661 research outputs found
The complex Jacobi iterative method for three-dimensional wide-angle beam propagation (vol 16, pg 17021, 2008)
An erratum is presented to correct the definition of coefficient xi* in Eq. (12) in our paper
Trefftz Difference Schemes on Irregular Stencils
The recently developed Flexible Local Approximation MEthod (FLAME) produces
accurate difference schemes by replacing the usual Taylor expansion with
Trefftz functions -- local solutions of the underlying differential equation.
This paper advances and casts in a general form a significant modification of
FLAME proposed recently by Pinheiro & Webb: a least-squares fit instead of the
exact match of the approximate solution at the stencil nodes. As a consequence
of that, FLAME schemes can now be generated on irregular stencils with the
number of nodes substantially greater than the number of approximating
functions. The accuracy of the method is preserved but its robustness is
improved. For demonstration, the paper presents a number of numerical examples
in 2D and 3D: electrostatic (magnetostatic) particle interactions, scattering
of electromagnetic (acoustic) waves, and wave propagation in a photonic
crystal. The examples explore the role of the grid and stencil size, of the
number of approximating functions, and of the irregularity of the stencils.Comment: 28 pages, 12 figures; to be published in J Comp Phy
Speaking of trade: Key issues for agriculture
This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu
TGF-ÎČâdependent CD103 expression by CD8+ T cells promotes selective destruction of the host intestinal epithelium during graft-versus-host disease
Destruction of the host intestinal epithelium by donor effector T cell populations is a hallmark of graft-versus-host disease (GVHD), but the underlying mechanisms remain obscure. We demonstrate that CD8+ T cells expressing CD103, an integrin conferring specificity for the epithelial ligand E-cadherin, play a critical role in this process. A TCR transgenic GVHD model was used to demonstrate that CD103 is selectively expressed by host-specific CD8+ T cell effector populations (CD8 effectors) that accumulate in the host intestinal epithelium during GVHD. Although host-specific CD8 effectors infiltrated a wide range of host compartments, only those infiltrating the intestinal epithelium expressed CD103. Host-specific CD8 effectors expressing a TGF-ÎČ dominant negative type II receptor were defective in CD103 expression on entry into the intestinal epithelium, which indicates local TGF-ÎČ activity as a critical regulating factor. Host-specific CD8 effectors deficient in CD103 expression successfully migrated into the host intestinal epithelium but were retained at this site much less efficiently than wild-type host-specific CD8 effectors. The relevance of these events to GVHD pathogenesis is supported by the finding that CD103-deficient CD8+ T cells were strikingly defective in transferring intestinal GVHD pathology and mortality. Collectively, these data document a pivotal role for TGF-ÎČâdependent CD103 expression in dictating the gut tropism, and hence the destructive potential, of CD8+ T cells during GVHD pathogenesis
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High-Power Single Mode Operation of Hybrid Ion-Implanted/Selectively-Oxidized VCSELs
Design, fabrication, and performance of infrared and visible vertical cavity surface emitting lasersâ,
Abstract-This paper discusses the issues involving the design and fabrication of vertical-cavity surface-emitting lasers (VCSEL's). A review of the basic experimental structures is given, with emphasis on recent developments in distributed Bragg reflectors, gain media, as well as current and optical confinement techniques. The paper describes present VCSEL performance, in particular, those involving selective oxidation and visible wavelength operation
Exposure to aflatoxin and fumonisin in children at risk for growth impairment in rural Tanzania
Growth impairment is a major public health issue for children in Tanzania. The question remains as to whether dietary mycotoxins play a role in compromising children's growth. We examined children's exposures to dietary aflatoxin and fumonisin and potential impacts on growth in 114 children under 36âŻmonths of age in Haydom, Tanzania. Plasma samples collected from the children at 24âŻmonths of age (NâŻ=âŻ60) were analyzed for aflatoxin Bâ-lysine (AFBâ-lys) adducts, and urine samples collected between 24 and 36âŻmonths of age (NâŻ=âŻ94) were analyzed for urinary fumonisin Bâ (UFBâ). Anthropometric, socioeconomic, and nutritional parameters were measured and growth parameter z-scores were calculated for each child. Seventy-two percent of the children had detectable levels of AFBâ-lys, with a mean level of 5.1 (95% CI: 3.5, 6.6) pg/mg albumin; and 80% had detectable levels of UFBâ, with a mean of 1.3 (95% CI: 0.8, 1.8) ng/ml. This cohort had a 75% stunting rate [height-for-age z-scores (HAZ)âŻ<âŻâ2] for children at 36âŻmonths. No associations were found between aflatoxin exposures and growth impairment as measured by stunting, underweight [weight-for-age z-scores (WAZ)âŻ<âŻâ2], or wasting [weight-for-height z-scores (WHZ)âŻ<âŻâ2]. However, fumonisin exposure was negatively associated with underweight (with non-detectable samples included, pâŻ=âŻ0.0285; non-detectable samples excluded, pâŻ=âŻ0.005) in this cohort of children. Relatively low aflatoxin exposure at 24âŻmonths was not linked with growth impairment, while fumonisin exposure at 24â36âŻmonths based on the UFBâ biomarkers may contribute to the high growth impairment rate among children of Haydom, Tanzania; which may be associated with their breast feeding and weaning practices
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