Electropneumatic rheostat regulates high current

Electropneumatic rheostat maintains a constant direct current in each of several high-power parallel loads, of variable resistance, across a single source. It provides current regulation at any preset value by dissipating the proper amount of energy thermally, and uses a column of mercury to vary the effective length of a resistance element

Nonlinear evolution of r-modes: the role of differential rotation

Recent work has shown that differential rotation, producing large scale drifts of fluid elements along stellar latitudes, is an unavoidable feature of r-modes in the nonlinear theory. We investigate the role of this differential rotation in the evolution of the l=2 r-mode instability of a newly born, hot, rapidly rotating neutron star. It is shown that the amplitude of the r-mode saturates a few hundred seconds after the mode instability sets in. The saturation amplitude depends on the amount of differential rotation at the time the instability becomes active and can take values much smaller than unity. It is also shown that, independently of the saturation amplitude of the mode, the star spins down to rotation rates that are comparable to the inferred initial rotation rates of the fastest pulsars associated with supernova remnants. Finally, it is shown that, when the drift of fluid elements at the time the instability sets in is significant, most of the initial angular momentum of the star is transferred to the r-mode and, consequently, almost none is carried away by gravitational radiation.Comment: 10 pages, 5 figure

Predicting the Effects of Contingency Contracting on Local Economies

In recent years, Air Force personnel have been deployed in support of contingency operations to various points on the globe. The Department of Defense spends millions of dollars to support and sustain forces during contingency operations. The Air Force deploys Contingency Contracting Officers (CCO) to support personnel during these operations. During a contingency operation contracting officers will normally establish short-term contracts as quickly as possible to meet mission requirements with little concern for the local economy. This research concluded that the actions of Air Force CCOs can affect the local economy in a deployed location. By providing contingency contracting officers the ability to know how their actions will affect local economies, the AF can mitigate the effect to the local economy while at the same time reducing costs to the Department of Defense

Nucleosynthesis Constraints on Scalar-Tensor Theories of Gravity

We study the cosmological evolution of massless single-field scalar-tensor theories of gravitation from the time before the onset of $e^+e^-$ annihilation and nucleosynthesis up to the present. The cosmological evolution together with the observational bounds on the abundances of the lightest elements (those mostly produced in the early universe) place constraints on the coefficients of the Taylor series expansion of $a(\phi)$, which specifies the coupling of the scalar field to matter and is the only free function in the theory. In the case when $a(\phi)$ has a minimum (i.e., when the theory evolves towards general relativity) these constraints translate into a stronger limit on the Post-Newtonian parameters $\gamma$ and $\beta$ than any other observational test. Moreover, our bounds imply that, even at the epoch of annihilation and nucleosynthesis, the evolution of the universe must be very close to that predicted by general relativity if we do not want to over- or underproduce $^{4}$He. Thus the amount of scalar field contribution to gravity is very small even at such an early epoch.Comment: 15 pages, 2 figures, ReVTeX 3.1, submitted to Phys. Rev. D1

Bargaining in the Shadow of Big Data

Attorney bargaining has traditionally taken place in the shadow of trial as litigants adjust tactics-and their inclination to negotiate a settlement-based on their forecast of the outcome of a trial and its associated costs. Lawyers bargaining on the verge of trial have traditionally relied on their intuition, knowledge of precedent, and previous interactions with the presiding judge and opposing counsel to forecast trial outcomes and litigation costs. Today, however, technology that leverages legal data is moving the practice of law into the shadow of the trends and patterns apparent in aggregated litigation data. This Article describes the tools that facilitate this paradigm shift and examines how lawyers use these tools to forecast litigation outcomes and reduce Coasean bargaining costs in both litigation and transactional fields. This Article also explores some of the risks associated with bargaining in the shadow of big data, and it offers guidance to lawyers leveraging these tools to improve their practice. This discussion pushes beyond the cartoonish image of big data as a mechanical fortuneteller-predicting who will win or lose a case, supposedly eliminating research or deliberation. This Article also debunks the alarmist cliches about newfangled technologies eliminating jobs. Demand for lawyers who are capable of effective bargaining when confronted by big data will continue to increase as the legal profession catches up to the data-centric approach found in other industries. Ultimately, this Article paints a portrait of what big data really means for practicing attorneys, and it provides a framework for exploring the theoretical implications of lawyering in the era of information analytics

Global Disk Oscillation Modes in Cataclysmic Variables and Other Newtonian Accretors

Diskoseismology, the theoretical study of small adiabatic hydrodynamical global perturbations of geometrically thin, optically thick accretion disks around black holes (and other compact objects), is a potentially powerful probe of the gravitational field. For instance, the frequencies of the normal mode oscillations can be used to determine the elusive angular momentum parameter of the black hole. The general formalism developed by diskoseismologists for relativistic systems can be readily applied to the Newtonian case of cataclysmic variables (CVs). Some of these systems (e.g., the dwarf nova SS Cygni) show rapid oscillations in the UV with periods of tens of seconds and high coherence. In this paper, we assess the possibility that these dwarf nova oscillations (DNOs) are diskoseismic modes. Besides its importance in investigating the physical origin of DNOs, the present work could help us to answer the following question. To what extent are the similarities in the oscillation phenomenology of CVs and X-ray binaries (XRBs) indicative of a common physical mechanism?Comment: 1 figur