72 research outputs found

    Effects of light and temperature on growth and flowering of carnation (Dianthus caryophyllus L.)

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    Both a long photoperiod and strong illumination strongly promoted growth and flowering. These conditions diminished the number of leaf pairs below the flower and promoted growth of flower buds from initiation to bud emergence from the leaves. The subsequent phases to anthesis were little affected by photoperiod and light intensity. Other characters such as stem length, stem diameter, leaf length and width, flower diameter and petal number were affected more by strength than by duration of illumination.Flower induction was promoted by cold (5°C). But as soon as the flower had been initiated, its development was promoted by warmth.Carnations were planted the year round at two-week intervals. The shortest time between planting and harvest was 4 months, after planting in April, the longest 8 months, after planting in September. Treatment at 5°C for three weeks reduced the time to the first crop when plants were started between July and November and increased it in plantings between January and June. There was no residual effect of cold on the second crop

    Cold dark matter in brane cosmology scenario

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    We analyze the dark matter problem in the context of brane cosmology. We investigate the impact of the non-conventional brane cosmology on the relic abundance of non-relativistic stable particles in high and low reheating scenarios. We show that in case of high reheating temperature, the brane cosmology may enhance the dark matter relic density by many order of magnitudes and a stringent lower bound on the five dimensional scale is obtained. We also consider low reheating temperature scenarios with chemical equilibrium and non-equilibrium. We emphasize that in non-equilibrium case, the resulting relic density is very small. While with equilibrium, it is increased by a factor of O(10^2) with respect to the standard thermal production. Therefore, dark matter particles with large cross section, which is favored by detection expirements, can be consistent with the recent relic density observational limits.Comment: 14 pages, 1 figur

    Phenomenology of strangeness production at high energies

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    The strange-quark occupation factor (γs\gamma_s) is determined from the statistical fit of the multiplicity ratio K+/π+\mathrm{K}^+/\pi^+ in a wide range of nucleon-nucleon center-of-mass energies (sNN\sqrt{s_{NN}}). From this single-strange-quark-subsystem, γs(sNN)\gamma_s(\sqrt{s_{NN}}) was parametrized as a damped trigonometric functionality and successfully implemented to the hadron resonance gas model, at chemical semi-equilibrium. Various particle ratios including K−/π−\mathrm{K}^-/\pi^-, Λ/π−\mathrm{\Lambda}/\pi^-, and Λˉ/π−\mathrm{\bar{\Lambda}}/\pi^- are well reproduced. The phenomenology of γs(sNN)\gamma_s(\sqrt{s_{NN}}) suggests that, the hadrons (γs\gamma_s raises) at sNN≃7 \sqrt{s_{NN}} \simeq 7~GeV seems to undergo a phase transition to a mixed phase (γs\gamma_s declines), which is then derived into partons (γs\gamma_s remains unchanged with increasing sNN\sqrt{s_{NN}}), at sNN≃20 \sqrt{s_{NN}} \simeq 20~GeV.Comment: 6 pages, 2 figures, accepted for publication in EP
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