Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Patterns of change in beef production and consumption

Introduction The total production of beef in Africa increased from 2.8 million tonnes (t) in 1978 to 3.71 million t in 1998. This increase of 38% (1.91% per year) is higher than in the developed world where, on average, production increased by only 1%. Changes in the quantity of the beef produced are caused by the following: -changes in the total number of cattle -changes in the proportion of animals in the herd which are slaughtered -changes in the productivity of each animal. Of course, other biological, environmental and economic factors also influence these sources of change. In Africa as a whole, the total cattle population and the number of cattle slaughtered grew by about 2% per year during the years from 1978 to 1998. The largest percentage increase occurred in Central Africa. Beef yield per animal grew by less than 1% during the same period. The total consumption of beef in Africa increased faster than production. Approximately 2.6 million t of beef were consumed in 1978 and, by 1998, total consumption had grown to 3.9 million t. This rapid growth in consumption, which is equivalent to 49% (2.43% per year), is an indication of what Delgado et al. (4) refer to as the 'livestock revolution'. The growth in human population, increased urbanisation, rising income levels and, above all, changes in consumption habits explain this demand-led revolution. This paper analyses the patterns of change in the production and consumption of beef in Africa over the last two decades. A 'decomposition' method is used to analyse the percentage change in total beef production, attributable to changes in herd size, the proportion of cattle slaughtered and productivity per head of cattle. Sub-regional aggregations are complemented with similar analyses for individual countries to demonstrate the diverse patterns of change in beef production and consumption in Africa. Such an analysis should not only document elements of the 'livestock revolution', but also identify production and consumption problems that need to be addressed. Changes in herd size, percentage of slaughtered animals and yield per animal The continent of Africa contains approximately 216 million cattle. The cattle population increased by 34% (1.69% per year) Rev. sci. tech. Off. int. Epiz., 2003, 22 (3), 965-976 Summary This paper analyses the patterns of change in the production and consumption of beef in Africa over the last two decades. A 'decomposition' method of analysis is used to examine the change in total beef production during this period, attributable to changes in herd size, in the proportion of cattle slaughtered and in productivity per head of cattle. Sub-regional aggregations are complemented with similar analyses for individual countries to demonstrate the diverse patterns of change in beef production and consumption. The results reveal an overall increase in total beef production (due mainly to an increase in cattle numbers and in the percentage of slaughtered cattle, rather than to productivity gains), a stagnation in per capita production, and an overall increase in the total consumption of beef and a decline in per capita consumption (due mainly to faster population growth and urbanisation, and a decline in per capita income, respectively). Keywords Africa -Beef production and consumption -Decomposition analysis -Herd size effectInteraction effect -Off-take effect -Yield effect