Resonant electron transmission through a finite quantum spin chain

Electron transport in a finite one dimensional quantum spin chain (with ferromagnetic exchange) is studied within an $s-d$ exchange Hamiltonian. Spin transfer coefficients strongly depend on the sign of the $s-d$ exchange constant. For a ferromagnetic coupling, they exhibit a novel resonant pattern, reflecting the salient features of the combined electron-spin system. Spin-flip processes are inelastic and feasible at finite voltage or at finite temperature.Comment: 4 pages including 4 .eps figure

Recent Decisions

Comments on recent decisions by Richard M. Di Valerio, James A. Uhl, Donald J. Prebenda, Wilbur L. Pollard, William N. Antonis, Richard E. Shipman, Richard D. Heman, Thomas P. Meaney, Jr., John A. Pietrykowski, and Richard F. Welter

Electron emission into dielectric liquids

The current between polished nickel electrodes immersed in pure toluene has been measured as a function of electric field (over the range 0 to 250,000 volts/cm) and of temperature (from - 15 to 70°C). The Richardson lines are straight but show a very small slope (0.05 to 0.4 ev) and a small value of the constant A (10^-9 to 10^-11 amp./cm^2 deg.^2). The logi vs. E1 / 2 curves show a slope about twice the value e3 / 2 / D1 / 2kT predicted by the simple Schottky theory, but in agreement with the theory of Baker and Boltz. It is found however that there are serious objections to this theory, and the agreement with it is probably accidental. The situation is in fact too complex to be handled by a simple theory. It is suggested that for the low potential barrier present at the metal-dielectric interface a combination of thermionic and field currents would be expected which would account qualitatively for the observed behavior

Base Exchange Between Dyes and Soils

Beaumont, Rohland and Wilkinson and Hoff have shown the effect of acidity and alkalinity of solutions on the adsorption of dyes by soils. Ashley found that during the adsorption of basic dyes by soils the dyes exchanged some of their positive ions for the metal ions of the soil thus fixing some of the dye by base-exchange. Wilkinson and Hoff found that a methylene blue solution liberates more calcium and magnesium from a soil than does distilled water alone. Sante Mattson found in the case of two soils that the methylene blue adsorbed was approximately equivalent to the monovalent and divalent bases that were set free. The purpose of this investigation is to determine quantitatively the relationship between the equivalents of dye adsorbed and the negative and metal ions liberated from several soils with two basic dyes and by comparison from this data find the fraction of the dye that is taken up by base-exchange and the fraction held in some other way

Nephrotoxicity in Patients With or Without Cystic Fibrosis Treated With Polymyxin B Compared to Colistin

Nephrotoxicity is the primary adverse effect of the polymyxins. The relative rates of toxicity of polymyxin B and colistin have not been fully elucidated, especially in patients with cystic fibrosis (CF). A retrospective cohort study of adults treated with polymyxin B or colistin for at least 48 h was conducted. The primary endpoint was the incidence of kidney injury assessed by RIFLE (i.e., risk, injury, failure, loss, end-stage renal disease) criteria. Risk factors for kidney injury were evaluated using multivariate Cox regression. A total of 414 patients were evaluated, 220 of whom had CF. In patients without CF, there was no difference in kidney injury with polymyxin B and colistin (42.9% versus 50.3%, P = 0.46). Loop diuretic exposure was a risk factor for kidney injury (adjusted hazard ratio [aHR], 1.82; 95% confidence interval [CI], 1.16 to 2.83) in this population. In patients with CF, polymyxin B and colistin were associated with similar rates of kidney injury (34.5% versus 29.8%, P = 0.77). Diabetes (aHR, 2.68; 95% CI, 1.01 to 7.11), loop diuretics (aHR, 3.02; 95% CI, 1.36 to 6.73), and progressive care unit admission (aHR, 8.21; 95% CI, 2.55 to 26.46) were risk factors for kidney injury, while higher baseline serum creatinine levels (per 1 mg/dl) were protective (aHR, 0.08; 95% CI, 0.01 to 0.48). Total unadjusted kidney injury in polymyxin-treated patients was less frequent in those who had CF (30.5% versus 48.5%, P \u3c 0.001). Polymyxin B and colistin are associated with a high incidence of kidney injury; cystic fibrosis may be protective against polymyxin nephrotoxicity, but further investigation is needed to confirm this conjecture

A Spontaneous Fatp4/Scl27a4 Splice Site Mutation in a New Murine Model for Congenital Ichthyosis

Congenital ichthyoses are life-threatening conditions in humans. We describe here the identification and molecular characterization of a novel recessive mutation in mice that results in newborn lethality with severe congenital lamellar ichthyosis. Mutant newborns have a taut, shiny, non-expandable epidermis that resembles cornified manifestations of autosomal-recessive congenital ichthyosis in humans. The skin is stretched so tightly that the newborn mice are immobilized. The genetic defect was mapped to a region near the proximal end of chromosome 2 by SNP analysis, suggesting Fatp4/Slc27a4 as a candidate gene. FATP4 mutations in humans cause ichthyosis prematurity syndrome (IPS), and mutations of Fatp4 in mice have previously been found to cause a phenotype that resembles human congenital ichthyoses. Characterization of the Fatp4 cDNA revealed a fusion of exon 8 to exon 10, with deletion of exon 9. Genomic sequencing identified an A to T mutation in the splice donor sequence at the 3′-end of exon 9. Loss of exon 9 results in a frame shift mutation upstream from the conserved very long-chain acyl-CoA synthase (VLACS) domain. Histological studies revealed that the mutant mice have defects in keratinocyte differentiation, along with hyperproliferation of the stratum basale of the epidermis, a hyperkeratotic stratum corneum, and reduced numbers of secondary hair follicles. Since Fatp4 protein is present primarily at the stratum granulosum and the stratum spinosum, the hyperproliferation and the alterations in hair follicle induction suggest that very long chain fatty acids, in addition to being required for normal cornification, may influence signals from the stratum corneum to the basal cells that help to orchestrate normal skin differentiation