Near-infrared Kerr nonlinearity of Pb(PO3)2–WO3 glasses

We report measurements of the nonlinear refractive index, n 2 , and the nonlinear absorption coefficient, α 2 , of Pb ( PO 3 ) 2 – WO 3 glasses. The measurements were performed using 100 fs (17 ps) laser pulses at 800 nm (1064 nm). Positive values of n 2 ∼ 10 − 19 m 2 / W and negligible α 2 were measured. The results show that the nonlinearity is faster than 100 fs and it is observed an increase of n 2 with the increasing of the WO 3 amount in the samples. The Boling, Glass, and Owyoung model, based on the semiclassical harmonic oscillator model, was used to predict the values of n 2 , with basis on the values of the linear refractive index of the samples

Pragas da soja no Brasil e seu manejo integrado.

Pragas da soja; Pragas que atacam as folhas: Anticarsia gemmatalis (Lep.: Noctuidae); Pseudoplusia includens (Lep.: Noctuidae); Coleopteros desfolhadores; Outros organismos que atacam as folhas; Pragas que atacam vagens e graos: Percevejos sugadores de sementes; Lagartas das vagens; Brocas das vagens; Pragas que atacam plantulas, hastes e peciolos: Sternechus subsignatus (Col.: Curculionidae); Elasmopalpus lignosellus (Lep.: Pyralidae); Epinotia aporema (Lep.: Tortricidae); Outros insetos que atacam plantulas, hastes e peciolos; Pragas que atacam as raizes da soja: Coros; Percevejos-castanho-da-raiz; Outros insetos que atacam as raizes; Inimigos naturais das pragas da soja; Predadores: Hemipteros; Coleopteros; Parasitoides: Parasitoides de lagartas; Parasitoides de percevejos; Entomopatogenos: Virus; Fungos; Amostragem das pragas; Controle integrado e nivel de acao; Controle integrado das pragas que atacam as folhas: Anticarsia gemmatalis; Pseudoplusia includens e outros Plusiinae;; Coleopteros desfolhadores; Outros organismos que atacam as folhas; Controle integrado das pragas que atacam as vagens e graos: Percevejos; Lagarta-das-vagens; Broca-das-vagens; Controle integrado das pragas que atacam plantulas, hastes e peciolos: Sternechus subsignatus; Epinotia aporema; Controle integrado das pragas que atacam as raizes: Coros; Percevejo-castanho-da-raiz.bitstream/item/128003/1/ID-6173.pd

Near-infrared nonlinearity of a multicomponent tellurium oxide glass at 800 and 1,064 nm

We report on the nonlinear (NL) optical properties of glassy TeO2–GeO2–K2O–Bi2O3 at λ = 800 nm and λ = 1,064 nm. Using the Kerr gate technique with a laser delivering 150 fs pulses at 800 nm, we demonstrated the fast NL response of the samples. The modulus of the NL refractive index, n 2, at 800 nm was ~10−15 cm2/W. The Z-scan technique was used to determine n 2 ≈ +10−15 cm2/W, at 1,064 nm with pulses of 17 ps. The two-photon absorption coefficient, α 2, was smaller than the minimum that we can measure (<0.003 cm/GW). The figure of merit n 2/α 2 λ was calculated and indicates that this glass composition has large potential to be used for all-optical switching

Calculating invariants as coreflexive bisimulations

Invariants, bisimulations and assertions are the main ingredients of coalgebra theory applied to software systems. In this paper we reduce the first to a particular case of the second and show how both together pave the way to a theory of coalgebras which regards invariant predicates as types. An outcome of such a theory is a calculus of invariants’ proof obligation discharge, a fragment of which is presented in the paper. The approach has two main ingredients: one is that of adopting relations as “first class citizens” in a pointfree reasoning style; the other lies on a synergy found between a relational construct, Reynolds’ relation on functions involved in the abstraction theorem on parametric polymorphism and the coalgebraic account of bisimulations and invariants. This leads to an elegant proof of the equivalence between two different definitions of bisimulation found in coalgebra literature (due to B. Jacobs and Aczel & Mendler, respectively) and to their instantiation to the classical Park-Milner definition popular in process algebra.Partially supported by the Fundacao para a Ciencia e a Tecnologia, Portugal, under grant number SFRH/BD/27482/2006

Measuring CMB Polarization with BOOMERANG

BOOMERANG is a balloon-borne telescope designed for long duration (LDB) flights around Antarctica. The second LDB Flight of BOOMERANG took place in January 2003. The primary goal of this flight was to measure the polarization of the CMB. The receiver uses polarization sensitive bolometers at 145 GHz. Polarizing grids provide polarization sensitivity at 245 and 345 GHz. We describe the BOOMERANG telescope noting changes made for 2003 LDB flight, and discuss some of the issues involved in the measurement of polarization with bolometers. Lastly, we report on the 2003 flight and provide an estimate of the expected results.Comment: 12 pages, 8 figures, To be published in the proceedings of "The Cosmic Microwave Background and its Polarization", New Astronomy Reviews, (eds. S. Hanany and K.A. Olive). Fixed typos, and reformatted citation

Double Inflation in Supergravity and the Large Scale Structure

The cosmological implication of a double inflation model with hybrid + new inflations in supergravity is studied. The hybrid inflation drives an inflaton for new inflation close to the origin through supergravity effects and new inflation naturally occurs. If the total e-fold number of new inflation is smaller than $\sim 60$, both inflations produce cosmologically relevant density fluctuations. Both cluster abundances and galaxy distributions provide strong constraints on the parameters in the double inflation model assuming $\Omega_0=1$ standard cold dark matter scenario. The future satellite experiments to measure the angular power spectrum of the cosmic microwave background will make a precise determination of the model parameters possible.Comment: 19 pages (RevTeX file

Some anisotropic universes in the presence of imperfect fluid coupling with spatial curvature

We consider Bianchi VI spacetime, which also can be reduced to Bianchi types VI0-V-III-I. We initially consider the most general form of the energy-momentum tensor which yields anisotropic stress and heat flow. We then derive an energy-momentum tensor that couples with the spatial curvature in a way so as to cancel out the terms that arise due to the spatial curvature in the evolution equations of the Einstein field equations. We obtain exact solutions for the universes indefinetly expanding with constant mean deceleration parameter. The solutions are beriefly discussed for each Bianchi type. The dynamics of the models and fluid are examined briefly, and the models that can approach to isotropy are determined. We conclude that even if the observed universe is almost isotropic, this does not necessarily imply the isotropy of the fluid (e.g., dark energy) affecting the evolution of the universe within the context of general relativity.Comment: 17 pages, no figures; to appear in International Journal of Theoretical Physics; in this version (which is more concise) an equation added, some references updated and adde

Transforming data by calculation

Thispaperaddressesthefoundationsofdata-modeltransformation.A catalog of data mappings is presented which includes abstraction and representa- tion relations and associated constraints. These are justified in an algebraic style via the pointfree-transform, a technique whereby predicates are lifted to binary relation terms (of the algebra of programming) in a two-level style encompassing both data and operations. This approach to data calculation, which also includes transformation of recursive data models into “flat” database schemes, is offered as alternative to standard database design from abstract models. The calculus is also used to establish a link between the proposed transformational style and bidi- rectional lenses developed in the context of the classical view-update problem.Fundação para a Ciência e a Tecnologia (FCT

Simulating Cosmic Microwave Background maps in multi-connected spaces

This article describes the computation of cosmic microwave background anisotropies in a universe with multi-connected spatial sections and focuses on the implementation of the topology in standard CMB computer codes. The key ingredient is the computation of the eigenmodes of the Laplacian with boundary conditions compatible with multi-connected space topology. The correlators of the coefficients of the decomposition of the temperature fluctuation in spherical harmonics are computed and examples are given for spatially flat spaces and one family of spherical spaces, namely the lens spaces. Under the hypothesis of Gaussian initial conditions, these correlators encode all the topological information of the CMB and suffice to simulate CMB maps.Comment: 33 pages, 55 figures, submitted to PRD. Higher resolution figures available on deman