Implications of fossil fuel constraints on economic growth and global warming

Energy Security and Global Warming are analysed as 21st century sustainability threats.     

Resonance transformer power conditioners

One solution to the problem of high-power transformers is the concept of the resonance transformer, which uses a set of resonant circuits, made up of discrete inductors and capacitors, to achieve a transformerlike voltage gain. A brief overview of the general approach is presented. Because this approach does not require the magnetic core material associated with a conventional transformer, a significant savings in both size and weight can be realized, particularly at higher power levels. Technical issues associated with the conventional transformer, such as coupling of the primary and secondary windings at both high voltages and high frequencies and thermal management of heat generated in the transformer core, are also avoided. Several designs have been generated and tested, including a 20-kHz, 10- to 15-kW average power system. This power supply provides a voltage gain of 50 and weighs less than 45 kg. Additional designs for higher power levels above 1 MW are discussed along with information on expected sizes, weights, and general scaling tendencies     

Isolation of the third capsule-associated gene, CAP60, required for virulence in Cryptococcus neoformans

A polysaccharide capsule is one of the most important virulence factors for the pathogenic fungus Cryptococcus neoformans. We previously characterized two capsule-associated genes, CAP59 and CAP64. To further dissect the molecular mechanism of capsule synthesis, 16 acapsular mutants induced by 4-nitroquinoline-1-oxide were obtained. The acapsular phenotype of one of these mutants was complemented. The cloned gene was designated CAP60, and deletion of this newly described capsule-associated gene resulted in an acapsular phenotype. The proposed 67-kDa Cap60p contains 592 amino acids and appears to have a putative transmembrane domain close to the N terminus. DNA sequence analysis revealed that CAP60 has similarity to CAP59 at the center portion of its coding regions. Contour-clamped homogeneous electric field blot analysis suggested that these two genes are on the same chromosome. CAP60 and CAP59, however, could not be functionally substituted for each other by direct complementation or by domain swap experiments. In addition, CAP60 is closely linked to a gene which is similar to a cellulose growth-specific gene of Agaricus bisporus, CEL1. Immunogold electron microscopy studies of the epitope-tagged CAP60 gene revealed that Cap60p was primarily localized to the nuclear membrane. Animal model studies indicated that CAP60 is essential for virulence. Thus, CAP60 is required for both capsule formation and virulence.     

Identification of residues in the cysteine-rich domain of Raf-1 that control Ras binding and Raf-1 activity

We have identified mutations in Raf-1 that increase binding to Ras. The mutations were identified making use of three mutant forms of Ras that have reduced Raf-1 binding (Winkler, D. G., Johnson, J. C., Cooper, J. A., and Vojtek, A. B. (1997) J. Biol. Chem. 272, 24402-24409). One mutation in Raf-1, N64L, suppresses the Ras mutant R41Q but not other Ras mutants, suggesting that this mutation structurally complements the Ras R41Q mutation. Missense substitutions of residues 143 and 144 in the Raf-1 cysteine-rich domain were isolated multiple times. These Raf-1 mutants, R143Q, R143W, and K144E, were general suppressors of three different Ras mutants and had increased interaction with non-mutant Ras. Each was slightly activated relative to wild-type Raf-1 in a transformation assay. In addition, two mutants, R143W and K144E, were active when tested for induction of germinal vesicle breakdown in Xenopus oocytes. Interestingly, all three cysteine-rich domain mutations reduced the ability of the Raf-1 N-terminal regulatory region to inhibit Xenopus oocyte germinal vesicle breakdown induced by the C-terminal catalytic region of Raf-1. We propose that a direct or indirect regulatory interaction between the N- and C-terminal regions of Raf-1 is reduced by the R143W, R143Q, and K144E mutations, thereby increasing access to the Ras-binding regions of Raf-1 and increasing Raf-1 activity.