13 research outputs found
Evaluation de la rentabilite et de la competitivite de la chaine de valeur gomme arabique dans lâamelioration des conditions de vie des populations au Sahel du Burkina Faso
LâĂ©tude a eu pour objectif dâĂ©valuer la rentabilitĂ© et la compĂ©titivitĂ© de la chaine de valeurs gomme arabique au Sahel du Burkina Faso. Les donnĂ©es ont Ă©tĂ© collectĂ©es auprĂšs de 40 producteurs, de 20 collecteurs, de lâassociation des exportateurs de gomme arabique et des services douaniers du Burkina Faso. Des donnĂ©es aussi bien secondaires que primaires ont Ă©tĂ© collectĂ©es. Les donnĂ©es primaires ont Ă©tĂ© collectĂ©es Ă lâaide de questionnaires structurĂ©s, Ă raison dâun questionnaire par catĂ©gorie dâacteurs. Les logiciels Excel et Value Chain Analysis (VCA) version 10 ont Ă©tĂ© utilisĂ©s pour la saisie et le calcul des indicateurs de rentabilitĂ© et de compĂ©titivitĂ©. La Matrice dâAnalyse des Politiques (MAP) a Ă©tĂ© utilisĂ©e comme outil dâanalyse. Des rĂ©sultats obtenus, il se dĂ©gage que la chaine de valeurs gomme arabique est financiĂšrement et Ă©conomiquement rentable. Lâanalyse des indicateurs de compĂ©titivitĂ© fait ressortir un avantage comparatif Ă produire la gomme arabique dans le Sahel du Burkina Faso. Les coĂ»ts en ressources domestiques montrent que tous les agents Ă©conomiques utilisent les ressources domestiques de maniĂšre rationnelle. Les profits ainsi gĂ©nĂ©rĂ©s permettraient un accroissement de la production de la gomme arabique qui impacte positivement sur lâamĂ©lioration des conditions de vie des exploitants du Sahel du Burkina Faso.Mots clĂ©s : Gomme arabique, rentabilitĂ© financiĂšre, rentabilitĂ© Ă©conomique, compĂ©titivitĂ©, Sahel du Burkina Faso
Simultaneous measurement of muon neutrino charged-current single production in CH, C, HO, Fe, and Pb targets in MINERvA
Neutrino-induced charged-current single production in the
resonance region is of considerable interest to
accelerator-based neutrino oscillation experiments. In this work, high
statistics differential cross sections are reported for the semi-exclusive
reaction nucleon(s) on scintillator, carbon,
water, iron, and lead targets recorded by MINERvA using a wide-band
beam with \left \approx 6~GeV. Suppression of the cross
section at low and enhancement of low are observed in both light
and heavy nuclear targets compared to phenomenological models used in current
neutrino interaction generators. The cross-section ratios for iron and lead
compared to CH across the kinematic variables probed are 0.8 and 0.5
respectively, a scaling which is also not predicted by current generators.Comment: 6 pages, 6 figures, 117 pages of supplementary material; submitted to
Physical Review Letter
Safety and immunogenicity of the two-dose heterologous Ad26.ZEBOV and MVA-BN-Filo Ebola vaccine regimen in children in Sierra Leone: a randomised, double-blind, controlled trial
BackgroundâChildren account for a substantial proportion of cases and deaths from Ebola virus disease. We aimed to assess the safety and immunogenicity of a two-dose heterologous vaccine regimen, comprising the adenovirus type 26 vector-based vaccine encoding the Ebola virus glycoprotein (Ad26.ZEBOV) and the modified vaccinia Ankara vectorbased vaccine, encoding glycoproteins from the Ebola virus, Sudan virus, and Marburg virus, and the nucleoprotein from the Tai Forest virus (MVA-BN-Filo), in a paediatric population in Sierra Leone.
MethodsâThis randomised, double-blind, controlled trial was done at three clinics in Kambia district, Sierra Leone. Healthy children and adolescents aged 1â17 years were enrolled in three age cohorts (12â17 years, 4â11 years, and 1â3 years) and randomly assigned (3:1), via computer-generated block randomisation (block size of eight), to receive an intramuscular injection of either Ad26.ZEBOV (5 Ă 1010 viral particles; first dose) followed by MVA-BN-Filo (1 Ă 108 infectious units; second dose) on day 57 (Ebola vaccine group), or a single dose of meningococcal quadrivalent (serogroups A, C, W135, and Y) conjugate vaccine (MenACWY; first dose) followed by placebo (second dose) on day 57 (control group). Study team personnel (except for those with primary responsibility for study vaccine preparation), participants, and their parents or guardians were masked to study vaccine allocation. The primary outcome was safety, measured as the occurrence of solicited local and systemic adverse symptoms during 7 days after each vaccination, unsolicited systemic adverse events during 28 days after each vaccination, abnormal laboratory results during the study period, and serious adverse events or immediate reportable events throughout the study period. The secondary outcome was immunogenicity (humoral immune response), measured as the concentration of Ebola virus glycoprotein-specific binding antibodies at 21 days after the second dose. The primary outcome was assessed in all participants who had received at least one dose of study vaccine and had available reactogenicity data, and immunogenicity was assessed in all participants who had received both vaccinations within the protocol-defined time window, had at least one evaluable post-vaccination sample, and had no major protocol deviations that could have influenced the immune response. This study is registered at ClinicalTrials.gov, NCT02509494.
FindingsâFrom April 4, 2017, to July 5, 2018, 576 eligible children or adolescents (192 in each of the three age cohorts) were enrolled and randomly assigned. The most common solicited local adverse event during the 7 days after the first and second dose was injection-site pain in all age groups, with frequencies ranging from 0% (none of 48) of children aged 1â3 years after placebo injection to 21% (30 of 144) of children aged 4â11 years after Ad26.ZEBOV vaccination. The most frequently observed solicited systemic adverse event during the 7 days was headache in the 12â17 years and 4â11 years age cohorts after the first and second dose, and pyrexia in the 1â3 years age cohort after the first and second dose. The most frequent unsolicited adverse event after the first and second dose vaccinations was malaria in all age cohorts, irrespective of the vaccine types. Following vaccination with MenACWY, severe thrombocytopaenia was observed in one participant aged 3 years. No other clinically significant laboratory abnormalities were observed in other study participants, and no serious adverse events related to the Ebola vaccine regimen were reported. There were no treatment-related deaths. Ebola virus glycoprotein-specific binding antibody responses at 21 days after the second dose of the Ebola virus vaccine regimen were observed in 131 (98%) of 134 children aged 12â17 years (9929 ELISA units [EU]/mL [95% CI 8172â12 064]), in 119 (99%) of 120 aged 4â11 years (10 212 EU/mL [8419â12 388]), and in 118 (98%) of 121 aged 1â3 years (22 568 EU/mL [18 426â27 642]).
InterpretationâThe Ad26.ZEBOV and MVA-BN-Filo Ebola vaccine regimen was well tolerated with no safety concerns in children aged 1â17 years, and induced robust humoral immune responses, suggesting suitability of this regimen for Ebola virus disease prophylaxis in children
Safety and long-term immunogenicity of the two-dose heterologous Ad26.ZEBOV and MVA-BN-Filo Ebola vaccine regimen in adults in Sierra Leone: a combined open-label, non-randomised stage 1, and a randomised, double-blind, controlled stage 2 trial
Background
The Ebola epidemics in west Africa and the Democratic Republic of the Congo highlight an urgent need for safe and effective vaccines to prevent Ebola virus disease. We aimed to assess the safety and long-term immunogenicity of a two-dose heterologous vaccine regimen, comprising the adenovirus type 26 vector-based vaccine encoding the Ebola virus glycoprotein (Ad26.ZEBOV) and the modified vaccinia Ankara vector-based vaccine, encoding glycoproteins from Ebola virus, Sudan virus, and Marburg virus, and the nucleoprotein from the Tai Forest virus (MVA-BN-Filo), in Sierra Leone, a country previously affected by Ebola.
Methods
The trial comprised two stages: an open-label, non-randomised stage 1, and a randomised, double-blind, controlled stage 2. The study was done at three clinics in Kambia district, Sierra Leone. In stage 1, healthy adults (aged â„18 years) residing in or near Kambia district, received an intramuscular injection of Ad26.ZEBOV (5Ă1010 viral particles) on day 1 (first dose) followed by an intramuscular injection of MVA-BN-Filo (1Ă108 infectious units) on day 57 (second dose). An Ad26.ZEBOV booster vaccination was offered at 2 years after the first dose to stage 1 participants. The eligibility criteria for adult participants in stage 2 were consistent with stage 1 eligibility criteria. Stage 2 participants were randomly assigned (3:1), by computer-generated block randomisation (block size of eight) via an interactive web-response system, to receive either the Ebola vaccine regimen (Ad26.ZEBOV followed by MVA-BN-Filo) or an intramuscular injection of a single dose of meningococcal quadrivalent (serogroups A, C, W135, and Y) conjugate vaccine (MenACWY; first dose) followed by placebo on day 57 (second dose; control group). Study team personnel, except those with primary responsibility for study vaccine preparation, and participants were masked to study vaccine allocation. The primary outcome was the safety of the Ad26.ZEBOV and MVA-BN-Filo vaccine regimen, which was assessed in all participants who had received at least one dose of study vaccine. Safety was assessed as solicited local and systemic adverse events occurring in the first 7 days after each vaccination, unsolicited adverse events occurring in the first 28 days after each vaccination, and serious adverse events or immediate reportable events occurring up to each participantâs last study visit. Secondary outcomes were to assess Ebola virus glycoprotein-specific binding antibody responses at 21 days after the second vaccine in a per-protocol set of participants (ie, those who had received both vaccinations within the protocol-defined time window, had at least one evaluable post-vaccination sample, and had no major protocol deviations that could have influenced the immune response) and to assess the safety and tolerability of the Ad26.ZEBOV booster vaccination in stage 1 participants who had received the booster dose. This study is registered at ClinicalTrials.gov, NCT02509494.
Findings
Between Sept 30, 2015, and Oct 19, 2016, 443 participants (43 in stage 1 and 400 in stage 2) were enrolled; 341 participants assigned to receive the Ad26.ZEBOV and MVA-BN-Filo regimen and 102 participants assigned to receive the MenACWY and placebo regimen received at least one dose of study vaccine. Both regimens were well tolerated with no safety concerns. In stage 1, solicited local adverse events (mostly mild or moderate injection-site pain) were reported in 12 (28%) of 43 participants after Ad26.ZEBOV vaccination and in six (14%) participants after MVA-BN-Filo vaccination. In stage 2, solicited local adverse events were reported in 51 (17%) of 298 participants after Ad26.ZEBOV vaccination, in 58 (24%) of 246 after MVA-BN-Filo vaccination, in 17 (17%) of 102 after MenACWY vaccination, and in eight (9%) of 86 after placebo injection. In stage 1, solicited systemic adverse events were reported in 18 (42%) of 43 participants after Ad26.ZEBOV vaccination and in 17 (40%) after MVA-BN-Filo vaccination. In stage 2, solicited systemic adverse events were reported in 161 (54%) of 298 participants after Ad26.ZEBOV vaccination, in 107 (43%) of 246 after MVA-BN-Filo vaccination, in 51 (50%) of 102 after MenACWY vaccination, and in 39 (45%) of 86 after placebo injection. Solicited systemic adverse events in both stage 1 and 2 participants included mostly mild or moderate headache, myalgia, fatigue, and arthralgia. The most frequent unsolicited adverse event after the first dose was headache in stage 1 and malaria in stage 2. Malaria was the most frequent unsolicited adverse event after the second dose in both stage 1 and 2. No serious adverse event was considered related to the study vaccine, and no immediate reportable events were observed. In stage 1, the safety profile after the booster vaccination was not notably different to that observed after the first dose. Vaccine-induced humoral immune responses were observed in 41 (98%) of 42 stage 1 participants (geometric mean binding antibody concentration 4784 ELISA units [EU]/mL [95% CI 3736â6125]) and in 176 (98%) of 179 stage 2 participants (3810 EU/mL [3312â4383]) at 21 days after the second vaccination.
Interpretation
The Ad26.ZEBOV and MVA-BN-Filo vaccine regimen was well tolerated and immunogenic, with persistent humoral immune responses. These data support the use of this vaccine regimen for Ebola virus disease prophylaxis in adults
Synchronization of coupled Kuramoto oscillators competing for resources
Populations of oscillators are present throughout nature. Very often
synchronization is observed in such populations if they are allowed to
interact. A paradigmatic model for the study of such phenomena has been the
Kuramoto model. However, considering real oscillations are rarely isochronous
as a function of energy, it is natural to extend the model by allowing the
natural frequencies to vary as a function of some dynamical resource supply.
Beyond just accounting for a dynamical supply of resources, however,
competition over a \emph{shared} resource supply is important in a variety of
biological systems. In neuronal systems, for example, resource competition
enables the study of neural activity via fMRI. It is reasonable to expect that
this dynamical resource allocation should have consequences for the
synchronization behavior of the brain. This paper presents a modified Kuramoto
dynamics which includes additional dynamical terms that provide a relatively
simple model of resource competition among populations of Kuramoto oscillators.
We design a mutlilayer system which highlights the impact of the competition
dynamics, and we show that in this designed system, correlations can arise
between the synchronization states of two populations of oscillators which
share no phase-coupling edges. These correlations are interesting in light of
the often observed variance between functional and structural connectivity
measures in real systems. The model presented here then suggests that some of
the observed discrepancy may be explained by the way in which the brain
dynamically allocates resources to different regions according to demand. If
true, models such as this one provide a theoretical framework for analyzing the
differences between structural and functional measures, and possibly implicate
dynamical resource allocation as an integral part of the neural computation
process.Comment: 12 pages, 2 figure