Reversal learning in pigeons: Effects of selective lesions of the Wulst.

Evaluated the effects of bilateral lesions of individual laminae of the Wulst on reversal-learning performance in pigeons. After surgery, Ss were trained to perform a simultaneous color discrimination. Once successful discrimination was achieved, the positive and negative stimuli were reversed, and Ss were again trained to criterion. 20 reversals were carried out. A multiple regression analysis indicated that those components of the Wulst that were critical for increasing the numbers of errors on each reversal were the laminae that receive the thalamofugal visual projections (i.e., the nucleus intercalatus of the hyperstriatum accessorium and the hyperstriatum dorsale). Lesions in the other laminae of the Wulst (the hyperstriatum accessorium and the hyperstriatum intercalatus superior) had no effect on errors. There was no evidence of an increase in either perseverative errors or position habits in the Ss with lesions, suggesting that the reversal deficits were not likely to be due to perseveration, attentional impairment, or inappropriate processing of spatial information. The deficit may have been produced by excessive interference between learning in a given session and learning in previous sessions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Postcyclic Recompression, Stiffness, and Consolidated Cyclic Strength of Silt

Low plasticity silts are liquefiable and the dissipation of pore pressures after an earthquake will be accompanied by densification and compression of the soil skeleton. Anisotropic rather than isotropic stress distributions are commonly found to exist in slopes or silty fills placed under K0 conditions and this can be enhanced further by the weight of overlying structures. Compression after an earthquake generally increases soil resistance but it can still be liquefied by aftershocks. The postcyclic recompression of silt, and postdrainage monotonic and cyclic strength and stiffness have therefore been investigated with respect to the effect of initial anisotropic consolidation. The compressibilities during postcyclic recompression were similar to those for isotropic consolidation. Samples with a greater initial anisotropy had less volumetric strain but larger axial strains during postcyclic drainage. Under stress reversal conditions failure occurred as a result of the development of double amplitude cyclic strains, whereas under nonreversal conditions compressive axial plastic strain was accumulated. Postdrainage second loading cyclic strength increased with increasing anisotropy. For isotropically consolidated samples failure under reversal cyclic loading resulted in a weaker soil structure even after postcyclic reconsolidation.     

On the k-tuple domination of de Bruijn and Kautz digraphs

In a digraph G, a vertex u is said to dominate itself and vertices v such that (u,v) is an arc of G. For a positive integer k, a k-tuple dominating set D of a digraph is a subset of vertices such that every vertex is dominated by at least k vertices in D. The k-tuple domination number of a given digraph is the minimum cardinality of a k-tuple dominating set of the digraph. In this letter, we give the exact values of the k-tuple domination number of de Bruijn and Kautz digraphs.     

Hamiltonian laceability of bubble-sort graphs with edge faults

It is known that the n-dimensional bubble-sort graph B_n is bipartite, (n − 1)-regular, and has n! vertices. We first show that, for any vertex v, B_n − v has a hamiltonian path between any two vertices in the same partite set without v. Let F be a subset of edges of B_n. We next show that B_n − F has a hamiltonian path between any two vertices of different partite sets if ∣F∣ is at most n − 3. Then we also prove that B_n − F has a path of length n! − 2 between any pair of vertices in the same partite set.     

Methane fermentation of a mixture of seaweed and milk at a pilot-scale plant

In this study, a pilot-scale plant was built to examine the practicality of producing biogas from seaweeds, widely available in Japan. Laminaria sp. and Ulva sp. seaweeds were mixed with other organic waste (milk) and used as fermentation materials. Though quantities and ratios of the materials were varied, the ratio of generated methane to input chemical oxygen demand (COD) was largely stable (0.2–0.3 m³ methane/kg COD) and the organic acid concentration in the methane fermentation solution was low (< 1200 ppm) during prolonged operation. These findings indicate that stable methane fermentation was achieved and that mixing with other organic material was effective in suppressing fluctuations in material amounts caused by the variable supply of seaweeds. Our results demonstrate the practical feasibility of biogas generation using seaweeds.     

Recovery of Platinum Group Metals from Spent Catalysts Using Iron Chloride Vapor Treatment

Metallurgical and Materials Transactions B - The recovery of platinum group metals (PGMs) from spent automobile catalysts is a difficult process because of their relatively low contents in the...     

Space charges remaining in polymers after electron beam irradiation and the role of conductivity in their decay profiles

Five typical insulating polymers and a carbon‐loaded polyethylene were irradiated with 200‐keV electrons, and the space charge distributions remaining in the polymers were measured. When the polymer film is short‐circuited after irradiation, the amount of space charge gradually decreases monotonically. By analyzing such decay profiles, it becomes clear that the decay of the charges remaining after the irradiation is governed by the conductivity of the polymer. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Synthesis and characterization of metal ions containing hydroxyapatite microparticles with high specific surface area

Zinc and/or iron ions containing hydroxyapatite (HA) microparticles, which had twice as high specific surface area and higher pore volumes compared with the pure HA, were fabricated by a spray drying method; the zinc and/or iron ions were incorporated into the constitutional nanocrystals with below 20 nm in size in preparing. The small amount of carbonate ions was substituted in the phosphate group. The particle sizes were distributed in the range of 1 to 20 microm in diameter and its averaged size was approximately 6 microm. The microparticles with a spherical shape showed a single phase of HA and, after treated at higher temperature than 800 degrees C, had the high crystallite HA and the other phase of metal oxide such as ZnO or Fe2O3. The microparticles with higher specific surface area will be applicable for the drug delivery carriers of proteins.     

Encapsulation of hemoglobin in mesoporous silica (FSM)-enhanced thermal stability and resistance to denaturants

Hemoblogin (Hb), which is a typical oligomeric protein, was introduced into the pores of mesoporous silica (FSM: folded-sheet mesoporous material) that had a diameter of 7.5 nm. Soret CD spectra of Hb-FSM-7.5 conjugates showed a peak that was identical to that of free Hb. This suggests that Hb retained its highly ordered structure in the mesoporous silica. In addition, the UV-visible absorption spectrum showed that Hb had an increased resistance to heat denaturation in the silica. Even after heat treatment at 85 degrees C, Hb-FSM-7.5 retained its ligand-binding activity. The stability of Hb-FSM-7.5 was examined further by measuring its peroxidase-like activity. Encapsulation of Hb resulted in the retention of activity in the presence of high NaCl or Gdn-HCl levels. This suggests that encapsulation prevented dissociation and denaturing. Thus, it seems that the mesopores created a favorable environment for the oligomeric protein to perform its function, even under harsh conditions.