Sex Ratio and Sexual Dimorphism in \u3ci\u3eFormica Exsectoides\u3c/i\u3e, the Allegheny Mound Ant (Hymenoptera: Formicidae)

We excavated 66 mounds from 6 populations of Formica exsectoides in Michigan jack pine, collecting sexual caste pupae for sex ratio estimates and measurement of dimorphism. Reproductive caste brood was present in only 37 ofthe 66 mounds, and presence of reproductive caste brood was associated with larger mound surface area. Females were heavier than males, but did not differ from males in energy density. Sexes did not differ in timing or rate of development. Sex ratio estimates based on individual mounds ranged from 1.0 (all male) to 0.08 (female·biased). Four of the six study populations were strongly male·biased, while sex ratio estimates for the remaining populations did not differ from equal investment. While this interpopulation variation may be caused by genetic factors, the equal investment populations were 10· cated in or near patches of clear·cut forest, suggesting that environmental impacts should be investigated

Developing an Unnatural Amino Acid-Specific Aminoacyl tRNA Synthetase

Unnatural Amino Acids (UAAs), amino acids not present in the human genetic code, have been synthesized to have a broad range of useful properties, in this case, as metal-binders which could have drug delivery applications. In order for the cell to place a UAA into the protein, two components, a unique aminoacyl tRNA synthetase and a corresponding tRNA must be present. If an amino acid is successfully charged to the tRNA, a stop codon is suppressed and a functional protein is built with the UAA at the mutation site. Such a tRNA molecule has previously been developed, as well as many synthetases specific to UAAs. In this work, the range of UAAs which can be incorporated into proteins using the E. coli’s own machinery is expanded by the development of a novel aminoacyl tRNA synthetase. By making a library of synthetase-coding plasmid variants and performing positive and negative screenings, the binding pocket of the synthetase can be modified for specificity to a UAA while not allowing the tRNA to be charged with a natural amino acid. In this work, we are attempting to evolve new tRNA synthetases for the incorporation of metal-binding amino acids by developing the plasmid library and a screening system to find synthetase variants meeting these criteria

A "water shell" model for the dielectric properties of hydrated silica-filled epoxy nano-composites

The electrical properties of epoxy resin have been studied as a function of hydration. The epoxy was studied in an un-filled state, filled with 40 µm SiO2 particles, and filled with 50 nm SiO2 particles. The relative humidity was controlled by saturated salt solutions at ambient temperatures from 298-353 K. Measurements were made using dielectric spectroscopy over the frequency range 10-3-105 Hz. The hydration isotherm (i.e. the mass uptake of water) was established by measuring the mass as a function of relative humidity (RH). It was found that the nanocomposites absorb up to 60% more water than the unfilled and micro-filled epoxies. Dielectric spectroscopy shows different conduction and quasi-DC behaviours at very low frequencies (<10-2 Hz) with activation energies dependent on the hydration and temperature. These observations have led to the development of a “water shell” model to explain this phenomenon

Periodic Reporting in a Continuous World: The Correlating Evolution of Technology and Financial Reporting

The evolution of technology has drastically altered what it means to be a reporting company in the eyes of the Securities and Exchange Commission. Technological development has also played a large role in the shifting trend from periodic reporting to continuous reporting, as is particularly apparent in the evolution of the Form 8-K. It is true that the increasingly technological world of continuous reporting does not come without disadvantages. This issue brief, however, argues that despite the increased risks and challenges of continuous reporting, its net effect on disclosure, and the investing community generally, is positive. With that benefit in mind, this paper further suggests four new amendments to the Form 8-K

The effect of water absorption on the dielectric properties of epoxy nanocomposites

In this research, the influence of water absorption on the dielectric properties of epoxy resin and epoxy micro-composites and nano-composites filled with silica has been studied. Nanocomposites were found to absorb significantly more water than unfilled epoxy. However, the microcomposite absorbed less water than unfilled epoxy: corresponding to reduced proportion of the epoxy in this composite. The glass transition temperatures of all the samples were measured by both differential scanning calorimetry and dielectric spectroscopy. The Tg decreased as the water absorption increased and, in all cases, corresponded to a drop of approximately 20K as the humidity was increased from 0% to 100%. This implied that for all the samples, the amount of water in the resin component of the composites was almost identical. It was concluded that the extra water found in the nanocomposites was located around the surface of the nanoparticles. This was confirmed by measuring the water uptake, and the swelling and density change, as a function of humidity as water was absorbed. The water shell model, originally proposed by Lewis and developed by Tanaka, has been further developed to explain low frequency dielectric spectroscopy results in which percolation of charge carriers through overlapping water shells was shown to occur. This has been discussed in terms of a percolation model. At 100% relative humidity, water is believed to surround the nanoparticles to a depth of approximately 5 monolayers. A second layer of water is proposed that is dispersed by sufficiently concentrated to be conductive; this may extend for approximately 25 nm. If all the water had existed in a single layer surrounding a nanoparticle, this layer would have been approximately 3 to 4 nm thick at 100%. This "characteristic thickness" of water surrounding a given size of nanoparticle appeared to be independent of the concentration of nanoparticles but approximately proportional to water uptake. Filler particles that have surfaces that are functionalized to be hydrophobic considerably reduce the amount of water absorbed in nanocomposites under the same conditions of humidity. Comments are made on the possible effect on electrical aging

Prediction of unsteady aerodynamic loadings caused by leading edge and trailing edge control surface motions in subsonic compressible flow: Computer program description

A digital computer program has been developed to calculate unsteady loadings caused by motions of lifting surfaces with leading edge or trailing edge controls based on the subsonic kernel function approach. The pressure singularities at hinge line and side edges have been extracted analytically as a preliminary step to solving the integral equation by collocation. The program calculates generalized aerodynamic forces for user supplied deflection modes. Optional intermediate output includes pressure at an array of points, and sectional generalized forces. From one to six controls on the half span can be accommodated