Circular Dichroism of RbHe and RbN2_2 Molecules

We present measurements of the circular dichroism of optically pumped Rb vapor near the D1 resonance line. Collisions with the buffer gases $^3$He and N$_2$ reduce the transparency of the vapor, even when fully polarized. We use two methods to measure this effect, show that the He results can be understood from RbHe potential curves, and show how this effect conspires with the spectral profile of the optical pumping light to increase the laser power demands for optical pumping of very optically thick samples

Free Flight Store Simulation Using Beggar

The complete numerical solution of the airflow around a store in extended free flight is of particular importance to the United States Air Force. Beggar is the primary Computational Fluid Dynamics (CFD) program used by the USAF to obtain solutions for store separations. However, Beggar\u27s ability to simulate a store in free flight is limited because the store must fall through a static background mesh, eventually reaching a point where the solution will fail. The length of any free flight simulation is consequently limited by the height of the background mesh. Code modifications are made to Beggar to remove this requirement by pinning the store in the background mesh at its center of gravity. Rotations are accomplished within the background mesh, but translations are reflected as changes in the grid speeds of the background mesh. This allows the numerical simulation to continue indefinitely. Beggar\u27s ability to model moving components (e.g. control surfaces) in multi-body problems is fully preserved. The modified code is applied to the MK-84 AIR model, which demonstrates that the solution of a pinned store using the modified code adequately matches the solution of a translating store using the unmodified code. In addition, extended free flight simulations are conducted in which the dynamic behavior and long term trajectory of the store are observed. The longest simulation lasts for 135 seconds of solution time. Testing of a generic store body with multiple moving fins results in good agreement between the unmodified and modified solution methods. The modified code reduces overall computational cost by 17% for simulations of similar length because of the smaller background mesh. The combination of indefinite runtime and control surface modeling will make Beggar a powerful tool for studying the non-linear dynamic behavior of stores in free flight

Breakdown of Angular Momentum Selection Rules in High Pressure Optical Pumping Experiments

We present measurements, using two complementary methods, of the breakdown of atomic angular momentum selection rules in He-broadened Rb vapor. Atomic dark states are rendered weakly absorbing due to fine-structure mixing during Rb-He collisions. The effect substantially increases the photon demand for optical pumping of dense vapors

Leading-Edge Flutter of Supercavitating Hydrofoils

This paper presents the results of experiments and analysis of the phenomenon of leading-edge flutter which has been observed to occur for supercavitating hydrofoils. The experiments confirmed the existence of such a single-degree-of-freedom flutter involving chordwise bending and indicated that for long, natural (or vapor-filled) cavities the reduced flutter speed, [formula], was in the range 0.15 to 0.23. Secondary effects observed were the variation with the angle of attack (a minimum flutter speed occurred at 10 deg) and with foil mass ratio. Shorter cavities typically yielded lower flutter speeds due to a complex interaction between the bubble collapse process occurring in the cavity closure region and the unsteady hydrodynamic load on the foil. Finally, a relatively simple theoretical analysis for supercavitating hydrofoils with elastic axes aft of midchord is presented. This linear analysis yields reduced flutter velocities somewhat lower than those observed

Analysis of Negative Parity Baryon Photoproduction Amplitudes in the 1/Nc1/N_c Expansion

We study the photoproduction helicity amplitudes of negative parity baryons in the context of the $1/N_c$ expansion of QCD. A complete analysis to next-to-leading order is carried out. The results show sub-leading effects to be within the magnitude expected from the $1/N_c$ power counting. They also show significant deviations from the quark model, in particular the need for 2-body effects.Comment: 7 pages, 5 table

On the role of water‐soluble polypeptides (17, 23 kDa), calcium and chloride in photosynthetic oxygen evolution

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116934/1/feb20014579385800302.pd

Calcium reconstitutes high rates of oxygen evolution in polypeptide depleted Photosystem II preparations

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116911/1/feb20014579384808467.pd

DAMAGE-INDUCED INFLAMMATION AND NOCICEPTIVE HYPERSENSITIVITY IN DROSOPHILA LARVAE

Mounting an effective response to tissue damage requires a concerted effort from a number of systems, including both the immune and nervous systems. Immune-responsive blood cells fight infection and clear debris from damaged tissues, and specialized pain receptors become hypersensitive to promote behavior that protects the damaged area while it heals. To uncover the cellular and molecular mechanisms underlying these processes, we have developed a genetically tractable invertebrate model of damage-induced inflammation and pain hypersensitivity using Drosophila larvae. To study wound-induced inflammation, we generated transgenic larvae with fluorescent epidermal cells and blood cells (hemocytes). Using live imaging, we monitored the circulatory dynamics of hemocytes and the methods by which they accumulate at epidermal wounds. We found that circulating hemocytes attach to wound sites directly from circulation, a mechanism once thought to work exclusively in species with a closed circulatory system. To study damage-induced pain hypersensitivity, we developed a “sunburn assay” and found that larvae have a lowered pain threshold (allodynia) and an exaggerated response to noxious stimuli (hyperalgesia) following UV damage. We screened for genes required for hypersensitivity in pain receptors (nociceptors), and discovered a number of novel mediators that have well conserved mammalian homologs. Together, these results help us to understand how various cell types in the immune and nervous systems both detect and respond to tissue damage