Near-Infrared Broad-Line Profiles In Low-Redshift QSOs

We present near-infrared and optical spectrophotometry of six low-redshift QSOs. The integrated Pa-alpha/H-alpha-ratios cluster near the value 0.1, with one exception having a larger ratio consistent with other evidence of reddening. At least two of the Pa-alpha/H-alpha-profile ratios decrease with observed velocity. We discuss some implications for the dynamics of the broad-line region and this ratio's usefulness as a reddening indicator. We also present a spectrum of the He I-lambda-10830, Pa-lambda-blend of 1226 + 023. The He I/H-alpha-profile ratio shows marginal evidence for decreasing with observed velocity, which is consistent with the interpretation for the Pa-alpha/H-alpha-profile ratios.NSF 84-14652McDonald Observator

Kinematic analysis of the ARID manipulator

The kinematic structure of the ARID manipulator lends itself to simple forward and inverse kinematics analysis. The purpose of this paper is to fully document and verify an existing analysis. The symbolic software package MATHEMATICA was used to produce and verify the equations presented here. In the analysis to follow, the standard Devenit-Hartenberg kinematic parameters of the ARID were employed

Accretion in giant planet circumplanetary disks

During the final growth phase of giant planets, accretion is thought to be controlled by a surrounding circumplanetary disk. Current astrophysical accretion disk models rely on hydromagnetic turbulence or gravitoturbulence as the source of effective viscosity within the disk. However, the magnetically-coupled accreting region in these models is so limited that the disk may not support inflow at all radii, or at the required rate. Here, we examine the conditions needed for self-consistent accretion, in which the disk is susceptible to accretion driven by magnetic fields or gravitational instability. We model the disk as a Shakura-Sunyaev $\alpha$ disk and calculate the level of ionisation, the strength of coupling between the field and disk using Ohmic, Hall and Ambipolar diffusevities for both an MRI and vertical field, and the strength of gravitational instability. We find that the standard constant-$\alpha$ disk is only coupled to the field by thermal ionisation within $30\,R_J$ with strong magnetic diffusivity prohibiting accretion through the bulk of the midplane. In light of the failure of the constant-$\alpha$ disk to produce accretion consistent with its viscosity we drop the assumption of constant-$\alpha$ and present an alternate model in which $\alpha$ varies radially according to the level magnetic turbulence or gravitoturbulence. We find that a vertical field may drive accretion across the entire disk, whereas MRI can drive accretion out to $\sim200\,R_J$, beyond which Toomre's $Q=1$ and gravitoturbulence dominates. The disks are relatively hot ($T\gtrsim800\,$K), and consequently massive ($M_{\text{disk}}\sim0.5\,M_J$).Comment: 19 pages, 5 figures, 2 tables; accepted for publication by MNRA

Magnetic fields in gaps surrounding giant protoplanets

Giant protoplanets evacuate a gap in their host protoplanetary disc, which gas must cross before it can be accreted. A magnetic field is likely carried into the gap, potentially influencing the flow. Gap crossing has been simulated with varying degrees of attention to field evolution (pure hydrodynamical, ideal, and resistive MHD), but as yet there has been no detailed assessment of the role of the field accounting for all three key non-ideal MHD effects: Ohmic resistivity, ambipolar diffusion, and Hall drift. We present a detailed investigation of gap magnetic field structure as determined by non-ideal effects. We assess susceptibility to turbulence induced by the magnetorotational instability, and angular momentum loss from large-scale fields. As full non-ideal simulations are computationally expensive, we take an a posteriori approach, estimating MHD quantities from the pure hydrodynamical gap crossing simulation by Tanigawa et al. (2012). We calculate the ionisation fraction and estimate field strength and geometry to determine the strength of non-ideal effects. We find that the protoplanetary disc field would be easily drawn into the gap and circumplanetary disc. Hall drift dominates, so that much of the gap is conditionally MRI unstable depending on the alignment of the field and disc rotation axes. Field alignment also influences the strong toroidal field component permeating the gap. Large-scale magnetic forces are small in the circumplanetary disc, indicating they cannot drive accretion there. However, turbulence will be key during satellite growth as it affects critical disc features, such as the location of the ice line.Comment: 14 pages, 6 figures, accepted for publication by MNRA

Possible biomedical applications and limitations of a variable-force centrifuge on the lunar surface: A research tool and an enabling resource

Centrifuges will continue to serve as a valuable research tool in gaining an understanding of the biological significance of the inertial acceleration due to gravity. Space- and possibly lunar-based centrifuges will play a significant and enabling role with regard to the human component of future lunar and martian exploration, both as a means of accessing potential health and performance risks and as a means of alleviating these risks. Lunar-based centrifuges could be particularly useful as part of a program of physiologic countermeasures designed to alleviate the physical deconditioning that may result from prolonged exposure to a 1/6-g environment. Centrifuges on the lunar surface could also be used as part of a high-fidelity simulation of a trip to Mars. Other uses could include crew readaptation to 1 g, waste separation, materials processing, optical mirror production in situ on the Moon, and laboratory specimen separation

Admiralty Litigation In Perpetuum: The Continuing Saga of Package Litigation and Third World Delivery Problems

Certain admiralty cargo issues are litigated frequently, often in search of a magical test which will preclude all further litigation. Three such issues are package limitations, the burden of proving the condition and quantity of cargo stowed within containers, and the point at which the ocean carrier delivers cargo at discharge and thus completes its duties under the contract of carriage. Despite the frequency with which these issues have been litigated, significant disagreement remains among the circuit courts as to their proper resolution. This article will examine the current state of judicial uncertainty in these areas and the indications given by the courts as the positions most likely to be adopted in the future

Matanuska Valley Memoir

We acknowledge indebtedness to the historians and developers of Alaskana who preceded us and provided much of the information we have compiled into our account of the birth of a community. Many "old timers" from the Valley provided valuable insight into situations they had experienced. Mr. Roland Snodgrass, Mrs, June Murphy and Miss Dolores Pommier assisted in compilation and preparation of background data. Mr. James Hurley made available to us the ARRC unpublished files for compilation of certain data. Various public officials aided us in many ways as we worked· our way through recorded . history. Several old photos were contributed by Mr. Walter Teeland of Wasilla and Mr. Don L. Irwin of Palmer. Several persons in public and private life who know Alaskan conditions have reviewed the manuscript and suggested improvements, Special acknowledgement is due Don L. Irwin, Director of the Alaska Agricultural Experiment Station, His vision and foresight were largely responsible for the undertaking, His encouragement and advice bolstered our lagging spirits before the long task was completed. He has read each chapter critically and has assisted particularly with interpretation of materials since 1935,The Matanuska Valley was created through action of ice, water and wind. When the last glaciers retreated up the Susitna, the Knik and the Matanuska valleys, vegetation began cove ring the scars, Over several centuries a dense growth of trees and brush screened the land from Knik Arm to the mountain slopes of the Talkeetna range . Here and there a lake broke the uniform forest mantle. A salt marsh at the mouth of the Matanuska River kept the rank undergrowth from reaching tide water, A few low spots near the Little Susitna and other swampy areas supported a thick cover of moss or grass. The Valley, which really isn't a valley at all but a reworked foreland, rises from the Matanuska River in a series of benches ranging in width from a few hundred feet to more than a mile. Some areas are flat, others are rolling. Soil depth varies from eight feet in thickness for the region bordering the Matanuska River to a few inches in sections west of Wasilla. The soil mantle, of windblown loessial materials, is of relatively new geologic development, The Valley is bounded by the Chugach Mountains on the east, the Talkeetnas on the north, the Susitna Valley on the west and Knik Arm on the south. Winters are long but usually not unduly severe; summers cool and relatively moist, To this country came trappers, prospectors and traders in closing years of the nineteenth century. Hordes of insects, difficult trails, sparse population and great distance s from supply points discouraged many potential residents, Those who stayed were interested primarily in the Willow Creek gold field or the Matanuska coal deposits. Another generation, an uneasy international situation and social crises within the United States were required before the Matanuska Valley and the rest of Upper Cook Inlet were ripe for use. This history of the Valley is designed to trace the many human elements affecting the ebb and flow of agricultural development here. It brings into focus many problems that must be solved before new areas in Alaska can be settled satisfactorily

Implications of the r-mode instability of rotating relativistic stars

Several recent surprises appear dramatically to have improved the likelihood that the spin of rapidly rotating, newly formed neutron stars (and, possibly, of old stars spun up by accretion) is limited by a nonaxisymmetric instability driven by gravitational waves. Except for the earliest part of the spin-down, the axial l=m=2 mode (an r-mode) dominates the instability, and the emitted waves may be observable by detectors with the sensitivity of LIGO II. A review of these hopeful results is followed by a discussion of constraints on the instability set by dissipative mechanisms, including viscosity, nonlinear saturation, and energy loss to a magnetic field driven by differential rotation.Comment: 20 pages LaTeX2e (stylefile included), 6 eps figures. Review to appear in the proceedings of the 9th Marcel Grossman Meeting, World Scientific, ed. V. Gurzadyan, R. Jantzen, R. Ruffin