Results for "J. L. Ortiz"

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Comment on "Quantum phase transition in the four-spin exchange antiferromagnet" by V. N. Kotov, D.-X. Yao, A. H. Castro-Neto, and D. K. CampbellMar 26 2010Oct 07 2010In a recent paper [Phys. Rev. {\bf B80}, 174403 (2009)] Kotov {\it et al.} studied the paramagnetic-to-antiferromagnetic transition in the $J$-$Q$ model. Their findings were claimed to be in "fairly good agreement" with previous quantum Monte-Carlo (QMC) ... More
FPGA implementation of a deep learning algorithm for real-time signal reconstruction in radiation detectors under high pile-up conditionsMar 06 2019The analog signals generated in the read-out electronics of radiation detectors are shaped prior to the digitization in order to improve the signal to noise ratio (SNR). The real amplitude of the analog signal is then obtained using digital filters, which ... More
Phase diagram of the Heisenberg antiferromagnet with four-spin interactionsMar 09 2009Dec 09 2009We study the quantum phase diagram of the Heisenberg planar antiferromagnet with a subset of four-spin ring exchange interactions, using the recently proposed heirarchical mean-field approach. By identifying relevant degrees of freedom, we are able to ... More
Hierarchical mean-field approach to the $J_1$-$J_2$ Heisenberg model on a square latticeSep 23 2008Jan 13 2009We study the quantum phase diagram and excitation spectrum of the frustrated $J_1$-$J_2$ spin-1/2 Heisenberg Hamiltonian. A hierarchical mean-field approach, at the heart of which lies the idea of identifying {\it relevant} degrees of freedom, is developed. ... More
Local physics of magnetization plateaux in the Shastry-Sutherland modelJun 26 2009Oct 21 2009We address the physical mechanism responsible for the emergence of magnetization plateaux in the Shastry-Sutherland model. By using a hierarchical mean-field approach we demonstrate that a plateau is stabilized in a certain {\it spin pattern}, satisfying ... More
New BVRI photometry results on KBOs from the ESO VLTDec 24 2008Dec 29 2008Photometric surveys of transNeptunian objects (TNOs) and Centaurs have suggested possible correlations between some orbital parameters and surface colors of classical objects, scattered disk objects (SDOs), and Centaurs. However, larger sample sizes are ... More
First determination of the temperature of a lunar impact flash and its evolutionJul 09 2018We report the first analysis of a flash produced by the impact of a meteoroid on the lunar surface and recorded both in the near-infrared and in the visible. Despite the fact that similar data have been recently published by other team during the refereeing ... More
Phase Transitions in Confined AntiferromagnetsFeb 16 2000Confinement effects on the phase transitions in antiferromagnets are studied as a function of the surface coupling v and the surface field h for bcc(110) films. Unusual topologies for the phase diagram are attained for particular combinations of v and ... More
Rotational properties of the binary and non-binary populations in the Trans-Neptunian beltJul 04 2014We present results for the short-term variability of Binary Trans-Neptunian Objects (BTNOs). We performed CCD photometric observations using the 3.58 m Telescopio Nazionale Galileo, the 1.5 m Sierra Nevada Observatory telescope, and the 1.23 m Centro ... More
Physical sectors of the confluent hypergeometric functions spaceMay 18 2001A relaxed factorization is used to obtain many of the properties obeyed by the confluent hypergeometric functions. Their implications on the analytical solutions of some interesting physical problems are also studied. It is quite remarkable that, although ... More
Refined Factorizations of Solvable PotentialsOct 08 1999A generalization of the factorization technique is shown to be a powerful algebraic tool to discover further properties of a class of integrable systems in Quantum Mechanics. The method is applied in the study of radial oscillator, Morse and Coulomb potentials ... More
Frustrated magnets and quantum paramagnetic phases at finite temperatureApr 11 2012Oct 04 2012We develop a general framework, which combines exact diagonalization in small clusters with a density matrix variational principle, to study frustrated magnets at finite temperature. This thermodynamic hierarchical mean-field technique is used to determine ... More
Differential Equivariant K-TheoryMay 04 2009Jun 01 2009Following Hopkins and Singer, we give a definition for the differential equivariant K-theory of a smooth manifold acted upon by a finite group. The ring structure for differential equivariant K-theory is developed explicitly. We also construct a pushforward ... More
What is a Cooper pair ?Apr 09 2006Recently, the nature of Cooper pairs in the BCS-BEC crossover has regained attention due to the observation of a large fraction of preformed fermion pairs on the BCS side of the Feshbach resonance in ultracold atomic Fermi gases. While several theoretical ... More
An Analysis of the Quasicontinuum MethodMar 22 2001The aim of this paper is to present a streamlined and fully three-dimensional version of the quasicontinuum (QC) theory of Tadmor et al. and to analyze its accuracy and convergence characteristics. Specifically, we assess the effect of the summation rules ... More
The Cooper pair from radio-frequency excitations in ultracold gasesMar 14 2008We discuss the concept of Cooper pair in the context of recent experimental studies of radio-frequency excitations in ultracold atomic gases. We argue that the threshold energy determines the size of the Cooper pair emergent from the exact solution of ... More
SAOLIM, a prototype of a low cost System for Adaptive Optics with Lucky ImagingJun 10 2010A prototype of a low cost Adaptive Optics (AO) system has been developed at the Instituto de Astrofisica de Andalucia (CSIC) and tested at the 2.2m telescope of the Calar Alto observatory. We present here the status of the project, which includes the ... More
Ionization toward the high-mass star-forming region NGC 6334 IJun 13 2013Mar 20 2014Context. Ionization plays a central role in the gas-phase chemistry of molecular clouds. Since ions are coupled with magnetic fields, which can in turn counteract gravitational collapse, it is of paramount importance to measure their abundance in star-forming ... More
Discovery of weak 6.7-GHz CH3OH masers in a sample of high-mass Hi-GAL sourcesNov 04 2013Maser lines from different molecular species, including water, hydroxyl, and methanol, are common observational phenomena associated with massive star forming regions. In particular, the methanol maser appears as an ideal tool to study the early phases ... More
Engineering spin exchange in non-bipartite graphene zigzag edgesJun 02 2016Sep 15 2016The rules that govern spin exchange interaction in pristine graphene nanostructures are constrained by the bipartite character of the lattice, so that the sign of the exchange is determined by whether magnetic moments are on the same sublattice or else. ... More
The scientific impact of Einstein's visit to Argentina, in 1925Mar 11 2016The arrival of Albert Einstein in Argentina in 1925 had an impact, equally relevant, on the scientific community and on the general public. In this paper we discuss that visit from three different perspectives. Firstly, we consider the conditions that ... More
Einstein en la Argentina: el impacto cientifico de su visitaDec 26 2017We present a brief review of the impact that Albert Einstein's visit to Argentina had on the scientific community and on the general public. Among other particularities, his visit was, at a certain point, somewhat disconcerting: not only because of the ... More
Relativity in Argentine culture in the early twentieth centuryOct 08 2018In previous works we have considered various aspects of the reception of the theories of Albert Einstein in our country. In particular, we discussed the impact of his visit to Argentina in 1925, and the precise content of the conferences and scientific ... More
The supersymmetric modified Poschl-Teller and delta-well potentialsOct 04 1999New supersymmetric partners of the modified Poschl-Teller and the Dirac's delta well potentials are constructed in closed form. The resulting one-parametric potentials are shown to be interrelated by a limiting process. The range of values of the parameters ... More
Laser induced topological cues shape, guide, and anchor human Mesenchymal Stem CellsJan 25 2018This report focuses on the effect of the surface topography of the substrate on the behavior of human mesenchymal stem cells from bone marrow (MSCs) before and after co-differentiation into adipocytes and osteoblasts. Picosecond pulsed laser ablation ... More
Short-term variability of a sample of 29 trans-Neptunian objects and CentaursApr 27 2010We present results of 6 years of observations, reduced and analyzed with the same tools in a systematic way. We report completely new data for 15 objects, for 5 objects we present a new analysis of previously published results plus additional data and ... More
Thermodynamics of gravitational clustering phenomena: $N$-body self-gravitating gas on the sphere $\mathbb{S}^{3}\subset\mathbb{R}^{4}$Oct 07 2016This work is devoted to the thermodynamics of gravitational clustering, a collective phenomenon with a great relevance in the $N$-body cosmological problem. We study a classical self-gravitating gas of identical non-relativistic particles defined on the ... More
First echoes of relativity in Argentine astronomySep 17 2008We consider the attitude of astronomers in Argentina in connection with the new problems posed by relativity theory, before and after GR was presented. We begin considering the sequence of "technical" publications that appeared and use it to attempt to ... More
Electrical spin manipulation in graphene nanostructuresDec 20 2017We propose a mechanism to drive singlet-triplet spin transitions electrically, in a wide class of graphene nanostructures that present pairs of in-gap zero modes, localized at opposite sublattices. Examples are rectangular nanographenes with short zigzag ... More
Brick Walls and AdS/CFTNov 28 2011May 22 2014We discuss the relationship between the bulk-boundary correspondence in Rehren's algebraic holography (and in other 'fixed-background' approaches to holography) and in mainstream 'Maldacena AdS/CFT'. Especially, we contrast the understanding of black-hole ... More
Einstein's unpublished opening lecture for his course on relativity theory in Argentina, 1925Mar 11 2009In 1922 the University of Buenos Aires (UBA) Council approved a motion to send an invitation to Albert Einstein to visit Argentina and give a course of lectures on his theory of relativity. The motion was proposed by Jorge Duclout (1856-1927), who had ... More
The "inedito" of Einstein and his 1925 visit to Buenos AiresJun 30 2008In an article published by Mauricio Nirenstein in 1925, a few months after the visit of Albert Einstein to Argentina, the author wrote various comments and references relative to the scientist's visit. In particular, Nirenstein mentioned a personal conversation ... More
Anti-positivism, theoretical sciences and relativity in the Argentina of the 1920sMar 20 2012Observing the early years of the 1920's, it is possible to detect a fracture in the perception of relativity theory in Argentina, characterized by the publication of a series of strictly scientific studies on this theory, in parallel with presentations ... More
Albert Einstein visits ArgentinaJun 06 2005This is a detailed, day by day, account of Albert Einstein's activities, both social and scientific, during his 30-day stay in Argentina in 1925, including his lectures on relativity at the various local universities and his visit to the National Academy ... More
Coordinated thermal and optical observations of Trans-Neptunian object (20000) Varuna from Sierra NevadaJun 27 2002We report on coordinated thermal and optical measurements of trans-Neptunian object (20000) Varuna obtained in January-February 2002, respectively from the IRAM 30-m and IAA 1.5 m telescopes. The optical data show a lightcurve with a period of 3.176+/-0.010 ... More
Lunar impact flashes from Geminids, analysis of luminous efficiencies and the flux of large meteoroids on EarthNov 23 2015We analyze lunar impact flashes recorded by our team during runs in December 2007, 2011, 2013 and 2014. In total, 12 impact flashes with magnitudes ranging between 7.1 and 9.3 in V band were identified. From these, 9 events could be linked to the Geminid ... More
Physical properties of centaur (54598) Bienor from photometryDec 08 2016We present time series photometry of Bienor in four observation campaigns from 2013 to 2016 and compare them with previous observations in the literature dating back to 2000. The results show a remarkable decline in the amplitude of the rotational light ... More
Locating the critical end point using the linear sigma model coupled to quarksDec 01 2017We use the linear sigma model coupled to quarks to compute the effective potential beyond the mean field approximation, including the contribution of the ring diagrams at finite temperature and baryon density. We determine the model couplings and use ... More
The Galactic O-Star Catalog (GOSC) and the Galactic O-Star Spectroscopic Survey (GOSSS): current statusOct 07 2016We present the updates of the Galactic O-Star Catalog (GOSC) that we have undertaken in the last two years: new spectral types, more objects, additional information, and coordination with CDS. We also present updates for the Galactic O-Star Spectroscopic ... More
Assessment of different formation scenarios for the ring system of (10199) CharikloMar 07 2017The discovery that the centaur (10199) Chariklo possesses a ring system opens questions about their origin. We here asses the plausibility of different scenarios for the origin of the observed ring system. We first consider the possibility that the material ... More
A photometric search for active Main Belt asteroidsJan 22 2014It is well known that some Main Belt asteroids show comet-like features. A representative example is the first known Main Belt comet 133P/(7968) Elst-Pizarro. If the mechanisms causing this activity are too weak to develop visually evident comae or tails, ... More
Short-term variability of 10 trans-Neptunian objectsJul 09 2012We present our latest results about the short-term variability of trans-Neptunian objects (TNOs). We performed broad-band CCD photometric observations using several telescopes in Spain and Chile. We present results based on three years of observations ... More
Search for bright nearby M dwarfs with Virtual Observatory toolsAug 07 2014Using Virtual Observatory tools, we cross-matched the Carlsberg Meridian 14 and the 2MASS Point Source catalogs to select candidate nearby bright M dwarfs distributed over ~ 25,000 deg^2. Here, we present reconnaissance low-resolution optical spectra ... More
Transneptunian objects and Centaurs from light curvesOct 08 2009Nov 05 2009We analyze a vast light curve database by obtaining mean rotational properties of the entire sample, determining the spin frequency distribution and comparing those data with a simple model based on hydrostatic equilibrium. For the rotation periods, the ... More
The Geminid meteoroid stream as a potential meteorite dropper: a case studySep 25 2013A Geminid fireball with an absolute magnitude of -13 was observed over the south of Spain on Dec. 15, 2009. This extraordinarily bright event (the brightest Geminid ever recorded by our team) was imaged from two meteor observing stations operated by the ... More
The Lower Algebraic K-Theory of Split Three-Dimensional Crystallographic GroupsNov 09 2012We explicitly compute the lower algebraic K-theory of the split three-dimensional crystallographic groups; i.e., the groups G that act properly and cocompactly on three-dimensional Euclidean space by isometries, such that the natural map from G to O(3) ... More
Scalable design of an IMS cross-flow micro-generator/ion detectorJul 30 2012Feb 14 2013Ion-mobility spectrometry (IMS) is an analytical technique used to separate and identify ionized gas molecules based on their mobility in a carrier buffer gas. Such methods come in a large variety of versions that currently allow ion identification at ... More
Young, active radio stars in the AB Doradus moving groupMar 26 2017Context. Precise determination of stellar masses is necessary to test the validity of pre-main-sequence (PMS) stellar evolutionary models, whose predictions are in disagreement with measurements for masses below 1.2 Msun. To improve such a test, and based ... More
Algebraic K-theory of hyperbolic 3-simplex reflection groupsMay 07 2007A hyperbolic 3-simplex reflection group is a Coxeter group arising as a lattice in the isometry group of hyperbolic 3-space, with fundamental domain a geodesic simplex (possibly with some ideal vertices). The classification of these groups is known, and ... More
A bilayer Double Semion Model with Symmetry-Enriched Topological OrderApr 29 2016Sep 14 2016We construct a new model of two-dimensional quantum spin systems that combines intrinsic topo- logical orders and a global symmetry called flavour symmetry. It is referred as the bilayer Doubled Semion model (bDS) and is an instance of symmetry-enriched ... More
Interpreting extracted rules from ensemble of trees: Application to computer-aided diagnosis of breast MRIJun 27 2016High predictive performance and ease of use and interpretability are important requirements for the applicability of a computer-aided diagnosis (CAD) to human reading studies. We propose a CAD system specifically designed to be more comprehensible to ... More
Tunable unconventional Kondo effect on topological insulator surfacesAug 23 2015Dec 08 2015We study Kondo physics of a spin-$\frac{1}{2}$ impurity in electronic matter with strong spin-orbit interaction, which can be realized by depositing magnetic adatoms on the surface of a three-dimensional topological insulator. We show that magnetic properties ... More
Quantum mechanical composition laws in reparameterization invariant systemsAug 20 1993This paper gives a brief description of the derivation of a composition law for the propagator of a relativistic particle, in a sum over histories quantization. The extension of this derivation to the problem of finding a composition law for quantum cosmology ... More
Bright Fireballs Associated with the Potentially Hazardous Asteroid 2007LQ19Jun 25 2014We analyze here two very bright fireballs produced by the ablation in the atmosphere of two large meteoroids in 2009 and 2010. These slow-moving and deep-penetrating events were observed over Spain in the framework of our Spanish Fireball Network continuous ... More
Bulk-boundary correspondence in three dimensional topological insulatorsFeb 28 2011Aug 10 2011We discuss the relation between bulk topological invariants and the spectrum of surface states in three dimensional non-interacting topological insulators. By studying particular models, and considering general boundary conditions for the electron wavefunction ... More
Unpublished opening lecture for the course on the theory of relativity in Argentina, 1925Mar 13 2009Honorable Rector, Honorable Professors, and Students of this University: In these times of political and economic struggle and nationalistic fragmentation, it is a particular joy for me to see people assembling here to give their attention exclusively ... More
Relating the Farrell Nil-groups to the Waldhausen Nil-groupsSep 25 2006We prove that the Waldhausen Nil-group associated to a virtually cyclic groups that surjects onto the infinite dihedral group vanishes if and only if the corresponding Farrell Nil-group associated to the canonical index two subgroup is trivial. The proof ... More
Relative hyperbolicity, classifying spaces, and lower algebraic K-theoryJun 19 2006For $\Gamma$ a relatively hyperbolic group, we construct a model for the universal space among $\Gamma$-spaces with isotropy on the family VC of virtually cyclic subgroups of $\Gamma$. We provide a recipe for identifying the maximal infinite virtually ... More
Splitting formulas for certain Waldhausen Nil-groupsNov 15 2007For a group G that splits as an amalgamation of A and B over a common subgroup C, there is an associated Waldhausen Nil-group, measuring the "failure" of Mayer-Vietoris for algebraic K-theory. Assume that (1) the amalgamation is acylindrical, and (2) ... More
Superconductivity in strongly repulsive fermions: the role of kinetic-energy frustrationMar 26 2010Oct 27 2010We discuss a physical mechanism of a non-BCS nature which can stabilize a superconducting state in a {\it strongly repulsive} electronic system. By considering the two-dimensional Hubbard model with spatially modulated electron hoppings, we demonstrate ... More
Tunneling measurement of quantum spin oscillationsDec 03 2002Jul 01 2003We consider the problem of tunneling between two leads via a localized spin 1/2 or any other microscopic system which can be modeled by a two-level Hamiltonian. We assume that a constant magnetic field ${\bf B}_0$ acts on the spin, that electrons in the ... More
Spectroscopy and Orbital Analysis of Bright Bolides Observed over the Iberian Peninsula from 2010 to 2012Aug 02 2013We present the analysis of the atmospheric trajectory and orbital data of four bright bolides observed over Spain, one of which is a potential meteorite dropping event. Their absolute magnitude ranges from -10 to -11. Two of these are of sporadic origin, ... More
Absolute colors and phase coefficients of trans-Neptunian objects: HV-HR and relative phase coefficientsAug 29 2018The trans-Neptunian objects (TNOs) are small Solar System bodies at large distances from the Sun. As such, their physical properties are difficult to measure. Accurate determination of their physical parameters is essential to model and theorize the actual ... More
Dynamical Manipulation for spin-1/2 SystemsJun 18 1997Nov 16 1998By means of the inverse techniques we analyse the evolution of purely spin-1/2 systems in homogeneous magnetic fields as well as the generation of exact solutions. Some ``evolution loops'', dynamical processes for which any state evolves cyclically, are ... More
Confinement Effects in AntiferromagnetsApr 11 2000Phase equilibrium in confined Ising antiferromagnets was studied as a function of the coupling (v) and a magnetic field (h) at the surfaces, in the presence of an external field H. The ground state properties were calculated exactly for symmetric boundary ... More
Stripes, topological order, and deconfinement in a planar t-Jz modelSep 10 2003Aug 17 2004We determine the quantum phase diagram of a two-dimensional bosonic t-Jz model as a function of the lattice anisotropy gamma, using a quantum Monte Carlo loop algorithm. We show analytically that the low-energy sectors of the bosonic and the fermionic ... More
Study of Pairing Correlations in the Attractive Hubbard Model on Chains, Ladders, and SquaresDec 07 1999We report the results of zero temperature quantum Monte Carlo simulations and zero temperature mean-field calculations of the attractive Hubbard model on chains, ladders, and square lattices. We investigated the predictability of the BCS approximation, ... More
Critical indices of random planar electrical networksJan 11 2005Aug 06 2008We propose a new method to estimate the critical index $t$ for strength of networks of random fused conductors. It relies on a recently introduced expression for their yield strength. We confirm the results using finite size scaling. To pursue this commitment, ... More
The 2011 October Draconids Outburst. II. Meteoroid Chemical Abundances from Fireball SpectroscopyApr 29 2013On October 8, 2011 the Earth crossed dust trails ejected from comet 21P/Giacobini-Zinner in the late 19th and early 20th Century. This gave rise to an outburst in the activity of the October Draconid meteor shower, and an international team was organized ... More
Correlated Wave-Functions and the Absence of Long Range Order in Numerical Studies of the Hubbard ModelSep 02 1998We present a formulation of the Constrained Path Monte Carlo (CPMC) method for fermions that uses trial wave-functions that include many-body effects. This new formulation allows us to implement a whole family of generalized mean-field states as constraints. ... More
Introduction to Quantum Information ProcessingJul 30 2002As a result of the capabilities of quantum information, the science of quantum information processing is now a prospering, interdisciplinary field focused on better understanding the possibilities and limitations of the underlying theory, on developing ... More
Evolution loops and spin-1/2 systemsOct 03 1999The derivation of a new family of magnetic fields inducing exactly solvable spin evolutions is presented. The conditions for which these fields generate the evolution loops (dynamical processes for which any spin state evolves cyclically) are studied. ... More
Peaks and jumps reconstruction with B-splines scaling functionsFeb 06 2013We consider a methodology based in B-splines scaling functions to numerically invert Fourier or Laplace transforms of functions in the space $L^2(\mathbb{R})$. The original function is approximated by a finite combination of $j^{th}$ order B-splines basis ... More
Haar Wavelets-Based Approach for Quantifying Credit Portfolio LossesApr 29 2009This paper proposes a new methodology to compute Value at Risk (VaR) for quantifying losses in credit portfolios. We approximate the cumulative distribution of the loss function by a finite combination of Haar wavelets basis functions and calculate the ... More
A Simple Power Analysis Attack on the Twofish Key ScheduleNov 22 2016This paper introduces an SPA power attack on the 8-bit implementation of the Twofish block cipher. The attack is able to unequivocally recover the secret key even under substantial amounts of error. An initial algorithm is described using exhaustive search ... More
Neutron background at the Canfranc Underground Laboratory and its contribution to the IGEX-DM dark matter experimentMar 04 2004Apr 07 2004A quantitative study of the neutron environment in the Canfranc Underground Laboratory has been performed. The analysis is based on a complete set of simulations and, particularly, it is focused on the IGEX-DM dark matter experiment. The simulations are ... More
Using Wavelets to reject background in Dark Matter experimentsFeb 16 2003A method based on wavelet techniques has been developed and applied to background rejection in the data of the IGEX dark matter experiment. The method is presented and described in some detail to show how it efficiently rejects events coming from noise ... More
Water-ice driven activity on Main-Belt Comet P/2010 A2 (LINEAR) ?Jun 30 2010The dust ejecta of Main-Belt Comet P/2010 A2 (LINEAR) have been observed with several telescopes at the at the Observatorio del Roque de los Muchachos on La Palma, Spain. Application of an inverse dust tail Monte Carlo method to the images of the dust ... More
Identifying Ultra-Cool Dwarfs at Low Galactic Latitudes: A Southern Candidate CatalogueApr 19 2012We present an Ultra-Cool Dwarf (UCD) catalogue compiled from low southern Galactic latitudes and mid-plane, from a cross-correlation of the 2MASS and SuperCOSMOS surveys. The catalogue contains 246 members identified from 5042 sq. deg. within 220 deg. ... More
Possible ring material around centaur (2060) ChironJan 23 2015We propose that several short duration events observed in past stellar occultations by Chiron were produced by rings material. From a reanalysis of the stellar occultation data in the literature we determined two possible orientations of the pole of Chiron's ... More
Rotational fission of Trans-Neptunian Objects. The case of HaumeaOct 17 2011We present several lines of evidence based on different kinds of observations to conclude that rotational fission has likely occurred for a fraction of the known Trans-Neptunian Objects (TNOs). It is also likely that a number of binary systems have formed ... More
Absolute magnitudes and phase coefficients of trans-Neptunian objectsNov 30 2015Context: Accurate measurements of diameters of trans-Neptunian objects are extremely complicated to obtain. Thermal modeling can provide good results, but accurate absolute magnitudes are needed to constrain the thermal models and derive diameters and ... More
FRW cosmological model inside an isolated Schwarzschild black holeJun 11 2004Using the canonical quantum theory of spherically symmetric pure gravitational systems, we present a direct correspondence between the Friedmann-Robertson-Walker (FRW) cosmological model in the interior of a Schwarzschild black hole and the nth energy ... More
A revised distance to IRAS 16293$-$2422 from VLBA astrometry of associated water masersFeb 09 2018IRAS 16293-2422 is a very well studied young stellar system seen in projection towards the L1689N cloud in the Ophiuchus complex. However, its distance is still uncertain with a range of values from 120 pc to 180 pc. Our goal is to measure the trigonometric ... More
Photometric and spectroscopic evidence for a dense ring system around Centaur CharikloJul 17 2014Jul 24 2014In this work we aim to study if the variability in the absolute magnitude of Chariklo and the temporal variation of the spectral ice feature, even its disappearance in 2007, can be explained by an icy ring system whose aspect angle changes with time. ... More
Analysis of the September $\varepsilon$-Perseid outburst in 2013Jul 17 2018We analyze the outburst experienced by the September $\varepsilon$-Perseid meteor shower on 9 September 2013. As a result of our monitoring the atmospheric trajectory of 60 multi-station events observed over Spain was obtained and accurate orbital data ... More
Tetrahedral Units: For Dodecahedral Super-StructuresFeb 24 2016Different novel organic-chemical possibilities for tetrahedral building units are considered, with attention to their utility in constructing different super-structures. As a representative construction we consider the use of sets of 20 such identical ... More
Issues and Observations on Applications of the Constrained-Path Monte Carlo Method to Many-Fermion SystemsJan 06 1999We report several important observations that underscore the distinctions between the constrained-path Monte Carlo method and the continuum and lattice versions of the fixed-node method. The main distinctions stem from the differences in the state space ... More
Generalizations of entanglement based on coherent states and convex setsJul 26 2002Unentangled pure states on a bipartite system are exactly the coherent states with respect to the group of local transformations. What aspects of the study of entanglement are applicable to generalized coherent states? Conversely, what can be learned ... More
Rational equivariant K-homology of low dimensional groupsDec 19 2011We consider groups G which have a cocompact, 3-manifold model for the classifying space \underline{E}G. We provide an algorithm for computing the rationalized equivariant K-homology of \underline{E}G. Under the additional hypothesis that the quotient ... More
Fluctuations in fluids in thermal nonequilibrium states below the convective Rayleigh-Benard instabilitySep 13 2001Starting from the linearized fluctuating Boussinesq equations we derive an expression for the structure factor of fluids in stationary convection-free thermal nonequilibrium states, taking into account both gravity and finite-size effects. It is demonstrated ... More
Extended Non-Thermal Emission Possibly Associated with Cyg OB2 #5Nov 28 2011Cyg OB2 #5 is a contact binary system (O6.5-7+O5.5-6) with associated radio continuum emission. Two compact ($\leq 0\rlap.{"}3$) radio continuum components have been reported previously: the primary one is associated with the contact binary and the secondary ... More
Backlund-type superposition and free particle n-susy partnersOct 03 1999The higher order susy partners of Schroedinger Hamiltonians can be explicitly constructed by iterating a nonlinear difference algorithm coinciding with the Backlund superposition principle used in soliton theory. As an example, it is applied in the construction ... More
VLBA Determination of the Distance to Nearby Star-forming Regions. VIII. The LkH$α$ 101 clusterJan 16 2018The LkH$\alpha$ 101 cluster takes its name from its more massive member, the LkH$\alpha$ 101star, which is an $\sim15$ M$_\odot$ star whose true nature is still unknown. The distance to the LkH$\alpha$ 101 cluster has been controversial for the last few ... More
Haumea's thermal emission revisited in the light of the occultation resultsNov 23 2018A recent occultation measurement of the dwarf planet Haumea (Ortiz et al. 2017) revealed an elongated shape with the longest axis comparable to Pluto's mean diameter. The chords also indicate a ring around Haumea's equatorial plane, where its largest ... More
Observation of light echoes around very young starsJul 14 2010Jul 16 2010The goal of the paper is to present new results on light echoes from young stellar objects. Broad band CCD images were obtained over three months at one-to-two week intervals for the field of NGC 6726, using the large field-of-view remotely-operated telescope ... More
The finite difference algorithm for higher order supersymmetryApr 05 2000The higher order supersymmetric partners of the Schroedinger's Hamiltonians can be explicitly constructed by iterating a simple finite difference equation corresponding to the Baecklund transformation. The method can completely replace the Crum determinants. ... More
A mid-term astrometric and photometric study of Trans-Neptunian Object (90482) OrcusOct 29 2010From CCD observations of a fixed and large star field that contained the binary TNO Orcus, we have been able to derive high-precision relative astrometry and photometry of the Orcus system with respect to background stars. The RA residuals of an orbital ... More
Magnetic and electronic properties at the gamma-Al2O3/SrTiO3 interfaceJan 28 2019The magnetic and electronic nature of the gamma-Al2O3/SrTiO3 spinel/perovskite interface is explored by means of x-ray absorption spectroscopy. Polarized x-ray techniques combined with atomic multiplet calculations reveal localized magnetic moments assigned ... More