Resumen 17. Actualmente existe la necesidad de utilizar productos alter nativos de origen natural que no afecten negativamente la productividad de las colmenas y que reduzcan la presencia de diversos patógenos. El timol es considerado como el producto natural más utilizado para el tratamiento de la varroasis en todo el mundo y potencialmente eficaz como nosemicida. Por lo tanto, el objetivo de esta investigación fue estudiar el impacto del timol sobre el control de la varroasis y nosemosis en colmenas para la formación de núcleos de fecundación de abejas reina (Apis mellifera). Se utilizaron 65 colmenas en las cuales se cuantificó el nivel de infestación para Varroa, nivel de infección para Nosema y las prevalencias de ambas enfermedades en la población antes y después del tratamiento, basado en 4 aplicaciones de timol al 20% en azúcar glass con intervalo de 7 días. La prevalencia de la varroasis disminuyó al igual que el nivel de infestación post tratamiento (p<0,05). Por el contrario, la prevalencia de la nosemosis (p>0,05) y el nivel de infección de Nosema fueron mayores después del tratamiento (p<0,05). Se concluye que en las colmenas para la formación de núcleos de fecundación de abejas reina, el timol es eficaz contra varroasis pero no contra nosemosis.

Abstract 21. Nowadays, there is a need to identify alternative natural products that do not negatively affect the hive’s productivity and that reduce the presence of various pathogens. Thymol is considered the most natural acaricide against varroasis worldwide, with potential nocemicide effect. Therefore, the objective of this research was to study the impact of thymol on the presence of varroasis and nosemosis on queen mating nucleus hives (Apis mellifera). Sixty five hives were used, in which the level of infestation for Varroa sp, the level of infection for Nosema sp, and the prevalence of both diseases in the population before and after the treatment were determined, based on 4 applications of 20% thymol in icing sugar with a 7-day interval. The prevalence of varroasis and level of Varroa sp infestation decreased after treatment (p<0.05). In contrast, the prevalence of nosemosis (p>0.05) and level of Nosema sp infection were higher after treatment (p<0.05). It can be concluded that, in hives destined for the production of queen mating nucleus, thymol is effective against varroasis but not against nosemosis.

The objective of the present study was to evaluate the antioxidant activity (AA) of four commercial feeds on the AA and oxidative stability (EO) of raw loin meat (Longissimus dorsi) of rabbits of three genotypes (New Zealand, NZ, California, CAL, and NZ* CAL), during three refrigerated storage times (0, 3, and 6 days). The AA of all feeds decreased at 30 days of storage; however, feed 1 showed greater AA (p<0.05). In all genotypes and feeds the AA of the raw loin declined at day 6 of refrigeration, except with NZ*CAL fed feed I.The NZ*CAL genotype showed higher AA fed feed 1 (p<0.05) and lower with feed 3. In contrast, the NZ genotype showed lower AA with feed 1 and higher with feed 3. The NZ*CAL crossbreed meat had the best EO when it received feed 1 and the worst with feed 3. On the other hand, NZ showed the worst EO with feed 1 and the best with fed 3 with respect to NZ*CAL, this indicates that EO improved when AA increased. The NZ genotype showed lower EO with feed 4 during all refrigeration days (p<0.05). In addition, the EO of the raw loin decreased over time in refrigeration (p<0.05). It is suggested feeding NZ*CAL rabbits with feeds with more than 85 % of AA and do not refrigerate raw loin meat more than 6 days to avoid deterioration oxidative of the meat.

El objetivo del presente trabajo fue evaluar el efecto de la actividad antioxidante (AA) de cuatro alimentos comerciales sobre la AA y la estabilidad oxidativa (EO) de lomo crudo (Longissimus dorsi) de conejos de tres genotipos (Nueva-Zelanda, NZ, California, CAL, y NZ*CAL) a tres tiempos de refrigeración (0, 3 y 6 días). La AA de todos los alimentos disminuyó (p<0,05) a los 30 días de su almacenamiento; sin embargo, el alimento 1 presentó la mayor AA (p<0,05). Con todos los genotipos y alimentos, la AA del lomo crudo disminuyó al día 6 de refrigeración excepto con NZ*CAL con el alimento 1. El genotipo NZ*CAL presentó mayor AA con el alimento 1 (p<0,05) y menor con el alimento 3. Contrariamente, el genotipo NZ presentó menor AA con el alimento 1 y mayor con el alimento 3. La cruza NZ*CAL presentó la mejor EO cuando recibió el alimento 1 y la peor cuando recibió el alimento 3. Contrariamente, NZ presentó la peor estabilidad oxidativa con el alimento 1 y la mejor con el alimento 3 con respecto a la cruza, esto indica que la EO mejoró al aumentar la actividad antioxidante. El genotipo NZ presentó la menor EO con el alimento 4 durante todo el periodo de refrigeración (p<0,05). Adicionalmente, la EO del lomo crudo disminuyó al transcurrir el tiempo de refrigeración (p<0,05). Se sugiere alimentar a NZ*CAL con alimentos con más de 85 % de AA y no refrigerar más de 6 días para prevenir el deterioro oxidativo del lomo crudo.

We demonstrate that integral dispersion relations for hadron-hadron scattering amplitudes can be replaced by differential relations, without the usual high-energy approximation. We obtain analytical expressions for the corrections associated with the low energy region and exemplify the applicability of the novel relations in the context of an analytical parametrization for proton-proton and antiproton-proton total cross sections.

By means of an almost model-independent parametrization for the elastic hadron-hadron amplitude, as a function of the energy and the momentum transfer, we obtain good descriptions of the physical quantities that characterize elastic proton-proton and antiproton-proton scattering (total cross section, r parameter and differential cross section). The parametrization is inferred on empirical grounds and selected according to high energy theorems and limits from axiomatic quantum field theory. Based on the predictive character of the approach we present predictions for the above physical quantities at the Brookhaven RHIC, Fermilab Tevatron and CERN LHC energies.

We discuss some formal and practical aspects related to the replacement of Integral Dispersion Relations (IDR) by derivative forms, without high-energy approximations. We first demonstrate that, for a class of functions with physical interest as forward scattering amplitudes, this replacement can be analytically performed, leading to novel Extended Derivative Dispersion Relations (EDDR), which, in principle, are valid for any energy above the physical threshold. We then verify the equivalence between the IDR and EDDR by means of a popular parametrization for total cross sections from proton-proton and antiproton-proton scattering and compare the results with those obtained through other representations for the derivative relations. Critical aspects on the limitations of the whole analysis, from both formal and practical points of view, are also discussed in some detail.

We present the results of several parametrizations to two different ensemble of data on pp total cross sections (<FONT FACE=Symbol>s<img SRC="http:/img/fbpe/bjp/v31n4/07eq01.gif" ></FONT>) at the highest center-of-mass energies (including cosmic-ray information). The results are statistically consistent with two distinct scenarios at high energies. From one ensemble the prediction for the LHC (<img SRC="http:/img/fbpe/bjp/v31n4/07eq02.gif"> = 14 TeV) is<FONT FACE=Symbol>s<img SRC="http:/img/fbpe/bjp/v31n4/07eq01.gif" ></FONT> = 113 ± 5 mb and from the other, <FONT FACE=Symbol>s<img SRC="http:/img/fbpe/bjp/v31n4/07eq01.gif"></FONT> = 140 ± 7 mb. From each parametrization, and making use of derivative analyticity relations (DAR), we determine rho(s) (ratio between the forward real and imaginary parts of the elastic scattering amplitude). A discussion on the optimization of the DAR in terms of a free parameter is also presented. In all cases good descriptions of the experimental data are obtained.