The Macroeconomic Consequences of Renouncing to Universal Access to Antiretroviral Treatment for HIV in Africa: A Micro-Simulation Model

AIM: Previous economic literature on the cost-effectiveness of antiretroviral treatment (ART) programs has been mainly focused on the microeconomic consequences of alternative use of resources devoted to the fight against the HIV pandemic. We rather aim at forecasting the consequences of alternative scenarios for the macroeconomic performance of countries. METHODS: We used a micro-simulation model based on individuals aged 15-49 selected from nationally representative surveys (DHS for Cameroon, Tanzania and Swaziland) to compare alternative scenarios : 1-freezing of ART programs to current levels of access, 2- universal access (scaling up to 100% coverage by 2015, with two variants defining ART eligibility according to previous or current WHO guidelines). We introduced an "artificial" ageing process by programming methods. Individuals could evolve through different health states: HIV negative, HIV positive (with different stages of the syndrome). Scenarios of ART procurement determine this dynamics. The macroeconomic impact is obtained using sample weights that take into account the resulting age-structure of the population in each scenario and modeling of the consequences on total growth of the economy. RESULTS: Increased levels of ART coverage result in decreasing HIV incidence and related mortality. Universal access to ART has a positive impact on workers' productivity; the evaluations performed for Swaziland and Cameroon show that universal access would imply net cost-savings at the scale of the society, when the full macroeconomic consequences are introduced in the calculations. In Tanzania, ART access programs imply a net cost for the economy, but 70% of costs are covered by GDP gains at the 2034 horizon, even in the extended coverage option promoted by WHO guidelines initiating ART at levels of 350 cc/mm(3) CD4 cell counts. CONCLUSION: Universal Access ART scaling-up strategies, which are more costly in the short term, remain the best economic choice in the long term. Renouncing or significantly delaying the achievement of this goal, due to "legitimate" short term budgetary constraints would be a misguided choice

Limits to reproduction and seed size-number trade-offs that shape forest dominance and future recovery

International audienceThe relationships that control seed production in trees are fundamental to understanding the evolution of forest species and their capacity to recover from increasing losses to drought, fire, and harvest. A synthesis of fecundity data from 714 species worldwide allowed us to examine hypotheses that are central to quantifying reproduction, a foundation for assessing fitness in forest trees. Four major findings emerged. First, seed production is not constrained by a strict trade-off between seed size and numbers. Instead, seed numbers vary over ten orders of magnitude, with species that invest in large seeds producing more seeds than expected from the 1:1 trade-off. Second, gymnosperms have lower seed production than angiosperms, potentially due to their extra investments in protective woody cones. Third, nutrient-demanding species, indicated by high foliar phosphorus concentrations, have low seed production. Finally, sensitivity of individual species to soil fertility varies widely, limiting the response of community seed production to fertility gradients. In combination, these findings can inform models of forest response that need to incorporate reproductive potential

Limits to reproduction and seed size-number tradeoffs that shape forest dominance and future recovery

The relationships that control seed production in trees are fundamental to understanding the evolution of forest species and their capacity to recover from increasing losses to drought, fire, and harvest. A synthesis of fecundity data from 714 species worldwide allowed us to examine hypotheses that are central to quantifying reproduction, a foundation for assessing fitness in forest trees. Four major findings emerged. First, seed production is not constrained by a strict trade-off between seed size and numbers. Instead, seed numbers vary over ten orders of magnitude, with species that invest in large seeds producing more seeds than expected from the 1:1 trade-off. Second, gymnosperms have lower seed production than angiosperms, potentially due to their extra investments in protective woody cones. Third, nutrient-demanding species, indicated by high foliar phosphorus concentrations, have low seed production. Finally, sensitivity of individual species to soil fertility varies widely, limiting the response of community seed production to fertility gradients. In combination, these findings can inform models of forest response that need to incorporate reproductive potential

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Applications of wide Band Time Domain EM Measurements in Mineral Exploration

Electromagnetic prospecting measurements must be made over a wider band of frequencies if they are to be effective in terrains with complicated conductivity structures. A system (UTEM) was designed to do such measurements systematically and practically in the time domain. It is a ground method using a large transmitter loop and a single receiver coil. The transmitted current has a precise triangular waveform at a frequency of 30 Hz. In the receiver, there are eight sampling channels corresponding to delay times decreasing according to a binary geometric progression. The UTEM system has many unusual characteristics: it can measure both electric and magnetic fields; the transmitted waveform concentrates the power at lower frequencies and has no off times; the measuring channels sample virtually the whole waveform. Field measurements were made at five test sites. The data from a field survey in a stratified environment were interpreted by developing numerical methods for inverting the observed data in terms of layered models. In order to explain the other field results, a variety of idealized models were studied by time-domain scale models measurements and by conversion of frequency domain model data. Very few of the field responses can be completely explained in terms of free-air models. However, the late portion of measured transient decays can often be explained in this fashion. The more complicated responses which occur at early sampling times can be explained in terms of two main effects -- "blanking" and "current gathering". These were studied by means of idealized models. The "blanking" effect is the disappearance of the response at early times caused by shielding of a local conductor by a conductive overburden which is not in contact with it. The "current gathering" effect is an enhancement of the response at early times (but after "blanking") which is caused by the channelling of regionally induced host-rock currents into a local conductor. Current gathering is the most prevalent in the field responses. In the documented examples, it appears to be due to the presence of a diffuse conductive "halo" surrounding the main (sulphide) conductors. Some unexpected field responses which appeared on the later channels have been tentatively explained as inductive induced polarization (IIP) effects. The computed responses of some simple polarizable models explain some of the features of the field responses but they indicate that with magnetic field measurements, IIP effects would be detectable only for high chargeabilities. IIP effects in electric field data are more detectable. Since these cannot be explained as magnetic responses, the observed electric field responses are regarded as more conclusive field evidences of IIP responses. The electric field IIP responses are apparently excited by regional host rock currents being channeled into metallic conductors and may be used to identify metallic conductors.Ph.D

Cours de mise à niveau pour allophones: éléments de réflexion, 1re partie /

Tiré de l'écran-titre (visionné le 27 mars 2013)