Changing the production chain of Amazonian pirarucu.

This article summarizes these recent findings and envisions how these are impacting the production sector in the short and medium terms. Recent studies in Brazil have addressed the main challenges faced by commercial producers of pirarucu, including breeding, larval rearing, grow-out, feeding, health management, processing and more

Feeding rate and feeding frequency during the grow-out phase of tambaqui (Colossoma macropomum) in earthen ponds.

Adequate feeding protocols are extremely important for the technical and economic feasibility of fish production systems. Two feeding rates, 3% and 4% body weight per day (3%BW and 4%BW), and two feeding frequencies, twice and three times a day, were tested during 84 days at the initial grow-out phase of tambaqui (94.5 ± 6.4 g) in earthen ponds. No mortalities or difference in growth between treatments were observed during the trial. Total feed intake and feed conversion ratio were low in the fish fed at 3%BW. Fat deposition in the fish carcass and concentration of glycogen and lipid vacuoles in the hepatocytes were also low in fish fed at 3%BW. Plasma cholesterol and triglycerides were higher in the fish fed three times a day at 4%BW. Increased concentration of malonaldehyde was observed in the carcass of fish fed three times a day at 4%BW at the end of the storage period. Fish fed twice a day presented higher total feed intake per meal than fish fed three times a day, demonstrating that tambaqui was able to regulate the feed intake to benefit from a low feeding frequency. No difference was observed in pond phytoplankton and zooplankton concentration or sediment chemistry. Fish fed at 3%BW presented higher stomach content weight, demonstrating the contribution of the natural food as a complementary nutrition to tambaqui. Based on the results, tambaqui of 95–350 g reared in earthen ponds may be fed twice a day at 3%BW

Magnetic phases evolution in the LaMn1-xFexO3+y system

We have investigated the crystal structure and magnetic properties for polycrystalline samples of LaMn1-xFexO3+y, in the whole range x=0.0 to x=1.0, prepared by solid state reaction in air. All samples show the ORT-2 orthorhombic structure that suppresses the Jahn-Teller distortion, thus favoring a ferromagnetic (FM) superexchange (SE) interaction between Mn^{3+}-O-Mn^{3+}. For x=0.0 the oxygen excess (y ~ 0.09) produces vacancies in the La and Mn sites and generates a fraction around 18% of Mn^{4+} ions and 82% of the usual Mn^{3+} ions, with possible double exchange interaction between them. The Fe doping in this system is known to produce only stable Fe^{3+} ions. We find an evolution from a fairly strong FM phase with a Curie temperature T_{C} ~ 160 K, for x=0.0, to an antiferromagnetic (AFM) phase with T_{N} = 790 K, for x=1.0, accompanied by clear signatures of a cluster-glass behavior. For intermediate Fe contents a mixed-phase state occurs, with a gradual decrease (increase) of the FM (AFM) phase, accompanied by a systematic transition broadening for 0.2 < x < 0.7. A model based on the expected exchange interaction among the various magnetic-ion types, accounts very well for the saturation-magnetization dependence on Fe doping.Comment: 27 pages, 9 figure

Efeito do diluidor e da temperatura de congelação sobre o sêmen congelado de ovino da raça Santa Inês.

Objetivou-se verificar a influência do tipo de diluidor e da temperatura sobre motilidade do sêmen ovino. A coleta do sêmen foi efetuada uma vez por semana em cinco ovinos da raça Santa Inês, após feito um pool dos ejaculados e avaliado quanto ao volume, à motilidade, vigor, concentração e diluído no Leite e Tris. As amostras foram envasadas em palhetas de 0,25 ml e congeladas em três temperaturas (- 79o C, -90o C, -120o C) no equipamento TK 3000. Quando atingida a primeira temperatura, um grupo de palhetas foi transferido para o botijão criogênico e assim sucessivamente, para às demais temperaturas testadas. Após 30 dias, as palhetas foram descongeladas e o sêmen avaliado pelo método CASA. Procedeu-se a ANOVA para testar o efeito da temperatura de congelação sobre os diluidores. Para o diluidor leite, a motilidade progressiva e a percentagem de espermatozóide rápidos diferiu significativamente para temperatura de -79o C em relação às de -90o C e -120o C. No diluidor Tris não houve diferença significativa entre as temperaturas de congelação, entretanto foi significativo e superior ao diluidor a base leite em todas as temperaturas testadas. O diluidor Tris e a temperatura de congelação de -79o C mostraram ser o protocolo de congelação mais apropriado para sêmen de carneiros Santa Inês, entretanto estudos utilizando a inseminação artificial precisam ser conduzidos para validar sua qualidade. Abstract:: This study aimed to verify the influence of the temperature and the extender type on the motility of ram semen. The semen was collected a time per week in five ?Santa Inês? ram, after it was made one pool of the ejaculated and evaluated how much to the volume, motility, vigor, concentration and diluted with Milk and Tris.The samples were stored in straw of 0,25 mL to be frozen in three temperatures (-79°C,-90°C,-120°C) employing the TK 3000 equipment. When reached the first temperature, a group of straws was transferred to the cryogenic container and thus successively, for the the others tested temperatures. After 30 days, the straws had been thawed and the semen evaluated for the CASA method. It was used the ANOVA to test the effect of the temperature of freezing on the extenders. For the Milk, the progressive motility and the fast spermatozoid percentage for the temperature of -79°C differed significantly when compared to the temperatures of -90°C and -120°C. In the extender Tris did not have significant difference between the temperatures of freezing, however it was significant and superior to the extender milk in all tested temperatures. The extender Tris and the freezing temperature of -79°C showed to be the more appropriate freezing protocol for ?Santa Inês? ram semen. However more studies using the artificial insemination need to be lead to validate its quality

Thermodynamics of Decaying Vacuum Cosmologies

The thermodynamic behavior of vacuum decaying cosmologies is investigated within a manifestly covariant formulation. Such a process corresponds to a continuous irreversible energy flow from the vacuum component to the created matter constituents. It is shown that if the specific entropy per particle remains constant during the process, the equilibrium relations are preserved. In particular, if the vacuum decays into photons, the energy density $\rho$ and average number density of photons $n$ scale with the temperature as $\rho \sim T^{4}$ and $n \sim T^{3}$. The temperature law is determined and a generalized Planckian type form of the spectrum, which is preserved in the course of the evolution, is also proposed. Some consequences of these results for decaying vacuum FRW type cosmologies as well as for models with ``adiabatic'' photon creation are discussed.Comment: 21 pages, uses LATE

Simple implementation of complex functionals: scaled selfconsistency

We explore and compare three approximate schemes allowing simple implementation of complex density functionals by making use of selfconsistent implementation of simpler functionals: (i) post-LDA evaluation of complex functionals at the LDA densities (or those of other simple functionals); (ii) application of a global scaling factor to the potential of the simple functional; and (iii) application of a local scaling factor to that potential. Option (i) is a common choice in density-functional calculations. Option (ii) was recently proposed by Cafiero and Gonzalez. We here put their proposal on a more rigorous basis, by deriving it, and explaining why it works, directly from the theorems of density-functional theory. Option (iii) is proposed here for the first time. We provide detailed comparisons of the three approaches among each other and with fully selfconsistent implementations for Hartree, local-density, generalized-gradient, self-interaction corrected, and meta-generalized-gradient approximations, for atoms, ions, quantum wells and model Hamiltonians. Scaled approaches turn out to be, on average, better than post-approaches, and unlike these also provide corrections to eigenvalues and orbitals. Scaled selfconsistency thus opens the possibility of efficient and reliable implementation of density functionals of hitherto unprecedented complexity.Comment: 12 pages, 1 figur