Willingness to pay for treatment with highly active antiretroviral (HAART) drugs: a rural case study in Cameroon

This paper reports on the willingness of HIV/AIDS patients to pay for the most affordable triple therapy combination of antiretrovirals in a local setting in Cameroon. Questionnaires were used to evaluate willingness to pay, and patients who could still afford their medication 6 months after the survey were also investigated, to give an indication of actual ability to pay. In addition, oral interviews were carried out for clarification. In all, 84 patients out of a total of 186 were involved in the study. Results indicated that more men (39%) were willing to pay than women (22%), although more women (56%) were afflicted than men.Willingness to pay was directly dependent on cost with 69%, 22% and 9% of respondents indicating willingness to pay $1,$2 and $3 a day respectively. After 6 months of treatment, 22SAHARA-J (2004) 1(2): 107-113 Keywords: HIV/AIDS, treatment, access to antiretrovirals, drug costs, affordability. RÉSUMÉ Cette communication porte sur une bonne volonté des patients souffrants du VIH/SIDA à payer un prix assez abordable de la thérapie triple des anti-rétroviraux dans un milieu rural au Cameroun. Des questionnaires ont été utilisés afin d'évaluer cette bonne volonté à payer les médicaments. De plus, les patients qui avaient les moyens d'acheter leurs médicaments 6 mois après ces épreuves furent interviewés également. En plus de cela, les patients ont été interviewés avec le but d'obtenir des éclaircissements. Parmi les 186 patients, 84 participaient à l'étude. Les résultats de cette étude ont démontré que davantage d'hommes (39$1, $2 et$3 par jour respectivement. Au bout d'une période de 6 mois de traitement, 22% de patients étaient encore en thérapie. Une majorité de patients ont arrêté le traitement au bout de 6 mois faute de manque d'argent. En dehors du coût, le stigmate, l'incrédulité et les effets secondaires des médicaments étaient les facteurs principaux qui étaient contre la volonté de payer. Il est conseillé d'améliorer les services de consultation, de fournir de l'information, de réduire le coût de médicaments ainsi que les essais en laboratoire et l'élaboration des programmes de déstigmatisation afin d'améliorer la capacité de patients à payer pour les anti-rétroviraux. SAHARA-J (2004) 1(2): 107-113 Mots clés: le VIH/SIDA, le traitement, l'accès aux anti-rétroviraux, le coût de médicaments, avoir des moyens d'acheter

Confronting Grand Challenges in Environmental Fluid Dynamics

Environmental fluid dynamics underlies a wealth of natural, industrial and, by extension, societal challenges. In the coming decades, as we strive towards a more sustainable planet, there are a wide range of grand challenge problems that need to be tackled, ranging from fundamental advances in understanding and modeling of stratified turbulence and consequent mixing, to applied studies of pollution transport in the ocean, atmosphere and urban environments. A workshop was organized in the Les Houches School of Physics in France in January 2019 with the objective of gathering leading figures in the field to produce a road map for the scientific community. Five subject areas were addressed: multiphase flow, stratified flow, ocean transport, atmospheric and urban transport, and weather and climate prediction. This article summarizes the discussions and outcomes of the meeting, with the intent of providing a resource for the community going forward

The dynamic trophic niche of an island bird of prey

Optimal foraging theory predicts an inverse relationship between the availability of preferred prey and niche width in animals. Moreover, when individuals within a population have identical prey preferences and preferred prey is scarce, a nested pattern of trophic niche is expected if opportunistic and selective individuals can be identified. Here, we examined intraspecific variation in the trophic niche of a resident population of striated caracara (Phalcoboenus australis) on Isla de los Estados (Staten Island), Argentina, using pellet and stable isotope analyses. While this raptor specializes on seabird prey, we assessed this population\u27s potential to forage on terrestrial prey, especially invasive herbivores as carrion, when seabirds are less accessible. We found that the isotopic niche of this species varies with season, age, breeding status, and, to a lesser extent, year. Our results were in general consistent with classic predictions of the optimal foraging theory, but we also explore other possible explanations for the observed pattern. Isotopic niche was broader for groups identified a priori as opportunistic (i.e., nonbreeding adults during the breeding season and the whole population during the nonbreeding season) than it was for individuals identified a priori as selective. Results suggested that terrestrial input was relatively low, and invasive mammals accounted for no more than 5% of the input. The seasonal pulse of rockhopper penguins likely interacts with caracara\u27s reproductive status by constraining the spatial scale on which individuals forage. Niche expansion in spatially flexible individuals did not reflect an increase in terrestrial prey input; rather, it may be driven by a greater variation in the types of marine prey items consumed

The biogeography of Striated Caracaras Phalcoboenus australis

This thesis defines and offers explanations for the distribution, range, and behavior of Striated Caracaras, coastal raptors of far southern South America. Like other caracara species, Striated Caracaras are relatively social, nest in dense aggregations where food is abundant, and feed largely by scavenging and opportunism. Unlike other caracaras, however, their distribution and range are severely restricted; they live only on the outermost islands of the Falklands/Malvinas archipelago and the Fuego-Patagonian islands of southernmost Argentina and Chile. Striated Caracaras' morphological differences from their closest relatives in the genus Phalcoboenus (which inhabit alpine habitats in the Andes) suggest a period of isolation from their sister species, resulting in speciation by vicariance. A possible mechanism for this isolation is the Patagonian Ice Sheet, which spread over much of southern South America during glacial epochs. During these periods, the sub-Antarctic Falkland archipelago and islands to the south and east of Tierra del Fuego appear to have remained largely ice-free, and probably acted as glacial refuges for colonial seabirds and pinnipeds, as well as for the ancestors of Striated Caracaras. On these islands, Striated Caracaras developed a dependence on the food resources that seabird and pinniped colonies provide, and a preference for their habitat - seacoasts fringed with the giant grass Paradiochloa flabellata. In these coastal environments, selection probably favored the tools that Striated Caracaras use today to exploit the seabird colonies' resources. These tools include large size (to handle large prey species), strong talons and bills, ease of movement on the ground (both for foraging in seabird colonies and precise mobility in near-constant strong winds), and good night vision (to capture burrowing petrels as they return to colonies at night). The caracaras' curious, opportunistic nature (to which they are ancestrally disposed) would have been preserved and perhaps enhanced, due to the necessity of investigating any potential resource during winter months when seabird colonies are vacant. A philopatric tendency might also have developed, as outside of seabird colonies food is scarce and chances of breeding are slim. Isolation in the islands' relatively simple ecosystems probably had another evolutionary effect, typical among island species - it deprived caracaras of defensive adaptations they might have once possessed, including wariness toward potential predators and nesting in inaccessible locations. The result was "ecological naivete", a phenomenon in which species that evolve in simple ecosystems lose (or simply lack) behavioral and morphological traits necessary for survival in more complex environments. Striated Caracaras demonstrated this naivete in encounters with humans in the 19th and 20th centuries, whom the birds approached without fear and by whom they were heavily persecuted. Even after decades of persecution by farmers in the Falklands, Striated Caracaras "had not learnt that man is dangerous" (J Hamilton 1922). They remain so today. A tourist guidebook refers to the birds as "charmingly tame"; islanders are more likely to call them "cheeky" but are increasingly tolerant of them, as wildlife tourism has become a major source of income. The caracaras' ecological naivete also probably restricts them from the more complex South American mainland, where mammalian predators (including humans) and other caracara species are common and food sources are not as concentrated or dependable as the coastal seabirds and pinnipeds. Thus, Striated Caracaras' preference for a habitat and resource set to which they are well-adapted, combined with the loss of defensive behaviors that might protect them from the hazards of the mainland, may leave them essentially "trapped" within their current range. Present-day threats to Striated Caracaras include habitat destruction due to exotic predators and browsers, threats from fisheries and global climate change to the seabirds and marine ecosystems on which the caracaras depend, and the intrinsic genetic pressures of the caracaras' small population size.Geography and the Environmen

A settling-driven instability in two-component, stably stratified fluids

We analyse the linear stability of stably stratified fluids whose density depends on two scalar fields where one of the scalar fields is unstably stratified and involves a settling velocity. Such conditions may be found, for example, in flows involving the transport of sediment in addition to heat or salt. A linear stability analysis for constant-gradient base states demonstrates that the settling velocity generates a phase shift between the perturbation fields of the two scalars, which gives rise to a novel, settling-driven instability mode. This instability mechanism favours the growth of waves that are inclined with respect to the horizontal. It is active for all density and diffusivity ratios, including for cases in which the two scalars diffuse at identical rates. If the scalars have unequal diffusivities, it competes with the elevator mode waves of the classical double-diffusive instability. We present detailed linear stability results as a function of the governing dimensionless parameters, including for lateral gradients of the base state density fields that result in predominantly horizontal intrusion instabilities. Highly resolved direct numerical simulation results serve to illustrate the nonlinear competition of the various instabilities for such flows in different parameter regimes

Layer formation in sedimentary fingering convection

When particles settle through a stable temperature or salinity gradient they can drive an instability known as sedimentary fingering convection. This phenomenon is thought to occur beneath sediment-rich river plumes in lakes and oceans, in the context of marine snow where decaying organic materials serve as the suspended particles or in the atmosphere in the presence of aerosols or volcanic ash. Laboratory experiments of Houk & Green (Deep-Sea Res., vol. 20, 1973, pp. 757–761) and Green (Sedimentology, vol. 34(2), 1987, pp. 319–331) have shown sedimentary fingering convection to be similar to the more commonly known thermohaline fingering convection in many ways. Here, we study the phenomenon using three-dimensional direct numerical simulations. We find evidence for layer formation in sedimentary fingering convection in regions of parameter space where it does not occur for non-sedimentary systems. This is due to two complementary effects. Sedimentation affects the turbulent fluxes and broadens the region of parameter space unstable to the \unicode[STIX]{x1D6FE}-instability (Radko, J. Fluid Mech., vol. 497, 2003, pp. 365–380) to include systems at larger density ratios. It also gives rise to a new layering instability that exists in \unicode[STIX]{x1D6FE}-stable regimes. The former is likely quite ubiquitous in geophysical systems for sufficiently large settling velocities, while the latter probably grows too slowly to be relevant, at least in the context of sediments in water