3,139 research outputs found
Critical fluctuations and quenched disordered two-dimensional charge stripes in La5/3Sr1/3NiO4
[[abstract]]Using high-resolution x-ray scattering, we have demonstrated the existence of quenched disordered charge stripes in a single crystal of La5/3Sr1/3NiO4 at low temperatures. Above the second-order transition critical scattering was observed due to fluctuations into the charge stripe phase. The charge stripes are shown to be two dimensional in nature both by measurements of their correlation lengths (xi(a) approximate to 185 Angstrom, xi(b) = 400 Angstrom, and xi(c) approximate to 25 Angstrom) and by the critical exponents of the charge strip transition. The charge stripe orderings did not develop long-range order even at low temperatures, indicating that the charge stripes are disordered and that the length scale of the disorder is quenched.[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子
Encouraging Revegetation in Australia with a Groundwater Recharge Credit Scheme
This paper describes a comprehensive method to design, test and then implement a Payments for Ecosystem Services (PES) framework to combat the environmental consequences of extensive native vegetation clearance in Australia. Clearing of vegetation, primarily due to the expansion of farming areas, has often resulted in regional dryland and irrigation salinity. The market based approach adopted ? a groundwater recharge credit trading scheme ? was designed using empirical data from a social survey and experimental economics. The objective of the trial is to test the cost effectiveness of an incentive based recharge credit trade scheme designed to engage landholders in establishing and managing deep rooted pasture and woody perennials to reduce these adverse salinity impacts. The scheme, based on a voluntary ?cap and trade? approach, allows farmers to meet recharge obligations by land management actions or by trading credits. Assessment of the scheme so far suggests that an incentive for aggregate group outcome achievement included in the design may have motivated higher enrollment rates than would have otherwise resulted. A schedule has been developed relating land management practices and recharge credits. The audited performance based payment system, has provided increased motivation to manage for environmental outcomes compared to the previous policy.Payments for Ecosystem Services (PES), market based instrument, cap and trade, salinity credit, revegetation, experimental economics
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Continuum sea ice rheology determined from subcontinuum mechanics
[1] A method is presented to calculate the continuum-scale sea ice stress as an imposed, continuum-scale strain-rate is varied. The continuum-scale stress is calculated as the area-average of the stresses within the floes and leads in a region (the continuum element). The continuum-scale stress depends upon: the imposed strain rate; the subcontinuum scale, material rheology of sea ice; the chosen configuration of sea ice floes and leads; and a prescribed rule for determining the motion of the floes in response to the continuum-scale strain-rate. We calculated plastic yield curves and flow rules associated with subcontinuum scale, material sea ice rheologies with elliptic, linear and modified Coulombic elliptic plastic yield curves, and with square, diamond and irregular, convex polygon-shaped floes. For the case of a tiling of square floes, only for particular orientations of the leads have the principal axes of strain rate and calculated continuum-scale sea ice stress aligned, and these have been investigated analytically. The ensemble average of calculated sea ice stress for square floes with uniform orientation with respect to the principal axes of strain rate yielded alignment of average stress and strain-rate principal axes and an isotropic, continuum-scale sea ice rheology. We present a lemon-shaped yield curve with normal flow rule, derived from ensemble averages of sea ice stress, suitable for direct inclusion into the current generation of sea ice models. This continuum-scale sea ice rheology directly relates the size (strength) of the continuum-scale yield curve to the material compressive strength
Clinical Use of PPARγ Ligands in Cancer
The role of PPARγ in adipocyte differentiation has fueled intense interest in the function of this steroid nuclear receptor for regulation of malignant cell growth and differentiation. Given the antiproliferative and differentiating effects of PPARγ ligands on liposarcoma cells, investigation of PPARγ expression and ligand activation in other solid tumors such as breast, colon, and prostate cancers ensued. The anticancer effects of PPARγ ligands in cell culture and rodent models of a multitude of tumor types suggest broad applicability of these agents to cancer therapy. This review focuses on the clinical use of PPARγ ligands, specifically the thiazolidinediones, for the treatment and prevention of cancer
Magnetization of Charge-ordered la(2-x)sr(x)nio(4+delta)
We report magnetization measurements on La(2-x)Sr(x)NiO(4+ delta) single
crystals, with 0 < x < 0.5. Glassy behaviour associated with the formation of
spin-charge stripes, and a separate spin-glass phase at low temperatures were
observed. We have also found a `memory effect' in the magnetic field --
temperature history, which is found to be suppressed in the low temperature
spin state of the x = 0.33 crystal.Comment: 2 pages, 2 figures. Presented at ICM2003 to appear in J. Magn. Magn.
Mat
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