We argue that system-level international changes have made secessionism more attractive since 1945, and that this is one of the reasons for the recent proliferation of aspiring states. Using original data on secessionist movements between 1816 and 2011, we document that secessionism became significantly more common after 1945. Whereas much of the existing literature explains secessionism by pointing to local or unitlevel factors, we contend that security, economic, and normative changes at the international level have effectively increased the benefits of independence, without a commensurate increase in the costs. We use interviews with representatives of new states, secessionist groups, and international organizations to provide empirical support for these claims. We conclude by considering three extensions of our argument: (i) Does the nature of the changing international environment affect the way in which secessionists attempt to achieve their goals? (ii) What future changes might amplify or depress this trend? (iii) Who are the specific people benefiting from statehood, and can their position within a would-be state help us understand the nature of secessionism today? 1 Authors' notes: For valuable comments and suggestions, we thank

Common wisdom and current scholarship hold that governments need to stand firm in the face of secessionist demands, since permitting the secession of one region can set a precedent for others. For this reason governments will often choose blood rather than risk dissolution. I argue that administrative organization provides states with a third option. Those regions that represent a unique administrative type stand a much better chance of seceding peacefully. Moreover, large articulated states sometimes downsize by administrative category, which helps explain why governments will release one set of units without contest while preventing another set from doing the same. Finally, secessionist movements that do not cohere with any administrative region are the least likely to be granted independence. In sum, the administrative architecture of states provides governments with a means to discriminate between secessionist demands. I test this theory in a large-N study using original data on secessionist movements and administrative units between 1816 and 2011.

We propose a game theoretical model to assess the capacity of Catalonia to become a recognized, independent country with at least a de facto European Union (EU) membership. Support for Catalan independence is increasing for reasons pertaining to identity and economics. Spain can avoid a vote for independence by effectively 'buying-out' a proportion of the Catalan electorate with a funding agreement favorable to Catalonia. If, given the current economic circumstances, the buying-out strategy is too expensive, a proindependence vote is likely to pass. Our model predicts an agreement in which Spain and the European Union accommodate Catalan independence in exchange for Catalonia taking a share of the Spanish debt. If Spain and the EU do not accommodate, Spain becomes insolvent, which in turn destabilizes the EU. The current economic woes of Spain and the EU both contribute to the desire for Catalan independence and make it possible.

The human gut symbiont Ruminococcus gnavus displays strain-specific repertoires of glycoside hydrolases (GHs) contributing to its spatial location in the gut. Sequence similarity network analysis identified strain-specific differences in blood-group endo-β-1,4-galactosidase belonging to the GH98 family. We determined the substrate and linkage specificities of GH98 from R. gnavus ATCC 29149, RgGH98, against a range of defined oligosaccharides and glycoconjugates including mucin. We showed by HPAEC-PAD and LC-FD-MS/MS that RgGH98 is specific for blood group A tetrasaccharide type II (BgA II). Isothermal titration calorimetry (ITC) and saturation transfer difference (STD) NMR confirmed RgGH98 affinity for blood group A over blood group B and H antigens. The molecular basis of RgGH98 strict specificity was further investigated using a combination of glycan microarrays, site-directed mutagenesis, and X-ray crystallography. The crystal structures of RgGH98 in complex with BgA trisaccharide (BgAtri) and of RgGH98 E411A with BgA II revealed a dedicated hydrogen network of residues, which were shown by site-directed mutagenesis to be critical to the recognition of the BgA epitope. We demonstrated experimentally that RgGH98 is part of an operon of 10 genes that is overexpresssed in vitro when R. gnavus ATCC 29149 is grown on mucin as sole carbon source as shown by RNAseq analysis and RT-qPCR confirmed RgGH98 expression on BgA II growth. Using MALDI-ToF MS, we showed that RgGH98 releases BgAtri from mucin and that pretreatment of mucin with RgGH98 confered R. gnavus E1 the ability to grow, by enabling the E1 strain to metabolise BgAtri and access the underlying mucin glycan chain. These data further support that the GH repertoire of R. gnavus strains enable them to colonise different nutritional niches in the human gut and has potential applications in diagnostic and therapeutics against infection.