Relativistic effects and quasipotential equations

We compare the scattering amplitude resulting from the several quasipotential equations for scalar particles. We consider the Blankenbecler-Sugar, Spectator, Thompson, Erkelenz-Holinde and Equal-Time equations, which were solved numerically without decomposition into partial waves. We analyze both negative-energy state components of the propagators and retardation effects. We found that the scattering solutions of the Spectator and the Equal-Time equations are very close to the nonrelativistic solution even at high energies. The overall relativistic effect increases with the energy. The width of the band for the relative uncertainty in the real part of the scattering $T$ matrix, due to different dynamical equations, is largest for backward-scattering angles where it can be as large as 40%.Comment: Accepted for publication in Phys. Rev.

Selection among and within half-sib families in "Dentado Composto" maize variety for resistance to S. frugiperda and H. zea. ll cycle.

Estudou-se a obtenção de parâmetros genéticos para alguns caracteres de planta e espiga de milho (Zea mays L.) cv. Composto Dentado. O material é do segundo ciclo de seleção entre e dentro de famílias de meios-irmãos. Avaliaram-se 400 progénies num delineamento de látice simples 10 x 10 com uma repetição por local: Caruaru e S. Bento do Una, PE. Os experimentos não receberam tratamentos fitossanitários, e foram isolados das áreas que receberam tratamentos com inseticidas, utilizando-se infestações naturais. Foram coletados os dados para: altura da planta (AP) e da espiga (AE), número de espigas por planta (NE) e de espigas mal empalhadas (NEME), danos causados por H. zea (HZ) e S. frugiperda (SF), e produção de grãos (PG). As estimativas de variância genética aditiva foram altas (P < 0,05) para AP, AE e PG, e baixas para os demais caracteres. Tendo em vista os baixos valores encontrados para a variabilidade genética concernentes aos caracteres HZ e SF, é necessário um controle ambiental mais eficiente nas avaliações das progénies.The obtention of genetic parameters was studied for some characters of plant and ear of maize (Zea mays L.) cv. Composto Dentado. The material came from the second cicle of selection inter and intra families of half-sibs. Four hundred progenies were evaluated in a 10 x 10 simple lattice design, with one replicate for each place: Caruaru and São Bento do Una, PE, Brazil. The experiments did not receive phytosanitary treatments. They were isolated from the areas that received insecticide applications and lhe natural infestation was used. Data were colected for: plant height (PH), ear height (EH), number of ears per plant (NE), number of ear with loosed husk (NELH), S.frugiperda damage (SFD), H. Zea damage (HZD) and grain yield (GY). The variance analysis showed significance (P < 0.01) for all characters studied except for SFD. The estimate values for the additive genetic variance were high for PH, EH and GY and low for Lhe other characters. Considering the low values found for genetic variability concerning the characters HZ and SF, an environmental control more efficient ia the progenie evaluations is needed