An absorption tube for the investigation of gases in the photographic infrared

An absorption cell of novel design is described, which combines the advantages of long path and relatively small volume

Effects of nacelle shape on drag and weight of a supersonic cruising aircraft

The quantitive relationship of cruise drag and nacelle shape was investigated for a representative advanced supersonic transport configuration. Nacelle shape parameters were systematically varied, and the effects of these variations on wave and friction drag were determined. The effects of changes in vehicle drag, propulsion weight, and specific fuel consumption on vehicle takeoff gross weight were computed. Generally, it was found that nacelle shapes such that the maximum cross-sectional area occurred at or near the nozzle exit resulted in the lowest wave drag. In fact, nacelle shapes were found that produce favorable interference effects (drag reduction) of such magnitude as to nearly offset the friction drag of the nacelle

Effects of post-translational modifications catalysed by pollen transglutaminase on the functional properties of microtubules and actin filaments

TGases (transglutaminases) are a class of calcium-dependent enzymes that catalyse the interactions between acyl acceptor glutamyl residues and amine donors, potentially making crosslinks between proteins. To assess the activity of apple (Malus domestica) pollen TGase on the functional properties of actin and tubulin, TGase was prepared from apple pollen by hydrophobic interaction chromatography and assayed on actin and tubulin purified from the same cell type. The enzyme catalysed the incorporation of putrescine in the cytoskeleton monomers. When tested on actin filaments, pollen TGase induced the formation of high-molecular-mass aggregates of actin. Use of fluorescein– cadaverine showed that the labelled polyamine was incorporated into actin by pollen TGase, similar to with guinea pig liver TGase. The pollen TGase also reduced the enzyme activity and the binding of myosin to TGase-treated actin filaments. Polymerization of tubulin in the presence of pollen TGase also yielded the formation of high molecular mass aggregates. Furthermore, the pollen TGase also affected the binding of kinesin to microtubules and reduced the motility of microtubules along kinesincoated slides. These results indicate that the pollen tube TGase can control different properties of the pollen tube cytoskeleton (including the ability of actin and tubulin to assemble and their interaction with motor proteins) and consequently regulate the development of pollen tubes

Evaluation of a putative entomopathogenic Caenorhabditis (Nematoda: Rhabditid) and associated Serratia (Proteobacteria: Enterobacteriaceae)

A major goal of modern biology is to extend our understanding of biological systems investigated in the laboratory to their ecological and evolutionary context. With extensive understanding of the function, development and genetics of C. elegans, exploring the link between this laboratory model and the environment in which this system evolved would be very interesting because very little is known about the natural history of this premier model organism. A new strain of Caenorhabditis briggsae (SoAf) with an associated bacterium, Serratia sp. SCBI, has been isolated from South Africa using common entomopathogenic nematode trapping methods. This study taxonomically identified and evaluated entomopathogenic behavior of C. briggsae SoAf and Serratia sp. SCBI. Hemocoelic injections of Serratia sp. SCBI demonstrated pathogenicity in insect larvae, Galleria mellonella. Caenorhabditis briggsae SoAf and other Caenorhabditis, including C. elegans , were capable of infection, growth and reproduction within the insect larvae in the presence of Serratia sp. SCBI. Identification of a putative entomopathogenic C. briggsae expands on our understanding of Caenorhabditis ecology and provides a framework for further investigation of entomopathogensis in other free-living nematodes

Investigating Teacher Use of Practice Tests for Formative Purposes

This paper describes an intensive professional development program focused on supporting teachers at high-need urban high schools in use of practice tests for formative assessment purposes. Teachers engaged in professional development while offering intensive summer school to students with histories of failure on state tests in science and mathematics. Specific skills that teachers developed included item analysis of practice tests, planning around assessment results, and providing feedback to students. The study used a quasi-experimental pretest/posttest design with an intervention and a comparison group, analysis of classroom artifacts, follow-up surveys, and long-term follow-up with teachers. Students in the summer programs experienced large gains in performance, and teachers reported more frequent and varied use of tests for formative purposes, even one-and-one-half years after the end of training

Black hole solutions in 2+1 dimensions

We give circularly symmetric solutions for null fluid collapse in 2+1-dimensional Einstein gravity with a cosmological constant. The fluid pressure $P$ and energy density $\rho$ are related by $P=k\rho$ $(k\le 1)$. The long time limit of the solutions are black holes whose horizon structures depend on the value of $k$. The $k=1$ solution is the Banados-Teitelboim-Zanelli black hole metric in the long time static limit, while the $k<1$ solutions give other, `hairy' black hole metrics in this limit.Comment: 8 pages, RevTeX (to appear in Phys. Rev. D) References to Mann and Ross, and Mann, Chan and Chan adde

Spin Gap of S=1/2 Heisenberg Model on Distorted Diamond Chain

We study the spin gap of the S=1/2 Heisenberg model on the distorted diamond chain, which is recently proposed to represent magnetic properties of Cu_3 Cl_6 (H_2 O)_2 2H_8 C_4 SO_2. This model is composed of stacked trimers and has three kinds of exchange interactions J_1, J_2 and J_3. Using the numerical diagonalization, we obtain a contour map of the spin gap in the J_2/J_1-J_3/J_1 plane. We argue possible values of the exchange constants based on the contour map and the observed value of the spin gap.Comment: 2 pages, 4 figure

The impact of space and space-related activities on a local economy. a case study of boulder, colorado. part ii- the income-product accounts

Total impact of space and space related activities on local economy of Boulder, Colorado - income-product account