Lorentz-violating dimension-five operator contribution to the black body radiation

We investigate the thermodynamics of a photon gas in an effective field theory model that describes Lorentz violations through dimension-five operators and Horava-Lifshitz theory. We explore the electrodynamics of the model which includes higher order derivatives in the Lagrangian that can modify the dispersion relation for the propagation of the photons. We shall focus on the deformed black body radiation spectrum and modified Stefan-Boltzmann law to address the allowed bounds on the Lorentz-violating parameter.Comment: 8 pages, 6 figures. Version published in PL

Exact Effective action for (1+1)-dimensional fermions in an Abelian background at finite temperature and chemical potential

In this paper we study the effects of a nonzero chemical potential in the effective action for massless fermions in (1+1) dimensions in an abelian gauge field background at finite temperature. We calculate the n-point function and show that the structure of the amplitudes corresponds to a generalization of the structure noted earlier in a calculation without a chemical potential (the associated integrals carry the dependence on the chemical potential). Our calculation shows that the chiral anomaly is unaffected by the presence of a chemical potential at finite temperature. However, unlike the earlier calculation (in the absence of a chemical potential) odd point functions do not vanish. We trace this to the fact that in the presence of a chemical potential the generalized charge conjugation symmetry of the theory allows for such amplitudes. In fact, we find that all the even point functions are even functions of the chemical potential while the odd point functions are odd functions of it which is consistent with this generalized charge conjugation symmetry. We show that the origin of the structure of the amplitudes is best seen from a formulation of the theory in terms of left and right handed spinors. The calculations are also much simpler in this formulation and it clarifies many other aspects of the theory

Comparison of growth and lipid accumulation at three different growth regimes with Desmodesmus sp.

The production of third generation biofuel and use of microalgae as feedstock have recently gained increased attention in the research area in search of more sustainable processes. These microorganisms have characteristics that offer great potential to produce either feedstock to other process or even final use products. They have fast growth rates and accumulation of intracellular metabolites, including lipids. There are three basic types of cultures in which microalgae can develop: autotrophic, heterotrophic and mixotrophic. The objective of this work was to study the growth of the microalgae Desmodesmus sp. in these three types of cultivations in order to establish the most effective farming strain for lipids production. It was observed that the strain had higher yields of biomass and lipids in the mixotrophic cultivation with glucose (10 g L−1) as the carbon source, obtaining 54.5 × 106 cells mL−1 with a growth rate of 0.28 (days−1) and 25.1% of lipids in a 6 day cultivation time9421427COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPsem informação2014/10064-9; 2015/19935-

Carrier relaxation in GaAs v-groove quantum wires and the effects of localization

Carrier relaxation processes have been investigated in GaAs/AlGaAs v-groove quantum wires (QWRs) with a large subband separation (46 meV). Signatures of inhibited carrier relaxation mechanisms are seen in temperature-dependent photoluminescence (PL) and photoluminescence-excitation (PLE) measurements; we observe strong emission from the first excited state of the QWR below ~50 K. This is attributed to reduced inter-subband relaxation via phonon scattering between localized states. Theoretical calculations and experimental results indicate that the pinch-off regions, which provide additional two-dimensional confinement for the QWR structure, have a blocking effect on relaxation mechanisms for certain structures within the v-groove. Time-resolved PL measurements show that efficient carrier relaxation from excited QWR states into the ground state, occurs only at temperatures > 30 K. Values for the low temperature radiative lifetimes of the ground- and first excited-state excitons have been obtained (340 ps and 160 ps respectively), and their corresponding localization lengths along the wire estimated.Comment: 9 pages, 8 figures, submitted to Phys. Rev. B Attempted to correct corrupt figure

Efeito de diferentes avaliadores sobre a acidez titulável medida através do acidímetro de Dornic.

O teste de Dornic titula a acidez do leite, onde amostras com acidez acima de 18° D são consideradas ácidas. Neste procedimento o hidróxido de sódio é usado para neutralizar o ácido do leite. A fenolftaleína é usada como indicador, mostrando a quantidade do álcali necessária para neutralizar o ácido do leite. O indicador permanece incolor quando misturado com uma substância ácida, mas adquire coloração rosa em meio alcalino. Portanto, o álcali é adicionado ao leite até que o mesmo adquirira a coloração rósea. Assim, a leitura do teste por parte do avaliador é feita através da identificação do ponto em que o leite fica rosado. O trabalho, realizado na Embrapa CPPSUL, buscou verificar a influencia do avaliador nos resultados do teste de Dornic. Foram utilizados três avaliadores treinados, sendo analisadas 280 amostras para o avaliador 1 (AVAL1), 273 para o avaliador 2 (AVAL2) e 273 amostras para o avaliador 3(AVAL3), totalizando 826 amostras de leite. Cada avaliador realizou a titulação individualmente, com aliquotas da mesma amostra. As amostras apresentaram em média 15,85 ± 2,73 em graus Dornic (oD). A média e o desvio padrão da acidez titulável em oD foi de 15,68 ± 2,62; 15,41 ± 2,52; 16,46 ± 2,93, para o AVAL1, AVAL2 e AVAL3, respectivamente. Houve diferença significativa (P0,05). Destarte, a acidez titulável em oD sofreu a influência de diferentes avaliadores

Efeito de dois níveis de concentrado nos componentes do leite de vacas jersey em sistema a pasto.

A concentração de constituintes do leite é individualmente influenciada por fatores como dieta, temperatura, estágio de lactação, genética entre outros. Para avaliar o efeito de dois níveis de concentrado sobre os componentes do leite de vacas da raça Jersey, foram analisadas 300 amostras de leite provenientes de vacas mantidas em pastagens cultivadas temperadas e nativas melhoradas durante o período de primavera/verão na oferta de 6 kg por dia de matéria seca para cada 100 kg de peso vivo e recebendo diariamente dois níveis de concentrado comercial (2Kg e 4Kg). Os valores médios e seus respectivos desvios-padrões para a porcentagem de gordura (%GORD), proteína (%PROT) e sólidos totais (%SOL) foram de 4,69 ± 1,37%; 4,02 ± 0,38%; e 14,07 ± 1,75%. Os valores médios para a %GORD, %PROT e %SOL foram de 4,73 ± 1,43%, 4,06 ± 0,39%, e 14,23 ± 1,76%; e de 4,47 ± 0,99%, 3,84 ± 0,25%, e 13,29 ± 1,47%, para o níveis 4Kg e 8Kg de concentrado comercial. Não houve diferença (P=0,23) entre os dois níveis para a %GORD, todavia, houve diferença (P=0,000) para a %PROT e %SOL. As vacas que receberam diariamente 2 Kg de concentrado apresentaram leite com maiores porcentagens de proteína e de sólidos totais comparadas as que receberam 4 Kg de concentrado. O nível de concentrado influenciou a porcentagem de proteína e de sólidos totais no leite de vacas Jersey em sistema a pasto sem, no entanto afetar a porcentagem de gordura

Canopy Changes of Brachiaria Managed Under Continuous Stocking in the Dry-Water Transition

Pasture supplementation is an alternative to take advantage of the forage mass deferred in the rainy season and maintain or provide weight gain in periods of rain absence. The objective was to compare the structural characteristics, mass production, density and population demography of tillers of Urochloa brizantha cv. Paiaguás and Urochloa spp. cv. Convert under fixed and continuous stocking with steers supplemented with pelleted concentrate supplied in the trough or on the ground in the water/dry transition period. The experiment was carried out in the Jatai Federal University, from March to June 2020, in a completely randomized design and a 2 x 2 factorial scheme, using six paddocks/treatment. SAS was used considering repeated measures (RM) at 5% to do variance analysis. There was a significant interaction between Brachiaria and the method of supplementation for basal tiller, aerial and total tiller density. Convert-grass had an average of 551 basal and 577 total tiller/m2. Paiaguas grass presented higher tiller density (1,028 vs. 582 tiller/m2) and higher tiller birth rate (12.92 vs. 9.14%) than Convert. No significant difference was observed between the brachiarias. The average height of Paiaguas-grass was 62.34 cm and 50.70 cm for Convert-grass. The average height was 57.83 cm and on the ground it was 54.90 cm. Supplementation offer method changed Paiaguas canopy. The Convert showed higher leaf and dead mass production but lower weeds despite its smaller tillering

Efeito do nível de 4 e 8 kg de concentrado na dieta de vacas jersey sobre a incidência de leite instável não ácido.

No Leite instável não ácido (LINA) ocorre perda da estabilidade da proteína sem apresentar acidez elevada. As causas conhecidas de alterações na estabilidade do leite estão associadas à estação do ano, dieta e estágio da lactação. Na Embrapa Pecuária Sul, vacas da raça Jersey mantidas em pastagens temperadas na oferta diária de 6 kg de MS dia por 100 kg de peso vivo, foram suplementadas diariamente com 4 Kg ou 8 Kg/dia de concentrado. Do total de 1.743 amostras de leite, 81,9% (n=1421) e 18,1% (n=315) foram negativas para a LINA, para os níveis 4 Kg e 8 Kg de concentrado, respectivamente, totalizando 1.736 amostras. Somente ocorreram sete casos de LINA para o nível 4 Kg de concentrado. Dentre esses casos de incidência de LINA, duas amostras ocorreram na concentração de álcool 76°, 2 amostras na concentração 78º, e três amostras na concentração 80º. Não houve diferença (P>0,05) entre os dois níveis de concentrado (4Kg e 8Kg) para a incidência do LINA. Todavia, houve efeito do período (P<0,01) sobre as variáveis analisadas. As amostras coletadas dia 1° de julho de 2010 diferiram (P<0,01) dos demais períodos, pois neste período ocorreu a maioria dos casos de incidência de LINA (n=4), representando 57,1%. No período representado pelo dia 04 de junho, ocorreram 42,9% dos casos de LINA (n=3), mas o mesmo não diferiu (P<0,05) dos demais. Os níveis de concentrado 4 Kg e 8 Kg, para vacas Jersey mantidas em pastagens temperadas, não influenciaram a incidência de LINA

Abundance Gradients and the Formation of the Milky Way

In this paper we adopt a chemical evolution model, which is an improved version of the Chiappini, Matteucci and Gratton (1997) model, assuming two main accretion episodes for the formation of the Galaxy. The present model takes into account in more detail than previously the halo density distribution and explores the effects of a threshold density in the star formation process, during both the halo and disk phases. In the comparison between model predictions and available data, we have focused our attention on abundance gradients as well as gas, stellar and star formation rate distributions along the disk. We suggest that the mechanism for the formation of the halo leaves detectable imprints on the chemical properties of the outer regions of the disk, whereas the evolution of the halo and the inner disk are almost completely disentangled. This is due to the fact that the halo and disk densities are comparable at large Galactocentric distances and therefore the gas lost from the halo can substantially contribute to building up the outer disk. We also show that the existence of a threshold density for the star formation rate, both in the halo and disk phase, is necessary to reproduce the majority of observational data in the solar vicinity and in the whole disk. Moreover, we predict that the abundance gradients along the Galactic disk must have increased with time and that the average [alpha/Fe] ratio in stars (halo plus disk) slightly decrease going from 4 to 10 Kpcs from the Galactic center. We also show that the same ratios increase substantially towards the outermost disk regions and the expected scatter in the stellar ages decreases, because the outermost regions are dominated by halo stars.Comment: 41 pages (including the figures), To be published in Ap