Isolation and DNA sequence of the STE14 gene encoding farnesyl cysteine: Carboxyl methyltransferase

We isolated a mutant defective in C-terminal farnesyl cysteine:carboxyl methyltransferase activity from a screen for mutations causing a -specific sterility. A genomic fragment was cloned from a yeast multi-copy library that restored mating. Both the cloned gene and the sterile mutation were allelic to the STE14 gene. A ste14-complementing 2·17 kb BamHI fragment subclone was sequenced and found to encode a 239 amino acid protein with a molecular weight of 27,887 Daltons. The hydrophobicity profile of the methyltransferase reveals the presence of at least five potential transmembrane domains. In comparisons of the C-terminal methyltransferase amino acid sequence with those in the PIR and Swiss protein databases, no significantly similar sequences were found nor were conserved regions from other methyltransferases present.     

Lipopolysaccharide-stimulated osteoclastogenesis is mediated by tumor necrosis factor via its P55 receptor

Chronic bone infection, as attends periodontitis, is often complicated by severe osteolysis. While LPS is believed to be central to the pathogenesis of the osteolytic lesion, the mechanisms by which this bacteria-derived molecule promotes bone resorption are unknown. We find that LPS induces bone marrow macrophages (BMMs) to express c-src, a protooncogene product that we demonstrate is a specific marker of commitment to the osteoclast phenotype. We next turned to possible soluble mediators of LPS-induced c-src. Of a number of osteoclastogenic cytokines tested, only TNF-alpha mirrors the c-src-enhancing effect of LPS. Suggesting that LPS augmentation of c-src is TNF-mediated, endotoxin sequentially induces BMM expression of TNF, followed by c-src. TNF and c-src expression, by cultured BMMs derived from LPS-injected mice, reflects duration of exposure to circulating endotoxin, intimating that endotoxin's effect in vivo is also mediated by TNF. Consistent with these findings, thalidomide (which antagonizes TNF action) attenuates c-src induction by LPS. An anti-TNF antibody blocks LPS enhancement of c-src mRNA, validating the cytokine's modulating role in vitro. Using BMMs of TNF receptor-deleted mice, we demonstrate that TNF induction of c-src is transmitted through the cytokine's p55, but not p75, receptor. Most importantly, LPS administered to wild-type mice prompts osteoclast precursor differentiation, manifest by profound osteoclastogenesis in marrow cultured ex vivo, and by a profusion of marrow-residing cells expressing the osteoclast marker tartrate resistant acid phosphatase, in vivo. In contrast, LPS does not substantially enhance osteoclast proliferation in mice lacking the p55TNF receptor, confirming that LPS-induced osteoclastogenesis is mediated by TNF in vivo via this receptor. Thus, therapy targeting TNF and/or its p55 receptor presents itself as a means of preventing the osteolysis of chronic bacterial infection.     

Complexity theory of parallel time and hardware

The parallel resources time and hardware and the complexity classes defined by them are studied using the aggregate model. The equivalence of complexity classes defined by sequential space and uniform aggregate hardware is established. Aggregate time is related to (bounded fanin) circuit depth and, similarly, aggregate hardware is related to circuit width. Interelationships between aggregate time and hardware follow as corollaries. Aggregate time is related to the sequential resource reversal. Simultaneous relationships from aggregate hardware and time to sequential space and reversal are shown (and conversely), and these are used as evidence for an “extended parallel computation thesis.” These simultaneous relationships provide new characterizations for the simultaneous parallel complexity class NC and for the complementary class SC. The evaluation of monotone planar circuits is shown to be in NC, in fact in LOGCFL.     

Multiconfiguration Dirac-Fock wavelengths and transition rates in the X-ray spectra of highly charged Ga-like ions from Yb to U

A multiconfiguration Dirac-Fock (MCDF) technique has been used for computing the wavelengths and transition probabilities for lines in the X-ray spectra of the gallium-like ions from Yb XL to U LXII. Results are presented for the 4s²4p-4s²4d and 4s²4p-4s4p² allowed transitions (E1) as well as for the forbidden transitions (M1 and E2) within the ground configuration 4s²4p. A comparison of the calculated wavelengths with the few experimental results available is also presented.     

Using airborne laser scanning to monitor tree migration in the boreal-alpine transition zone

The boreal tree line is expected to advance upwards into the mountains and northwards into the tundra due to global warming. The major objective of this study was to find out if it is possible to use high-resolution airborne laser scanner data to detect very small trees — the pioneers that are pushing the tree line up into the mountains and out onto the tundra. The study was conducted in a sub-alpine/alpine environment in southeast Norway. A total of 342 small trees of Norway spruce, Scots pine, and downy birch with tree heights ranging from 0.11 to 5.20 m were precisely georeferenced and measured in field. Laser data were collected with a pulse density of 7.7 m^− 2. Three different terrain models were used to process the airborne laser point cloud in order to assess the effects of different pre-processing parameters on small tree detection. Greater than 91% of all trees > 1 m tall registered positive laser height values regardless of terrain model. For smaller trees (< 1 m), positive height values were found in 5-73% of the cases, depending on the terrain model considered. For this group of trees, the highest rate of trees with positive height values was found for spruce. The more smoothed the terrain model was, the larger the portion of the trees that had positive laser height values. The accuracy of tree height derived from the laser data indicated a systematic underestimation of true tree height by 0.40 to 1.01 m. The standard deviation for the differences between laser-derived and field-measured tree heights was 0.11-0.73 m. Commission errors, i.e., the detection of terrain objects — rocks, hummocks — as trees, increased significantly as terrain smoothing increased. Thus, if no classification of objects into classes like small trees and terrain objects is possible, many non-tree objects with a positive height value cannot be separated from those actually being trees. In a monitoring context, i.e., repeated measurements over time, we argue that most other objects like terrain structures, rocks, and hummocks will remain stable over time while the trees will change as they grow and new trees are established. Thus, this study indicates that, given a high laser pulse density and a certain density of newly established trees, it would be possible to detect a sufficient portion of newly established trees over a 10 years period to claim that tree migration is taking place.     

Theoretical analysis of a fractal surface radiation

We compare, in this paper, the far field radiated by two fractal distributions of current. The first one is obtained by a fractal cut following the Cantor arrangement, the second one keeps the length of each previous current element, but modifies the distance between the elements which is now taken as a constant. We establish the analytical formulations of the far field at any step n of the Cantor set. Then, we extract the array factor and we analyse and compare the following properties : convergence of the radiation pattern, wide of the main lobe, side lobes level and directivity.     

Toward functional magnetic stimulation (FMS) theory and experiment

Examines the use of magnetic fields to functionally stimulate peripheral nerves. All electric fields are induced via a changing magnetic field whose flux is entirely confined within a closed magnetic circuit. Induced electric fields are simulated using a nonlinear boundary element solver. The induced fields are solved using duality theory. The accuracy of these predictions is verified by saline bath experiments. Next, the theory is applied to the stimulation of nerves using small, partially occluded ferrite and laminated vanadium permendur cores. Experiments demonstrate the successful stimulation of peripheral nerves in the African bullfrog with 11 mA, 153 mV excitations. These results offer a new vista of possibilities in the area of functional nerve stimulation. Unlike functional electric stimulation (FES), FMS does not involve any half cell reactions, and thus would not have the commensurate FES restrictions regarding balanced biphasic stimulation, strength duration balances, and oxidation issues, always exercising care that the electrodes remain in the reversible operating regime