Energy exchanges in a damped Langevin-like system with two thermal baths and an athermal reservoir

We study the properties of energy transfers in a Langevin-like model which describes an inertial particle in a one-dimensional harmonic potential and subjected to two heat baths and one athermal environment. The thermal noises are white and Gaussian, and the temperatures of heat reservoirs are different. The athermal medium act through an external non-Gaussian noise of Poisson type. We discuss the long-time behavior of first cumulants of time-integrated power due to the athermal reservoir. The averages and covariances of heat exchanged with thermal baths are also evaluated for stationary states. The properties of these cumulants are investigated in terms of the characteristics of external noise.Comment: 23 pages, 7 figure

Appetite for self-destruction: suicidal biting as a nest defense strategy in Trigona stingless bees

Self-sacrificial behavior represents an extreme and relatively uncommon form of altruism in worker insects. It can occur, however, when inclusive fitness benefits are high, such as when defending the nest. We studied nest defense behaviors in stingless bees, which live in eusocial colonies subject to predation. We introduced a target flag to nest entrances to elicit defensive responses and quantified four measures of defensivity in 12 stingless bee species in São Paulo State, Brazil. These included three Trigona species, which are locally known for their aggression. Species varied significantly in their attack probability (cross species range = 0–1, P < 0.001), attack latency (7.0–23.5 s, P = 0.002), biting duration of individual bees (3.5–508.7 s, P < 0.001), and number of attackers (1.0–10.8, P < 0.001). A “suicide” bioassay on the six most aggressive species determined the proportion of workers willing to suffer fatal damage rather than disengage from an intruder. All six species had at least some suicidal individuals (7–83 %, P < 0.001), reaching 83 % in Trigona hyalinata. Biting pain was positively correlated with an index of overall aggression (P = 0.002). Microscopic examination revealed that all three Trigona species had five sharp teeth per mandible, a possible defensive adaptation and cause of increased pain. Suicidal defense via biting is a new example of self-sacrificial altruism and has both parallels and differences with other self-sacrificial worker insects, such as the honey bee. Our results indicate that suicidal biting may be a widespread defense strategy in stingless bees, but it is not universal

Ácido giberélico no desenvolvimento in vitro de embriões imaturos de tangerineira Cleópatra.

A cultura in vitro de embriões é uma técnica da biotecnologia vegetal que tem sido utilizada na tentativa de contornar os problemas relacionados à poliembrionia dos citros. Esta técnica permite o cultivo de todos os embriões presentes numa semente, dentre os quais se encontra aquele de natureza híbrida que, numa fase posterior, poderá ser identificado

Germinação e vigor de sementes de cenoura sob condições de altas temperaturas.

Made available in DSpace on 2011-04-09T16:14:36Z (GMT). No. of bitstreams: 1 pereiragermina.pdf: 973850 bytes, checksum: a7ac80756c04e0a17006bcc880016f30 (MD5) Previous issue date: 2007-10-1

Metodologia de criação do parasitóide exótico: Diachasmimorpha longicaudata (Hymenoptera:braconidae), visando estudos em laboratório e em campo.

O parasitóide Diachasmimorpha longicaudata foi introduzido pela primeira vez no Brasil pela Embrapa Mandioca e Fruticultura, em setembro de 1994. O objetivo da introdução foi o controle biológico de moscas-das-frutas neotropicais. A metodologia foi desenvolvida para aumentar a população desse agente sob condições de laboratório. Larvas de ultimo estádio de Ceratitis capitata foram usadas como hospedeiro do parasitóide. As larvas foram colocadas em "unidades de parasitismo" confinadas em gaiolas de 12 x 15cm. Os parasitóides foram alimentados com dieta artificial e agua. A quantidade de larvas expostas ao parasitismo foi padronizada em Becker de 7,5ml preenchido em 75% de sua capacidade com larvas de C, capitata. As unidades de parasitismo, contendo larvas de C. capitata foram expostas durante 1 hora ao parasitismo de 45 casais sexualmente maduros. Três novas unidades de parasitismo foram expostas durante o dia em diferentes horários. Este processo foi repetido durante dez dias

Comparison of esters determination techniques in cachaça

An analytical comparison of three different techniques for quantitative profile of esters in cachaça is reported. The Ministério da Agricultura Pecuária e Abastecimento (MAPA) recommends the use of GC/FID or volumetry. Despite being laborious and lacking in chemical speciation, the volumetric technique for total ester content shows to be appropriate, reproducible, and accurate for the analysis of cachaça. However, the GC/FID suggested by MAPA, considering only ethyl acetate, shows inaccuracy, underestimating the total ester content by a median factor of 72%, mainly due to the absence of ethyl lactate analysis. On the other hand, the GC/MS technique that comprises the analysis and speciation of nine esters, including ethyl lactate, proved to be reproducible, simple, fast and accurate for the analysis of total ester content in cachaça. Thus, the total ester content results obtained using GC/FID must be considered with precaution.FAPESPCNP

Noncommutative fields in three dimensions and mass generation

We apply the noncommutative fields method for gauge theory in three dimensions where the Chern-Simons term is generated in the three-dimensional electrodynamics. Under the same procedure, the Chern-Simons term is shown to be cancelled in the Maxwell-Chern-Simons theory for the appropriate value of the noncommutativity parameter. Hence the mutual interchange between Maxwell-Chern-Simons theory and pure Maxwell theory turns out to be generated within this method.Comment: Comments 5 pages, epl, version accepted for publication in Europhysics Letter

Resgate e cultivo in vitro de embriões imaturos de tangerineira ?Cleópatra? (Citrus reshni Hort.).

A poliembrionia, um fenômeno comum a muitas espécies cítricas, limita bastante a obtenção de maior número de híbridos em programas de melhoramento genético de citros. Caracteriza-se pela presença de mais de um embrião numa mesma semente, sendo que a maioria desses embriões é de origem nucelar e dificulta a sobrevivência do indivíduo zigótico, devido à competição que ocorre entre eles.PDF. 090_11