Development of path loss model for 802.11n in large conference rooms

In this paper, a path loss (PL) model for 802.11n in large conference rooms is determined, based on PL measurements. The PL can be described accurately by a one-slope model with one standard deviation. PL exponents varying from 1.2 to 1.7 are found. Based on this PL model, the effect of frequency (2.4 vs 5 GHz), configuration (SISO vs MIMO (spatial diversity)), bandwidth (20 vs 40 MHz) and transmit power on number of access points, total power consumption and possible (physical) throughputs is investigated. According to the determined PL model, a higher range (by tuning the transmit power) requires less access points, as well as a lower total power consumption, due to a PL exponent lower than 2

Creatine and glycerol hyperhydration in trained subjects prior to exercise in the heat.

The authors examined the effects of combined creatine (Cr) and glycerol (Gly) supplementation on responses to exercise in the heat. Subjects (N = 24) were matched for body mass and assigned to either a Cr or placebo (Pl) group. Twice daily during two 7-d supplementation regimens, the Cr group received 11.4 g of Cr·H2O and the Pl group received 11.4 g of glucose. Subjects in both groups also ingested 1 g of Gly/kg body mass (twice daily) in either the first or the second supplementation regimen. This design allowed 4 possible combinations of supplements to be examined (Pl/Pl, Pl/Gly, Cr/Pl, and Cr/Gly). Exercise trials were conducted pre- and postsupplementation at 30 °C and 70% relative humidity. In the Pl group, total body water (TBW) increased by 0.50 ± 0.28 L after Gly and in the Cr group by 0.63 ± 0.33 L after Pl and by 0.87 ± 0.21 L after Gly. Both Cr/Pl and Cr/Gly resulted in significantly attenuated heart rate, rectal temperature, and perceived effort during exercise, although no regimen had any effect on performance. The addition of Gly to Cr significantly increased TBW more than Cr alone (P = 0.02) but did not further enhance the attenuation in HR, Tre, and RPE during exercise. These data suggest that combined Cr and Gly is an effective method of hyperhydration capable of reducing thermal and cardiovascular strain

Some questions about the dimension of a group action

We discuss three families of groups, $ZW_n$, $PL(I^n)$, and $PL(S^n)$ (the last two being families of groups of piecewise-linear homeomorphisms of standard $n$-dimensional spaces). We note that for all positive integers $n$, $ZW_n$ embeds in $PL(I^n)$ which embeds in $PL(S^n)$. In another direction, $ZW_2$ fails to embed in $PL(I^1)$ by an earlier result of the author, and we extend that result to show that $ZW_2$ also fails to embed in $PL(S^1)$. The nature of the proofs of these non-embedding results leads us to ask if there are corresponding non-embedding results in higher dimensions.Comment: 8 Pages, follows up on some loose ideas in "A geometric classification of some solvable groups of homeomorphisms." Arxiv: math.GR/060203

Piecewise-linear pseudodiagrams

There are 2^n possible resolutions of a smooth pseudodiagram with n precrossings. If we consider piecewise-linear (PL) pseudodiagrams and resolutions that themselves are PL, certain resolutions of the pseudodiagram may not exist in three-space. We investigate this situation and its impact on the weighted resolution set of PL pseudodiagrams as well as introduce a concept specific to PL pseudodiagrams, the forcing number. Our main result classifies the PL shadows whose weighted resolution sets differ from the weighted resolution set that would exist in the smooth case.Comment: 7 pages, 8 figures; V2 fixes a minor typo in both statement of Cor. 2.8 and in its proo