Université catholique de Louvain

About: Université catholique de Louvain is a education organization based out in Louvain-la-Neuve, Belgium. It is known for research contribution in the topics: Population & Catalysis. The organization has 25319 authors who have published 57360 publications receiving 2172080 citations. The organization is also known as: University of Louvain & UCLouvain.

Expressive key-policy attribute-based encryption with constant-size ciphertexts

Abstract: Attribute-based encryption (ABE), as introduced by Sahai and Waters, allows for fine-grained access control on encrypted data. In its key-policy flavor, the primitive enables senders to encrypt messages under a set of attributes and private keys are associated with access structures that specify which ciphertexts the key holder will be allowed to decrypt. In most ABE systems, the ciphertext size grows linearly with the number of ciphertext attributes and the only known exceptions only support restricted forms of threshold access policies. This paper proposes the first key-policy attribute-based encryption (KP-ABE) schemes allowing for non-monotonic access structures (i.e., that may contain negated attributes) and with constant ciphertext size. Towards achieving this goal, we first show that a certain class of identity-based broadcast encryption schemes generically yields monotonic KPABE systems in the selective set model. We then describe a new efficient identity-based revocation mechanism that, when combined with a particular instantiation of our general monotonic construction, gives rise to the first truly expressive KP-ABE realization with constant-size ciphertexts. The downside of these new constructions is that private keys have quadratic size in the number of attributes. On the other hand, they reduce the number of pairing evaluations to a constant, which appears to be a unique feature among expressive KP-ABE schemes.

Land management and land-cover change have impacts of similar magnitude on surface temperature

Abstract: The direct effects of land-cover change on surface climate are increasingly well understood, but fewer studies have investigated the consequences of the trend towards more intensive land management practices. Now, research investigating the biophysical effects of temperate land-management changes reveals a net warming effect of similar magnitude to that driven by changing land cover. Anthropogenic changes to land cover (LCC) remain common, but continuing land scarcity promotes the widespread intensification of land management changes (LMC) to better satisfy societal demand for food, fibre, fuel and shelter1. The biophysical effects of LCC on surface climate are largely understood2,3,4,5, particularly for the boreal6 and tropical zones7, but fewer studies have investigated the biophysical consequences of LMC; that is, anthropogenic modification without a change in land cover type. Harmonized analysis of ground measurements and remote sensing observations of both LCC and LMC revealed that, in the temperate zone, potential surface cooling from increased albedo is typically offset by warming from decreased sensible heat fluxes, with the net effect being a warming of the surface. Temperature changes from LMC and LCC were of the same magnitude, and averaged 2 K at the vegetation surface and were estimated at 1.7 K in the planetary boundary layer. Given the spatial extent of land management (42–58% of the land surface) this calls for increasing the efforts to integrate land management in Earth System Science to better take into account the human impact on the climate8.

Mutations in the transcription factor gene SOX18 underlie recessive and dominant forms of hypotrichosis-lymphedema-telangiectasia.

Abstract: Hereditary lymphedema is a developmental disorder characterized by chronic swelling of the extremities due to dysfunction of the lymphatic vessels. Two responsible genes have been identified: the vascular endothelial growth factor receptor 3 (VEGFR3) gene, implicated in congenital lymphedema, or Milroy disease, and the forkhead-related transcription factor gene FOXC2, causing lymphedema-distichiasis. We describe three families with an unusual association of hypotrichosis, lymphedema, and telangiectasia. Using microsatellite analysis, we first excluded both VEGFR3 and FOXC2 as causative genes; we then considered the murine ragged phenotype, caused by mutations in the Sox18 transcription factor, as a likely counterpart to the human disease, because it presents a combination of hair and cardiovascular anomalies, including symptoms of lymphatic dysfunction. Two of the families were consanguineous; in affected members of these families, we identified homozygous missense mutations in the SOX18 gene, located in 20q13. The two amino acid substitutions, W95R and A104P, affect conserved residues in the first α helix of the DNA-binding domain of the transcription factor. In the third family, the parents were nonconsanguineous, and both the affected child and his brother, who died in utero with hydrops fetalis, showed a heterozygous nonsense mutation that truncates the SOX18 protein in its transactivation domain; this substitution was not found in genomic DNA from either parent and hence constitutes a de novo germline mutation. Thus, we show that SOX18 mutations in humans cause both recessive and dominant hypotrichosis-lymphedema-telangiectasia, suggesting that, in addition to its established role in hair and blood vessel development, the SOX18 transcription factor plays a role in the development and/or maintenance of lymphatic vessels.