27 research outputs found
Quasi-particle re-summation and integral gap equation in thermal field theory
A new approach to quantum field theory at finite temperature and density in
arbitrary space-time dimension D is developed. We focus mainly on relativistic
theories, but the approach applies to non-relativistic ones as well.
In this quasi-particle re-summation, the free energy takes the free-field
form but with the one-particle energy replaced by \vep
(\vec{k}), the latter satisfying a temperature-dependent integral equation
with kernel related to a zero temperature form-factor of the trace of
stress-energy tensor. For 2D integrable theories the approach reduces to the
thermodynamic Bethe ansatz. For relativistic theories, a thermal c-function
is defined for any based on the coefficient of the black
body radiation formula. Thermodynamical constraints on it's flow are presented,
showing that it can violate a ``c-theorem'' even in 2D. At a fixed point
is a function of thermal gap parameters which generalizes Roger's
dilogarithm to higher dimensions. This points to a strategy for classifying
rational theories based on ``polylogarithmic ladders'' in mathematics, and many
examples are worked out. An argument suggests that the 3D Ising model has
. (In 3D a free fermion has .) Other
applications are discussed, including the free energy of anyons in 2D and 3D,
phase transitions with a chemical potential, and the equation of state for
cosmological dark energy.Comment: Version 4: Published versio
The Physiology of Vasodilatation
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68237/2/10.1177_000331976101200602.pd
Uso da alga Lithothamnium calcareum como fonte alternativa de cálcio nas rações de frangos de corte Use of algae Lithothamnium calcareum as alternative source of calcium in diets for broiler chickens
Objetivou-se, com este trabalho, avaliar o uso da alga Lithothamnium calcareum (Pallas) Areschoug nas rações para frangos de corte de 1 a 21 e 21 a 42 dias de idade, em substituição à fonte de cálcio tradicional (calcário calcÃtico). Para isso, foram utilizados 300 pintos machos, da linhagem Cobb®, que receberam rações contendo o calcário calcÃtico e a alga Lithothamnium calcareum (colhida de inteira e na forma de areia biodentrÃtica) como fontes de cálcio. O delineamento experimental utilizado foi o inteiramente casualizado, com três tratamentos e cinco repetições de 20 aves cada. As variáveis analisadas foram: ganho de peso (g/ave), consumo de ração (g/ave) e conversão alimentar (g/g). No final do experimento foram avaliados os parâmetros ósseos: peso da tÃbia (g), comprimento da tÃbia (mm), diâmetro da tÃbia (mm) e teor de cinzas na tÃbia (%). Na fase inicial (1 a 21 dias) houve efeito (P<0,05) entre os tratamentos para o ganho de peso e conversão alimentar, sendo que o tratamento controle apresentou melhores resultados. Para a fase de crescimento (21 a 42 dias) e perÃodo total (1 a 42 dias) não houve efeito entre os tratamentos estudados. A utilização da alga Lithothamnium calcareum (independente da forma de colheita) em substituição à fonte de cálcio tradicional (calcário calcÃtico) pode ser recomendada para as rações de frangos de corte, sem prejudicar o desempenho zootécnico. Porém, deve-se levar em consideração a viabilidade econômica do uso dessa fonte alternativa nas rações.<br>The objective of this study was to evaluate the use of the algae Lithothamnium calcareum (Pallas) Areschoug in diets for broiler chickens from 1 to 21 and 21 to 42 days, to replace the traditional source of calcium (limestone). 300 male chicks from Cobb® strain, which received diets containing limestone and Lithothamnium calcareum algae (as a whole and as sand biodentritic) were used as sources of calcium. The experimental design was completely randomized, with three treatments and five replicates of 20 birds each. The variables analyzed were: weight gain (g / bird), feed intake (g / bird), feed per again (g / g). At the end of the experiment the bone parameters: weight of the tibia (g), tibia length (mm), diameter of the tibia (mm) and ash content in the tibia (%). Were evaluated in the initial phase (1 to 21 days) there was an effect (P <0.05) between treatments for weight gain and feed per again, and the control treatment showed better results. For the growing phase (21 to 42 days) and total period (1 to 42 days) there was no effect among the treatments studied. The use of the algae Lithothamnium calcareum (independently of the harvest) to replace the traditional source of calcium (limestone) can be recommended for diets of broilers without affecting the growth performance. However, one should take into consideration the economic feasibility of using this alternative source in the diets