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OBJECTIVENeuropathic pain due to small-fiber sensory neuropathy in type 2 diabetes can be diagnosed by skin biopsy with quantification of intra-epidermal nerve fiber (IENF) density. There is, however, a lack of noninvasive physiological assessment. Contact heat–evoked potential (CHEP) is a newly developed approach to record cerebral responses of Aδ fiber–mediated thermonociceptive stimuli. We investigated the diagnostic role of CHEP.RESEARCH DESIGN AND METHODSFrom 2006 to 2009, there were 32 type 2 diabetic patients (20 males and 12 females, aged 51.63 ± 10.93 years) with skin denervation and neuropathic pain. CHEPs were recorded with heat stimulations at the distal leg, where skin biopsy was performed.RESULTSCHEP amplitude was reduced in patients compared with age- and sex-matched control subjects (14.8 ± 15.6 vs. 33.7 ± 10.1 μV, P < 0.001). Abnormal CHEP patterns (reduced amplitude or prolonged latency) were noted in 81.3% of these patients. The CHEP amplitude was the most significant parameter correlated with IENF density (P = 0.003) and pain perception to contact heat stimuli (P = 0.019) on multiple linear regression models. An excitability index was derived by calculating the ratio of the CHEP amplitude over the IENF density. This excitability index was higher in diabetic patients than in control subjects (P = 0.023), indicating enhanced brain activities in neuropathic pain. Among different neuropathic pain symptoms, the subgroup with evoked pain had higher CHEP amplitudes than the subgroup without evoked pain (P = 0.011).CONCLUSIONSCHEP offers a noninvasive approach to evaluate the degeneration of thermonociceptive nerves in diabetic neuropathy by providing physiological correlates of skin denervation and neuropathic pain.

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An n-sun is the graph with 2n vertices consisting of an n-cycle with n pendent edges which form a 1-factor. In this paper we show that the necessary and sufficient conditions for the decomposition of complete tripartite graphs with at least two partite sets having the same size into 3-suns and give another construction to get a 3-sun system of order n, for n ≡ 0, 1, 4, 9 (mod 12). In the construction we metamorphose a Steiner triple system into a 3-sun system. We then embed a cyclic Steiner triple system of order n into a 3-sun system of order 2n − 1, for n ≡ 1 (mod 6).

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The direct simulation Monte Carlo (DSMC) method has been employed to analyze the rationality of the 2-D simplification for a 3-D straight rectangular cross-sectional channel. An implicit treatment for low-speed inflow and outflow boundaries for the DSMC of the microchannel flow is employed. The 3-D microchannel flows are simulated with cross aspect ratios in the range of 1 and 5. The calculated flow properties in the 3-D cases are compared with the results of the 2-D case. They show that when the aspect ratio <3, the two extra side walls in the 3-D case have significant effects on the heat transfer and flow properties. When the aspect ratio is increased, the flow pattern and heat transfer characteristics tend to approach those of 2-D results. The 2-D simplification is found to be reasonable only when the cross aspect ratio is greater than 5.