Results for "Sandra V. Jeffers"

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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
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
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
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
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
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
Evaluating Word Embeddings for Sentence Boundary Detection in Speech TranscriptsAug 15 2017This paper is motivated by the automation of neuropsychological tests involving discourse analysis in the retellings of narratives by patients with potential cognitive impairment. In this scenario the task of sentence boundary detection in speech transcripts ... More
A BCool survey of the magnetic fields of planet-hosting solar-type starsNov 23 2016We present a spectropolarimetric snapshot survey of solar-type planet hosting stars. In addition to 14 planet-hosting stars observed as part of the BCool magnetic snapshot survey, we obtained magnetic observations of a further 19 planet-hosting solar-type ... More
A compact containment result for nonlinear historical superprocess approximations for population models with trait-dependenceMay 05 2014Dec 05 2014We consider an approximating sequence of interacting population models with branching, mutation and competition. Each individual is characterized by its trait and the traits of its ancestors. Birth- and death-events happen at exponential times. Traits ... More
On the locus of $2$-dimensional crystalline representations with a given reduction modulo $p$May 02 2017Jun 30 2018We consider the family of irreducible crystalline representations of dimension $2$ of ${\rm Gal}(\overline{\bf Q}_p/{\bf Q}_p)$ given by the $V_{k,a_p}$ for a fixed weight integer $k\geq 2$. We study the locus of the parameter $a_p$ where these representations ... More
The Solar Wind in Time II: 3D stellar wind structure and radio emissionNov 13 2018In this work, we simulate the evolution of the solar wind along its main sequence lifetime and compute its thermal radio emission. To study the evolution of the solar wind, we use a sample of solar mass stars at different ages. All these stars have observationally-reconstructed ... More
The Evolving Magnetic Topology of $τ$ BoötisApr 08 2016We present six epochs of spectropolarimetric observations of the hot-Jupiter-hosting star $\tau$ Bo\"otis that extend the exceptional previous multi-year data set of its large-scale magnetic field. Our results confirm that the large-scale magnetic field ... More
Quantum Optical State Comparison AmplifierNov 22 2013It is a fundamental principle of quantum theory that an unknown state cannot be copied or, as a consequence, an unknown optical signal cannot be amplified deterministically and perfectly. Here we describe a protocol that provides nondeterministic quantum ... 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
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
Linear independence of translates implies linear independence of affine Parseval frames on LCA groupsNov 05 2014Aug 30 2016Motivated by Bownik and Speegle's result on linear independence of wavelet Parseval frames, we consider affine systems (analogous to wavelet systems) defined on a second countable, locally compact abelian group $G$, where the translations are replaced ... 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
Frictional quantum decoherenceJul 19 2007The dynamics associated with a measurement-based master equation for quantum Brownian motion are investigated. A scheme for obtaining time evolution from general initial conditions is derived. This is applied to analyze dissipation and decoherence in ... 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
Atomic RetrodictionJul 04 2001Measurement of a quantum system provides information concerning the state in which it was prepared. In this paper we show how the retrodictive formalism can be used to evaluate the probability associated with any one of a given set of preparation events. ... 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.
Carleson measure and balayageAug 07 2009The balayage of a Carleson measure lies of course in BMO. We show that the converse statement is false. We also make a two-sided estimate of the Carleson norm of a positive measure in terms of balayages.
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
Embeddings between operator-valued dyadic BMO spacesMay 06 2008We investigate a scale of dyadic operator-valued BMO spaces, corresponding to the different yet equivalent characterizations of dyadic BMO in the scalar case. In the language of operator spaces, we investigate different operator space structures on the ... More
Operator-valued dyadic BMO spacesMay 01 2008We consider BMO spaces of operator-valued functions, among them the space of operator-valued functions $B$ which define a bounded paraproduct on $L^2(H)$. We obtain several equivalent formulations of $\|\pi_B\|$ in terms of the norm of the "sweep" function ... More
Ermakov-Pinney and Emden-Fowler equations: new solutions from novel Bäcklund transformationsNov 12 2017The class of nonlinear ordinary differential equations $y^{\prime\prime}y = F(z,y^2)$, where F is a smooth function, is studied. Various nonlinear ordinary differential equations, whose applicative importance is well known, belong to such a class of nonlinear ... More
Magnetic fields in M dwarfs from the CARMENES surveyApr 29 2019M dwarfs are known to generate the strongest magnetic fields among main-sequence stars with convective envelopes, but the link between the magnetic fields and underlying dynamo mechanisms, rotation, and activity still lacks a consistent picture. In this ... More
Generation of $k$-jets on Toric VarietiesOct 15 1997In this notes we study $k$-jet ample line bundles $L$ on a non singular toric variety $X$, i.e. line bundles with global sections having arbitrarily prescribed $k$-jets at a finite number of points. We introduce the notion of an associated $k$-convex ... More
Stabilizing Transmission Intervals for Nonlinear Delayed Networked Control Systems [Extended Version]Apr 15 2016In this article, we consider a nonlinear process with delayed dynamics to be controlled over a communication network in the presence of disturbances and study robustness of the resulting closed-loop system with respect to network-induced phenomena such ... More
Predicting Branch Visits and Credit Card Up-selling using Temporal Banking DataJul 20 2016Sep 07 2016There is an abundance of temporal and non-temporal data in banking (and other industries), but such temporal activity data can not be used directly with classical machine learning models. In this work, we perform extensive feature extraction from the ... More
A singular perturbation problem for a quasilinear operator satisfying the natural growth condition of LiebermanDec 27 2007In this paper we study the following problem. For any $\ep>0$, take $u^{\ep}$ a solution of, $$ \L u^{\ep}:= {div}\Big(\di\frac {g(|\nabla \uep|)}{|\nabla \uep|}\nabla \uep\Big)=\beta_{\ep}(u^{\ep}),\quad u^{\ep}\geq 0. $$ A solution to $(P_{\ep})$ is ... More
Computing The Invariants of Intersection Algebras of Principal Monomial IdealsOct 02 2018We continue the study of intersection algebras $\mathcal B = \mathcal B_R(I, J)$ of two ideals $I, J$ in a commutative Noetherian ring $R$. In particular, we exploit the semigroup ring and toric structures in order to calculate various invariants of the ... More
Photonic Quantum Operations via the Quantum Carburettor EffectJan 16 2017The bosonic nature of light leads to counter-intuitive bunching effects. We describe an experimentally testable effect in which a single photon is induced through a highly reflecting beamsplitter by a large amplitude coherent state, with probability 1/e ... More
Grassmann Phase Space Methods for Fermions. II. Field TheoryApr 12 2016Apr 19 2016In both quantum optics and cold atom physics, the behaviour of bosonic photons and atoms is often treated using phase space methods, where mode annihilation and creation operators are represented by c-number phase space variables, with the density operator ... More
Semiclassical theory of matter-wave detectionJun 11 2003We derive a semiclassical theory for the detection of matter-waves. This theory draws on the theories of semiclassical optical detection and fluid mechanics. We observe that the intrinsically dispersive nature of matter-waves is important in deriving ... More
Bayes' theorem and quantum retrodictionJun 25 2001We derive on the basis of Bayes' theorem a simple but general expression for the retrodicted premeasurement state associated with the result of any measurement. The retrodictive density operator is the normalised probability operator measure element associated ... More
Retrodiction as a tool for micromaser field measurementsJul 16 2002We use retrodictive quantum theory to describe cavity field measurements by successive atomic detections in the micromaser. We calculate the state of the micromaser cavity field prior to detection of sequences of atoms in either the excited or ground ... More
On the mechanical properties of matter wavesJul 05 2004Electromagnetic waves and fluids have locally conserved mechanical properties associated with them and we may expect these to exist for matter waves. We present a semiclassical description of the continuity equations relating to these conserved properties ... More
Quantum retrodiction in open systemsAug 13 2002Quantum retrodiction involves finding the probabilities for various preparation events given a measurement event. This theory has been studied for some time but mainly as an interesting concept associated with time asymmetry in quantum mechanics. Recent ... More
A Bcool magnetic snapshot survey of solar-type starsNov 14 2013Stellar magnetic field measurements obtained from spectropolarimetry offer key data for activity and dynamo studies, and we present the results of a major high-resolution spectropolarimetric Bcool project magnetic snapshot survey of 170 solar-type stars ... 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
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
Torsion in kernels of induced maps on divisor class groupsFeb 26 2013We investigate torsion elements in the kernel of the map on divisor class groups of excellent local normal domains A and A/I, for an ideal I of finite projective dimension. The motivation for this work is a result of Griffith-Weston which applies when ... More
Local Quantum Thermometry using Unruh-De Witt detectorsSep 05 2016Mar 31 2017We propose an operational definition for the local temperature of a quantum field employing Unruh-DeWitt detectors, as used in the study of the Unruh and Hawking effects. With this definition, an inhomogeneous quantum system in equilibrium can have different ... More
Quantum probability rule: a generalisation of the theorems of Gleason and BuschAug 05 2013Apr 16 2014Busch's theorem deriving the standard quantum probability rule can be regarded as a more general form of Gleason's theorem. Here we show that a further generalisation is possible by reducing the number of quantum postulates used by Busch. We do not assume ... More
Grassmann Variables and the Jaynes-Cummings ModelMar 22 2012This paper shows that phase space methods using a positive P type distribution function involving both c-number variables (for the cavity mode) and Grassmann variables (for the two level atom) can be used to treat the Jaynes-Cummings model. Although it ... More
The CARMENES search for exoplanets around M dwarfs: Different roads to radii and masses of the target starsApr 05 2019We determine the radii and masses of 293 nearby, bright M dwarfs of the CARMENES survey. This is the first time that such a large and homogeneous high-resolution (R>80 000) spectroscopic survey has been used to derive these fundamental stellar parameters. ... 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
Capture of Leptophilic Dark Matter in Neutron StarsApr 22 2019Dark matter particles will be captured in neutron stars if they undergo scattering interactions with nucleons or leptons. These collisions transfer the dark matter kinetic energy to the star, resulting in appreciable heating that is potentially observable ... More
Generalization of the normal-exponential model: exploration of a more accurate parametrisation for the signal distribution on Illumina BeadArraysDec 18 2011Sep 17 2012Motivation: Illumina BeadArray technology includes negative control features that allow a precise estimation of the background noise. As an alternative to the background subtraction proposed in BeadStudio which leads to an important loss of information ... 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
Solo or Ensemble? Choosing a CNN Architecture for Melanoma ClassificationApr 29 2019Convolutional neural networks (CNNs) deliver exceptional results for computer vision, including medical image analysis. With the growing number of available architectures, picking one over another is far from obvious. Existing art suggests that, when ... 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
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
Central Limit Theorem with Exchangeable Summands and Mixtures of Stable Laws as LimitsApr 19 2012The problem of convergence in law of normed sums of exchangeable random variables is examined. First, the problem is studied w.r.t. arrays of exchangeable random variables, and the special role played by mixtures of products of stable laws - as limits ... 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
On Laplace-Carleson embedding theoremsJan 04 2012Oct 10 2012This paper gives embedding theorems for a very general class of weighted Bergman spaces: the results include a number of classical Carleson embedding theorems as special cases. We also consider little Hankel operators on these Bergman spaces. Next, a ... More
Tangential interpolation in weighted vector-valued H^p spaces, with applicationsJun 06 2008In this paper, norm estimates are obtained for the problem of minimal-norm tangential interpolation by vector-valued analytic functions in weighted H^p spaces, expressed in terms of the Carleson constants of related scalar measures. Applications are given ... More
HBT Interferometry for Sonoluminescence BubbleDec 18 1996The two-photon correlation of the light pulse emitted from a sonoluminescence bubble is discussed. It is shown that several important information about the mechanism of light emission, such as the time-scale and the shape of the emission region could ... 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
The common ancestor process revisitedMay 25 2013Dec 06 2013We consider the Moran model in continuous time with two types, mutation, and selection. We concentrate on the ancestral line and its stationary type distribution. Building on work by Fearnhead (J. Appl. Prob. 39 (2002), 38-54) and Taylor (Electron. J. ... More
Dusty MgII Absorbers: Implications for the GRB/Quasar Incidence DiscrepancyApr 21 2009May 04 2009There is nearly a factor of four difference in the number density of intervening MgII absorbers as determined from gamma-ray burst (GRB) and quasar lines of sight. We use a Monte-Carlo simulation to test if a dust extinction bias can account for this ... More
A matrix weighted $T1$ theorem for matrix kernelled Calderon Zygmund operators - IJan 25 2014Mar 17 2017In this series of two papers, we will prove a natural matrix weighted $T1$ theorem for matrix kernelled CZOs. In the current paper, we will prove matrix weighted norm inequalities for matrix symbolled paraproducts via a general matrix weighted Carleson ... More
Implementing a Library for Probabilistic Programming using Non-strict Non-determinismMay 17 2019This paper presents PFLP, a library for probabilistic programming in the functional logic programming language Curry. It demonstrates how the concepts of a functional logic programming language support the implementation of a library for probabilistic ... 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.
A bound on the scrambling index of a primitive matrix using Boolean rankOct 11 2009The scrambling index of an $n\times n$ primitive matrix $A$ is the smallest positive integer $k$ such that $A^k(A^{t})^k=J$, where $A^t$ denotes the transpose of $A$ and $J$ denotes the $n\times n$ all ones matrix. For an $m\times n$ Boolean matrix $M$, ... More
Experimental Implementation of a Quantum Optical State Comparison AmplifierApr 16 2014Quantum optical amplification that beats the noise addition limit for deterministic amplifiers has been realized experimentally using several different nondeterministic protocols. These schemes either require single-photon sources, or operate by noise ... More
Retrodictive states and two-photon quantum imagingMar 17 2003We use retrodictive quantum theory to analyse two-photon quantum imaging systems. The formalism is particularly suitable for calculating conditional probability distributions.
Coherent absorption of N00N statesMar 14 2016Recent results in deeply subwavelength thickness films demonstrated coherent control and logical gate operations with both classical and single photon light sources. However, quantum processing and devices typically involve more than one photon and non-trivial ... More
$H^2$ regularity for the $p(x)-$Laplacian in two-dimensional convex domainsJul 15 2011Jul 20 2011In this paper we study the $H^2$ global regularity for solutions of the $p(x)-$Laplacian in two dimensional convex domains with Dirichlet boundary conditions. Here $p:\Omega \to [p_1,\infty)$ with $p\in Lip(\bar{\Omega})$ and $p_1>1$.
Local rigidity for Yamabe-type problems in warped productsJan 31 2015Aug 04 2015Our aim in this paper is to study local rigidity for metrics defined on a compact manifold $M$ with boundary satisfying constant scalar curvature on $M$ and constant mean curvature on $\partial M$. We present some geometrical hypotheses ensuring local ... More
Rigidity and bifurcation results for CMC hypersurfaces in warped product spacesJul 28 2014In this paper, we deduce some rigidity results in warped product spaces under normal variations of CMC hypersurfaces. In particular, we prove the existence of one-parameter families locally rigid on the spatial fiber of Anti-de Sitter Schwarzschild spacetime ... More
A Free boundary problem for the $p(x)$- LaplacianFeb 18 2009We consider the optimization problem of minimizing $\int_{\Omega}|\nabla u|^{p(x)}+ \lambda \chi_{\{u>0\}} dx$ in the class of functions $W^{1,p(\cdot)}(\Omega)$ with $u-\phi_0\in W_0^{1,p(\cdot)}(\Omega)$, for a given $\phi_0\geq 0$ and bounded. $W^{1,p(\cdot)}(\Omega)$ ... More
Matrix weighted norm inequalities for commutators and paraproducts with matrix symbolsJul 14 2015Mar 17 2017Let $B$ be a locally integrable matrix function, $W$ a matrix A${}_p$ weight with $1 < p < \infty$, and $T$ be any of the Riesz transforms. We will characterize the boundedness of the commutator $[T, B]$ on $L^p(W)$ in terms of the membership of $B$ in ... 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
A matrix weighted bilinear Carleson Lemma and Maximal FunctionNov 14 2018We prove a bilinear Carleson embedding theorem with matrix weight and scalar measure. In the scalar case, this becomes exactly the well known weighted bilinear Carleson embedding theorem. Although only allowing scalar Carleson measures, it is to date ... More
From GWAS to transcriptomics in prospective cancer design - new statistical challengesMar 14 2013Background. With the increasing interest in post-GWAS research which represents a transition from genome-wide association discovery to analysis of functional mechanisms, attention has been lately focused on the potential of including various biological ... 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
Measurement master equationFeb 17 2006We derive a master equation describing the evolution of a quantum system subjected to a sequence of observations. These measurements occur randomly at a given rate and can be of a very general form. As an example, we analyse the effects of these measurements ... More
Maximum Confidence Quantum MeasurementsApr 05 2006We consider the problem of discriminating between states of a specified set with maximum confidence. For a set of linearly independent states unambiguous discrimination is possible if we allow for the possibility of an inconclusive result. For linearly ... More
Sidechains and interoperabilityMar 10 2019Mar 22 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
The Complexity of Learning Acyclic Conditional Preference NetworksJan 11 2018Feb 05 2019Learning of user preferences, as represented by, for example, Conditional Preference Networks (CP-nets), has become a core issue in AI research. Recent studies investigate learning of CP-nets from randomly chosen examples or from membership and equivalence ... More
Gliese 49: Activity evolution and detection of a super-EarthMar 12 2019Mar 25 2019Small planets around low-mass stars often show orbital periods in a range that corresponds to the temperate zones of their host stars which are therefore of prime interest for planet searches. Surface phenomena such as spots and faculae create periodic ... 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
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
The Type II-Plateau Supernova 2017eaw in NGC 6946 and Its Red Supergiant ProgenitorMar 09 2019Apr 18 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
Laboratory rotational ground state transitions of NH$_3$D$^+$ and CF$^+$Jul 08 2016Aims. This paper reports accurate laboratory frequencies of the rotational ground state transitions of two astronomically relevant molecular ions, NH3D+ and CF+. Methods. Spectra in the millimeter-wave band were recorded by the method of rotational state-selective ... 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
Lebesgue's Density Theorem and definable selectors for idealsNov 15 2018May 21 2019We 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. In contrast to these results, ... More
Multiple imputation using dimension reduction techniques for high-dimensional dataMay 13 2019Missing data present challenges in data analysis. Naive analyses such as complete-case and available-case analysis may introduce bias and loss of efficiency, and produce unreliable results. Multiple imputation (MI) is one of the most widely used methods ... More
Universal quantum control of two-electron spin quantum bits using dynamic nuclear polarizationSep 27 2010One fundamental requirement for quantum computation is to perform universal manipulations of quantum bits at rates much faster than the qubit's rate of decoherence. Recently, fast gate operations have been demonstrated in logical spin qubits composed ... More
Enhancing the Coherence of a Spin Qubit by Operating it as a Feedback Loop That Controls its Nuclear Spin BathMar 21 2010Nov 27 2010In many realizations of electron spin qubits the dominant source of decoherence is the fluctuating nuclear spin bath of the host material. The slowness of this bath lends itself to a promising mitigation strategy where the nuclear spin bath is prepared ... 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
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
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
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