Quantum searching amidst uncertainty

Consider a database most of whose entries are marked but the precise fraction of marked entries is not known. What is known is that the fraction of marked entries is 1-X, where X is a random variable that is uniformly distributed in the range (0,X_0) (X_0 is a small number). The problem is to try to select a marked item from the database in a single query. If the algorithm selects a marked item, it succeeds, else if it selects an unmarked item, it makes an error. How low can we make the probability of error? The best possible classical algorithm can lower the probability of error to O((X_0)^2). The best known quantum algorithms for this problem could also only lower the probability of error to O((X_0)^2). Using a recently invented quantum search technique, this paper gives an algorithm that reduces the probability of error to O((X_0)^3). The algorithm is asymptotically optimal.Comment: 10 page

Matching seeds to needs: Using informatics to select crop varieties adapted to future climates

Poster presented at Agriculture and Rural Development Day 2009. Copenhagen (Denmark). 12 Dec 2009

Developmental guidance and student acquisition of social competence.

In a changing world, it is increasingly important to articulate what are the social emotional competencies that students leaving secondary schools need to acquire in order to be effective learners and citizens and how schools can facilitate the acquisition of such competencies. There is an emerging consensus that CASEL [1] has identified five of those core competencies. They are a) self-awareness, b) self-management, c) social awareness, d) relationship skills and e) responsible decision-making. There is not, however, a consensus as to how schools can facilitate the acquisition of these competencies. This paper will argue that each community needs to articulate the competencies they expect from their children and ensure that their schools implement a program of developmental guidance that helps them acquire these competencies. Developmental guidance is a combination of curriculum that teaches these competencies, experiences through which students can put them into practice, a systematic approach to developing and implementing a post-secondary plan for each student, and a way to assess the success of such an approach. In the same way that competence in literacy and numeracy is developed over a child’s career in school through a series of increasingly complex coursework, we need to implement systematic developmental guidance in all schools so that we more effectively prepare our children to take their place in a world that is changing as a result of technological and social developments. There are several barriers to implementing effective developmental guidance programs. One is the lack of consensus as to the role of schools in providing such training. Another is the lack of consensus as to what are those desired competencies. A third is the lack of resources made available to support such implementation.Accepted manuscrip

An intrusion layer in stationary incompressible fluids Part 2: A solitary wave

The propagation of a solitary wave in a horizontal fluid layer is studied. There is an interfacial free surface above and below this intrusion layer, which is moving at constant speed through a stationary density-stratified fluid system. A weakly nonlinear asymptotic theory is presented, leading to a Korteweg-de Vries equation in which the two fluid interfaces move oppositely. The intrusion layer solitary wave system thus forms a widening bulge that propagates without change of form. These results are confirmed and extended by a fully nonlinear solution, in which a boundary-integral formulation is used to solve the problem numerically. Limiting profiles are approached, for which a corner forms at the crest of the solitary wave, on one or both of the interfaces

Unsteady draining of a fluid from a circular tank

Three-dimensional draining flow of a two-fluid system from a circular tank is considered. The two fluids are inviscid and incompressible, and are separated by a sharp interface. There is a circular hole positioned centrally in the bottom of the tank, so that the flow is axially symmetric. The mean position of the interface moves downwards as time progresses, and eventually a portion of the interface is withdrawn into the drain. For narrow drain holes of small radius, the interface above the centre of the drain is pulled down towards the hole. However, for drains of larger radius the portion of the interface above the drain edge is drawn down first, rather than the central section. Non-linear results are obtained with a novel spectral technique, and are also compared against the predictions of linearized theory. Unstable Rayleigh-Taylor type flows, in which the upper fluid is heavier than the lower one, are also discussed

An intrusion layer in stationary incompressible fluids Part 2: A solitary wave

The propagation of a solitary wave in a horizontal fluid layer is studied. There is an interfacial free surface above and below this intrusion layer, which is moving at constant speed through a stationary density-stratified fluid system. A weakly nonlinear asymptotic theory is presented, leading to a Korteweg-de Vries equation in which the two fluid interfaces move oppositely. The intrusion layer solitary wave system thus forms a widening bulge that propagates without change of form. These results are confirmed and extended by a fully nonlinear solution, in which a boundary-integral formulation is used to solve the problem numerically. Limiting profiles are approached, for which a corner forms at the crest of the solitary wave, on one or both of the interfaces

WDVV equations for pure Super-Yang-Mills theory

In the literature, there are two proofs that the prepotential of $N=2$ pure Super-Yang-Mills theory satisfies the Witten-Dijkgraaf-Verlinde-Verlinde (WDVV) equations. We show that these two methods are in fact equivalent. \u

AGRICULTURE AS A DRIVING FORCE OF ECONOMIC DEVELOPMENT: SUGGESTIONS FOR AGRICULTURAL DEVELOPMENT POLICY IN SOUTHERN AFRICA

The purpose of the paper is to explain the process by which modernisation of the agricultural sector by introducing new production technology into the sector serves as driving force of general economic development, with the social rate of return on these investments being very high, while the benefits of the development will be widespread in the economy, and generally in favour of the poor. Furthermore policies are discussed with the aim of increasing productivity and per capita income of rural people in Southern Africa.Agricultural and Food Policy, International Development,

Halogenated indole-3-acetic acids as oxidatively activated prodrugs with potential for targeted cancer therapy

Peer reviewe