Eigenvalue Bounds for Perturbations of Schrodinger Operators and Jacobi Matrices With Regular Ground States

We prove general comparison theorems for eigenvalues of perturbed Schrodinger operators that allow proof of Lieb--Thirring bounds for suitable non-free Schrodinger operators and Jacobi matrices.Comment: 11 page

CORE and the Haldane Conjecture

The Contractor Renormalization group formalism (CORE) is a real-space renormalization group method which is the Hamiltonian analogue of the Wilson exact renormalization group equations. In an earlier paper\cite{QGAF} I showed that the Contractor Renormalization group (CORE) method could be used to map a theory of free quarks, and quarks interacting with gluons, into a generalized frustrated Heisenberg antiferromagnet (HAF) and proposed using CORE methods to study these theories. Since generalizations of HAF's exhibit all sorts of subtle behavior which, from a continuum point of view, are related to topological properties of the theory, it is important to know that CORE can be used to extract this physics. In this paper I show that despite the folklore which asserts that all real-space renormalization group schemes are necessarily inaccurate, simple Contractor Renormalization group (CORE) computations can give highly accurate results even if one only keeps a small number of states per block and a few terms in the cluster expansion. In addition I argue that even very simple CORE computations give a much better qualitative understanding of the physics than naive renormalization group methods. In particular I show that the simplest CORE computation yields a first principles understanding of how the famous Haldane conjecture works for the case of the spin-1/2 and spin-1 HAF.Comment: 36 pages, 4 figures, 5 tables, latex; extensive additions to conten

Bifurcation and stability for Nonlinear Schroedinger equations with double well potential in the semiclassical limit

We consider the stationary solutions for a class of Schroedinger equations with a symmetric double-well potential and a nonlinear perturbation. Here, in the semiclassical limit we prove that the reduction to a finite-mode approximation give the stationary solutions, up to an exponentially small term, and that symmetry-breaking bifurcation occurs at a given value for the strength of the nonlinear term. The kind of bifurcation picture only depends on the non-linearity power. We then discuss the stability/instability properties of each branch of the stationary solutions. Finally, we consider an explicit one-dimensional toy model where the double well potential is given by means of a couple of attractive Dirac's delta pointwise interactions.Comment: 46 pages, 4 figure

Recurrent Variational Approach to the Two-Leg Hubbard Ladder

We applied the Recurrent Variational Approach to the two-leg Hubbard ladder. At half-filling, our variational Ansatz was a generalization of the resonating valence bond state. At finite doping, hole pairs were allowed to move in the resonating valence bond background. The results obtained by the Recurrent Variational Approach were compared with results from Density Matrix Renormalization Group.Comment: 10 pages, 14 Postscript figure

Cyclosporine absorption profiles in pediatric kidney and liver transplant patients

Cyclosporine absorption profiling uses either the area under the concentration curve in the first 4 h post dose, AUC(0–4), or the concentration 2 h post dose (C2) to optimize immunosuppression in adult kidney and liver transplantation. We characterized C2 versus AUC(0–4) relationships over time after transplant and across transplant indications in 56 pediatric transplant patients. There were 36 kidney transplant patients aged 9.7±3.9 years. Nineteen of these patients were studied in the de novo period on day 7 post transplant and 17 in the maintenance phase more than 1 year post transplant. In addition, 20 liver transplant patients aged 8.9±4.2 years were studied in the maintenance phase. All patients had five blood samples collected over the 12-h dose interval that were analyzed by validated assay methods at a central laboratory. Pediatric C2 values were 1,463±658 ng/ml for de novo kidney, 954±322 ng/ml for maintenance kidney, and 619±339 ng/ml for maintenance liver transplant patients. C2 was a strong predictor of AUC(0–4) in all three pediatric groups, with coefficients of determination ( r 2 ) ranging from 0.861 to 0.936. Although data were limited from the de novo period, the C2 versus AUC(0–4) regression was consistent over time after transplant and between transplant indications, with a regression slope of 2.50 in de novo kidney, 2.54 in maintenance kidney, and 2.76 in maintenance liver transplant recipients. These slopes were also comparable to that in adult maintenance kidney transplant patients (2.60). In conclusion, C2 versus AUC(0–4) relationships demonstrated consistency over time (de novo vs. maintenance phase), between transplant indications (kidney vs. liver), and across age groups (pediatric vs. adult patients). Average C2 values achieved with current pediatric cyclosporine dosing practices cluster around the target C2 ranges recommended for adults.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47821/1/467_2003_Article_1260.pd

Effect of Loading Method on a Peptide Substrate Reporter in Intact Cells [post-print]

Studies of live cells often require loading of exogenous molecules through the cell membrane; however, effects of loading method on experimental results are poorly understood. Therefore, in this work, we compared three methods for loading a fluorescently labeled peptide into cells of the model organism Dictyostelium discoideum. We optimized loading by pinocytosis, electroporation, and myristoylation to maximize cell viability and characterized loading efficiency, localization, and uniformity. We also determined how the loading method affected measurements of enzyme activity on the peptide substrate reporter using capillary electrophoresis. Loading method had a strong effect on the stability and phosphorylation of the peptide. The half-life of the intact peptide in cells was 19 ± 2, 53 ± 15, and 12 ± 1 min, for pinocytosis, electroporation, and myristoylation, respectively. The peptide was phosphorylated only in cells loaded by electroporation. Fluorescence microscopy suggested that the differences between methods were likely due to differences in peptide localization

FAPRI 2000 U.S. Agricultural Outlook

Crop Production/Industries, Livestock Production/Industries,

FAPRI 2000 World Agricultural Outlook

The Food and Agricultural Policy Research Institute (FAPRI) prepares a preliminary agricultural outlook on world agricultural production, consumption, and trade every fall. This is followed by an outside review, re-evaluation of projections, and completion of the final baseline in January. The FAPRI 2000 World Agricultural Outlook presents these final projections for world agricultural markets. A companion volume, the FAPRI 2000 U.S. Agricultural Outlook, presents the U.S. component of the baseline. FAPRI projections assume average weather patterns worldwide, existing policy, and policy commitments under current trade agreements. FAPRI projections do not include conjectures on potential policy changes, such as those resulting from the likely eastward enlargement of the European Union (EU). The baseline predicts recovery of world agricultural production, consumption, and trade, but with remaining price weakness for crops. Stock-to-use ratios in world crop markets remain high despite the strong recovery of Asian and Latin American economies. Above-average yields kept world production high relative to demand in 1999. In contrast, pork and beef prices are increasing significantly above their 1999 level. The physical volume of U.S. agricultural exports is projected to reverse the downward trend of fiscal year (FY) 1999, whereas the value of agricultural exports continue to decline for one more year before recovering because of low crop prices in 2000/01. World crop trade is projected to increase by 55 million metric tons (mmt) in the coming decade, with the United States capturing 49 percent of the expanded market, but still unable to increase its market share by a large percentage. Following this expansion of the market, grain prices increase by 35 percent in the projection period, but still stay well below the peak of 1995/96. The increase in world crop trade reflects the increasing specialization occurring in world agriculture. Increased market access and land scarcity in many Asian economies induce them to import grains and oilseeds to meet their feed demand. Developing Asia remains the fastest growing market for corn in the next decade. With implementation of Agenda 2000 reforms, the EU will reduce its wheat domestic price relative to the world price and will export wheat without subsidies after 2004, constraining gains in market shares for the United States. EU barley exports will expand significantly in the coming years but are likely to be constrained by General Agreement on Tariffs and Trade (GATT) commitments on export subsidies after 2004. World meat trade will increase by 31 percent over the next decade. The United States has become a competitive producer and exporter of meat products. In the coming decade, the United States will experience the largest meat export growth rates among major exporters of beef, pork, and broilers. U.S. exporters capture more than 70 percent of the growth in trade, increasing their share of the combined meat markets from 23 percent in 1999 to 37 percent in 2009. Meat imports are recovering and expanding rapidly in Japan, South Korea, and Taiwan. In Japan, the share of imports in consumption increases from 38 percent in the 1990s to 49 percent at the end of the next decade. Taiwan meat imports will triple from 1990-1999 levels to 2000-2009 levels, driven by imports of beef, non muscle pork products, and the opening of the poultry market. Recovery of Asian food demand will prompt dairy prices to grow by about 1 percent per year over the next decade. Total milk production is projected to increase, with particularly strong growth in the United States, Mexico, Argentina, and Brazil. Most of the growth occurs through yield increases. Per capita cheese consumption is expected to grow by 1 to 2 percent a year in most countries.Crop Production/Industries, Livestock Production/Industries,

FAPRI 2001 U.S. and World Agricultural Outlook

Crop Production/Industries, Livestock Production/Industries,