Evolution of Science Popularization Policy in China

The government has considered science popularization as an issue of great importance since the founding of the People’s Republic of China. Many policies and regulations on science popularization were promulgated in the past 60 years, which had major influence upon various sectors of the society. In this chapter, based on about 1000 policy literatures in relation to science popularization, all the papers would be sorted using certain criteria and 100 most valuable would be selected. Secondly, to understand culture in the policy domain better, the paper will further focus on the background and aim of policy making, the underpinning ideology, as well as the efficacy. This study will reflect on historical evolution of policy and what the policy drive has produced

Novel Nonlinear Optics and Quantum Optics Approaches for Ultrasound-Modulated Optical Tomography in Soft Biological Tissue

Optical imaging of soft biological tissue is highly desirable since it is nonionizing and provides sensitive contrast information which enables the detection of physiological functions and abnormalities, including potentially early cancer detection. However, due to the diffusive nature of light in soft biological tissue, it is difficult to achieve simultaneously good spatial resolution and good imaging depth with pure optical imaging modalities. This work focuses on the ultrasound-modulated optical tomography (UOT): a hybrid technique which combines the advantages of ultrasonic resolution and optical contrast. In this technique, focused ultrasound and optical radiation of high temporal coherence are simultaneously applied to soft biological tissue. The intensity of the sideband, or ultrasound ‗tagged‘ photons depends on the optical absorption in the region of interest where the ultrasound is focused. Demodulation of the optical speckle pattern yields the intensity of tagged photons for each location of the ultrasonic focal spot. Thus UOT yields an image with spatial resolution of the focused ultrasound — typically submillimeter — whose contrast is related to local optical absorption and the diffusive properties of light in the organ. Thus it extends all the advantages of optical imaging deep into highly scattering tissue. However lack of efficient tagged light detection techniques has so far prevented ultrasound-modulated optical tomography from achieving maturity. The signal-to-noise ratio (SNR) and imaging speed are two of the most important figures of merit and need further improvement for UOT to become widely applicable. In the first part of this work, nonlinear optics detection methods have been implemented to demodulate the ―tagged‖ photons. The most common of these is photorefractive (PR) two wave mixing (TWM) interferometry, which is a time-domain filtering technique. When used for UOT, it is found that this approach extracts not only optical properties but also mechanical properties for the area of interest. To improve on TWM, PR four wave mixing (FWM) experiments were performed to read out only the modulated light and at the same time strongly suppressing the ‗untagged‘ light. Spectral-hole burning (SHB) in a rare-earth-ion-doped crystal has been developed for UOT more recently. Experiments in Tm3 :Y3Al5O12 (Tm:YAG) show the outstanding features of SHB: large angle acceptance (etendue), light speckle processing in parallel (insensitive to the diffusive light nature) and real-time signal collection (immune to light speckle decorrelation). With the help of advanced laser stabilization techniques, two orders of magnitude improvement of SNR have been achieved in a persistent SHB material (Pr^3 :Y2SiO5) compared to Tm:YAG. Also slow light with PSHB further reduces noise in Pr:YSO UOT that is caused by polarization leakage by performing time-domain filtering

The Responses of the Quantitative Characteristics of a Ramet Population of the Ephemeroid Rhizomatous Sedge Carex physodes

In this study, the soil moisture content was measured, and the quantitative characteristics of this sedge species were compared. The phenotypic plasticity of each parameter and the linear regression relationships were analyzed. The results showed that the soil moisture content was significantly affected by location, soil depth, and sampling date. The aboveground biomass, underground biomass, biomass density, and population density at the peak were significantly higher than elsewhere on the dune. However, the morphological plasticity index of the quantitative characteristics was higher at the base and middle of the dune. When the soil moisture content decreased, the underground biomass and ramet biomass density increased. The aboveground and underground biomasses were strongly negatively correlated, but the ramet height and aboveground biomass were strongly positively correlated. These results indicated that the soil water content significantly affected the clonal growth of C. physodes. The responsiveness of C. physodes may be adaptive when the soil resource supply is low. The strong morphological plasticity of the species appears to be ecologically important for the maintenance and dominance of this species in the dune habitat

Seed Dormancy-Breaking in a Cold Desert Shrub in Relation to Sand Temperature and Moisture

Seasonal periodicity of seed germination and its relationship to seasonal changes in temperature and soil moisture have been well studied in seeds of species with physiological dormancy. However, relatively little information is available on the role of these environmental factors in controlling germination of seeds with physical dormancy (PY). Our primary aim was to determine if seeds of the cold desert sand dune semi-shrub Eremosparton songoricum exhibits seasonal periodicity of seed germination and the relationship between seed dormancy break and soil temperature and moisture. In the laboratory, seeds incubated on dry, wet, wet-dry and dry-wet sand were exposed to a 1-year sequence of temperature regimes simulating those in the field. In the field, seeds were buried at different depths on a sand dune, and germination of periodically exhumed seeds was tested at five temperature regimes during a 2-year period. In the one-year sequence of simulated natural temperature regimes, breaking of PY was more effective under constantly wet than under constantly dry conditions, and germination percentage was significantly higher under dry-wet than under wet-dry conditions. Seeds buried in the field exhibited a distinct peak of germination in spring and little or no germination in other seasons. The final (two-year) monthly cumulative germination percentage differed among burial depths and temperature, and it was highest (47%) in seeds buried at 3 cm and tested at 25/10 °C. A seed cohort of E. songoricum likely exhibits a long-term annual periodicity of spring germination in the field, and dormancy break appears to be driven by low (winter) temperatures and relatively high sand moisture content. To our knowledge this is the first study to document seasonal periodicity in seed germination in a cold desert species with PY and to identify the mechanism (at the whole-seed level) of its occurrence

Optical and mechanical properties in photorefractive crystal based ultrasound-modulated optical tomography

Ultrasound-modulated optical tomography (UOT) is a new technique that combines laser light and ultrasound to provide images with good optical contrast and good ultrasound resolution in soft biological tissue. We improve the method proposed by Murray et al to obtain UOT images in thick biological tissues with the use of photorefractive crystal based interferometers. It is found that a long ultrasound burst (on the order of a millisecond) can improve the signal-to-noise ratio dramatically. Also with a long ultrasound burst, the response of the acoustic radiation force impulses can be clearly observed in the UOT signal, which will help to acquire images that record both the optical and mechanical properties of biological soft tissues

Effects of Increased Precipitation on the Life History of Spring- and Autumn-Germinated Plants of the Cold Desert Annual \u3cem\u3eErodium oxyrhynchum\u3c/em\u3e (Geraniaceae)

Future increased precipitation in cold desert ecosystems may impact annual/ephemeral plant species that germinate in both spring and autumn. Our primary aim was to compare the life history characteristics of plants from spring-germinating (SG) and autumn-germinating (AG) seeds of Erodium oxyrhynchum. Plants in field plots with simulated increases in precipitation of 0, 30 and 50 % in spring and summer were monitored to determine seedling survival, phenology, plant size, seed production and biomass accumulation and allocation. Germination characteristics were determined in the laboratory for seeds produced by plants in all increased precipitation treatments. Increased precipitation in spring significantly improved survival of seedlings from SG and AG seeds, but survival was less for AG than SG. An increase in precipitation increased the number of seeds per plant for both SG and AG, but AG produced more seeds per plant than SG. With increased precipitation, percentage of dormant seeds from SG increased significantly, while that of AG decreased slightly. Our study suggests that with increased spring and summer rainfall AG will produce an increased number of nondormant seeds that could germinate in autumn and SG an increased number of dormant seeds that become part of the soil seed bank. However, ability of some seeds to germinate in autumn and others in spring will be maintained as long as soil moisture is limited in autumn

Ultrasound-modulated optical tomography using four-wave mixing in photorefractive polymers

Ultrasound-modulated optical tomography uses a well focused ultrasound beam to modulate diffuse light inside soft biological tissues. This modality combines the advantages of ultrasound resolution with optical contrast. However, because of the low ultrasound modulation efficiency, the large background of un-modulated photons gives a low signal-to-noise ratio. Here we report a technique for detection of ultrasound-modulated light using a phase conjugated signal generated by four-wave mixing in a photorefractive polymer. The experimental results demonstrate the potential of this method to detect ultrasound-modulated optical signals in a highly scattering media with an excellent signal-to-noise ratio