Intestinal Electric Stimulation Accelerates Whole Gut Transit and Promotes Fat Excrement in Conscious Rats

*_Introduction:_* Intestinal electric stimulation (IES) is proposed as a potential tool for the treatment of morbid obesity. Our previous study showed that IES with one pair of electrodes accelerated intestinal transit and decreased fat absorption in a segment of the jejunum in the anesthetized rats. The aims of this study were to assess the effects of IES on the whole gut transit and fat absorption in conscious rats, to examine the effects of multi-channel IES, and to explore the cholinergic mechanism behind the effects of IES. 
*_Methods:_* Thirty-eight male rats implanted with serosal electrodes were randomized into five groups: control without IES, 2/3 channel IES with short pulses, atropine and atropine plus IES. The whole gut transit and fat remained and emptied from the gut were analyzed after continuous 2-hour IES. 
*_Results:_* Two and three channel IES significantly accelerated phenol red (marker used for transit) excretion (ANOVA, P < 0.001). No significant difference was found between two and three channel IES. Two channel IES significantly increased the excretion of fat (P < 0.05). Atropine significantly blocked the accelerated transit induced by IES (ANOVA, P < 0.001). Correlation was found between the percentage of phenol red and fat retained in the whole gut (r = 0.497, P < 0.01). 
*_Conclusions:_* IES accelerates whole gut transit and promotes fat excrement in conscious rats, and these effects are mediated through the cholinergic nerves. These findings are in support of the concept that IES may be a promising treatment option for obesity

Note on Divergence of the Chapman-Enskog Expansion for Solving Boltzmann Equation

Within about a year (1916-1917) Chapman and Enskog independently proposed an important expansion for solving the Boltzmann equation. However, the expansion is divergent or indeterminant in the case of relaxation time $\tau \geq 1$. Even since this divergence problem has puzzled this subject for a century. By using a modified M\"obius series inversion formula, this paper proposes a modified Chapman-Enskog expansion with a variable upper limit of the summation. The new expansion can give not only a convergent summation but also provide the best-so-far explanation on some unbelievable scenarios occurred in previous practice.Comment: 4 pages, 0 figures, 2 table

Note on DBI dynamics of Dbrane Near NS5-branes

In this note, we investigate the homogeneous radial dynamics of (Dp, NS5)-systems without and with one compactified transverse direction, in the framework of DBI effective action. During the homogeneous evolution, the electric field on the D-brane is always conserved and the radial motion could be reduced to an one-dimension dynamical system with an effective potential. When the Dp-brane energy is not high, the brane moves in a restricted region, with the orbits depending on the conserved energy, angular momentum through the form of the effective potential. When the Dp-brane energy is high enough, it can escape to the infinity. It turns out that the conserved angular momentum plays an interesting role in the dynamics. Moreover, we discuss the gauge dynamics around the tachyon vacuum and find that the dynamics is very reminiscent of the string fluid in the rolling tachyon case.Comment: 13 pages, 2 figures; typos corrected, discussions improved; gauge dynamics has been include