New conserved vorticity integrals for moving surfaces in multi-dimensional fluid flow

For inviscid fluid flow in any n-dimensional Riemannian manifold, new conserved vorticity integrals generalizing helicity, enstrophy, and entropy circulation are derived for lower-dimensional surfaces that move along fluid streamlines. Conditions are determined for which the integrals yield constants of motion for the fluid. In the case when an inviscid fluid is isentropic, these new constants of motion generalize Kelvin’s circulation theorem from closed loops to closed surfaces of any dimension.

The electromyographic threshold in boys and men

Abstract Background Children have been shown to have higher lactate (LaTh) and ventilatory (VeTh) thresholds than adults, which might be explained by lower levels of type-II motor-unit (MU) recruitment. However, the electromyographic threshold (EMGTh), regarded as indicating the onset of accelerated type-II MU recruitment, has been investigated only in adults. Purpose To compare the relative exercise intensity at which the EMGTh occurs in boys versus men. Methods Participants were 21 men (23.4 ± 4.1 years) and 23 boys (11.1 ± 1.1 years), with similar habitual physical activity and peak oxygen consumption (VO2pk) (49.7 ± 5.5 vs. 50.1 ± 7.4 ml kg−1 min−1, respectively). Ramped cycle ergometry was conducted to volitional exhaustion with surface EMG recorded from the right and left vastus lateralis muscles throughout the test (~10 min). The composite right–left EMG root mean square (EMGRMS) was then calculated per pedal revolution. The EMGTh was then determined as the exercise intensity at the point of least residual sum of squares for any two regression line divisions of the EMGRMS plot. Results EMGTh was detected in 20/21 of the men (95.2 %) and only in 18/23 of the boys (78.3 %). The boys’ EMGTh was significantly higher than the men’s (86.4 ± 9.6 vs. 79.7 ± 10.0 % of peak power output at exhaustion; p < 0.05). The pattern was similar when EMGTh was expressed as percentage of VO2pk. Conclusions The boys’ higher EMGTh suggests delayed and hence lesser utilization of type-II MUs in progressive exercise, compared with men. The boys–men EMGTh differences were of similar magnitude as those shown for LaTh and VeTh, further suggesting a common underlying factor.

View of Falls from Steel Bridge, Niagara, U.S.A.

The description of the image reads "(4)-8972-General view of Falls from new steel bridge - Maid of the Mist at landing - Niagara, U.S.A." The reverse of the image includes the description, "We are standing on the new steel bridge over Niagara River, 190 feet above the water and looking a little west of south, up the river towards Lake Erie. The high cliff at the extreme left, on the American side, is Prospect Point, where a crowd is gathered at this moment to view the Falls that we see just beyond Prospect Point. That dark, tree-covered mass of rock beyond is Goat Island; and just this side of Goat Island we see a bit of its precipice has been cut off separate from the rest by the powerful current of the waters - the smaller portion is Luna Island, and the Luna Falls go pouring down between the two islands. The face of the precipice curves inward beneath the Luna Falls leaving behind the 160 foot sheet of water the unearthly hollow known as the Cave of the Winds. Beyond Goat Island we see the gigantic curve of the Horseshoe Falls, 3,010 feet long and 158 feet high, reaching around through the clouds of spray to the farther Canadian shore. (The boundary line between British and American territory is in mid-stream.) It has been estimated that every minute 375,000 tons of water pour over these Horseshoe Falls, and they are wearing away the cliffs, moving back up the stream at the rate of 2.4 feet per year. It was probably only about a thousand years ago that they took their plunge just about where we stand now. Down there below us, at the wharf is the Maid of the Mist at the American landing taking on passengers who have come down the steep bank by the inclined railway. Its course takes it through those clouds of spray almost to the very foot of both Falls, - waters falling from 167 feet overhead, and water surging at least as many feet deep under the staunch little vessel. See special 'keyed' maps of Niagara pub. by Underwood and Underwood, also the Niagara Book by Mark Twain, W.D. Howells and others."

Internationalization in German Academic Libraries: Moving beyond North American Perspectives

This paper explores how internationalization is understood and experienced in German academic libraries. Its main purpose is to move the discussion of internationalization in academic libraries beyond the boundaries of English-speaking North America by investigating a European perspective. Its secondary purpose is to investigate the role of English in German academic libraries. An online survey and a series of in-person interviews conducted in Germany in April 2015 provided the data for this study. What emerged are a series of stated differences and similarities between North America and Germany informed by the two overarching themes of implicit internationalization and plurilingualism, the ability to switch from one language to another as required.

License no. 144 of season 1872/73 made out to S.D. Woodruff for 36 square miles in berth no. 192

License no. 144 of season 1872/73 made out to S.D. Woodruff for 36 square miles in berth no. 192. This document is slightly torn and stained along the right hand side. This does not affect the text, April 7, 1873.

License no. 145 of season 1872/73 made out to S.D. Woodruff for 35 ¾ square miles in berth no. 198

License no. 145 of season 1872/73 made out to S.D. Woodruff for 35 ¾ square miles in berth no. 198, April 7, 1873.

License no. 67 of season 1873/74 made out to S.D. Woodruff for 36 square miles in berth no. 192

License no. 67 of season 1873/74 made out to S.D. Woodruff for 36 square miles in berth no. 192, June 13, 1873

License no. 68 of season 1873/74 made out to S.D. Woodruff for 35 ¾ square miles in berth no. 198

License no. 68 of season 1873/74 made out to S.D. Woodruff for 35 ¾ square miles in berth no. 198, June 13, 1873.

License no. 11 of season 1874/75 made out to S.D. Woodruff for 35 ¾ square miles in berth no. 198

License no. 11 of season 1874/75 made out to S.D. Woodruff for 35 ¾ square miles in berth no. 198, May 20, 1874.

License no. 5 of season 1875/76 made out to S.D. Woodruff for 36 square miles in berth no. 192

License no. 5 of season 1875/76 made out to S.D. Woodruff for 36 square miles in berth no. 192, June 1, 1875.

License no. 2 of season 1886/87 made out to S.D. Woodruff for 36 square miles in berth no. 192

License no. 2 of season 1886/87 made out to S.D. Woodruff for 36 square miles in berth no. 192, May 15, 1876.

License no. 3 of season 1886/87 made out to S.D. Woodruff for 35 ¾ square miles in berth no. 198

License no. 3 of season 1886/87 made out to S.D. Woodruff for 35 ¾ square miles in berth no. 198, May 15, 1876

License no. 7 of season 1877/78 made out to S.D. Woodruff for 35 ¾ square miles in berth no. 198

License no. 7 of season 1877/78 made out to S.D. Woodruff for 35 ¾ square miles in berth no. 198, May 31, 1877.

License no. 6 of season 1877/78 made out to S.D. Woodruff for 36 square miles in berth no.192

License no. 6 of season 1877/78 made out to S.D. Woodruff for 36 square miles in berth no.192, May 31, 1877.

License no. 87 of season 1879/80 made out to S.D. Woodruff for 36 square miles in berth no. 192

License no. 87 of season 1879/80 made out to S.D. Woodruff for 36 square miles in berth no. 192, June 3, 1879.