300 research outputs found
Alternative interpretations of hours information in an econometric model of labour supply
This paper examines the labour supply behaviour of married women in France. Estimating a model with tax parameter variation, careful re-examination of the treatment of the unearned income variable and taking account of education in modelling preferences result in substantially lower elasticities than found in our previous empirical analysis. It turns out that distinguishing between part-time, full-time and long hours gives virtually the same results as treating observed hours as reflecting desired hours. We provide extensive specification diagnostics, including Heckman-Andrews tests, as well as Hausman tests for the comparison of different handlings of the hours information. We also consider different assumptions concerning the perception of the impact of the tax system and provide some evidence in favour of a correct perception. --
X-ray Structure of Gelatinase A Catalytic Domain Complexed with a Hydroxamate Inhibitor
Gelatinase A is a key enzyme in the family of matrix metalloproteinases (matrixins) that are involved in the degradation of the extracellular matrix. As this process is an integral part of tumour cell metastasis and angiogenesis, gelatinase is an important target for therapeutic intervention. The X-ray crystal structure of the gelatinase A catalytic domain (GaCD) complexed with batimastat (BB94), a hydroxamate inhibitor, shows an active site with a large S1\u27 specificity pocket. The structure is similar to previously solved structures of stromelysin catalytic domain (SCD) but with differences in VR1 and VR2, two surface-exposed loops on either side of the entrance to the active site. Comparison of GaCD with other members of the matrix metalloproteinase (MMP) family highlights the conservation of key secondary structural elements and the significant differences in the specificity pockets, knowledge of which should enhance our ability to design specific inhibitors for this important anticancer target
Polymer Crystallization in 25 nm Spheres
Crystallization within the discrete spheres of a block copolymer mesophase
was studied by time-resolved x-ray scattering. The cubic packing of
microdomains, established by self-assembly in the melt, is preserved throughout
crystallization by strong interblock segregation even though the amorphous
matrix block is well above its glass transition temperature. Homogeneous
nucleation within each sphere yields isothermal crystallizations which follow
first-order kinetics, contrasting with the sigmoidal kinetics normally
exhibited in the quiescent crystallization of bulk polymers.Comment: accepted for publication in Physical Review Letters, 2/28/2000;
scheduled for 5/1/2000 issu
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