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Spin-1 duality in $D$-dimensions
D. Dalmazi,R. C. Santos
Physics , 2011, DOI: 10.1103/PhysRevD.84.045027
Abstract: It is known that the Maxwell theory in $D$ dimensions can be written in a first order form (in derivatives) by introducing a totally antisymmetric field which leads to a $(D-3)$-form dual theory. Remarkably, one can replace the antisymmetric field by a symmetric rank two tensor ($W_{\mu\nu}=W_{\nu\mu}$). Such master action establishes the duality between the Maxwell-theory and a fourth order higher rank model in a $D$-dimensional flat space time. A naive generalization to the curved space shows a connection between the recently found D=4 critical gravity and the Maxwell theory plus a coupling term to the Ricci tensor ($R_{\mu\nu}A^{\mu}A^{\nu}$). The mass of the spin-1 particle which appears in the D=4 critical gravity linearized around anti-de Sitter space is the same one obtained from the Ricci coupling term. We also work out, in flat space time, the explicitly massive case (Maxwell-Proca) which is dual to a second order theory for $W_{\mu\nu}$.
Comment on "Constraining the smoothness parameter and dark energy using observational H(z) data"
V. C. Busti,R. C. Santos
Physics , 2011, DOI: 10.1088/1674-4527/11/6/003
Abstract: In this Comment we discuss a recent analysis by Yu et al. [RAA 11, 125 (2011)] about constraints on the smoothness $\alpha$ parameter and dark energy models using observational $H(z)$ data. It is argued here that their procedure is conceptually inconsistent with the basic assumptions underlying the adopted Dyer-Roeder approach. In order to properly quantify the influence of the $H(z)$ data on the smoothness $\alpha$ parameter, a $\chi^2$-test involving a sample of SNe Ia and $H(z)$ data in the context of a flat $\Lambda$CDM model is reanalyzed. This result is confronted with an earlier approach discussed by Santos et al. (2008) without $H(z)$ data. In the ($\Omega_m, \alpha$) plane, it is found that such parameters are now restricted on the intervals $0.66 \leq \alpha \leq 1.0$ and $0.27 \leq \Omega_m \leq 0.37$ within 95.4% confidence level (2$\sigma$), and, therefore, fully compatible with the homogeneous case. The basic conclusion is that a joint analysis involving $H(z)$ data can indirectly improve our knowledge about the influence of the inhomogeneities. However, this happens only because the $H(z)$ data provide tighter constraints on the matter density parameter $\Omega_m$.
Hamilton-Jacobi approach for power-law potentials
Santos, R. C.;Santos, J.;Lima, J. A. S.;
Brazilian Journal of Physics , 2006, DOI: 10.1590/S0103-97332006000700024
Abstract: the classical and relativistic hamilton-jacobi approach is applied to the one-dimensional homogeneous potential, v(q) = aqn, where a and n are continuously varying parameters. in the non-relativistic case, the exact analytical solution is determined in terms of a, n and the total energy e. it is also shown that the non-linear equation of motion can be linearized by constructing a hypergeometric differential equation for the inverse problem t(q). a variable transformation reducing the general problem to that one of a particle subjected to a linear force is also established. for any value of n, it leads to a simple harmonic oscillator if e > 0, an "anti-oscillator" if e < 0, or a free particle if e = 0. however, such a reduction is not possible in the relativistic case. for a bounded relativistic motion, the first order correction to the period is determined for any value of n. for n >> 1, it is found that the correction is just twice that one deduced for the simple harmonic oscillator (n = 2), and does not depend on the specific value of n.
Hamilton-Jacobi Approach for Power-Law Potentials
R. C. Santos,J. Santos,J. A. S. Lima
Physics , 2006, DOI: 10.1590/S0103-97332006000700024
Abstract: The classical and relativistic Hamilton-Jacobi approach is applied to the one-dimensional homogeneous potential, $V(q)=\alpha q^n$, where $\alpha$ and $n$ are continuously varying parameters. In the non-relativistic case, the exact analytical solution is determined in terms of $\alpha$, $n$ and the total energy $E$. It is also shown that the non-linear equation of motion can be linearized by constructing a hypergeometric differential equation for the inverse problem $t(q)$. A variable transformation reducing the general problem to that one of a particle subjected to a linear force is also established. For any value of $n$, it leads to a simple harmonic oscillator if $E>0$, an "anti-oscillator" if $E<0$, or a free particle if E=0. However, such a reduction is not possible in the relativistic case. For a bounded relativistic motion, the first order correction to the period is determined for any value of $n$. For $n >> 1$, it is found that the correction is just twice that one deduced for the simple harmonic oscillator ($n=2$), and does not depend on the specific value of $n$.
Projeto, constru??o e teste de um Torcímetro
Santos, D.C.;Barbieri, R.;
Matéria (Rio de Janeiro) , 2011, DOI: 10.1590/S1517-70762011000200006
Abstract: the torsiometer is a device used to measure the change in angle between two positions and one of its applications is to measure the angle of twist in torsion tests of materials. this paper describes the working principle, the main details of design and construction of a low cost torsiometer. its calibration curve and some experimental results are also shown to quantify the measurements obtained with this prototype.
Natural inflation in 5D warped backgrounds
Felipe, R. Gonzalez;Santos, N. M. C.
High Energy Physics - Phenomenology , 2007, DOI: 10.1103/PhysRevD.78.023519
Abstract: In light of the five-year data from the Wilkinson Microwave Anisotropy Probe (WMAP), we discuss models of inflation based on the pseudo Nambu-Goldstone potential predicted in five-dimensional gauge theories for different backgrounds: flat Minkowski, anti-de Sitter, and dilatonic spacetime. In this framework, the inflaton potential is naturally flat due to shift symmetries and the mass scales associated with it are related to 5D geometrical quantities.
LIVE BAIT DEMAND OF THE TUNA FISHERY FLEET FROM SANTA CATARINA STATE (BRAZIL), ON THE 1998/99 HARVEST: CPUE, COMPOSITION AND DISTRIBUTION CATCH. DEMANDA DE ISCAS VIVAS PARA A FROTA ATUNEIRA CATARINENSE NA SAFRA DE 1998/99: CPUE, COMPOSI O E DISTRIBUI O DAS CAPTURAS
R. C. SANTOS,M. RODRIGUES-RIBEIRO
Brazilian Journal of Aquatic Science and Technology , 2000,
Abstract: Tuna fishery by pole and line or baitboat was developed many years ago by Japanese fisherman. And latter incorporated by Portuguese and Spanish among others. The method consists of fishing with pole and line on tuna schools that are attracted and kept to the boat with the aid of constant thrown of live bait in the sea. This technique was firstly introduced in Brazil the seventies and nowadays is one of the most lucrative fisheries of Brazil. The main objective of this work was to identify the species which are used as live baits in this kind of fishery their main areas of capture, as well as to estimate the CPUE of the industrial fleet , on the bait stock, during the harvest period of 1998/99. Results showed that seven species of Clupeidae and Engraulidae families are used as bait, being Sardinella brasiliensis the most important specie, representing 49% in weight of total caught. Most of the biomass was captured within well delimited intervals of temperature (25°C to 28°C) and depth (5 to 15m), on the Porto Belo region. CPUEs ranged between 261,15 e 1654,3 Kg /day of bait fishing. A captura de atuns e afins pelo método de vara e isca viva foi desenvolvida e é utilizada há séculos por pescadores japoneses, posteriormente adotada por a orianos e espanhóis, entre outros. A técnica consiste em pescar com vara, linha e anzol sobre cardumes que s o atraídos e mantidos próximos à embarca o pelo fornecimento periódico de iscas vivas. Esta modalidade de pesca foi introduzida no Brasil ao final da década de 70 e hoje se destaca como uma das mais rentáveis do País. O objetivo geral deste trabalho foi identificar as espécies utilizadas como isca viva nesta pescaria, suas principais áreas de captura, bem como as CPUEs empregadas pela frota sobre a isca, durante a safra de 1998/99. Durante esse período foram utilizadas como isca sete espécies pertencentes às famílias Clupeidae e Engraulidae, sendo a sardinha-verdadeira (Sardinella brasiliensis) a mais importante, representando 49%. A maior parte da biomassa foi capturada em intervalos de temperatura (25 a 28°C) e profundidade (5 a 15 metros) bem determinados, na regi o de Porto Belo. As CPUEs (captura por unidade de esfor o) variaram entre 261,15 e 1654,3 Kg/dia de iscagem.
Performance of Single and Concatenated Sets of Mitochondrial Genes at Inferring Metazoan Relationships Relative to Full Mitogenome Data
Justin C. Havird, Scott R. Santos
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0084080
Abstract: Mitochondrial (mt) genes are some of the most popular and widely-utilized genetic loci in phylogenetic studies of metazoan taxa. However, their linked nature has raised questions on whether using the entire mitogenome for phylogenetics is overkill (at best) or pseudoreplication (at worst). Moreover, no studies have addressed the comparative phylogenetic utility of mitochondrial genes across individual lineages within the entire Metazoa. To comment on the phylogenetic utility of individual mt genes as well as concatenated subsets of genes, we analyzed mitogenomic data from 1865 metazoan taxa in 372 separate lineages spanning genera to subphyla. Specifically, phylogenies inferred from these datasets were statistically compared to ones generated from all 13 mt protein-coding (PC) genes (i.e., the “supergene” set) to determine which single genes performed “best” at, and the minimum number of genes required to, recover the “supergene” topology. Surprisingly, the popular marker COX1 performed poorest, while ND5, ND4, and ND2 were most likely to reproduce the “supergene” topology. Averaged across all lineages, the longest ~2 mt PC genes were sufficient to recreate the “supergene” topology, although this average increased to ~5 genes for datasets with 40 or more taxa. Furthermore, concatenation of the three “best” performing mt PC genes outperformed that of the three longest mt PC genes (i.e, ND5, COX1, and ND4). Taken together, while not all mt PC genes are equally interchangeable in phylogenetic studies of the metazoans, some subset can serve as a proxy for the 13 mt PC genes. However, the exact number and identity of these genes is specific to the lineage in question and cannot be applied indiscriminately across the Metazoa.
Trading Places—Switching Frataxin Function by a Single Amino Acid Substitution within the [Fe-S] Cluster Assembly Scaffold
Dennis R. Dean?,Patricia C. Dos Santos
PLOS Genetics , 2015, DOI: 10.1371/journal.pgen.1005192
Abstract:
Clustering, Angular Size and Dark Energy
R. C. Santos,J. A. S. Lima
Physics , 2008, DOI: 10.1103/PhysRevD.77.083505
Abstract: The influence of dark matter inhomogeneities on the angular size-redshift test is investigated for a large class of flat cosmological models driven by dark energy plus a cold dark matter component (XCDM model). The results are presented in two steps. First, the mass inhomogeneities are modeled by a generalized Zeldovich-Kantowski-Dyer-Roeder (ZKDR) distance which is characterized by a smoothness parameter $\alpha(z)$ and a power index $\gamma$, and, second, we provide a statistical analysis to angular size data for a large sample of milliarcsecond compact radio sources. As a general result, we have found that the $\alpha$ parameter is totally unconstrained by this sample of angular diameter data.
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