Radiation scales and the solar constant

Radiation measurement and solar constant determinatio

Agricultural and resource economics and economic development in Aboriginal communities

Economic development is seen as the best way for Aboriginal communities to improve their welfare and lessen the considerable disadvantages they suffer. Unfortunately, the economics profession has shown little interest in their plight. Agricultural and resource economists have much to offer in helping to foster economic development in Aboriginal communities throughout Australia. Suggestions are made as to various ways in which our particular interests and experiences can hopefully be applied.International Development, Resource /Energy Economics and Policy,

World food markets into the 21st century: commodity risk management policies

Recent concerns about future global food production seem poorly based. The rapid phase of growth in food consumption is over for most of the world's population because of increased incomes and, besides, population growth rates continue to slow. Thus, the rate of growth of food production needed in the future is much lower than it has been for the past 40 years. Production and price instability will continue, perhaps with lessened intensity because of reduced government intervention. With private agricultural interests now facing greater exposure to price and production risks, especially in developing countries, there needs to be greater emphasis on financial market instruments for managing these risks.International Relations/Trade,

String Breaking in Four Dimensional Lattice QCD

Virtual quark pair screening leads to breaking of the string between fundamental representation quarks in QCD. For unquenched four dimensional lattice QCD, this (so far elusive) phenomenon is studied using the recently developed truncated determinant algorithm (TDA). The dynamical configurations were generated on an Athlon 650 MHz PC. Quark eigenmodes up to 420 MeV are included exactly in these TDA studies performed at low quark mass on large coarse (but O($a^2$) improved) lattices. A study of Wilson line correlators in Coulomb gauge extracted from an ensemble of 1000 two-flavor dynamical configurations reveals evidence for flattening of the string tension at distances R $\geq$ approximately 1 fm.Comment: 16 pages, 5 figures, Latex (deleted extraneous eps figure file

Demographic and psychological variables affecting test subject evaluations of ride quality

Ride-quality experiments similar in objectives, design, and procedure were conducted, one using the U.S. Air Force Total In-Flight Simulator and the other using the Langley Passenger Ride Quality Apparatus to provide the motion environments. Large samples (80 or more per experiment) of test subjects were recruited from the Tidewater Virginia area and asked to rate the comfort (on a 7-point scale) of random aircraft motion typical of that encountered during STOL flights. Test subject characteristics of age, sex, and previous flying history (number of previous airplane flights) were studied in a two by three by three factorial design. Correlations were computed between one dependent measure, the subject's mean comfort rating, and various demographic characteristics, attitudinal variables, and the scores on Spielberger's State-Trait Anxiety Inventory. An effect of sex was found in one of the studies. Males made higher (more uncomfortable) ratings of the ride than females. Age and number of previous flights were not significantly related to comfort ratings. No significant interactions between the variables of age, sex, or previous number of flights were observed

Shortcuts to Adiabaticity Assisted by Counterdiabatic Born-Oppenheimer Dynamics

Shortcuts to adiabaticity (STA) provide control protocols to guide the dynamics of a quantum system through an adiabatic reference trajectory in an arbitrary prescheduled time. Designing STA proves challenging in complex quantum systems when the dynamics of the degrees of freedom span different time scales. We introduce Counterdiabatic Born-Oppenheimer Dynamics (CBOD) as a framework to design STA in systems with a large separation of energy scales. CBOD exploits the Born-Oppenheimer approximation to separate the Hamiltonian into effective fast and slow degrees of freedom and calculate the corresponding counterdiabatic drivings for each subsystem. We show the validity of the CBOD technique via an example of coupled harmonic oscillators, which can be solved exactly for comparison, and further apply it to a system of two-charged particles.Comment: 14 pages, 3 figures, published New Journal of Physic

GMC Collisions As Triggers of Star Formation. IV. The Role of Ambipolar Diffusion

We investigate the role of ambipolar diffusion (AD) in collisions between magnetized giant molecular clouds (GMCs), which may be an important mechanism for triggering star cluster formation. Three dimensional simulations of GMC collisions are performed using a version of the Enzo magnetohydrodynamics code that has been extended to include AD. The resistivities are calculated using the 31-species chemical model of Wu et al. (2015). We find that in the weak-field, $10\:{\rm \mu G}$ case, AD has only a modest effect on the dynamical evolution during the collision. However, for the stronger-field, $30\:{\rm \mu G}$ case involving near-critical clouds, AD results in formation of dense cores in regions where collapse is otherwise inhibited. The overall efficiency of formation of cores with $n_{\rm H}\geq10^{6}\:{\rm cm}^{-3}$ in these simulations is increases from about 0.2% to 2% once AD is included, comparable to observed values in star-forming GMCs. The gas around these cores typically has relatively slow infall at speeds that are a modest fraction of the free-fall speed.Comment: 15 pages, 15 figures, Accepted to Ap

A survey of the costs of world sugar policies

This paper provides a framework for assessing the prospects for trade reform in the sugar market. It begins by explaining the main features of the policy formation processes affecting the sugar market. The discussion draws heavily on a recent model of the world market developed by Wong, Sturgiss and Borrell (1989), and some parts of this paper summarize that work directly. Some of the key features of existing policies are discussed and the findings of a number of empiricalstudies are highlighted to draw attention to the economic costs and welfare effects of such policies. The paper concludes with an assessment of the prospects for reform.Access to Markets,Economic Theory&Research,Agribusiness&Markets,Environmental Economics&Policies,Markets and Market Access