POWER DEVELOPED BY THE MIDFOOT JOINT DURING RUNNING WITH AND WITHOUT SHOES

The purpose of this study was to remedy the lack of knowledge about the function of the midfoot joint during the propulsion phase of running and to assess the effect of footwear on this function compared to running barefoot. A valid model of the rearfoot was identified and 12 healthy male subjects performed five trials each of running with and without shoes while data was collected with a ten-camera and single force plate motion capture system. Analysis of the results showed that the midfoot joint generated 39% of total power from the foot region during barefoot running. This reduced to 25% when shoe-wearing as a result of a reduction in range of motion at the midfoot joint. The findings may have implications for running efficiency and injury but both these conjectures need further study

Hard x-ray polarimetry with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI)

Although designed primarily as a hard X-ray imager and spectrometer, the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) is also capable of measuring the polarization of hard X-rays (20-100 keV) from solar flares. This capability arises from the inclusion of a small unobstructed Be scattering element that is strategically located within the cryostat that houses the array of nine germanium detectors. The Ge detectors are segmented, with both a front and rear active volume. Low energy photons (below about 100 keV) can reach a rear segment of a Ge detector only indirectly, by scattering. Low energy photons from the Sun have a direct path to the Be and have a high probability of Compton scattering into a rear segment of a Ge detector. The azimuthal distribution of these scattered photons carries with it a signature of the linear polarization of the incident flux. Sensitivity estimates, based on simulations and in-flight background measurements, indicate that a 20-100 keV polarization sensitivity of less than a few percent can be achieved for X-class flares

Marion: You\u27ll Soon Be Marryin\u27 Me

https://digitalcommons.library.umaine.edu/mmb-vp/2090/thumbnail.jp

Idempotent ideals and non-finitely generated projective modules over integral group rings of polycyclic-by-finite groups

We prove that every non-finitely generated projective module over the integral group ring of a polycyclic-by-finite group G is free if and only if G is polycyclic.Comment: 15 pages, to appear in J. Algebr

Collective state measurement of mesoscopic ensembles with single-atom resolution

For mesoscopic ensembles containing 100 or more atoms we measure the total atom number and the number of atoms in a specific hyperfine state with single-atom resolution. The measurement detects the atom-induced shift of the resonance frequency of an optical cavity containing the ensemble. This work extends the range of cavity-based detection with single-atom resolution by more than an order of magnitude in atom number, and provides the readout capability necessary for Heisenberg-limited interferometry with atomic ensembles.Comment: 5 pages, 4 pdf figure

D-modules on Smooth Toric Varieties

Let X be a smooth toric variety. David Cox introduced the homogeneous coordinate ring S of X and its irrelevant ideal B. Extending well-known results on projective space, Cox established the following: (1) the category of quasi-coherent sheaves on X is equivalent to the category of graded S-modules modulo B-torsion, (2) the variety X is a geometric quotient of Spec(S) V(B) by a suitable torus action. We provide the D-module version of these results. More specifically, let A denote the ring of differential operators on Spec(S). We show that the category of D-modules on X is equivalent to a subcategory of graded A-modules modulo B-torsion. Additionally, we prove that the characteristic variety of a D-module is a geometric quotient of an open subset of the characteristic variety of the associated A-module and that holonomic D-modules correspond to holonomic A-modules.Comment: AMS-LaTeX, 28 page

Nonsolar astronomy with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)

The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) is a NASA Small Explorer satellite designed to study hard x-ray and gamma-ray emission from solar flares. In addition, its high-resolution array of germanium detectors can see photons from high-energy sources throughout the Universe. Here we discuss the various algorithms necessary to extract spectra, lightcurves, and other information about cosmic gamma-ray bursts, pulsars, and other astrophysical phenomena using an unpointed, spinning array of detectors. We show some preliminary results and discuss our plans for future analyses. All RHESSI data are public, and scientists interested in participating should contact the principal author

Unruffled extensions and flatness over central subalgebras

A condition on an affine central subalgebra $Z$ of a noetherian algebra $A$ of finite Gelfand-Kirillov dimension, which we call here \emph{unruffledness}, is shown to be equivalent in some circumstances to the flatness of $A$ as a $Z$-module. Unruffledness was studied by Borho and Joseph in work on enveloping algebras of complex semisimple Lie algebras, and we discuss applications of our result to enveloping algebras, as well as beginning the study of this condition for more general algebras

School Administrator and Staff Member Perceptions of a Teenage Pregnancy Prevention Program

Mississippi is among the states with the highest teenage pregnancy rates, and the study site is among the high schools with the highest teenage pregnancy rates in the state. The purpose of this qualitative case study was to identify successful practices and areas for improvement in the implementation of a teenage pregnancy prevention program (TPPP) at the study site based on the perspectives of school administrators and staff members. Bandura\u27s social cognitive theory provided a conceptual framework for considering behaviors and the social contexts in which they occur. Twelve participants were interviewed, including 3 administrators and 9 staff members. Data were analyzed using open coding to identify themes. Findings indicated that, according to the perspectives of the 12 participants, the evidence-based TPPP positively influenced the students by providing a structured curriculum for classroom teaching; promoting small-group discussions; and implementing an abstinence approach to prevent teenage pregnancy, HIV, and STDs. Strengths identified included the use of various instructional techniques and a general support for communication. Areas for improvement included scheduling, school staff and parent buy-in, and knowledge about specific problems related to risk-taking behaviors. Social change implications of this study include increased awareness among adult stakeholders of practices that support successful implementation of a TPPP and enhanced ability to make positive decisions about sexual behaviors among students. School officials could apply the findings to strengthening the effectiveness of the school\u27s TPPP. Students may benefit from improved TPPP instruction by being better prepared to prevent teenage pregnancy, HIV, and STDs