In this study, it is shown that anti-sense suppression of Malus domestica 1-AMINO-CYCLOPROPANE-CARBOXYLASE OXIDASE (MdACO1) resulted in fruit with an ethylene production sufficiently low to be able to assess ripening in the absence of ethylene. Exposure of these fruit to different concentrations of exogenous ethylene showed that flesh softening, volatile biosynthesis, and starch degradation, had differing ethylene sensitivity and dependency. Early ripening events such as the conversion of starch to sugars showed a low dependency for ethylene, but a high sensitivity to low concentrations of ethylene (0.01 μl l−1). By contrast, later ripening events such as flesh softening and ester volatile production showed a high dependency for ethylene but were less sensitive to low concentrations (needing 0.1 μl l−1 for a response). A sustained exposure to ethylene was required to maintain ripening, indicating that the role of ethylene may go beyond that of ripening initiation. These results suggest a conceptual model for the control of individual ripening characters in apple, based on both ethylene dependency and sensitivity.

No abstract

No abstract

The key issues in the design of a multiuser orthogonal frequency division multiplexing (MU-OFDM)-based systems are the subcarrier, power, and the bit allocation. Conventionally, the sum capacity of MU-OFDM is maximized when each subchannel is assigned to the user with the best channel-to-noise ratio for that subchannel, with power subsequently distributed by water-filling algorithm. In this paper, several adaptive resource allocation techniques for multiuser OFDM system under various constraints are analyzed. During the analysis, certain techniques strictly maintain proportional rate among users to achieve high quality-of-service (QoS). Few other techniques maximize the sum capacity by efficiently utilizing the unused subchannels, but it fails to maintain the proportional rate among users and thus poor QoS. To maintain target bit error rate (BER), bit allocation algorithms are also analyzed in this paper. In the proposed algorithm, however, the water-filling power allocation is not fully performed; instead, by adjusting only the water-filling level, the transmit power and number of bits are allocated with low computational complexity. Assuming knowledge of the instantaneous channel gains for all users, a resource allocation scheme for a MU-OFDM-based system to simultaneously provide dual services with different QoS is proposed. The proposed algorithm yields less signal to noise ratio (SNR) to achieve same sum capacity of the existing algorithms.

No abstract