Session S10 - Poster Session (During Extended Coffee Breaks Throughout Conference).
POSTER session, Friday afternoon, October 24
Cochise, Memorial Union

[S10.001] Genome template model of evolutionary dynamics

We present a model of evolutionary dynamics which combines typical population-level processes, such as competitive reproduction and mortality, with longer time-scale population genetics. We connect genotype to phenotype using ``genome templates.'' Preliminary results for the evolution of fitness in a single population of asexually reproducing organisms will be discussed.

[S10.002] Multiscale modeling of chemotaxis

This poster will summarize our recent work on bridging stochastic and deterministic models of chemotaxis. In particular, we will present a Langevin model of cell movement and show its mean field connection to the Keller-Segel equations (which are the classic deterministic equations governing chemotaxis). We also present a novel numerical scheme for integrating the Keller-Segel equations. This scheme allows unprecedented accuracy and speed of computation in two and three dimensional systems, and provides new insights into the microscopic mechanisms underpinning deterministic advection-diffusion models.

[S10.003] Progress in NMR Studies of Liquid Ceramic Materials

The availability of molten, levitated samples of Al-containing ceramics at temperatures of 2,000^oC and higher permits a broad range of important materials to be investigated by the powerful techniques of NMR.\footnote Coutures, J-P., Massiot, D., Bessada, C., Echegut, P., Rifflet, J-C. amp; Taulelle F., Etude par RMN 27Al daluminates liquides dans le domaine 1600-2100 ^oC. C.R. Acad. Sci. Paris, 1990, 310, 1041. Standard measurements of chemical shift as a function of composition yield information concerning the bonding of Al and the structure of liquid phases, for both novel and well-studied refractory materials. Studies of incoherent motions in a sample, such as Al diffusion or time-dependent convective currents, may also be performed when magnetic field gradients are incorporated into the experimental NMR probe. Recent advances are reviewed, in several research areas.

[S10.004] Development of a Gallium Atomic Beam Source for Laser Manipulation

We are developing a gallium atomic beam source, for the purpose of using laser standing wave to directly focus the atoms during deposition onto a substrate. The atomic beam is mechanically collimated by slits to 0.4 mrad. This is comparable to the collimation that can be achieved by using laser cooling techniques. Optical pumping results of the atomic beam will be presented.

[S10.005] Electronic properties of UCoAl0.75Sn0.25 single crystal

The UCoAl0.75Sn0.25 crystallizes in the hexagonal ZrNiAl-type structure, like the parent compounds UCoAl (paramagnetic ground state, field-induced ferromagnetism at low temperatures) and UCoSn (ferromagnet, TC = 83 K). Studies of UCoAl1-xSnx polycrystals [1] revealed a minimum of Curie temperature (TC) and spontaneous magnetization for x = 0.25. We will report on the magnetic, electrical resistivity and specific heat behavior of UCoAl0.75Sn0.25 studied on a single crystal. The huge uniaxial magnetic anisotropy typical for UCoAl and UCoSn is preserved in the solid solution. The Arrott plot analysis of magnetization isotherms indicates ferromagnetism below 5.5 K. The resistivity and specific-heat anomalies around TC are attributed to the magnetic ordering transition. The anomalies are removed by magnetic fields above 1 T (B // c-axis) yielding large negative magnetoresistance effects in a wide interval around TC and reduction of the g-value extrapolated from paramagnetic regime, which is ascribed to suppression of spin fluctuations. A scenario will be presented considering the role of the 5f-ligand hybridization in the formation of the 5f magnetic moment and related phenomena.

[S10.006] Evolutionary dynamics of diploid populations

There has been much recent interest in constructing computer models of evolutionary dynamics. Typically these models focus on asexual population dynamics, which are appropriate for haploid organsims such as bacteria. Using a recently developed ``genome template'' model, we extend the algorithm to a sexual population of diploid organisms. We will present some early results showing the temporal evolution of mean fitness and genetic variation, and compare this to typical results from haploid populations.

[S10.007] Extinction times for birth-death processes through the adjoint approach

We consider the statistics of extinction times for two ecologically relevant models; namely, the stochastic logistic process (SLP) and a model of "neutral ecological drift." Using the adjoint approach popularized by van Kampen we are able to obtain exact expressions for the mean and variance of the extinction times. For the SLP, we find that the fluctuations in the extinction time become very large in precisely that region of parameter space for which the population is of moderate size.

[S10.008] Doping of CdSe Nanocrystals

What happens to a nanocrystal when it is doped with electrons? We doped CdSe nanocrystals with potassium metal and sodium biphenyl, potassium and sodium acting as the charge carriers. In order to monitor the properties of the doped nanocrystals we used Electron Spin Resonance and luminescence techniques. In this poster we present findings and problems encountered in doping CdSe nanocrystals.

[S10.009] Collisional Effects in Spherically Symmetric Low Temperature Plasma Oscillations

The present work has modeled the plasmas created at ultracold temperatures, excluding the effects of recombination. Using experimental conditions, numerical simulations have been used to follow the evolution of the plasma to steady state. A code based on a fluid model has been developed to find eigenmode frequencies for low order modes of the plasma. For moderately damped modes, the square of the plasma frequency goes linearly with temperature. Damping is found to be strong when the Debye length exceeds about one third of the plasma width.

[S10.010] High efficiency luminescent gallium nitride powders by direct synthesis from gallium metal and ammonia.

High quality as-synthesized gallium nitride (GaN) powders have been obtained by a complete reaction between high purity gallium metal and ultra high purity ammonia in a horizontal quartz tube reactor at 1100 ºC. Elemental analysis showed that the powders obtained by this method have a stoichiometric nitrogen concentration (16.73 weight hexagonal crystalline structure of the GaN synthesized. Electron microscopy showed that the powders are formed by at least two kinds of particles, small size platelets and large size needles. The GaN powders obtained by this method are light gray and produce high ultra-violet luminescence around 370 nm (3.35 eV, near band-edge emission) when they are excited by accelerated electrons (cathodoluminescence) or by high energy photons (photoluminescence) at room temperature.

[S10.011] Characterization of AlGaN epitaxial layer

Accurate aluminum compositions have been determined for AlxGa1-xN alloys whose rough compositions vary between 0

[S10.012] Anomalous random walks in a discrete model of chemotaxis

Chemotaxis is a fundamental process by which cells communicate and coordinate their movement. We present a discrete computer model of a small number of cells attempting to aggregate via chemical signaling and subsequent chemotactic response. We find a given cell can be severely hampered by responding to its local chemical environment, since this contains much information about the cell's own (mainly irrelevant) past movement. Emerging dynamics from this model can be characterized by anomalous random walk behavior, for which the wandering exponent strongly depends on model parameters. This indicates that low density chemotactic movement may be non-universal.

[S10.013] Selective Green or Red Emission From a New Polycrystalline Oxide Phosphor

Polycrystalline oxides of aluminum (Al) and europium (Eu) were obtained through combustion synthesis and annealing. XRD and TEM analysis show that the resulting powders present several crystalline phases including the recently discovered europium aluminate and Eu doped \alpha -Al _2 O_3 (sapphire). Photoluminescence (PL) yields a green emission from Eu^2+, while cathodoluminescence (CL) is red from the Eu^3+. This means that the Eu^2+ and Eu^3+ coexist within the polycrystals and there is an energy transfer mechanism that allows the selective excitation of each of them under different conditions. The spectrum of the Eu^3+ belongs to Eu substituting for Al in \alpha -Al _2 O_3, but in a distorted site. The emission of Eu^2+ corresponds to europium aluminate. These results are of interest because there is increasing attention on long-UV excited phosphors for white emitting devices and new, more efficient, CL phosphors for displays. Also, being able to select the emission (green or red) opens possibilities for more applications.

[S10.014] V802 Aql, a W Ursae Majoris Eclipsing Binary

New photometric observations were taken for V802 Aql, a W Ursae Majoris eclipsing binary system, between the nights of July 22, 2000 and August 31, 2003. V802 Aql was originally classified as a High Amplitude Delta Scuti (Bakos, 1950) and more recently as a W Ursae Majoris (Van Cauteren et. al., 2001, Hintz, 2000). Light curves generated from new data show it is a W Ursae Majoris type, and a more accurate period has been determined. New times of primary and secondary minima are included, and can be used in future research for changes in the star’s period. In addition to the period of the star, several other parameters for the system have been estimated by fitting our data to a curve using Nightfall software. These other parameters, including mass, are useful in the understanding the evolutionary path of stars in general.

[S10.015] A stochastic model of enzyme kinetics

Enzyme kinetics is generally modeled by deterministic rate equations, and in the simplest case leads to the well-known Michaelis-Menten equation. It is plausible that stochastic effects will play an important role at low enzyme concentrations. We have addressed this by constructing a simple stochastic model which can be exactly solved in the steady-state. Throughout a wide range of parameter values Michaelis-Menten dynamics is replaced by a new and simple theoretical result.

[S10.016] A Consideration of Torsion and Coriolis Effects in Einstein’s Field Equations

Recent observation of distant acceleration of observed supernovae and other cosmological objects lead to deviation from the usual Hubble’s constant, and resulted in the reintroduction of a nonzero cosmological constant in order to not only explain cosmological acceleration but also to formulate a model of galactic, stellar and other cosmological rotational structures. We introduce a variable form of \Lambda (M_4) where M_4 is the four dimensional Minkowski space. We also introduce additional terms in the stress energy tensor which accommodates torsion and the coriolis forces [1,2]reconciling the new terms with the properties of the inhomogeneous Lorentz transformations which are made so as to preserve the affine connections. Discussions are made about the implications of galactic, supernovae, etc. structures; also proper frame of reference is considered in detail.

(1) R. Hammond, Gen. Rel. And Grav. 26, 247 (1994), (2) J.P. Vigier, lett. Nuovo Cimento 24, 258 (1979).

[S10.017] Elevated Temperature Scanning Tunneling Microscopy of Ge on Si(100)

The Ge/Si(100) system has been studied intensely in the past due to the fact that is a great model for observing the mechanisms involved in the Stranaski-Krastanov growth mode, described as layer-by-layer growth followed by the formation of islands, or dots. These mechanisms, driven by a 4.2lattice mismatch, are still not fully understood. Elevated temperature scanning tunneling microscopy (ET-STM) can assist us in better understanding these mechanisms by observing the kinetics of Ge on the surface of Si(100) at the atomic level. Currently, we have an ultra high vacuum ET-STM capable of depositing Ge via digermane on Si(100) substrates held at temperatures between 350 to 650 degrees Celsius. Preliminary results have resulted in 'movies' showing the growth of the wetting layers which then lead to the formation of Ge quantum dots. From these movies we are able to monitor aspects of Ge growth such as quantum dot volume over time, revealing critical radii as a function of growth temperature.

[S10.018] Astronomical Image processing in IDL

This Abstract, 5008, is Not Available.

[S10.019] The Lorentz Aether Theory

A careful look at the Lorentz Ether Theory (LET) and the Theory of Special Relativity (SR) tells us how they are the same and how they are different. They have the identical math. Thus, they produce the identical results. They are thus one and the same theory! If any fact is found to support one, it must also support the other. If one fails, so will the other, based upon the same facts. SR is based only upon math: a math constant, c, and a restriction upon the form of the equations. LET has a physical base, and from what physical things do, the math is derived. For this reason, SR cannot give us physical explanations for why c is constant, or why the equations are limited in form. SR has no physical interpretation. LET, being a physically based theory, can provide physical explanations as to what occurs. It must be concluded: SR is the correct math for our reality, but LET is the correct physics that goes with the correct math. Therefore, they support each other. We need both theories. They make each other a stronger theory. We can no longer ignore these facts.

[S10.020] About the calculation of the photon power

Owing to the pioneer works of Einstein and Planck at the beginning of the 20 century, we are able to calculate the energy of one photon today. With rapid growing meaning of the nanotechnologies and the development of the processes, which are based on the laser and solar power, the factor power will play a larger role in the future, however. The performance analysis and the determination of the efficiency makes a competent and safe control as well as the more economical use of complex plants and system processes possible. Usually the value of efficiency, which is important for technical and economic optimization is defined by the relationship between the supplied power and the won work. On which factors the power of the photon is dependent and how it changes quantitatively, is not clearly. From thermodynamics we know that the power can be determined by the temporal change of the energy. Hereby the following equation can be considered: P = \left| \fracdEdt \right| According to the world-famous formula of Planck and to the model of the photon, which was suggested in the applications [1, 2], the formula for the practical determination of the power of the light particle can be deduced. With the differentiation of the formula of Planck E = h \cdot f in the form \fracdEdt = h \cdot \fracdfdt as well as the use of the impulse equation [2, 3] with consideration of the rotation of the photon, the equation for the calculation of the power was derived. It resulted that the power can be represented in the following form: P = const \cdot f^2 The derivativing of this formula under appropriate boundary conditions will be entered more in detail during the meeting.

References 1. About the dualism of the light. S. Reissig, The 12th General Conference of the European Physical Society "Trends in Physics”, 2002 2. "About the nature of the photon. S. Reissig, www.efbr.de/de/publikationen/EFBR3. Bewegungsgleichung der Photonen. S. Reissig. www.efbr.de/de/publikationen/EFBR

[S10.021] Possible origin of inertial mass.

A quantity we call “rest mass” naturally originates in the system of standing relativistic waves (i.e., waves moving with the same speed in any reference frame) as a mathematical by-product of Lorents transformations. Another by-product of these transformations (in such system) is de Broigle wave. These derivations make also interesting suggestion for the origin of least action principle.

[S10.022] On the relationship between Hamiltonian chaos and classical gravity

It is known that Hamiltonian equations of motion for low-dimensional chaotic systems are typically formulated using fractional derivatives. The evolution of such systems is governed by the fractional diffusion equation. We confirm, in this context, that the dynamics of a Brownian particle driven by path-dependent random fluctuations evolves towards Hamiltonian chaos and fractional diffusion. The corresponding motion of the particle has a time-dependent and nowhere vanishing acceleration. Invoking the equivalence principle of General Relativity leads to the conclusion that fractional diffusion is locally equivalent to a transient gravitational field. It is shown that gravity becomes renormalizable as Newton's constant acquires a positive mass dimension.

Part S of program listing