Results for "Magnus V. Persson"

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Shrinking targets in parametrised familiesMar 03 2016May 03 2016We consider certain parametrised families of piecewise expanding maps on the interval, and estimate and sometimes calculate the Hausdorff dimension of the set of parameters for which the orbit of a fixed point has a certain shrinking target property. ... More
Tracing the atomic nitrogen abundance in star-forming regions with ammonia deuterationFeb 23 2018Partitioning of elemental nitrogen in star-forming regions is not well constrained. Most nitrogen is expected to be partitioned among atomic nitrogen, molecular nitrogen (N2), and icy N-bearing molecules, such as ammonia (NH3) and N2. Atomic nitrogen ... More
Linking interstellar and cometary O$_2$: a deep search for $^{16}$O$^{18}$O in the solar-type protostar IRAS 16293--2422May 31 2018Recent measurements carried out at comet 67P/C-G with the ${\it Rosetta}$ probe revealed that molecular oxygen, O$_2$, is the fourth most abundant molecule in comets. Models show that O$_2$ is likely of primordial nature, coming from the interstellar ... More
astroquery: An Astronomical Web-Querying Package in PythonJan 14 2019astroquery is a collection of tools for requesting data from databases hosted on remote servers with interfaces exposed on the internet, including those with web pages but without formal application program interfaces (APIs). These tools are built on ... More
A Triple Protostar System Formed via Fragmentation of a Gravitationally Unstable DiskOct 26 2016Binary and multiple star systems are a frequent outcome of the star formation process, and as a result, almost half of all sun-like stars have at least one companion star. Theoretical studies indicate that there are two main pathways that can operate ... More
Warm water deuterium fractionation in IRAS 16293-2422 - The high-resolution ALMA and SMA viewNov 28 2012Measuring the water deuterium fractionation in the inner warm regions of low-mass protostars has so far been hampered by poor angular resolution obtainable with single-dish ground- and space-based telescopes. Observations of water isotopologues using ... More
Subarcsecond resolution observations of warm water towards three deeply embedded low-mass protostarsMar 22 2012Water is present during all stages of star formation: as ice in the cold outer parts of protostellar envelopes and dense inner regions of circumstellar disks, and as gas in the envelopes close to the protostars, in the upper layers of circumstellar disks ... More
The role of grain boundary scattering in reducing the thermal conductivity of polycrystalline XNiSn (X = Hf, Zr, Ti) half-Heusler alloysJul 13 2017Oct 11 2017Thermoelectric application of half-Heusler compounds suffers from their fairly high thermal conductivities. Insight into how effective various scattering mechanisms are in reducing the thermal conductivity of fabricated XNiSn compounds (X = Hf, Zr, Ti, ... More
On the Dirac and Pauli operators with several Aharonov-Bohm solenoidsApr 04 2006We study the self-adjoint Pauli operators that can be realized as the square of a self-adjoint Dirac operator and correspond to a magnetic field consisting of a finite number of Aharonov-Bohm solenoids and a regular part, and prove an Aharonov-Casher ... More
Eigenvalue asymptotics of the even-dimensional exterior Landau-Neumann HamiltonianJun 27 2008We study the Schroedinger operator with a constant magnetic field in the exterior of a compact domain in $\mathbb{R}^{2d}$, $d\geq 1$. The spectrum of this operator consists of clusters of eigenvalues around the Landau levels. We give asymptotic formulas ... More
Inter-ribbon tunneling in graphene: an atomistic Bardeen approachDec 19 2015Mar 10 2016A weakly coupled system of two crossed graphene nanoribbons exhibits direct tunneling due to the overlap of the wavefunctions of both ribbons. We apply the Bardeen transfer Hamiltonian formalism, using atomistic band structure calculations to account ... More
Detection of glycolaldehyde towards the solar-type protostar NGC1333 IRAS2AFeb 03 2015Glycolaldehyde is a key molecule in the formation of biologically relevant molecules such as ribose. We report its detection with the Plateau de Bure interferometer towards the Class 0 young stellar object NGC1333 IRAS2A, which is only the second solar-type ... More
An optimal transport approach to Monge-Ampère equations on compact Hessian manifoldsJul 11 2016In this paper we consider Monge-Amp\`ere equations on compact Hessian manifolds, or equivalently Monge-Amp\`ere equations on certain unbounded convex domains $\Omega\subseteq \mathbb{R}^n$, with a periodicity constraint given by the action of an affine ... More
Hausdorff dimension of random limsup setsDec 21 2016Jan 04 2017We prove bounds for the almost sure value of the Hausdorff dimension of the limsup set of a sequence of balls in $\mathbf{R}^d$ whose centres are independent, identically distributed random variables. The formulas obtained involve the rate of decrease ... More
Safe Open-Loop Strategies for Handling Intermittent Communications in Multi-Robot SystemsFeb 11 2017In multi-robot systems where a central decision maker is specifying the movement of each individual robot, a communication failure can severely impair the performance of the system. This paper develops a motion strategy that allows robots to safely handle ... More
On the magnitude function of domains in Euclidean spaceJun 21 2017Nov 21 2017We study Leinster's notion of magnitude for a compact metric space. For a smooth, compact domain $X\subset \mathbb{R}^{2m-1}$, we find geometric significance in the function $\mathcal{M}_X(R) = \mathrm{mag}(R\cdot X)$. The function $\mathcal{M}_X$ extends ... More
Parameterized Algorithms for Zero Extension and Metric Labelling ProblemsFeb 16 2018We consider the problems ZERO EXTENSION and METRIC LABELLING under the paradigm of parameterized complexity. These are natural, well-studied problems with important applications, but have previously not received much attention from parameterized complexity. ... More
Clusters of eigenvalues for the magnetic Laplacian with Robin conditionJun 04 2014We study the Schr\"{o}dinger operator with a constant magnetic field in the exterior of a compact domain in euclidean space. Functions in the domain of the operator are subject to a boundary condition of the third type (a magnetic Robin condition). In ... More
Commutator estimates on contact manifolds and applicationsDec 30 2013Jun 28 2015This article studies sharp norm estimates for the commutator of pseudo-differential operators with multiplication operators on closed Heisenberg manifolds. In particular, we obtain a Calderon commutator estimate: If $D$ is a first-order operator in the ... More
Nonclassical spectral asymptotics and Dixmier traces: From circles to contact manifoldsJun 01 2016We consider the spectral behavior and noncommutative geometry of commutators $[P,f]$, where $P$ is an operator of order $0$ with geometric origin and $f$ a multiplication operator by a function. When $f$ is H\"{o}lder continuous, the spectral asymptotics ... More
Persistification of Robotic TasksMar 14 2019In this paper we propose a control framework that enables robots to execute tasks persistently, i. e., over time horizons much longer than robots' battery life, which is achieved by ensuring that the energy stored in the batteries of the robots is never ... More
Which NP-Hard SAT and CSP Problems Admit Exponentially Improved Algorithms?Jan 29 2018We study the complexity of SAT($\Gamma$) problems for potentially infinite languages $\Gamma$ closed under variable negation (sign-symmetric languages). Via an algebraic connection, this reduces to the study of restricted partial polymorphisms of $\Gamma$ ... More
Convergence of an Adaptive Approximation Scheme for the Wiener ProcessFeb 02 2010The problem of approximating/tracking the value of a Wiener process is considered. The discretization points are placed at times when the value of the process differs from the approximation by some amount, here denoted by eta. It is found that the limiting ... More
Effects of different Form-factors in Meson-Photon-Photon Transitions and the Muon Anomalous Magnetic MomentJun 13 2001The exact form of the form-factor associated with a meson-photon-photon vertex is not known. Different suggestions exist, based on constraints from QCD and on recent experiments. Four different form-factors are studied in this article. We calculate decay ... More
Full Restoration of Visual Encrypted Color ImagesNov 18 2011While strictly black and white images have been the basis for visual cryptography, there has been a lack of an easily implemented format for colour images. This paper establishes a simple, yet secure way of implementing visual cryptography with colour, ... More
A note on approximation of plurisubharmonic functionsSep 15 2016We extend a recent result of Avelin, Hed, and Persson about approximation of functions $u$ that are plurisubharmonic on a domain $\Omega$ and continuous on $\bar\Omega$, with functions that are plurisubharmonic on (shrinking) neighborhoods of $\bar\Omega$. ... More
Simplified a priori Estimate for the Time Periodic Burgers' EquationMay 03 2012We present here a version of the existence and uniqueness result of time periodic solutions to the viscous Burgers equation with irregular forcing terms (with Sobolev regularity -1 in space). The key result here is an a priori estimate which is simpler ... More
Newton maps as matings of cubic polynomialsAug 18 2014In this paper we prove existence of matings between a large class of renormalizable cubic polynomials with one fixed critical point and another cubic polynomial having two fixed critical points. The resulting mating is a Newton map. Our result is the ... More
A Sparse and High-Order Accurate Line-Based Discontinuous Galerkin Method for Unstructured MeshesApr 06 2012Oct 05 2012We present a new line-based discontinuous Galerkin (DG) discretization scheme for first- and second-order systems of partial differential equations. The scheme is based on fully unstructured meshes of quadrilateral or hexahedral elements, and it is closely ... More
Reticulation-visible networksAug 21 2015Jun 25 2017Let $X$ be a finite set, $\mathcal N$ be a reticulation-visible network on $X$, and $\mathcal T$ be a rooted binary phylogenetic tree. We show that there is a polynomial-time algorithm for deciding whether or not $\mathcal N$ displays $\mathcal T$. Furthermore, ... More
Enabling accurate first-principle calculations of electronic properties with a corrected k.p schemeJul 05 2016Mar 22 2017A computationally inexpensive k.p-based interpolation scheme is developed that can extend the eigenvalues and momentum matrix elements of a sparsely sampled k-point grid into a densely sampled one. Dense sampling, often required to accurately describe ... More
A generalized finite element method for linear thermoelasticityApr 01 2016We propose and analyze a generalized finite element method designed for linear quasistatic thermoelastic systems with spatial multiscale coefficients. The method is based on the local orthogonal decomposition technique introduced by M{\aa}lqvist and Peterseim ... More
A non-existence result for the Ginzburg-Landau equationsJul 11 2009Sep 30 2009We consider the stationary Ginzburg-Landau equations in $\R^d$, $d=2,3$. We exhibit a class of applied magnetic fields (including constant fields) such that the Ginzburg-Landau equations do not admit finite energy solutions.
Rotationally-supported disks around Class I sources in Taurus: disk formation constraintsDec 19 2013(Abridged) Disks are observed around pre-main sequence stars, but how and when they form is still heavily debated. While disks around young stellar objects have been identified through thermal dust emission, spatially and spectrally resolved molecular ... More
Wireless Capacity and Admission Control in Cognitive RadioNov 22 2011Jan 19 2012We give algorithms with constant-factor performance guarantees for several capacity and throughput problems in the SINR model. The algorithms are all based on a novel LP formulation for capacity problems. First, we give a new constant-factor approximation ... More
Relative geometric assembly and mapping cones, Part I: The geometric model and applicationsJul 07 2015Aug 15 2018Inspired by an analytic construction of Chang, Weinberger and Yu, we define an assembly map in relative geometric $K$-homology. The properties of the geometric assembly map are studied using a variety of index theoretic tools (e.g., the localized index ... More
Hochschild cohomology of some quantum complete intersectionsMar 17 2017We compute the Hochschild cohomology ring of the algebras $A= k\langle X, Y\rangle/ (X^a, XY-qYX, Y^a)$ over a field $k$ where $a\geq 2$ and where $q\in k$ is a primitive $a$-th root of unity. We find the the dimension of $\mathrm{HH}^n(A)$ and show that ... More
Towards Tight Bounds for Local BroadcastingJul 08 2012Oct 16 2012We consider the local broadcasting problem in the SINR model, which is a basic primitive for gathering initial information among $n$ wireless nodes. Assuming that nodes can measure received power, we achieve an essentially optimal constant approximate ... More
Wireless Connectivity and CapacityOct 05 2011Given $n$ wireless transceivers located in a plane, a fundamental problem in wireless communications is to construct a strongly connected digraph on them such that the constituent links can be scheduled in fewest possible time slots, assuming the SINR ... More
The Spectrum of Volterra-type integration operators on generalized Fock spacesSep 04 2015We describe the spectrum of certain integration operators acting on general- ized Fock spaces.
Lack of diamagnetism and the Little-Parks effectMay 19 2014When a superconducting sample is submitted to a sufficiently strong external magnetic field, the superconductivity of the material is lost. In this paper we prove that this effect does not, in general, take place at a unique value of the external magnetic ... More
On Colorings of Squares of Outerplanar GraphsJun 11 2007We study vertex colorings of the square $G^2$ of an outerplanar graph $G$. We find the optimal bound of the inductiveness, chromatic number and the clique number of $G^2$ as a function of the maximum degree $\Delta$ of $G$ for all $\Delta\in \nats$. As ... More
Rapid mixing of subset Glauber dynamics on graphs of bounded tree-widthFeb 17 2011Motivated by the `subgraphs world' view of the ferromagnetic Ising model, we develop a general approach to studying mixing times of Glauber dynamics based on subset expansion expressions for a class of graph polynomials. With a canonical paths argument, ... More
A sharp boundedness result concerning some maximal operators of Vilenkin-Fejér meansOct 21 2014In this paper we derive the maximal subspace of positive numbers, for which the restricted maximal operator of Fej\'er means in this subspace is bounded from the Hardy space $H_{p}$ to the space $L_{p}$ for all $0<p\leq 1/2.$ Moreover, we prove that the ... More
On the semi-classical analysis of the groundstate energy of the Dirichlet Pauli operator in non-simply connected domainsFeb 08 2017Feb 13 2017We consider the Dirichlet Pauli operator in bounded connected domains in the plane, with a semi-classical parameter. We show, in particular, that the ground state energy of this Pauli operator will be exponentially small as the semi-classical parameter ... More
Analysis and entropy stability of the line-based discontinuous Galerkin methodSep 26 2018Apr 29 2019We develop a discretely entropy-stable line-based discontinuous Galerkin method for hyperbolic conservation laws based on a flux differencing technique. By using standard entropy-stable and entropy-conservative numerical flux functions, this method guarantees ... More
The Compact Discontinuous Galerkin (CDG) Method for Elliptic ProblemsFeb 13 2007Sep 15 2008We present a compact discontinuous Galerkin (CDG) method for an elliptic model problem. The problem is first cast as a system of first order equations by introducing the gradient of the primal unknown, or flux, as an additional variable. A standard discontinuous ... More
On the asymptotics of the scenery flowSep 06 2013Various notions of "zooming in" on measures exist in the literature and the scenery flow is one of them. It is of interest to describe the joint asymptotics of the scenery flows generated by a measure and the measure transported by a local diffeomorphism. ... More
Imaging the water snowline in a protostellar envelope with H$^{13}$CO$^+$Jan 08 2018Snowlines are key ingredients for planet formation. Providing observational constraints on the locations of the major snowlines is therefore crucial for fully connecting planet compositions to their formation mechanism. Unfortunately, the most important ... More
ALMA observations of the kinematics and chemistry of disc formationMay 06 2014May 12 2014Context: The R CrA cloud hosts a handful of Class 0/I low-mass young stellar objects. The chemistry and physics at scales $>500$ AU in this cloud are dominated by the irradiation from the nearby Herbig Be star R CrA. The luminous large-scale emission ... More
A Frostman type lemma for sets with large intersections, and an application to Diophantine approximationFeb 05 2013Sep 11 2017We consider classes $\mathscr{G}^s ([0,1])$ of subsets of $[0,1]$, originally introduced by Falconer, that are closed under countable intersections, and such that every set in the class has Hausdorff dimension at least $s$. We provide a Frostman type ... More
Passivity-Based Decentralized Control of Multi-Robot Systems With Delays Using Control Barrier FunctionsApr 09 2019In this paper, we present a solution to the problem of coordinating multiple robots across a communication channel that experiences delays. The proposed approach leverages control barrier functions in order to ensure that the multi-robot system remains ... More
Voluntary Retreat for Decentralized Interference Reduction in Robot SwarmsDec 05 2018Mar 10 2019In densely-packed robot swarms operating in confined regions, spatial interference -- which manifests itself as a competition for physical space -- forces robots to spend more time navigating around each other rather than performing the primary task. ... More
Monte Carlo Methods for the Game KingdominoJul 12 2018Jul 15 2018Kingdomino is introduced as an interesting game for studying game playing: the game is multiplayer (4 independent players per game); it has a limited game depth (13 moves per player); and it has limited but not insignificant interaction among players. ... More
The bordism group of unbounded KK-cyclesMar 25 2015Jul 27 2016We consider Hilsum's notion of bordism as an equivalence relation on unbounded $KK$-cycles and study the equivalence classes. Upon fixing two $C^*$-algebras, and a $*$-subalgebra dense in the first $C^*$-algebra, a $\mathbb{Z}/2\mathbb{Z}$-graded abelian ... More
Resistance of a MoleculeAug 08 2002In recent years, several experimental groups have reported measurements of the current-voltage (I-V) characteristics of individual or small numbers of molecules. Our purpose in this chapter is to provide an intuitive explanation for the observed I-V characteristics ... More
Incremental dimension reduction of tensors with random indexMar 18 2011We present an incremental, scalable and efficient dimension reduction technique for tensors that is based on sparse random linear coding. Data is stored in a compactified representation with fixed size, which makes memory requirements low and predictable. ... More
Ab-initio elastic tensor of cubic Ti$_{0.5}$Al$_{0.5}$N alloy: the dependence of the elastic constants on the size and shape of the supercell modelNov 02 2011In this study we discuss the performance of approximate SQS supercell models in describing the cubic elastic properties of B1 (rocksalt) Ti$_{0.5}$Al$_{0.5}$N alloy by using a symmetry based projection technique. We show on the example of Ti$_{0.5}$Al$_{0.5}$N ... More
Modeling the absorption spectrum of the permanganate ion in vacuum and in aqueous solutionJan 20 2017Feb 22 2017The absorption spectrum of the MnO$_{4}$$^{-}$ ion has been a test-bed for quantum-chemical methods over the last decades. Its correct description requires highly-correlated multiconfigurational methods, which are incompatible with the inclusion of finite-temperature ... More
Hierarchical Distribution Matching for Probabilistically Shaped Coded ModulationSep 05 2018Dec 26 2018The implementation difficulties of combining distribution matching (DM) and dematching (invDM) for probabilistic shaping (PS) with soft-decision forward error correction (FEC) coding can be relaxed by reverse concatenation, for which the FEC coding and ... More
Performance Metrics for Systems with Soft-Decision FEC and Probabilistic ShapingApr 28 2017Oct 02 2017High-throughput optical communication systems utilize binary soft-decision forward error correction (SD-FEC) with bit interleaving over the bit channels. The generalized mutual information (GMI) is an achievable information rate (AIR) in such systems ... More
Finite element convergence for the time-dependent Joule heating problem with mixed boundary conditionsJan 30 2018We prove strong convergence for a large class of finite element methods for the time-dependent Joule heating problem in three spatial dimensions with mixed boundary conditions on Lipschitz domains. We consider conforming subspaces for the spatial discretization ... More
Multiscale differential Riccati equations for linear quadratic regulator problemsJun 14 2017Jun 18 2018We consider approximations to the solutions of differential Riccati equations in the context of linear quadratic regulator problems, where the state equation is governed by a multiscale operator. Similarly to elliptic and parabolic problems, standard ... More
Some new $\left(H_{p},L_{p}\right)$ type inequalities of maximal operators of Vilenkin-Nörlund means with non-decreasing coefficientsApr 21 2015In this paper we prove and discuss some new $\left(H_{p},L_{p}\right)$ type inequalities of maximal operators of Vilenkin-N\"orlund means with non-decreasing coefficients. We also apply these inequalities to prove strong convergence theorems of such Vilenkin-N\"orlund ... More
Multi-robot motion planning via optimal transport theoryApr 04 2019In this work we establish a simple yet effective strategy, based on optimal transport theory, for enabling a group of robots to accomplish complex tasks, such as shape formation and assembly. We demonstrate the feasibility of this approach and rigorously ... More
Permissive Barrier Certificates for Safe Stabilization Using Sum-of-squaresFeb 24 2018Motivated by the need to simultaneously guarantee safety and stability of safety-critical dynamical systems, we construct permissive barrier certificates in this paper that explicitly maximize the region where the system can be stabilized without violating ... More
Calculation of Discrepancy Measures and ApplicationsMay 07 2014In this book chapter we survey known approaches and algorithms to compute discrepancy measures of point sets. After providing an introduction which puts the calculation of discrepancy measures in a more general context, we focus on the geometric discrepancy ... More
Asynchronous Multi-Agent Primal-Dual OptimizationJun 07 2016We present a framework for asynchronously solving nonlinear optimization problems over networks of agents which are augmented by the presence of a centralized cloud computer. This framework uses a Tikhonov-regularized primal-dual approach in which the ... More
Empirical Big Data Research: A Systematic Literature MappingSep 10 2015Background: Big Data is a relatively new field of research and technology, and literature reports a wide variety of concepts labeled with Big Data. The maturity of a research field can be measured in the number of publications containing empirical results. ... More
Stringent limits on the magnetic field strength in the disc of TW Hya: ALMA observations of CN polarisationApr 02 2019Despite their importance in the star formation process, measurements of magnetic field strength in proto-planetary discs remain rare. While linear polarisation of dust and molecular lines can give insight into the magnetic field structure, only observations ... More
The distribution of superconductivity near a magnetic barrierSep 28 2017We consider the Ginzburg-Landau functional, defined on a two-dimensional simply connected domain with smooth boundary, in the situation when the applied magnetic field is piecewise constant with a jump discontinuity along a smooth curve. In the regime ... More
Logarithmic means \dots]{On the Nörlund logarithmic means with respect to Vilenkin system in the martingale Hardy space $H_{1}$Feb 14 2018In this paper we prove and discuss a new divergence result of N\"orlund logarithmic means with respect to Vilenkin system in Hardy space $H_1. $
Physics of suction cupsMay 22 2019We have developed a theory for the contact between suction cups and randomly rough surfaces. The theory predicts the dependency of the pull-off time (lifetime) on the pull-off force, and is tested with measurements performed on suction cups made from ... More
Shrinking targets and eventually always hitting points for interval mapsMar 16 2019We study shrinking target problems and the set $\mathcal{E}_{\text{ah}}$ of eventually always hitting points. These are the points whose first $n$ iterates will never have empty intersection with the $n$-th target for sufficiently large $n$. We derive ... More
Quasiperiodic localized oscillating solutions in the discrete nonlinear Schrödinger equation with alternating on-site potentialDec 29 2003Aug 30 2004We present what we believe to be the first known example of an exact quasiperiodic localized stable solution with spatially symmetric large-amplitude oscillations in a non-integrable Hamiltonian lattice model. The model is a one-dimensional discrete nonlinear ... More
3D sub-nanoscale imaging of unit cell doubling due to octahedral tilting and cation modulation in strained perovskite thin filmsOct 17 2018Oct 24 2018Determining the 3-dimensional crystallography of a material with sub-nanometre resolution is essential to understanding strain effects in epitaxial thin films. A new scanning transmission electron microscopy imaging technique is demonstrated that visualises ... More
Atom-atom correlations in colliding Bose-Einstein condensatesJul 31 2008Mar 10 2009We analyze atom-atom correlations in the s-wave scattering halo of two colliding condensates. By developing a simple perturbative approach, we obtain explicit analytic results for the collinear (CL) and back-to-back (BB) correlations corresponding to ... More
Atom-atom correlations and relative number squeezing in dissociation of spatially inhomogeneous molecular condensatesJun 10 2008Jul 18 2008We study atom-atom correlations and relative number squeezing in the dissociation of a Bose-Einstein condensate (BEC) of molecular dimers made of either bosonic or fermionic atom pairs. Our treatment addresses the role of the spatial inhomogeneity of ... More
Gap and out-gap breathers in a binary modulated discrete nonlinear Schrödinger modelDec 17 2003We consider a modulated discrete nonlinear Schr\"odinger (DNLS) model with alternating on-site potential, having a linear spectrum with two branches separated by a 'forbidden' gap. Nonlinear localized time-periodic solutions with frequencies in the gap ... More
Role of spatial inhomogeneity in dissociation of trapped molecular condensatesMay 04 2009Jul 31 2010We theoretically analyze dissociation of a harmonically trapped Bose-Einstein condensate of molecular dimers and examine how the spatial inhomogeneity of the molecular condensate affects the conversion dynamics and the atom-atom pair correlations in the ... More
The ALMA-PILS survey: The sulphur connection between protostars and comets: IRAS 16293-2422 B and 67P/Churyumov-GerasimenkoFeb 08 2018Feb 21 2018The evolutionary past of our Solar System can be pieced together by comparing analogous low-mass protostars with remnants of our Protosolar Nebula - comets. Sulphur-bearing molecules may be unique tracers of the joint evolution of the volatile and refractory ... More
A recent accretion burst in the low-mass protostar IRAS 15398-3359: ALMA imaging of its related chemistryDec 03 2013Low-mass protostars have been suggested to show highly variable accretion rates through-out their evolution. Such changes in accretion, and related heating of their ambient envelopes, may trigger significant chemical variations on different spatial scales ... More
The ALMA-PILS survey: The sulphur connection between protostars and comets: IRAS 16293-2422 B and 67P/Churyumov-GerasimenkoFeb 08 2018The evolutionary past of our Solar System can be pieced together by comparing analogous low-mass protostars with remnants of our Protosolar Nebula - comets. Sulphur-bearing molecules may be unique tracers of the joint evolution of the volatile and refractory ... More
High D$_2$O/HDO ratio in the inner regions of the low-mass protostar NGC1333 IRAS2AJul 25 2014Aug 16 2014Water plays a crucial role both in the interstellar medium and on Earth. To constrain its formation mechanisms and its evolution through the star formation process, the determination of the water deuterium fractionation ratios is particularly suitable. ... More
Path-contractions, edge deletions and connectivity preservationApr 21 2017We study several problems related to graph modification problems under connectivity constraints from the perspective of parameterized complexity: {\sc (Weighted) Biconnectivity Deletion}, where we are tasked with deleting~$k$ edges while preserving biconnectivity ... More
Herdable Systems Over Signed, Directed GraphsApr 11 2018This paper considers the notion of herdability, a set-based reachability condition, which asks whether the state of a system can be controlled to be element-wise larger than a non-negative threshold. The basic theory of herdable systems is presented, ... More
Monitoring Targeted Hate in Online EnvironmentsMar 13 2018Hateful comments, swearwords and sometimes even death threats are becoming a reality for many people today in online environments. This is especially true for journalists, politicians, artists, and other public figures. This paper describes how hate directed ... More
UmUTracker: A versatile MATLAB program for automated particle tracking of 2D light microscopy or 3D digital holography dataJan 27 2017Apr 21 2017We present a versatile and fast MATLAB program (UmUTracker) that automatically detects and tracks particles by analyzing video sequences acquired by either light microscopy or digital in-line holographic microscopy. Our program detects the 2D lateral ... More
On the Hausdorff Dimension of Bernoulli ConvolutionsJan 22 2018We give an expression for the Garsia entropy of Bernoulli convolutions in terms of products of matrices. This gives an explicit rate of convergence of the Garsia entropy and shows that one can calculate the Hausdorff dimension of the Bernoulli convolution ... More
Optimizing Constellations for Single-Subcarrier Intensity-Modulated Optical SystemsJun 14 2011Feb 07 2012We optimize modulation formats for the additive white Gaussian noise channel with nonnegative input, also known as the intensity-modulated direct-detection channel, with and without confining them to a lattice structure. Our optimization criteria are ... More
Clique cover and graph separation: New incompressibility resultsNov 02 2011The field of kernelization studies polynomial-time preprocessing routines for hard problems in the framework of parameterized complexity. Although a framework for proving kernelization lower bounds has been discovered in 2008 and successfully applied ... More
Wireless Network Stability in the SINR ModelOct 16 2012We study the stability of wireless networks under stochastic arrival processes of packets, and design efficient, distributed algorithms that achieve stability in the SINR (Signal to Interference and Noise Ratio) interference model. Specifically, we make ... More
A Fully Distributed Algorithm for Throughput Performance in Wireless NetworksMar 18 2012We study link scheduling in wireless networks under stochastic arrival processes of packets, and give an algorithm that achieves stability in the physical (SINR) interference model. The efficiency of such an algorithm is the fraction of the maximum feasible ... More
Cotorsion torsion triples and the representation theory of filtered hierarchical clusteringApr 15 2019We give a full classification of representation types of the subcategories of representations of an $m \times n$ rectangular grid with monomorphisms (dually, epimorphisms) in one or both directions, which appear naturally in the context of clustering ... More
Quasiparticle Corrections to the Electronic Properties of Anion Vacancies at GaAs(110) and InP(110)Nov 27 2006We propose a new method for calculating optical defect levels and thermodynamic charge-transition levels of point defects in semiconductors, which includes quasiparticle corrections to the Kohn-Sham eigenvalues of density-functional theory. Its applicability ... More
Hierarchies of Inefficient KernelizabilityOct 05 2011The framework of Bodlaender et al. (ICALP 2008) and Fortnow and Santhanam (STOC 2008) allows us to exclude the existence of polynomial kernels for a range of problems under reasonable complexity-theoretical assumptions. However, there are also some issues ... More
Classification of Big Data with Application to Imaging GeneticsMay 16 2016Big data applications, such as medical imaging and genetics, typically generate datasets that consist of few observations n on many more variables p, a scenario that we denote as p>>n. Traditional data processing methods are often insufficient for extracting ... More
Recovering tree-child networks from shortest inter-taxa distance informationNov 24 2017Phylogenetic networks are a type of leaf-labelled, acyclic, directed graph used by biologists to represent the evolutionary history of species whose past includes reticulation events. A phylogenetic network is tree-child if each non-leaf vertex is the ... More
Rubber friction on (apparently) smooth lubricated surfacesOct 18 2007We study rubber sliding friction on hard lubricated surfaces. We show that even if the hard surface appears smooth to the naked eye, it may exhibit short wavelength roughness, which may give the dominant contribution to rubber friction. That is, the observed ... More
Spectral properties of superconductors with ferromagnetically ordered magnetic impuritiesSep 15 2015We present a comprehensive theoretical study of thermodynamic properties of superconductors with a dilute concentration of magnetic impurities, with focus on how the properties of the superconducting host change if the magnetic moments of the impurities ... More