A dust scattering model of M82

This thesis contains an investigation into polarisation produced by light scattered within nebulae and galaxies. In the first chapter a general outline of mechanisms, producing polarisation is given. This is followed in chapter two by a detailed analysis of the theory of scattering. Here we show the formulation of the theory for scattering from small particles (Raylei^ scattering) and scattering from larger particles, (Mie theory). Chapter three gives an overview of interstellar grains, their composition, growth, destruction, size distributions and the possible sources of their origins. This is followed in the next chapter by a study of the galaxy m82. Here is given the scientific development of the galaxy showing previous models developed and the controversy which has built up over the years on whether the galaxy actually exploded or not. Chapter five contains a dust scattering model of the galaxy. This is based upon the hypothesis that the galaxy has drifted into an enormous intergalactic dust cloud. The results and consequences of the model are presented in chapter six. The dust scattering model used for M82 assumed Rayleigh scatterers. Chapter seven shows the results from model nebulae consisting of Mie particles. Here discussion is given to the effect on the predicted results when varying the properties of the grains. We also mention the potentials of other forms of polarisation techniques

Coral Reef Formation

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Particle phenomenology on noncommutative spacetime

We introduce particle phenomenology on the noncommutative spacetime called the Groenewold-Moyal plane. The length scale of spcetime noncommutativity is constrained from the CPT violation measurements in $K^{0}-\bar{K}^{0}$ system and $g-2$ difference of $\mu^+ - \mu^-$. The $K^{0}-\bar{K}^{0}$ system provides an upper bound on the length scale of spacetime noncommutativity of the order of $10^{-32} \textrm{m}$, corresponding to a lower energy bound $E$ of the order of $E \gtrsim 10^{16}\textrm{GeV}$. The $g-2$ difference of $\mu^+ - \mu^-$ constrains the noncommutativity length scale to be of the order of $10^{-20} \textrm{m}$, corresponding to a lower energy bound $E$ of the order of $E \gtrsim 10^{3}\textrm{GeV}$. We also present the phenomenology of the electromagnetic interaction of electrons and nucleons at the tree level in the noncommutative spacetime. We show that the distributions of charge and magnetization of nucleons are affected by spacetime noncommutativity. The analytic properties of electromagnetic form factors are also changed and it may give rise to interesting experimental signals.Comment: 10 pages, 3 figures. Published versio

Effective Vortex Pinning in MgB2 thin films

We discuss pinning properties of MgB2 thin films grown by pulsed-laser deposition (PLD) and by electron-beam (EB) evaporation. Two mechanisms are identified that contribute most effectively to the pinning of vortices in randomly oriented films. The EB process produces low defected crystallites with small grain size providing enhanced pinning at grain boundaries without degradation of Tc. The PLD process produces films with structural disorder on a scale less that the coherence length that further improves pinning, but also depresses Tc

The Decay Lifetime of Polarized Fermions in Flight

Based on the parity violation in Standard model, we study the dependence of lifetime on the helicity of an initial-state fermion in weak interactions. It is pointed out that if the initial fermions in the decays are longitudinally polarized, then the decay lifetime of left-handed polarized fermions is different from that of right-handed polarized fermions in flight with a same velocity in a same inertial system.Comment: 7 pages, Late

Electrothermal fracturing of tensile specimens

Pulling device consisting of structural tube, connecting rod, spring-loaded nuts, loading rod, heating element, and three bulkheads fractures tensile specimens. Alternate heating and cooling increases tensile loading by increments until fracturing occurs. Load cell or strain gage, applied to pulling rod, determines forces applied

Pyrolysis-GC×GC-TOFMS to characterize carbonaceous chondrites

Using pyrolysis-GCxGC-TOFMS to analyze organic carbon in carbonaceous chondrites gives a massive increase in both sensitivity and structural information from samples when compared to traditional Py-GC-MS

Checklists of selected shallow-water marine invertebrates of Florida

The initial draft of this list was based, in part, on information in American Seashells, second edition (Abbott, 1974) and on lists of mollusks prepared by the Council of Systematic Malacologists and the American Malacological Union for the American Fisheries Society (Turgeon et al., 1988; Turgeon et al., 1998).The Florida list was created by selecting from those larger lists the estuarine and marine species known from eastern North America and then by reducing that set of names, first by deleting the names of species not known from Florida and then by deleting the names of several hundred species known only from intermediate and deepwater regions of the continental shelf off Florida

Vortices Clustering: The Origin of the Second Peak in the Magnetisation Loops of High Temperature Superconductors

We study vortex clustering in type II Superconductors. We demonstrate that the ``second peak'' observed in magnetisation loops may be a dynamical effect associated with a density driven instability of the vortex system. At the microscopic level the instability shows up as the clustering of individual vortices at (rare) preferential regions of the pinning potential. In the limit of quasi-static ramping the instability is related to a phase transition in the equilibrium vortex system.Comment: 11 pages + 3 figure