Limited clinical utility of midtrimester fetal morphometric percentile rankings in screening for birth weight abnormalities

OBJECTIVE: Our purpose was to determine whether midtrimester fetal ultrasonographic morphometric percentile rankings are sensitive screening tests for preterm labor or birth weight abnormalities. STUDY DESIGN: Stepwise multiple regression and chi 2 analysis were used to identify midtrimester fetal measurements predicting birth weight and gestational age. Receiver-operator characteristics curves were used to evaluate abdominal circumference percentiles as a test for large-for-gestational-age and small-for-gestational-age infants. RESULTS: Extremes in abdominal circumference and head measurement percentiles were associated with large- and small-for gestational-age infants but not with preterm delivery. Abdominal circumference predicted birth weight in regression analysis; however, receiver-operator characteristic curves showed abdominal circumference percentiles to be poor screening tests for large- or small-for-gestational-age infants. The positive predictive value of 10th and 90th abdominal circumference percentiles for small- and large-for-gestational-age infants was < 20%. CONCLUSION: Midtrimester percentile rankings offer no clear benefit in targeting fetuses with potential birth weight abnormalities or risk of preterm delivery and may provide clinically misleading information.     

Scientific Cooperation Between East and West in Difficult Times

The development of physics in Russia and the Soviet Union since the beginning of this century is briefly discussed. The relations between Eastern and Western physicists and especially the isolation during the cold war are outlined, mainly on the basis of personal experience. Finally the dramatic situation that arose after the collapse of the Soviet Union is treated and efforts to help science in the FSU (Former Soviet Union) to survive.     

BeCdSe: A new material for the active region in devices operating in the blue-green region of the spectrum

Submonolayer cyclic epitaxy was used for the first time to obtain a bulk layer of BeCdSe solid solution 100 nm thick with a Be content close to 46%, which corresponded to the composition lattice-matched to the GaAs substrate. In addition, low-temperature lasing at a wavelength of 460 nm with a threshold power density of about 40 kW/cm² in a structure with multiple ZnSe/BeCdSe quantum wells was also attained for the first time. The band-bending parameter in the BeCdSe solid solutions was estimated at 4.5 eV.     

Somatosensory evoked potentials: a simple neurophysiological monitoring technique in supra-aortal balloon test occlusions

The aim of this study was to evaluate somatosensory evoked potentials (SEP) as a simple neurophysiological monitoring method in supra-aortal balloon test occlusions (BTO). The 13 patients examined had carcinoma of the larynx (n = 6), nasopharyngeal malignancy (n = 3), sphenoid meningioma (n = 2), mycotic aneurysm (n = 1), and a tumor of the carotid body (n = 1). Transfemoral balloon occlusion of the internal carotid artery was maintained for 30 min and monitored both clinically and by SEP. None of the 13 patients showed neurological deficits or pathological changes in the SEP. No thromboembolic complications occurred during BTO. In 11 cases the cervical vessels could be spared or reconstructed during surgery. No neurological symptoms occurred during the clinical follow-up. One patient died the day after BTO due to cardiac arrest. Neurophysiological monitoring of preoperative BTO using SEP is a technically simple method. A similar method has been shown to have a high sensitivity and reliability in carotid surgery.