Discussion of: Statistical analysis of an archeological find

Discussion of ``Statistical analysis of an archeological find'' by Andrey Feuerverger [arXiv:0804.0079]Comment: Published in at http://dx.doi.org/10.1214/08-AOAS99F the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Firms and the global crisis: French exports in the turmoil.

The unprecedented drop in international trade during the last quarter of 2008 and the first quarter of 2009 has mostly been analysed at the macroeconomic or sectoral level. However, heterogeneous exporters in terms of productivity, size or external finance dependence should be hit differently by the crisis. This issue is examined here using data on monthly exports at the product and destination level for some 100,000 individual French exporters, up to 2009M4. We show that the drop in French exports is mainly due to the intensive margin of large exporters. Small and large firms are evenly affected when sectoral and geographical specialisations are controlled for. Lastly, firms (small and large) in sectors structurally more dependent on external finance are the most affected by the crisis.Financial crisis , international trade , firms heterogeneity , intensive and extensive margins.

A quality-by-design approach to improve process understanding and optimise the production and quality of CAR-T cells in automated stirred-tank bioreactors

Ex vivo genetically-modified cellular immunotherapies, such as chimeric antigen receptor T cell (CAR-T) therapies, have generated significant clinical and commercial outcomes due to their unparalleled response rates against relapsed and refractory blood cancers. However, the development and scalable manufacture of these novel therapies remains challenging and further process understanding and optimisation is required to improve product quality and yield. In this study, we employ a quality-by-design (QbD) approach to systematically investigate the impact of critical process parameters (CPPs) during the expansion step on the critical quality attributes (CQAs) of CAR-T cells. Utilising the design of experiments (DOE) methodology, we investigated the impact of multiple CPPs, such as number of activations, culture seeding density, seed train time, and IL-2 concentration, on CAR-T CQAs including, cell yield, viability, metabolism, immunophenotype, T cell differentiation, exhaustion and CAR expression. Initial studies undertaken in G-Rex® 24 multi-well plates demonstrated that the combination of a single activation step and a shorter, 3-day, seed train resulted in significant CAR-T yield and quality improvements, specifically a 3-fold increase in cell yield, a 30% reduction in exhaustion marker expression and more efficient metabolism when compared to a process involving 2 activation steps and a 7-day seed train. Similar findings were observed when the CPPs identified in the G-Rex® multi-well plates studies were translated to a larger-scale automated, controlled stirred-tank bioreactor (Ambr® 250 High Throughput) process. The single activation step and reduced seed train time resulted in a similar, significant improvement in CAR-T CQAs including cell yield, quality and metabolism in the Ambr® 250 High Throughput bioreactor, thereby validating the findings of the small-scale studies and resulting in significant process understanding and improvements. This study provides a methodology for the systematic investigation of CAR-T CPPs and the findings demonstrate the scope and impact of enhanced process understanding for improved CAR-T production

Firms' Export Dynamics: Experience vs. Size

This paper provides evidence about the impact that size and experience in exporting have on firms' dynamics, a critical input in models of firms' dynamics. The analysis uses a census of French exports by firm-destination-product over the period 1994-2008 with a monthly frequency. We first uncover a large calendar year bias: the growth of exporters between the first and the second year of export is biased upwards because new exporters may start exporting late during the year. This incomplete calendar year reduces export revenue by 32% on average for the first year of export. We then show that, controlling for size, export experience is negatively related to net growth of exports for surviving exporters. Controlling for export experience, the relationship between average size and net growth of exports shows no systematic pattern. Finally, churning in foreign markets is decreasing with export experience and (sharply) with size

Object-Oriented Bayesian Networks for firms' attitudes towards collusion

This paper shows how Object-Oriented Bayesian Networks can be used to model a duopolist decision process integrated with external market information. Both the relational structure and the parameters of the market behaviour model are estimated (learned) from a real dataset. Various decision scenarios are shown and discussed

Object-Oriented Bayesian Networks for firms' attitudes towards collusion

This paper shows how Object-Oriented Bayesian Networks can be used to model a duopolist decision process integrated with external market information. Both the relational structure and the parameters of the market behaviour model are estimated (learned) from a real dataset. Various decision scenarios are shown and discussed