When is a problem a research problem?

Various definitions of and approaches to research and research problems are explored with numerous examples given. Guiding criteria for applied research are also discussed, along with potential pitfalls, the role of intuition in the process, and the qualities that are needed to make a good researcher.published or submitted for publicatio

On surface-symmetric spacetimes with collisionless and charged matter

Some future global properties of cosmological solutions for the Einstein-Vlasov-Maxwell system with surface symmetry are presented. Global existence is proved, the homogeneous spacetimes are future complete for causal trajectories, and the same is true for inhomogeneous plane-symmetric solutions with small initial data. In the latter case some decay properties are also obtained at late times. Similar but slightly weaker results hold for hyperbolic symmetry.Comment: 34 pages, version to be published in AH

THE ECONOMICS OF GREENING THE SOUTH AFRICAN NATIONAL ARTS FESTIVAL

The paper analyzes the broad history underpinning the concept of sustainable development and its context within the events industry and specifically with regards to the South African National Arts Festival. A pilot contingent valuation study conducted at the 2010 National Arts Festival determined that the average visitor was willing to pay an extra ZAR 2.30 (approximately US$ 0.30) per ticket for a recycling programme to be established to process the waste generated by the event. While the paper concluded that the theoretical basis of the study was sound, a larger sample size would have been preferred so as to enhance the model‘s predictive powercontingent valuation, environmental externalities, event greening, South African National Arts Festival, sustainable development, willingness to pay, Environmental Economics and Policy, Public Economics,

Popular and/or Prestigious? Measures of Scholarly Esteem

Citation analysis does not generally take the quality of citations into account: all citations are weighted equally irrespective of source. However, a scholar may be highly cited but not highly regarded: popularity and prestige are not identical measures of esteem. In this study we define popularity as the number of times an author is cited and prestige as the number of times an author is cited by highly cited papers. Information Retrieval (IR) is the test field. We compare the 40 leading researchers in terms of their popularity and prestige over time. Some authors are ranked high on prestige but not on popularity, while others are ranked high on popularity but not on prestige. We also relate measures of popularity and prestige to date of Ph.D. award, number of key publications, organizational affiliation, receipt of prizes/honors, and gender.Comment: 26 pages, 5 figure

Asymptotically Schroedinger Space-Times: TsT Transformations and Thermodynamics

We study the complete class of 5-dimensional asymptotically Schroedinger space-times that can be obtained as the TsT transform of a 5-dimensional asymptotically AdS space-time. Based on this we identify a conformal class of Schroedinger boundaries. We use a Fefferman-Graham type expansion to study the on-shell action for this class of asymptotically Schroedinger space-times and we show that its value is TsT invariant. In the second part we focus on black hole space-times and prove that black hole thermodynamics is also TsT invariant. We use this knowledge to argue that thermal global Schroedinger space-time at finite chemical potential undergoes a Hawking-Page type phase transition.Comment: References adde

Using phonetic constraints in acoustic-to-articulatory inversion

The goal of this work is to recover articulatory information from the speech signal by acoustic-to-articulatory inversion. One of the main difficulties with inversion is that the problem is underdetermined and inversion methods generally offer no guarantee on the phonetical realism of the inverse solutions. A way to adress this issue is to use additional phonetic constraints. Knowledge of the phonetic caracteristics of French vowels enable the derivation of reasonable articulatory domains in the space of Maeda parameters: given the formants frequencies (F1,F2,F3) of a speech sample, and thus the vowel identity, an "ideal" articulatory domain can be derived. The space of formants frequencies is partitioned into vowels, using either speaker-specific data or generic information on formants. Then, to each articulatory vector can be associated a phonetic score varying with the distance to the "ideal domain" associated with the corresponding vowel. Inversion experiments were conducted on isolated vowels and vowel-to-vowel transitions. Articulatory parameters were compared with those obtained without using these constraints and those measured from X-ray data

Particle Number and 3D Schroedinger Holography

We define a class of space-times that we call asymptotically locally Schroedinger space-times. We consider these space-times in 3 dimensions, in which case they are also known as null warped AdS. The boundary conditions are formulated in terms of a specific frame field decomposition of the metric which contains two parts: an asymptotically locally AdS metric and a product of a lightlike frame field with itself. Asymptotically we say that the lightlike frame field is proportional to the particle number generator N regardless of whether N is an asymptotic Killing vector or not. We consider 3-dimensional AlSch space-times that are solutions of the massive vector model. We show that there is no universal Fefferman-Graham (FG) type expansion for the most general solution to the equations of motion. We show that this is intimately connected with the special role played by particle number. Fefferman-Graham type expansions are recovered if we supplement the equations of motion with suitably chosen constraints. We consider three examples. 1). The massive vector field is null everywhere. The solution in this case is exact as the FG series terminates and has N as a null Killing vector. 2). N is a Killing vector (but not necessarily null). 3). N is null everywhere (but not necessarily Killing). The latter case contains the first examples of solutions that break particle number, either on the boundary directly or only in the bulk. Finally, we comment on the implications for the problem of holographic renormalization for asymptotically locally Schroedinger space-times.Comment: 56 pages, v3: matches version published in JHE

Investigating the Sources of Agricultural Growth in Africa: Factor Accumulation, Total Factor Productivity, and Technology Absorption

This paper investigates sources and determinants of agricultural growth in Africa, concentrating on the growth path during the last three decades. The analysis employs the broader framework provided by empirical growth literature and recent developments in Total Factor Productivity (TFP) measurement to search for fundamental determinants of growth in African agriculture. One main contribution and new findings in this analysis is the quantification of the contribution of the productivity growth and the contribution of different inputs such as land, labor, tractor and fertilizer in the agricultural growth. Growth accounting computation highlights the fact that factor accumulation rather than TFP accounts for a large share of agricultural output growth and fertilizer has been the most statistically important physical input contributor to agricultural growth. The study also highlights the extent to which agricultural growth contributors vary in relation with different country conditions, institutions and politico-historical factors.Growth accounting, TFP, Factor accumulation, Capital absorption, Africa, Agricultural and Food Policy, Agricultural Finance, Community/Rural/Urban Development, Demand and Price Analysis, Farm Management, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, International Relations/Trade, Land Economics/Use, Livestock Production/Industries, Marketing, Productivity Analysis, Research and Development/Tech Change/Emerging Technologies, N50, O47, D24,