Multiply subtractive generalized Kramers-Kronig relations: application on third harmonic generation susceptibility on polysilane

We present multiply subtractive Kramers-Kronig (MSKK) relations for the moments of arbitrary order harmonic generation susceptibility. Using experimental data on third-harmonic wave from polysilane, we show that singly subtractive Kramers-Kronig (SSKK) relations provide better accuracy of data inversion than the conventional Kramers-Kronig (K-K) relations. The fundamental reason is that SSKK and MSKK relations have strictly faster asymptotic decreasing integrands than the conventional K-K relations. Therefore SSKK and MSKK relations can provide a reliable optical data inversion procedure based on the use of measured data only.Comment: 14 pages, 2 figure

Submillimeter Spectrum of Formic Acid

We have measured new submillimeter-wave data around 600 GHz and around 1.1 THz for the 13C isotopologue of formic acid and for the two deuterium isotopomers; in each case for both the trans and cis rotamer. For cis-DCOOH and cis-HCOOD in particular only data up to 50 GHz was previously available. For all species the quality and quantity of molecular parameters has been increased providing new measured frequencies and more precise and reliable frequencies in the range of existing and near-future submillimeter and far-infrared astronomical spectroscopy instruments such as Herschel, SOFIA and ALMA

Negative energy and stability in scalar-tensor gravity

Linearized gravitational waves in Brans-Dicke and scalar-tensor theories carry negative energy. A gauge-invariant analysis shows that the background Minkowski space is stable at the classical level with respect to linear scalar and tensor inhomogeneous perturbations.Comment: 9 pages, latex, to appear in Phys. Rev.

Mechanisms of femtosecond laser-induced refractive index modification of poly(methyl methacrylate)

The mechanisms of refractive index change in poly(methyl methacrylate) by frequency doubled femtosecond laser pulses are investigated. It is demonstrated that positive refractive index modificaton can be caused by a combination of depolymerization and crosslinking

Cigarrinha-das-Pastagens : uma praga que retorna com as chuvas.

bitstream/item/139024/1/cnpgc-divulga-08.pdfCNPGC. Serie nao convencional

Haematobia irritans L: um novo problema para a bovinocultura no Brasil.

bitstream/item/138551/1/COT-25.pdfCNPGC

Cosmological implications of an evolutionary quantum gravity

The cosmological implications of an evolutionary quantum gravity are analyzed in the context of a generic inhomogeneous model. The Schr\"{o}dinger problem is formulated and solved in the presence of a scalar field, an ultrarelativistic matter and a perfect gas regarded as the dust-clock. Considering the actual phenomenology, it is shown how the evolutionary approach overlaps the Wheeler-DeWitt one.Comment: 4 pages; to appear in the proceedings of the II Stueckelberg Workshop, Int.J.Mod.Phys.A, references adde

Null test for interactions in the dark sector

Since there is no known symmetry in Nature that prevents a non-minimal coupling between the dark energy (DE) and cold dark matter (CDM) components, such a possibility constitutes an alternative to standard cosmology, with its theoretical and observational consequences being of great interest. In this paper we propose a new null test on the standard evolution of the dark sector based on the time dependence of the ratio between the CDM and DE energy densities which, in the standard $\Lambda$CDM scenario, scales necessarily as $a^{-3}$. We use the latest measurements of type Ia supernovae, cosmic chronometers and angular baryonic acoustic oscillations to reconstruct the expansion history using model-independent Machine Learning techniques, namely, the Linear Model formalism and Gaussian Processes. We find that while the standard evolution is consistent with the data at $3\sigma$ level, some deviations from the $\Lambda$CDM model are found at low redshifts, which may be associated with the current tension between local and global determinations of $H_0$.Comment: 15 pages, 12 figure

Accurate Modeling of Weak Lensing with the sGL Method

We revise and extend the stochastic approach to cumulative weak lensing (hereafter the sGL method) first introduced in Ref. [1]. Here we include a realistic halo mass function and density profiles to model the distribution of mass between and within galaxies, galaxy groups and galaxy clusters. We also introduce a modeling of the filamentary large-scale structures and a method to embed halos into these structures. We show that the sGL method naturally reproduces the weak lensing results for the Millennium Simulation. The strength of the sGL method is that a numerical code based on it can compute the lensing probability distribution function for a given inhomogeneous model universe in a few seconds. This makes it a useful tool to study how lensing depends on cosmological parameters and its impact on observations. The method can also be used to simulate the effect of a wide array of systematic biases on the observable PDF. As an example we show how simple selection effects may reduce the variance of observed PDF, which could possibly mask opposite effects from very large scale structures. We also show how a JDEM-like survey could constrain the lensing PDF relative to a given cosmological model. The updated turboGL code is available at turboGL.org.Comment: PRD style: 20 pages, 10 figures; replaced to match the improved version accepted for publication in PRD. The updated turboGL code can be downloaded at http://www.turbogl.org