On the Spinning Motion of the Hovering Magnetic Top

In this paper we analyze the spinning motion of the hovering magnetic top. We have observed that its motion looks different from that of a classical top. A classical top rotates about its own axis which precesses around a vertical fixed external axis. The hovering magnetic top, on the other hand, has its axis slightly tilted and moves rigidly as a whole about the vertical axis. We call this motion synchronous, because in a stroboscopic experiment we see that a point at the rim of the top moves synchronously with the top axis. We show that the synchronous motion may be attributed to a small deviation of the magnetic moment from the symmetry axis of the top. We calculate the minimum angular velocity required for stability in terms of the moments of inertia and magnetic field and show that it is different from that of a classical top. We also give experimental results that were taken with a top whose moment of inertia can be changed. These results show very good agreement with our calculations.Comment: 19 pages (including 3 figures named fig1.eps-fig3.eps), uses amssymb, epsf and amsbsy (AMSLaTeX

Application of Advanced Reservoir Characterization, Simulation and Production Optimization Strategies to Maximize Recovery in Slope and Basin Clastic Reservoirs, West Texas (Delaware Basin)

The objective of this Class III project is to demonstrate that detailed reservoir characterization of slope and basin elastic reservoirs in sandstones of the Delaware Mountain Group in the Delaware Basin of West Texas and New Mexico is a cost-effective way to recover oil more economically through geologically based field development. The project is focused on East Ford, a Delaware Mountain Group field that produces from the upper Bell Canyon Formation (Ramsey sandstone). The field, discovered in 1960, is operated by Orla Petco, Inc., as the East Ford unit. A CO2 flood is being conducted in the unit, and this flood is the Phase 2 demonstration for the project. Reservoir characterization was conducted using logs and pressure and production information from the East Ford unit, supplemented by Bell Canyon outcrop data and information from the nearby Geraldine Ford field. Characterization was enhanced this year by recovery of a core from the Ramsey reservoir interval in the EFU 41R well. Ramsey sandstones are interpreted as having been deposited in a basin-floor setting in a channel-levee system with attached lobes. Overbank splays are interpreted as being the main area of sand storage outside of the channels. Porosity and permeability of the reservoir sandstones are controlled by calcite cement that can be concentrated in layers ranging from 5 to 40 cm in thickness. These laterally extensive calcite-cemented layers form significant vertical permeability baffles in some areas of the reservoir.Bureau of Economic Geolog

Photon deflection and precession of the periastron in terms of spatial gravitational fields

We show that a Maxwell-like system of equations for spatial gravitational fields $\bf g$ and $\bf B$ (latter being the analogy of a magnetic field), modified to include an extra term for the $\bf B$ field in the expression for force, leads to the correct values for the photon deflection angle and for the precession of the periastron

Variation in Establishment Success for American Mistletoe [\u3ci\u3ePhoradendron leucarpum\u3c/i\u3e (Raf.) Reveal & M.C. Johnst. (Viscaceae)] Appears Most Likely to Predict its Distribution in Virginia and North Carolina, United States

Dispersal limitation and variation in habitat suitability may determine an association of American mistletoe [Phoradendron leucarpum (Raf.) Reveal & M.C. Johnst. (Viscaceae)] with forested wetlands in Virginia and North Carolina, United States. Here, we first tested the alternative hypothesis that variation in host availability drives this habitat relationship. We used a generalized linear model to show a positive effect of forested wetland habitat on American mistletoe occurrence after accounting for both variation in host availability and differences among regions in host use. We then used seed sowing experiments to quantify how light availability and flood regime determine the viability of American mistletoe, allowing us to evaluate the potential for establishment limitation to determine this habitat relationship. Light availability predicted establishment rates but % canopy openness did not predict seed germination rates. Thus, variation in the ability for American mistletoe to establish across forested habitat types with different local light availabilities is a potentially important mechanism in determining its distribution

Magnetic Properties of Magnetotactic Bacteria

This paper reports on the magnetic properties of magnetosomes in the freshwater magnetotactic bacterium Aquaspirillum magnetotacticum. The magnetosomes are well crystallized particles of magnetite with dimensions of 40 to 50 nm, which are arranged within the cells in a single linear chain and are within the single-magnetic-domain (SD) size range for magnetite. A variety of magnetic properties have been measured for two samples of dispersions of freeze-dried cells consisting of (1) whole cells (M-1) and (2) magnetosomes chains separated from cells (M-2). An important result is that the acquisition and demagnetization of various type of remanent magnetizations are markedly different for the two samples and suggest that remanence is substantially affected by magnetostatic interactions. Interactions are likely to be much more important in M-2 because the extracted magnetosome chains are no longer separated from one another by the cell membrane and cytoplasm. Other experimental data for whole cells agree with predictions based on the chain of spheres model for magnetization reversal. This model is consistent with the unique linear arrangement of equidimensional particles in A. magnetotacticum. The magnetic properties of bacterial and synthetic magnetites are compared and the paleomagnetic implications are discussed

Patient engagement with antibiotic messaging in secondary care: a qualitative feasibility study of the ‘review & revise’ experience

Background: We aimed to investigate and optimise the acceptability and usefulness of a patient leaflet about antibiotic prescribing decisions made during hospitalisation, and to explore individual patient experiences and preferences regarding the process of antibiotic prescription ‘review & revise’ which is a key strategy to minimise antibiotic overuse in hospitals. Methods: In this qualitative study, run within the feasibility study of a large, cluster-randomised stepped wedge trial of 36 hospital organisations, a series of semi-structured, think-aloud telephone interviews were conducted and data were analysed using thematic analysis. Fifteen adult patients who had experienced a recent acute medical hospital admission during which they had been prescribed antimicrobials and offered a patient leaflet about antibiotic prescribing were recruited to the study. Results: Participants reacted positively to the leaflet, reporting that it was both an accessible and important source of information which struck the appropriate balance between informing and reassuring. Participants all valued open communication with clinicians, and were keen to be involved in antibiotic prescribing decisions, with individuals reporting positive experiences regarding antibiotic prescription changes or stopping. Many participants had prior experience or knowledge of antibiotics and resistance, and generally welcomed efforts to reduce antibiotic usage. Overall, there was a feeling that healthcare professionals (HCPs) are trusted experts providing the most appropriate treatment for individual patient conditions. Conclusions: This study offers novel insights into how patients within secondary care are likely to respond to messages advocating a reduction in the use of antibiotics through the ‘review & revise’ approach. Due to the level of trust that patients place in their care provider, encouraging HCPs within secondary care to engage patients with greater communication and information provision could provide great advantages in the drive to reduce antibiotic use. It may also be beneficial for HCPs to view patient experiences as cumulative events that have the potential to impact future behaviour around antibiotic use. Finally, pre-testing messages about antibiotic prescribing and resistance is vital to dispelling any misconceptions either around effectiveness of treatment for patients, or perceptions of how messages may be received

Microscopic Structure of the Calcium Isotopes

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

Forces at Individual Pseudopod-Filament Adhesive Contacts

On-chip cellular force sensors are fabricated from cantilever poly(3,4-ethylene dioxythiophene) filaments that visibly deflect under forces exerted at individual pseudopod-filament adhesive contacts. The shape of the deflected filaments and their ∼3 nN/μm spring constants are predicted by cantilever rod theory. Pulling forces exerted by Dictyostelium discoideumcells at these contacts are observed to reach ∼20 nN without breaking the contact