the ... More
Direct Evidence for a Polar Spot on SV CamJan 31 2005We have used spectrophotometric data from the Hubble Space Telescope to eclipse-map the primary component of the RS CVn binary SV Cam over 9 HST orbits. We find from these observations and the HIPPARCOS parallax that the surface flux in the eclipsed low-latitude ... More
Bivariate Order PolynomialsJan 20 2019Motivated by Dohmen-P\"onitz-Tittmann's bivariate chromatic polynomial $\chi_G(x,y)$, which counts all $x$-colorings of a graph $G$ such that adjacent vertices get different colors if they are $\le y$, we introduce a bivarate version of Stanley's order ... More
Staying Alive - CPR Quality Parameters from Wrist-worn Inertial Sensor Data with Evolutionary Fitted Sinusoidal ModelsAug 31 2018Feb 15 2019In this paper, a robust sinusoidal model fitting method based on the Differential Evolution (DE) algorithm for determining cardiopulmonary resuscitation (CPR) quality-parameters - naming chest compression frequency and depth - as measured by an inertial ... More
Butterflies in a Semi-Abelian ContextApr 21 2011It is known that monoidal functors between internal groupoids in the category Grp of groups constitute the bicategory of fractions of the 2-category Grpd(Grp) of internal groupoids, internal functors and internal natural transformations in Grp with respect ... More
Lebesgue's Density Theorem and definable selectors for idealsNov 15 2018Nov 23 2018We introduce a notion of density point and prove results analogous to Lebesgue's density theorem for various well-known ideals on Cantor space and Baire space. In fact, we isolate a class of ideals for which our results hold. As a contrasting result of ... More
Estimating covariance functions of multivariate skew-Gaussian random fields on the sphereDec 10 2016Jul 26 2017This paper considers a multivariate spatial random field, with each component having univariate marginal distributions of the skew-Gaussian type. We assume that the field is defined spatially on the unit sphere embedded in $\mathbb{R}^3$, allowing for ... More
Compact and Efficient Representation of General Graph DatabasesDec 28 2018In this paper, we propose a compact data structure to store labeled attributed graphs based on the k2-tree, which is a very compact data structure designed to represent a simple directed graph. The idea we propose can be seen as an extension of the k2-tree ... More
Absolute absorption cross sections from photon recoil in a matter-wave interferometerFeb 21 2014Aug 13 2014We measure the absolute absorption cross section of molecules using a matter-wave interferometer. A nanostructured density distribution is imprinted onto a dilute molecular beam through quantum interference. As the beam crosses the light field of a probe ... More
Plasmon generation through electron tunneling in twisted double-layer graphene and metal-insulator-graphene systemsDec 25 2018Feb 26 2019The generation of highly-confined plasmons through far-field optical illumination appears to be impractical for technological applications due to their large energy-momentum mismatch with external light. Electrical generation of plasmons offers a possible ... More
Finite element approximation for the fractional eigenvalue problemMar 01 2016Apr 07 2018The purpose of this work is to study a finite element method for finding solutions to the eigenvalue problem for the fractional Laplacian. We prove that the discrete eigenvalue problem converges to the continuous one and we show the order of such convergence. ... More
The HARPS polarimeterOct 03 2010We recently commissioned the polarimetric upgrade of the HARPS spectrograph at ESO's 3.6-m telescope at La Silla, Chile. The HARPS polarimeter is capable of full Stokes spectropolarimetry with large sensitivity and accuracy, taking advantage of the large ... More
Hubble Space Telescope Observations of SV Cam: II. First Derivative Lightcurve Modelling using PHOENIX and ATLAS Model AtmospheresFeb 02 2006The variation of the specific intensity across the stellar disc is essential input parameter in surface brightness reconstruction techniques such as Doppler imaging, where the relative intensity contributions of different surface elements are important ... More
Plasmon Generation through Electron Tunneling in GrapheneJun 29 2017Aug 25 2017The short wavelength of graphene plasmons relative to the light wavelength makes them attractive for applications in optoelectronics and sensing. However, this property limits their coupling to external light and our ability to create and detect them. ... More
The Contagion Effects of Repeated Activation in Social NetworksMar 11 2017Demonstrations, protests, riots, and shifts in public opinion respond to the coordinating potential of communication networks. Digital technologies have turned interpersonal networks into massive, pervasive structures that constantly pulsate with information. ... More
Backbone decomposition of multitype superprocessesMar 26 2018In this paper, we provide a construction of the so-called backbone decomposition for multitype supercritical superprocesses. While backbone decompositions are fairly well-known for both continuous-state branching processes and superprocesses in the one-type ... More
Toric vector bundles and parliaments of polytopesSep 10 2014Feb 01 2017We introduce a collection of convex polytopes associated to a torus-equivariant vector bundle on a smooth complete toric variety. We show that the lattice points in these polytopes correspond to generators for the space of global sections and we relate ... More
Bounds and Prospects for Stable Multiply Charged Particles at the LHCDec 07 2018Colored and colorless particles that are stable on collider scales and carry exotic electric charges, so-called multiply-charged heavy stable particles (MCHSPs), exist in extensions of the Standard Model, and can include the top partner(s) in solutions ... More
Polyhedral adjunction theoryMay 12 2011Nov 02 2012In this paper we give a combinatorial view on the adjunction theory of toric varieties. Inspired by classical adjunction theory of polarized algebraic varieties we define two convex-geometric notions: the Q-codegree and the nef value of a rational polytope ... More
An Overview of Machine TeachingJan 18 2018In this paper we try to organize machine teaching as a coherent set of ideas. Each idea is presented as varying along a dimension. The collection of dimensions then form the problem space of machine teaching, such that existing teaching problems can be ... More
Compressed Sensing for Finite-Valued SignalsSep 29 2016The need of reconstructing discrete-valued sparse signals from few measurements, that is solving an undetermined system of linear equations, appears frequently in science and engineering. Whereas classical compressed sensing algorithms do not incorporate ... More
A Fast Gradient and Function Sampling Method for Finite Max-FunctionsAug 24 2017Sep 01 2017This paper tackles the unconstrained minimization of a class of nonsmooth and nonconvex functions that can be written as finite max-functions. A gradient and function-based sampling method is proposed which, under special circumstances, either moves superlinearly ... More
A terrestrial planet candidate in a temperate orbit around Proxima CentauriSep 12 2016At a distance of 1.295 parsecs, the red-dwarf Proxima Centauri ($\alpha$ Centauri C, GL 551, HIP 70890, or simply Proxima) is the Sun's closest stellar neighbor and one of the best studied low-mass stars. It has an effective temperature of only $\sim$ ... More
Data Reduction Techniques for High Contrast Imaging Polarimetry. Applications to ExPoMay 15 2011Imaging polarimetry is a powerful tool for detecting and characterizing exoplanets and circumstellar environments. Polarimetry allows a separation of the light coming from an unpolarized source such as a star and the polarized source such as a planet ... More