Realization of a Resonant Fermi Gas with a Large Effective Range

We have measured the interaction energy and three-body recombination rate for a two-component Fermi gas near a narrow Feshbach resonance and found both to be strongly energy dependent. Even for deBroglie wavelengths greatly exceeding the van der Waals length scale, the behavior of the interaction energy as a function of temperature cannot be described by atoms interacting via a contact potential. Rather, energy-dependent corrections beyond the scattering length approximation are required, indicating a resonance with an anomalously large effective range. For fields where the molecular state is above threshold, the rate of three-body recombination is enhanced by a sharp, two-body resonance arising from the closed-channel molecular state which can be magnetically tuned through the continuum. This narrow resonance can be used to study strongly correlated Fermi gases that simultaneously have a sizeable effective range and a large scattering length.Comment: to appear in Phys. Rev. Let

Differential Growth of Francisella tularensis, Which Alters Expression of Virulence Factors, Dominant Antigens, and Surface-carbohydrate Synthases, Governs the Apparent Virulence of Ft Schus4 to Immunized Animals

The gram-negative bacterium Francisella tularensis (Ft) is both a potential biological weapon and a naturally occurring microbe that survives in arthropods, fresh water amoeba, and mammals with distinct phenotypes in various environments. Previously, we used a number of measurements to characterize Ft grown in Brain-Heart Infusion (BHI) broth as (1) more similar to infection-derived bacteria, and (2) slightly more virulent in naive animals, compared to Ft grown in Mueller Hinton Broth (MHB). In these studies we observed that the free amino acids in MHB repress expression of select Ft virulence factors by an unknown mechanism. Here, we tested the hypotheses that Ft grown in BHI (BHI-Ft) accurately displays a full protein composition more similar to that reported for infection-derived Ft and that this similarity would make BHI-Ft more susceptible to pre-existing, vaccine-induced immunity than MHB-Ft. We performed comprehensive proteomic analysis of Ft grown in MHB, BHI, and BHI supplemented with casamino acids (BCA) and compared our findings to published omics data derived from Ft grown in vivo. Based on the abundance of ~1,000 proteins, the fingerprint of BHI-Ft is one of nutrient-deprived bacteria that-through induction of a stringent-starvation-like response-have induced the FevR regulon for expression of the bacterium\u27s virulence factors, immuno-dominant antigens, and surface-carbohydrate synthases. To test the notion that increased abundance of dominant antigens expressed by BHI-Ft would render these bacteria more susceptible to pre-existing, vaccine-induced immunity, we employed a battery of LVS-vaccination and S4-challenge protocols using MHB- and BHI-grown Ft S4. Contrary to our hypothesis, these experiments reveal that LVS-immunization provides a barrier to infection that is significantly more effective against an MHB-S4 challenge than a BHI-S4 challenge. The differences in apparent virulence to immunized mice are profoundly greater than those observed with primary infection of naive mice. Our findings suggest that tularemia vaccination studies should be critically evaluated in regard to the growth conditions of the challenge agent

Exploring NIRSA Championship Series Professional Development Opportunities: Understanding Their Perceived Value to the Association

The NIRSA Championship Series (Series) is a significant component of NIRSA: Leaders in Collegiate Recreation (NIRSA). Demonstrated, in part, by the fact that many campus recreational professionals contend the events directly relate to both their institution and the association’s mission. The purpose of this study was to gain an understanding of how NIRSA professionals perceive the value of volunteer experiences at Series events. The research team conducted semistructured interviews with thirteen campus recreation directors. The participants had a median of 28 years in the profession, (SD = 7.4), and represented all six NIRSA regions. In describing the benefits of volunteerism at Series events, the directors identified three broad themes, each with numerous subthemes: Personal Experience (Lifelong learner, Mentors, and Networking), Professional Development (Teamwork, Leadership, Communication, and Training), andIdeal Job Characteristics (Attitude and Organizational Citizenship Behaviors). The themes, subthemes, and implications for Series events are discussed. In addition, the authors present suggestions for future research

Three-body recombination in a three-state Fermi gas with widely tunable interactions

We investigate the stability of a three spin state mixture of ultracold fermionic $^6$Li atoms over a range of magnetic fields encompassing three Feshbach resonances. For most field values, we attribute decay of the atomic population to three-body processes involving one atom from each spin state and find that the three-body loss coefficient varies by over four orders of magnitude. We observe high stability when at least two of the three scattering lengths are small, rapid loss near the Feshbach resonances, and two unexpected resonant loss features. At our highest fields, where all pairwise scattering lengths are approaching $a_t = -2140 a_0$, we measure a three-body loss coefficient $L_3 \simeq 5\times 10^{-22} \mathrm{cm}^6/\mathrm{s}$ and a trend toward lower decay rates for higher fields indicating that future studies of color superfluidity and trion formation in a SU(3) symmetric Fermi gas may be feasible

NIRSA Championship Series Volunteerism: The Perceived Impact on Professional Development

The National Intramural-Recreational Sports Association (NIRSA) Championship Series (Series) has developed into the primary organization for governing extramural/sport club collegiate recreational tournaments. As NIRSA professionals describe it, the Series has also evolved into a platform for professional development. To date, however, no study has attempted to link professional growth and advancement to volunteerism at Series events. As such, the purpose of this study was to examine skills and competencies that could be correlated with volunteering at Series events. Using Astin’s Input-Environment-Outcome (I-E-O) model the research team explored the environmental impact of the volunteer experience by collecting data in two phases (prevolunteer experience and 3–4 months after the volunteer experience). Results indicated that campus recreation professionals do perceive themselves to be using effective leadership and communication behaviors and that there are no significant differences in professional development based on the NIRSA region of the tournament. Some gendered differences were uncovered, but it appears that a significant number of volunteers returned to work with higher levels of job-related competencies and important networking connections. Possible implications are discussed, including a Series training program based on NIRSA’s core competencies, and areas for future research

Multi-Object Analysis of Volume, Pose, and Shape Using Statistical Discrimination

One goal of statistical shape analysis is the discrimination between two populations of objects. Whereas traditional shape analysis was mostly concerned with studying single objects, analysis of multi-object complexes presents new challenges related to alignment and relative object pose. In this paper, we present a methodology for discriminant analysis of sets multiple shapes. Shapes are represented by sampled medial manifolds including normals to the boundary. Non-Euclidean metrics that describe geodesic distance between sets of sampled representations are used for shape alignment and discrimination. Our choice of discriminant method is the distance weighted discriminant (DWD) because of its generalization ability in high dimensional, low sample size settings. Using an unbiased, soft discrimination score we can associate a statistical hypothesis test with the discrimination results. Furthermore, localization and nature significant differences between populations can be visualized via the average best discriminating axis

Mating success of male hermit crabs in shell generalist and shell specialist species

The reproductive behavior of two species of diogenid hermit crabs was studied in Hawaii. In the shell generalist, Clibanarius zebra , male reproductive success varied little with size, although the largest males were less successful in obtaining copulations than were medium-large males. Male and female size were positively correlated, in successful pairs, thus larger males had the potential to fertilize more eggs when they were successful in obtaining a copulation. Female fecundity in C. zebra was not affected by species of gastropod shell inhabited once female size was taken into account. Male copulatory success was very strongly influenced by the species of gastropod shell inhabited. Males in Trochus or Nerita shells had greatly reduced reproductive success compared to males in Turbo or Nassarius shells. This result was due both to (1) males in Trochus especially dropping and otherwise poorly handling females during precopulatory behavior and (2) females not responding to precopulatory behavior patterns executed by males in Trochus and Nerita . Transferring males from “good” to “bad” shapes of shells and vice versa showed that male success was a function of shell type inhabited and not some correlated feature of the crabs. In the shell specialist, Calcinus seurati , which is found primarily in Nerita shells as an adult, males in Nerita shells were quite successful in obtaining copulations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46893/1/265_2004_Article_BF00302928.pd