A linear diforest is a digraph whose connected components are paths. We define the linear arboricity of a digraph, denoted lii(G), as the minimum number of linear diforests which partition the arcs of G. In this paper, we prove that the determination of G(G) is NP-complete. We prove also that the problem becomes polynomial for acyclic digraphs. Finally, we give the value of lii(G) for several families of digraphs, in particular 2-regular digraphs.

A facile photogeneration of a stable radical species from a 4-substituted pyridine derivative under ambient conditions is achieved. The radical generation reaction accompanies visible colour change into green and is repeatable multiple times.

Our aim was to determine differences in thermal comfort during simulated one-day parcel home delivery between summer and winter. Six young healthy males performed experiments in summer (up to 31°C) and winter (up to 8°C). After baseline measurement in a chamber, subjects drove a truck to a prespecified location for outside measurements. They performed 4 sets of 100-m walk with carrying 5-kg plate during the first 50-m walk at 100 m/min, separated by 7-min driving in each of the morning and the afternoon. Subjects could ingest water ad libitum in outside and set the cockpit temperature by themselves during driving. Thermal sensation and comfort were recorded using a subjective scale at the first and the last sets of each morning and afternoon session, while esophageal temperature (Tes) was monitored (thermocouples). Body weight was measured before and the end of experiment. We found that 1) whole-body comfort decreased in summer and the decrease was greater than winter with higher Tes and 2) changes in body weight were 0.7 and 0.3 kg through whole day in summer and winter, respectively. In summary, thermal comfort during working worsened in summer, possibly related with higher core temperature and greater decrease in body weight.

No abstract