Pohlmeyer reduction revisited

A systematic group theoretical formulation of the Pohlmeyer reduction is presented. It provides a map between the equations of motion of sigma models with target-space a symmetric space M=F/G and a class of integrable multi-component generalizations of the sine-Gordon equation. When M is of definite signature their solutions describe classical bosonic string configurations on the curved space-time R_t\times M. In contrast, if M is of indefinite signature the solutions to those equations can describe bosonic string configurations on R_t\times M, M\times S^1_\vartheta or simply M. The conditions required to enable the Lagrangian formulation of the resulting equations in terms of gauged WZW actions with a potential term are clarified, and it is shown that the corresponding Lagrangian action is not unique in general. The Pohlmeyer reductions of sigma models on CP^n and AdS_n are discussed as particular examples of symmetric spaces of definite and indefinite signature, respectively.Comment: 45 pages, LaTeX, more references added, accepted for publication in JHE

Getting real about food prices

The 2008 price spike in world grain prices had serious impacts on food security and poverty but analysts have consistently described these real food prices as low in historical terms. The inconsistency between the severity of the food crisis and low real prices results from the use of advanced and global economy price indices to calculate real prices. This ignores the high share of food in poor people’s expenditures and indirect effects of income growth on expenditure patterns of rich and poor consumers. Poor consumers have not experienced the same falls in real food prices as those with growing incomes and are more vulnerable to price shocks. As high and fluctuating international grain prices appear to be a feature of the current world economy, food price and policy analysis must recognise this, and develop and use different price indices that take account of differences between consumer groups

Generalized stochastic Schroedinger equations for state vector collapse

A number of authors have proposed stochastic versions of the Schr\"odinger equation, either as effective evolution equations for open quantum systems or as alternative theories with an intrinsic collapse mechanism. We discuss here two directions for generalization of these equations. First, we study a general class of norm preserving stochastic evolution equations, and show that even after making several specializations, there is an infinity of possible stochastic Schr\"odinger equations for which state vector collapse is provable. Second, we explore the problem of formulating a relativistic stochastic Schr\"odinger equation, using a manifestly covariant equation for a quantum field system based on the interaction picture of Tomonaga and Schwinger. The stochastic noise term in this equation can couple to any local scalar density that commutes with the interaction energy density, and leads to collapse onto spatially localized eigenstates. However, as found in a similar model by Pearle, the equation predicts an infinite rate of energy nonconservation proportional to $\delta^3(\vec 0)$, arising from the local double commutator in the drift term.Comment: 24 pages Plain TeX. Minor changes, some new references. To appear in Journal of Physics

Consuming post-disaster destinations: The case of Sichuan, China

Addressing the call for a better understanding of tourist behavior in relation to post-disaster destinations, this study explores the motivations and intentions of potential domestic tourists (from non-hit areas) to visit Sichuan, China in the aftermath of an earthquake. Drawing on dark tourism theories, this study offers a more comprehensive insight into the consumption of post-disaster destinations, aiming to capture the impact of the changes to the destination’s attributes on tourist behavior. The findings move beyond the common approach to tourism recovery, which solely focuses on reviving the traditional ‘‘non-dark’’ products. This study reveals the importance of newly formed dark attributes that emerge from the disaster as another means to destination recovery, reflected in the emergence of new tourist segments

Compliance Calendar/Logbook for Bulk Gasoline Plants: Less than 19,999 Gallons/Day Throughput

EPA has new requirements for Gasoline Distribution Bulk Terminals, Bulk Gasoline Plants and Pipeline Facilities under 40 CFR Part 63 Subpart BBBBBB (NESHAP 6B) to reduce air pollution. This calendar has been developed to assist Bulk Gasoline Plants in complying with NESHAP 6B. Additional Iowa specific NESHAP 6B rules are discussed later.https://scholarworks.uni.edu/iwrc_facbook/1004/thumbnail.jp

Golf Course Pollution Prevention Guide

According to the Environmental Protection Agency (EPA), pollution prevention can be defined as: “The use of materials, processes, or practices that reduces or eliminates the creation of pollutants or wastes at the source.” Pollution prevention represents a shift away from the old school of thought, “pollution control,” in which waste was not dealt with until after it was generated. Through pollution prevention, we look at the processes that generate the waste to see if we can avoid creating a waste in the first place, or at least reduce the hazardous nature of the waste. When this is not possible, the next best solution to prevent wastes from having a negative impact on the environment is through careful management and recycling. This manual will help golf course maintenance staff identify areas where pollution prevention techniques can be applied in a practical manner. Each section presents a waste type common to golf courses accompanied by pollution prevention recommendations. Although the focus of this manual is on pollution prevention, regulatory information is given as necessary where it impacts pollution prevention practices and to illustrate how pollution prevention can help reduce regulatory requirements.https://scholarworks.uni.edu/iwrc_facbook/1008/thumbnail.jp