Decoherence, pointer engineering and quantum state protection

We present a proposal for protecting states against decoherence, based on the engineering of pointer states. We apply this procedure to the vibrational motion of a trapped ion, and show how to protect qubits, squeezed states, approximate phase eigenstates and superpositions of coherent states.Comment: 1 figur

Silagem de leucena em tambores: tecnologia para pequenos produtores.

bitstream/item/68474/1/Silagem0001.pd

Third-order nonlinear optical properties of bismuth-borate glasses measured by conventional and thermally managed eclipse Z scan

Third-order nonlinearity one order of magnitude larger than silica is measured in bismuth-borate glasses presenting a fast response (<200 fs). The results for the sign and magnitude of the nonlinearity were obtained using a combination of the eclipse Z scan with thermal nonlinearity managed Z scan, whereas the Kerr shutter technique was employed to obtain the electronic time response of the nonlinearity, all performed with 76 MHz repetition rate 150 fs pulses at 800 nm. Conventional Z scans in the picosecond regime at 532 and 1064 nm were also independently performed, yielding the values of the third-order nonlinear susceptibilities at those wavelengths. The results obtained for the femtosecond response, enhanced third-order nonlinearity of this glass (with respect to silica), place this glass system as an important tool in the development of photonics devices. Electro-optical modulators, optical switches, and frequency converters are some of the applications using second-order nonlinear properties of the Bi-glass based on the rectification model

Reconhecimento e manejo das principais pragas da cenoura.

Este comunicado visa descrever as principais espécies de insetos-praga encontradas no cultivo de cenoura eformas adequadas de manejá-las.bitstream/item/72187/1/cot-821.pd

Education Performance: Was It All Determined 100 Years Ago? Evidence From São Paulo, Brazil

This paper deals with institutional persistence in long-term economic development. We investigate the historical record of education in one of the fastest growing and most unequal societies in the twentieth century – the state of São Paulo, Brazil. Based on historical data from an agricultural census and education statistics, we assess the role played by factors such as land concentration, immigration and type of economic activity in determining supply and demand of education during the early twentieth century, and to what degree these factors help explain current educational performance and income levels. We find a positive and enduring effect of the presence of foreign-born immigrants on the supply of public instruction, as well as a negative effect of land concentration. Immigrant farm-laborers established their own community schools, and pressured for public funding for those schools or for public schools. The effects of early adoption of public instruction can be detected more than one hundred years later in the form of better test scores and higher income per capita. These results are suggestive of an additional mechanism generating inequality across regions: the places that received immigration from countries with an established public education system benefited from an earlier adoption of the revolutionary idea of public education

Education Performance: Was It All Determined 100 Years Ago? Evidence From São Paulo, Brazil

This paper deals with institutional persistence in long-term economic development. We investigate the historical record of education in one of the fastest growing and most unequal societies in the twentieth century – the state of São Paulo, Brazil. Based on historical data from an agricultural census and education statistics, we assess the role played by factors such as land concentration, immigration and type of economic activity in determining supply and demand of education during the early twentieth century, and to what degree these factors help explain current educational performance and income levels. We find a positive and enduring effect of the presence of foreign-born immigrants on the supply of public instruction, as well as a negative effect of land concentration. Immigrant farm-laborers established their own community schools, and pressured for public funding for those schools or for public schools. The effects of early adoption of public instruction can be detected more than one hundred years later in the form of better test scores and higher income per capita. These results are suggestive of an additional mechanism generating inequality across regions: the places that received immigration from countries with an established public education system benefited from an earlier adoption of the revolutionary idea of public education

Time-dependent quantum scattering in 2+1 dimensional gravity

The propagation of a localized wave packet in the conical space-time created by a pointlike massive source in 2+1 dimensional gravity is analyzed. The scattering amplitude is determined and shown to be finite along the classical scattering directions due to interference between the scattered and the transmitted wave functions. The analogy with diffraction theory is emphasized.Comment: 15 pages in LaTeX with 3 PostScript figure

A simple model of rumen cannula

Neste trabalho é descrito e ilustrado um modelo adaptado de cânula ruminal para bovinos, ovinos e caprinos, que pode ser confeccionado com material facilmente encontrado no comércio, a baixo custo. Consiste de adaptadores de PVC para caixas d'água e acessórios (flanges, luvas e tampas), nos quais são feitas algumas modificações. A utilização desse tipo de cânula em bovinos e ovinos não tem causado problemas de adaptação.This paper describes, with illustrations a modal of rumen cannula adapted for cattle, sheep and goats. It may be made from inexpensive material available in a neighborhood store: water box adapters, flanges, gloves and caps, in which some modifications have been made. The utilization of this type of cannula in cattle and sheep has caused no adaptation problems