Adult human articular chondrocytes were expanded in a medium with 10% serum (CTR) or further supplemented with different mitogens (i.e., EGF, PDGFbb, FGF-2, TGF beta 1, or FGF-2/TGF beta 1). Cells were then induced to redifferentiate in 3D pellets using serum-supplemented medium (SSM), serum-free medium (SFM), or SFM supplemented with factors inducing differentiation of chondroprogenitor cells (i.e., TGF beta 1 and/or dexamethasone). All factors tested during expansion enhanced chondrocyte proliferation and dedifferentiation, as assessed by the mRNA ratios of collagen type II to type I (CII/CI) and aggrecan to versican (Agg/Ver), using real-time PCR. FGF-2/TGF beta 1-expanded chondrocytes displayed the lowest doubling times, CII/CI and Agg/Ver ratios, averaging, respectively, 50, 0.2 and 15% of CTR-expanded cells. Redifferentiation in pellets was more efficient in SFM than SSM only for EGF-, PDGFbb- or FGF-2-expanded chondrocytes. Upon supplementation of SFM with TGF beta and dexamethasone (SFM TD), CII/CI ratios decreased 4.4-fold for EGF- and PDGFbb-expanded chondrocytes, but increased 96-fold for FGF-2/TGF beta 1-expanded cells. Chondrocytes expanded with FGF-2/TGF beta 1 and redifferentiated in SFM TD expressed the largest mRNA amounts of CII and aggrecan and generated cartilaginous tissues with the highest accumulation of glycosaminoglycans and collagen type II. Our results provide evidence that growth factors during chondrocyte expansion not only influence cell proliferation and differentiation, but also the cell potential to redifferentiate and respond to regulatory molecules upon transfer into a 3D environment.

In the first phase of the EU Emissions Trading Scheme (EU ETS), the price per ton of CO2 initially rose to over €30; the price then collapsed to essentially zero by mid 2007. By deriving a structural model of the allowance price under the assumption of efficient markets I examine the extent to which this variation in price can be explained by marginal abatement costs. I then

No abstract

No abstract

Market power in permit markets has been examined in some detail following the seminal work of Hahn (Q J Econ 99(4): [753][754][755][756][757][758][759][760][761][762][763][764][765] 1984), but the effect of free allocation on price manipulation with market power in both product and permit market has not been fully addressed. I show that in this case, the threshold of free allocation above which a dominant firm will set the permit price above its marginal abatement costs is below its optimal emissions in a competitive market, and that overall efficiency cannot be achieved by means of permit allocation alone. In addition to being of general economic interest, this issue is relevant in the context of the EU ETS. I find that the largest German, UK and Nordpool power generators received free allowances in excess of the derived threshold. Conditional on having price-setting power in both the electricity and permit markets, these firms would have found it profitable to manipulate the permit price upwards despite being net permit buyers.

No abstract

This note describes the changes in travel behaviour in response to the spread of the Sars-CoV-2 epidemic in Switzerland. The existing analyses of the Google or the national Intervisa data have limits due to missing socio-demographic details about their users. We briefly describe our GPS tracking panel and its sample. The analyses focus on the changes for different income groups and for the differences in accessibility. It will be supplemented by the weekly https://ivtmobis.ethz.ch/mobis/covid19/reports

A well-known result about market power in emission permit markets is that efficiency can be achieved by full free allocation to the dominant firm. I show that this result breaks down when taking the interaction between input and output markets into account, even if the dominant firm perceives market power in the permit market alone. I then examine the empirical evidence for price manipulation by the ten largest electricity firms during phase I of the EU ETS. I find that firms' excess allowance holdings are consistent with strategic price manipulation, and that they cannot be explained by price speculation or by precautionary purchases to insure against uncertain future emissions. My results suggest that market power is likely to be an empirically relevant concern during the early years of emission permit markets.JEL codes H23, H32; Q52, Q53, Q54, Q58.