Glutamatergic Plasticity in Medial Prefrontal Cortex and Ventral Tegmental Area Following Extended-Access Cocaine Self-Administration

Glutamate signaling in prefrontal cortex and ventral tegmental area plays an important role in the molecular and behavioral plasticity associated with addiction to drugs of abuse. The current study investigated the expression and postsynaptic density redistribution of glutamate receptors and synaptic scaffolding proteins in dorsomedial and ventromedial prefrontal cortex and ventral tegmental area after cocaine self-administration. After 14 days of extended-access (6 h/day) cocaine self-administration, rats were exposed to one of three withdrawal regimen for 10 days. Animals either stayed in home cages (Home), returned to self-administration boxes with the levers withdrawn (Box), or underwent extinction training (Extinction). Extinction training was associated with significant glutamatergic plasticity. In dorsomedial prefrontal cortex of the Extinction group, there was an increase in postsynaptic density GluR1, PSD95, and actin proteins; while postsynaptic density mGluR5 protein decreased and there was no change in NMDAR1, Homer1b/c, or PICK1 proteins. These changes were not observed in ventromedial prefrontal cortex or ventral tegmental area. In ventral tegmental area, Extinction training reversed the decreased postsynaptic density NMDAR1 protein in the Home and Box withdrawal groups. These data suggest that extinction of drug seeking is associated with selective glutamatergic plasticity in prefrontal cortex and ventral tegmental area that include modulation of receptor trafficking to postsynaptic density

Rethinking Agricultural Domestic Support under the World Trade Organization

This paper focuses on the third pillar of the Uruguay Round Agreement on Agriculture (URAA) of the World Trade Organization (WTO), the discipline of agricultural domestic support. The paper examines the current definition of agricultural domestic support used by the WTO, focusing on the Aggregate Measure of Support (AMS) and other forms of support that are less to least distorting (Blue and Green Box payments). The analysis looks at the recent experience of four member states (the United States, the European Union, Japan, and Brazil). The structure of recent support varies considerably by country. Some countries, notably the United States, have strategically used the de minimis exemption to deflate their support figures substantially in order to remain within AMS limits, even though total support has exceeded these limits. The paper investigates the possible effects of changing the definition of the AMS so that it better reflects current support conditioned by market forces. If market prices (world and/or domestic) were to be used to compute current market support, a greater variability of the AMS would result, and violations of AMS limits would be more likely given the anticyclical nature of policies included in the AMS, especially for the United States and European Union. We also identify possible changes that would lead to more substantial trade reforms. In particular, we argue for phasing out the de minimis exemption and Blue Box support, adding a generous Green Box definition, which would allow countries to move quickly away from trade-distorting policies (Amber Box and the most trade-distorting Blue Box policies), followed by a phase-down of Green Box payments over time. The recent reforms of the European Union\u27s Common Agricultural Policy (CAP) exemplify the spirit of the first part of the recommendation, while resistance to phase-down of Green Box payments may be overcome by a reasonable reduction schedule

Reallocation, Firm Turnover, and Efficiency: Selection on Productivity or Profitability?

There is considerable evidence that producer-level churning contributes substantially to aggregate (industry) productivity growth, as more productive businesses displace less productive ones. However, this research has been limited by the fact that producer-level prices are typically unobserved; thus within-industry price differences are embodied in productivity measures. If prices reflect idiosyncratic demand or market power shifts, high "productivity" businesses may not be particularly efficient, and the literature's findings might be better interpreted as evidence of entering businesses displacing less profitable, but not necessarily less productive, exiting businesses. In this paper, we investigate the nature of selection and productivity growth using data from industries where we observe producer-level quantities and prices separately. We show there are important differences between revenue and physical productivity. A key dissimilarity is that physical productivity is inversely correlated with plant-level prices while revenue productivity is positively correlated with prices. This implies that previous work linking (revenue-based) productivity to survival has confounded the separate and opposing effects of technical efficiency and demand on survival, understating the true impacts of both. We further show that young producers charge lower prices than incumbents, and as such the literature understates the productivity advantage of new producers and the contribution of entry to aggregate productivity growth.

Rethinking Agricultural Domestic Support under the World Trade Organization

The World Trade Organization (WTO) negotiations under the Doha Round are slowly progressing toward an eventual new agreement on agriculture. A new framework for the agriculture agreement was approved by the WTO membership in August 2004. The changes in the guidelines for domestic support could have effects on many countries and many types of support. However, details on the specific regulations of the agreement have yet to be determined. Dramatic reforms in agriculture could take place under the framework, but the decisions made to implement the framework will determine if that potential is realized. If countries lack ambition and commitment to make genuine reforms, changes in support will not happen in this round

The FAPRI U.S. Crops Model: Review and Suggestions

This paper provides a critical overview of the most striking problems in the 1994 version of the U.S. crops model. No model is ever perfect; however, as agricultural policies change and more data become available, the model can be improved. As we enter the 1995 Farm Bill debate, it becomes increasingly important to enhance the model structure to allow accurate analysis of the Farm Bill proposals. This review does not discuss every problem in the U.S. crops model, but does point out three areas that need to be improved for Farm Bill analysis. A critical review of a problem is not useful unless a possible solution can be presented. In addition to pointing out problems in the model this paper suggests possible solutions

The Impact of State Physical Education Requirements on Youth Physical Activity and Overweight

To combat childhood overweight, which has risen dramatically in the past three decades, many medical and public health organizations have called for students to spend more time in physical education (PE) classes. This paper is the first to exploit state PE requirements as quasi-natural experiments in order to estimate the causal impact of PE on student activity and weight. We study nationwide data from the YRBSS for 1999, 2001, and 2003 merged with data on state minimum PE requirements from the 1994 and 2000 School Health Policies and Programs Study and the 2001 Shape of the Nation Report. We find that certain state regulations are effective in raising the number of minutes during which students are active in PE. Our results also indicate that additional PE time raises the number of days per week that students report having exercised or engaged in strength-building activities, but lowers the number of days in which students report light physical activity. PE time has no detectable impact on youth BMI or the probability that a student is overweight. We conclude that while raising PE requirements may make students more active by some (but not all) measures, there is not yet the scientific base to declare raising PE requirements an anti-obesity initiative.

The Slow Growth of New Plants: Learning about Demand?

It is well known that new businesses are typically much smaller than their established industry competitors, and that this size gap closes slowly. We show that even in commodity-like product markets, these patterns do not reflect productivity gaps, but rather differences in demand-side fundamentals. We document and explore patterns in plants’ idiosyncratic demand levels by estimating a dynamic model of plant expansion in the presence of a demand accumulation process (e.g., building a customer base). We find active accumulation driven by plants’ past production decisions quantitatively dominates passive demand accumulation, and that within-firm spillovers affect demand levels but not growth.

Factors that Determine the Cost of Food

Iowa has moved to the forefront amid the shift to biorenewable sources of energy. The state is currently the leading producer of ethanol and one of the top producers in wind energy As Iowa\u27s leaders, entrepreneurs, policy makers and researchers look to accelerate development of the state\u27s biorenewable resources, other impacts emerge. Today we are making choices about our economic, environmental, and social development as well as hurdling technical issues. The recent increase in the utilization of the state\u27s biological bounty for feed, food, and fuel has affected the economic, environmental, and social dynamics of Iowa

Atypical Work: Who Gets It, and Where Does It Lead? Some U.S. Evidence Using the NLSY79

Atypical work arrangements have long been criticized as offering more precarious and lower paid work than regular open-ended employment. In an important paper, Booth et al. (2002) were among the first to recognize that notwithstanding their potential deficiencies, such jobs also functioned as a stepping stone to permanent work. This conclusion proved prescient and has received increasing support in Europe. In the present note, we provide a parallel analysis to Booth et al. for the United States – somewhat of a missing link in the evolving empirical literature – and obtain not dissimilar similar findings for the category of temporary workers as do they for fixed-term contract workers.atypical work, temporary jobs, contracting/consulting work, regular open-ended employment, earnings development