487 research outputs found
An Integral Kernel for Weakly Pseudoconvex Domains
A new explicit construction of Cauchy-Fantappi\'e kernels is introduced for
an arbitrary weakly pseudoconvex domain with smooth boundary. While not
holomorphic in the parameter, the new kernel reflects the complex geometry and
the Levi form of the boundary. Some estimates are obtained for the
corresponding integral operator, which provide evidence that this kernel and
related constructions give useful new tools for complex analysis on this
general class of domains
Measuring velocity of sound with nuclear resonant inelastic x-ray scattering
Nuclear resonant inelastic x-ray scattering is used to measure the projected
partial phonon density of states of materials. A relationship is derived
between the low-energy part of this frequency distribution function and the
sound velocity of materials. Our derivation is valid for harmonic solids with
Debye-like low-frequency dynamics. This method of sound velocity determination
is applied to elemental, composite, and impurity samples which are
representative of a wide variety of both crystalline and noncrystalline
materials. Advantages and limitations of this method are elucidated
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Third Annual Report: 2006 Pre-Construction Eelgrass Monitoring and Propagation for King County Outfall Mitigation
King County proposes to build a new sewer outfall discharging to Puget Sound near Point Wells, Washington. Construction is scheduled for 2008. The Point Wells site was selected to minimize effects on the nearshore marine environment, but unavoidable impacts to eelgrass (Zostera marina) beds are anticipated during construction. To mitigate for these impacts and prepare for post-construction restoration, King County began implementation of a multi-year eelgrass monitoring and restoration program in 2004, with the primary goal of returning intertidal and shallow subtidal habitat and eelgrass to pre-construction conditions. Major program elements are a) pre-construction monitoring, i.e., documenting initial eelgrass conditions and degree of fluctuation over 5 years prior to construction, b) eelgrass transplanting, including harvesting, offsite propagating and stockpiling of local plantstock, and post-construction planting, and c) post-construction monitoring. The program is detailed in the Eelgrass Restoration and Biological Resources Implementation Workplan (King County 2006). This report describes calendar year 2006 pre-construction activities conducted by Pacific Northwest National Laboratory (PNNL) in support of King County. Activities included continued propagation of eelgrass shoots and monitoring of the experimental harvest plots in the marine outfall corridor area to evaluate recovery rates relative to harvest rates. Approximately 1500 additional shoots were harvested from the marine outfall corridor in August 2006 to supplement the plants in the propagation tank at the PNNL Marine Sciences Laboratory in Sequim, Washington, bringing the total number of shoots to 4732. Eelgrass densities were monitored in the five experimental harvest plots established in the marine outfall corridor. Changes in eelgrass density were evaluated in year-to-year comparisons with initial harvest rates. Net eelgrass density decreased from 2004 post-harvest to 2006 in all plots, despite density increases observed in 2005 in some plots and at some harvest rates. Eelgrass densities within individual subplots were highly variable from year to year, and the change in density in any interannual period did not correlate to the initial 2004 harvest rate. Continued monitoring should help project managers determine an optimum harvest rate that supports rapid recovery of donor eelgrass beds
Pressure Dependence of the Elastic Moduli in Aluminum Rich Al-Li Compounds
I have carried out numerical first principles calculations of the pressure
dependence of the elastic moduli for several ordered structures in the
Aluminum-Lithium system, specifically FCC Al, FCC and BCC Li, L1_2 Al_3Li, and
an ordered FCC Al_7Li supercell. The calculations were performed using the full
potential linear augmented plane wave method (LAPW) to calculate the total
energy as a function of strain, after which the data was fit to a polynomial
function of the strain to determine the modulus. A procedure for estimating the
errors in this process is also given. The predicted equilibrium lattice
parameters are slightly smaller than found experimentally, consistent with
other LDA calculations. The computed elastic moduli are within approximately
10% of the experimentally measured moduli, provided the calculations are
carried out at the experimental lattice constant. The LDA equilibrium shear
modulus C11-C12 increases from 59.3 GPa in Al, to 76.0 GPa in Al_7Li, to 106.2
GPa in Al_3Li. The modulus C_44 increases from 38.4 GPa in Al to 46.1 GPa in
Al_7Li, then falls to 40.7 GPa in Al_3Li. All of the calculated elastic moduli
increase with pressure with the exception of BCC Li, which becomes elastically
unstable at about 2 GPa, where C_11-C_12 vanishes.Comment: 17 pages (REVTEX) + 7 postscript figure
Interacting particles at a metal-insulator transition
We study the influence of many-particle interaction in a system which, in the
single particle case, exhibits a metal-insulator transition induced by a finite
amount of onsite pontential fluctuations. Thereby, we consider the problem of
interacting particles in the one-dimensional quasiperiodic Aubry-Andre chain.
We employ the density-matrix renormalization scheme to investigate the finite
particle density situation. In the case of incommensurate densities, the
expected transition from the single-particle analysis is reproduced. Generally
speaking, interaction does not alter the incommensurate transition. For
commensurate densities, we map out the entire phase diagram and find that the
transition into a metallic state occurs for attractive interactions and
infinite small fluctuations -- in contrast to the case of incommensurate
densities. Our results for commensurate densities also show agreement with a
recent analytic renormalization group approach.Comment: 8 pages, 8 figures The original paper was splitted and rewritten.
This is the published version of the DMRG part of the original pape
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Hematopoietic Cell Transplantation in Patients With Primary Immune Regulatory Disorders (PIRD): A Primary Immune Deficiency Treatment Consortium (PIDTC) Survey.
Primary Immune Regulatory Disorders (PIRD) are an expanding group of diseases caused by gene defects in several different immune pathways, such as regulatory T cell function. Patients with PIRD develop clinical manifestations associated with diminished and exaggerated immune responses. Management of these patients is complicated; oftentimes immunosuppressive therapies are insufficient, and patients may require hematopoietic cell transplant (HCT) for treatment. Analysis of HCT data in PIRD patients have previously focused on a single gene defect. This study surveyed transplanted patients with a phenotypic clinical picture consistent with PIRD treated in 33 Primary Immune Deficiency Treatment Consortium centers and European centers. Our data showed that PIRD patients often had immunodeficient and autoimmune features affecting multiple organ systems. Transplantation resulted in resolution of disease manifestations in more than half of the patients with an overall 5-years survival of 67%. This study, the first to encompass disorders across the PIRD spectrum, highlights the need for further research in PIRD management
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