Accretion, Outflows, and Winds of Magnetized Stars

Many types of stars have strong magnetic fields that can dynamically influence the flow of circumstellar matter. In stars with accretion disks, the stellar magnetic field can truncate the inner disk and determine the paths that matter can take to flow onto the star. These paths are different in stars with different magnetospheres and periods of rotation. External field lines of the magnetosphere may inflate and produce favorable conditions for outflows from the disk-magnetosphere boundary. Outflows can be particularly strong in the propeller regime, wherein a star rotates more rapidly than the inner disk. Outflows may also form at the disk-magnetosphere boundary of slowly rotating stars, if the magnetosphere is compressed by the accreting matter. In isolated, strongly magnetized stars, the magnetic field can influence formation and/or propagation of stellar wind outflows. Winds from low-mass, solar-type stars may be either thermally or magnetically driven, while winds from massive, luminous O and B type stars are radiatively driven. In all of these cases, the magnetic field influences matter flow from the stars and determines many observational properties. In this chapter we review recent studies of accretion, outflows, and winds of magnetized stars with a focus on three main topics: (1) accretion onto magnetized stars; (2) outflows from the disk-magnetosphere boundary; and (3) winds from isolated massive magnetized stars. We show results obtained from global magnetohydrodynamic simulations and, in a number of cases compare global simulations with observations.Comment: 60 pages, 44 figure

Historical Analysis of the U.S. Oyster Market with Emphasis on the Role of Imports

The U.S. oyster supply has experienced a substantial change in its composition. Since 1950 total'oyster imports have more. than tripled, with most of this increase coming from Japan. Imports now account for 23 percent of total U.S. supply. The Pacific Coast receives nearly 60 percent of all U.S. imports and the Atlantic and Gulf Coasts receive approximately 18 percent each. The U.S. oyster industry has been beset by a number of problems. These problems include an antiquated regulatory structure, competition for the resource base, pollution, MSX disease, stagnant technology, declining consumption and imports. As a result the trend in annual harvests has shown a considerable decrease since 1950, particularly in middle Atlantic States where it decreased from 18 to 2 million pounds in only 19 years. Harvesting techniques and ownership patterns are also examined and decreased use of dredges and private oyster grounds are noted. All of these problems affecting the oyster industry have affected profits. To fully understand the role of imports in their effect on profits other determinants of profitability must also be measured. Independent of these other problems, however, imports are shown to have had a measurable impact in some instances in the Gulf and the Pacific region

Discussions and Research on Ocean Fishery Management: A Summary of U.S. Workshop

In November of 1970 the U.S. National Marine Fisheries Service, its Division of Economic Research, held a subject workshop which was attended by 60 persons from broad research backgrounds, including representatives from the British Whitefish Authority, the ORganization fro Economic Co-operation and Development, and Food and Agricultural Fisheries and Forestry, as well as representatives of U.S. government agencies and universities. Research topics ranged from production economics and bio-economic models to general discussions of management for both conservation and economic purposes, the political framework involved. This paper summarizes the key issues in the 16 papers presented at that Workshop and the discussions that resulted. The highlights of these issues are presented to this symposium in the form of suggested critical problems which must urgently be faced by the professionals gathered here

The Domain of Population Dynamics and Production Economcis in Fisheries Management Research

With growing conceptual acceptability of fishery management techniques which advocate the reduction in the number of units of effort applied to overexploited and/or overcapitalized fisheries it is increasingly necessary that some readily usable measures be developed whihc may serve all those involved in fishery management and supporting research. Toward this end this paper examines the foundations of measures of fishing effort and fishing power as conceived within the domains of population dynamics and production economics. The degree to whiche ach discipline generates different and mutually exclusive measures is examined, along with an attempt to delineate a separate and distinct role for each discipline within the overall process of generating supporting information needed in all generalized fishery management plan

A Price Incentive Plan for Distressed Fisheries

Many regional fisheries have reached crossroads and decisions must be made. Vast untapped resources exist as a potential foundation for a revitalized fishery. In addition, there exists available unemployed labor and capital in harvesting, processing, and marketing. As many of the traditional fisheries must continue at a low level due to an array of circumstances, we propose to encourage the transfer of effort to underutilized resources by paeans of price incentives. This will complement existing programs concerned primarily.with the acquisition of basic technical and biological data or long run improvements in harvesting efficiency as provided in part by the Fishing Fleet Improvement Act