Biomedical subjects

Hongliang Ma

Publications and source records attributed to Hongliang Ma.

4 recordsLinked to original sources

PubMed2005

Coherence phenomena in the phase-sensitive optical parametric amplification inside a cavity.

We theoretically and experimentally demonstrate coherence phenomena in optical parametric amplification inside a cavity. The mode splitting in the transmission spectra of a phase-sensitive optical parametric amplifier is observed. Especially, we show that a very narrow dip and peak, which are the shape of a delta function, appear in the transmission profile. The origin of the coherence phenomenon in this system is the interference between the harmonic pump field and the subharmonic seed field in cooperation with dissipation of the cavity.

Journal Article↗

PubMed2003

Suppression of intensity noise of a laser-diode-pumped single-frequency Nd:YVO4 laser by optoelectronic control.

The intensity-noise reduction of a laser-diode-pumped single-frequency ring Nd:YVO4 laser when different optoelectronic control systems are used is theoretically and experimentally investigated. It has been demonstrated that combining two techniques, optoelectronic feedback control of the drive current of the pump laser diode and feed-forward control of the output laser beam, is a good way to significantly suppress the intensity noise of a laser at low frequency.

Journal Article↗

PubMed2002

[Responses of rice (Oryza sativa) growth and its C, N and P composition to FACE (free-air carbon dioxide enrichment) and N, P fertilization].

FACE (Free-air Carbon Dioxide Enrichment) was used to study the effects of elevated CO2 on rice (Oryza sativa) growth, tissue C/N, N and P concentration and uptake at different development stages under two N and two P levels. Results showed that elevated CO2 increased dry matter accumulation in rice stem, ear and root. Leaf dry matter was increased at tillering stage and no significant effect was found at jointing, heading and ripening stages. N concentration of stem and leaf was decreased. Ear N concentration at heading stage was increased but was decreased at ripening stage. No significant effect was found on root N concentration at tillering stage but root N concentration at jointing, heading and ripening was decreased. Leaf P concentration at jointing, heading and ripening was increased but no significant effect was found on P concentration in stem, ear and root. C content in various tissues changed unremarkably and the ratio of C over N (C/N) was increased. Elevated CO2 significantly increased P uptake in aboveground tissues; and increased N uptake, but the difference was not statistically significant. N and P fertilization had no significant effect on various tissue dry biomass. Tissue N content at higher N fertilization was higher than at lower N fertilization but no such effect of P fertilization on tissue P content was found. At higher N fertilization, elevated CO2 increased the ratio of below-ground biomass over above-ground biomass at ripening stage. Possible reasons are discussed for the differences of tissue N and P content and the ratio of below-ground biomass over above-ground biomass between elevated and ambient atmospheric CO2 concentrations.

Air↗

PubMed2002

[Effect of FACE on competition between a C3 crop (rice, Oryza sativa) and a C4 weed (barnyardgrass, Echinochloa crusgalli)].

The growth and competition of a C3 crop rice and a C4 weed, barnyardgrass under FACE(free-air carbon dioxide enrichment) conditions were studied by field experiment. The results showed that under FACE condition, the biomass and yield, leaf number, tiller number, and leaf area index of rice increased, while those of barnyardgrass decreased. Both of the leaf area indexed of rice and barnyardgrass were decreased, while their net assimilation rate increased. When the ratio of planting density of rice and barnyardgrass was 1:1, all of the ratio of biomass, yield, leaf area index, tiller and net assimilation rate were increased under FACE condition. It indicated that the competition between rice and barnyardgrass changed under FACE condition. The competition ability of rice(C3 crop) was enhanced relatively, while that of barnyardgrass weakened.

Carbon Dioxide↗