Waste, Recycling, and "Design for Environment": Roles for Markets and Policy Instruments

Several studies that have solved for optimal solid waste policy instruments have suggested that transaction costs may often prevent the working of recycling markets. In this paper, we explicitly incorporate such costs into a general equilibrium model of production, consumption, recycling, and disposal. Specifically, we assume that consumers have access to both recycling without payment and recycling with payment but that the latter option comes with transaction costs. Producers choose material and nonmaterial inputs to produce a consumer product, and they also choose design attributes of that product—its weight and degree of recyclability. We find that the policy instruments that yield a social optimum in this setting need to vary with the degree of recyclability of products. Moreover, they need to be set to ensure that recycling markets do not operate—that is, that all recycling takes place without an exchange of money between recyclers and consumers. We argue that implementing such a policy would be difficult in practice. We then solve for a simpler set of instruments that implement a constrained (second-best) optimum. We find the results in this setting more encouraging: a modest disposal fee—less than the Pigouvian fee—combined with a common deposit-refund applied to all products will yield the constrained optimum. Moreover, this set of constrained optimal instruments is robust to the possibility that consumers imperfectly sort used products into trash and recyclables.Dfe, deposit-refund, disposal fee, constrained optimum

Competition between highway operators: can we expect toll differentiation?

Where there are alternative roads to the same destination, competition between profit maximizing road operators is possible. Tolls on such roads could perform two welfare enhancing functions; discouraging excessive driving and allocating drivers between roads. The second of these functions will typically require some roads to be more expensive to drive on, and to be less congested, than others. Bertrand equilibrium will not always peform this second function. It may fail to allocate the most impatient drivers to less congested roads, as it does not always deliver toll differentiation. The performance of this second function is dependent on the first. That is, whether or not competing roads will be differentiated by tolls and congestion, will depend in part on the importance of discouraging marginal drivers. The equilibrium will not generally be fully efficient, but will often provide efficiency gains over other decentralized options.congestion, road pricing, networks, market structure

Policies to Encourage Recycling and "Design for Environment": What to Do When Markets are Missing

Several studies have shown the efficiency of both a Pigovian tax on waste disposal and a deposit-refund instrument, that is a combined output tax and recycling subsidy. The efficiency of these instruments, however, critically depends on households being paid for recycling. In reality, although most households have access to curbside recycling services, they are not paid for the items they set out at the curb. All items placed in a recycling bin are thus of equal value to a household, and there is no incentive for producers to make their products any more recyclable than what is necessary to be eligible for the bin. This paper characterizes the constrained (second-best) optimum that exists with the missing recycling market and solves for a modified deposit-refund instrument that will achieve the constrained optimum.

A Roomful of Robovacs: How to Think About Genetic Programs

The notion of a genetic program has been widely criticized by both biologists and philosophers. But the debate has revolved around a narrow conception of what programs are and how they work, and many criticisms are linked to this same conception. To remedy this, I outline a modern and more apt idea of a program that possesses many of the features critics thought missing from programs. Moving away from over-simplistic conceptions of programs opens the way to a more fruitful interplay of ideas between the complexity of biology and our most complex engineering discipline

Transient Loss of Plasmid Mediated Mercuric Ion Resistance After Freezing and Thawing of Pseudomonas Auerginosa

Author Institution: Department of Biological Sciences, Wright State UniversityAfter freezing and thawing, Pseudomonas aeruginosa harboring a drug resistance plasmid (Hg , Strep ), became acutely sensitive to mercuric ions but not to streptomycin in the plating medium. Its sensitivity to both agents in the plating medium became more pronounced, suggesting a synergistic effect of the mercuric ions with streptomycin. This freeze-thaw-induced sensitivity was transient and capable of being repaired in a simple salts medium (0.5%K2HPO4 + 0.04%MJSO4 pH7.7). Transient wall and membrane damage were also observed in frozen-thawed preparations. From kinetics studies, repair of membrane damage preceded repair of wall damage and damage measured by mercuric ions and mercuric ions plus streptomycin. Osmotically shocked cells also were sensitive to mercuric ions, mercuric ions plus streptomycin and sodium lauryl sulfate, but not to sodium chloride or streptomycin alone. This sensitivity was transient and capable of repair in the same simple salts medium. Active transport of a non-metabolisable amino acid, a-amino isobutyric acid, was sensitive to mercuric ions and became more so after freezing and thawing. A freeze-thaw resistant mercuric ion dependent NADPH oxido-reductase was localized in the cytoplasm, and the enzyme and an intact outer membrane appear to be required for mercuric ion resistance in this strain

Further Clarification on Permissive and Instructive Causes

I respond to recent criticism of my analysis of the permissive-instructive distinction and outline problems with the alternative analysis on offer. Amongst other problems, I argue that the use of formal measures is unclear and unmotivated, that the distinction is conflated with others that are not equivalent, and that no good reasons are provided for thinking the alternative model or formal measure tracks what biologists are interested in. I also clarify my own analysis where it has been misunderstood or ignored

Xenophobia in the ‘Rainbow Nation’: An Analysis of Intergroup Conflict in Contemporary South Africa

Since the inception of democracy in South Africa, the nation has been touted as an example of racial reconciliation and harmonious diversity. However, the xenophobic violence that has plagued the state since 2008 and resulted in hundreds of fatalities reveals deep and ongoing intergroup divides. Dehumanizing rhetoric around immigration is propagated by both elected officials and the media, and non-natives are frequently characterized as ‘parasitic’ and ‘criminal.’ In this paper I suggest that the xenophobic violence observed in contemporary South Africa may be explained via a three-pronged analysis: the construction of an ‘exceptional’ South African social identity during the early years of democratic rule, the intergroup conflict instigated by job scarcity, and the mythologized scapegoating of migrant workers as an outgroup responsible for the lack of opportunity that persists despite majority rule

Can we test for supplier-induced demand by comparing informed with uninformed consumers?

Two tests for supplier induced demand are evaluated. Both tests are based on the greater vulnerability to demand inducement of less informed consumers. The first test is whether less informed consumers have higher utilisation of a procedure than more informed consumers. The second is whether they have higher utilisation, given that they have sought medical advice. Both tests are shown to be flawed. The absence of demand inducement is compatible with positive results of either test and the presence of demand inducement is compatible with negative results of both tests

Engineering the biosynthesis of non-ribosomal peptides

Non-ribosomal peptides are a class of natural product that exhibit diverse properties and function as toxins, antibiotics, siderophores, and pigments. Their range of activity means they have roles in medicine, agriculture and bioremediation. Non-ribosomal peptides are biosynthesised by linking monomers together via peptide bonds. They are assembled from a pool of hundreds of monomers, and often contain cyclisation or other modifications not found in ribosomally-synthesised peptides. Their structural diversity means they can be expensive and/or difficult to synthesise. Consequently, many non-ribosomal peptides are produced using fermentation and then modified to generate compounds suitable for medical or industrial applications. Modifying the biosynthetic pathways could provide a cheap and scalable source of new compounds but attempts to engineer them have previously had a low success rate. Using pyoverdine as a model system, this study investigated how to rationally engineer non-ribosomal peptide biosynthesis and generated modified pyoverdines in 6/9 cases. The results of modifying pyoverdine were then used to engineer a second pathway to make dipeptides with a 3/5 success rate. The high success rate and similar results using two biosynthetic pathways suggest this approach is highly transferable and will be valuable for engineering other pathways