Pollinator shift and reproductive performance of the qinghai-tibetan plateau endemic and endangered Swertia przewalskii (Gentianaceae)

Reproductive failure results in many plant species becoming endangered. However, little is known of how and to what extent pollinator shifts affect reproductive performance of endangered species as a result of the artificial introduction of alien insects. In this study we examined breeding systems, visitor species, visiting frequency and seed set coefficients of Swertia przewalskii in two years that had different dominant pollinator species (native vs. alien). Flowers of this species were protandrous and herkogamous and insects were needed for the production of seeds. The stigmatic receptivity of this species was shorter than for other gentians. No significant difference in seed set coefficient was found for hand-pollinated plants between the two years, indicating that pollinator shift only had a minor effect on this plant's breeding system. The commonest pollinators in 2002 were native bumblebees, alien honeybees and occasional solitary bees, however, only alien honeybees were observed in 2004. The flower visitation rate in both years was relatively high, although the total visit frequency decreased significantly in 2004. The control flowers without any treatment produced significantly fewer seed sets in 2004 than in 2002. In the past decade the seed production of this species may have partly decreased due to pollination by alien honeybees, however, we suggest that they might have acted as alternative pollinators ensuring seed production of S. przewalskii when native pollinators were unavailable. The main reason that this plant is endangered is probably the result of habitat destruction, but changes in land use, namely intensified agricultural practice and unfavorable animal husbandry have also contributed to its decline. We recommend that in-situ conservation, including the establishment of a protected area, is the best way to preserve this species effectively.

Enhanced anthocyanin production by repeated-batch culture of strawberry cells with medium shift

Repeated-batch cultures of strawberry cells (Fragaria ananassa cv. Shikinari) subjected to four medium-shift procedures (constant LS medium, constant B5 medium, alternation between LS and B5 starting from LS and alternation between LS and B5 starting from B5) were investigated for the enhanced anthocyanin productivity. To determine the optimum period for repeated batch cultures, two medium-shift periods of 9 and 14 days were studied, which represent the end of the exponential growth phase and the stationary phase. By comparison with the corresponding batch cultures, higher anthocyanin productivity was achieved for all the repeated-batch cultures at a 9-day medium-shift period. The average anthocyanin productivity was enhanced 1.7-and 1.76-fold by repeated-batch cultures in constant LS and constant B5 medium at a 9-day shift period for 45 days, respectively. No further improvement was observed when the medium was alternated between LS (the growth medium) and B5 (the production medium). Anthocyanin production was unstable at a 14-day shift period regardless of the medium-shift procedures. The results show that it is feasible to improve anthocyanin production by a repeated-batch culture of strawberry cells.

A two-stage process with temperature-shift for enhanced anthocyanin production in strawberry cell suspension cultures

A two-stage process with temperature-shift has been developed to enhance the anthocyanin yield in suspension cultures of strawberry cells. The effect of the temperature-shift interval and the shift-time point was investigated for the optimization of this strategy. In this process, strawberry cells were grown at 30 degrees C (the optimum temperature for cell growth) for a certain period as the first stage, with the temperature shifted to a lower temperature for the second stage. In response to the temperature shift-down, anthocyanin synthesis was stimulated and a higher content could be achieved than that at both boundary temperatures but cell growth was suppressed. When the lower boundary temperature was decreased, cell growth was lowered and a delayed, sustained maximum anthocyanin content was achieved. Anthocyanin synthesis was strongly influenced by the shift-time point but cell growth was not. Consequently, the maximum anthocyanin content of 2.7 mg.g-fresh cell(-1) was obtained on day 9 by a temperature-shift from 30 degrees C, after 3-d culture, to 15 degrees C. The highest anthocyanin yield of 318 mg.L-1 on day 12 was achieved when the temperature was shifted from 30 degrees C, after 5-d culture, to 20 degrees C. For a global optimization of both the yield and productivity, the optimum anthocyanin yield and productivity of 272 mg.L-1 and 30.2 mg.L-1.d(-1) on day 9 were achieved by a two-stage culture with a temperature-shift from 30 degrees C after 3 d to 20 degrees C.

重读和动词隐含因果性对代词加工的影响

Numerous studies have shown that accentuation and implicit verb causality influenced pronoun resolution. However, many researchers cannot agree on the time course, as well as they know little about the interaction between the two types of information during comprehending Chinese sentences. The study aimed to explore the effects of accentuation and implicit verb causality on the pronoun processing during spoken Chinese sentences comprehension as well as their time courses, using auditory moving window technique and cross-modal probe paradigm. The main results were: 1) The reading time of the second clause in stressed pronoun condition was significantly longer than that in unstressed pronoun condition. Accentuation influenced the activation level of candidate antecedents. 2) Implicit verb causality influenced the pronoun interpretation during spoken Chinese sentences comprehension. It also affected the activation level of candidate antecedents immediately after people heard the pronoun. 3) There was “the first-mentioned effect” in spoken Chinese sentences comprehension. The effect seemed as if a general phenomenon during the pronoun processing. 4) Accentuation, Implicit verb causality and the first-mentioned effect interacted during the pronoun processing and spoken Chinese sentences comprehension. This study supported the focus hypothesis, indicating accentuation could shift the center of attention even in nonparallel-structure sentences; implicit verb causality influences the pronoun processing immediately; there was interaction between accentuation and implicit verb causality during spoken sentence comprehension.

手持通信设备的多通道文本输入研究

Recently，Handheld Communication Devices is developing very fast, extending in users and spreading in application fields, and has an promising future. This study investigated the acceptance of the multimodal text entry method and the behavioral characteristics when using it. Based on the general information process model of a bimodal system and the human factor studies about the multimodal map system, the present study mainly focused on the hand-speech bimodal text entry method. For acceptance, the study investigated the subjective perception of the accuracy of speech recognition by Wizard of Oz (WOz) experiment and a questionnaire. Results showed that there was a linear relationship between the speech recognition accuracy and the subjective accuracy. Furthermore, as the familiarity increasing, the difference between the acceptable accuracy and the subjective accuracy gradually decreased. In addition, the similarity of meaning between the outcome of speech recognition and the correct sentences was an important referential criterion. The second study investigated three aspects of the bimodal text entry method, including input, error recovery and modal shifts. The first experiment aimed to find the behavioral characteristics of user when doing error recovery task. Results indicated that participants preferred to correct the error by handwriting, which had no relationship with the input modality. The second experiment aimed to discover the behavioral characteristics of users when doing text entry in various types of text. Results showed that users preferred to speech input in both words and sentences conditions, which was highly consistent among individuals, while no significant difference was found between handwriting and speech input in the character condition. Participants used more direct strategy than jumping strategy to deal with mixed text, especially for the Chinese-English mixed type. The third experiment examined the cognitive load in the different modal shifts, results suggesting that there were significant differences between different shifts. Moreover, relevant little time was needed in the Shift from speech input to hand input. Based on the main findings, implications were discussed as follows: Firstly, when evaluating a speech recognition system, attention should be paid to the fact that the speech recognition accuracy was not equal to the subjective accuracy. Secondly, in order to make a speech input system more acceptable, a good method is to train and supply the feedback for the accuracy in training, which improving the familiarity and sensitivity to the system. Thirdly, both the universal and individual behavioral patterns were taken into consideration to improve the error recovery method. Fourthly, easing the study and the use of speech input, the operations of speech input should be simpler. Fifthly, more convenient text input method for non-Chinese text entry should be provided. Finally, the shifting time between hand input and speech input provides an important parameter for the design of automatic-evoked speech recognition system.