1,293 research outputs found
ECONOMETRIC INVESTIGATION OF THE DYNAMIC EFFECTS OF THE 1983 PAYMENT-IN-KIND PROGRAM ON THE WHEAT ECONOMY
A stochastic, dynamic, and control-system econometric model of the wheat sector is developed to assess the effects of the Payment-in Kind program. Empirical results the complex dynamics of the responses. Reduced storage costs and deficiency payments for the U.S. government and increased income for wheat farmers are benefits from the PIK program in the short-run. Increased direct government transfers from the public to support the program were required. The long-run economic implications are not clearly desirable. This is due primarily to the highly sensitive international wheat market.Agricultural and Food Policy, Crop Production/Industries,
Thermal conductance as a probe of the non-local order parameter for a topological superconductor with gauge fluctuations
We investigate the effect of quantum phase slips on a helical quantum wire
coupled to a superconductor by proximity. The effective low-energy description
of the wire is that of a Majorana chain minimally coupled to a dynamical
gauge field. Hence the wire emulates a matter-coupled gauge
theory, with fermion parity playing the role of the gauged global symmetry.
Quantum phase slips lift the ground state degeneracy associated with unpaired
Majorana edge modes at the ends of the chain, a change that can be understood
as a transition between the confined and the Higgs-mechanism regimes of the
gauge theory. We identify the quantization of thermal conductance at the
transition as a robust experimental feature separating the two regimes. We
explain this result by establishing a relation between thermal conductance and
the Fredenhagen-Marcu string order-parameter for confinement in gauge theories.
Our work indicates that thermal transport could serve as a measure of non-local
order parameters for emergent or simulated topological quantum order.Comment: 5 pages, 2 figures; v2: different introduction, added references,
updated figure 2; published version to appear in PR
Nilpotent Networks and 4D RG Flows
Starting from a general SCFT, we study the network of
SCFTs obtained from relevant deformations by nilpotent mass
parameters. We also study the case of flipper field deformations where the mass
parameters are promoted to a chiral superfield, with nilpotent vev. Nilpotent
elements of semi-simple algebras admit a partial ordering connected by a
corresponding directed graph. We find strong evidence that the resulting fixed
points are connected by a similar network of 4D RG flows. To illustrate these
general concepts, we also present a full list of nilpotent deformations in the
case of explicit SCFTs, including the case of a single
D3-brane probing a - or -type F-theory 7-brane, and 6D conformal
matter compactified on a , as described by a single M5-brane probing a
- or -type singularity. We also observe a number of numerical
coincidences of independent interest, including a collection of theories with
rational values for their conformal anomalies, as well as a surprisingly nearly
constant value for the ratio for the entire
network of flows associated with a given UV SCFT. The
submission also includes the full dataset of theories which
can be accessed with a companion script.Comment: v2: 73 pages, 12 figures, clarifications and references adde
From Majorana Fermions to Topological Order
We consider a system consisting of a 2D network of links between Majorana
fermions on superconducting islands. We show that the fermionic Hamiltonian
modeling this system is topologically-ordered in a region of parameter space.
In particular we show that Kitaev's toric code emerges in fourth-order
perturbation theory. By using a Jordan-Wigner transformation we can map the
model onto a family of signed 2D Ising models in a transverse field where the
signs (FM or AFM) are determined by additional gauge bits. Our mapping allows
an understanding of the non-perturbative regime and the phase transition to a
non-topological phase. We discuss the physics behind a possible implementation
of this model and argue how it can be used for topological quantum computation
by adiabatic changes in the Hamiltonian.Comment: 4+4 pages, 5 figures. v2 has a new reference and a few new comments.
In v3: yet another new reference and Supplementary Material is renamed
Appendix. In v4: several typos are corrected, to appear in Phys. Rev. Let
A Forecasting-Programming Method for Swine Production-Marketing Decisions
This study reports on the development and progress of a forecasting-programming model for swine inventory management and marketing decisions. This model considers interrelationships between breeding herd, feeder pig and finishing hog activities. Objectives were: 1. To structure a dynamic operational decision model for a modern farrow-to-finish swine confinement unit which conforms with economic theory, uses price and cost forecast information and is as consistent as possible with current production scheduling practices. 2. To use and test this model during a combined production and marketing decision process and to compare economic results with results of a standard strategy
A Forecasting-Programming Method for Swine Production-Marketing Decisions
This study reports on the development and progress of a forecasting-programming model for swine inventory management and marketing decisions. This model considers interrelationships between breeding herd, feeder pig and finishing hog activities. Objectives were: 1. To structure a dynamic operational decision model for a modern farrow-to-finish swine confinement unit which conforms with economic theory, uses price and cost forecast information and is as consistent as possible with current production scheduling practices. 2. To use and test this model during a combined production and marketing decision process and to compare economic results with results of a standard strategy
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Pedagogic change by Zambian primary school teachers participating in the OER4Schools professional development programme for one year
Supporting and upskilling teachers are essential to enhancing the quality of learning in developing contexts – the focus of Education For All – yet little evidence exists concerning what kinds of teacher education are actually most effective and what changes in ‘quality’ are desired and feasible. This paper illustrates how a concrete, research-informed school-based, model of professional development in sub-Saharan Africa can address the quality agenda. It reports on a trial of a pioneering, multimedia programme supporting interactive mathematics and science teaching using open educational resources and classroom digital technology, where available. The programme was carefully adapted to the Zambian context and ran weekly for one school year with 12 teachers in a low-resourced primary school. The study examined the impact on teachers' thinking and classroom practices. Data were derived from observations, lesson and workshop recordings, teacher interviews, portfolios and audio diaries. Through a teacher-led workshop approach and trialling new pedagogical strategies, teachers raised their expectations of pupils, adapted to learners’ knowledge levels, used more practical and group work, and integrated technology use. Pupils built deeper understanding of subject matter, were actively engaged, worked collaboratively and used digital technologies for problem-solving.Commonwealth Education Trus
Orderly Production and Marketing in the Beef-Pork Sector
This study will present economic models for analyzing temporal equilibrium positions for the beef-pork sector. The issues of spatial distribution, storage, and meat forms will not be directly analyzed. Grade and yield changes for various carcass classes will, however, be implied in the carrying costs of the animal. The models will be designed such that a number of different factors that affect the production and marketing of beef and pork can be analyzed simultaneously
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