Wetland restoration within agricultural watersheds: Balancing water quality protection with habitat conservation

Peat wetlands that have been restored from agricultural Land have the potential to act as Long term sources of phosphorus (P) and, therefore have to potenital to accelerate freshwater eutrophication. During a two-year study the water table in a eutrophic fen peat that was managed by pump drainage fluctuated annually between +20 cm and -60 cm relative to ground Level. This precise management was facilitated by the high hydraulic conductivity (K) of the humified peat (1.1 x 10(-5) m s(-1)) below around 60 cm depth. However, during one week of intermittent pumping, as much as 50 g ha(-1) dissolved P entered the pumped ditch. Summer. rainfall events and autumn reflooding also triggered P losses. The P Losses were attributed to the low P sorption capacity (217 mg kg(-1)) of the saturated peat below 60 cm, combined with its high K and the reductive dissolution of Fe bound P.

Determinants of intention to purchase chicken in Italy: the role of consumer risk perception and trust in different information sources

The article investigates how purchasing intentions among a sample of Italian consumers are influenced by different levels of risk perception and their trust in food-safety information provided by different sources such as the food industry, government agencies, or consumers' associations. The assessment of the determinants of intention to purchase was carried out by estimating a causal model for the chicken case in which attitudes, subjective norms, and perceived risk play a major role in determining buyer's behavior. In particular, the role of trust in influencing risk perception is highlighted either as a general construct or as specific constructs targeting food chain, policy actors, and the media. [EconLit citations: Q130, Q190, D120]. (C) 2008 Wiley Periodicals, Inc.

Differential recognition of Staphylococcus aureus quorum-sensing signals depends on both extracellular loops 1 and 2 of the transmembrane sensor AgrC.

Virulence in Staphylococcus aureus is regulated via agr-dependent quorum sensing in which an autoinducing peptide (AIP) activates AgrC, a histidine protein kinase. AIPs are usually thiolactones containing seven to nine amino acid residues in which the thiol of the central cysteine is linked to the alpha-carboxyl of the C-terminal amino acid residue. The staphylococcal agr locus has diverged such that the AIPs of the four different S. aureus agr groups self-activate but cross-inhibit. Consequently, although the agr system is conserved among the staphylococci, it has undergone significant evolutionary divergence whereby to retain functionality, any changes in the AIP-encoding gene (agrD) that modifies AIP structure must be accompanied by corresponding changes in the AgrC receptor. Since AIP-1 and AIP-4 only differ by a single amino acid, we compared the transmembrane topology of AgrC1 and AgrC4 to identify amino acid residues involved in AIP recognition. As only two of the three predicted extracellular loops exhibited amino acid differences, site-specific mutagenesis was used to exchange the key AgrC1 and AgrC4 amino acid residues in each loop either singly or in combination. A novel lux-based agrP3 reporter gene fusion was constructed to evaluate the response of the mutated AgrC receptors. The data obtained revealed that while differential recognition of AIP-1 and AIP-4 depends primarily on three amino acid residues in loop 2, loop 1 is essential for receptor activation by the cognate AIP. Furthermore, a single mutation in the AgrC1 loop 2 resulted in conversion of (Ala5)AIP-1 from a potent antagonist to an activator, essentially resulting in the forced evolution of a new AIP group. Taken together, our data indicate that loop 2 constitutes the predicted hydrophobic pocket that binds the AIP thiolactone ring while the exocyclic amino acid tail interacts with loop 1 to facilitate receptor activation.

The impact of price promotions on producer strategies in markets with large product heterogeneity

Although current research indicates that increasing the number of options has negative effects on the cognitive ability of consumers, little understanding has been given to the consequences on producers and their strategic behavior. This article tests whether a large portfolio of products is beneficial to producers by observing UK consumer response to price promotions. The article shows that discounts induce mainly segment switching (74% of the total impact), with a limited effect on stockpiling (26%) and no impact on purchase incidence. Consequently, consumers prefer to “follow the discount” rather than purchase multiple units of the same wine. This result seems to explain the current structure of the market, and suggests that discounts may conflict with segment loyalty, a situation that disfavors producers, particularly in very populated segments. Results also casts doubts on the economic sustainability of competition based on an intense product differentiation in the wine sector.

When do export subsidies have a redistributional role? Reply

Our differences are three. The first arises from the belief that "... a nonzero value for the optimally chosen policy instrument implies that the instrument is efficient for redistribution" (Alston, Smith, and Vercammen, p. 543, paragraph 3). Consider the two equations: (1) o* = f(P3) and (2) = -f(3) ++r h* (a, P3) representing the solution to the problem of maximizing weighted, Marshallian surplus using, simultaneously, a per-unit border intervention, 9, and a per-unit domestic intervention, wr. In the solution, parameter ot denotes the weight applied to producer surplus; parameter p denotes the weight applied to government revenues; consumer surplus is implicitly weighted one; and the country in question is small in the sense that it is unable to affect world price by any of its domestic adjustments (see the Appendix). Details of the forms of the functions f((P) and h(ot, p) are easily derived, but what matters in the context of Alston, Smith, and Vercammen's Comment is: Redistributivep referencest hatf avorp roducers are consistent with higher values "alpha," and whereas the optimal domestic intervention, 7r*, has both "alpha and beta effects," the optimal border intervention, r*, has only a "beta effect,"-it does not have a redistributional role. Garth Holloway is reader in agricultural economics and statistics, Department of Agricultural and Food Economics, School of Agriculture, Policy, and Development, University of Reading. The author is very grateful to Xavier Irz, Bhavani Shankar, Chittur Srinivasan, Colin Thirtle, and Richard Tiffin for their comments and their wisdom; and to Mario Mazzochi, Marinos Tsigas, and Cal Turvey for their scholarship, including help in tracking down a fairly complete collection of the papers that cite Alston and Hurd. They are not responsible for any errors or omissions. Note, in equation (1), that the border intervention is positive whenever a distortion exists because 8 > 0 implies 3 - 1 + 8 > 1 and, thus, f((P) > 0 (see Appendix). Using Alston, Smith, and Vercammen's definition, the instrument is now "efficient," and therefore has a redistributive role. But now, suppose that the distortion is removed so that 3 - 1 + 8 = 1, 8 = 0, and consequently the border intervention is zero. According to Alston, Smith, and Vercammen, the instrument is now "inefficient" and has no redistributive role. The reader will note that this thought experiment has said nothing about supporting farm incomes, and so has nothing whatsoever to do with efficient redistribution. Of course, the definition is false. It follows that a domestic distortion arising from the "excess-burden argument" 3 = 1 + 8, 8 > 0 does not make an export subsidy "efficient." The export subsidy, having only a "beta effect," does not have a redistributional role. The second disagreement emerges from the comment that Holloway "... uses an idiosyncratic definition of the relevant objective function of the government (Alston, Smith, and Vercammen, p. 543, paragraph 2)." The objective function that generates equations (1) and (2) (see the Appendix) is the same as the objective function used by Gardner (1995) when he first questioned Alston, Carter, and Smith's claim that a "domestic distortion can make a border intervention efficient in transferring surplus from consumers and taxpayers to farmers." The objective function used by Gardner (1995) is the same objective function used in the contributions that precede it and thus defines the literature on the debate about borderversus- domestic intervention (Streeten; Yeh; Paarlberg 1984, 1985; Orden; Gardner 1985). The objective function in the latter literature is the same as the one implied in another literature that originates from Wallace and includes most notably Gardner (1983), but also Alston and Hurd. Amer. J. Agr. Econ. 86(2) (May 2004): 549-552 Copyright 2004 American Agricultural Economics Association This content downloaded on Tue, 15 Jan 2013 07:58:41 AM All use subject to JSTOR Terms and Conditions 550 May 2004 Amer. J. Agr. Econ. The objective function in Holloway is this same objective function-it is, of course, Marshallian surplus.1 The third disagreement concerns scholarship. The Comment does not seem to be cognizant of several important papers, especially Bhagwati and Ramaswami, and Bhagwati, both of which precede Corden (1974, 1997); but also Lipsey and Lancaster, and Moschini and Sckokai; one important aspect of Alston and Hurd; and one extremely important result in Holloway. This oversight has some unfortunate repercussions. First, it misdirects to the wrong origins of intellectual property. Second, it misleads about the appropriateness of some welfare calculations. Third, it prevents Alston, Smith, and Vercammen from linking a finding in Holloway (pp. 242-43) with an old theorem (Lipsey and Lancaster) that settles the controversy (Alston, Carter, and Smith 1993, 1995; Gardner 1995; and, presently, Alston, Smith, and Vercammen) about the efficiency of border intervention in the presence of domestic distortions.

Targeting Staphylococcus aureus quorum sensing with non-peptidic small molecule inhibitors

A series of 3-oxo-C12-HSL, tetramic acid and tetronic acid analogues was synthesized to gain insights into the structural requirements for quorum sensing inhibition in Staphylococcus aureus. Compounds active against agr were non-competitive inhibitors of the auto-inducing peptide (AIP)-activated AgrC receptor, by altering the activation efficacy of the cognate AIP-1. They appeared to act as negative allosteric modulators and are exemplified by 3-tetradecanoyltetronic acid 17 which reduced nasal cell colonization and arthritis in a murine infection model.