Leaching Properties of Estuarine Harbor Sediment Before and After Electrodialytic Remediation

Electrodialytic remediation (EDR) can be used to extract heavy metals from a variety of different media. In this work, contaminated harbor sediments from two locations in the United States and one in Norway were subjected to EDR, and were compared with batch extractions conducted with the sediment. pH-dependent leaching tests were used to evaluate changes in leaching properties of treated and control sediments. Significant fractions of total concentrations were removed during treatment (35–95% with an average of 75% for all sediments and elements investigated). The release of elements in pH-dependent leaching tests, however, demonstrated equal or greater leaching from treated sediments in the neutral pH range. Dissolved organic carbon appears to be a significant contributor to post-treatment increases in leaching, and dissolution of significant iron and aluminum sorption sites is hypothesized to also play a role. This research highlights the importance of understanding contaminant speciation and availability, as total metals concentrations, in this particular case, do not relate to estimates of the environmental availability of metals (total concentrations were typically two to three orders of magnitude greater than concentrations released during pH-dependent leaching)

Hierarchical solutions of the Sherrington-Kirkpatrick model: Exact asymptotic behavior near the critical temperature

We analyze the replica-symmetry-breaking construction in the Sherrington-Kirkpatrick model of a spin glass. We present a general scheme for deriving an exact asymptotic behavior near the critical temperature of the solution with an arbitrary number of discrete hierarchies of the broken replica symmetry. We show that all solutions with finite-many hierarchies are unstable and only the scheme with infinite-many hierarchies becomes marginally stable. We show how the solutions from the discrete replica-symmetry-breaking scheme go over to the continuous one with increasing the number of hierarchies.Comment: REVTeX4, 11 pages, no figure

Localist representation can improve efficiency for detection and counting

Almost all representations have both distributed and localist aspects, depending upon what properties of the data are being considered. With noisy data, features represented in a localist way can be detected very efficiently, and in binary representations they can be counted more efficiently than those represented in a distributed way. Brains operate in noisy environments, so the localist representation of behaviourally important events is advantageous, and fits what has been found experimentally. Distributed representations require more neurons to perform as efficiently, but they do have greater versatility

Correlations between hidden units in multilayer neural networks and replica symmetry breaking

We consider feed-forward neural networks with one hidden layer, tree architecture and a fixed hidden-to-output Boolean function. Focusing on the saturation limit of the storage problem the influence of replica symmetry breaking on the distribution of local fields at the hidden units is investigated. These field distributions determine the probability for finding a specific activation pattern of the hidden units as well as the corresponding correlation coefficients and therefore quantify the division of labor among the hidden units. We find that although modifying the storage capacity and the distribution of local fields markedly replica symmetry breaking has only a minor effect on the correlation coefficients. Detailed numerical results are provided for the PARITY, COMMITTEE and AND machines with K=3 hidden units and nonoverlapping receptive fields.Comment: 9 pages, 3 figures, RevTex, accepted for publication in Phys. Rev.

Poison plants of Western Australia - Cabbage poison (Velleia discophora F. Muell.)

Cabbage poison is a plant of bitter and disagreeable taste, not readily eaten by stock, but field evidence suggests that on occasions it may be responsible for moralities, particularly of sheep. It was first tested and found to be toxic in 1939, with material obtained from Koorda-Mollerin district

Poison plants of Western Australia: toxic plants of the genera gastrolobium and oxylobium

Since the early days of settlement in Western Australia very heavy stock losses have resulted from the many poisonous species of the two closely related genera, Gastrolobium and Oxylobium which, with two exceptions, are widely distributed throughout the southern areas of the State. They constitute the largest groups of native poisonous plants and have been responsible for a large proportion of the economic losses due to plant poisoning

Paspalum grass

Originally native to Uruguay and Argentina, Paspalum dilatatum was introduced into the U.S.A. about the middle of the 19th century and is now firmly established and cultivated in the Gulf States where it is known as Dallis erass after A. T. Dallis of La Grange, Georgia. It was introduced into Australia by Baron von Mueller about 1880 and since 1898 its cultivation has steadily increased

Poison plants of Western Australia: isotropis

The genus Isotropis is restricted to Australia. Of the total of nine species six are recorded in Western Australia, two of them being known as Lamb poisons while the remainder have no common names. Three are known to be toxic to stock, but concerning the remaining three we have no definite information. * Poison Plants of Western Australia is an ongoing series of articles. Toxic Plants of the Genus Isotropis is the subtitle and primary focus of this article

Poison plants of Western Australia: the thorn apples (datura species)

Many garden enthusiasts are familiar with a shrub or small tree known as the Angel\u27s Trumpet or Trumpet-flowered Brugmansia. Some nurserymen call it Brugsmania. There is another garden favourite which does not appear to possess a common name but is an annual or perennial plant from one to four feet in height, of summer growth and carrying erect violet or white trumpet-shaped flowers succeeded by large bristly or prickly pods. Both these are species of Datura. Another species is native to Western Australia while four more are introduced noxious weeds