Information on cerebral oxygenation during prolonged driving in healthy humans may help to explain the cause and development of central fatigue and its effects on cortex activities. The objective of this study is to investigate the time course of cerebral oxygenation during a prolonged driving task. Forty healthy male subjects were randomly divided into two groups: task group (Task) and control group (CNL). All subjects were required to rest well prior to the experiment. For the task group, subjects were required to perform the simulated driving task for 3 h. Cerebral oxygenation signal was monitored from the left frontal lobe using near infrared spectroscopy throughout the entire experiment. Significant increases in the concentrations of HbO(2) (DeltaCHbO(2)) and HbT (DeltaCHbT) were recorded at the start of driving task compared with the resting value (p < 0.01). The cerebral oxygen saturation in the Task group was found to be significantly lower following three hours of driving compared with that in the CNL (F = 16.95, p < 0.001). In addition, a significant difference in selective reaction time was observed between the Task group and CNL during the post-task period (p = 0.023). The results demonstrated that the cerebral oxygenation is closely related to the mental stress. The decrease in the cerebral oxygen saturation may indicate reduced cerebral oxygen delivery, and this may be an important factor affecting central fatigue development during prolonged driving.

DP-coloring (also known as correspondence coloring) of a simple graph is a generalization of list coloring. It is known that planar graphs without 4-cycles adjacent to triangles are 4-choosable, and planar graphs without 4-cycles are DP-4-colorable. In this paper, we show that planar graphs without 4-cycles adjacent to triangles are DP-4-colorable, which is an extension of the two results above.

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An antimagic labeling of a directed graph D with n vertices and m arcs is a bijection from the set of arcs of D to the integers {1, · · · , m} such that all n oriented vertex sums are pairwise distinct, where an oriented vertex sum is the sum of labels of all arcs entering that vertex minus the sum of labels of all arcs leaving it. An undirected graph G is said to have an antimagic orientation if G has an orientation which admits an antimagic labeling. Hefetz, Mütze, and Schwartz conjectured that every connected undirected graph admits an antimagic orientation. In this paper, we support this conjecture by proving that every biregular bipartite graph admits an antimagic orientation. toward this conjecture. Let G be a graph with n vertices other than K 2 . In 2004, Alon, Kaplan, Lev, Roditty, and Yuster [1] showed that there exists a constant c such that if G has minimum degree at least c · logn, then G is antimagic. They also proved that G is antimagic when the maximum degree of G is at least n − 2, and they proved that all complete multipartite graphs (other than K 2 ) are antimagic. The latter result of Alon et al.was improved by Yilma [14] in 2013.Apart from the above results on dense graphs, the antimagic labeling conjecture has been also verified for regular graphs. Started with Cranston [5] showing that every bipartite regular graph is antimagic, regular graphs of odd degree [6], and finally all regular graphs [3] were shown to be antimatic sequentially. For more results on the antimagic labeling conjecture for other classes of graphs, see [7,9,11,12].Hefetz, Mütze, and Schwartz [10] introduced the variation of antimagic labelings, i.e., antimagic labelings on directed graphs. An antimagic labeling of a directed graph with m arcs is a bijection from the set of arcs to the integers {1, ..., m} such that any two oriented vertex sums are pairwise distinct, where an oriented vertex sum is the sum of labels of all arcs entering that vertex minus the sum of labels of all arcs leaving it. A digraph is called antimagic if it admits an antimagic labeling. For an undirected graph G, if it has an orientation such that the orientation is antimagic, then we say G admits an antimagic orientation. Hefetz et al. in the same paper posted the following problems.Question 1 ([10]). Is every connected directed graph with at least 4 vertices antimagic?Conjecture 1.1 ([10]). Every connected graph admits an antimagic orientation.Parallel to the results the on antimagic labelling conjecture, Hefetz, Mütze, and Schwartz [10] showed that every orientation of a dense graph is antimagic and almost all regular graphs have an antimagic orientation. Particulary, they showed that every orientation of stars (other than K 1,2 ), wheels, and complete graphs (other than K 3 ) is antimagic. Observe that if a bipartite graph is antimagic, then it has an antimagic orientation obtained by directing all edges from one partite set to the other. Thus by the result of Cranston [5], regular bipartite graphs have an antimagic orientation. A bipartite g...