Time-Reversal Symmetry Breaking and Decoherence in Chaotic Dirac Billiards

In this work, we perform a statistical study on Dirac Billiards in the extreme quantum limit (a single open channel on the leads). Our numerical analysis uses a large ensemble of random matrices and demonstrates the preponderant role of dephasing mechanisms in such chaotic billiards. Physical implementations of these billiards range from quantum dots of graphene to topological insulators structures. We show, in particular, that the role of finite crossover fields between the universal symmetries quickly leaves the conductance to the asymptotic limit of unitary ensembles. Furthermore, we show that the dephasing mechanisms strikingly lead Dirac billiards from the extreme quantum regime to the semiclassical Gaussian regime

A Framework for Efficient Adaptively Secure Composable Oblivious Transfer in the ROM

Oblivious Transfer (OT) is a fundamental cryptographic protocol that finds a number of applications, in particular, as an essential building block for two-party and multi-party computation. We construct a round-optimal (2 rounds) universally composable (UC) protocol for oblivious transfer secure against active adaptive adversaries from any OW-CPA secure public-key encryption scheme with certain properties in the random oracle model (ROM). In terms of computation, our protocol only requires the generation of a public/secret-key pair, two encryption operations and one decryption operation, apart from a few calls to the random oracle. In~terms of communication, our protocol only requires the transfer of one public-key, two ciphertexts, and three binary strings of roughly the same size as the message. Next, we show how to instantiate our construction under the low noise LPN, McEliece, QC-MDPC, LWE, and CDH assumptions. Our instantiations based on the low noise LPN, McEliece, and QC-MDPC assumptions are the first UC-secure OT protocols based on coding assumptions to achieve: 1) adaptive security, 2) optimal round complexity, 3) low communication and computational complexities. Previous results in this setting only achieved static security and used costly cut-and-choose techniques.Our instantiation based on CDH achieves adaptive security at the small cost of communicating only two more group elements as compared to the gap-DH based Simplest OT protocol of Chou and Orlandi (Latincrypt 15), which only achieves static security in the ROM

Dynamical analysis of the cluster pair: A3407 + A3408

We carried out a dynamical study of the galaxy cluster pair A3407 \& A3408 based on a spectroscopic survey obtained with the 4 meter Blanco telescope at the CTIO, plus 6dF data, and ROSAT All-Sky-Survey. The sample consists of 122 member galaxies brighter than $m_R=20$. Our main goal is to probe the galaxy dynamics in this field and verify if the sample constitutes a single galaxy system or corresponds to an ongoing merging process. Statistical tests were applied to clusters members showing that both the composite system A3407 + A3408 as well as each individual cluster have Gaussian velocity distribution. A velocity gradient of $\sim 847\pm 114$ $\rm km\;s^{-1}$ was identified around the principal axis of the projected distribution of galaxies, indicating that the global field may be rotating. Applying the KMM algorithm to the distribution of galaxies we found that the solution with two clusters is better than the single unit solution at the 99\% c.l. This is consistent with the X-ray distribution around this field, which shows no common X-ray halo involving A3407 and A3408. We also estimated virial masses and applied a two-body model to probe the dynamics of the pair. The more likely scenario is that in which the pair is gravitationally bound and probably experiences a collapse phase, with the cluster cores crossing in less than $\sim$1 $h^{-1}$ Gyr, a pre-merger scenario. The complex X-ray morphology, the gas temperature, and some signs of galaxy evolution in A3408 suggests a post-merger scenario, with cores having crossed each other $\sim 1.65 h^{-1}$Gyr ago, as an alternative solution.Comment: 17 pages, 12 figures, submitted to MNRAS, accepted 2016 May 9. Received 2016 May 9; in original form 2016 April 1

The solar, exoplanet and cosmological lithium problems

We review three Li problems. First, the Li problem in the Sun, for which some previous studies have argued that it may be Li-poor compared to other Suns. Second, we discuss the Li problem in planet hosting stars, which are claimed to be Li-poor when compared to field stars. Third, we discuss the cosmological Li problem, i.e. the discrepancy between the Li abundance in metal-poor stars (Spite plateau stars) and the predictions from standard Big Bang Nucleosynthesis. In all three cases we find that the "problems" are naturally explained by non-standard mixing in stars.Comment: Astrophysics and Space Science, in press. New version has one reference correcte

Remote sensing applied to geological mapping; comparative geomorphology and identification of mineral zones of zinc and lead in the region of Vazante, MG

The author has identified the following significant results. Results showed that the black and white aerial photographs and the color infrared transparencies were efficient for mapping of three lithological units of the Paraopeba formation and for mineralized zones identification, respectively. Multispectral transparencies of I2S made it easier to separate dolomites, which were the rocks conditioning zinc and lead mineralization. Statistical analysis of morphometric indexes obtained from black and white photographs and topographic charts showed significant difference among three lithological units of Paraopeba formation which can be defined as Crest, Hilly, and Karstic reliefs

Estratégias ambientais em grandes empresas com atividade galvânica no Rio Grande do Sul.

As pressões sociais sinalizam que os custos para adequação da empresa às demandas do meio ambiente podem se transformar em conscientização, pois a sociedade não mais aceita a exacerbação do lucro obtido às custas dos efeitos ambientais negativos. Assim, a proteção ambiental deixou de ser uma função exclusiva da produção para ser uma função da empresa, fazendo parte da estrutura organizacional e do planejamento estratégico. As empresas que possuem processos galvânicos são consideradas de alto impacto ambiental, devido ao grande consumo de água, energia, geração de emissões e resíduos sólidos perigosos. Conciliar a atividade produtiva com a sustentabilidade ambiental é um desafio enfrentado pelas empresas. Este contexto determinou o problema da pesquisa: qual o tipo e o foco das estratégias ambientais adotadas pelas grandes empresas do Rio Grande do Sul com atividade galvânica para o controle dos impactos negativos? O objetivo do trabalho foi identificar tipos de estratégias implantadas pelas empresas pesquisadas. Para a realização da pesquisa foi usado o método investigativo, a partir do estudo de caso em cinco grandes empresas. O estudo de caso permitiu identificar o potencial das empresas gaúchas para a implantação de estratégias preventivas que possibilitam reduzir perdas e a poluição ambiental

Estratégias ambientais nas grandes empresas do rio grande do sul com processo galvânico.

As pressões sociais sinalizam que os custos para adequação da empresa às demandas do meio ambiente podem se transformar em conscientização, pois a sociedade não mais aceita a exacerbação do lucro obtido às custas dos efeitos ambientais negativos. Assim, a proteção ambiental deixou de ser uma função exclusiva da produção para ser uma função da empresa, fazendo parte da estrutura organizacional e do planejamento estratégico. As empresas que possuem processos galvânicos são consideradas de alto impacto ambiental devido ao grande consumo de água, energia, geração de emissões e resíduos sólidos perigosos. Conciliar a atividade produtiva com a sustentabilidade ambiental é um desafio enfrentado pelas empresas. Este contexto determinou o problema da pesquisa: qual o tipo e o foco das estratégias ambientais adotadas pelas grandes empresas do Rio Grande do Sul com atividade galvânica para o controle dos impactos negativos? O objetivo do trabalho foi identificar tipos de estratégias, a partir das medidas ambientais implantadas nas empresas pesquisadas. Para a realização da pesquisa foi usado o método investigativo, a partir do estudo de caso em cinco grandes empresas. O período realização da pesquisa foi de abril a setembro de 2003. O estudo de caso permitiu identificar o potencial das empresas gaúchas para a implantação de estratégias preventivas que possibilitam reduzir perdas e a poluição ambiental