Radiative properties of numerically generated fractal soot aggregates of different fractal dimensions were studied using the numerically accurate generalized Mie-solution method (GMM) and the Rayleigh-Debye-Gans (RDG) approximate theory. Fractal aggregates of identical prefactor but different fractal dimensions, namely, 1.4, 1.78, and 2.1, were generated numerically using a tunable algorithm of cluster-cluster aggregation for aggregates containing up to 800 primary particles. Radiative properties of these aggregates were calculated at a wavelength of 532 nm assuming a soot refractive index of 1.6 + 0.6i. Four commonly used structure factors in the RDG approximation were used to investigate the effect of structure factor on the differential and total scattering cross-sections and the asymmetry factor. The differential and total scattering properties calculated using the RDG approximation become increasingly sensitive to the structure factor with increasing the fractal dimension. Primary particle interactions are the fundamental mechanism for the aggregate absorption enhancement for small aggregates and the shielding effect for larger aggregates. The extent of these two competing factors is dependent on the fractal dimension and aggregate size. RDG reasonably predicts the effect of fractal dimension on the scattering properties, but fails to account for the effect of aggregation or fractal morphology on the absorption property of fractal soot aggregates, though the error is in general less than 15%.

Brief communications 1207 ble aortic arch, type B interruption of the left arch, coarctation, aberrant subclavian arteries, and associated multiple right-sided facial and upper limb superficial and deep hemangiomas.Clinical summaries PATIENT 1. A baby girl was born by elective cesarean birth for cephalopelvic disproportion at term in August 1984 and required ventilatory assistance for 6 days for hyaline membrane disease. During this period she was found to have a continuous cardiac murmur and heart failure. There was no history of congenital heart disease in the family, which included one healthy sibling. Multiple capillary hemangiomas were noted over the right side of her face, shoulder, and arm and a deeper hemangioma was present on the back of her neck.Congenital aortic lesions are occasionally associated with clinical syndromes. Recognition of these syndromes is important in aiding clinical diagnosis and accurate surgical management. We describe the case histories of 2 children who appear to have a new vascular syndrome comprising right dominant dou-

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attacking the transplanted liver respectively. However, even with multi-modal therapy, the patient's condition worsened indicated by a rising MELD (model of end-stage liver disease) score and bilirubin concentration to 8 mg/dL. Discussion: We present a unique case of acute (antibody-mediated) rejection progressing to chronic rejection in a LDLT patient following pregnancy due to sensitization to donor HLA DQ6. Consistent posttransplant HLA antibody testing should be a consideration for LDLT patients for early detection and treatment of DSA before memory B-cell production allows rejection to become chronic. Testing is especially important for monitoring female patients with LDLTs from spouse due to risk of blood exposure during pregnancy.

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