Studies on electrochemical formation and reduction of oxide films on noble and transition metals Interim report

Surface oxidation of Pt electrodes in pure solutions and resolution of various stages of oxygen uptake by Pt surface

The Interaction Between Perfectionism and Rumination Predicting State Self-compassion

Recent research has revealed self-compassion to be associated with many aspects of mental wellness. The present study investigates the relationship between perfectionism and rumination in predicting state self-compassion separately for both conscientious and self-evaluative forms of perfectionism. We hypothesized that perfectionism would interact with rumination in predicting state self-compassion such that there would be a negative association between occurrence of rumination and state-self compassion that would be more prominent in those with lower levels of perfectionism in regards to self-evaluative, but not conscientious perfectionism. To test these predictions, participants filled out a perfectionism inventory and completed a four minute ruminative (or non-ruminative) writing task before completing a sate self-compassion questionnaire. Although we found no significant interaction between self-evaluative perfectionism and rumination, our results reveal self-evaluative perfectionism to be inversely related to state self-compassion such that people with lower levels of self-evaluative perfectionism generally experienced greater momentary states of self-compassion

Applications of high thermal conductivity composites to electronics and spacecraft thermal design

Recently, high thermal conductivity continuous graphite fiber reinforced metal matrix composites (MMC's) have become available that can save much weight over present methods of heat conduction. These materials have two or three times higher thermal conductivity in the fiber direction than the pure metals when compared on a thermal conductivity to weight basis. Use of these materials for heat conduction purposes can result in weight savings of from 50 to 70 percent over structural aluminum. Another significant advantage is that these materials can be used without the plumbing and testing complexities that accompany the use of liquid heat pipes. A spinoff of this research was the development of other MMC's as electronic device heat sinks. These use particulates rather than fibers and are formulated to match the coefficient of thermal expansion of electronic substrates in order to alleviate thermally induced stresses. The development of both types of these materials as viable weight saving substitutes for traditional methods of thermal control for electronics packaging and also for spacecraft thermal control applications are the subject of this report

Virtual Pitch and Pitch Shifts in Church Bells

It is well established that musical sounds comprising multiple partials with frequencies approximately in the ratio of small integers give rise to a strong sensation of pitch even if the lowest or fundamental partial is missing—the so-called virtual pitch effect. Experiments on thirty test subjects demonstrate that this virtual pitch is shifted significantly by changes in the spacing of the constituent partials. The experiments measured pitch by comparison of sounds of similar timbre and were automated so that they could be performed remotely across the Internet. Analysis of the test sounds used shows that the pitch shifts are not predicted by Terhardt’s classic model of virtual pitch. The test sounds used were modelled on the sounds of church bells, but a further experiment on seventeen test subjects showed that changes in partial amplitude only had a minor effect on the pitch shifts observed, and that a pitch shift was still observed when two of the lowest frequency partials were removed, so that the effects reported are of general interest

Electron Microscope Studies of Heteroduplex DNA from a Deletion Mutant of Bacteriophage phi X-174

A population of double-stranded replicative form of DNA molecules from bacteriophage phi X-174 carrying a deletion of about 9% of the wild-type DNA has been discovered in a sample cultivated under conditions where the phage lysozyme gene is nonessential. The structures of deleted monomers, dimers, and trimers were studied by the electron microscope heteroduplex method. The dimers and trimers are head-to-tail repeats of the deleted monomers. Some interesting examples of the dynamical phenomenon of branch migration in vitro have been observed in heteroduplexes of deleted dimer and trimer strands with undeleted monomer viral strands from the wild-type phage

Development of a polysilicon process based on chemical vapor deposition, phase 1

The development of a dichlorosilane-based reductive chemical vapor deposition process for the production of polycrystalline silicon is discussed. Experimental data indicate that the ease of ignition and explosion severity of dichlorosilane (DCS)/air mixtures is substantially attenuated if the DCS is diluted with hydrogen. Redesign of the process development unit to accommodate safety related information is described. Several different sources of trichlorosilane were used to generate a mixture of redistributed chlorosilanes via Dowex ion exchange resin. The unseparated mixtures were then fed to an experimental reactor in which silicon was deposited and the deposited silicon analyzed for electrically active impurities. At least one trichlorosilane source provided material of requisite purity. Silicon grown in the experimental reactor was converted to single crystal material and solar cells fabricated and tested

Stakeholder identification in the requirements engineering process

Adequate, timely and effective consultation of relevant stakeholders is of paramount importance in the requirements engineering process. However, the thorny issue of making sure that all relevant stakeholders are consulted has received less attention than other areas which depend on it, such as scenario-based requirements, involving users in development, negotiating between different viewpoints and so on. The literature suggests examples of stakeholders, and categories of stakeholder, but does not provide help in identifying stakeholders for a specific system. In this paper, we discuss current work in stakeholder identification, propose an approach to identifying relevant stakeholders for a specific system, and propose future directions for the work

A new fabrication method for precision antenna reflectors for space flight and ground test

Communications satellites are using increasingly higher frequencies that require increasingly precise antenna reflectors for use in space. Traditional industry fabrication methods for space antenna reflectors employ successive modeling techniques using high- and low-temperature molds for reflector face sheets and then a final fit-up of the completed honeycomb sandwich panel antenna reflector to a master pattern. However, as new missions are planned at much higher frequencies, greater accuracies will be necessary than are achievable using these present methods. A new approach for the fabrication of ground-test solid-surface antenna reflectors is to build a rigid support structure with an easy-to-machine surface. This surface is subsequently machined to the desired reflector contour and coated with a radio-frequency-reflective surface. This method was used to fabricate a 2.7-m-diameter ground-test antenna reflector to an accuracy of better than 0.013 mm (0.0005 in.) rms. A similar reflector for use on spacecraft would be constructed in a similar manner but with space-qualified materials. The design, analysis, and fabrication of the 2.7-m-diameter precision antenna reflector for antenna ground tests and the extension of this technology to precision, space-based antenna reflectors are described