Metabolic engineering to produce sesquiterpenes in yeast

[reaction: see text] Presented here is a metabolically engineered yeast strain that produces sesquiterpenes. Epi-cedrol synthase expressed in a native yeast strain converted endogenous farnesyl pyrophosphate to 90 microg/L epi-cedrol. This system was genetically modified to increase foreign terpene yields to 370 microg/L. The best yields were obtained by overexpressing a truncated 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase in a upc2-1 mating type a background. This system allows sufficient production to characterize novel sesquiterpene synthase genes.     

Boundary Effects on Exact Solutions of the Lagrangian-Averaged Navier–Stokes-α Equations

In order to clarify the behavior of solutions of the Lagrangian-averaged Navier–Stokes- (LANS-) equations in the presence of solid walls, we identify a variety of exact solutions of the full equations and their boundary layer approximations. The solutions demonstrate that boundary conditions suggested for the LANS- equations in the literature⁽¹⁾ for a bounded domain do not apply in a semi-infinite domain. The convergence to solutions of the Navier–Stokes equations as 0 is elucidated for infinite-energy solutions in a semi-infinite domain, and non-uniqueness of these solutions is discussed. We also study the boundary layer approximation of LANS- equations, denoted the Prandtl- equations, and report solutions for turbulent jets and wakes. Our version of the Prandtl- equations includes an extra term necessary to conserve linear momentum and corrects an earlier result of Cheskidov.⁽²⁾     

Generalized Hardy inequalities

We show that the generalized Hardy inequality holds for f∈H₁ and certain (b_k)∈l_r (2?q?∞) whenever satisfies appropriate growth conditions dependent on r.     

Crystal growth and conductivity investigations on BiVO4 single crystals

Some oxides with the scheelite structure are well known mixed ionic and electronic conductors. This structure family, with the general composition ABO₄, can be described as a layer structure derivative of the fluorite structure. The relations between the structural and the electrical transport properties of these materials have been investigated. The model system used in this work was BiVO₄, which shows both electronic and ionic conduction. Single crystals of bismuth vanadate (BiVO₄) were grown using the Czochralski technique. Single crystal boules up to 55 mm in diameter and up to 30 mm long were produced. The crystallographic orientation was determined by the Laue method, and they were cleaved along [001] planes and polished to optically perfect cubes with an edge length of 5 mm. Two-point ac impedance measurements in the temperature range between 550°C and 700°C were performed. The conductivities were measured as a function of the crystal orientation and showed strong anisotropy as expected from the crystal structure. Paper presented at the 2nd Euroconference on Solid State Ionics, Funchal, Madeira, Portugal, Sept. 10–16, 1995     

Calculation of motional activation energies for interstitial ions in the rutile structure using a minimum energy path model

Motional activation enthalpies have been calculated for interstitial cations in the rutile structure, using a minimum energy path approach. Coulombic, overlap repulsion and polarization energy terms were included in the potential energy expression. Preexponential factors in the overlap repulsion terms were evaluated by minimizing of the total electrostatic energy, and permanent dipole moments of the anion by an iterative method. The most favorable diffusion path was found to be parallel to the c-axis in the $\text{1}\text{2}$, 0, z direction in both TiO₂ and MgF₂.Motional activation enthalpies increased with increasing interstitial cation radius and were larger in TiO₂ than in MgF₂. The path was independent of radius and material. Strongly anisotropic conductivity was predicted for both compounds.     

THE EFFECT OF DIFFERENT TYPES OF FLUORESCENT LIGHTING ON REPRODUCTION AND TUMOR DEVELOPMENT IN THE C3H MOUSE

Abstract— The effect of three different fluorescent lighting systems on the growth, reproduction, and lifespan of the C₃H/HeN(MTV) mouse has been investigated. The mice were born, weaned, and paired under luminaires containing daylight-simulating (DS; 425 μW/cm²), cool-white (CW; 425μW/cm²) or pink (PK; 234 μW/cm²) fluorescent lights. At the end of the study (19 months), 97% of the females in the DS and CW groups and 100% of females in the PK group had developed mammary tumors. The median times for mammary tumor development were 51 weeks (DS), 47 weeks (CW) and 42 weeks (PK) The median age of the dam at first litter and the median time between the first and second litters were not significantly different for the three lighting conditions. However, there was some evidence that the first litter was significantly delayed in both the CW and PK groups compared to the DS group. There were no significant differences in the total number of litters/dam, the total number of pups/dam, the neonatal mortality of the pups (at birth or weaning), the weights of the pups at weaning or the sex ratios among the three lighting groups. The growth of the male mice was the same under all three lighting conditions. The observed differences in tumor latency and reproduction, between female mice exposed to the DS and CW fluorescent lights, may be related to the different spectral energy distributions of these lighting systems since their irradiances were the same.     

Identifying authority structures in mathematics classroom discourse: a case of a teacher’s early experience in a new context

We explore a conceptual frame for analyzing mathematics classroom discourse to understand the way authority is at work. This case study of a teacher moving from a school where he is known to a new setting offers us the opportunity to explore the use of the conceptual frame as a tool for understanding how language practice and authority relate in a mathematics classroom. This case study illuminates the challenges of establishing disciplinary authority in a new context while also developing the students’ sense of authority within the discipline. To analyze the communication in the teacher’s grade 12 class in the first school and grade 9 class early in the year at the new school, we use the four categories of positioning drawn from our earlier analysis of pervasive language patterns in mathematics classrooms—personal authority, discourse as authority, discursive inevitability, and personal latitude.     

“Mathematicians Would Say It This Way”: An Investigation of Teachers' Framings of Mathematicians

Although popular media often provides negative images of mathematicians, we contend that mathematics classroom practices can also contribute to students' images of mathematicians. In this study, we examined eight mathematics teachers' framings of mathematicians in their classrooms. Here, we analyze classroom observations to explore some of the characteristics of the teachers' framings of mathematicians in their classrooms. The findings suggest that there may be a relationship between a teachers' mathematics background and his/her references to mathematicians. We also argue that teachers need to be reflective about how they represent mathematicians to their students, and that preservice teachers should explore their beliefs about what mathematicians actually do.