Indigenous rice production and the subtleties of culture change: An example from Borneo

This analysis is based on a combination of participant observation, census data, and an agricultural survey in two Kenyah Dayak communities in East Kalimantan: isolated Long Ampung, and “modernizing” Long Segar. The dramatically higher rice yields per household in the more “modern” community are first investigated, from indigenous and “scientific” points of view. Demographic and yield data are then used to demonstrate a) a decrease in women's contribution to rice production in Long Segar compared to men, and b) an emerging conflict between production and care of dependents. Both trends point to a decrease in women's status in Long Segar. Suggestions are then offered on possible interventions that could reduce such negative impacts of agricultural development on farm families, without adversely affecting yields.     

Carbon and nitrogen isotopic anomalies in an anhydrous interplanetary dust particle

Because hydrogen and nitrogen isotopic anomalies in interplanetary dust particles have been associated with carbonaceous material, the lack of similar anomalies in carbon has been a major conundrum. We report here the presence of a 13C depletion associated with a 15N enrichment in an anhydrous interplanetary dust particle. Our observations suggest that the anomalies are carried by heteroatomic organic compounds. Theoretical models indicate that low-temperature formation of organic compounds in cold interstellar molecular clouds can produce carbon and nitrogen fractionations, but it remains to be seen whether the specific effects observed here can be reproduced.     

Rotary photon drag enhanced by a slow-light medium

Transmission through a spinning window slightly rotates the polarization of the light, typically by a microradian. It has been predicted that the same mechanism should also rotate an image. Because this rotary photon drag has a contribution that is inversely proportional to the group velocity, the image rotation is expected to increase in a slow-light medium. Using a ruby window under conditions for coherent population oscillations, we induced an effective group index of about 1 million. The resulting rotation angle was large enough to be observed by the eye. This result shows that rotary photon drag applies to images as well as polarization. The possibility of switching between different rotation states may offer new opportunities for controlled image coding.     

Identification of active gold nanoclusters on iron oxide supports for CO oxidation

Gold nanocrystals absorbed on metal oxides have exceptional properties in oxidation catalysis, including the oxidation of carbon monoxide at ambient temperatures, but the identification of the active catalytic gold species among the many present on real catalysts is challenging. We have used aberration-corrected scanning transmission electron microscopy to analyze several iron oxide-supported catalyst samples, ranging from those with little or no activity to others with high activities. High catalytic activity for carbon monoxide oxidation is correlated with the presence of bilayer clusters that are approximately 0.5 nanometer in diameter and contain only approximately 10 gold atoms. The activity of these bilayer clusters is consistent with that demonstrated previously with the use of model catalyst systems.     

Sea Surface Temperature, Surface Wind Divergence, and Convection over Tropical Oceans

Large-scale convection over the warm tropical oceans provides an important portion of the driving energy for the general circulation of the atmosphere. Analysis of regional associations between ocean temperature, surface wind divergence, and convection produced two important results. First, over broad regions of the Indian and Pacific oceans, sea surface temperatures (SSTs) in excess of 27.5 degrees C are required for large-scale deep convection to occur. However, SSTs above that temperature are not a sufficient condition for convection and further increases in SST appear to have little effect on the intensity of convection. Second, when SSTs are above 27.5 degrees C, surface wind divergence is closely associated with the presence or absence of deep convection. Although this result could have been expected, it was also found that areas of persistent divergent surface flow coincide with regions where convection appears to be consistently suppressed even when SSTs are above 27.5 degrees C. Thus changes in atmospheric stability caused by remotely forced changes in subsidence aloft may play a major role in regulating convection over warm tropical oceans.     

Characterization and evaluation of North American Trifolium ambiguum -nodulating rhizobia

Kura clover ( Trifolium ambiguum M. Bieb.) is a promising persistent forage legume, whose use is currently limited by establishment difficulties in part attributable to nodulation problems. In this study, we phenotypically characterized 18 Kura clover rhizobia including 12 newly isolated North American strains using 111 growth tests. The symbiotic performances of these 12 strains when used to inoculate hexaploid Kura clover plants were then evaluated in a growth chamber and compared to five strains commonly used in commercial Kura clover inoculants. Non-inoculated plants with or without N fertilization were used as controls. Field evaluations were also conducted in 2001 and 2002 in Montreal, Quebec and Becker, Minnesota. Hexaploid Kura clover was seeded with one of three North American strains or three commercial strains and compared to non-inoculated controls with or without N fertilizer. Phenotypic diversity observed among the 12 North American strains was limited. The North American strains were often more efficient than strains commonly used in commercial rhizobial inoculants in both growth chamber and field trials. In the growth chamber study, 60 days after seeding, shoot dry matter accumulation was overall 205% greater with North American strains than with commercial strains and 45% greater than with the best commercial strain tested. Some of the strains currently used in commercial inoculants failed to nodulate Kura clover plants effectively. North American strains tested in field trials (i.e., CT1-1, CT1-2, and WI4-4) overall increased total and shoot dry matter accumulation, 100 days after seeding, in three of four environments by 27% and 31% respectively, when compared to commercial inoculant strains. While these strains appear to have potential they still produced less dry matter than non-inoculated N-fertilized controls.