The recent outbreak of avian influenza in the poultry sector of Cameroon has raised a concern about the level of implementation of biosecurity measures (BM) on poultry farms. Therefore, a study using a questionnaire on 102 randomly selected poultry farms was undertaken. Some measures with high adoption levels (> 90%) included "protection of airing openings of poultry barns by a wire mesh," "no external animal allowed to enter the farm," "respect of all-in all-out principle," "functional footbath," "rodent control," and "feedstuff protection from access to rodents." The least implemented measures (less than 20%) were "wearing of dedicated clothing (clean coveralls and boots) by workers," "disinfection of visitors," and "presence of storage room for dead animals." Only for "isolation" component of biosecurity, compliance with biosecurity measures was good, with more than 50% of farms having an adoption rate greater than 75%. The mean biosecurity score for the assessed farms was 19.29 ± 1.89 for a maximum score of 38 points. The score was significantly and positively correlated (p < 0.05) with the number of chicken and the geographic location of farms. The other results showed that the mean number of broiler per cycle was 550.82 ± 76 for a stocking density of 27.20 ± 6.64 birds per m. In conclusion, broiler production in the Western highland is dominated by small-scale units with low level of biosecurity practices positively and significantly (p < 0.05) influenced by some production characteristics. To improve biosecurity practices in the area, efforts must focus on measures concerning "sanitation" and "traffic control" components of biosecurity.
This present issue is an extension of the work of Y. Xiao-Zhong <i>et al</i>. who investigated the influence of constant external magnetic field on the decoherence of a central electron spin of atom coupled to an anti-ferromagnetic environment. We have shown in this work that the character variability of the field induces oscillations amongst the eigen modes of the environment. This observation is made via the derivation of the transition probability density of state, a manner by which critical parameters (parameters where transition occur) of the system could be obtained as it shows resonance peak. We equally observed that the two different magnons modes resulting from the frequency splitting via the application of the time-varying external B-Field, exhibit each a resonant peak of similar amplitude at different temperature ranges. This additional information shows that the probability for the central spin system to remain in its initially prepared diabatic state is enhanced for some temperature ranges for the corresponding two magnon modes. Hence, these temperature ranges where the probability density is maximum could save as decoherence free environment; an important requirement for the implementation of quantum computation and information processing in solid state circuitry. The theoretical and numerical results presented for the decoherence time and the probability density are that of a decohered central electron spin coupled to an anti-ferromagnetic spin bath. The theory is based on a spin wave approximation and on the density matrix using both transformations of Bloch, Primakov and Bogoliobuv in the adiabatic limit
In this paper, we calculate the time evolution of the quantum mechanical state of a bound magnetopolaron in a modified cylindrical quantum dot. In the condition of strong coupling, we investigate the eigen energies and the eigenfunctions of the ground state and the first excited state, respectively. This system may be employed as a two-level quantum system qubit and therefore be helpful for storage of information. The Shannon entropy is used to investigate the decoherence of the qubit when the latter is in the superposition state of the ground and the first excited states. We also study the influence of the electric field, the magnetic field and the Coulomb potential on the decoherence time, eigen energies of the ground state, and the first excited state. It is shown that, the phonon spontaneous emission causes the decoherence of the qubit. We plot the decay of the density matrix of the qubit and the coherent term of the density matrix element [Formula: see text] (or [Formula: see text]) in a function of time for different coupling strengths, confinement lengths and dispersion coefficient.
We examine the magnetopolaron state in a cylindrical quantum dot with a transverse parabolic potential and a high rectangular potential well in the longitudinal direction. The quadratic dependence of the magnetopolaron energy versus Fröhlich electron–phonon coupling constant for different cyclotron radii and constant structure radius is modulated by a logarithmic function seems to depend on the Fröhlich coupling constant. The same law is seen in the case of magnetopolaron energy versus Fröhlich electron–phonon coupling constant for different structure radii and constant cyclotron radius. The energies are seen to be lifted in different fashions in the case of the structure and cyclotron radii. The high degrees of confinement (or high magnetic field) lead to an enhancement in the effective electron–phonon coupling that in turn brings about the possibility that in spite of weak polar coupling as in GaAS say, the polaron problem may also have strong-coupling counterparts arising from confinement or magnetic field effects. The polaron mass increases with increasing Fröhlich electron–phonon coupling constant. The dependence seems to be fourth-order law of the Fröhlich coupling constant modulated by a logarithmic function.
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