Old World megadroughts and pluvials during the Common Era

Climate model projections suggestwidespread drying in the Mediterranean Basin and wetting in Fennoscandia in the coming decades largely as a consequence of greenhouse gas forcing of climate. To place these and other “Old World” climate projections into historical perspective based on more complete estimates of natural hydroclimatic variability, we have developed the “Old World Drought Atlas” (OWDA), a set of year-to-year maps of tree-ring reconstructed summer wetness and dryness over Europe and the Mediterranean Basin during the Common Era.
The OWDA matches historical accounts of severe drought and wetness with a spatial completeness not previously available. In addition, megadroughts reconstructed over north-central Europe in the 11th and mid-15th centuries
reinforce other evidence from North America and Asia that droughts were more severe, extensive, and prolonged over Northern Hemisphere land areas before the 20th century, with an inadequate understanding of their causes. The OWDA provides new data to determine the causes of Old World drought and wetness and attribute past climate variability to forced and/or internal variability.

Efficient RkNN Retrieval with Arbitrary Non-Metric Similarity Measures

A RkNN query returns all objects whose nearest k neighbors
contain the query object. In this paper, we consider RkNN
query processing in the case where the distances between
attribute values are not necessarily metric. Dissimilarities
between objects could then be a monotonic aggregate of dissimilarities
between their values, such aggregation functions
being specified at query time. We outline real world cases
that motivate RkNN processing in such scenarios. We consider
the AL-Tree index and its applicability in RkNN query
processing. We develop an approach that exploits the group
level reasoning enabled by the AL-Tree in RkNN processing.
We evaluate our approach against a Naive approach
that performs sequential scans on contiguous data and an
improved block-based approach that we provide. We use
real-world datasets and synthetic data with varying characteristics
for our experiments. This extensive empirical
evaluation shows that our approach is better than existing
methods in terms of computational and disk access costs,
leading to significantly better response times.

Clustering-Based Ensemble Method as an Alternative to Stacking

One of the most popular techniques of generating classifier ensembles is known as stacking which is based on a meta-learning approach. In this paper, we introduce an alternative method to stacking which is based on cluster analysis. Similar to stacking, instances from a validation set are initially classified by all base classifiers. The output of each classifier is subsequently considered as a new attribute of the instance. Following this, a validation set is divided into clusters according to the new attributes and a small subset of the original attributes of the instances. For each cluster, we find its centroid and calculate its class label. The collection of centroids is considered as a meta-classifier. Experimental results show that the new method outperformed all benchmark methods, namely Majority Voting, Stacking J48, Stacking LR, AdaBoost J48, and Random Forest, in 12 out of 22 data sets. The proposed method has two advantageous properties: it is very robust to relatively small training sets and it can be applied in semi-supervised learning problems. We provide a theoretical investigation regarding the proposed method. This demonstrates that for the method to be successful, the base classifiers applied in the ensemble should have greater than 50% accuracy levels.

A biological survey method applied to seafloor massive sulphides (SMS) with contagiously distributed hydrothermal-vent fauna

Strategies for mitigation of seafloor massive sulphide (SMS) extraction in the deep sea include establishment of suitable reference sites that allow for studies of natural environmental variability and that can serve as sources of larvae for re-colonisation of extracted hydrothermal fields. In this study, we characterize deep-sea vent communities in Manus Basin (Bismarck Sea, Papua New Guinea) and use macrofaunal data sets from a proposed reference site (South Su) and a proposed mine site (Solwara 1) to test the hypothesis that there was no difference in macrofaunal community structure between the sites. We used dispersion weighting to adjust taxa-abundance matrices to down-weight the contribution of contagious distributions of numerically abundant taxa. Faunal assemblages of 3 habitat types defined by biogenic taxa (2 provannid snails, Alviniconcha spp. and Ifremeria nautilei; and a sessile barnacle, Eochionelasmus ohtai) were distinct from one another and from the vent peripheral assemblage, but were not differentiable from mound-to-mound within a site or between sites. Mussel and tubeworm populations at South Su but not at Solwara 1 enhance the taxonomic and habitat diversity of the proposed reference site. © Inter-Research 2012.

‘Harmonising the precaution out of the precautionary principle? The need for maintaining flexibility and an interpretative role’

The precautionary principle has the potential to act as a valuable tool in food law. It operates in areas of scientific uncertainty, calling for protective measures where there are potential threats to human health (or the environment). However, the manner of the principle’s incorporation and implementation within legislation are key to its effectiveness and general legitimacy. Specific considerations include the role and nature of risk assessments, assessors, sources of evidence, divergent opinions, risk communication, other legitimate factors and the weighting of interests. However, more fundamentally, the crystallisation of approaches and removal of all flexibility would undermine the principle’s central tenets. Firstly, principles crucially play a guiding and interpretative role. Secondly, reflexive modernisation and continuing scientific uncertainty call for the precautionary principle’s continued application – precautionary measures do not end the precautionary principle’s relevance. This can be partially achieved through the legislation so as to facilitate later precautionary measures, e.g. through temporary authorisations, derogations and safeguard clauses. However, crucially, it requires that the legislation also be interpreted in light of the precautionary principle. This paper investigates the logic behind the Court of Justice of the EU’s judgments and the circumstances that enable or deter the Court in taking, or permitting, stronger precautionary approaches. Although apparently inconsistent, a number of contextual factors including the legislative provisions and actors involved influence the judgments substantially. The analysis provides insight into improving the principle’s incorporation to facilitate its continued application and maintenance of flexibility, whilst bearing in mind the general desirability of objectivity and legal certainty.