The Local Environments of Core-Collapse SNe within Host Galaxies

We present constraints on core-collapse supernova progenitors through observations of their environments within host galaxies. This is achieved through 2 routes. Firstly, we investigate the spatial correlation of supernovae with host galaxy star formation using pixel statistics. We find that the main supernova types form a sequence of increasing association to star formation. The most logical interpretation is that this implies an increasing progenitor mass sequence going from the supernova type Ia arising from the lowest mass, through the type II, type Ib, and the supernova type Ic arising from the highest mass progenitors. We find the surprising result that the supernova type IIn show a lower association to star formation than type IIPs, implying lower mass progenitors. Secondly, we use host HII region spectroscopy to investigate differences in environment metallicity between different core-collapse types. We find that supernovae of types Ibc arise in slightly higher metallicity environments than type II events. However, this difference is not significant, implying that progenitor metallicity does not play a dominant role in deciding supernova type.Comment: to appear in Proceedings of IAU 279 "Death of Massive Stars: Supernovae and Gamma-ray Bursts

An Invertible Linearization Map for the Quartic Oscillator

The set of world lines for the non-relativistic quartic oscillator satisfying Newton's equation of motion for all space and time in 1-1 dimensions with no constraints other than the "spring" restoring force is shown to be equivalent (1-1-onto) to the corresponding set for the harmonic oscillator. This is established via an energy preserving invertible linearization map which consists of an explicit nonlinear algebraic deformation of coordinates and a nonlinear deformation of time coordinates involving a quadrature. In the context stated, the map also explicitly solves Newton's equation for the quartic oscillator for arbitrary initial data on the real line. This map is extended to all attractive potentials given by even powers of the space coordinate. It thus provides classes of new solutions to the initial value problem for all these potentials

The Impact of the National Counter-Cyclical Income Support Program for Dairy Producers on Representative Dairy Farms

This report contains the results of an analysis of the National Counter-Cyclical Income Support Program for Dairy Producers on the Agricultural and Food Policy Center’s (AFPC) representative dairy farms. The impact of the proposal on the representative farms is evaluated in terms of the change in average annual cash receipts and the change in the average annual net cash farm income. The role and potential importance of payment limits on these farms are discussed. All milk prices by state and program benefits under the payment limit binding and nonbinding scenarios were developed by FAPRI and were applied to the representative dairies. For more information on those results see the FAPRI analysis of this program.Agribusiness, Agricultural and Food Policy, Livestock Production/Industries,

Can We Save the Traditional Family Farm?

What is a traditional family farm? Is it a family of four living on a farm and supplying all of the labor, capital and management or is it a family corporation with four families supplying all of the capital and management? These types of questions continue to arise in policy debates, as they have for many years. While subject to heated debate and the core of many people’s positions on farm programs the answer is more sociological as it is becoming less and less economically relevant. Whether these types of farms or any other farm sizes should survive is not a question that can be answered by a policy analyst. The job of an analyst is to determine if and under what conditions family farms can survive. To this end, this paper reviews the various definitions of family farms and draws inferences as to the economic and financial survival of these different size farms using the results generated from simulating representative farms.Agricultural and Food Policy,

Post-Freedom to Farm Shifts in Regional Production Patterns

The FAIR Act of 1996, also known as the Freedom to Farm Act (ACT) dismantled many of the agriculture policy tools in use for the last 25 years. Gone were target prices, deficiency payments, and set asides. In their place were expanded marketing loan programs to effectively include wheat and feed grains and oilseeds in addition to cotton and rice. Full planting flexibility has been popular with farmers who are no longer constrained by base acres. Grain merchants and other volume oriented agribusinesses praise the elimination of set asides. The sharp decline in farm prices for all major program commodities since 1996 has left most farmers questioning the income safety net provisions of the FAIR Act. The flexibility and marketing loan provisions continue to be praised. Farm program changes in the 1996 farm bill rendered methods of crop supply response estimation based on econometric models, using historic data, difficult at best. Yet it can, and has been, hypothesized that the Act resulted in major shifts in regional crop production patterns. This paper draws inferences from changes in acres planted among crops for representative farms in the Texas A&M Agricultural and Food Policy Center’s (AFPC) farm data base. AFPC has maintained longitudinal data for more than three dozen representative crop farms across states, regions, farm size, and type of farm since 1990. The farms were updated in 1999 as to their crop mix changes following the ACT and the crop mix changes observed in the updates are summarized here. United States aggregate production shifts are identified from NASS data. Implications for future potential acreage changes are identified. The commodity focus includes feedgrains, soybeans, wheat, cotton, and rice.Agricultural and Food Policy,

Massively parallel support for a case-based planning system

Case-based planning (CBP), a kind of case-based reasoning, is a technique in which previously generated plans (cases) are stored in memory and can be reused to solve similar planning problems in the future. CBP can save considerable time over generative planning, in which a new plan is produced from scratch. CBP thus offers a potential (heuristic) mechanism for handling intractable problems. One drawback of CBP systems has been the need for a highly structured memory to reduce retrieval times. This approach requires significant domain engineering and complex memory indexing schemes to make these planners efficient. In contrast, our CBP system, CaPER, uses a massively parallel frame-based AI language (PARKA) and can do extremely fast retrieval of complex cases from a large, unindexed memory. The ability to do fast, frequent retrievals has many advantages: indexing is unnecessary; very large case bases can be used; memory can be probed in numerous alternate ways; and queries can be made at several levels, allowing more specific retrieval of stored plans that better fit the target problem with less adaptation. In this paper we describe CaPER's case retrieval techniques and some experimental results showing its good performance, even on large case bases

ECONOMETRIC MODEL OF THE U.S. SHEEP INDUSTRY FOR POLICY ANALYSIS

The U.S. sheep inventory has been declining for many years. To further investigate this trend, an econometric sector model using single demand equations was developed to analyze the impacts of two alternative levels of wool marketing loan rates.Marketing,

A Brief Summary of U.S. Farm Program Provisions

This brief publication began as a need for a short summary of farm programs and farm bills for two agricultural economics courses focusing on agricultural policy -- ag. economics 429, and ag. economics 614. It became clear that many students taking these courses had less and less background in agriculture and less (even cursory) knowledge of policies than those of the recent past. After this list was developed a number of other professional agricultural economists found copies and began to use it, hence its publication in a more structured form. The list of Farm Program Provisions is not all-inclusive. It certainly does not contain all the laws and provisions that have affected agriculture over the years. However, it is an easy reference to farm bills and provisions since 1933. We intend to update this list as time goes on to continue its usefulness to professionals and students alike.Agricultural and Food Policy,

Constraints on supernova progenitors from spatial correlations with H-alpha emission

We have attempted to constrain the progenitors of all supernova types, through correlations of the positions of historical supernovae with recent star formation, as traced by H-alpha emission. Through pixel statistics we have found that a large fraction of the SNII population do not show any association with current star formation, which we put down to a 'runaway' fraction of these progenitors. The SNIb/c population accurately traces the H-alpha emission, with some suggestion that the SNIc progenitors show a higher degree of correlation than the SNIb, suggesting higher mass progenitors for the former. Overall the SNIa population only show a weak correlation to the positions of HII regions, but as many as a half may be associated with a young stellar population.Comment: To appear in conference proceedings: "Supernova 1987A: 20 Years After -- Supernovae & Gamma-Ray Bursters", held in Aspen, February 200