Dynamic wavelength control of laser pulse profiles at picosecond to nanosecond timescales.

We report on a novel combined laser pulse shaping and dynamic wavelength encoding capability based on a simple architecture implementing direct space to time mapping. There are several potential applications that can be enabled by the ability to control the instantaneous intensity or wavelength of an optical waveform on a picosecond-to-nanosecond timescale. To our knowledge, no known methods can access this temporal regime with a practical architecture. Here, we demonstrate an extension of the Space-Time Induced Linearly Encoded Transcription for Temporal Optimization (STILETTO) technique that can generate optical waveforms with a programmable instantaneous wavelength vs. time. We experimentally demonstrate the technique by generating self-gated spectrograms and show that it can encode dynamic wavelength vs time profiles at timescales not achievable by any other known method.

Governance and the loss of biodiversity.

Most of the world's biodiversity occurs within developing countries that require donor support to build their conservation capacity. Unfortunately, some of these countries experience high levels of political corruption, which may limit the success of conservation projects by reducing effective funding levels and distorting priorities. We investigated whether changes in three well surveyed and widespread components of biodiversity were associated with national governance scores and other socio-economic measures. Here we show that governance scores were correlated with changes in total forest cover, but not with changes in natural forest cover. We found strong associations between governance scores and changes in the numbers of African elephants and black rhinoceroses, and these socio-economic factors explained observed patterns better than any others. Finally, we show that countries rich in species and identified as containing priority areas for conservation have lower governance scores than other nations. These results stress the need for conservationists to develop and implement policies that reduce the effects of political corruption and, in this regard, we question the universal applicability of an influential approach to conservation that seeks to ban international trade in endangered species.

Nitroimidazoles with antibacterial activity against Neisseria gonorrhoeae.

Nitroimidazoles have been prepared which show interesting activity against the bacterium, Neisseria gonorrhoeae, in addition to the activities usually shown by nitroimidazoles against protozoa and anaerobic bacteria. The compounds were prepared by alkylation of 1-methyl-2-mercaptoimidazole, followed by nitration. Optimum activity occurs with a 5-nitro group and a free carboxyl at the end of the group attached to the sulfur. The linkage between the sulfur atom and the carboxyl group can be alkylene or phenoxyalkylene. These compounds have only weak activity against other aerobic or facultative bacteria.

Microbial degradation of sterols.

A process is described for the microbial degradation of cholesterol and plant sterols, to produce androsta-1, 4-diene-3, 17-dione and androst-4-ene-3, 17-dione, by two newly isolated bacteria designated Mycobacterium sp. NRRL B-3683 and Mycobacterium sp. NRRL B-3805. These myocbacteria produce substantial amounts of 17-ketonic compounds without appreciable degradation of the steroid nucleus. No ring degradation inhibitory agents are necessary. The first microbiological production of 20alpha-hydroxymethylpregna-1, 4-dien-3-one is also reported.