Various known and original inequalities concerning the structure of combinatorial designs are established using polyhedral cones generated by incidence matrices. This work begins by giving definitions and elementary facts concerning t-designs. A connection with the incidence matrix W of t-subsets versus k-subsets of a finite set is mentioned. The opening chapter also discusses relevant facts ab...

Article history: Received 12 August 2009 I study the slow adoption of ring spinning in Great Britain's cotton industry at the end of the 19th century, which has been used as evidence of British entrepreneurs' declining efficiency and conservatism (Musson, 1959; Aldcroft, 1964; Lazonick, 1981, 1981b). To this purpose I use firm-level data from all of Lancashire's cotton firms over several years....

Most spider threads are on the micrometre and sub-micrometre scale. Yet, there are some spiders that spin true nano-scale fibres such as the cribellate orb spider, Uloborus plumipes. Here, we analyse the highly specialized capture silk-spinning system of this spider and compare it with the silk extrusion systems of the more standard spider dragline threads. The cribellar silk extrusion system c...