Across a range of countries in Europe, using the Young Diagnostic Questionnaire for Internet Addiction yields a prevalence of 'pathological internet use' of 4.4% among adolescents, but varies by country and gender; adolescents lacking emotional and psychological support are at highest risk.

A list is given of all semisymmetric (edge-but not vertex-transitive) connected finite cubic graphs of order up to 768. This list was determined by the authors using Goldschmidt's classification of finite primitive amalgams of index (3, 3), and a computer algorithm for finding all normal subgroups of up to a given index in a finitely-presented group. The list includes several previously undiscovered graphs. For each graph in the list, a significant amount of information is provided, including its girth and diameter, the order of its automorphism group, the order and structure of a minimal edge-transitive group of automorphisms, its Goldschmidt type, stabiliser partitions, and other details about its quotients and covers. A summary of all known infinite families of semisymmetric cubic graphs is also given, together with explicit rules for their construction, and members of the list are identified with these. The special case of those graphs having K 1,3 as a normal quotient is investigated in detail.

Subthreshold-depression and subthreshold-anxiety are associated with an increased burden of disease and suicide risk. These results highlight the importance of early identification of adolescent subthreshold-depression and anxiety to minimize suicide. Incorporating these subthreshold disorders into a diagnosis could provide a bridge between categorical and dimensional diagnostic models.

An infinite family of vertex-and edge-transitive, but not arc-transitive, graphs of degree 4 is constructed.1991 Mathematics subject classification (Amer. Math. Soc): 05 C 25.