Age-dependent winner-loser effects in a mangrove rivulus fish, Kryptolebias marmoratus.

The outcomes of recent fights can provide individuals information about their relative fighting ability and affect their contest decisions (winner-loser effects). Most studies investigate the presence/absence of the effects in populations/species, but here we examine how they vary between individuals of a species in response to age-dependent growth rate. Many animals' fighting ability is highly dependent on body size, so rapid growth makes information from previous fights unreliable. Furthermore, fast-growing individuals are often at earlier developmental stages and are relatively smaller and weaker than most other individuals but are growing larger and stronger quickly. We therefore predicted winner-loser effects to be less detectable in individuals with high than low growth rates and to decay more quickly. Fast-growing individuals should also display stronger winner than loser effects, because a victory when small indicates a strength which will grow, whereas a loss might soon become irrelevant. We tested these predictions using naïve individuals of a mangrove killifish, Kryptolebias marmoratus, in different growth stages. Measures of contest intensity revealed winner/loser effects only for slow-growth individuals. Both fast- and slow-growth fish with a winning experience won more of the subsequent non-escalated contests than those with a losing experience; in fast-growth individuals this effect disappeared in 3 days, but in slow-growth fish it did not. Fast-growth individuals also displayed winner effects but not loser effects. The fish therefore responded to their contest experiences in a way which reflected value of the information from these experiences to them, consistent with our predictions.

[Efficacy evaluation of acupoints massage on asthenopia of video display terminal under different exposure dose].

OBJECTIVE: To observe the efficacy differences of acupoints massage for asthenopia of video display terminal (VDT) under different exposure dose. METHODS: One hundred and two cases (204 eyes) were divided into a low exposure group and a high exposure group, fifty-one cases in each group. The same intervention of acupoints massage on Cuanzhu (BL 2), Jingming (BL 1), Sizhukong (TE 23), Sibai (ST 2) and Taiyang(EX-HN 5) were given to the two groups, one acupoint for 5 min and once everyday, one month of which made a course. The symptom score, tear film break-up time (BUT) and Schirmer I test(SIT) were observed before and after treatment. RESULTS: (1) The correlation coefficient of cubic curve model of the exposure dose was the biggest with symptom improvement index (P = 0.000), which indicated that the lower VDT exposure index was, the more obvious the symptom improved. The symptom improvement indices of low exposure group and high exposure group, which were (52.31 +/- 16.65)% and (28.93 +/- 13.35)% respectively, were statistical significant difference (P = 0.000). (2) Compared to before treatment, the levels of BUT and SIT in the two groups were both significantly higher (P < 0.05). Compared with the high exposure group, the levels of BUT and SIT in the low exposure group were increased by 0.826 s (P = 0.022) and 1.029 mm (P = 0.033), respectively, after the impact of BUT and SIT was corrected before the research. CONCLUSION: The acupoints massage can improve the symptoms and ocular physiology for patients with VDT asthenpia, and it is more effective for the low exposure cases.