Image formation by manipulation of the entangled angular spectrum

We demonstrate theoretical and experimentally how it is possible to manipulate an entangled angular spectrum of twin beams, in order to reconstruct correlated images with coincidence detection. The entangled angular spectrum comes from the pump and the image is obtained only if signal and idler are properly treated.Comment: Submitted for publication in Optics Communication

Spatial antibunching of photons with parametric down-conversion

The theoretical framework behind a recent experiment by Nogueira et. al. [Phys. Rev. Lett. 86}, 4009 (2001)] of spatial antibunching in a two-photon state generated by collinear type II parametric down-conversion and a birefringent double-slit is presented. The fourth-order quantum correlation function is evaluated and shown to violate the classical Schwarz-type inequality, ensuring that the field does not have a classical analog. We expect these results to be useful in the rapidly growing fields of quantum imaging and quantum information.Comment: 5 pages, 3 figures. Minor changes made, accepted for publication in PR

Critical end point behaviour in a binary fluid mixture

We consider the liquid-gas phase boundary in a binary fluid mixture near its critical end point. Using general scaling arguments we show that the diameter of the liquid-gas coexistence curve exhibits singular behaviour as the critical end point is approached. This prediction is tested by means of extensive Monte-Carlo simulations of a symmetrical Lennard-Jones binary mixture within the grand canonical ensemble. The simulation results show clear evidence for the proposed singularity, as well as confirming a previously predicted singularity in the coexistence chemical potential [Fisher and Upton, Phys. Rev. Lett. 65, 2402 (1990)]. The results suggest that the observed singularities, particularly that in the coexistence diameter, should also be detectable experimentally.Comment: 17 pages Revtex, 11 epsf figures. To appear in Phys. Rev.

Efeito do genótipo e da idade de ovinos na reatividade medida em pista de venda

Objetivou-se avaliar o comportamento de ovinos e relacionar aspectos comportamentais com a raça e idade dos animais. Foram observados 5.971 animais divididos em 181 lotes quanto às raças – Corriedale (n = 2.731), Ideal (n = 1.574), Merino (n = 168), Texel (n = 717), Suffolk (n = 247) e 6 mestiços (n = 534) – e quanto à idade – cordeiras (1,5 ano, n = 3.021), ovelhas (acima de 1,5 ano, n = 2457) e cordeiras dente-de-leite (média de 6 meses de idade, n = 493). O comportamento médio dos lotes foi avaliado pela atribuição de escores de movimentação e resistência à condução na entrada, permanência e saída da pista de comercialização. Os animais das raças mais especializadas para produção de carne (Suffolk e Texel) e os animais jovens foram os mais agitados e apresentaram maior resistência à condução pelo homem em comparação àqueles das raças produtoras de lã e aos mais velhos. Os escores comportamentais foram positivamente relacionados entre si, o que permite a escolha de qualquer um deles para medir o comportamento dos ovinos. O comportamento de ovinos em pista de venda é influenciado pela idade e raça.The objective of this work was to evaluate behavior of sheep and to relate behavioral aspects with breed and age of animals. It was observed 5,971 animals distributed in 181 plots regarded to: breed - Corriedale (n=2,731), Ideal (n=1,574), Merino (n=168), Texel (n=717), Suffolk (n=247) and six crossbreds (n=534); age - yearlings (1.5 year, n=3,021), ewes (above 1.5 year, n =2,457) and lambs (average 6 months of age, n=493). Average behavior of plots was evaluated by attributing scores of movement and resistance to conduction at entrance, permanence and exit from the market auction. Animals from more specialized breeds for meat production (Sulfock and Texel) and young animals were the most agitated and they showed more resistance to human conduction compared to those wool producer breeds and to the older ones. Behavior scores positively correlated among each other, allowing to choose any of them to measure sheep behavior. Sheep on market auction behavior is influenced by age and breed

Retardadores de crescimento no desenvolvimento e na qualidade ornamental de Zinnia elegans Jacq. 'Lilliput' envasada

As zínias têm grande potencial como plantas floríferas envasadas e representam rápida fonte de novidade para a floricultura com o auxílio de retardadores de crescimento. Avaliaram-se os efeitos de retardadores de crescimento no desenvolvimento e na produção de plantas envasadas de porte baixo, compactas e atrativas de 'Lilliput' Zinnia elegans, cultivar altamente ornamental, com sementes de baixo custo. O delineamento experimental foi em blocos casualizados, com dez tratamentos (controle e três concentrações de cada retardador: daminozide, paclobutrazol e chlormequat) e quatro repetições (dois vasos por unidade experimental, com uma planta por vaso de 0,6 L). Paclobutrazol (0,5; 0,75 e 1,0 mg i.a. por vaso) e chlormequat (1,0; 2,0 e 3,0 g L-1) foram aplicados ao substrato (40 mL por vaso), enquanto o daminozide (2,5; 3,75 e 5,0 g L-1) foi aplicado através de pulverização foliar (10 mL por vaso), no estádio de gema floral apical visível. Daminozide (2,5 e 3,75 g L-1), paclobutrazol (0,5; 0,75 e 1,0 mg i.a. por vaso) e 1,0 g L-1 de chlormequat reduziram significativamente a altura das plantas e o comprimento dos ramos laterais, sem afetar o diâmetro dos capítulos, atrasar o ciclo de produção e causar fitotoxicidade. Entretanto, as plantas não se apresentaram suficientemente baixas e compactas para atender às exigências de qualidade do mercado. Chlormequat (2,0 e 3,0 g L-1) causou fitotoxicidade e daminozide (5,0 g L-1) aumentou o ciclo de produção.Zinnias have good potential to be used as flowering, potted plants, being a quick source of novelty for the floriculture industry with the aid of growth retardants. This study evaluated the effect of growth retardants on development and production of short, compact and attractive plants of potted 'Lilliput' Zinnia elegans, a highly ornamental zinnia with low cost seeds. Trials were set up in randomized blocks, with ten treatments (control and three treatments of each retardant: daminozide, paclobutrazol and chlormequat) and four replications (two pots per experimental unit, with one plant per 0.6-L pot). Paclobutrazol (0.5, 0.75 and 1.0 mg a.i. per pot) and chlormequat (1.0, 2.0 and 3.0 g L-1) were applied as a single drench (40 mL per pot), and daminozide (2.5, 3.75 and 5.0 g L-1) as a single foliar spray to runoff (10 mL per pot), at apical flower bud stage. Daminozide (2.5 and 3.75 g L-1), paclobutrazol (0.5, 0.75 and 1.0 mg a.i. per pot) and chlormequat at 1.0 g L-1 significantly reduced plant height and side branches length, without affecting flower diameter, delaying production cycle and causing phytotoxicity symptoms. However, plants were not short and compact enough to meet market quality demand. Chlormequat (2.0 and 3.0 g L-1) caused phytotoxicity symptoms and daminozide (5.0 g L-1) delayed production cycle