3,891 research outputs found
Effect of photoperiod on body weight gain, and daily energy intake and energy expenditure in Japanese quail (Coturnix c. Japonica)
Effect of photoperiod and food duration on body weight gain, energy intake, energy expenditure, and sexual development were investigated in two strains of Japanese quail (Coturnix c. japonica), bred for meat (broilers) or egg production (layers), from 7 to 71 days of age. In a first experiment chicks were subjected to 18L:6D, 15L:9D, 12L:12D, 9L:15D, or 6L:18D, with ad lib food during the light period. In a second experiment birds were exposed to a long photoperiod (18L:6D or 15L:9D) with ad lib food during part of the light period (first 6 or 9 h, respectively). Longer photoperiods were associated with larger weight gains. In 18L:6D broilers total body weight gain was 262 g compared to 213 g in 6L:18D broilers. In layers, corresponding values were 182 and 131 g. This effect of photoperiod on weight gain was primarily due to the effect of photoperiod on food availability. The photoperiod below which detrimental effects on weight gain occurred was 9L:15D for both strains. Chicks subjected to 9L:15D or 6L:18D exploited crop filling to enhance energy intake. They also decreased nocturnal metabolic rates to a greater extent compared to levels during the light phase than chicks subjected to light periods of 12 h or more. Sexual maturation was stimulated by photoperiod. At the age of 71 days, eight out of nine females subjected to 18L:6D were producing eggs, but none of the 6L:18D females. It is concluded that changes in feeding behavior and energy expenditure shown under short photoperiods are part of a strategy that allow chicks to gain weight continuously.
Rate and Mechanism of the Oxidative Addition of Benzoic Anhydride to Palladium(0) Complexes in DMF
The rate constant of the oxidative addition of the benzoic anhydride (PhCO)2O to [Pd0(PPh3)4] has been determined in DMF and compared to that of phenyl halides and phenyl triflate. The following reactivity order has been established: PhI >> (PhCO)2O > PhOTf > PhBr. The oxidative addition of (PhCO)2O proceeds by activation of one C−O bond. Two acyl-PdII complexes are formed: a neutral complex trans-[(PhCO)Pd(OCOPh)(PPh3)2] and a cationic complex trans-[(PhCO)PdS(PPh3)2]+ (S = DMF) showing that the decarbonylation process is highly endergonic. The exchange of PPh3 by the bidentate ligand dppp does not favor the decarbonylation process.
On the Relativistic Separable Functions for the Breakup Reactions
In the paper the so-called modified Yamaguchi function for the Bethe-Salpeter
equation with a separable kernel is discussed. The type of the functions is
defined by the analytic stucture of the hadron current with breakup - the
reactions with interacting nucleon-nucleon pair in the final state (electro-,
photo-, and nucleon-disintegration of the deuteron).Comment: 4 pages, 2 figures, to be published in EPJ Wo
Gravity tests in the solar system and the Pioneer anomaly
We build up a new phenomenological framework associated with a minimal
generalization of Einsteinian gravitation theory. When linearity, stationarity
and isotropy are assumed, tests in the solar system are characterized by two
potentials which generalize respectively the Newton potential and the parameter
of parametrized post-Newtonian formalism. The new framework seems to
have the capability to account for the Pioneer anomaly besides other gravity
tests.Comment: 5 pages. Accepted version, to appear in Modern Physics Letters
Conformal invariance in 2-dimensional discrete field theory
A discretized massless wave equation in two dimensions, on an appropriately
chosen square lattice, exactly reproduces the solutions of the corresponding
continuous equations. We show that the reason for this exact solution property
is the discrete analog of conformal invariance present in the model, and find
more general field theories on a two-dimensional lattice that exactly solve
their continuous limit equations. These theories describe in general
non-linearly coupled bosonic and fermionic fields and are similar to the
Wess-Zumino-Witten model.Comment: 18 pages, RevTeX, 2 figures included; revision of title and
introductio
Spin-orbital Kondo decoherence by environmental effects in capacitively coupled quantum dot devices
Strong correlation effects in a capacitively coupled double quantum-dot setup
were previously shown to provide the possibility of both entangling spin-charge
degrees of freedom and realizing efficient spin-filtering operations by static
gate-voltage manipulations. Motivated by the use of such a device for quantum
computing, we study the influence of electromagnetic noise on a general
spin-orbital Kondo model, and investigate the conditions for observing
coherent, unitary transport, crucial to warrant efficient spin manipulations.
We find a rich phase diagram, where low-energy properties sensitively depend on
the impedance of the external environment and geometric parameters of the
system. Relevant energy scales related to the Kondo temperature are also
computed in a renormalization-group treatment, allowing to assess the
robustness of the device against environmental effects.Comment: 13 pages, 13 figures. Minor modifications in V
How many photons are needed to distinguish two transparencies?
We give a bound on the minimum number of photons that must be absorbed by any
quantum protocol to distinguish between two transparencies. We show how a
quantum Zeno method in which the angle of rotation is varied at each iteration
can attain this bound in certain situations.Comment: 5 pages, 4 figure
- …