1,720,963 research outputs found
Climate change in Malawi: Household level impacts and adaptations
No full textUsing three waves of national representative household level panel data from Malawi, we estimate a structural model to study how households make production decisions in response to climate change. In doing so, we examine two forms of adaptation: 1) adopting improved maize varieties and 2) adjusting input and output quantities. Our results indicate that climate change induces both forms of adaptation, though only the second appears relevant in determining climate change impacts. Accounting for these expected adjustments in input and output mix, we estimate that net household income increases 0.86% for a 1% increase in the historical variability of total growing season precipitation, while income decreases by 2.09% for every 1% increase in the historical variability of monthly precipitation within the growing season. The impacts associated with higher rainfall variability are more favorable for households with greater levels of asset ownership. Specifically, we observe that the extent to which households diversify income sources in response to intra-seasonal rainfall variability depends on asset ownership, suggesting that assets enhance a household\u27s capacity for adaptation to climate change
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Rural land rental markets and agricultural development in Africa
No full textRecent scholarship has shown that land rental and sales markets are increasingly important within
customary tenure systems in Africa (e.g. Holden et al. 2009). The theoretical role of such markets in
enhancing equitable access and production efficiency is of particular relevance for Africa’s agrarian
economies, which are characterized by highly skewed distributions of land access (even within
smallholder sector), low levels of productivity and high levels of poverty. Empirical assessments of land
market performance have generally not found conclusive evidence of their impacts on the smallholder
farm sector. This session will review several important recent empirical assessments of rural land rental
markets in Eastern and Southern Africa, focusing on case studies in Kenya, Malawi and Zambia, and
West Africa, in Côte d’Ivoire. We will attempt to synthesize what we know about the current status of
rental market development in the region, focusing on addressing several key questions: What are the
temporal and spatial trends of rental market development? Who is participating in these markets? What
are the impacts on smallholder efficiency, equity and household welfare? In addition to summarizing the
available evidence, we will attempt to clarify the most appropriate ways for agricultural policy to engage
with land market development and will highlight areas requiring further research
Nutrient management in African sorghum cropping systems: applying meta-analysis to assess yield and profitability
No full textInternational audienceAbstractDeclining soil fertility and limited farmer access to inorganic fertilizer frequently cause sub-optimal grain yields throughout sub-Saharan Africa. Farm productivity is also at risk from extreme weather and future climate change. Significant uncertainty remains in predicting climate in Africa, increasing the challenge of planning for climate change adaptation. Sorghum is adapted to African climate patterns and is predicted to maintain widespread suitability across different African climatic zones under climate change. Sorghum’s drought tolerance and ability to withstand water logging make it an important crop for maintaining productive agroecosystems under a changing climate. Due to its status as a staple grain, improved sorghum management can provide smallholder farmers with stability in their household nutritional needs. We reviewed sorghum (Sorghum bicolor) yield trends across nutrient management scenarios using meta-analysis. We compared yield across eight nutrient management practices: (i) N-only, (ii) P-only, (iii) N and P, (iv) N and P microdose, (v) legume management, (vi) manure addition, (vii) organic matter (OM) amendment, and (viii) mixed amendment. Our review demonstrated (1) yield improvement considering all scenarios averaged 66 % relative to no nutrient inputs, (2) yield under chemical fertilizer amendment increased by 47–98 % of control yield, (3) yield under organic nutrient amendment increased by 43–87 % of control yield, and (4) the profitability of a management scenario was not solely determined by the magnitude of yield increase. For example, due to the high cost of fertilizer, addition of nitrogen (N) and phosphorus (P) generated the largest yield increase, but the lowest profit, in two of three countries analyzed. In contrast, an edible legume in rotation averaged 43 % yield improvement relative to no nutrient inputs and a net profit of US 263 per hectare. Facilitating access to both fertilizer inputs and diversified rotations has the greatest potential to increase grain yield in Africa
What are the Drivers of Rural Land Rental Markets in sub-Saharan Africa, and how do they Impact Household Welfare? Evidence from Malawi and Zambia
No full textThis article uses nationally representative panel survey data from Malawi and Zambia to estimate the factors affecting a smallholder farm household’s decision to participate in land rental markets as either a tenant or a landlord. We also estimate how land rental market participation influences various measures of household income and welfare. We find that land rental markets in both Malawi and Zambia promote efficiency by transferring land from less able to more able farmers. Land rental markets in Malawi promote equity by transferring land relatively labor-poor to labor-rich households, and in both countries we find evidence that land markets transfer land from land-rich to land-poor households. In both countries, we find evidence that renting in land has a positive effect on household income and reduces the probability of the household being in poverty. However, when we consider the full cost of renting in land, the positive impacts are much lower
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