A Note on Tachyon Moduli and Closed Strings

The collective behavior of the SL(2,R) covariant brane states of non-critical c=1 string theory found in a previous work, is studied in the Fermi liquid approximation. It is found that such states mimick the coset WZW model, whereas only by further restrictions one recovers the double-scaling limit which was purported to be equivalent to closed string models. Another limit is proposed, inspired by the tachyon condensation ideas, where the spectrum is the same of two-dimensional string theory. We close by noting some strange connections between vacuum states of the theory in their different interpretations.Comment: PDFLaTeX, 17 pages, 2 figures; Section 2 rewritten, several fixes throughout the text to improve clarit

Constrained Minimization Under Vector-Valued Criteria in Linear Topological Spaces

Constrained minimization under vector valued criteria in linear topological space

Impact of stellar companions on precise radial velocities

Context: With the announced arrival of instruments such as ESPRESSO one can expect that several systematic noise sources on the measurement of precise radial velocity will become the limiting factor instead of photon noise. A stellar companion within the fiber is such a possible noise source. Aims: With this work we aim at characterizing the impact of a stellar companion within the fiber to radial velocity measurements made by fiber-fed spectrographs. We consider the contaminant star either to be part of a binary system whose primary star is the target star, or as a background/foreground star. Methods: To carry out our study, we used HARPS spectra, co-added the target with contaminant spectra, and then compared the resulting radial velocity with that obtained from the original target spectrum. We repeated this procedure and used different tunable knobs to reproduce the previously mentioned scenarios. Results: We find that the impact on the radial velocity calculation is a function of the difference between individual radial velocities, of the difference between target and contaminant magnitude, and also of their spectral types. For the worst-case scenario in which both target and contaminant star are well centered on the fiber, the maximum contamination for a G or K star may be higher than 10 cm/s, on average, if the difference between target and contaminant magnitude is $\Delta m$ < 10, and higher than 1 m/s if $\Delta m$ < 8. If the target star is of spectral type M, $\Delta m$ < 8 produces the same contamination of 10 cm/s, and a contamination may be higher than 1 m/sComment: Accepted for publication in A&A on 29/12/2019 - 14 page

Asteroseismic Theory of Rapidly Oscillating Ap Stars

This paper reviews some of the important advances made over the last decade concerning theory of roAp stars.Comment: 9 pages, 5 figure

Caracterização dos solos de São José do Norte, Tavares e Mostardas-RS.

bitstream/item/41366/1/Sao-Jose-do-Norte.pdf; bitstream/item/41367/1/mapa-mostarda-capacidade-de-uso.pdf; bitstream/item/41368/1/mapa-mostarda-geomorfologia-e-solos.pdf; bitstream/item/41369/1/mapa-mostarda-solos.pdf; bitstream/item/41370/1/mapa-santa-vitoria-do-palmar-capacidade-de-uso.pdf; bitstream/item/41371/1/mapa-santa-vitoria-do-palmar-geomorfologia.pdf; bitstream/item/41372/1/mapa-santa-vitoria-do-palmar-solos.pdf; bitstream/item/41373/1/mapa-sao-jose-capacidade-de-uso.pdf; bitstream/item/41374/1/mapa-sao-jose-do-Norte.pdf; bitstream/item/41375/1/mapa-sao-jose-geomorfologia-e-solos.pdf; bitstream/item/41376/1/mapa-sao-jose-solos.pdf; bitstream/item/41377/1/mapa-Tavares-capacidade-de-uso-de-terras.pdf; bitstream/item/41378/1/mapa-Tavares-geomorfologia-e-solos.pdf; bitstream/item/41379/1/mapa-Tavares-solos.pd

Considerações sobre os solos da sub-região da Nhecolândia, Pantanal Mato-Grossense.

A Nhecolandia e uma das sub-regioes que compoem o Pantanal Mato Grossense. E totalmente constituida por sedimentos arenosos finos (95%), em deposicao pelo rio Taquari, desde o inicio do Periodo Quaternario, formando um leque aluvial. A sua superficie irregular, composta por um mesorelevo movimentado, conserva ainda a sua configuracao tipicamente aluvial, onde os cordoes arenosos (diques marginais), com cobertura vegetal de cerrado, leitos fosseis obstruidos (campos limpos e vazantes), com vegetacao de gramineas e pequenas lagoas (baias) sao uma sucessao constante. Os podzois hidromorficos -spodic psammaquent e aeric entic sideraquod - constituem os solos mais pobres e suscetiveis a lixiviacao, principalmente se quebrado o equilibrio atual com o uso. Nas bordas da planicie, para onde converge o fluxo freatico, os solos sao ferteis. Sao podzois hidromorficos eutroficos, areias quartzosas eutroficas e solonetz - aquic arenic eutrochrept. Discutem-se aspectos do uso dos solos nas partes nao alagaveis (cordoes arenosos) e a possibilidade de sua perda de fertilidade, com base em dados analiticos que evidenciam perdas de fosforo para as camadas inferiores do solo. Sao questionados alguns parametros em uso na classificacao dos solos no Pais e a sua aplicabilidade aos solos do Pantanal Mato-Grossense