Enhanced and reduced transmission of acoustic waves with bubble meta-screens

We present a class of sonic meta-screens for manipulating air-borne acoustic waves at ultrasonic or audible frequencies. Our screens consist of periodic arrangements of air bubbles in water or possibly embedded in a soft elastic matrix. They can be used for soundproofing, but also for exalting transmission at an air/water interface or even to achieve enhanced absorption

Impact of the European Russia drought in 2010 on the Caspian Sea level

This article has been made available through the Brunel Open Access Publishing Fund - Copyright @ 2011 Arpe et al.The hydrological budgets of the Volga basin (VB) and the Caspian Sea (CS) have been analysed. The components of the water balance for the CS were calculated for the period 1993 to 2010 with emphasis on summer 2010 when a severe drought developed over European Russia. A drop in precipitation over the VB in July 2010 occurs simultaneously with a decrease in evaporation for the same area, an increase of evaporation over the CS itself and a drop of the Caspian Sea level (CSL). The drop in the precipitation over the VB cannot lead to an instantaneous drop of the CSL because the precipitated water needs some months to reach the CS. The delay is estimated here to be 1 to 3 months for excessive precipitation in summer, longer for deficient precipitation and for winter cases. However, the evaporation over the CS itself is considered to be responsible for a simultaneous drop of the CSL from July to September 2010. The impact on the CSL from the precipitation deficit over the VB occurs in the months following the drought. The water deficit from July to September 2010 calculated from the anomalous precipitation minus evaporation over the VB would decrease the CSL by 22 cm, of which only 2 cm had been observed until the end of September (observed Volga River discharge anomaly). So the remaining drop of 20 cm can be expected in the months to follow if no other anomalies happen. In previous studies the precipitation over the VB has been identified as the main cause for CSL changes, but here from a 10 cm drop from beginning of July to end of September, 6 cm can be directly assigned to the enhanced evaporation over the CS itself and 2 cm due to reduced precipitation over the CS. Further periods with strong changes of the CSL are also investigated, which provide some estimates concerning the accuracy of the analysis data. The investigation was possible due to the new ECMWF interim reanalysis data which are used to provide data also for sensitive quantities like surface evaporation and precipitation. The comparison with independent data and the consistency between such data for calculating the water budget over the CS gives a high confidence in the quality of the data used. This investigation provides some scope for making forecasts of the CSL few months ahead to allow for mitigating societal impacts.This article is a contribution to the European project Marie Curie, CLIMSEAS – PIRSES-GA-2009-247512: “Climate Change and Inland Seas: Phenomena, 20 Feedback and Uncertainties. The Physical Science Basis”

Magnetic Field-Vector Measurements in Quiescent Prominences via the Hanle Effect: Analysis of Prominences Observed at Pic-Du-Midi and at Sacramento Peak

The Hanle effect method for magnetic field vector diagnostics has now provided results on the magnetic field strength and direction in quiescent prominences, from linear polarization measurements in the He I E sub 3 line, performed at the Pic-du-Midi and at Sacramento Peak. However, there is an inescapable ambiguity in the field vector determination: each polarization measurement provides two field vector solutions symmetrical with respect to the line-of-sight. A statistical analysis capable of solving this ambiguity was applied to the large sample of prominences observed at the Pic-du-Midi (Leroy, et al., 1984); the same method of analysis applied to the prominences observed at Sacramento Peak (Athay, et al., 1983) provides results in agreement on the most probable magnetic structure of prominences; these results are detailed. The statistical results were confirmed on favorable individual cases: for 15 prominences observed at Pic-du-Midi, the two-field vectors are pointing on the same side of the prominence, and the alpha angles are large enough with respect to the measurements and interpretation inaccuracies, so that the field polarity is derived without any ambiguity

A Characterization of Infinite LSP Words

G. Fici proved that a finite word has a minimal suffix automaton if and only if all its left special factors occur as prefixes. He called LSP all finite and infinite words having this latter property. We characterize here infinite LSP words in terms of $S$-adicity. More precisely we provide a finite set of morphisms $S$ and an automaton ${\cal A}$ such that an infinite word is LSP if and only if it is $S$-adic and all its directive words are recognizable by ${\cal A}$

Influence of positional correlations on the propagation of waves in a complex medium with polydisperse resonant scatterers

We present experimental results on a model system for studying wave propagation in a complex medium exhibiting low frequency resonances. These experiments enable us to investigate a fundamental question that is relevant for many materials, such as metamaterials, where low-frequency scattering resonances strongly influence the effective medium properties. This question concerns the effect of correlations in the positions of the scatterers on the coupling between their resonances, and hence on wave transport through the medium. To examine this question experimentally, we measure the effective medium wave number of acoustic waves in a sample made of bubbles embedded in an elastic matrix over a frequency range that includes the resonance frequency of the bubbles. The effective medium is highly dispersive, showing peaks in the attenuation and the phase velocity as functions of the frequency, which cannot be accurately described using the Independent Scattering Approximation (ISA). This discrepancy may be explained by the effects of the positional correlations of the scatterers, which we show to be dependent on the size of the scatterers. We propose a self-consistent approach for taking this "polydisperse correlation" into account and show that our model better describes the experimental results than the ISA

G79-445 Soybean Variety Selection

This NebGuide has information on soybean characteristics that should be considered before selecting a variety to plant. Soybean characteristics that need to be considered in making the selection of a variety to plant include maturity, yield potential, plant type, height, seed size, emergence score, lodging, shattering, and disease and insect resistance. Many years are required to develop a new variety from the time an initial cross of soybeans is made until the time seed is available on a widespread basis. The advance of a potential variety through the early generations may be accomplished with only a few seeds of the selection being available through various levels of yield testing, followed by an increase of the seed to produce breeder seed, then to produce foundation, registered, and certified seed. All through these stages of development, the variety is evaluated for the many parameters of performance so that at time of release, the performance of the new variety is well documented

The Fox and the Hyenas

In late October of 1884 a huge parade wended its muddy way in a heavy rain down the streets of New York City. A fascinated English visitor watched as a thousand lawyers chanted their ridiculous: Blaine, Blaine, James G. BlaineWe don\u27t care a bit for the rain,O-O-O-O-HI-O The visitor knew they were celebrating the state of Ohio voting in favor of James G. Blaine for the presidency. Modern historians are just as amazed as was James Bryce, the first Viscount Bryce, when he described this unreal scene in his classic work, The American Commonwealth. Who was Blaine and what does he have to do with Ohio? Did Blaine ever do anything worth remembering? is the type of question the ordinary person might reasonably ask. Why did such an obvious scoundrel elicit such a fanatical following in the America of the 1880s asks the older historian. James G. Blaine was the best known and most enthusiastically supported American politician of his day. Only an inopportune sickness kept him from being the Republican presidential candidate in 1876. When he failed as front runner to gain the candidacy in 1880, he threw his votes to Garfield, assuring that Garfield would be president. In 1884 Blaine barely lost (1,047 votes in the crucial New York State tally) the presidential election. In 1888 he refused to run for president although his election seemed certain. It should be profitable for historians to explore Blaine\u27s connections with the politicians from the great state of Ohio, which is fairly typical of the older Western or Middle States (Lord Bryce\u27s description). The focus here will be narrowed to the view on this subject then emanating from the leading comic journal of America, Puck magazine. Although Puck prided itself as a historian of the entire age, yet it is widely accepted that its greatest moments were its pictorial struggles against James G. Blaine and his friends

The Pastor\u27s Relation to the Sunday School in the Oregon Yearly Meeting of Friends

The serious mistake has often been made in thinking that the Sunday School and the church were two separate and independent organisations, where the superintendent has been the leader of the former and the pastor the leader of the later. It was the concern of the writer to help bridge this gulf, to encourage the pastor and superintendent to work hand in hand, and to improve the methods whereby I this may be attained. Where there has been a strong and efficient Sunday School there has been a successful church