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<jats:p>Analysis of Vendian to Cambrian paleomagnetic data shows anomalously fast rotations and latitudinal drift for all of the major continents. These motions are consistent with an Early to Middle Cambrian inertial interchange true polar wander event, during which Earth's lithosphere and mantle rotated about 90 degrees in response to an unstable distribution of the planet's moment of inertia. The proposed event produces a longitudinally constrained Cambrian paleogeography and accounts for rapid rates of continental motion during that time.</jats:p>

<jats:p> The synthesis of and magneto-transport in the “colossal magnetoresistance” (CMR) pyrochlore-structure compounds Tl <jats:sub>2</jats:sub> <jats:sub>−</jats:sub> <jats:sub> <jats:italic>x</jats:italic> </jats:sub> Sc <jats:sub> <jats:italic>x</jats:italic> </jats:sub> Mn <jats:sub>2</jats:sub> O <jats:sub>7</jats:sub> for 0 ≤ <jats:italic>x</jats:italic> ≤ 0.5 are reported. The maximum resistivity (ρ) increases by 10 <jats:sup>5</jats:sup> while the Curie temperature ( <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> ) decreases by only 25% between <jats:italic>x</jats:italic> = 0 and 0.4. For <jats:italic>x</jats:italic> = 0.2 to 0.3, the magnetoresistance at both high field (6 tesla) and low field (&lt;0.05 tesla) are significantly enhanced over the undoped ( <jats:italic>x</jats:italic> = 0) compound. Structural analysis indicates that all of the manganese ions are near the +4 oxidation state. The behavior of ρ and <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> suggests that scandium substitution affects mainly electronic conduction on the thallium-oxygen sublattice while leaving the magnetism essentially unchanged. These results demonstrate a distinct way of manipulating magneto-transport properties in CMR materials. </jats:p>

<jats:p>Optical processing with photorefractive polymers depends on achieving high optical gain, which depends exponentially on the product of the interaction length and the gain coefficient. By use of several polymer layers to increase the overall interaction length and a new high-performance photorefractive polymer composite, the overall optical one-pass gain becomes as large as a factor of 5. For a two-layer sample placed in an optical cavity made with two concave mirrors, spontaneous oscillation due to two-beam coupling gain was observed. Because only one pumping beam is required, this configuration also acts as a self-pumped phase-conjugating mirror with a reflectivity of 13 percent for an applied electric field of 75 volts per micrometer, marking a milestone for this growing class of optoelectronic materials.</jats:p>

<jats:p> The lyotropic <jats:italic>L</jats:italic> <jats:sub>3</jats:sub> phase was used as a template to form nanoporous monolithic silicates with continuously adjustable pore sizes. The monolith was optically isotropic and transparent with a nonperiodic network. The pore size was adjusted by a change in the solvent volume fraction rather than by a change of the surfactant. Unlike other silicates, the bicontinuous pores were water-filled; removal of surfactant was not necessary to access the pores. Measured characteristic dimensions were from six to more than 35 nanometers. For a given solvent fraction, x-ray scattering indicated little variation of pore widths, in marked contrast to the polydisperse pores of aerogels. </jats:p>

<jats:p>Transport of membrane proteins between intracellular compartments requires specific sequences in the protein cytoplasmic domain to direct packaging into vesicle shuttles. A sequence that mediates export from the endoplasmic reticulum (ER) has proved elusive. A di-acidic signal (Asp-X-Glu, where X represents any amino acid) on the cytoplasmic tail of vesicular stomatitis virus glycoprotein (VSV-G) and other cargo molecules was required for efficient recruitment to vesicles mediating export from the ER in baby hamster kidney cells. The existence of such a signal provides evidence that export from the ER occurs through a selective mechanism.</jats:p>

<jats:p> Mutations in the gene encoding copper/zinc superoxide dismutase enzyme produce an animal model of familial amyotrophic lateral sclerosis (FALS), a fatal disorder characterized by paralysis. Overexpression of the proto-oncogene <jats:italic>bcl-2</jats:italic> delayed onset of motor neuron disease and prolonged survival in transgenic mice expressing the FALS-linked mutation in which glycine is substituted by alanine at position 93. It did not, however, alter the duration of the disease. Overexpression of <jats:italic>bcl-2</jats:italic> also attenuated the magnitude of spinal cord motor neuron degeneration in the FALS-transgenic mice. </jats:p>

<jats:p> C-peptide, a cleavage product from the processing of proinsulin to insulin, has been considered to possess little if any biological activity other than its participation in insulin synthesis. Injection of human C-peptide prevented or attenuated vascular and neural (electrophysiological) dysfunction and impaired Na <jats:sup>+</jats:sup> - and K <jats:sup>+</jats:sup> -dependent adenosine triphosphate activity in tissues of diabetic rats. Nonpolar amino acids in the midportion of the peptide were required for these biological effects. Synthetic reverse sequence (retro) and all– <jats:sc>d</jats:sc> –amino acid (enantio) C-peptides were equipotent to native C-peptide, which indicates that the effects of C-peptide on diabetic vascular and neural dysfunction were mediated by nonchiral interactions instead of stereospecific receptors or binding sites. </jats:p>

<jats:p> Protein kinase B (PKB) is a proto-oncogene that is activated in signaling pathways initiated by phosphoinositide 3-kinase. Chromatographic separation of brain cytosol revealed a kinase activity that phosphorylated and activated PKB only in the presence of phosphatidylinositol-3,4,5-trisphosphate [PtdIns(3,4,5)P <jats:sub>3</jats:sub> ]. Phosphorylation occurred exclusively on threonine-308, a residue implicated in activation of PKB in vivo. PtdIns(3,4,5)P <jats:sub>3</jats:sub> was determined to have a dual role: Its binding to the pleckstrin homology domain of PKB was required to allow phosphorylation by the upstream kinase and it directly activated the upstream kinase. </jats:p>

<jats:p>More than 1% of the world's population is chronically infected with hepatitis C virus (HCV). HCV infection can result in acute hepatitis, chronic hepatitis, and cirrhosis, which is strongly associated with development of hepatocellular carcinoma. Genetic studies of HCV replication have been hampered by lack of a bona fide infectious molecular clone. Full-length functional clones of HCV complementary DNA were constructed. RNA transcripts from the clones were found to be infectious and to cause disease in chimpanzees after direct intrahepatic inoculation. This work defines the structure of a functional HCV genome RNA and proves that HCV alone is sufficient to cause disease.</jats:p>

<jats:p> Chromosome movements and spindle dynamics were visualized in living cells of the budding yeast <jats:italic>Saccharomyces cerevisiae</jats:italic> . Individual chromosomal loci were detected by expression of a protein fusion between green fluorescent protein (GFP) and the Lac repressor, which bound to an array of Lac operator binding sites integrated into the chromosome. Spindle microtubules were detected by expression of a protein fusion between GFP and Tub1, the major alpha tubulin. Spindle elongation and chromosome separation exhibited biphasic kinetics, and centromeres separated before telomeres. Budding yeast did not exhibit a conventional metaphase chromosome alignment but did show anaphase A, movement of the chromosomes to the poles. </jats:p>