Isolation & Characterization of Bacteria in the Built Environment: Measuring The Effect of Pharmaceuticals on Growth

This work reports the isolation and characterization of bacteria from the built environment at Gettysburg College in Gettysburg, PA. Surfaces of a water fountain on campus were swabbed and serially streaked to isolate multiple bacteria on R2A agar. Following multiple rounds of growth, the unknown microbial candidates were narrowed to two visibly­distinct organisms. Morphological characterization and phylogenetic identification based on 16S rDNA sequencing revealed that the isolates were Chryseobactierum hispalense and Microbacterium maritypicum. We report synergistic biofilm formation between Chryseobactierum hispalense and Microbacterium maritypicum. The contamination of drinking water with varying levels of personal care products and pharmaceuticals (PCPPs) is well documented. Additionally, these environmental pollutants and their derivatives affect aquatic life, as illustrated with effect of the antidepressant fluoxetine on mudsnails. To determine if previously reported contaminants affect freshwater bacteria, we assessed both planktonic growth and biofilm formation following exposure to nalidixic acid (non­fluorinated quinolone antibiotic), diphenhydramine (over­the­counter drug Benadryl), and fluoxetine (Prozac)

Quantum Hall Exciton Condensation at Full Spin Polarization

Using Coulomb drag as a probe, we explore the excitonic phase transition in quantum Hall bilayers at nu=1 as a function of Zeeman energy, E_Z. The critical layer separation d/l for exciton condensation initially increases rapidly with E_Z, but then reaches a maximum and begins a gentle decline. At high E_Z, where both the excitonic phase at small d/l and the compressible phase at large d/l are fully spin polarized, we find that the width of the transition, as a function of d/l, is much larger than at small E_Z and persists in the limit of zero temperature. We discuss these results in the context of two models in which the system contains a mixture of the two fluids.Comment: 4 pages, 3 eps figure

Quantum Hall Exciton Condensation at Full Spin Polarization

Using Coulomb drag as a probe, we explore the excitonic phase transition in quantum Hall bilayers at ν_T = 1 as a function of Zeeman energy E_Z. The critical layer separation (d/ℓ)_c for exciton condensation initially increases rapidly with E_Z, but then reaches a maximum and begins a gentle decline. At high E_Z, where both the excitonic phase at small d/ℓ and the compressible phase at large d/ℓ are fully spin polarized, we find that the width of the transition, as a function of d/ℓ, is much larger than at small E_Z and persists in the limit of zero temperature. We discuss these results in the context of two models in which the system contains a mixture of the two fluids

Exciton Transport and Andreev Reflection in a Bilayer Quantum Hall System

We demonstrate that counterflowing electrical currents can move through the bulk of the excitonic quantized Hall phase found in bilayer two-dimensional electron systems (2DES) even as charged excitations cannot. These counterflowing currents are transported by neutral excitons which are emitted and absorbed at the inner and outer boundaries of an annular 2DES via Andreev reflection

Evidence for an anomalous current phase relation in topological insulator Josephson junctions

Josephson junctions with topological insulator weak links can host low energy Andreev bound states giving rise to a current phase relation that deviates from sinusoidal behaviour. Of particular interest are zero energy Majorana bound states that form at a phase difference of $\pi$. Here we report on interferometry studies of Josephson junctions and superconducting quantum interference devices (SQUIDs) incorporating topological insulator weak links. We find that the nodes in single junction diffraction patterns and SQUID oscillations are lifted and independent of chemical potential. At high temperatures, the SQUID oscillations revert to conventional behaviour, ruling out asymmetry. The node lifting of the SQUID oscillations is consistent with low energy Andreev bound states exhibiting a nonsinusoidal current phase relation, coexisting with states possessing a conventional sinusoidal current phase relation. However, the finite nodal currents in the single junction diffraction pattern suggest an anomalous contribution to the supercurrent possibly carried by Majorana bound states, although we also consider the possibility of inhomogeneity.Comment: 6 pages, 4 figure

Phase Coherence and Andreev Reflection in Topological Insulator Devices

Topological insulators (TIs) have attracted immense interest because they host helical surface states. Protected by time-reversal symmetry, they are robust to non-magnetic disorder. When superconductivity is induced in these helical states, they are predicted to emulate p-wave pairing symmetry, with Majorana states bound to vortices. Majorana bound states possess non-Abelian exchange statistics which can be probed through interferometry. Here, we take a significant step towards Majorana interferometry by observing pronounced Fabry-Perot oscillations in a TI sandwiched between a superconducting and normal lead. For energies below the superconducting gap, we observe a doubling in the frequency of the oscillations, arising from the additional phase accumulated from Andreev reflection. When a magnetic field is applied perpendicular to the TI surface, a number of very sharp and gate-tunable conductance peaks appear at or near zero energy, which has consequences for interpreting spectroscopic probes of Majorana fermions. Our results demonstrate that TIs are a promising platform for exploring phase-coherent transport in a solid-state system.Comment: 9 pages, 7 figure

The Prairie Naturalist, Volume 38, Number 2, June 2006

The Prairie Naturalist (June 2006) Volume 38, Issue 2, full issue. Feeding Habitats of Spring-Migrating Blackbirds in East-central South Dakota, by Richard S. Sawin, George M. Linz, William J. Bleier, and H. Jeffrey Homan, pages 73-84. Brood Break-up and Juvenile Dispersal of Lesser Prairie-chicken in Kansas, by James C. Pitman , Brent E. Jamison, Christian A. Hagen, Robert J. Robel, and Roger D. Applegate, pages 74-99. Population Biology of Pumpkinseed in Enemy Swim Lake, South Dakota, by Eric J. Weimer and Michael L. Brown, pages 101-111. Reproductive Development in the Sicklefin Chub in the Missouri and Lower Yellowstone Rivers, by Douglas J. Dieterman , Eric Roberts, Patrick J. Braaten, and David L. Galat, pages 113-130. Christmas Bird Counts for North Dakota 2005, by Robert N. Randall, pages 131-136. First Record of Hairy Woodruch from South Dakota [Notes], by Katherine A. Zacharkevics, pages 137-138 Raptors in Your Pocket: A Guide to Great Plains Birds of Prey. Dana Gardner, 2006, University of Iowa Press, 16 pages (laminated), book review by Paul M. Konrad, pages 139-140. Dakota Flora: A Seasonal Sampler, David J. Ode, 2006, South Dakota State Historical Society Press, Pierre, South Dakota, 260 pages, book review by Bonnie Heidel, pages 141-142. The National Grasslands, Francis Moul, 2006, University of Nebraska Press, Lincoln, Nebraska, 153 pages, book review by F. L. Knopf, pages 143-144. The cover and its artist, inside back cover. Table of contents, back cover

The Prairie Naturalist, Volume 38, Number 4, December 2006

Full issue of The Prairie Naturalist (December 2006), volume 38, number 4. Amphibians and Reptiles in a MixedGrass Prairie in Northwestern North Dakota by Robert K. Murphy, Robert F. Danley, and Patricia K. Moore, pages 207-212 Morphometrics of Six Turtle Species from South Dakota by Sarah J. Bandas and Kenneth F. Higgins, pages 213-222 Evaluation of Habitat Enhancement Structure Use by Spotted Bass by Stanley L. Proboszcz and Christopher S. Guy, pages 223-238 Evaluating Diet Composition of Pronghorn in Wind Cave National Park, South Dakota by Christopher N. Jacques , Jaret D. Sievers, Jonathan A. Jenks, Chad L. Sexton, and Daniel E. Roddy, pages 239-250 Spatial and Seasonal Variation in Wildlife-Vehicle Collisions by Jonathan M. Conard and Philip S. Gipson, pages 251-260 Volume 38 reviewers, page 261 Volume 38 author index, pages 262-267 Volume 38 subject index, pages 268-270 The cover and its artist, inside back cover Table of contents, back cove