State determination: an iterative algorithm

An iterative algorithm for state determination is presented that uses as physical input the probability distributions for the eigenvalues of two or more observables in an unknown state $\Phi$. Starting form an arbitrary state $\Psi_{0}$, a succession of states $\Psi_{n}$ is obtained that converges to $\Phi$ or to a Pauli partner. This algorithm for state reconstruction is efficient and robust as is seen in the numerical tests presented and is a useful tool not only for state determination but also for the study of Pauli partners. Its main ingredient is the Physical Imposition Operator that changes any state to have the same physical properties, with respect to an observable, of another state.Comment: 11 pages 3 figure

Quantum Gravity Hamiltonian for Manifolds with Boundary

In canonical quantum gravity, when space is a compact manifold with boundary there is a Hamiltonian given by an integral over the boundary. Here we compute the action of this `boundary Hamiltonian' on observables corresponding to open Wilson lines in the new variables formulation of quantum gravity. In cases where the boundary conditions fix the metric on the boundary (e.g., in the asymptotically Minkowskian case) one can obtain a finite result, given by a `shift operator' generating translations of the Wilson line in the direction of its tangent vector. A similar shift operator serves as the Hamiltonian constraint in Morales-T\'ecotl and Rovelli's work on quantum gravity coupled to Weyl spinors. This suggests the appearance of an induced field theory of Weyl spinors on the boundary, analogous to that considered in Carlip's work on the statistical mechanics of the 2+1-dimensional black hole.Comment: 17 pages in LaTeX format, vastly improved versio

Coarse-grained entanglement classification through orthogonal arrays

Classification of entanglement in multipartite quantum systems is an open problem solved so far only for bipartite systems and for systems composed of three and four qubits. We propose here a coarse-grained classification of entanglement in systems consisting of $N$ subsystems with an arbitrary number of internal levels each, based on properties of orthogonal arrays with $N$ columns. In particular, we investigate in detail a subset of highly entangled pure states which contains all states defining maximum distance separable codes. To illustrate the methods presented, we analyze systems of four and five qubits, as well as heterogeneous tripartite systems consisting of two qubits and one qutrit or one qubit and two qutrits.Comment: 38 pages, 1 figur

Modificación de un equipo de medición de absorción e impedancia acústica para adaptarlo a la norma ASTM C-384

La Sección Acústica y Vibraciones del LEMIT cuenta con un equipo marca Brüel & Kjaer, modelo 4002, que permite la rápida y fácil determinación de los coeficientes de absorción acústica. Al tratar de medir materiales con bajos coeficientes de absorción, aparecen ciertas incertidumbres en la lectura de los valores obtenidos, que ponen en evidencia la imposibilidad de obtener resultados confiables. Un análisis de este funcionamiento deficiente demostró que se producían excesivas vibraciones en el instrumento, introduciéndole una absorción a la del material a medir, lo cual mostró la convéniencia de rediseñar el equipo para adecuarlo a la medida de bajos coeficientes de absorción.The Acoustics and Vibration Laboratory of LEMIT has a Briiel & Kjaer instrument, model 4002, that allows the fast and easy determination of acoustic absorption coefficients. Trying to measuring materials with low coefficients there is some uncertainty in the obtaind values, that shows the impossibility of reliable results. An analysis of this deficiency shows that the instrument vibrates excessively introducing an additional absorption, pointing out the convenience of redesign the equipment to measure low absorption coefficients

Phylogeny and chromosomal diversification in the <i>Dichroplus elongatus</i> species group (Orthoptera, Melanoplinae)

In an attempt to track the chromosomal differentiation in the Dichroplus elongatus species group, we analyzed the karyotypes of four species with classical cytogenetic and mapping several multigene families through fluorescent in situ hybridization (FISH). We improved the taxon sampling of the D. elongatus species group adding new molecular data to infer the phylogeny of the genus and reconstruct the karyotype evolution. Our molecular analyses recovered a fully resolved tree with no evidence for the monophyly of Dichroplus. However, we recovered several stable clades within the genus, including the D. elongatus species group, under the different strategies of tree analyses (Maximum Parsimony and Maximum Likelihood). The chromosomal data revealed minor variation in the D. elongatus species group's karyotypes caused by chromosome rearrangements compared to the phylogenetically related D. maculipennis species group. The karyotypes of D. intermedius and D. exilis described herein showed the standard characteristics found in most Dichroplini, 2n = 23/24, X0♂ XX♀, Fundamental number (FN) = 23/24. However, we noticed two established pericentric inversions in D. intermedius karyotype, raising the FN to 27♂/28♀. A strong variation in the heterochromatic blocks distribution was evidenced at interespecific level. The multigene families' mapping revealed significant variation, mainly in rDNA clusters. These variations are probably caused by micro chromosomal changes, such as movement of transposable elements (TEs) and ectopic recombination. These observations suggest a high genomic dynamism for these repetitive DNA sequences in related species. The reconstruction of the chromosome character "variation in the FN" posits the FN = 23/24 as the ancestral state, and it is hypothesized that variations due to pericentric inversions has arisen independently three times in the evolutionary history of Dichroplus. One of these independent events occurred in the D. elongatus species group, where D. intermedius is the unique case with the highest FN described in the tribe Dichroplini.Centro de Estudios Parasitológicos y de VectoresFacultad de Ciencias Naturales y Muse

Critical Behavior of Dimensionally Continued Black Holes

The critical behavior of black holes in even and odd dimensional spacetimes is studied based on Ba\~nados-Teitelboim-Zanelli (BTZ) dimensionally continued black holes. In even dimensions it is found that asymptotically flat and anti de-Sitter Reissner-Nordstr\"om black holes present up to two second order phase transitions. The case of asymptotically anti-de-Sitter Schwarzschild black holes present only one critical transition and a minimum of temperature, which occurs at the transition. Finally, it is shown that phase transitions are absent in odd dimensions.Comment: 21 pages in Latex format, no figures, vastly improved version to appear in Phys. Rev.

Matter effects on neutrino oscillations in gravitational and magnetic fields

When neutrinos propagate in a background, their gravitational couplings are modified by their weak interactions with the particles in the background. In a medium that contains electrons but no muons or taons, the matter-induced gravitational couplings of neutrinos are different for the various neutrino flavors, and they must be taken into account in describing the phenomena associated with the neutrino oscillations in the presence of strong gravitational fields. Here we incorporate those couplings in that description, including also the effects of a magnetic field, and consider the implications that they have for the emission of high energy neutrinos in the vicinity of Active Galactic Nuclei.Comment: Latex, 12 page

200 años del ingreso de José Gervasio Artigas al Paraguay

This 2020 marks the two hundredth anniversary of the arrival of José Gervasio Artigas to Paraguay, where he lived for thirty years until his death in 1850. For this reason, the cultural supplement of the newspaper ABC Color invited four historians from Uruguay, Argentina and Paraguay to write about the context and circumstances in which this event took place, and to offer observations that shed light on the three decades that Artigas spent in Paraguay, witnessing profound political and social transformations. During the preparation of the texts, the authors engaged in dialogue, exchanged ideas, read each other and became more aware - if possible - of the need to deepen the conversation. Thus, it seemed appropriate to revise and expand the scope of the contributions and then publish them in the format of an authentic round table for dialogue and exchange of information on exile, social life in nineteenth-century Paraguay and the connections of federalism in Uruguay, Paraguay and Argentina.En este 2020 se cumplen doscientos años de la llegada de José Gervasio Artigas alParaguay, país en el que vivió durante treinta años hasta su fallecimiento, en 1850. Por talmotivo, el suplemento cultural del diario ABC Color convocó a cuatro historiadores deUruguay, Argentina y Paraguay para escribir sobre el contexto y las circunstancias en que seprodujo ese hecho, y ofrecer observaciones que permitieran arrojar luz sobre las tres décadasque Artigas pasó en el Paraguay, siendo testigo de profundas transformaciones políticas ysociales. Durante la preparación de los textos los autores dialogamos, intercambiamos ideas,nos leímos y nos hicimos más conscientes –si cabe– sobre la necesidad de profundizar laconversación. De este modo, nos pareció oportuno revisar y ampliar los márgenes de lascontribuciones para luego publicarlas en el formato de una auténtica mesa redonda de diálogoe intercambio de informaciones sobre el exilio, la vida social en el Paraguay decimonónico ylas conexiones del federalismo en Uruguay, Paraguay y Argentina

Phylogeny and chromosomal diversification in the <i>Dichroplus elongatus</i> species group (Orthoptera, Melanoplinae)

In an attempt to track the chromosomal differentiation in the Dichroplus elongatus species group, we analyzed the karyotypes of four species with classical cytogenetic and mapping several multigene families through fluorescent in situ hybridization (FISH). We improved the taxon sampling of the D. elongatus species group adding new molecular data to infer the phylogeny of the genus and reconstruct the karyotype evolution. Our molecular analyses recovered a fully resolved tree with no evidence for the monophyly of Dichroplus. However, we recovered several stable clades within the genus, including the D. elongatus species group, under the different strategies of tree analyses (Maximum Parsimony and Maximum Likelihood). The chromosomal data revealed minor variation in the D. elongatus species group's karyotypes caused by chromosome rearrangements compared to the phylogenetically related D. maculipennis species group. The karyotypes of D. intermedius and D. exilis described herein showed the standard characteristics found in most Dichroplini, 2n = 23/24, X0♂ XX♀, Fundamental number (FN) = 23/24. However, we noticed two established pericentric inversions in D. intermedius karyotype, raising the FN to 27♂/28♀. A strong variation in the heterochromatic blocks distribution was evidenced at interespecific level. The multigene families' mapping revealed significant variation, mainly in rDNA clusters. These variations are probably caused by micro chromosomal changes, such as movement of transposable elements (TEs) and ectopic recombination. These observations suggest a high genomic dynamism for these repetitive DNA sequences in related species. The reconstruction of the chromosome character "variation in the FN" posits the FN = 23/24 as the ancestral state, and it is hypothesized that variations due to pericentric inversions has arisen independently three times in the evolutionary history of Dichroplus. One of these independent events occurred in the D. elongatus species group, where D. intermedius is the unique case with the highest FN described in the tribe Dichroplini.Centro de Estudios Parasitológicos y de Vectore