8,888 research outputs found
Dehn twists and Lagrangian spherical manifolds
Abstract
We study Dehn twists along Lagrangian submanifolds that are finite free quotients of spheres. We describe the induced auto-equivalences to the derived Fukaya category and explain their relations to mirror symmetry.National Science Foundation under agreement No. DMS-
1128155, EPSRC (Establish Career Fellowship EP/N01815X/1), Simons Collaboration Grant 52442
A study of operating reserve procurance in power markets with application of insurance theory: contract-based vs pool-based approaches
In the power markets, the ancillary services are treated as special commodities. Operating reserve is an important commodity in the category of ancillary services, which supports the system reliability against unexpected generator outages. In this paper, we study the procurance of operating reserve via two approaches, i.e. contract-based model and pool-based model. In order to guarantee the availability of reserved capacity and reduce the loss of consumer at generator forced outages, insurance policy is applied. Decentralized optimal decision is adopted. After presenting the math models of the two approaches, it is proven that the pool-based approach is more cost-effective and should be adopted in the deregulated power markets.published_or_final_versio
Interaction of wave with a body submerged below an ice sheet with multiple arbitrarily spaced cracks
The problem of wave interaction with a body submerged below an ice sheet with multiple arbitrarily spaced cracks is considered, based on the linearized velocity potential theory together with the boundary element method. The ice sheet is modeled as a thin elastic plate with uniform properties, and zero bending moment and shear force conditions are enforced at the cracks. The Green function satisfying all the boundary conditions including those at cracks, apart from that on the body surface, is derived and is expressed in an explicit integral form. The boundary integral equation for the velocity potential is constructed with an unknown source distribution over the body surface only. The wave/crack interaction problem without the body is first solved directly without the need for source. The convergence and comparison studies are undertaken to show the accuracy and reliability of the solution procedure. Detailed numerical results through the hydrodynamic coefficients and wave exciting forces are provided for a body submerged below double cracks and an array of cracks. Some unique features are observed, and their mechanisms are analyzed
Energy bands and Landau levels of ultracold fermions in the bilayer honeycomb optical lattice
We investigate the spectrum and eigenstates of ultracold fermionic atoms in
the bilayer honeycomb optical lattice. In the low energy approximation, the
dispersion relation has parabolic form and the quasiparticles are chiral. In
the presence of the effective magnetic field, which is created for the system
with optical means, the energy spectrum shows an unconventional Landau level
structure. Furthermore, the experimental detection of the spectrum is proposed
with the Bragg scattering techniques.Comment: To appear in Journal of Modern Optic
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Tumescent Injections in Subcutaneous Pig Tissue Disperse Fluids Volumetrically and Maintain Elevated Local Concentrations of Additives for Several Hours, Suggesting a Treatment for Drug Resistant Wounds.
PurposeBolus injection of fluid into subcutaneous tissue results in accumulation of fluid at the injection site. The fluid does not form a pool. Rather, the injection pressure forces the interstitial matrix to expand to accommodate the excess fluid in its volume, and the fluid becomes bound similar to that in a hydrogel. We seek to understand the properties and dynamics of externally tumesced (swollen) subcutaneous tissue as a first step in assessing whether tumescent antibiotic injections into wounds may provide a novel method of treatment.MethodsSubcutaneous injections of saline are performed in live and dead pigs and the physical properties (volume, expansion ratio, residence time, apparent diffusion constant) of the resulting fluid deposits are observed with diffusion-weighted magnetic resonance imaging, computed tomography, and 3D scanning.ResultsSubcutaneous tissue can expand to a few times its initial volume to accommodate the injected fluid, which is dispersed thoroughly throughout the tumescent volume. The fluid spreads to peripheral unexpanded regions over the course of a few minutes, after which it remains in place for several hours. Eventually the circulation absorbs the excess fluid and the tissue returns to its original state.ConclusionsGiven the evidence for dense fluid dispersal and several-hour residence time, a procedure is proposed whereby tumescent antibiotic injections are used to treat drug-resistant skin infections and chronic wounds that extend into the subcutaneous tissue. The procedure has the potential to effectively treat otherwise untreatable wounds by keeping drug concentrations above minimum inhibitory levels for extended lengths of time
Identification of differentially expressed genes in seeds of two Brassica napus mutant lines with different oleic acid content
The regulation of seed oleic acid synthesis in rapeseed is largely unknown. In this study, gene expression pattern during seed development between two Brassica napus mutants was compared. Using immature seeds 27 days after pollination, differentially expressed cDNA clones were identified bysubtractive suppression hybridization (SSH). A total of 480 cDNA clones corresponding to 88 genes were found up-regulated and 18 genes down-regulated in seeds with high oleic acid content. Most ofthe differentially expressed genes are related to metabolism and regulation. The possible role of these genes in seeds was discussed. Further analysis of the function of these genes may provide novel targets for manipulation of fatty acid composition in rapeseed
Methods in angle-resolved photoelectron diffraction: Slab method versus separable propagator cluster approach
We have compared multiple-scattering results of angle-resolved photoelectron diffraction spectra between the exact slab method and the separable propagator perturbation cluster method. In the slab method, the source wave and multiple scattering within strongly scattering layers are expanded in spherical waves while the scattering among different layers is expressed in plane waves. The transformation between spherical waves and plane waves is done exactly. The plane waves are then matched across the solid-vacuum interface to a single outgoing plane wave in the detector's direction. The slab is infinitely extended parallel to the surface. Normal to the surface, enough layers are included to ensure convergence of the calculated intensity. The separable propagator perturbation approach uses two approximations; (i) A separable representation of the Green's-function propagator and (ii) a perturbation expansion of multiple-scattering terms. The cluster size is finite, typically containing 50 atoms or less. Results of this study show that using a cluster of 148 atoms, the largest cluster used to date, the cluster size is still too small for the cluster results on Ni(001) to converge with those of the slab method. Ideas to improve the perturbation expansion cluster method are discussed.published_or_final_versio
A decentralized approach for operating reserve procurement
In power markets, operating reserve procurement is usually centrally handled according to certain reliability rules and aiming at minimization of total cost for reserve procurement. In this approach, there are no customers' choices, no incentives for ISO to minimize the total cost or for reserve suppliers to commit promised reserve capacity. It may leads to severe inefficiency. In this paper, we propose a decentralized approach for operating reserve procurement and in the meantime, to discover the market price for it. In the approach, each participant selects the optimal decision to maximize his or her own interests. Insurance theory is applied; which allows consumers to transfer their risk for financial loss of outage to the ISO, and induces incentive for the ISO to manage the entire amount of reserve capacity in an efficient manner. A penalty system is introduced, which improves the liability for the genco to provide operating reserve. Detailed math model and solution procedure are presented. It is also shown that with properly defined reserve market's structure, the decentralized approach can yield same optimal solution as its centralized counterpart. Numerical example results illustrate the effectiveness of the suggested approach.published_or_final_versio
Cardiovascular Disease in Diabetic Nephropathy Patients: Cell Adhesion Molecules as Potential Markers?
Cardiovascular disease is a major complication of diabetes mellitus, especially for patients with diabetic nephropathy. The underlying factor or pathogenic mechanism that links diabetic nephropathy with cardiovascular disease is not known. The endothelial cell adhesion molecules, intercellular adhesion molecule-1 or vascular cell adhesion molecule-1, play a crucial role in the initiation of atherosclerosis. Levels of both cell adhesion molecules are raised by the diabetic and kidney disease states. This review focuses on these important cell adhesion molecules and their role in the pathogenesis of cardiovascular disease in diabetes and diabetic nephropathy
Comparing the sensitivity of ionization chamber array to film and point dose measurement for IMRT delivery errors
Abstract no. 10625Therapy General Poster Discussion: SUâFFâTâ226PURPOSE: To compare the sensitivity of 2D ion chamber array, film dosimetry and point dose measurement for detecting IMRT delivery errors. METHOD AND MATERIALS: 2 types of IMRT delivery errors were considered. First type involved adding 1 mm systematic error to 1 bank of the MLC leaves, resulting in a dose discrepancy of â„ 5%. The second type involved âundeliverable intensity patternsâ, resulting from improper use of smoothness constraint during optimization. 4 and 2 plans were studied for type 1 and âŠpostprin
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