Results for "Maria Lugaro"

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Advances in s-process modelsOct 01 2000Within the framework of the current models for the slow neutron capture (s) process in Asymptotic Giant Branch (AGB) stars we explore the uncertainties introduced by the assumptions made on stellar modeling. On the basis of star models constructed with ... More
On the internal pollution mechanisms in the globular cluster NGC 6121 (M4): heavy-element abundances and AGB modelsApr 25 2013Globular clusters display significant variations in their light-element content, pointing to the existence of a second stellar generation formed from the ejecta of an earlier generation. The nature of these internal polluters is still a matter of debate: ... More
The consequences of a nearby supernova on the early Solar SystemFeb 12 2018If the Sun was born in a relatively compact open cluster (half-mass radius ~3pc) with ~10^3 stars, it is quite likely that a massive (>10MSun) star was nearby when it exploded in a supernova. The repercussions of a supernova can be rather profound, and ... More
Radioactivities in Low- and Intermediate-Mass StarsOct 07 2010Oct 26 2010Energy in stars is provided by nuclear reactions, which, in many cases, produce radioactive nuclei. When stable nuclei are irradiated by a flux of protons or neutrons, capture reactions push stable matter out of stability into the regime of unstable species. ... More
Stellar yields from metal-rich asymptotic giant branch modelsApr 07 2016We present new theoretical stellar yields and surface abundances for three grids of metal-rich asymptotic giant branch (AGB) models. Post-processing nucleosynthesis results are presented for stellar models with initial masses between 1$M_{\odot}$ and ... More
Heavy element abundances in planetary nebulae: A theorist's perspectiveSep 28 2009The determination of heavy element abundances from planetary nebula (PN) spectra provides an exciting opportunity to study the nucleosynthesis occurring in the progenitor asymptotic giant branch (AGB) star. We perform post-processing calculations on AGB ... More
The s-process in rotating AGB starsFeb 04 2002We discuss the occurrence of the s-process during the radiative interpulse phase of rotating AGB stars. Due to differential rotation, protons are mixed into C12-rich layers after thermal pulses, in the course of the so called third dredge up episode. ... More
The s-Process in Rotating Asymptotic Giant Branch StarsMay 26 2003(abridged) We model the nucleosynthesis during the thermal pulse phase of a rotating, solar metallicity AGB star of 3M_sun. Rotationally induced mixing during the thermal pulses produces a layer (~2E-5M_sun) on top of the CO-core where large amounts of ... More
Mixing and the s-process in rotating AGB starsFeb 14 2003We model the nucleosynthesis during a radiative interpulse phase of a rotating 3Msun Asymptotic Giant Branch (AGB) star. We find an enhanced production of the neutron source species C13 compared to non-rotating models due to shear mixing of protons and ... More
Germanium Production in Asymptotic Giant Branch stars: Implications for Observations of Planetary NebulaeJan 16 2007Observations of planetary nebulae (PNe) by Sterling, Dinerstein and Bowers have revealed abundances in the neutron-capture element Germanium (Ge) from solar to factors of 3 -- 10 above solar. The enhanced Ge is an indication that the slow-neutron capture ... More
Fe-deficiency in H-deficient post-AGB stars due to n-capture nucleosynthesisFeb 07 2002H-deficient post-AGB objects, e.g. PG1159 type star K1-16 and born-again AGB star Sakurai's object, have been reported to be significantly iron-deficient. We find that the iron deficiencies expected due to neutron-capture nucleosynthesis during either ... More
Reaction Rate Uncertainties: NeNa and MgAl in AGB StarsJul 24 2006We study the effect of uncertainties in the proton-capture reaction rates of the NeNa and MgAl chains on nucleosynthesis due to the operation of hot bottom burning (HBB) in intermediate-mass asymptotic giant branch (AGB) stars. HBB nucleosynthesis is ... More
The intermediate neutron-capture process and carbon-enhanced metal-poor starsAug 30 2016Carbon-enhanced metal-poor (CEMP) stars in the Galactic Halo display enrichments in heavy elements associated with either the s (slow) or the r (rapid) neutron-capture process (e.g., barium and europium respectively), and in some cases they display evidence ... More
Evolution and nucleosynthesis of extremely metal-poor and metal-free low- and intermediate-mass stars II. s-process nucleosynthesis during the core He flashOct 11 2010Models of primordial and hyper-metal-poor stars with masses similar to the Sun experience an ingestion of protons into the hot core during the core helium flash phase at the end of their red giant branch evolution. This produces a concurrent secondary ... More
The s process in asymptotic giant branch stars of low metallicity and the composition of carbon-enhanced metal-poor starsDec 13 2011We present models for the slow neutron-capture process (s process) in asymptotic giant branch (AGB) stars of metallicity [Fe/H]=-2.3 and masses 0.9 Msun to 6 Msun. We encountered different regimes of neutron-capture nucleosynthesis increasing in importance ... More
Si Isotopic Ratios in Mainstream Presolar SiC Grains RevisitedAug 06 1999Although mainstream SiC grains, the major group of presolar SiC grains found in meteorites, are believed to have originated in the expanding envelope of asymptotic giant branch (AGB) stars during their late carbon-rich phases, their Si isotopic ratios ... More
Can Galactic chemical evolution explain the oxygen isotopic variations in the Solar System?Sep 11 2012A number of objects in primitive meteorites have oxygen isotopic compositions that place them on a distinct, mass-independent fractionation line with a slope of one on a three-isotope plot. The most popular model for describing how this fractionation ... More
Heavy Element Nucleosynthesis in the Brightest Galactic Asymptotic Giant Branch starsMar 13 2012Apr 18 2012We present updated calculations of stellar evolutionary sequences and detailed nucleosynthesis predictions for the brightest asymptotic giant branch (AGB) stars in the Galaxy with masses between 5Msun to 9Msun, with an initial metallicity of Z =0.02 ([Fe/H] ... More
A New Astrophysical Interpretation of the Si and Ti Isotopic Compositions of Mainstream SiC Grains from Primitive MeteoritesSep 16 1998Mainstream presolar SiC grains from primitive meteorites show a clear s-process signature in the isotopic composition of heavy trace elements. These grains most likely condensed in the winds of a variety of AGB stars. However, the non-solar and correlated ... More
Could SiC A+B grains have originated in a post-AGB thermal pulse?Feb 07 2002The carbon and nitrogen isotopic ratios of pre-solar SiC grains of type A+B suggest a proton-limited nucleosynthetic process as encountered, for instance, during the very late thermal pulse of post-AGB stars. We study the nuclear processes during this ... More
Cosmological implications of dwarf spheroidal chemical evolutionFeb 22 2006Apr 10 2006The chemical properties of dwarf spheroidals in the local group are shown to be inconsistent with star formation being truncated after the reionization epoch (z~8). Enhanced levels of [Ba/Y] in stars in dwarf spheroidals like Sculptor indicate strong ... More
HR4049: signature of nova nucleosynthesis ?Aug 16 2004The post-Asymptotic Giant Branch (AGB) star HR4049 is in an eccentric binary system with a relatively short period probably surrounded by a dusty circumbinary disk. Extremely anomalous oxygen isotopic ratios, O16/O17 ~ O16/O18 ~ 7, have been measured ... More
Decoding the message from meteoritic stardust silicon carbide grainsApr 15 2013Micron-sized stardust grains that originated in ancient stars are recovered from meteorites and analysed using high-resolution mass spectrometry. The most widely studied type of stardust is silicon carbide (SiC). Thousands of these grains have been analysed ... More
Nucleosynthesis Predictions for Intermediate-Mass AGB Stars: Comparison to Observations of Type I Planetary NebulaeSep 08 2008Type I planetary nebulae (PNe) have high He/H and N/O ratios and are thought to be descendants of stars with initial masses of ~3-8Msun. These characteristics indicate that the progenitor stars experienced proton-capture nucleosynthesis at the base of ... More
Origin of the p-process radionuclides 92Nb and 146Sm in the early Solar System and inferences on the birth of the SunJan 22 2016The abundances of 92Nb and 146Sm in the early Solar System are determined from meteoritic analysis and their stellar production is attributed to the p process. We investigate if their origin from thermonuclear supernovae deriving from the explosion of ... More
s-Process Nucleosynthesis in AGB Stars: A Test for Stellar EvolutionDec 16 2002[abridged] We study the s-process in AGB stars using three different stellar evolutionary models computed for a 3Msun and solar metallicity star. First we investigate the formation and the efficiency of the main neutron source. We parametrically vary ... More
The impact of the 18F(a,p)21Ne reaction on fluorine production in AGB starsDec 11 2008The recent experimental evaluation of the 18F(a,p)21Ne reaction rate, when considering its associated uncertainties, presented significant differences compared to the theoretical Hauser-Feshbach rate. This was most apparent at the low temperatures relevant ... More
The impact of the 18F(a,p)21Ne reaction on asymptotic giant branch nucleosynthesisDec 18 2007We present detailed models of low and intermediate-mass asymptotic giant branch (AGB) stars with and without the 18F(a,p)21Ne reaction included in the nuclear network, where the rate for this reaction has been recently experimentally evaluated for the ... More
Europium s-process signature at close-to-solar metallicity in stardust SiC grains from AGB starsMar 24 2013Individual mainstream stardust silicon carbide (SiC) grains and a SiC-enriched bulk sample from the Murchison carbonaceous meteorite have been analyzed by the Sensitive High Resolution Ion Microprobe - Reverse Geometry (SHRIMP-RG) for Eu isotopes. The ... More
Evolution and nucleosynthesis of helium-rich asymptotic giant branch modelsJul 02 2015There is now strong evidence that some stars have been born with He mass fractions as high as $Y \approx 0.40$ (e.g., in $\omega$ Centauri). However, the advanced evolution, chemical yields, and final fates of He-rich stars are largely unexplored. We ... More
Reaction Rates Uncertainties and the Production of F19 in AGB StarsJul 27 2004We present nucleosynthesis calculations and the resulting 19F stellar yields for a large set of models with different masses and metallicity. We find that the production of fluorine depends on the temperature of the convective pulses, the amount of primary ... More
The impact of updated Zr neutron-capture cross sections and new asymptotic giant branch models on our understanding of the s process and the origin of stardustNov 12 2013We present model predictions for the Zr isotopic ratios produced by slow neutron captures in C-rich asymptotic giant branch (AGB) stars of masses 1.25 to 4 Msun and metallicities Z=0.01 to 0.03, and compare them to data from single meteoritic stardust ... More
Rubidium abundances in the globular clusters NGC 6752, NGC 1904 and NGC 104 (47 Tuc)Aug 22 2013Large star-to-star variations of the abundances of proton-capture elements, such as Na and O, in globular clusters (GCs) are interpreted as the effect of internal pollution resulting from the presence of multiple stellar populations. To better constrain ... More
Short-lived radioactivity in the early Solar System: the Super-AGB star hypothesisAug 29 2012The composition of the most primitive Solar System condensates, such as calcium-aluminum-rich inclusions (CAI) and micron-sized corundum grains, show that short-lived radionuclides (SLR), e.g., 26Al, were present in the early Solar System. Their abundances ... More
Fluorine variations in the globular cluster NGC 6656 (M22): implications for internal enrichment timescalesOct 29 2012Nov 17 2012Observed chemical (anti)correlations in proton-capture elements among globular cluster stars are presently recognized as the signature of self-enrichment from now extinct, previous generations of stars. This defines the multiple population scenario. Since ... More
Stellar origin of the 182Hf cosmochronometer and the presolar history of solar system matterAug 09 2014Among the short-lived radioactive nuclei inferred to be present in the early solar system via meteoritic analyses, there are several heavier than iron whose stellar origin has been poorly understood. In particular, the abundances inferred for 182Hf (half-life ... More
The Role of Massive Agb Stars in the Early Solar System CompositionDec 23 2008We demonstrate that a massive asymptotic giant branch (AGB) star is a good candidate as the main source of short-lived radionuclides in the early solar system. Recent identification of massive (4-8 solar masses) AGB stars in the Galaxy, which are both ... More
The effect of the 19F(alpha,p)22Ne reaction rate uncertainty on the yield of fluorine from Wolf-Rayet StarsApr 06 2005In the light of recent recalculations of the \el{19}{F}(alpha,p)\el{22}{Ne} reaction rate we present results of the expected yield of \el{19}{F} from Wolf-Rayet (WR) stars. We have computed models using the upper and lower limits for the rate in addition ... More
Realization and Extension of Abstract Operation Contracts for Program LogicJan 18 2015For engineering software with formal correctness proofs it is crucial that proofs can be efficiently reused in case the software or its specification is changed. Unfortunately, in reality even slight changes in the code or its specification often result ... More
Continued Fraction Expansions of Matrix EigenvectorsOct 11 2008We examine various properties of the continued fraction expansions of matrix eigenvector slopes of matrices from the SL(2, Z) group. We calculate the average period length, maximum period length, average period sum, maximum period sum and the distributions ... More
Numerical methods for checking the regularity of subdivision schemesFeb 10 2012In this paper, motivated by applications in computer graphics and animation, we study the numerical methods for checking $C^k-$regularity of vector multivariate subdivision schemes with dilation 2I. These numerical methods arise from the joint spectral ... More
Weyl denominator identity for finite-dimensional Lie superalgebrasMay 08 2009Jul 26 2010Weyl denominator identity for finite-dimensional Lie superalgebras, conjectured by V.~Kac and M.~Wakimoto in 1994, is proven.
Weyl denominator identity for affine Lie superalgebras with non-zero dual Coxeter numberNov 30 2009Weyl denominator identity for the affinization of a basic Lie superalgebra with a non-zero Killing form was formulated by Kac and Wakimoto and was proven by them in defect one case. In this paper we prove this identity.
A Multiquadratic Field Generalization of Artin's ConjectureFeb 15 2012Sep 08 2014We prove that (under the assumption of the generalized Riemann hypothesis) a totally real multiquadratic number field $K$ has a positive density of primes $p \in \mathbb{Z}$ for which the image of the unit group $(\mathcal{O}_K)^{\times})$ in $(\mathcal{O}_K/p\mathcal{O}_K)^{\times})$ ... More
Darboux points and integrability of homogeneous Hamiltonian systems with three and more degrees of freedomMar 29 2009We consider natural complex Hamiltonian systems with $n$ degrees of freedom given by a Hamiltonian function which is a sum of the standard kinetic energy and a homogeneous polynomial potential $V$ of degree $k>2$. The well known Morales-Ramis theorem ... More
A cancellation-free formula for the Schur elements of the Ariki-Koike algebraJan 07 2011Schur elements play a powerful role in the representation theory of symmetric algebras. In the case of the Ariki-Koike algebra, Schur elements are Laurent polynomials whose factors determine when Specht modules are projective irreducible and whether the ... More
Collider Experiment: Strings, Branes and Extra DimensionsMay 12 2003May 18 2003Selected topics showcasing the exploration for new physics using colliders; presented at TASI 2001.
The (g-2)_mu data and the lightest Higgs boson in 2HDM(II)Dec 07 2001Dec 09 2001The present limits on the lightest Higgs boson in 2HDM (II) in light of the new E821 measurement of g-2 for the muon are discussed.
ECFA-Summary: Higgs, gamma-gamma and e-gamma physicsDec 24 2003Recent results obtained within ECFA/DESY and ECFA Study by the Higgs and gamma gamma /e gamma physics working groups are presented.
The new (g-2) for muon measurement and limits on the light Higgs bosons in 2HDM (II)Mar 20 2001Oct 01 2001We discuss how new data for a_{mu}= (g-2)_{mu}/2 improve constraints on new physics. Using two types of estimations of a_{mu}^{had} (Davier & H"{o}cker (case A) and Jegerlehner2000 (case B)) we evaluate 95% CL intervals for a new contribution, which can ... More
The Structure of the Photon in Hard Hadronic ProcessesDec 24 1997The concept of the structure of the photon is discussed and the progress in the measurement of various structure functions of the photon as well of parton distributions in the photon is shortly reviewed.
Status of 2HDM with a Light Higgs ParticleDec 24 1996Present data do not rule out the light neutral Higgs particle h or A with mass below 40--50 GeV in the framework of the general 2HDM ("Model II"). The status of this model in a light of existing LEP I data and a potential of the new muon experiment (g-2), ... More
Are bottom PDFs needed at the LHC?Jul 21 2014Processes involving bottom quarks play a crucial role in the LHC phenomenology, from flavour physics to Higgs characterisation and as a window to new physics, appearing both as signals and irreducible background in BSM searches. These processes can be ... More
NNLO analysis of the LHC W lepton charge asymmetry dataOct 11 2011The reweighting method presented in earlier publications is applied for incorporating the LHC W lepton asymmetry data published in 2010 into the NNPDF2.1 NNLO analysis. We confirm the result of the NLO analysis which indicated that these data reduce PDF ... More
Renewal processes with costs and rewardsApr 22 2014We review the theory of renewal reward processes, which describes renewal processes that have some cost or reward associated with each cycle. We present a new simplified proof of the renewal reward theorem that mimics the proof of the elementary renewal ... More
A Radon-Nikodym theorem for completely multi-positive linear maps and applicationsOct 04 2005052<p type="texpara" tag="Body Text" et="abstract" >A completely $n$ -positive linear map from a locally $C^{\ast}$-algebra $A$ to another locally $C^{\ast}$-algebra $B $is an $n\times n$ matrix whose elements are continuous linear maps from $A$ to $B$ ... More
On Hilbert modules over locally C*-algebras IIAug 02 2005In this paper we study the unitary equivalence between Hilbert modules over a locally C*-algebra. Also, we prove a stabilization theorem for countably generated modules over an arbitrary locally C*-algebra and show that a Hilbert module over a Frechet ... More
Edge Universality for Orthogonal Ensembles of Random MatricesDec 17 2008We prove edge universality of local eigenvalue statistics for orthogonal invariant matrix models with real analytic potentials and one interval limiting spectrum. Our starting point is the result of \cite{S:08} on the representation of the reproducing ... More
The Higgs System in and Beyond the Standard ModelJan 28 2014After the discovery of the Higgs boson particle on the 4th of July of 2012 at the Large Hadron Collider, sited at the european CERN laboratory, we are entering in a fascinating period for Particle Physics where both theorists and experimentalists are ... More
Boundedness of derivatives and anti-derivatives of holomorphic functions as a rare phenomenonNov 16 2016In this article we prove a general result which in particular suggests that, on a simply connected domain in C, all the derivatives and anti-derivatives of the generic holomorphic function are unbounded. A similar result holds for the operator of partial ... More
Hilbert-Schmidt groups as infinite-dimensional Lie groups and their Riemannian geometryJun 14 2005We describe the exponential map from an infinite-dimensional Lie algebra to an infinite-dimensional group of operators on a Hilbert space. Notions of differential geometry are introduced for these groups. In particular, the Ricci curvature, which is understood ... More
Crossed products of locally C*-algebrasDec 06 2005The crossed products of locally C*-algebras are defined and a Takai duality theorem for inverse limit actions of a locally compact group on a locally C*-algebra is proved.
Introduction to Astrophysics of MicroquasarsJun 29 2005The Astrophysics of microquasars - galactic miniatures of the far distant quasars - has become one of the most active fields of modern Astronomy in recent years. Here I review the astronomical methods used for the investigation of these objects, from ... More
Human Factors of Formal MethodsApr 29 2014This paper provides a brief introduction to the work that aims to apply the achievements within the area of engineering psychology to the area of formal methods, focusing on the specification phase of a system development process.
On rational blow-downs in Heegaard-Floer homologySep 29 2007Motivated by a result of L.P. Roberts on rational blow-downs in Heegaard-Floer homology, we study such operations along 3-manifolds that arise as branched double covers of $S^{3}$ along several non-alternating, slice knots.
Rouquier blocks of the cyclotomic Ariki-Koike algebrasApr 12 2008Oct 13 2008The definition of Rouquier for the families of characters of Weyl groups in terms of blocks of the associated Iwahori-Hecke algebra has made possible the generalization of this notion to the complex reflection groups. Here we give an algorithm for the ... More
Rouquier blocks of the cyclotomic Hecke algebras of G(de,e,r)May 02 2008Nov 26 2009The "Rouquier blocks" of the cyclotomic Hecke algebras, introduced by Rouquier, are a substitute for the "families of characters", defined by Lusztig for Weyl groups, which can be applied to all complex reflection groups. In this article, we determine ... More
Photon and its hadronic interactionDec 24 2003A short overview of basics aspects of hadronic interaction of the photon is presented.
Looking for a Light Higgs Particle at Present and Future CollidersSep 25 1996Present data do not rule out the light neutral Higgs particle $h$ or $A$ with mass below 40--50 GeV in the framework of the general 2HDM ("Model II"). The recent limits from LEP I on the parameters of the model, based on the Bjorken process $Z \to Z h$, ... More
Precision muon g-2 results and light Higgs bosons in the 2HDM(II)Aug 07 2002Aug 24 2002We discuss the implications of the recent evaluations of the SM contribution to a_mu=(g-2)_mu/2 in the light of the latest E821 measurement, which indicate \~ 3 sigma deviation. We derive the 95 % CL interval, delta a_mu, to be used to constrain any additional ... More
Constraints on the Higgs Sector from Processes Involving PhotonsDec 31 1998The Higgs sector of the Standard Model and of the Two Higgs Doublet Extensions of SM, MSSM and the general 2HDM, can be tested in processes involving photons. A short review of the corresponding results is presented.
Where is the Higgs boson?Dec 24 1998The status of the Higgs boson search in the Standard Model and beyond it is presented.
Two Higgs Doublet ModelsJul 09 1996Present data do not rule out the light neutral Higgs particle $h$ or $A$ in the framework of the general 2HDM. The discovery reach/exclusion limits of the Yukawa process $Z\rightarrow f {\bar f} h/A$, ($f= b$ quark or $\tau$ lepton) at LEP I and of the ... More
Network model of human languageSep 19 2007The phenomenon of human language is widely studied from various points of view. It is interesting not only for social scientists, antropologists or philosophers, but also for those, interesting in the network dynamics. In several recent papers word web, ... More
Shuffle bialgebrasMar 14 2007Dec 12 2008The goal of our work is to study the spaces of primitive elements of the Hopf algebras associated to the permutaedra and the associaedra. We introduce the notion of shuffle and preshuffle bialgebras, and compute the subpaces of primitive elements associated ... More
Analysis on harmonic extensions of H-type groupsMar 18 2015The subject of this PhD thesis is harmonic analysis on solvable extensions of H-type groups. Let N be an H-type group and S=NA be its solvable extension of rank one. The author study the weak type 1 boundedness of suitable Hardy-Littlewood maximal functions ... More
The Area Formula for Lipschitz Mappings of Carnot--Carathéodory SpacesOct 25 2011We prove the sub-Riemannian analog of the area formula for Lipschitz (in sub-Riemannian sense) mappings of equiregular Carnot--Carath\'{e}odory spaces.
Weyl denominator identity for the affine Lie superalgebra gl(2|2)^Jul 25 2010We prove the Weyl denominator identity for the affine Lie superalgebra gl(2|2)^ conjectured by V. Kac and M. Wakimoto. As it was pointed out in their paper, this gives another proof of Jacobi identity for the number of presentations of a given integer ... More
Uniform distribution of sequences of points and partitionsJun 24 2014The interest for uniformly distributed (u.d.) sequences of points, in particular for sequences with small discrepancy, arises from various applications. For instance, low-discrepancy sequences, which are sequences with a discrepancy of order $((\log N)^d)/N$ ... More
On models of non-Eucludian spaces generated by associative algebrasDec 09 2009We present the non-trivial example how to generate non-Euclidean geometries from associative unital algebras. We consider bundles of the sphere of the degenerate non-Eucleadian space and its two models. The first (conformal) model is obtained by the mapping ... More
Representations of the Yokonuma-Temperley-Lieb algebraFeb 28 2013Nov 25 2013We determine the representations of the Yokonuma-Temperley-Lieb algebra, which is defined as a quotient of the Yokonuma-Hecke algebra by generalising the construction of the classical Temperley-Lieb algebra.
Random networks with preferential growth and vertex deathSep 23 2015A dynamic model for a random network evolving in continuous time is defined where new vertices are born and existing vertices may die. The fitness of a vertex is defined as the accumulated in-degree of the vertex and a new vertex is connected to an existing ... More
On Euler characteristics of Selmer groups for abelian varieties over global function fieldsDec 07 2015Let $F$ be a global function field of characteristic $p>0$, $K/F$ an $\ell$-adic Lie extension ($\ell\neq p$) and $A/F$ an abelian variety. We provide Euler characteristic formulas for the $Gal(K/F)$-module $Sel_A(K)_\ell$.
Variance of $\mathcal{B}$-free integers in short intervalsDec 01 2015We prove some new statements on the distribution of $\mathcal{B}$-free numbers in short intervals. In particular, we show an asymptotic result for the variance of the number of $\mathcal{B}$-free integers in random short intervals which are, in some sense, ... More
It is not a Coincidence! On Curious Patterns in Calculus Optimization ProblemsMar 22 2016Jul 13 2016In this paper we consider a few Calculus optimization problems in which we notice peculiar patterns. In each of these cases there is a geometric explanation for the pattern showing that it is not just a coincidence.
Asymptotic shape in a continuum growth modelSep 23 2015A continuum growth model is introduced. The state at time $t$, $S_t$, is a subset of $\mathbb{R}^d$ and consists of a connected union of randomly sized Euclidean balls, which emerge from outbursts at their center points. An outburst occurs somewhere in ... More
Painlevé analysis for two 1D parabolic-parabolic models of chemotaxis; some travelling wave solutionsJul 01 2016In this paper we study the Painlev\'e analysis for two models of chemotaxis. We find that in some cases the reductions of these models in terms of travelling wave variable allow exact analytical solutions.
LLFR: A Lanczos-Based Latent Factor Recommender for Big Data ScenariosJun 14 2016The purpose if this master's thesis is to study and develop a new algorithmic framework for Collaborative Filtering to produce recommendations in the top-N recommendation problem. Thus, we propose Lanczos Latent Factor Recommender (LLFR); a novel "big ... More
Spatio-temporal features of FocusSTOct 25 2016In this technical report we summarise the spatio-temporal features and present the core operators of FocusST specification framework. We present the general idea of these operators, using a Steam Boiler System example to illustrate how the specification ... More
Isocurvature, non-gaussianity and the curvaton modelApr 07 2008Recent analyses of the statistical distribution of the temperature anisotropies in the CMB do not rule out the possibility that there is a large non-gaussian contribution to the primordial power spectrum. This fact motivates the re-analysis of the curvaton ... More
Analytic non-linearizable uniquely ergodic diffeomorphisms on the two-torusJun 05 2001Jun 18 2002We study the behavior of diffeomorphisms, contained in the closure $\bar {\A_\a}$ (in the inductive limit topology) of the set $\A_\a$ of real-analytic diffeomorphisms of the torus $\Bbb T^2$, conjugated to the rotation $R_\a:(x,y)\mapsto (x + \a, y)$ ... More
On Morita equivalence of group actions on locally C*-algebrasMay 25 2007We extend to the context of locally C*-algebras a result of F. Combes [Proc. London Math. Soc. 49(1984), 289-306].
Rational blow-down along Wahl type plumbing trees of spheresJul 24 2006Aug 22 2007We construct smooth 4-manifolds homeomorphic but not diffeomorphic to $CP^2#k\bar{CP^2},k \in {6,7,8,9}$, using the technique of rational blow-down along Wahl type plumbing trees of spheres.
The prime spectrum of a quantum Bruhat cell translateJul 08 1997Jul 10 1997The prime spectra of two families of algebras, $S^w$ and $\check{S}^w$, $w\in W,$ indexed by the Weyl group $W$ of a semisimple finitely dimensional are studied. The algebras $S^w$ have been introduced by A.~Joseph; they are $q$-analogues of the algebras ... More
The Two-Peak Model of LS I +61303: Radio Spectral Index AnalysisSep 10 2010The most puzzling aspect of the radio emission from LSI+61303 is that the large periodic radio outburst, with period equal to the orbital one, occurs very displaced from periastron passage, nearly at apoastron. In 1992, Taylor, one of the discoverers ... More
Closure properties of predicates recognized by deterministic and non-deterministic asynchronous automataOct 14 2010Let A be a finite alphabet and let L contained in (A*)^n be an n-variable language over A. We say that L is regular if it is the language accepted by a synchronous n-tape finite state automaton, it is quasi-regular if it is accepted by an asynchronous ... More
On a generic Verma module at the critical level over affine Lie superalgebrasApr 12 2005Jan 23 2007We describe the structure of a Verma module with a generic highest weight at the critical level over a symmetrizable affine Lie superalgebra not of the type A(2k,2l)^{(4)}. We obtain the character formula for a simple module with a generic highest weight ... More
Generalization of the "Stark unit" for abelian L-functions with multiple zerosDec 14 2008For an abelian extension of number fields we show that the Stark conjecture for all Artin L-functions with zero of order r is equivalent to existence of a special element in the rational span of the r-th exterior power of the Galois module of units of ... More
Bounding dimension of ambient space by density for mean curvature flowMar 01 2005For an ancient solution of the mean curvature flow, we show that each time slice M_t is contained in an affine subspace with dimension bounded in terms of the density and the dimension of the evolving submanifold. Recall that an ancient solution is a ... More
The 1D parabolic-parabolic Patlak-Keller-Segel model of chemotaxis: the particular integrable case and soliton solutionApr 27 2015Sep 28 2016In this paper we investigate the one-dimensional parabolic-parabolic Patlak-Keller-Segel model of chemotaxis. For the case when the diffusion coefficient of chemical substance is equal to two, in terms of travelling wave variables the reduced system appears ... More