Setting Fees in Competing Double Auction Marketplaces: An Equilibrium Analysis

In this paper, we analyse competing double auction marketplaces that vie for traders and need to set appropriate fees to make a profit. Specifically, we show how competing marketplaces should set their fees by analysing the equilibrium behaviour of two competing marketplaces. In doing so, we focus on two different types of market fees: registration fees charged to traders when they enter the marketplace, and profit fees charged to traders when they make transactions. In more detail, given the market fees, we first derive equations to calculate the marketplaces' expected profits. Then we analyse the equilibrium charging behaviour of marketplaces in two different cases: where competing marketplaces can only charge the same type of fees and where competing marketplaces can charge different types of fees. This analysis provides insights which can be used to guide the charging behaviour of competing marketplaces. We also analyse whether two marketplaces can co-exist in equilibrium. We find that, when both marketplaces are limited to charging the same type of fees, traders will eventually converge to one marketplace. However, when different types of fees are allowed, traders may converge to different marketplaces (i.e. multiple marketplaces can co-exist)

Effects of semantic and syntactic complexities and aspectual class on past tense production

This paper reports results from a series of experiments that investigated whether semantic and/or syntactic complexity influences young Dutch children’s production of past tense forms. The constructions used in the three experiments were (i) simple sentences (the Simple Sentence Experiment), (ii) complex sentences with CP complements (the Complement Clause Experiment) and (iii) complex sentences with relative clauses (the Relative Clause Experiment). The stimuli involved both atelic and telic predicates. The goal of this paper is to address the following questions. Q1. Does semantic complexity regarding temporal anchoring influence the types of errors that children make in the experiments? For example, do children make certain types of errors when a past tense has to be anchored to the Utterance Time (UT), as compared to when it has to be anchored to the matrix topic time (TT)? Q2. Do different syntactic positions influence children’s performance on past-tense production? Do children perform better in the Simple Sentence Experiment compared to complex sentences involving two finite clauses (the Complement Clause Experiment and the Relative Clause Experiment)? In complex sentence trials, do children perform differently when the CPs are complements vs. when the CPs are adjunct clauses? (Lebeaux 1990, 2000) Q3. Do Dutch children make more errors with certain types of predicate (such as atelic predicates)? Alternatively, do children produce a certain type of error with a certain type of predicates (such as producing a perfect aspect with punctual predicates)? Bronckart and Sinclair (1973), for example, found that until the age of 6, French children showed a tendency to use passé composé with perfective events and simple present with imperfective events; we will investigate whether or not the equivalent of this is observed in Dutch

Echo spectroscopy and Atom Optics Billiards

We discuss a recently demonstrated type of microwave spectroscopy of trapped ultra-cold atoms known as "echo spectroscopy" [M.F. Andersen et. al., Phys. Rev. Lett., in press (2002)]. Echo spectroscopy can serve as an extremely sensitive experimental tool for investigating quantum dynamics of trapped atoms even when a large number of states are thermally populated. We show numerical results for the stability of eigenstates of an atom-optics billiard of the Bunimovich type, and discuss its behavior under different types of perturbations. Finally, we propose to use special geometrical constructions to make a dephasing free dipole trap

Making Black Bloody Rosella Jam

The rosella (or roselle) plant originated in West Africa, but has been cultivated throughout Africa, Asia and Australia. Not only can rosella be used to make teas and jams, but every part of the plant is edible; the young leaves can be eaten raw and make great salads. Rosella is a type of hibiscus, and it has a beautiful pink flower. Although the whole plant is edible, it is the calyx (the bright red fruit) that is used to make syrups, teas or jams. If you eat it fresh, straight off the stalk, it has a sour taste. Inside the calyx is a round seed pod. If it is left to mature, it will turn brown. When dry it provides the mature seeds for the next planting. At Kebun Setaman Pejeng, our small-scale community arm and learning centre at Bamjar Panglan, Pejeng, on the island of Bali, we harvest rosella to make jam

Optimal universal and categorical benefits with classification errors and imperfect enforcement

We determine the optimal combination of a universal benefit, B, and categorical benefit, C, for an economy in which individuals differ in both their ability to work – modelled as an exogenous zero quantity constraint on labour supply – and, conditional on being able to work, their productivity at work. C is targeted at those unable to work, and is conditioned in two dimensions: ex-ante an individual must be unable to work to be awarded the benefit , whilst ex-post a recipient must not subsequently work. However, the ex-ante conditionality may be imperfectly enforced due to Type I(false rejection) and Type II (false award) classification errors, whilst, in addition, the ex post conditionality may be imperfectly enforced. If there are no classification errors – and thus no enforcement issues – it is always optimal to set C>0, whilst B=0 only if the benefit budget is sufficiently small. However, when classification errors occur, B=0 only if there are no Type I errors and the benefit budget is sufficiently small, while the conditions under which C>0 depend on the enforcement of the ex-post conditionality. We consider two discrete alternatives. Under No Enforcement C>0 only if the test administering C has some discriminatory power. In addition, social welfare is decreasing in the propensity to make each type of error. However, under Full Enforcement C>0 for all levels of discriminatory power, including that of no discriminatory power. Furthermore, whilst social welfare is decreasing in the propensity to make Type I errors, there are certain conditions under which it is increasing in the propensity to make Type II errors. This implies that there may be conditions under which it would be welfare enhancing to lower the chosen eligibility threshold – supporting the suggestion by Goodin (1985) to “err on the side of kindness”.Postprin