681 research outputs found

    Influence pathways and economic impacts of policy change in the Kenyan dairy sector

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    This study is an ex post assessment of the impact of the revised Kenya dairy policy. It outlines the policy change process, investigates induced behavioral changes at the levels of field regulators and SSMVs (small-scale milk vendors), and estimates economic impacts on producers, SSMVs and consumers. It also provides a strategic assessment of the research and coordinating roles played by ILRI, recognizing that ILRI was only one partner in a complex project with many people and organizations involved, and estimates how much of the overall gains can be attributed to this research/coordination component. It was designed to evaluate the impact of a revised Kenyan dairy policy that encouraged relevant government agencies to engage with SSMVs and, in particular, to explore and analyse the role that research/coordination played in contributing to the policy change and the net benefits to the investment in the policy research component. The study describes the policy, institutional (in the broad sense of ā€˜rules of the gameā€™) and behavioral changes that have occurred in Kenyaā€™s dairy sector and how they occurred and what role the research and coordination component of SDP (Smallholder Dairy Project) played. It quantifies transaction costs and evaluates how reduced transaction costs have impacted the prices paid by consumers and those received by producers. It measures the overall economic benefits of the policy change to consumers, producers and SSMVs, and presents a counterfactual situation, depicting what might have happened if SDP had not been implemented and the dairy policy had not changed

    AN ALTERNATIVE METHOD TO THAT OF THE R6 PROCEDURE FOR THE TREATMENT OF COMBINED PRIMARY AND SECONDARY LOADING

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    ABSTRACT An alternative definition for the assessment point parameter of the R6 defect assessment procedure is proposed, for combined primary and secondary loading. This alternative definition removes the requirement to calculate a plasticity correction factor for secondary stresses, Ļ (or V), used in the conventional R6 definition of . To compare these definitions, both the R6 procedure and the alternative method are presented as Crack Driving Force (CDF) estimation schemes. The required inputs to these estimation schemes have been determined from finite element analyses, for the particular case, of a thick-walled cylinder with a fully circumferential internal defect and subjected to internal pressure and a radial through-wall temperature gradient. Comparisons of CDF estimates with those determined from full inelastic finite element analyses have shown, for the cases studied, that both the R6 and alternative approaches provide conservative estimates of CDF compared to those obtained from finite element analyses, with the degree of conservatism far greater for the conventional R6 approach. Further finite element validation with different geometries, loadings and material properties is required before the alternative procedure could be considered for inclusion in the R6 defect assessment procedure as an alternative to the procedure of the main section of the document

    The HD 93963 A transiting system: A 1.04 d super-Earth and a 3.65 d sub-Neptune discovered by TESS and CHEOPS

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    We present the discovery of two small planets transiting HD 93963A (TOI-1797), a GOV star (M* = 1.109 Ā± 0.043MāŠ™, R* = 1.043 Ā± 0.009 RāŠ™) in a visual binary system. We combined TESS and CHEOPS space-borne photometry with MuSCAT 2 ground-based photometry, ā€˜Alopeke and PHARO high-resolution imaging, TRES and FIES reconnaissance spectroscopy, and SOPHIE radial velocity measurements. We validated and spectroscopically confirmed the outer transiting planet HD 93963 A c, a sub-Neptune with an orbital period of Pc ā‰ˆ 3.65 d that was reported to be a TESS object of interest (TOI) shortly after the release of Sector 22 data. HD 93963 A c has amass of Mc = 19.2 Ā± 4.1 MāŠ• and a radius of Rc = 3.228 Ā± 0.059 RāŠ•, implying a mean density of Ļc = 3.1 Ā± 0.7 g cm-3. The inner object, HD 93963 A b, is a validated 1.04 d ultra-short period (USP) transiting super-Earth that we discovered in the TESS light curve and that was not listed as a TOI, owing to the low significance of its signal (TESS signal-to-noise ratio ā‰ˆ6.7, TESS + CHEOPS combined transit depth Db = 141.5āˆ’8.3+8.5 ppm). We intensively monitored the star with CHEOPS by performing nine transit observations to confirm the presence of the inner planet and validate the system. HD 93963 A b is the first small (Rb = 1.35 Ā± 0.042 RāŠ•) USP planet discovered and validated by TESS and CHEOPS. Unlike planet c, HD 93963 Ab is not significantly detected in our radial velocities (Mb = 7.8 Ā± 3.2 MāŠ•). The two planets are on either side of the radius valley, implying that they could have undergone completely different evolution processes. We also discovered a linear trend in our Doppler measurements, suggesting the possible presence of a long-period outer planet. With a V-band magnitude of 9.2, HD 93963 A is among the brightest stars known to host a USP planet, making it one of the most favourable targets for precise mass measurement via Doppler spectroscopy and an important laboratory to test formation, evolution, and migration models of planetary systems hosting ultra-short period planets

    The atmosphere and architecture of WASP-189 b probed by its CHEOPS phase curve

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    Context. Gas giants orbiting close to hot and massive early-type stars can reach dayside temperatures that are comparable to those of the coldest stars. These ā€˜ultra-hot Jupitersā€™ have atmospheres made of ions and atomic species from molecular dissociation and feature strong day-to-night temperature gradients. Photometric observations at different orbital phases provide insights on the planetā€™s atmospheric properties. Aims. We aim to analyse the photometric observations of WASP-189 acquired with the Characterising Exoplanet Satellite (CHEOPS) to derive constraints on the system architecture and the planetary atmosphere. Methods. We implemented a light-curve model suited for an asymmetric transit shape caused by the gravity-darkened photosphere of the fast-rotating host star. We also modelled the reflective and thermal components of the planetary flux, the effect of stellar oblateness and light-travel time on transit-eclipse timings, the stellar activity, and CHEOPS systematics. Results. From the asymmetric transit, we measure the size of the ultra-hot Jupiter WASP-189 b, Rp = 1.600āˆ’0.016+0.017ā€‰RJ, with a precision of 1%, and the true orbital obliquity of the planetary system, ĪØp = 89.6 Ā± 1.2deg (polar orbit). We detect no significant hotspot offset from the phase curve and obtain an eclipse depth of Ī“ecl = 96.5āˆ’5.0+4.5ā€‰ppm, from which we derive an upper limit on the geometric albedo: Ag < 0.48. We also find that the eclipse depth can only be explained by thermal emission alone in the case of extremely inefficient energy redistribution. Finally, we attribute the photometric variability to the stellar rotation, either through superficial inhomogeneities or resonance couplings between the convective core and the radiative envelope. Conclusions. Based on the derived system architecture, we predict the eclipse depth in the upcoming Transiting Exoplanet Survey Satellite (TESS) observations to be up to ~165 ppm. High-precision detection of the eclipse in both CHEOPS and TESS passbands might help disentangle reflective and thermal contributions. We also expect the right ascension of the ascending node of the orbit to precess due to the perturbations induced by the stellar quadrupole moment J2 (oblateness)

    Presence of Putative Repeat-in-Toxin Gene tosA in Escherichia coli Predicts Successful Colonization of the Urinary Tract

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    Uropathogenic Escherichia coli (UPEC) strains, which cause the majority of uncomplicated urinary tract infections (UTIs), carry a unique assortment of virulence or fitness genes. However, no single defining set of virulence or fitness genes has been found in all strains of UPEC, making the differentiation between UPEC and fecal commensal strains of E.Ā coli difficult without the use of animal models of infection or phylogenetic grouping. In the present study, we consider three broad categories of virulence factors simultaneously to better define a combination of virulence factors that predicts success in the urinary tract. A total of 314 strains of E.Ā coli, representing isolates from fecal samples, asymptomatic bacteriuria, complicated UTIs, and uncomplicated bladder and kidney infections, were assessed by multiplex PCR for the presence of 15 virulence or fitness genes encoding adhesins, toxins, and iron acquisition systems. The results confirm previous reports of gene prevalence among isolates from different clinical settings and identify several new patterns of gene associations. One gene, tosA, a putative repeat-in-toxin (RTX) homolog, is present in 11% of fecal strains but 25% of urinary isolates. Whereas tosA-positive strains carry an unusually high number (11.2) of the 15 virulence or fitness genes, tosA-negative strains have an average of only 5.4 virulence or fitness genes. The presence of tosA was predictive of successful colonization of a murine model of infection, even among fecal isolates, and can be used as a marker of pathogenic strains of UPEC within a distinct subset of the B2 lineage

    Refining the properties of the TOI-178 system with CHEOPS and TESS

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    Context. The TOI-178 system consists of a nearby late K-dwarf transited by six planets in the super-Earth to mini-Neptune regime, with radii ranging from ~1.1 to 2.9 RāŠ• and orbital periods between 1.9 and 20.7 days. All planets but the innermost one form a chain of Laplace resonances. Mass estimates derived from a preliminary radial velocity (RV) dataset suggest that the planetary densities do not decrease in a monotonic way with the orbital distance to the star, contrary to what one would expect based on simple formation and evolution models. Aims. To improve the characterisation of this key system and prepare for future studies (in particular with JWST), we performed a detailed photometric study based on 40 new CHEOPS visits, one new TESS sector, and previously published CHEOPS, TESS, and NGTS data. Methods. First we updated the parameters of the host star using the new parallax from Gaia EDR3. We then performed a global analysis of the 100 transits contained in our data to refine the physical and orbital parameters of the six planets and study their transit timing variations (TTVs). We also used our extensive dataset to place constraints on the radii and orbital periods of potential additional transiting planets in the system. Results. Our analysis significantly refines the transit parameters of the six planets, most notably their radii, for which we now obtain relative precisions of ā‰²3%, with the exception of the smallest planet, b, for which the precision is 5.1%. Combined with the RV mass estimates, the measured TTVs allow us to constrain the eccentricities of planets c to g, which are found to be all below 0.02, as expected from stability requirements. Taken alone, the TTVs also suggest a higher mass for planet d than that estimated from the RVs, which had been found to yield a surprisingly low density for this planet. However, the masses derived from the current TTV dataset are very prior-dependent, and further observations, over a longer temporal baseline, are needed to deepen our understanding of this iconic planetary system

    Championing urban farmers in Kampala. Influences on local policy change in Uganda. Process and partnership for pro-poor policy change

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    This working paper presents an analysis of actors, events and influences affecting a policy change on urban agriculture in Kampala. It reviews the policy and institutional changes related to urban agriculture that occurred in Kampala from 1990 to 2006, and examines how and why they came about. The approach used here combined elements of three established methodologies, viz, episode studies; case study analysis; and outcome mapping. For this case study, the episode study component was central, with the case study and outcome mapping components used to cross-check and deepen the analysis. This information was assembled into three overlapping narratives: 1. A timeline of activities that played a role in changing attitudes and behaviour towards urban agriculture. 2. An analysis of the development of policies affecting urban agriculture in Kampala including the new ordinances. 3. A description of behaviour change of key actors related to the policy change These were summarised in a visual representation of the process and influences and analysed using a framework emphasising political context and the roles of evidence, linkages and external environment
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