Boundary Pressure Fluctuations Due to Macroturbulence in Hydraulic Jumps

Data concerning the statistical properties of pressure fluctuations on the containment structure associated with the hydraulic jump have been studied at the St. Anthony Falls Hydraulic Laboratory. The incident Froude numbers were investigated through the practical range from 4 to 9. The mean square of the fluctuating pressure, the mean pressure, and the power spectrum were determined as a function of position under the jump. In addition, mean and rms turbulent velocity profiles and entrained air concentration profiles throughout the jump volume were determined. The principal tests were performed in a channel 20 inches wide and 3 feet deep. Other tests at a larger scale were performed in a flume 9 feet wide and 6 feet deep to assist in an evaluation of the scaling properties of the various statistical parameters. The data indicate that the rapid rate of energy dissipation near the toe of the jump leads to a maximum rms fluctuation pressure on the bed of about 5 per cent of the incoming velocity head. The location of the maximum pressure fluctuation is approximately midway under the roller of the jump

Precedings of Arkansas Lakes Symposium Limnological Studies of Lake Chicot, Arkansas

Lake Chicot is an oxbow lake that was created more than 600 years ago by the meandering of the Mississippi River. It is located in Chicot county in southeastern Arkansas adjacent to the present Mississippi River. As the largest natural lake in Arkansas it earned an early reputation for its good fishing and recreational value. Development of a levee system forced the enlargement of the lakes watershed to its present 350 square miles. Initially this alteration affected only the volume flow through the lake, drastically reducing the water residence time. Because the watershed was located in one of the most agriculturally productive regions in the world, the land, predominantly comprised of clay and fine silts, quickly became more intensively farmed. The use of agricultural chemicals increased, large amounts of sediments were produced and the lake began to become severely impacted by this activity

can concomitant diseases predict the compliance with cisplatin plus rt in patients with la scchn an exploratory endpoint analysis of the comply trial

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ИССЛЕДОВАНИЕ И ОПИСАНИЕ БЫТОВЫХ ГАЗОВЫХ СЧЕТЧИКОВ

В работе описывается исследование бытовых газовых счетчиков, их разновидности по принципу действия, основные преимущества и их метрологические характеристики. А также рассмотрены характеристики природного газа

Volatile Organic Compounds Emitted by Fungal Associates of Conifer Bark Beetles and their Potential in Bark Beetle Control

Conifer bark beetles attack and kill mature spruce and pine trees, especially during hot and dry conditions. These beetles are closely associated with ophiostomatoid fungi of the Ascomycetes, including the genera Ophiostoma, Grosmannia, and Endoconidiophora, which enhance beetle success by improving nutrition and modifying their substrate, but also have negative impacts on beetles by attracting predators and parasites. A survey of the literature and our own data revealed that ophiostomatoid fungi emit a variety of volatile organic compounds under laboratory conditions including fusel alcohols, terpenoids, aromatic compounds, and aliphatic alcohols. Many of these compounds already have been shown to elicit behavioral responses from bark beetles, functioning as attractants or repellents, often as synergists to compounds currently used in bark beetle control. Thus, these compounds could serve as valuable new agents for bark beetle management. However, bark beetle associations with fungi are very complex. Beetle behavior varies with the species of fungus, the stage of the beetle life cycle, the host tree quality, and probably with changes in the emission rate of fungal volatiles. Additional research on bark beetles and their symbiotic associates is necessary before the basic significance of ophiostomatoid fungal volatiles can be understood and their applied potential realized

A human muscle Na+ channel mutation in the voltage sensor IV/S4 affects channel block by the pentapeptide KIFMK

Whole cell patch clamping of transfected HEK293 cells was used to examine the effects of a pentapeptide (KIFMK) containing the proposed inactivation particle of the Na+ channel on two mutations causing myotonia. One mutation (R1448P) is located in the voltage sensor IV/S4, and the other one (G1306E) near the postulated inactivation gate within the III-IV linker.In the absence of peptide, currents of wild-type (WT) and mutant human muscle Na+ channels decayed monoexponentially with inactivation time constants that were 5-fold (R1448P) and 3-fold (G1306E) larger for the mutants. Upon intracellular application of KIFMK (0·3-1 mM) the current decay became biexponential with an additional fast decaying component that increased in amplitude with depolarization.Furthermore, the peptide induced large tail currents upon repolarization, indicating that KIFMK prevents inactivation by blocking open Na+ channels. The peak of this tail current decreased only slowly with depolarizations of increasing duration. The voltage dependence of this decline indicated that the dissociation rate of the charged peptide decreased with depolarization. Increased external [Na+] ([Na+]e) antagonized block by KIFMK, consistent with a pore-blocking mechanism.The results are discussed with regard to a three-state model for one open, an absorbing inactivated and one blocked state with voltage-dependent on- and off-rates for peptide binding. The peptide had qualitatively similar effects on WT and both mutants, indicating that the freely diffusible peptide accelerates the current decay in all three clones. However, for the R1448P mutation the affinity for KFIMK was decreased and the voltage dependence of peptide block was changed in a similar way to the voltage dependence of inactivation. These data suggest that the mutation R1448P affects the voltage-dependent formation of a receptor site for both the inactivation particle and KIFMK