Convergence in a multidimensional randomized Keynesian beauty contest

We study the asymptotics of a Markovian system of $N \geq 3$ particles in $[0,1]^d$ in which, at each step in discrete time, the particle farthest from the current centre of mass is removed and replaced by an independent $U [0,1]^d$ random particle. We show that the limiting configuration contains $N-1$ coincident particles at a random location $\xi_N \in [0,1]^d$. A key tool in the analysis is a Lyapunov function based on the squared radius of gyration (sum of squared distances) of the points. For d=1 we give additional results on the distribution of the limit $\xi_N$, showing, among other things, that it gives positive probability to any nonempty interval subset of $[0,1]$, and giving a reasonably explicit description in the smallest nontrivial case, N=3.Comment: 26 pages, 4 figure

Maternal Expression Relaxes Constraint on Innovation of the Anterior Determinant, bicoid

The origin of evolutionary novelty is believed to involve both positive selection and relaxed developmental constraint. In flies, the redesign of anterior patterning during embryogenesis is a major developmental innovation and the rapidly evolving Hox gene, bicoid (bcd), plays a critical role. We report evidence for relaxation of selective constraint acting on bicoid as a result of its maternal pattern of gene expression. Evolutionary theory predicts 2-fold greater sequence diversity for maternal effect genes than for zygotically expressed genes, because natural selection is only half as effective acting on autosomal genes expressed in one sex as it is on genes expressed in both sexes. We sample an individual from ten populations of Drosophila melanogaster and nine populations of D. simulans for polymorphism in the tandem gene duplicates bcd, which is maternally expressed, and zerknüllt (zen), which is zygotically expressed. In both species, we find the ratio of bcd to zen nucleotide diversity to be two or more in the coding regions but one in the noncoding regions, providing the first quantitative support for the theoretical prediction of relaxed selective constraint on maternal-effect genes resulting from sex-limited expression. Our results suggest that the accelerated rate of evolution observed for bcd is owing, at least partly, to variation generated by relaxed selective constraint

Minimizing Sonic Boom Through Simulation-Based Design: The X-59 Airplane

One of NASAs six Strategic Thrusts for aeronautics is Innovation in Commercial Supersonic Aircraft, with a vision of fast air travel widely available to the traveling public. Future supersonic aircraft will be efficient, affordable, and environmentally responsible, generating an acceptable level of en-route noise (sonic booms). The first major step is the ongoing construction of the new X-59 Quiet SuperSonic Technology X-plane to demonstrate technologies that reduce sonic booms to gentle thumps. By using highresolution Cart3D computational fluid dynamics simulations, the shape of the aircraft can be designed to control the non-linear interactions of shock waves to reduce the sonic boom noise on the ground to within outdoor ambient levels, thereby enabling supersonic overland flight

sBOOM Propagation for the Third AIAA Sonic Boom Prediction Workshop

No abstract availabl

Exploring the Role of Information Systems Resources in Dynamic Environments

This study seeks to understand the role of information systems (IS) resources in dynamic environments. To date, 30 interviews have been conducted with senior managers in charge of online retail commerce operations. The results appear to challenge the research literature both in terms of the composition of IS resources and the role that they play in sustained competitiveness. This paper describes preliminary results from the first phase of a multi-phase study on how IS resources affect the firm

Spending flexibility and safe withdrawal rates

Shortfall risk retirement income analyses offer little insight into how much risk is optimal, and how risk tolerance affects retirement income decisions. This study models retirement income risk in a manner consistent with risk tolerance in portfolio selection in order to estimate optimal asset allocations and withdrawal rates for retirees with different risk attitudes. We find that the 4 percent retirement withdrawal rate strategy may only be appropriate for risk averse clients with moderate guaranteed income sources. The ability to accept greater shortfall probabilities means that risk tolerant investors will prefer a higher withdrawal rate and a riskier retirement portfolio. A risk tolerant client may prefer a withdrawal rate of between 5 and 7 percent with a guaranteed income of $20,000. The optimal retirement portfolio allocation to stock increases by between 10 and 30 percentage points and the optimal withdrawal rate increases by between 1 and 2 percentage points for clients with a guaranteed income of$60,000 instead of $20,000.retirement planning; utility maximization; retirement spending goals; safe withdrawal rates

Semileptonic decays of heavy mesons and the standard model

The formalism for a helicity amplitude analysis of the exclusive semileptonic decays of B mesons (B → Dlv and B → D* lv for l = e, µ and r) is introduced. In particular it is shown how measurements of the angular distribution of the subsequent decay D* → Dπ can fully determine the theoretically uncertain hadronic (B → D,D*) matrix elements. A spectator quark based model for the hadronic amplitudes is introduced, and then compared to other existing models and with the presently available experimental data, to extract the quark mixing matrix element |V(_eb)|. The extraction of |V(_ub)|, using exclusive models for b → u decays, is also discussed. The predictions of the free-quark model of inclusive semileptonic B decays are compared with those of the exclusive models, in an attempt to test the reliability of the inclusive model's predictions for |V(_eb)| and |V(_ub)|. A phenomenological analysis of experimental measurements of K(^0) – K(^0) and B(^0) – B(0) mixing is made, incorporating the above determinations of the mixing matrix elements, with a view to constraining the parameters of the standard model, such as the mass of the top-quark

Zinc nutrition of three corn cultivars (Zea mays L.) as affected by environment and zinc rates

Three varieties of corn (Zea mays L.) were grown under two different environmental conditions for 21 days in a growth chamber. The soil used was a Zn deficient Bradyville silt loam which was treated with five rates of Zn fertilizer. Available soil Zn was determined by four different extracting solutions. The concentration of Zn in the plants, and the available soil Zn, were not changed between the cool and warm environment. However, the warmer environment decreased the number of Zn deficient plants. Phosphorus concentration in the tissue, as well as measured soil P, were lower in the warm condition. This decrease in P may partially alleviate the Zn-P imbalance and result in the reduced number of deficient plants. The Zn concentration and uptake and the P concentration and uptake were similar in all three varieties, yet they varied greatly in development of visual deficiency symptoms. The applied Zn rates increased Zn concentration in the plants, and available soil Zn. All four soil tests correlated well with plant Zn concentrations, but rather poorly with deficiency symptoms. Soil test correlations for both plant Zn and deficiency symptoms were very dependent on the variety of corn and the environmental condition