Results for "Christian Klinke"

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Insights into the formation mechanism of two-dimensional lead halide nanostructuresApr 09 2018We present a colloidal synthesis strategy for lead halide nanosheets with a thickness of far below 100 nm. Due to the layered structure and the synthesis parameters the crystals of PbI2 are initially composed of many polytypes. We propose a mechanism ... More
Iron nanoparticle formation in a metal-organic matrix: from ripening to gluttonyMay 22 2008A simple method for the fabrication of metal nanoparticles is introduced. Heating metal-organic crystals in vacuum results in the formation of well defined metal particles embedded in a carbon matrix. The method is demonstrated for iron-phthalocyanine. ... More
Influence of the deposition conditions on the field emission properties of patterned nitrogenated carbon nanotube filmsMar 07 2013The electron field emission of patterned films of nitrogenated carbon nanotubes is shown to be decisively influenced by the deposition conditions. The growth was carried out by decomposing methane in a nitrogen/ammonia atmosphere using hot filament chemical ... More
New ways to synthesize lead sulfide nanosheets - substituted alkanes direct the growth of 2D nanostructuresJul 29 2016Two-dimensional colloidal nanosheets represent very attractive optoelectronic materials. They combine good lateral conductivity with solution-processability and geometry-tunable electronic properties. In case of PbS nanosheets, so far the synthesis was ... More
Molecular Doping of Electrochemically Prepared Triazine-based Carbon Nitride by 2,4,6-Triaminopyrimidine for Improved Photocatalytic PropertiesDec 14 2018The copolymerization of melamine with 2,4,6-triaminopyrimidine (TAP) in an electrochemical induced polymerization process leads to the formation of molecular doped poly (triazine imide) (PTI). The polymerization is based on the electrolysis of water and ... More
Quantum dot attachment and morphology control by carbon nanotubesJun 02 2008Novel applications in nanotechnology rely on the design of tailored nano-architectures. For this purpose, carbon nanotubes and nanoparticles are intensively investigated. In this work we study the influence of non-functionalized carbon nanotubes on the ... More
Field effect and photoconduction in Au25 Nanoclusters FilmsMay 02 2019Quantum confined Au nanoclusters exhibit molecule-like properties, including atomic precision and discrete energy levels. The electrical conductivity of Au nanocluster films can vary by several orders of magnitude, and is determined by the strength of ... More
Metal domain size dependent electrical transport in Pt-CdSe hybrid nanoparticle monolayersJul 08 2015Thin films prepared of semiconductor nanoparticles are promising for low-cost electronic applications such as transistors and solar cells. One hurdle for their breakthrough is their notoriously low conductivity. To address this, we precisely decorate ... More
Synthesis of InP nanoneedles and their use as Schottky devicesMar 02 2010Indium phosphide (InP) nanostructures have been synthesized by means of colloidal chemistry. Under appropriate conditions needle-shaped nanostructures composed of an In head and an InP tail with lengths up to several micrometers could be generated in ... More
Oxygen and light sensitive field-effect transistors based on ZnO nanoparticles attached to individual double-wall carbon nanotubesJan 03 2013The attachment of semiconducting nanoparticles to carbon nanotubes is one of the most challenging subjects in nanotechnology. Successful high coverage attachment and control over the charge transfer mechanism and photo-current generation opens a wide ... More
On the electric conductivity of highly ordered monolayers of monodisperse metal nanoparticlesJun 02 2009Monolayers of colloidally synthesized cobalt-platinum nanoparticles of different diameters characterized by TEM (transmission electron microscopy) were deposited on structured silicon oxide substrates and characterized by SEM (scanning electron microscopy), ... More
Sculpting of lead sulfide nanoparticles by means of acetic acid and dichloroethaneJul 10 2015Colloidal lead sulfide is a versatile material with great opportunities to tune the bandgap by electronic confinement and to adapt the optical and electrical properties to the target application. We present a new and simple synthetic route to control ... More
Attachment of colloidal nanoparticles to boron nitride nanotubesJan 25 2017There is a strong interest to attach nanoparticles non-covalently to one-dimensional systems like boron nitride nanotubes to form composites. The combination of those materials might be used for catalysis, in solar cells, or for water splitting. Additionally, ... More
Metal nanoparticle field-effect transistorFeb 08 2013Jul 26 2013We demonstrate that by means of a local top-gate current oscillations can be observed in extended, monolayered films assembled from monodisperse metal nanocrystals -- realizing transistor function. The oscillations in this metal-based system are due to ... More
Preparation of high-yield and ultra-pure Au25 nanoclusters: towards their implementation in real-world applicationsJan 25 2019Colloidal approaches allow for the synthesis of Au nanoclusters (NCs) with atomic precision and sizes ranging from a few to hundreds of atoms. In most of the cases, these processes involve a common strategy of thiol etching of initially polydisperse Au ... More
Solution-grown nanowire devices for sensitive and fast photo detectionJul 17 2015Highly sensitive and fast photodetector devices with CdSe quantum nanowires as active elements have been developed exploiting the advantages of electro- and wet-chemical routes. Bismuth nanoparticles electrochemically synthesized directly onto interdigitating ... More
Field-effect transistors made of individual colloidal PbS nanosheetsJul 29 2013Two-dimensional materials are considered for future quantum devices and are usually produced by extensive methods like molecular beam epitaxy. We report on the fabrication of field-effect transistors using individual ultra-thin lead sulfide nanostructures ... More
Morphology dependence of radial elasticity in multiwalled boron nitride nanotubesMay 09 2013We report on the measurement of the effective radial modulus of multiwalled Boron Nitride nanotubes with external radii in the range 3.7 to 36 nm and number of layers in between 5 and 48. These Boron Nitride nanotubes are radially much stiffer than previously ... More
Size, Shape, and Phase Control in Ultrathin CdSe NanosheetsJul 12 2017Ultrathin two-dimensional nanosheets raise a rapidly increasing interest due to their unique dimensionality-dependent properties. Most of the two-dimensional materials are obtained by exfoliation of layered bulk materials or are grown on substrates by ... More
Photovoltaic effect in individual asymmetrically contacted lead sulfide nanosheetsJul 16 2015Solution-processable, two-dimensional semiconductors are promising optoelectronic materials which could find application in low-cost solar cells. Lead sulfide nanocrystals raised attention since the effective band gap can be adapted over a wide range ... More
Enhanced field emission from multiwall carbon nanotube films by secondary growthApr 28 2006We have studied nickel, gold, and ferritin coatings on catalytically grown multiwall carbon nanotubes, as well as the generation of secondary nanotubes by resubmitting the decorated nanotubes to the chemical vapor deposition process. Nickel layers sputtered ... More
Coulomb blockade based field-effect transistors exploiting stripe-shaped channel geometries of self-assembled metal nanoparticlesJun 02 2016Metallic nanoparticles offer possibilities to build basic electric devices with new functionality and improved performance. Due to the small volume and the resulting low self-capacitance, each single nanoparticle exhibits a high charging energy. Thus, ... More
Copper sulfide nanosheets with shape-tunable plasmonic properties in the NIRDec 14 20182D copper sulfide nanocrystals are promising building blocks for plasmonic materials in the near-infrared (NIR) spectral region. We demonstrate precise shape and size control (hexagonal/triangle) of colloidal plasmonic copper sulfide (covellite) nano-prisms ... More
From dots to stripes to sheets - Shape control of lead sulfide nanostructuresMar 08 2016Controlling anisotropy in nanostructures is a challenging but rewarding task since confinement in one or more dimensions influences the physical and chemical properties of the items decisively. In particular, semiconducting nanostructures can be tailored ... More
Synthesis and thermoelectric characterization of Bi2Te3 nanoparticlesMar 02 2010We report a novel synthesis for near monodisperse, sub-10-nm Bi2Te3 nanoparticles. At first, a new reduction route to bismuth nanoparticles is described which are applied as starting materials in the formation of rhombohedral Bi2Te3 nanoparticles. After ... More
Sliding on a Nanotube: Interplay of Friction, Deformations and StructureJun 07 2013The frictional properties of individual carbon nanotubes (CNTs) are studied by sliding an atomic force microscopy tip across and along its principle axis. This direction-dependent frictional behavior is found to correlate strongly with the presence of ... More
High Performance n- and p-Type Field-Effect Transistors Based on Hybridly Surface-Passivated Colloidal PbS NanosheetsApr 09 2018Colloidally synthesized nanomaterials are among the promising candidates for future electronic devices due to their simplicity and the inexpensiveness of their production. Specifically, colloidal nanosheets are of great interest since they are conveniently ... More
Colloidal Lead Iodide NanoringsDec 14 2018Colloidal chemistry of nanomaterials experienced a tremendous development in the last decades. In the course of the journey 0D nanoparticles, 1D nanowires, and 2D nanosheets have been synthesized. They have in common to possess a simple topology. We present ... More
Supramolecular interaction of singlewall carbon nanotubes with a functional TTF-based mediator probed by field-effect transistor devicesJul 30 2013The supramolecular interaction between individual singlewall carbon nanotubes and a functional organic material based on tetrathiafulvalene (TTF) is investigated by means of electric transport measurements in field effect transistor configuration as well ... More
Tunable electrical transport through annealed monolayers of monodisperse cobalt-platinum nanoparticlesJan 05 2012We synthesized monodisperse cobalt-platinum nanoparticles Co(0.14-0.22)Pt(0.86-0.78) of 9 nm in diameter by colloidal chemistry methods and deposited them by the Langmuir-Blodgett technique as highly ordered monolayers onto substrates with e-beam defined ... More
3D characterization of CdSe nanoparticles attached to carbon nanotubesFeb 05 2009The crystallographic structure of CdSe nanoparticles attached to carbon nanotubes has been elucidated by means of high resolution transmission electron microscopy and high angle annular dark field scanning transmission electron microscopy tomography. ... More
Halogens in the synthesis of colloidal semiconductor nanocrystalsApr 09 2018In this review, we highlight the role of halogenated compounds in the colloidal synthesis of nanostructured semiconductors. Halogen-containing metallic salts used as precursors and halogenated hydrocarbons used as ligands allow stabilizing different shapes ... More
Virtually Bare Nanocrystal Surfaces - Significantly Enhanced Electrical Transport in CuInSe2 and CuIn(1-x)Ga(x)Se2 Thin Films upon Ligand Exchange with Thermally Degradable 1-Ethyl-5-thiotetrazoleJan 13 2015We present a facile and safe ligand exchange method for readily synthesized CuInSe2 (CIS) and CuIn(1-x)Ga(x)Se2 (CIGS) nanocrystals (NCs) from oleylamine to 1-ethyl-5-thiotetrazole which preserves the colloidal stability of the chalcopyrite structure. ... More
Colloidal Tin Sulfide Nanosheets: Formation Mechanism, Ligand-mediated Shape Tuning and Photo-detectionAug 13 2018Colloidal materials of tin(II) sulfide (SnS), as a layered semiconductor with a narrow band gap, are emerging as a potential alternative to the more toxic metal chalcogenides (PbS, PbSe, CdS, CdSe) for various applications such as electronic and optoelectronic ... More
CdS nanoparticles capped with 1-substituted 5-thiotetrazoles: Synthesis, characterization, and thermolysis of the surfactantApr 26 2013We propose a new type of surfactants, namely, tetrazole derivatives which can be controllably removed from the nanoparticle surface. Tetrazoles are a peculiar class of heterocyclic compounds. The presence of four nitrogen atoms in the tetrazole ring determines ... More
Tungsten oxide nanowire growth by chemically-induced strainMar 28 2006We have investigated the formation of tungsten oxide nanowires under different CVD conditions. We find that exposure of oxidized tungsten films to hydrogen and methane at 900C leads to the formation of a dense array of typically 10 nm diameter nanowires. ... More
Hindered rolling and friction anisotropy in supported carbon nanotubesJan 31 2012Carbon nanotubes (CNTs) are well known for their exceptional thermal, mechanical and electrical properties. For many CNT applications it is of the foremost importance to know their frictional properties. However, very little is known about the frictional ... More
Adhesion and size dependent friction anisotropy in boron nitride nanotubesApr 03 2013The frictional properties of individual multiwalled boron nitride nanotubes (BN-NTs) synthesized by chemical vapor deposition (CVD) and deposited on a silicon substrate are investigated using an atomic force microscope tip sliding along (longitudinal ... More
Towards colloidal spintronics through Rashba spin-orbit interaction in lead sulphide nanosheetsJun 16 2017Employing the spin degree of freedom of charge carriers offers the possibility to extend the functionality of conventional electronic devices, while colloidal chemistry can be used to synthesize inexpensive and tuneable nanomaterials. In order to benefit ... More
Growth and reductive transformation of a gold shell around pyramidal cadmium selenide nanocrystalsMar 16 2011We report the growth of an unstable shell-like gold structure around dihexagonal pyramidal CdSe nanocrystals in organic solution and the structural transformation to spherical domains by two means: i) electron beam irradiation (in situ) and (ii) addition ... More
Tailoring the diameter of decorated CN nanotubes by temperature variations using HF-CVDMar 10 2013Patterned films of decorated nitrogenated carbon (C-N) nanotubes were catalytically synthesised by hot filament chemical vapour deposition (HF-CVD) in a nitrogen-methane-ammonia environment. The systematic study of a transition between different kinds ... More
Carbon supported CdSe nanocrystalsMar 14 2009Insights to the mechanism of CdSe nanoparticle attachment to carbon nanotubes following the hot injection method are discussed. It was observed that the presence of water improves the nanotube coverage while Cl containing media are responsible for the ... More
Radial elasticity of multi-walled carbon nanotubesJan 26 2012We report an experimental and a theoretical study of the radial elasticity of multi-walled carbon nanotubes as a function of external radius. We use atomic force microscopy and apply small indentation amplitudes in order to stay in the linear elasticity ... More
In-plane anisotropic faceting of ultralarge and thin single-crystalline colloidal SnS nanosheetsMar 14 2019The colloidal synthesis of large thin two-dimensional (2D) nanosheets is fascinating but challenging, since the growth along the lateral and vertical dimensions need to be controlled independently. In-plane anisotropy in 2D nanosheets is attracting more ... More
Thermoelectric properties of lead chalcogenide core-shell nanostructuresJun 03 2012We present the full thermoelectric characterization of nanostructured bulk PbTe and PbTe-PbSe samples fabricated from colloidal core-shell nanoparticles followed by spark plasma sintering. An unusually large thermopower is found in both materials, and ... More
Preparation and electrical properties of cobalt-platinum nanoparticle monolayers deposited by the Langmuir-Blodgett techniqueJan 08 2009The Langmuir-Blodgett technique was utilized and optimized to produce closed monolayers of cobalt-platinum nanoparticles over vast areas. It is shown that sample preparation, "dipping angle", and subphase type have a strong impact on the quality of the ... More
ZT enhancement in solution-grown Sb(2-x)Bi(x)Te3 nanoplateletsMar 04 2011We report a solution-processed, ligand supported synthesis of 15-20 nm thick Sb(2-x)Bi(x)Te3 nanoplatelets. After complete ligand removal by a facile NH3-based etching procedure, the platelets are spark plasma sintered to a p-type nanostructured bulk ... More
Ultra-thin PbS sheets by two-dimensional oriented attachmentMar 15 2011Controlling anisotropy is a key concept to generate complex functionality in advanced materials. For this, oriented attachment of nanocrystal building blocks, a self assembly of particles into larger single crystalline objects, is one of the most promising ... More
Shape Evolution of CdSe Nanoparticles controlled by Halogen CompoundsJan 15 2015Halogen compounds are capable of playing an important role in the manipulation of nanoparticle shapes and properties. In a new approach, we examined the shape evolution of CdSe nanorods to hexagonal pyramids in a hot-injection synthesis under the influence ... More
Reversible attachment of platinum alloy nanoparticles to non-functionalized carbon nanotubesMar 02 2011The formation of monodisperse, tunable sized, alloyed nanoparticles of Ni, Co, or Fe with Pt and pure Pt nanoparticles attached to carbon nanotubes has been investigated. Following homogeneous nucleation, nanoparticles attach directly to non-functionalized ... More
On spatial and temporal multilevel dynamics and scaling effects in epileptic seizuresMar 30 2011Jul 29 2011Epileptic seizures are one of the most well-known dysfunctions of the nervous system. During a seizure, a highly synchronized behavior of neural activity is observed that can cause symptoms ranging from mild sensual malfunctions to the complete loss of ... More
Duck Traps: Two-dimensional Critical Manifolds in Planar SystemsAug 30 2018Nov 05 2018In this work we consider two-dimensional critical manifolds in planar fast-slow systems near fold and so-called canard (=`duck') points. These higher-dimension, and lower-codimension, situation is directly motivated by the case of hysteresis operators ... More
Friction force: from mechanics to thermodynamicsNov 17 2009Jul 01 2010We study some mechanical problems in which a friction force is acting on the system. Using the fundamental concepts of state, time evolution and energy conservation we explain how to extend Newtonian mechanics to thermodynamics. We arrive at the two laws ... More
On the relativistic KMS condition for the P(φ)_2 modelSep 29 2006The relativistic KMS condition introduced by Bros and Buchholz provides a link between quantum statistical mechanics and quantum field theory. We show that for the $P(\phi)_2$ model at positive temperature, the two point function for fields satisfies ... More
Spectral properties and chiral symmetry violations of (staggered) domain wall fermions in the Schwinger modelFeb 26 2016Jul 05 2016We follow up on a suggestion by Adams and construct explicit domain wall fermion operators with staggered kernels. We compare different domain wall formulations, namely the standard construction as well as Borici's modified and Chiu's optimal construction, ... More
Thermal Quantum Fields with Spatially Cut-off Interactions in 1+1 Space-time DimensionsJul 25 2003We construct interacting quantum fields in 1+1 space-time dimensions, representing charged or neutral scalar bosons at positive temperature and zero chemical potential. Our work is based on prior work by Klein and Landau and Hoegh-Krohn. Generalized path ... More
Staggered domain wall fermionsSep 16 2016We construct domain wall fermions with a staggered kernel and investigate their spectral and chiral properties numerically in the Schwinger model. In some relevant cases we see an improvement of chirality by more than an order of magnitude as compared ... More
Differential Characters and Geometric ChainsMar 26 2013Apr 09 2013We study Cheeger-Simons differential characters and provide geometric descriptions of the ring structure and of the fiber integration map. The uniqueness of differential cohomology (up to unique natural transformation) is proved by deriving an explicit ... More
Distances and large deviations in the spatial preferential attachment modelSep 26 2018Sep 27 2018We investigate two asymptotic properties of a spatial preferential-attachment model introduced by E. Jacob and P. M\"orters (2013). First, in a regime of strong linear reinforcement, we show that typical distances are at most of doubly-logarithmic order. ... More
A stabilizing iteration scheme for model predictive control based on relaxed barrier functionsMar 15 2016Apr 06 2016We propose and analyze a stabilizing iteration scheme for the algorithmic implementation of model predictive control for linear discrete-time systems. Polytopic input and state constraints are considered and handled by means of so-called relaxed logarithmic ... More
Thermal Quantum Fields without Cut-offs in 1+1 Space-time DimensionsMar 26 2004We construct interacting quantum fields in 1+1 dimensional Minkowski space, representing neutral scalar bosons at positive temperature. Our work is based on prior work by Klein and Landau and Hoegh-Krohn
Removable presymplectic singularities and the local splitting of Dirac structuresOct 20 2014Oct 27 2015We call a singularity of a presymplectic form $\omega$ removable in its graph if its graph extends to a smooth Dirac structure over the singularity. An example for this is the symplectic form of a magnetic monopole. A criterion for the removability of ... More
MPL - a program for computations with iterated integrals on moduli spaces of curves of genus zeroOct 14 2015We introduce the computer program MPL for computations with homotopy invariant iterated integrals on moduli spaces $\mathcal{M}_{0,n}$ of curves of genus 0 with $n$ ordered marked points. The program is an implementation of the algorithms presented in ... More
Predicting zero reductions in Gröbner basis computationsApr 01 2014Since Buchberger's initial algorithm for computing Gr\"obner bases in 1965 many attempts have been taken to detect zero reductions in advance. Buchberger's Product and Chain criteria may be known the most, especially in the installaton of Gebauer and ... More
Discrete Complex Structure on Surfel SurfacesFeb 12 2008This paper defines a theory of conformal parametrization of digital surfaces made of surfels equipped with a normal vector. The main idea is to locally project each surfel to the tangent plane, therefore deforming its aspect-ratio. It is a generalization ... More
No information or horizon paradoxes for Th. SmithsMay 04 2015'Th'e 'S'tatistical 'm'echanician 'i'n 'th'e 's'treet (our Th. Smiths) must be surprised upon hearing popular versions of some of today's most discussed paradoxes in astronomy and cosmology. In fact, rather standard reminders of the meaning of thermal ... More
Many-body theory of degenerate systems: A simple exampleDec 05 2003The hierarchy of Green functions for (quasi)degenerate systems, presented in cond-mat/0308058, is calculated in detail for the case of a system with closed shells plus a single electron in a two-fold degenerate level. The complete hierarchy is derived ... More
Renormalization of QED in an external fieldFeb 08 2002The Schwinger equations of QED are rewritten in three different ways as integral equations involving functional derivatives, which are called weak field, strong field, and SCF quantum electrodynamics. The perturbative solutions of these equations are ... More
Quantum field theory of degenerate systemsJul 22 2003To set up a self-consistent quantum field theory of degenerate systems, the unperturbed state should be described by a density matrix instead of a pure state. This increases the combinatorial complexity of the many-body equations. Hopf algebraic techniques ... More
Vacuum Polarisation Tensors in Constant Electromagnetic Fields: Part IIFeb 25 2000In the second part of this series we apply the ``string-inspired'' technique to the calculation of one-loop amplitudes involving both vectors and axialvectors, as well as a general constant electromagnetic background field. The vector-axialvector two-point ... More
Cataclysmic Variables in Globular ClustersDec 05 2011Feb 10 2012Every massive globular cluster (GC) is expected to harbour a significant population of cataclysmic variables (CVs). In this review, I first explain why GC CVs matter astrophysically, how many and what types are theoretically predicted to exist and what ... More
Far-Ultraviolet Surveys of Globular Clusters: Hunting for the Products of Stellar Collisions and Near MissesJul 02 2004Globular clusters are gravitationally bound stellar systems containing on the order of 100,000 stars. Due to the high stellar densities in the cores of these clusters, close encounters and even physical collisions between stars are inevitable. These dynamical ... More
On the Calculation of QED Amplitudes in a Constant FieldJul 08 1998It is explained how first-quantized worldline path integrals can be used as an efficient alternative to Feynman diagrams in the calculation of QED amplitudes and effective actions. The examples include the one-loop photon splitting amplitude, the two-loop ... More
On the Stability of Contention Resolution Diversity Slotted ALOHAMar 21 2012In this paper a Time Division Multiple Access (TDMA) based Random Access (RA) channel with Successive Interference Cancellation (SIC) is considered for a finite user population and reliable retransmission mechanism on the basis of Contention Resolution ... More
Isotropy of Angular Frequencies and Weak Chimeras With Broken SymmetryDec 04 2015Oct 28 2016The notion of a weak chimeras provides a tractable definition for chimera states in networks of finitely many phase oscillators. Here we generalize the definition weak chimera to a more general class of equivariant dynamical systems by characterizing ... More
The Reeh-Schlieder property for ground statesJan 24 2000Feb 10 2000Recently it has been shown that the Reeh-Schlieder property w.r.t. thermal equilibrium states is a direct consequence of locality, additivity and the relativistic KMS condition. Here we extend this result to ground states.
Cluster Estimates for Modular StructuresApr 02 1998Apr 07 1999The basic ingredients of Tomita-Takesaki modular theory are used to establish cluster estimates. Applications to thermal quantum field theory are discussed.
Magnetoelectric bistabilities in ferromagnetic resonant tunneling structuresJul 28 2008The conditions for the occurrence of pronounced magnetoelectric bistabilities in the resonant tunneling through a ferromagnetic quantum well are theoretically investigated. The bistability appears due to the mutual feedback of the carriers Coulomb interaction ... More
Ricci curvature bounds for warped productsSep 06 2012Nov 09 2013We prove generalized lower Ricci curvature bounds for warped products over complete Finsler manifolds. On the one hand our result covers a theorem of Bacher and Sturm concerning euclidean and spherical cones. On the other hand it can be seen in analogy ... More
Obata's rigidity theorem for metric measure spacesOct 20 2014Apr 13 2015We prove Obata's rigidity theorem for metric measure spaces that satisfy a Riemannian curvature-dimension condition. Additionally, we show that a lower bound $K$ for the generalized Hessian of a sufficiently regular function $u$ holds if and only if $u$ ... More
Nominal Unification RevisitedDec 22 2010Nominal unification calculates substitutions that make terms involving binders equal modulo alpha-equivalence. Although nominal unification can be seen as equivalent to Miller's higher-order pattern unification, it has properties, such as the use of first-order ... More
Orthogonal bundles over curves in characteristic twoNov 11 2008Dec 09 2008Let X be a smooth projective curve of genus g \geq 2 defined over a field of characteristic two. We give examples of stable orthogonal bundles with unstable underlying vector bundles and use them to give counterexamples to Behrend's conjecture on the ... More
Auxiliary matrices on both sides of the equatorAug 12 2004Aug 17 2004The spectra of previously constructed auxiliary matrices for the six-vertex model at roots of unity are investigated for spin-chains of even and odd length. The two cases show remarkable differences. In particular, it is shown that for even roots of unity ... More
Lie algebraic structures in integrable models, affine Toda field theoryAug 25 2000Sep 01 2000The most prominent class of integrable quantum field theories in 1+1 dimensions is affine Toda theory. Distinguished by a rich underlying Lie algebraic structure these models have in recent years attracted much attention not only as test laboratories ... More
A Q-operator for the quantum transfer matrixOct 12 2006Oct 24 2006Baxter's Q-operator for the quantum transfer matrix of the XXZ spin-chain is constructed employing the representation theory of quantum groups. The spectrum of this Q-operator is discussed and novel functional relations which describe the finite temperature ... More
The characteristic polynomial of a random unitary matrix and Gaussian multiplicative chaos - The $L^2$-phaseOct 03 2014Oct 02 2015We study the characteristic polynomial of Haar distributed random unitary matrices. We show that after a suitable normalization, as one increases the size of the matrix, powers of the absolute value of the characteristic polynomial as well as powers of ... More
Exact asymptotics of the freezing transition of a logarithmically correlated random energy modelMay 12 2011Aug 26 2011We consider a logarithmically correlated random energy model, namely a model for directed polymers on a Cayley tree, which was introduced by Derrida and Spohn. We prove asymptotic properties of a generating function of the partition function of the model ... More
LHC Phenomenology of the Three-Site Higgsless ModelNov 08 2010We investigate the potential of the LHC for discovering the heavy vector and fermion resonances present in the Three-Site Higgsless Model. To this end, the model was implemented into the WHIZARD parton-level Monte Carlo eventgenerator. The results of ... More
On quasi-normal modes, area quantization and Bohr correspondence principleMar 18 2015Mar 30 2015In Int. Journ. Mod. Phys. D 14, 181 (2005), the author Khriplovich verbatim claims that "the correspondence principle does not dictate any relation between the asymptotics of quasinormal modes and the spectrum of quantized black holes" and that "this ... More
Bohr-like black holesMar 11 2015The idea that black holes (BHs) result in highly excited states representing both the "hydrogen atom" and the "quasi-thermal emission" in quantum gravity is today an intuitive but general conviction. In this paper it will be shown that such an intuitive ... More
Gravitational Waves Astronomy: a cornerstone for gravitational theoriesJun 28 2010Realizing a gravitational wave (GW) astronomy in next years is a great challenge for the scientific community. By giving a significant amount of new information, GWs will be a cornerstone for a better understanding of gravitational physics. In this paper ... More
An oscillating Universe from the linearized R^{2} theory of gravityFeb 18 2008Feb 19 2008An oscillating Universe which arises from the linearized R^{2} theory of gravity is discussed, showing that some observative evidences like the cosmological redshift and the Hubble law are in agreement with the model. In this context Dark Energy is seen ... More
Massive gravitational waves from the R^2 theory of gravity: production and response of interferometersNov 30 2007We show that from the R^{2} high order gravity theory it is possible to produce, in the linearized approch, particles which can be seen like massive modes of gravitational waves (GWs). The presence of the mass generates a longitudinal force in addition ... More
The Virgo - MiniGRAIL cross correlation for the detection of scalar gravitational wavesJun 26 2007Jul 05 2007After a review of the frequency - dependent angular pattern of interferometers in the TT gauge for scalar gravitational waves (SGWs), which has been recently analysed by Capozziello and Corda, in this letter the result is used to study the cross correlation ... More
Extension of the frequency-range of interferometers for the ''magnetic'' components of gravitational waves?Oct 31 2006Mar 26 2007Recently, with an enlighting treatment, Baskaran and Grishchuk have shown the presence and importance of the so-called ``magnetic'' components of gravitational waves (GWs), which have to be taken into account in the context of the total response functions ... More
Quasi-normal modes: the "electrons" of black holes as "gravitational atoms"? Implications for the black hole information puzzleFeb 26 2015Mar 31 2015Some recent important results on black hole (BH) quantum physics concerning the BH effective state and the natural correspondence between Hawking radiation and BH quasi-normal modes (QNMs) are reviewed, clarified and refined. Such a correspondence permits ... More
Quantum transitions of minimum energy for Hawking quanta in highly excited black holes: problems for loop quantum gravity?Dec 03 2012Dec 12 2013By analysing some recent results by Yoon, which arise from loop quantum gravity and from the assumption of the locality of photon emission in a black hole, we argue that they are not consistent with our recent semi-classical results for highly excited ... More
Effective temperature, Hawking radiation and quasinormal modesMay 17 2012Parikh and Wilczek have shown that Hawking radiation's spectrum cannot be strictly thermal. Such a non-strictly thermal character implies that the spectrum is also not strictly continuous and thus generates a natural correspondence between Hawking radiation ... More
General relativity and OPERA ExperimentJan 21 2012Nov 08 2012In his paper "A very simple solution to the OPERA neutrino velocity problem" the author J. Manuel Garcia-Islas claims to have very easily solved and explained within the general theory of relativity that OPERA's neutrinos are not traveling faster than ... More
A clarification on a common misconception about interferometric detectors of gravitational wavesMar 24 2011The aims of this letter are two. First, to show the angular gauge-invariance on the response of interferometers to gravitational waves (GWs). In this process, after resuming for completeness results on the Transverse-Traceless (TT) gauge, where, in general, ... More