Behind the Scenes with Mark von der Ruhr (Economics)

SNC Parents hear from Mark von der Ruhr, professor of Economics and SNC parent

Activation of fibrillar collagen synthesis and phenotypic modulation of chondrocytes in early human osteoarthritic cartilage lesions

SummaryThe objective of this study was to investigate the expression and extracellular distribution of fibrillar collagen types I, II, and III in early stage osteoarthritic cartilage in order to elucidate matrix gene expression and cell differentiation in early phases of the disease. Arthroscopically, derived specimens of early stage osteoarthritic articular cartilage were analyzed by histochemistry, immunohistochemistry and by in situ hybridization and compared with normal articular cartilage samples. In normal articular cartilage no significant mRNA expression of any of the investigated collagen types was found. In early stage osteoarthritic specimens, a strongly enhanced mRNA expression of the major cartilage matrix component type II collagen was detected. Additionally, a focal onset of type III, but not type I collagen expression was observed. Thus, besides activation of matrix synthesis, the modulation of the chondrocytic phenotype is likely to play a distinct role in the cellular response in the early phases of the degenerative process in osteoarthritis

Ionization wave propagation on a micro cavity plasma array

Microcavity plasma arrays of inverse pyramidal cavities have been fabricated in p-Si wafers. Each cavity acts as a microscopic dielectric barrier discharge. Operated at atmospheric pressure in argon and excited with high voltage at about 10 kHz, each cavity develops a localized microplasma. Experiments have shown a strong interaction of individual cavities, leading to the propagation of wave-like optical emission structures along the surface of the array. This phenomenon is numerically investigated using computer simulation. The observed ionization wave propagates with a speed of about 5 km/s, which agrees well the experimental findings. It is found that the wave propagation is due to sequential contributions of a drift of electrons followed by drift of ions between cavities seeded by photoemission of electrons by the plasma in adjacent cavities

Blogging Histories of Knowledge in Washington, DC

The authors reflect on their experiences as the founding editors of the History of Knowledge blog. Situating the project in its specific institutional, geographical, and historiographical contexts, they highlight its role in scholarly communication and research alongside journals and books in a research domain that is still young, especially when viewed from an international perspective. At the same time, the authors discuss the blog’s role as a tool for classifying and structuring a corpus of work as it grows over time and as new themes and connections emerge from the contributions of its many authors

The extracellular matrix proteins laminin and fibronectin modify the AMPase activity of 5'-nucleotidase from chicken gizzard smooth muscle

AbstractLaminin and fibronectin, but not collagen, affect the AMPase activity of the purified transmembrane protein 5'-nucleotidase. Laminin stimulates whereas fibronectin inhibits the AMPase activity of this ectoenzyme. The AMPase-modulating effects by these components of the extracellular matrix require a preincubation period of several hours when detergent-solubilized 5'-nucleotidase is employed, they can, however, instantaneously be elicited with liposome-incorporated 5/-nucleotidase

Robust Weak-lensing Mass Calibration of Planck Galaxy Clusters

In light of the tension in cosmological constraints reported by the Planck team between their SZ-selected cluster counts and Cosmic Microwave Background (CMB) temperature anisotropies, we compare the Planck cluster mass estimates with robust, weak-lensing mass measurements from the Weighing the Giants (WtG) project. For the 22 clusters in common between the Planck cosmology sample and WtG, we find an overall mass ratio of \left = 0.688 \pm 0.072. Extending the sample to clusters not used in the Planck cosmology analysis yields a consistent value of $\left< M_{Planck}/M_{\rm WtG} \right> = 0.698 \pm 0.062$ from 38 clusters in common. Identifying the weak-lensing masses as proxies for the true cluster mass (on average), these ratios are $\sim 1.6\sigma$ lower than the default mass bias of 0.8 assumed in the Planck cluster analysis. Adopting the WtG weak-lensing-based mass calibration would substantially reduce the tension found between the Planck cluster count cosmology results and those from CMB temperature anisotropies, thereby dispensing of the need for "new physics" such as uncomfortably large neutrino masses (in the context of the measured Planck temperature anisotropies and other data). We also find modest evidence (at 95 per cent confidence) for a mass dependence of the calibration ratio and discuss its potential origin in light of systematic uncertainties in the temperature calibration of the X-ray measurements used to calibrate the Planck cluster masses. Our results exemplify the critical role that robust absolute mass calibration plays in cluster cosmology, and the invaluable role of accurate weak-lensing mass measurements in this regard.Comment: 5 pages, 2 figure