Pulsar Kicks Induced by Spin Flavor Oscillations of Neutrinos in Gravitational Fields

The origin of pulsar kicks is reviewed in the framework of the spin-flip conversion of neutrinos propagating in the gravitational field of a magnetized protoneutron star. We find that for a mass in rotation with angular velocity {\bbox \omega}, the spin connections entering in the Dirac equation give rise to the coupling term {\bbox \omega}\cdot {\bf p}, being ${\bf p}$ the neutrino momentum. Such a coupling can be responsible of pulsar kicks owing to the neutrino emission asymmetry generated by the relative orientation of ${\bf p}$ with respect to {\bbox \omega}. For our estimations, the large non standard neutrino magnetic momentum, $\mu_\nu \lesssim 10^{-11}\mu_B$, is considered.Comment: 8 pages, no figures. Changed content and references adde

Electromechanical systems with transient high power response operating from a resonant AC link

The combination of an inherently robust asynchronous (induction) electrical machine with the rapid control of energy provided by a high frequency resonant AC link enables the efficient management of higher power levels with greater versatility. This could have a variety of applications from launch vehicles to all-electric automobiles. These types of systems utilize a machine which is operated by independent control of both the voltage and frequency. This is made possible by using an indirect field-oriented control method which allows instantaneous torque control in all four operating quadrants. Incorporating the AC link allows the converter in these systems to switch at the zero crossing of every half cycle of the AC waveform. This zero loss switching of the link allows rapid energy variations to be achieved without the usual frequency proportional switching loss. Several field-oriented control systems were developed by LeRC and General Dynamics Space Systems Division under contract to NASA. A description of a single motor, electromechanical actuation system is presented. Then, focus is on a conceptual design for an AC electric vehicle. This design incorporates an induction motor/generator together with a flywheel for peak energy storage. System operation and implications along with the associated circuitry are addressed. Such a system would greatly improve all-electric vehicle ranges over the Federal Urban Driving Cycle (FUD)

Numerical Toy-Model Calculation of the Nucleon Spin Autocorrelation Function in a Supernova Core

We develop a simple model for the evolution of a nucleon spin in a hot and dense nuclear medium. A given nucleon is limited to one-dimensional motion in a distribution of external, spin-dependent scattering potentials. We calculate the nucleon spin autocorrelation function numerically for a variety of potential densities and distributions which are meant to bracket realistic conditions in a supernova core. For all plausible configurations the width of the spin-density structure function is found to be less than the temperature. This is in contrast with a naive perturbative calculation based on the one-pion exchange potential which overestimates the width and thus suggests a large suppression of the neutrino opacities by nucleon spin fluctuations. Our results suggest that it may be justified to neglect the collisional broadening of the spin-density structure function for the purpose of estimating the neutrino opacities in the deep inner core of a supernova. On the other hand, we find no indication that processes such as axion or neutrino pair emission, which depend on nucleon spin fluctuations, are substantially suppressed beyond the multiple-scattering effect already discussed in the literature. Aside from these practical conclusions, our model reveals a number of interesting and unexpected insights. For example, the spin-relaxation rate saturates with increasing potential strength only if bound states are not allowed to form by including a repulsive core. There is no saturation with increasing density of scattering potentials until localized eigenstates of energy begin to form.Comment: 14 latex pages in two-column format, 15 postscript figures included, uses revtex.sty and epsf.sty. Submitted to Physical Review

Information Management in the Modern Hydrographic Office - A Challenge for the 21st Century

Collectively, the various national hydrographic authorities within the auspices of the International Hydrographic Organization (IHO) are the custodians of a significant portion of the world asset of marine information. In the course of managing this information, Member States have been subject to significant changes in both technology and user requirements. The current practices that have evolved to provide a relatively uniform service of charts and other publications for the international mariner are today under increasing pressure to adapt to a wider variety of specific user needs and the methodologies for presentation. Consideration must be given as to whether the current information management practices in place today are able to meet the source data capabilities and user requirements of tomorrow. This paper discusses a rationale for the structuring that may bë required for future hydrographic information management. It examines current problems and some potential directions in the overall management and organization of the types of information held by the modem hydrographic agency. An appreciation and understanding of the issues surrounding information management in hydrographic organizations, under the auspices of the International Hydrographic Organization, must lead to a closer cooperation towards meeting the challenge of international information dissemination in the twenty-first century

The Logistics of Mobilizing and Supplying the Union Army during the Initial Stages of the American Civil War

This thesis studies the logistics involved in mobilizing and supplying the Union Army at the onset of the Civil War. The main elements discussed are the sources, procedures, and items needed for the mobilization and supply efforts. Initially, the Union relied on the States to mobilize the military with the majority of the military being militia members or volunteers. The number of volunteers declined later in the war and the Union used both the bounty system and the draft for recruitment. Eventually, the Federal Government replaced the States as the primary mobilizing entity. The military needed supplies of weapons, clothing, and food. Again the States were the primary providers of supplies. The Union later used domestic and foreign markets for supplies, but the urgency of the nation spawned fraud and corruption. Additionally, the majority of the supplies provided were not adequate for the environment of war. By the end of war, corruption decreased and quality increased. Today\u27s military can use the actions of the Union as guidance of what to do and what not to do in the time of war. The actions of the Union during the Civil War should be used as a template for future generations

Accumulation of heavy metals by organisms in the Derwent catchment

The distribution of Zn, Cd and Pb in water, sediments, plants and animals from the River Derwent and Derwent Reservoir was studied during four periods of intensive survey between October 197 8 and November 1979.Elevated concentrations of Zn, Cd and Pb were found in all components from the river below the entry of a polluted tributary, Bolts Burn. Concentrations of Zn in river sediments from above Bolts Burn and Zn and Cd from below were found to show significant positive correlations with the organic content of sediments. It is suggested that autumn shed leaves may exert considerable influence on the metal composition of river sediments during decomposition and may cause an increase in the amount of metal potentially available to detritivorous invertebrates in their food. Marked variations were observed in concentrations of Zn, Cd and Pb in plants and animals from the river between reaches and surveys. Among the animals, mayflies as a group had especially high concentrations of metals and Zn, Cd and Pb were frequently higher in samples of these from the river above Bolts Burn than in many other animals from below this stream. Metal pollution was shown to extend into the Derwent Reservoir. Elevated concentrations of Zn and Pb evident in water, sediments and submerged plants near the entry of the river were found to decrease on passing towards the dam. Comparisons between metal concentrations in the biota and those in their environment made it possible to assess possible importance of water and sediments as sources from which metals may be accumulated

Theoretical Interpretation of the Measurements of the Secondary Eclipses of TrES-1 and HD209458b

We calculate the planet-star flux-density ratios as a function of wavelength from 0.5 microns to 25 microns for the transiting extrasolar giant planets TrES-1 and HD209458b and compare them with the recent Spitzer/IRAC-MIPS secondary eclipse data in the 4.5, 8.0, and 24 micron bands. With only three data points and generic calibration issues, detailed conclusions are difficult, but inferences regarding atmospheric composition, temperature, and global circulation can be made. Our models reproduce the observations reasonably well, but not perfectly, and we speculate on the theoretical consequences of variations around our baseline models. One preliminary conclusion is that we may be seeing in the data indications that the day side of a close-in extrasolar giant planet is brighter in the mid-infrared than its night side, unlike Jupiter and Saturn. This correspondence will be further tested when the data anticipated in other Spitzer bands are acquired, and we make predictions for what those data may show.Comment: 15 pages, including 3 color figures, submitted to the Astrophysical Journa