Formal Derivation of Concurrent Garbage Collectors

Concurrent garbage collectors are notoriously difficult to implement correctly. Previous approaches to the issue of producing correct collectors have mainly been based on posit-and-prove verification or on the application of domain-specific templates and transformations. We show how to derive the upper reaches of a family of concurrent garbage collectors by refinement from a formal specification, emphasizing the application of domain-independent design theories and transformations. A key contribution is an extension to the classical lattice-theoretic fixpoint theorems to account for the dynamics of concurrent mutation and collection.Comment: 38 pages, 21 figures. The short version of this paper appeared in the Proceedings of MPC 201

Assessing the influence of land-use change on the variability of soil chemical properties in semi-arid zone of Ghana

The study aimed at providing basis to consider spatial variability in soil fertility to inform effective decision making in mineral fertilizer recommendations. The study area was classified into six land-use categories using a rural rapid appraisal technique with the aid of the farmers in the community, and by remote sensing satellite imagery (Quick bird). Land-use categories varied significantly in their nutrient, organic carbon content, and stock with coefficient of determination ranging from 0.14 to 0.46. This is reflected in decline in soil nutrient, organic carbon content, and stock with increasing number of years the land was put under cultivation except for permanently cultivated fields. Permanantly cultivated fields were located in the homestead and benefited from nutrient imports from the bush fields. The two farm types also differed significantly with respect to soil nutrients, organic carbon and stock. Soil organic carbon content was 8.2 and 4.5 g kg-1 for the homestead and bushfields, respectively. Soil organic carbon stock estimated for the two farm types were 125 and 74 t ha-1 for the homestead and bush fields, respectively. The study shows a distinct zone of nutrient enhancement within the homestead and bushfields that should be sampled separately when sampling the zone for fertilizer recommendations

Evaluation of soil properties of the Sudan Savannah ecological zone of Ghana for crop production

Low soil fertility and limited ability of farmers to purchase fertilizers in the Sudan savannah zone of Ghana has resulted in the decline in the yield of cereals over the years. There is, therefore, the need to identify soil parameters that are critical to crop production, to manage them effectively and improve fertilizer use efficiency to increase crop yield. To achieve this, an area of about 1.5 km2 was divided into grid cells (100m2) and characterised for their soil properties (organic carbon, pH, and soil texture). Data collected was used in a pedo-transfer function to estimate additional soil parameters that were not measured (i.e. wilting point, field capacity, available water and saturation). These were used as input to the crop simulation model (APSIM- Agriculture Productions Systems sIMulator) to simulate sorghum grain yield for each grid cell. Linear regression and factor analysis were also employed in explaining the data. Grain yield ranged from 402 to 1092 kg ha-1 with a mean of 673 kg ha-1 using 2005 weather data and 228 to 907 kg ha-1 with a mean of 427 kg ha-1 using 2000 weather data without fertilizer application. The model was sensitive to all input parameters. Soil texture and organic carbon were identified to have significant effect on crop yield. Soil organic carbon is, therefore, to be managed for the development of a good tilth and hence sustainable yields of sorghum at the study site

Mode of Biochar Application to Vertisols Influences Water Balance Components and Water Use Efficiency of Maize (Zea mays L.)

Vertisols belong to a group of soils with high fertility but poor physical properties of swelling when wet and shrinking and cracking when dry. The swelling inhibits infiltration, resulting in flooding, limiting the production of upland crops. Biochar (<BC) application has been shown to reduce the shrink-swell behaviour of Vertisols. However, the mode of biochar application to these soils may affect the effectiveness of the amendment. This study investigated the water relations and maize (Zea mays L.) growth under two BC application modes: (i) biochar applied into cracks that develop with drying, C, and (ii) biochar that was surface broadcast and incorporated into the topsoil, FM. A control treatment did not receive any BC amendment. Maize was grown on the BC-amended Vertisols using the two modes of application in a greenhouse under two seasonal water regimes of 610 and 450 mm. The results showed that the proportion of total water application lost to runoff was 37%, 49% and 53% for C, FM and control treatments, respectively. Both maize yield and Water Use Efficiency (WUE), for the C treatments were significantly (p < 0.05) higher than those for FM treatments. The maize yield under the C treatments was 19% over the control. Similarly, the WUE for the C treatments was 28% above the control treatment. It is concluded that the application of biochar into cracks is a more effective way of improving the water relations and upland crop productivity and WUE in Vertisols than the traditional surface incorporation

The polycystic kidney disease 1 gene encodes a 14 kb transcript and lies within a duplicated region on chromosome 16

Autosomal dominant polycystic kidney disease (ADPKD) is a common genetic disorder that frequently results in renal fallure due to progressive cyst development. The major locus, PKD1, maps to 16p13.3. We identified a chromosome translocation associated with ADPKD that disrupts a gene (PBP) encoding a 14 kb transcript in the PKD1 candidate region. Further mutations of the PBP gene were found in PKD1 patients, two deletions (one a de novo event) and a splicing defect, confirming that PBP is the PKD1 gene. This gene is located adjacent to the TSC2 locus in a genomic region that is reiterated more proximally on 16p. The duplicate area encodes three transcripts substantially homologous to the PKD1 transcript. Partial sequence analysis of the PKD1 transcript shows that it encodes a novel protein whose function is at present unknown

How are gender equality and human rights interventions included in sexual and reproductive health programmes and policies: A systematic review of existing research foci and gaps

The importance of promoting gender equality and human rights in sexual and reproductive health (SRH) programmes and policies has been affirmed in numerous international and regional agreements, most recently the 2030 Agenda for Sustainable Development. Given the critical role of research to determine what works, we aimed to identify research gaps as part of a broader priority setting exercise on integrating gender equality and human rights approaches in SRH programmes and policies. A systematic literature review of reviews was conducted to examine the question: what do we know about how research in the context of SRH programmes and policies has addressed gender equality and human rights and what are the current gaps in research. We searched three databases for reviews that addressed the research question, were published between 1994-2014, and met methodological standards for systematic reviews, qualitative meta-syntheses and other reviews of relevance to the research question. Additional grey literature was identified based on expert input. Articles were appraised by the primary author and examined by an expert panel. An abstraction and thematic analysis process was used to synthesize findings. Of the 3,073 abstracts identified, 56 articles were reviewed in full and 23 were included along with 10 from the grey literature. The majority focused on interventions addressing gender inequalities; very few reviews explicitly included human rights based interventions. Across both topics, weak study designs and use of intermediate outcome measures limited evidence quality. Further, there was limited evidence on interventions that addressed marginalized groups. Better quality studies, longer-term indicators, and measurement of unintended consequences are needed to better understand the impact of these types of interventions on SRH outcomes. Further efforts are needed to cover research on gender equality and human rights issues as they pertain to a broader set of SRH topics and populations.Scopu

Location and Land use effects on Soil Carbon Accretion and Productivity in the Coastal Savanna Agro-ecological Zone of Ghana

Land use type, climate and soil properties are major determinants of soil carbon storage and productivity, especially in low-input agriculture. In this study, we investigated the interactions among these factors at four (4) locations, namely Accra Metropolis, Ga West, Ga East and Shai Osudoku, within the Coastal-Savannah agro-ecological zone of Ghana. The land use types were maize-based cropping, cassava-based cropping, woodlot/plantations and natural forests. The impact of these on soil productivity at a given location was assessed in terms of soil carbon stocks and a Soil Productivity Index (SPI). The SPI is a composite value derived from routine soil properties such as: soil texture, available water capacity, pH, cation exchange capacity, soil organic carbon, available P, exchangeable K, potentially mineralizable nitrogen, and basic cations, among others. Principal component analysis was used to select soil properties that were used to estimate SPI. The results showed that the locations differed with respect to rainfall regimes and soil types. Locations with slightly heavier soil texture and relatively higher rainfall regimes (Ga East and Shai Osudoku) had significantly higher soil carbon storage and SPI values than the lighter soil textured locations (Accra Metropolis and Ga West). With regards to land use, forest had significantly higher soil carbon storage and SPI than all the other land use types, irrespective of location. The order of soil carbon storage and SPI were: forest > woodlot/plantation > cassava > maize. It was observed that though the Accra Metropolis location hosted the oldest forest, soil carbon was still low, apparently due to the lighter soil texture. We concluded that the soil productivity restorative ability is an interactive effect of carbon management (land use), soil texture and other properties. This interaction hitherto has not been adequately investigated, especially in low-input agriculture

Productivity of Soybean under Projected Climate Change in a Semi-Arid Region of West Africa: Sensitivity of Current Production System

The production of soybean is gaining more attention in West Africa. In light of projected changes in climate, there is a need to assess the potential impacts on yield productivity and variability among farmers. An evaluated GROPGRO module of the Decision Support System for Agro-technological Transfer (DSSAT) was used to simulate soybean productivity under both historical (1980–2009) and projected climate scenarios from multiple general circulation models (GCMs) under two representative concentration pathways (RCPs): 4.5 and 8.5. Agronomic data from 90 farms, as well as multiple soil profile data, were also used for the impact assessment. Climate change leads to a reduction (3% to 13.5% across GCMs and RCPs) in the productivity of soybean in Northern Ghana. However, elevated atmospheric carbon dioxide has the potential to offset the negative impact, resulting in increased (14.8% to 31.3% across GCMs and RCPs) productivity. The impact of climate change on yield varied widely amongst farms (with relative standard deviation (RSD) ranging between 17% and 35%) and across years (RSD of between 10% and 15%). Diversity in management practices, as well as differences in soils, explained the heterogeneity in impact among farms. Variability among farms was higher than that among years. The strategic management of cultural practices provides an option to enhance the resilience of soybean productivity among smallholder

Patterns of ash (Fraxinus excelsior L.) colonization in mountain grasslands: the importance of management practices

International audienceWoody colonization of grasslands is often associated with changes in abiotic or biotic conditions or a combination of both. Widely used as fodder and litter in the past traditional agro-pastoral system, ash (Fraxinus excelsior L.) has now become a colonizing species of mountain grasslands in the French Pyrenees. Its present distribution is dependent on past human activities and it is locally controlled by propagule pressure and abiotic conditions. However, even when all favourable conditions are met, all the potentially colonizable grasslands are not invaded. We hypothesize that management practices should play a crucial role in the control of ash colonization. From empirical field surveys we have compared the botanical composition of a set of grasslands (present and former) differing in management practices and level of ash colonization. We have displayed a kind of successional gradient positively linked to both ash cover and height but not to the age of trees. We have tested the relationships between ash presence in grassland and management types i.e. cutting and/or grazing, management intensity and some grassland communities' features i.e. total and local specific richness and species heterogeneity. Mixed use (cutting and grazing) is negatively linked to ash presence in grassland whereas grazing alone positively. Mixed use and high grazing intensity are directly preventing ash seedlings establishment, when low grazing intensity is allowing ash seedlings establishment indirectly through herbaceous vegetation neglected by livestock. Our results show the existence of a limit between grasslands with and without established ashes corresponding to a threshold in the intensity of use. Under this threshold, when ash is established, the colonization process seems to become irreversible. Ash possesses the ability of compensatory growth and therefore under a high grazing intensity develops a subterranean vegetative reproduction. However the question remains at which stage of seedling development and grazing intensity these strategies could occur

The Mantle Transition Zone Beneath West Antarctica: Seismic Evidence for Hydration and Thermal Upwellings

Although prior work suggests that a mantle plume is associated with Cenozoic rifting and volcanism in West Antarctica, the existence of a plume remains conjectural. Here we use P wave receiver functions (PRFs) from the Antarctic POLENET array to estimate mantle transition zone thickness, which is sensitive to temperature perturbations, throughout previously unstudied parts of West Antarctica. We obtain over 8000 high-quality PRFs using an iterative, time domain deconvolution method filtered with a Gaussian width of 0.5 and 1.0, corresponding to frequencies less than ∼0.24 and ∼0.48 Hz, respectively. Single-station and common conversion point stacks, migrated to depth using the AK135 velocity model, indicate that mantle transition zone thickness throughout most of West Antarctica does not differ significantly from the global average, except in two locations; one small region exhibits a vertically thinned (210 ± 15 km) transition zone beneath the Ruppert Coast of Marie Byrd Land and another laterally broader region shows slight, vertical thinning (225 ± 25 km) beneath the Bentley Subglacial Trench. We also observe the 520 discontinuity and a prominent negative peak above the mantle transition zone throughout much of West Antarctica. These results suggest that the mantle transition zone may be hotter than average in two places, possibly due to upwelling from the lower mantle, but not broadly across West Antarctica. Furthermore, we propose that the transition zone may be hydrated due to \u3e100 million years of subduction beneath the region during the early Mesozoic