Results for "Manuel Meyer"

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Magnetic screening properties of superconductor-ferromagnet bilayersMar 12 2009Sep 28 2009We study theoretically the magnetic screening properties of thin, diffusive superconductor/ferromagnet bilayers subject to a perpendicular magnetic field. We find that the effective penetration depth characterizing the magnetic response oscillates with ... More
Searches for Axionlike Particles Using Gamma-Ray ObservationsNov 23 2016Axionlike particles (ALPs) are a common prediction of theories beyond the Standard Model of particle physics that could explain the entirety of the cold dark matter. These particles could be detected through their mixing with photons in external electromagnetic ... More
Weak localization in transition metal dichalcogenide monolayers and their heterostructures with grapheneAug 17 2018Apr 14 2019We calculate the interference correction to the conductivity of doped transition metal dichalcogenide (TMDC) monolayers. Because of the interplay between valley structure and intrinsic spin-orbit coupling (SOC), these materials exhibit a rich weak localization ... More
Class Schema Evolution for Persistent Object-Oriented Software: Model, Empirical Study, and Automated SupportMar 03 2011Jun 21 2012With the wide support for object serialization in object-oriented programming languages, persistent objects have become common place and most large object-oriented software systems rely on extensive amounts of persistent data. Such systems also evolve ... More
Magnetic resonance in a singlet-triplet Josephson junctionSep 01 2015We study a singlet-triplet Josephson junction between a conventional s-wave superconductor and an unconventional p$_{\rm x}$-wave superconductor. The Andreev spectrum of the junction yields a spontaneous magnetization in equilibrium. This allows manipulating ... More
Online Top-k-Position Monitoring of Distributed Data StreamsOct 29 2014Consider n nodes connected to a single coordinator. Each node receives an individual online data stream of numbers and, at any point in time, the coordinator has to know the k nodes currently observing the largest values, for a given k between 1 and n. ... More
Modelling gamma-ray-axion-like particle oscillations in turbulent magnetic fields: relevance for observations with Cherenkov telescopesDec 08 2014Axion-like particles (ALPs) are a common prediction of certain theories beyond the Standard Model and couple to photons in the presence of external magnetic fields. As a consequence, photon-ALP conversions could lead to an enhancement of the flux of extragalactic ... More
Signatures of odd-frequency correlations in the Josephson current of superconductor/ferromagnet hybrid junctionsApr 16 2015Contacting a bilayer ferromagnet with a singlet even-frequency superconductor allows for the realization of an effective triplet odd-frequency superconductor. In this work, we investigate the Josephson effect between superconductors with different symmetries ... More
Probing the peak of the star formation rate density with the extragalactic background lightMar 01 2012Jul 19 2012The extragalactic background light (EBL), i.e., the diffuse meta-galactic photon field in the ultraviolet to infrared, is dominated by the emission from stars in galaxies. It is, therefore, intimately connected with the integrated star formation rate ... More
Efficiently Generating Geometric Inhomogeneous and Hyperbolic Random GraphsMay 16 2019Hyperbolic random graphs (HRG) and geometric inhomogeneous random graphs (GIRG) are two similar generative network models that were designed to resemble complex real world networks. In particular, they have a power-law degree distribution with controllable ... More
Pair-production opacity at high and very-high gamma-ray energiesSep 16 2013The propagation of high energy (HE, $E_\gamma>100$ MeV) and very high-energy gamma-rays (VHE, $E_\gamma>100$ GeV) in the extra-galactic photon field leads to pair-production and consequently energy- and distance-dependent attenuation of the primary intensity. ... More
Indications for a pair-production anomaly from the propagation of VHE gamma-raysJan 23 2012Jan 30 2012In the recent years, the number of detected very high energy (VHE: E > 100 GeV) gamma-ray sources has increased rapidly. The sources have been observed at redshifts up to z = 0.536 without strong indications for the presence of absorption features in ... More
Impact of oscillations of photons into axion-like particles on the very-high energy gamma-ray spectrum of the blazar PKS1424+240Oct 08 2013Very high energy (VHE) gamma-rays undergo pair production with low energy photons of background radiation fields. This leads to an attenuation of the primary gamma-ray flux of extragalactic sources in the interaction with the extragalactic background ... More
Fragile Complexity of Comparison-Based AlgorithmsJan 09 2019We initiate a study of algorithms with a focus on the computational complexity of individual elements, and introduce the fragile complexity of comparison-based algorithms as the maximal number of comparisons any individual element takes part in. We give ... More
The Search for the Laws of Automatic Random TestingNov 14 2012Can one estimate the number of remaining faults in a software system? A credible estimation technique would be immensely useful to project managers as well as customers. It would also be of theoretical interest, as a general law of software engineering. ... More
Episodic excursions of low-mass protostars on the Hertzsprung-Russell diagramDec 28 2018Following our recent work devoted to the effect of accretion on the pre-main-sequence evolution of low-mass stars, we perform a detailed analysis of episodic excursions of low-mass protostars in the Hertzsprung-Russell (H-R) diagram triggered by strong ... More
Non-trivial Chern numbers in three-terminal Josephson junctionsMay 06 2017Recently it has been predicted that the Andreev bound state spectrum of 4-terminal Josephson junctions may possess zero-energy Weyl singularities. Using one superconducting phase as a control parameter, these singularities are associated with topological ... More
Majorana-Weyl crossings in topological multi-terminal junctionsOct 23 2018We analyze the Andreev spectrum in a four-terminal Josephson junction between one-dimensional topological superconductors in class D. We find that a topologically protected crossing in the space of three superconducting phase differences can occur between ... More
Quasiclassical theory of disordered Rashba superconductorsFeb 16 2015Jul 30 2015We derive the quasiclassical equations that describe two-dimensional superconductors with a large Rashba spin-orbit coupling and in the presence of impurities. These equations account for the helical phase induced by an in-plane magnetic field, with a ... More
First lower limits on the photon-axion-like particle coupling from very high energy gamma-ray observationFeb 05 2013Aug 26 2013The intrinsic flux of very high energy (VHE, Energy > 100 GeV) gamma-rays from extragalactic sources is attenuated due to pair production in the interaction with photons of the extragalactic background light (EBL). Depending on the distance of the source, ... More
Enhancement of the upper critical field in disordered transition metal dichalcogenide monolayersMay 04 2017Jun 16 2017We calculate the effect of impurities on the superconducting phase diagram of transition metal dichalcogenide monolayers in the presence of an in-plane magnetic field. Due to strong intrinsic spin-orbit coupling, the upper critical field greatly surpasses ... More
Non-equilibrium spin transport in Zeeman-split superconductorsDec 22 2014Mar 08 2015We investigate theoretically the non-local conductance through a superconducting wire in tunnel contact with normal and ferromagnetic leads. In the presence of an in-plane magnetic field, the superconducting density of states is spin-split, and the current ... More
Andreev current induced by ferromagnetic resonanceApr 06 2012We study charge transport through a metallic dot coupled to a superconducting and a ferromagnetic lead with a precessing magnetization due to ferromagnetic resonance. Using the quasiclassical theory, we find that the magnetization precession induces a ... More
Studying cosmological $γ$-ray propagation with the Cherenkov Telescope ArraySep 13 2017Sep 26 2017The measurement of $\gamma$-rays originating from active galactic nuclei offers the unique opportunity to study the propagation of very-high-energy photons over cosmological distances. Most prominently, $\gamma$-rays interact with the extragalactic background ... More
Sensitivity of the Cherenkov Telescope Array to the Detection of Intergalactic Magnetic FieldsMar 10 2016Aug 22 2016Very high energy (VHE; energy $E \gtrsim 100\,$GeV) $\gamma$-rays originating from extragalactic sources undergo pair production with low-energy photons of background radiation fields. These pairs can inverse-Compton-scatter background photons, initiating ... More
On detecting oscillations of gamma rays into axion-like particles in turbulent and coherent magnetic fieldsJun 23 2014Sep 04 2014Background radiation fields pervade the Universe, and above a certain energy any $\gamma$-ray flux emitted by an extragalactic source should be attenuated due to $e^+e^-$ pair production. The opacity could be alleviated if photons oscillated into hypothetical ... More
Weak localization in transition metal dichalcogenide monolayers and their heterostructures with grapheneAug 17 2018We calculate the interference correction to the conductivity of doped transition metal dichalcogenide monolayers (TMDC). Because of the interplay between valley structure and intrinsic spin-orbit coupling (SOC), these materials exhibit a rich weak localization ... More
Superharmonic long-range triplet current in a diffusive Josephson junctionMar 05 2013We study the Josephson current through a long ferromagnetic bilayer in the diffusive regime. For non-collinear magnetizations, we find that the current-phase relation is dominated by its second harmonic, which corresponds to the long-range coherent propagation ... More
Topological Josephson $φ_0$-junctionsMar 06 2015Jul 24 2015We study the effect of a magnetic field on the current-phase relation of a topological Josephson junction formed by connecting two superconductors through the helical edge states of a quantum spin-Hall insulator. We predict that the Zeeman effect along ... More
Diffuse axion-like particle searchesDec 05 2017We propose a new method to search for axion-like particles (ALPs) based on the gamma-rays produced concomitant with high-energy astrophysical neutrinos. The existence of high-energy neutrinos implies production of gamma-rays in the same sources. Photons ... More
Revisiting the Indication for a low opacity Universe for very high energy gamma-raysNov 27 2012Jan 10 2013Very high energy (VHE, energy >~ 100 GeV) {\gamma}-rays undergo pair production with photons of the extragalactic background light (EBL). Thus, the intrinsic {\gamma}-ray flux of cosmological sources is attenuated and the Universe should be opaque to ... More
Constraints on Axions and Axionlike Particles from Fermi Large Area Telescope Observations of Neutron StarsJan 30 2016We present constraints on the nature of axions and axionlike particles (ALPs) by analyzing gamma--ray data from neutron stars using the Fermi Large Area Telescope. In addition to axions solving the strong CP problem of particle physics, axions and ALPs ... More
The VHE Gamma-Ray View of the FSRQ PKS~1510-089Mar 20 2019The flat spectrum radio quasar PKS 1510-089 is a monitored target in many wavelength bands due to its high variability. It was detected as a very-high-energy (VHE) $\gamma$-ray emitter with H.E.S.S. in 2009, and has since been a regular target of VHE ... More
Theory of ProgramsJul 02 2015Dec 07 2015A general theory of programs, programming and programming languages built up from a few concepts of elementary set theory. Derives, as theorems, properties treated as axioms by classic approaches to programming. Covers sequential and concurrent computation. ... More
Towards a Calculus of Object ProgramsJul 11 2011Jul 17 2011Verifying properties of object-oriented software requires a method for handling references in a simple and intuitive way, closely related to how O-O programmers reason about their programs. The method presented here, a Calculus of Object Programs, combines ... More
Modularity experiments on $S_4$-symmetric double octicsOct 08 2018We will invest quite some computer power to find double octic threefolds that are connected to weight four modular forms.
Quantizing Two-Dimensional Dilaton Gravity with Fermions: The Vienna WayDec 28 2006I review recent work on nonperturbative path integral quantization of two-dimensional dilaton gravity coupled to Dirac fermions, employing the "Vienna school" approach.
Classical and Quantum Dilaton Gravity in Two Dimensions with FermionsJul 17 2006In this thesis the first order formulation of generalized dilaton gravities in two dimensions coupled to a Dirac fermion is considered. After a Hamiltonian analysis of the gauge symmetries and constraints of the theory and fixing Eddington-Finkelstein ... More
Vibrational band structure of nanoscale phononic crystalsNov 02 2015Nov 24 2017The vibrational properties of two-dimensional phononic crystals are studied with large-scale molecular dynamics simulations and finite element method calculation. The vibrational band structure derived from the molecular dynamics simulations shows the ... More
Cosmic Neutrinos and Other Light RelicsMay 18 2016Cosmological measurements of the radiation density in the early universe can be used as a sensitive probe of physics beyond the standard model. Observations of primordial light element abundances have long been used to place non-trivial constraints on ... More
High Precision Astrometry with Adaptive Optics aided ImagingMay 27 2010More than 450 exoplanets are known and this number increases nearly every day. Only a few constraints on their orbital parameters and physical characteristics can be determined, as most exoplanets are detected indirectly. Measuring the astrometric signal ... More
Extreme lattices and vexillar designsDec 14 2008We define a notion of vexillar design for the flag variety in the spirit of the spherical designs introduced by Delsarte, Goethals and Seidel. For a finite subgroup of the orthogonal group, we explain how conditions on the group have the orbits of any ... More
Generalized fixed point algebras and square-integrable group actionsNov 13 2000We analzye Rieffel's construction of generalized fixed point algebras in the setting of group actions on Hilbert modules. Let G be a locally compact group acting on a C*-algebra B. We construct a Hilbert module F over the reduced crossed product of G ... More
The Bivariate Normal CopulaDec 15 2009We collect well known and less known facts about the bivariate normal distribution and translate them into copula language. In addition, we prove a very general formula for the bivariate normal copula, we compute Gini's gamma, and we provide improved ... More
Representations of *-algebras by unbounded operators: C*-hulls, local-global principle, and inductionJul 15 2016Sep 29 2016We define a C*-hull for a *-algebra, given a notion of integrability for its representations on Hilbert modules. We establish a local-global principle which, in many cases, characterises integrable representations on Hilbert modules through the integrable ... More
Representations of *-algebras by unbounded operators: C*-hulls, local-global principle, and inductionJul 15 2016Jul 27 2017We define a C*-hull for a *-algebra, given a notion of integrability for its representations on Hilbert modules. We establish a local-global principle which, in many cases, characterises integrable representations on Hilbert modules through the integrable ... More
Selling train tickets by SMSJul 06 2011Selling train tickets has evolved in the last ten years from queuing in the railway station, to buying tickets on the internet and printing them. Both alternatives are still viable options, though they are time consuming or need printing devices. Nowadays ... More
A Popperian Falsification of Artificial Intelligence - Lighthill DefendedApr 23 2017Apr 18 2018The area of computation called artificial intelligence (AI) is falsified by describing a previous 1972 falsification of AI by British applied mathematician James Lighthill. It is explained how Lighthill's arguments continue to apply to current AI. It ... More
A spectral interpretation for the zeros of the Riemann zeta functionDec 14 2004Aug 27 2013Based on work of Alain Connes, I have constructed a spectral interpretation for zeros of L-functions. Here we specialise this construction to the Riemann zeta function. We construct an operator on a nuclear Frechet space whose spectrum is the set of non-trivial ... More
A more general method to classify up to equivariant KK-equivalence II: Computing obstruction classesSep 23 2018We describe Universal Coefficient Theorems for the equivariant Kasparov theory for C*-algebras with an action of the group of integers or over a unique path space, using KK-valued invariants. We compare the resulting classification up to equivariant KK-equivalence ... More
Searches for New Phenomena at the Tevatron and at HERAOct 02 2006Recent results on searches for new physics at Run II of the Tevatron and highlights from HERA are reported. The searches cover many different final states and a wide range of models. All analyses have at this point led to negative results, but some interesting ... More
A Valuation Theoretic Approach to Essential DimensionFeb 24 2012In this essay we explore the notion of essential dimension using the theory of valuations of fields. Given a field extension K/k and a valuation on K that is trivial on k, we prove that the rank of the valuation cannot exceed the transcendence degree ... More
New Charm(onium) Results from CDFSep 07 2003After many upgrades to the CDF detector and to the accelerator complex, Run II began in April 2001. The new detector has improved capabilities for charm physics, and first results from the analysis of early Tevatron Run II data are reported here.
Homological algebra in bivariant K-theory and other triangulated categories. IIJan 09 2008Dec 12 2008We use homological ideals in triangulated categories to get a sufficient criterion for a pair of subcategories in a triangulated category to be complementary. We apply this criterion to construct the Baum-Connes assembly map for locally compact groups ... More
A more general method to classify up to equivariant KK-equivalence II: Computing obstruction classesSep 23 2018Apr 27 2019We describe Universal Coefficient Theorems for the equivariant Kasparov theory for C*-algebras with an action of the group of integers or over a unique path space, using KK-valued invariants. We compare the resulting classification up to equivariant KK-equivalence ... More
Unmating of rational maps, sufficient criteria and examplesOct 31 2011Douady and Hubbard introduced the operation of mating of polynomials. This identifies two filled Julia sets and the dynamics on them via external rays. In many cases one obtains a rational map. Here the opposite question is tackled. Namely we ask when ... More
Expanding Thurston maps as quotientsOct 11 2009Oct 22 2012A Thurston map is a branched covering map $f\colon S^2\to S^2$ that is postcritically finite. Mating of polynomials, introduced by Douady and Hubbard, is a method to geometrically combine the Julia sets of two polynomials (and their dynamics) to form ... More
Invariant Peano curves of expanding Thurston mapsJul 09 2009Apr 09 2013We consider Thurston maps, i.e., branched covering maps $f\colon S^2\to S^2$ that are postcritically finite. In addition, we assume that $f$ is expanding in a suitable sense. It is shown that each sufficiently high iterate $F=f^n$ of $f$ is semi-conjugate ... More
Fourteen Years of Software Engineering at ETH ZurichDec 14 2017Dec 16 2017A Chair of Software Engineering existed at ETH Zurich, the Swiss Federal Insti-tute of Technology, from 1 October 2001 to 31 January 2016, under my leader-ship. Our work, summarized here, covered a wide range of theoretical and practi-cal topics, with ... More
Misbehavior in Mobile Application MarketsJul 06 2011Mobile application markets facilitate the distribution of applications and thus help developers advertise their work and customers find useful applications. In addition, the operators of mobile application markets can control the quality and the content ... More
Breaking GSM with rainbow TablesJul 06 2011Since 1998 the GSM security has been academically broken but no real attack has ever been done until in 2008 when two engineers of Pico Computing (FPGA manufacture) revealed that they could break the GSM encryption in 30 seconds with 200'000$ hardware ... More
Measuring Resonance Parameters of Heavy Higgs Bosons at TESLAAug 13 2003This study investigates the potential of the TESLA Linear Collider for measuring resonance parameters of Higgs bosons beyond the mass range studied so far. The analysis is based on the reconstruction of events from the Higgsstrahlung process e+e- -> HZ. ... More
Comparison of KE-Theory and KK-TheoryMar 13 2015Jun 01 2015We show that the character from the bivariant K-theory KE^G introduced by Dumitrascu to E^G factors through Kasparov's KK^G for any locally compact group G. Hence KE^G contains KK^G as a direct summand.
Non-equilibrium Josephson effect through helical edge statesAug 18 2011We study Josephson junctions between superconductors connected through the helical edge states of a two-dimensional topological insulator in the presence of a magnetic barrier. As the equilibrium Andreev bound states of the junction are 4Pi-periodic in ... More
Online Top-k-Position Monitoring of Distributed Data StreamsOct 29 2014Oct 27 2016Consider n nodes connected to a single coordinator. Each node receives an individual online data stream of numbers and, at any point in time, the coordinator has to know the k nodes currently observing the largest values, for a given k between 1 and n. ... More
I/O-Efficient Generation of Massive Graphs Following the LFR BenchmarkApr 29 2016Jun 14 2017LFR is a popular benchmark graph generator used to evaluate community detection algorithms. We present EM-LFR, the first external memory algorithm able to generate massive complex networks following the LFR benchmark. Its most expensive component is the ... More
How many quasiparticles can be in a superconductor?Mar 14 2016Experimentally and mysteriously, the concentration of quasiparticles in a gapped superconductor at low temperatures always by far exceeds its equilibrium value. We study the dynamics of localized quasiparticles in superconductors with a spatially fluctuating ... More
Characterizing the Gamma-Ray Variability of the Brightest Flat Spectrum Radio Quasars Observed with the Fermi LATFeb 06 2019May 08 2019Almost 10 yr of $\gamma$-ray observations with the Fermi Large Area Telescope (LAT) have revealed extreme $\gamma$-ray outbursts from flat spectrum radio quasars (FSRQs), temporarily making these objects the brightest $\gamma$-ray emitters in the sky. ... More
Characterizing the gamma-ray variability of the brightest flat spectrum radio quasars observed with the Fermi LATFeb 06 2019Almost 10 years of $\gamma$-ray observations with the Fermi Large Area Telescope (LAT) have revealed extreme $\gamma$-ray outbursts from flat spectrum radio quasars (FSRQs), temporarily making these objects the brightest $\gamma$-ray emitters in sky. ... More
Anomalous Josephson effect in semiconducting nanowires as a signature of the topologically nontrivial phaseDec 09 2015May 07 2016We study Josephson junctions made of semiconducting nanowires with Rashba spin-orbit coupling, where superconducting correlations are induced by the proximity effect. In the presence of a suitably directed magnetic field, the system displays the anomalous ... More
Limits on the extragalactic background light in the Fermi eraFeb 13 2012Very high energy (VHE, energy $E \gtrsim 100$\,GeV) \gamma-rays from cosmological sources are attenuated due to the interaction with photons of the extragalactic background light (EBL) in the ultraviolet to infrared wavelength band. The EBL, thus, leaves ... More
On Competitive Algorithms for Approximations of Top-k-Position Monitoring of Distributed StreamsJan 18 2016Oct 27 2016Consider the continuous distributed monitoring model in which $n$ distributed nodes, receiving individual data streams, are connected to a designated server. The server is asked to continuously monitor a function defined over the values observed across ... More
Density of states in gapped superconductors with pairing-potential impuritiesOct 30 2015We study the density of states in disordered s-wave superconductors with a small gap anisotropy. Disorder comes in the form of common nonmagnetic scatterers and pairing-potential impurities, which interact with electrons via an electric potential and ... More
Nonlocal spin correlations mediated by a superconductorApr 02 2013Nonlocal charge correlations induced in two normal metals contacted separately to a supercon- ductor have been studied intensively in the past few years. Here we investigate nonlocal correlations induced by the transfer of pure spin currents through a ... More
I/O-efficient Generation of Massive Graphs Following the LFR BenchmarkApr 29 2016Sep 02 2016LFR is a popular benchmark graph generator used to evaluate community detection algorithms. We present EM-LFR, the first external memory algorithm able to generate massive complex networks following the LFR benchmark. Its most expensive component is the ... More
On Competitive Algorithms for Approximations of Top-k-Position Monitoring of Distributed StreamsJan 18 2016Jan 21 2016Consider the continuous distributed monitoring model in which $n$ distributed nodes, receiving individual data streams, are connected to a designated server. The server is asked to continuously monitor a function defined over the values observed across ... More
The Top--Down Interpretation of Ultra--High Energy Cosmic RaysOct 29 2003The origin of Ultra--High Energy ($E \gsim 10^{20}$ eV) Cosmic Rays (UHECR) remains mysterious. I discuss ``top--down'' models, where UHECR originate from the decay of very massive, long--lived particles. I summarize the calculation of the spectrum of ... More
Deriving Specifications of Dependable Systems: toward a MethodSep 20 2010This paper proposes a method for deriving formal specifications of systems. To accomplish this task we pass through a non trivial number of steps, concepts and tools where the first one, the most important, is the concept of method itself, since we realized ... More
A Supersymmetric Explanation of the Excess of Higgs-Like Events at LEPFeb 08 2005May 25 2005Searches for the Standard Model Higgs boson by the four LEP experiments found excess events in two mass ranges: a 2.3 sigma excess around 98 GeV, and an 1.7 sigma excess around 115 GeV. The latter has been discussed widely in the literature, but the former ... More
Astroparticle Physics and CollidersOct 09 2002Oct 16 2002In this talk I discuss the interplay between collider physics and four topics of astro-particle physics: neutrino oscillations, electroweak baryogenesis, LSP Dark Matter, and ultra-high energy cosmic rays (UHECR). Some astrophysical scenarios can (only) ... More
Are the H1 and ZEUS "High Q^2 Anomalies" Compatible with Each Other?Mar 15 1997Mar 18 1997Both ZEUS and H1 have recently reported an excess of events at high $Q^2$ and high Bjorken--$x$. However, the $x$ distributions differ considerably; moreover, H1 sees more events with lower luminosity. Taken separately, the $x$ distributions and the number ... More
Hydrodynamics of the CFL superfluidNov 27 2008At asymptotic high density and low temperature quarks form Cooper pairs in a color-flavor locked (CFL) configuration. The diquark condensates break spontaneously the baryon symmetry, and this fact makes the CFL phase also superfluid. At low temperatures ... More
The Business of Selling Electronic DocumentsApr 21 2009The music industry has huge troubles adapting to the new technologies. As many pointed out, when copying music is essentially free and socially accepted it becomes increasingly tempting for users to infringe copyrights and copy music from one person to ... More
D-module generation in positive characteristic via Frobenius descentAug 09 2004In this short note I give an alternative proof of a generalization of the result in math.AC/0407464. Namely I show that for most regular rings R, the localization R[1/f] at an element f of R is generated as a module over the ring of differential operators ... More
Carnot heat engine efficiency with a paramagnetic gasMay 15 2019Considering ideal paramagnetic medium, in this paper we deduced an expression for the thermal efficiency of Carnot heat engine with a paramagnetic gas as working substance. We found that the efficiency depends on the limits of maximum and minimal temperature ... More
Special Holonomy on Special SpacesMar 06 2014We characterise simply-connected biquotients which potentially admit metrics of holonomy G_2. We prove that there are at most three real homotopy types of rationally elliptic such manifolds---all of them being formal. In the course of this examination ... More
$\mathcal O(n)$ working precision inverses for symmetric tridiagonal Toeplitz matrices with $\mathcal O(1)$ floating point calculationsNov 27 2016A well known numerical task is the inversion of large symmetric tridiagonal Toeplitz matrices, i.e., matrices whose entries equal $a$ on the diagonal and $b$ on the extra diagonals ($a, b\in \mathbb R$). The inverses of such matrices are dense and there ... More
A derivation of linearized Griffith energies from nonlinear modelsApr 07 2015Feb 09 2017We derive Griffith functionals in the framework of linearized elasticity from nonlinear and frame indifferent energies in brittle fracture via Gamma-convergence. The convergence is given in terms of rescaled displacement fields measuring the distance ... More
A Korn-type inequality in SBD for functions with small jump setsMay 04 2015Jul 21 2017We present a Korn-type inequality in a planar setting for special functions of bounded deformation. We prove that for each function in SBD$^2$ with sufficiently small jump set the distance of the function and its derivative from an infinitesimal rigid ... More
On characteristic classes of exotic manifold bundlesFeb 07 2018May 15 2019Given a closed simply connected manifold $M$ of dimension $2n\ge6$, we compare the ring of characteristic classes of smooth oriented bundles with fibre $M$ to the analogous ring resulting from replacing $M$ by the connected sum $M\sharp\Sigma$ with an ... More
Dynamical control of the constraints growth in free evolutions of Einstein's equationsApr 17 2003I present a new, simple method to dynamically control the growth of the discretized constraints during a free evolution of Einstein's equations. During an evolution, any given family of formulations is adjusted off the constraints surface in a way such ... More
Digital interferometric demodulation of Placido mires applied to corneal topographyApr 10 2012Apr 17 2012This paper presents a novel digital interferometric method to demodulate Placido fringe patterns. This is a synchronous method which uses a computer-stored conic-wavefront as demodulating reference. Here we focus on the experimental aspects to phase-demodulate ... More
Synchronous phase-demodulation of high spatial frequency, concentric-rings, Placido fringe patternsMar 08 2012Apr 17 2012Here a synchronous phase-demodulation method for high spatial frequency (HSF), concentric-rings Placido fringe pattern is proposed. The earliest use of this concentric-rings pattern was to gauge non-spherical irregularities of the human cornea by Portuguese ... More
On Methods for the Formal Specification of Fault Tolerant SystemsJul 08 2012This paper introduces different views for understanding problems and faults with the goal of defining a method for the formal specification of systems. The idea of Layered Fault Tolerant Specification (LFTS) is proposed to make the method extensible to ... More
A Supersymmetric Explanation of the Excess of Higgs--Like Events at the LHC and at LEPOct 24 2012Nov 29 2012The LHC collaborations have recently announced evidence for the production of a "Higgs--like" boson with mass near 125 GeV. The properties of the new particle are consistent (within still quite large uncertainties) with those of the Higgs boson predicted ... More
Supersymmetric Dark Matter 2004Oct 07 2004Recent cosmological data allow to determine the universal Dark Matter (DM) density to a precision of about 10%, if a simple, well-motivated ansatz for the spectrum of primordial density perturbations is correct. Not surprisingly, a thermal neutralino ... More
Recent Developments in Dark Matter PhysicsMar 07 1997After a short review of the arguments for the existence of Particle Dark Matter in the Universe, I list the most plausible candidates provided by particle physics, i.e. neutrinos, axions, and WIMPs. In each case I briefly describe how to estimate the ... More
An Introduction to SupersymmetryNov 25 1996A fairly elementary introduction to supersymmetric field theories in general and the minimal supersymmetric Standard Model (MSSM) in particular is given. Topics covered include the cancellation of quadratic divergencies, the construction of the supersymmetric ... More
Multiple Interactions in gamma gamma CollisionsJun 29 1995The cross--section for two--photon events with (at least) two independent partonic scatters is estimated, for LEP energies as well as a 500 GeV ``photon collider". This results in events with (at least) four central (mini--)jets. Such events might be ... More
Complexity Classification in Infinite-Domain Constraint SatisfactionJan 04 2012Sep 14 2016A constraint satisfaction problem (CSP) is a computational problem where the input consists of a finite set of variables and a finite set of constraints, and where the task is to decide whether there exists a satisfying assignment of values to the variables. ... More