The Role of the 1994-95 Coffee Boom in Uganda's Recovery

This paper reports a CGE analysis that explores the consequences of the 1994-95 rise in the international price of coffee for Uganda´s economy. Evidence is found for a small effect on medium-term growth and poverty reduction. Aid dependence is among the reasons why this effect is not found to be larger. Major beneficiary groups are not only the farmers to which the windfall initially accrued but also urban wage earners and the urban self-employed

Bias, redshift space distortions and primordial nongaussianity of nonlinear transformations: application to Lyman alpha forest

On large scales a nonlinear transformation of matter density field can be viewed as a biased tracer of the density field itself. A nonlinear transformation also modifies the redshift space distortions in the same limit, giving rise to a velocity bias. In models with primordial nongaussianity a nonlinear transformation generates a scale dependent bias on large scales. We derive analytic expressions for these for a general nonlinear transformation. These biases can be expressed entirely in terms of the one point distribution function (PDF) of the final field and the parameters of the transformation. Our analysis allows one to devise nonlinear transformations with nearly arbitrary bias properties, which can be used to increase the signal in the large scale clustering limit. We apply the results to the ionizing equilibrium model of Lyman-alpha forest, in which Lyman-alpha flux F is related to the density perturbation delta via a nonlinear transformation. Velocity bias can be expressed as an average over the Lyman-alpha flux PDF. At z=2.4 we predict the velocity bias of -0.1, compared to the observed value of -0.13 +/- 0.03. Bias and primordial nongaussianity bias depend on the parameters of the transformation. Measurements of bias can thus be used to constrain these parameters, and for reasonable values of the ionizing background intensity we can match the predictions to observations. Matching to the observed values we predict the ratio of primordial nongaussianity bias to bias to have the opposite sign and lower magnitude than the corresponding values for the highly biased galaxies, but this depends on the model parameters and can also vanish or change the sign.Comment: 18 pages, 1 figur

Broken Symmetry as a Stabilizing Remnant

The Goldberger-Wise mechanism enables one to stabilize the length of the warped extra dimension employed in Randall-Sundrum models. In this work we generalize this mechanism to models with multiple warped throats sharing a common ultraviolet brane. For independent throats this generalization is straight forward. If the throats possess a discrete interchange symmetry like Z_n the stabilizing dynamics may respect the symmetry, resulting in equal throat lengths, or they may break it. In the latter case the ground state of an initially symmetric configuration is a stabilized asymmetric configuration in which the throat lengths differ. We focus on two- (three-) throat setups with a Z_2 (Z_3) interchange symmetry and present stabilization dynamics suitable for either breaking or maintaining the symmetry. Though admitting more general application, our results are relevant for existing models in the literature, including the two throat model with Kaluza-Klein parity and the three throat model of flavor based on a broken Z_3 symmetry.Comment: 23 pages; v2 minor cosmetic chang

Modelling the alumina abundance of oxygen-rich evolved stars in the Large Magellanic Cloud

In order to determine the composition of the dust in the circumstellar envelopes of oxygen-rich asymptotic giant branch (AGB) stars we have computed a grid of modust radiative-transfer models for a range of dust compositions, mass-loss rates, dust shell inner radii and stellar parameters. We compare the resulting colours with the observed oxygen-rich AGB stars from the SAGE-Spec Large Magellanic Cloud (LMC) sample, finding good overall agreement for stars with a mid-infrared excess. We use these models to fit a sample of 37 O-rich AGB stars in the LMC with optically thin circumstellar envelopes, for which 5$-$35-$\mu$m Spitzer infrared spectrograph (IRS) spectra and broadband photometry from the optical to the mid-infrared are available. From the modelling, we find mass-loss rates in the range $\sim 8\times10^{-8}$ to $5\times10^{-6}$ M$_{\odot}\ \mathrm{yr}^{-1}$, and we show that a grain mixture consisting primarily of amorphous silicates, with contributions from amorphous alumina and metallic iron provides a good fit to the observed spectra. Furthermore, we show from dust models that the AKARI [11]$-$[15] versus [3.2]$-$[7] colour-colour diagram, is able to determine the fractional abundance of alumina in O-rich AGB stars.Comment: 22 pages, 17 figures, accepted MNRA

Living with Phenylketonuria: lessons from the PKU community

Introduction: We report the practical, social and psychological issues of living with phenylketonuria (PKU) from one of the largest surveys that has been completed by both adults with PKU and parents/caregivers of children. Methods: In the UK, parents/caregivers of children and adults with PKU were invited to complete an online survey between November 2017 to January 2018 by the NSPKU (National Society for Phenylketonuria). Results: 631 participants (adults, n=338; parents/caregivers of children, n=293) with PKU completed the questionnaire. Problems experienced by children with PKU were: difficulty with maintaining focus (48%,n=114/236), educational difficulties (28%, n=67/236), anxiety or depression (29%, n=68/236), and gastrointestinal symptoms (34%, n=97/282). Fifty one per cent (n=120/236) described social exclusion; 17% (n=41/236) had relationship issues with friends or family. Problems experienced by adults were: depression or anxiety (52%, n=148/286), difficulty maintaining focus (54%, n=154/286), and low mood (54%, n=180/334). Difficulties were experienced with relationships (34%, n=96/286); social exclusion (44%, n=126/286); and gastrointestinal issues (n=34%, n=112/334). Common medications used included antidepressants (40%, n=131/331) and anxiolytics (18%, n=60/334). Discussions: Adults with PKU or caregivers/parents of children identified significant neurocognitive, mental health and general health issues. Limits on socialisation, perception of social isolation and dietary stigma are major obstacles which are difficult to overcome with conventional dietary management