Noncommutative Lattices and Their Continuum Limits

We consider finite approximations of a topological space $M$ by noncommutative lattices of points. These lattices are structure spaces of noncommutative $C^*$-algebras which in turn approximate the algebra \cc(M) of continuous functions on $M$. We show how to recover the space $M$ and the algebra \cc(M) from a projective system of noncommutative lattices and an inductive system of noncommutative $C^*$-algebras, respectively.Comment: 22 pages, 8 Figures included in the LaTeX Source New version, minor modifications (typos corrected) and a correction in the list of author

Epistemic policy networks in the European Union’s CBRN risk mitigation policy

This paper offers insights into an innovative and currently flagship approach of the European Union (EU) to the mitigation of chemical, biological, radiological, and nuclear (CBRN) risks. Building on its long-time experience in the CBRN field, the EU has incorporated methods familiar to the students of international security governance: it is establishing regional networks of experts and expertise. CBRN Centers of Excellence, as they are officially called, aim to contribute to the security and safety culture in different parts of Africa, the Middle East, South East Asia, and South East Europe, in the broadly construed CBRN area. These regional networks represent a modern form of security cooperation, which can be conceptualized as an epistemic policy networks approach. It offers flexibility to the participating states, which have different incentives to get involved. At the same, however, the paper identifies potential limitations and challenges of epistemic policy networks in this form

Dewetting of thin polymer films near the glass transition

Dewetting of ultra-thin polymer films near the glass transition exhibits unexpected front morphologies [G. Reiter, Phys. Rev. Lett., 87, 186101 (2001)]. We present here the first theoretical attempt to understand these features, focusing on the shear-thinning behaviour of these films. We analyse the profile of the dewetting film, and characterize the time evolution of the dry region radius, $R_{d}(t)$, and of the rim height, $h_{m}(t)$. After a transient time depending on the initial thickness, $h_{m}(t)$ grows like $\sqrt{t}$ while $R_{d}(t)$ increases like $\exp{(\sqrt{t})}$. Different regimes of growth are expected, depending on the initial film thickness and experimental time range.Comment: 4 pages, 5 figures Revised version, published in Physical Review Letters: F. Saulnier, E. Raphael and P.-G. de Gennes, Phys. Rev. Lett. 88, 196101 (2002

Characterization of early ultrastructural changes in the cerebral white matter of CADASIL small vessel disease using high pressure freezing/freeze-substitution

AIMS: The objective of this study was to elucidate the early white matter changes in CADASIL small vessel disease. METHODS: We used high pressure freezing and freeze substitution (HPF/FS) in combination with high resolution electron microscopy (EM), immunohistochemistry and confocal microscopy of brain specimens from control and CADASIL (TgNotch3R169C ) mice aged 4 to 15 months to study white matter lesions in the corpus callosum. RESULTS: We first optimized the HPF/FS protocol in which samples were chemically prefixed, frozen in a sample carrier filled with 20% polyvinylpyrrolidone and freeze-substituted in a cocktail of tannic acid, osmium tetroxide and uranyl acetate dissolved in acetone. EM analysis showed that CADASIL mice exhibit significant splitting of myelin layers and enlargement of the inner tongue of small calibre axons from the age of 6 months, then vesiculation of the inner tongue and myelin sheath thinning at 15 months of age. Immunohistochemistry revealed an increased number of oligodendrocyte precursor cells, although only in older mice, but no reduction in the number of mature oligodendrocytes at any age. The number of Iba1 positive microglial cells was increased in older but not in younger CADASIL mice, but the number of activated microglial cells (Iba1 and CD68 positive) was unchanged at any age. CONCLUSION: We conclude that early WM lesions in CADASIL affect first and foremost the myelin sheath and the inner tongue, suggestive of a primary myelin injury. We propose that those defects are consistent with a hypoxic/ischaemic mechanism

Study of the pitch change of carbon coils during their growth

AbstractIn the present paper, carbon coils (CCs) were prepared by CVD. Their morphology, particularly pitch changes of the carbon coils prepared in different conditions were observed. It was found that the carbon source flow plays an important role in carbon coil growth and its morphology evolution. The appropriate atmosphere and flow rate is beneficial to the steady reactivity of catalyst particles. As such each carbon coil can grow well and have an exact growth rate. When the carbon supply is sufficient, the CCs exhibit close spiral and small coil diameter. When carbon supply decreases, small carbon supply leads to large pitch and coil diameter. CCs can be synthesized with different coil pitch under different carbon supply. This may be of great significance for the controllable preparation of carbon coil and its application