Degradation mechanism, hydrocarbon polymers Final technical report

Degradation of hydrocarbon polymers by exposure to 275 F for 400 hours in presence and in absence of ammonium perchlorat

Quality assurance procedures for V378A matrix resin

A characterization methodology has been developed on which to base quality assurance procedures for U.S. Polymeric V378A bismaleimide matrix resin. Chemical composition is established by partition reverse phase and size exclusion liquid chromatography. Cure rheology behavior is quantitatively characterized by dynamic viscoelastic analysis using the parallel plate technique. The overall cure process is characterized by differential scanning calorimetry. The sensitivity of the procedures is evaluated by studying the effects of ambient out time on the chemical end behaviorial properties of the resin

Topological Constraints on the Charge Distributions for the Thomson Problem

The method of Morse theory is used to analyze the distributions of unit charges interacting through a repulsive force and constrained to move on the surface of a sphere -- the Thomson problem. We find that, due to topological reasons, the system may organize itself in the form of pentagonal structures. This gives a qualitative account for the interesting ``pentagonal buttons'' discovered in recent numerical work.Comment: 10 pages; dedicated to Rafael Sorkin on his 60th birthda

Symmetric coupling of four spin-1/2 systems

We address the non-binary coupling of identical angular momenta based upon the representation theory for the symmetric group. A correspondence is pointed out between the complete set of commuting operators and the reference-frame-free subsystems. We provide a detailed analysis of the coupling of three and four spin-1/2 systems and discuss a symmetric coupling of four spin-1/2 systems.Comment: 20 pages, no figure

Sex Differences in the Perceived Dominance and Prestige of Women With and Without Cosmetics

Human social status has long been of interest to evolutionary and social psychologists. The question of who gets to control resources and be a leader has garnered a lot of attention from these and other fields, and this thesis examines evidence for there being two different mechanisms of achieving high status, and their correlates. The mechanisms are 1) Dominance: being aggressive, manipulative and forcing others to follow you, and 2) Prestige: possessing qualities which make others freely follow you. Chapter 1 is an introductory chapter in which I explain selection pressures, group formation, and the need for social hierarchies; I then describe the two proposed methods of attaining social status and how facial characteristics can give clues as to an individual’s social status. In Chapter 2, my first experimental chapter, I examined how faces created to appear either high in dominance or high in prestige were judged with respect to those traits as well as personality characteristics. Taking this further, in Chapter 3, I looked at how natural variation in real faces would reflect differences in other- and self-perceived ratings of dominance and prestige. Chapter 4 served to examine whether, given a set of words related to social status, I would find differences in what words were placed into dominant or prestige categories. Findings within these chapters are consistent with dominance and prestige being separable methods of attaining high status, from differences in facial appearance (Chapter 2 and 3), to personality characteristics (Chapter 2), to word usage (Chapter 4). Once I had established that these were two distinct routes to achieving high status, I chose to focus on dominance in Chapter 5 and explored the conceptual relationships between dominance and facial expressions. I found that manipulating perceptions of dominance affected how intense expressions of anger, sadness, and fear were perceived (Chapter 5). As there has been a paucity of research in the area of women’s social status, in Chapter 6, I went on to explore what effects cosmetics use in women would have on their perceived social status. I found differences in how men and women perceived women wearing cosmetics, which again points to a distinction between dominance and prestige. My thesis then presents a broad view of the two different mechanisms for attaining high status. Using new methods not otherwise used in exploring dominance and prestige I was able to explore correlates and indicators, as well as perceptions of both strategies. These findings will allow us to determine who might be capable of attaining social status, which of the two methods they might use, as well as what implicit associations we hold about each. They will also open doors for future research into the two strategies, and even help interpret previous research, as many previous studies simply relate to high status and do not distinguish between dominance and prestige

Insulating charge density wave for a half-filled SU(N) Hubbard model with an attractive on-site interaction in one dimension

We study a one-dimensional SU(N) Hubbard model with an attractive on-site interaction and $N>2$ at half-filling on the bipartite lattice using density-matrix renormalization-group method and a perturbation theory. We find that the ground state of the SU(N) Hubbard model is a charge density wave state with two-fold degeneracy. All the excitations are found to be gapful, resulting in an insulating ground state, on contrary to that in the SU(2) case. Moreover, the charge gap is equal to the Cooperon gap, which behaves as $-2Nt^2/(N-1)U$ in the strong coupling regime. However, the spin gap $\Delta_{s}$ and the quasiparticle gap $\Delta_{1}$ as well open exponentially in the weak coupling region, while in the strong coupling region, they linearly depend on $U$ such that $\Delta_{s}\sim -U(N-1)$ and $\Delta_{1}\sim -U(N-1)/2$.Comment: 7 pages, 7 figure

Multiparticle SUSY quantum mechanics and the representations of permutation group

The method of multidimensional SUSY Quantum Mechanics is applied to the investigation of supersymmetrical N-particle systems on a line for the case of separable center-of-mass motion. New decompositions of the superhamiltonian into block-diagonal form with elementary matrix components are constructed. Matrices of coefficients of these minimal blocks are shown to coincide with matrices of irreducible representations of permutations group S_N, which correspond to the Young tableaux (N-M,1^M). The connections with known generalizations of N-particle Calogero and Sutherland models are established.Comment: 20 pages, Latex,no figure