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

Global lake responses to climate change

Climate change is one of the most severe threats to global lake ecosystems. Lake surface conditions, such as ice cover, surface temperature, evaporation and water level, respond dramatically to this threat, as observed in recent decades. In this Review, we discuss physical lake variables and their responses to climate change. Decreases in winter ice cover and increases in lake surface temperature modify lake mixing regimes and accelerate lake evaporation. Where not balanced by increased mean precipitation or inflow, higher evaporation rates will favour a decrease in lake level and surface water extent. Together with increases in extreme-precipitation events, these lake responses will impact lake ecosystems, changing water quantity and quality, food provisioning, recreational opportunities and transportation. Future research opportunities, including enhanced observation of lake variables from space (particularly for small water bodies), improved in situ lake monitoring and the development of advanced modelling techniques to predict lake processes, will improve our global understanding of lake responses to a changing climate

Mud flows in southwestern Utopia Planitia, Mars

Landforms with characteristic flow-like morphology are distributed across the southwestern portion of Utopia Planitia, Mars. Although some of the features have previously been interpreted as mud flows associated with a former presence of partly frozen muddy ocean based on their morphologies and similarities with terrestrial analogues (Ivanov et al., 2014, Icarus 228; Ivanov et al., 2015, Icarus 248), such interpretations remain ambiguous. This is because a) the evidence supporting the presence of such an ocean has been disputed by many, b) models of evolution of Utopia Planitia do not sufficiently explain the emplacement mechanisms of the flow-like landforms, and c) no in-situ measurements are available to confirm their sedimentary origin. Here we present results of a mapping exercise that focused on a field of flow-related landforms spread across a ∼ 500 × 1300 km large area centered around Adamas Labyrinthus in the attempt to provide additional insight about their formation mechanism. We mapped the distribution of 312 edifices and classified them based on their areal extent, shape, and morphological properties. We assert that these features can be grouped into four classes with distinct shapes and sizes. Their shapes are consistent with the ascent and the subsequent movement of liquid over the Martian surface. We interpret an evolutionary sequence among the classes as the differences in their morphologies can be explained by different effusion rates of the source material and the duration of the discharge at the time of their emplacement. As the result of our analysis and considering previous studies focusing on the area of our interest, we propose that all the >300 studied features were formed by subsurface sediment mobilization and that the material likely originated from the same subsurface source area. Consequently, we argue for the presence of a large body of mud within this region in the past. Finally, we note that there are several previously unconsidered sequences of events which could have resulted in such sedimentary-volcanic activity within Adamas Labyrinthus