Programs & Awards  
Follow SPS on: Twitter Facebook YouTube Photobucket The Nucleus Email and Share
2005 SPS Outstanding Student Awards for Undergraduate Research
Recipients: 2013 | 2012 | 2011 | 2010 | 2009 | 2008 | 2007 | 2006 | 2005 | 2004 | 2003 | About the Award

Note: The awardees represented SPS and presented their research at the 2005 International Conference of Physics Students in Coimbra, Portugal.


Brook Chuzles, University of Wisconsin-La Crosse

Brook Chuzles"The Discovery and Measurement of Optically Pumped Molecular Laser Emissions and Their Use in the Investigation of Unstable Molecular Species"
Meeting Report & Photos

Faculty Mentor: Dr. Michael Jackson

Research Abstract
For the past several years, a variety of stable and unstable molecular species have been investigated in the infrared and far-infrared regions using several spectroscopic systems. The initial research performed at the University of Wisconsin-La Crosse (UWL) involved the discovery of new optically pumped laser emissions from a variety of stable molecular species, including hydrazine and partially deuterated methanol isotopes. New laser emissions were discovered in the short-wavelength portion of the far-infrared region, typically defined as wavelengths below 150 micron. Once detected, the operating characteristics of these laser emissions (including their wavelength, operating pressure, power and polarization relative to the carbon dioxide pump laser) were measured. A three-laser heterodyne system was then assembled to measure the frequencies of these laser emissions to fractional uncertainties of a few parts in ten million. This work includes the first measurement ever performed on an FIR laser emission generated by the fully deuterated isotope of hydrazine. Once measured, these laser lines can be used as strong, coherent sources of far-infrared radiation for the investigation of unstable molecular species with the laser magnetic resonance (LMR) spectroscopic technique. Along with the far-infrared LMR spectrometer system recently constructed at UW-L, the infrared LMR spectrometer system at the University of Oxford, England has been used to re-investigate the NCN radical, resulting in the assignment of numerous absorption signals in two vibrational bands. In this presentation, I will provide an overview of the research performed during the past three years along with the experimental systems used in this work, including the optically pumped molecular laser, three-laser heterodyne and laser magnetic resonance spectrometer systems.

 
Sohang Gandhi, The University of Central Florida

"Inversions of Gamow's Formula and Inverse Scattering"
Meeting Report & Photos

Faculty Mentor: Costas J. Efthimiou

Research Abstract
Eugen Merzbacher has commented that [1] "among all the successes of quantum mechanics as it evolved in the third decade of the 20th century, none was more impressive than the understanding of the tunnel effect-the penetration of matter waves and the transmission of particles through a high potential barrier." The tunnel effect provided a straightforward and remarkable explanation of the radioactive a-decay of nuclei. George Gamow was one of thealthough not the sole- protagonists in the discovery of the theory of a-decay [1,2] and the basic formula, equation (1), that underlies tunneling through a potential barrier is often referred to as-perhaps unjustly-Gamow's penetrability factor (see, for example, p. 62 of [2]).

(1)

In the above, T(E) is the transmission coefficient giving the probability for the particle to surpass the barrier, U(X) is the potential, E is the energy, and Xl (E) and x2(E) are the classical turning points.

Leaving aside Gamow's mischievous account of history, we shall discuss how knowledge of the tunneling behavior of a potential can be used to determine the potential itself. We shall in the process invert equation (1) and thus find a solution to a general integral equation of a form similar to Abel's equation. We shall also apply our solution to an example taken from the cold emission effect.

Our treatment, making use of Gamow's formula, provides avenue for treating the quantum mechanical problem of inverse scattering in a way which is analogous to the classical problem. The classical problem shall be reviewed and compared to the present results with a focus on the issue of uniqueness.

Lazenby and Griffiths [4] have remarked that it is curious that the solutions to the classical problem are not determined uniquely whereas in the quantum mechanical analogue the solution is unique. It is further remarked that "given the transmission coefficient T (the probability that the particle will surpass the barrier) as a function of energy E, (the potential) may be recovered by the method of Gel'fand and Levitan." As will be discussed, this statement is not accurate as it stands. We shall show that the quantum mechanical transmission coefficient, T(E), the analog of the classical scattering data, is only sufficient to determine the potential to within a solution family, just as is the case in classical mechanics. We shall then develop insight into how it is that the method of Gel'fand and Levitan [5] comes to yield a unique solution.

References:

  1. E. Merzbacher, Phys. Today 55(8) (2002) 44.
  2. RH. Stuewer, in The kaleidoscope of Science, vol 1, E. Ullmann-Margalit, ed., D. Reidel, Hingham, 1986; J. Mehra, H. Rechenberg, The Historical Development of Quantum Theory, vol 6, part 1, Springer-Verlag 2000.
  3. F. Constantinescu, E. Magyari, Problems in Quantum Mechanics, Pergamon 1982.
 
Scooter Johnson, Lewis & Clark College

Scooter Johnson"Mechanisms of Transport and Release of Dense-Core Granules Containing Tissue Plasminogen Activator in Developing Hippocampal Neurons"
Meeting Report & Photos

Faculty Mentor: Dr. Bethe A. Scalettar

Research Abstract
Dense-core granules (DCGs) are organelles found in specialized secretory cells, including neuroendocrine cells and neurons. Neuronal DCGs facilitate many critical processes, including the transport and secretion of proteins involved in learning, and yet their transport and release are poorly understood. We have used wide-field and total internal reflection fluorescence microscopy, in conjunction with transport theory, to visualize the transport and release ofDCGs containing a tissue plasminogen activatorgreen fluorescent protein hybrid in cell bodies, neurites, and growth cones of developing hippocampal neurons and to quantify the roles that diffusion, directed motion, and immobility play in these processes. Our results demonstrate that shorter-ranged transport ofDCGs near sites of release in hippocampal neurons and neuroendocrine cells differs markedly. Specifically, the immobile action ofDCGs within growth cones and near the plasma membrane of hippocampal neurons is small and relatively unaltered by actin disruption, unlike in neuroendocrine cells. Moreover, transport ofDCGs in these domains of hippocampal neurons is varied, being significantly rapid and directed as well as slow and diffusive. Our results also demonstrate that granule release is preceded by substantial movement and varied transport; this movement may facilitate delivery of DCG cargo in hippocampal neurons, given the relatively low abundance of neuronal DCGs. In addition, the extensive mobility ofDCGs in hippocampal neurons argues strongly against the hypothesis that cortical actin is a major barrier to membrane proximal DCGs in these cells. Instead, our results suggest that extended release of DCG cargo from hippocampal neurons arises from diversity in DCG mobility.

   Home  |  Search   |   Site Map  |   Privacy   |   Contact SPS