The link approach to measuring consumer surplus in transport networks

Should one calculate user benefits from changes in door-to-door journeys or from changes in the use of separate links of the network? The second approach is often discarded for its perceived inability to deal with new links and the OD-matrix approach is favoured. Differences arise when the set of used routes changes. A consumer model containing a general static transportation network with explicit non-negativity constraints serves as a basis for welfare measures expressed in shadow prices. The approximation error when applying the link approach need not be too severe. A rehabilitation of the link approach may be in order.

AdS vacua with scale separation from IIB supergravity

Only two kinds of compactification are known that lead to four-dimensional supersymmetric AdS vacua with moduli stabilisation and separation of scales at tree-level. The most studied ones are compactifications of massive IIA supergravity on SU(3) structures with smeared O6 planes, for which a general ten-dimensional expression for the solution in terms of the SU(3) structure was found. Less studied are compactifications of IIB supergravity with smeared O5/O7 planes. In this paper we derive a general ten-dimensional expression for the smeared O5/O7 solutions in terms of SU(2) structures. For a specific choice of orientifold projections, we recover the known examples and we also provide new explicit solutions.Comment: 27 + 16 pages; v2 references added and typos in few equations correcte

Antibranes don't go black

When D-branes are inserted in flux backgrounds of opposite charge, the resulting solution has a certain singularity in the fluxes. Recently it has been argued, using numerical solutions, that for anti-D3 branes in the Klebanov-Strassler background these singularities cannot be cloaked by a horizon, which strongly suggests they are not physical. In this note we provide an analytic proof that the singularity of all codimension-three antibrane solutions (such as anti-D6 branes in massive type IIA supergravity or anti-D3 branes smeared on the T^3 of R^3xT^3 with fluxes) cannot be hidden behind a horizon, and that the charge of black branes with smooth event horizons must have the same sign as the charge of the flux background. Our result indicates that infinitesimally blackening the antibranes immediately triggers brane-flux annihilation, and strengthens the intuition that antibranes placed in flux with positive charge immediately annihilate against it.Comment: 9 pages, 1 figur

Non-home prepared foods : contribution to energy and nutrient intake of consumers living in two low-income areas in Nairobi

Objective: To determine the nutritional importance of non-home prepared foods for men, women and schoolchildren living in two low-income residential areas of Nairobi, and the sources of these non-home prepared foods. Design, setting and subjects: A survey was conducted in Korogocho, a slum area, and Dandora, a low-middle-income residential area. Some 241 men, 254 women and 146 children aged 9 to 14 years were included in the study. Food intake was measured using three 24-hour recalls per individual, with special attention on the sources of all foods consumed. Results: The median proportion of daily energy intake of consumers provided by non-home prepared foods ranged from 13% for schoolchildren in Korogocho to 36% for men in Dandora. The median contribution to fat intake was higher than to energy, but the contributions to iron and vitamin A intakes were lower than to energy intake. Men consumed more non-home prepared foods on weekdays than at the weekend. Intakes of energy and most nutrients were below Kenyan Recommended Daily Intakes in all groups, but similar for consumers and non-consumers. In Korogocho, street foods were the main source of non-home prepared foods. In Dandora, both kiosks and street foods were major sources. Conclusions: Non-home prepared foods are an important source of energy and nutients for men, women and schoolchildren in Nairobi. In Korogocho, street foods, and in Dandora, both kiosks and street foods are the main sources of non-home prepared foods. The adequacy of energy and nutrient intakes does not differ between consumers and non-consumers of non-home prepared foods

Hyperglycemia: causes and consequences

Dekker, J.M. [Promotor]Nijpels, M.G.A.A.M. [Promotor]Alssema, M.J. [Copromotor

Domain walls inside localised orientifolds

The equations of motion of toroidal orientifold compactifications with fluxes are in one-to-one correspondence with gauged supergravity if the orientifold (and D-brane) sources are smeared over the compact space. This smeared limit is identical to the approximation that ignores warping. It is therefore relevant to compare quantities obtained from the gauged supergravity with the true 10d solution with localised sources. In this paper we find the correspondence between BPS domain walls in gauged SUGRA and 10D SUGRA with localised sources. Our model is the simplest orientifold with fluxes we are aware of: an O6/D6 compactification on T^3/Z_2 in massive IIA with H_3-flux. The BPS domain walls correspond to a O6/D6/NS5/D8 bound state. Our analysis reveals that the domain wall energy computed in gauged SUGRA is unaffected by the localisation of the O6/D6 sources.Comment: 26 pages, 1 figur

Localised anti-branes in non-compact throats at zero and finite T

We investigate the 3-form singularities that are typical to anti-brane solutions in supergravity and check whether they can be cloaked by a finite temperature horizon. For anti-D3-branes in the Klebanov-Strassler background, this was already shown numerically to be impossible when the branes are partially smeared. In this paper, we present analytic arguments that also localised branes remain with singular 3-form fluxes at both zero and finite temperature. These results may have important, possibly fatal, consequences for constructions of meta-stable de Sitter vacua through uplifting.Comment: 18 + 9 page