Retinopathy of prematurity in Frederiksborg County 1988-1990. A prospective investigation, an update

A report is given of retinopathy of prematurity findings in a Danish county (pop. 342,000) for birth years 1988-90. Out of 12,116 liveborn infants 200 were followed with eye controls during (at least) the first 3 months. In 135 gestational age and/or birth weight were below 32 weeks/1750 g. Twenty-five had ROP stage 1-2 with uneventful regression. Out of 5 with at least stage 3 ROP 2 had spontaneous regression. Three had cryotherapy; two acquired unilateral blindness, one myopia of prematurity. As part of an ongoing prospective investigation the visual results denote progress as compared to the serious results from the preceding 6 years (6 blind children). For 1982-90 the pooled ROP blindness rate amounted to 18.7/100,000 liveborn, a frequency only to be surpassed by the neighbouring Copenhagen area. Considering correct timing of cryotherapy close observation of small premature infants is recommended. At present our screening limits are 32 weeks gestational age/1750 g birth weight.     

Cu-Ni and Ni-Cu bilayers on silicon: reduction of formation temperature and phase separation

The solid state reaction between Ni-Cu and Cu-Ni bilayers on Si(100) has been studied using X-ray diffraction, transmission electron microscopy, Auger electron spectroscopy and sheet resistance measurements. The bilayers were produced by evaporation and annealed at temperatures between 200 and 500 °C. In the Ni-Cu sequence, a strong intermixing of silicides and a 33% reduction in the formation temperature of the NiSi₂ phase compared with Ni-Si(100) was observed. When nickel was in direct contact with the silicon substrate limited intermixing and reaction of Cu was observed in the Cu-NiSi and NiSi-Si interfaces at 500 °C, due to the large grain size of the nickel silicide.     

Determining the Tensile Stress-Crack Opening Curve of Concrete by Inverse Analysis

The determination of the fundamental stress versus crack opening (σ-w) response of concrete under uniaxial tension is performed in this study through inverse analysis using data from notched beam tests. The procedure used for optimizing the parameters of the σ-w relation using the load versus crack mouth opening displacement response of the notched beam is described. Satisfactory comparisons have been obtained between the σ-w curves obtained through the inverse analysis and those directly measured in uniaxial tension tests. The use of weighting functions in the inverse analysis may be necessary when large crack widths are to be considered.     

Multi-step transformation in numerical renormalization group

We compute the temperature dependent magnetic susceptibility of the single-impurity, two-channel Anderson model with an alternative multi-step numerical renormalization-group transformation, previously applied only to the two-impurity single-channel Kondo model. Compared with the traditional transformation, the new procedure requires substantially less memory and computational time, and opens therefore perspectives for the application of the numerical renormalization-group procedure to more complex Hamiltonians.     

Congenital adrenal hyperplasia presenting as massive adrenal incidentalomas in the sixth decade of life: report of two patients with 21-hydroxylase deficiency

Divergent recommendations exist regarding the evaluation of adrenal incidentalomas. Recent data have indicated a prevalence of adrenal tumors of 71% in nonclassical congenital adrenal hyperplasia (CAH) and unmasked heterozygotes. These data expand the differential diagnosis of such incidental tumors and substantially modify the approach to their evaluation. We present two patients, female pseudohermaphrodites with the simple virilizing form of CAH and 21-hydroxylase deficiency, who functioned successfully as married phenotypic males. Both came to medical attention in the sixth decade by virtue of massive adrenal incidentalomas encountered in the evaluation of recurrent urinary tract infections. Each had a 46, XX karyotype, no palpable testes, and markedly elevated baseline levels of 17-hydroxyprogesterone (17-OH Prog) of 6086 ng/dL and 6750 ng/dL. Both responded appropriately to dexamethasone suppression with reduction of 17-OH Prog, androgens and, in the second patient, ACTH to normal or near normal levels. Histologic and autopsy examination of the first patient's tumor and computed tomographic characteristics of the second revealed a benign adenoma and myelolipoma respectively. We extend and confirm previous recommendations that CAH be included in the differential diagnosis of adrenal incidentaloma and that baseline 17-OH Prog. levels be obtained, with ACTH stimulation if necessary, to diagnose the presence of nonclassical CAH.