Juvenile arteriosclerosis: rare cause of generalized dilatative and stenosing vascular disease

In addition to generalized arteriosclerosis connective tissue disease, systemic vasculitis as well as genetic metabolic disease are described to be the cause of stenotic and aneurysmatic vessel wall alteration. Although these causes are rather unusual, they must be considered for the diagnosis of a generalized vascular disease with arterial occlusion as well as aneurysm formation to determine the appropriate procedure for the individual. Whereas operative treatment should be avoided as far as possible for patients with Beh?et's disease or Marfan syndrome, it is rather indicated for any kind of juvenile arteriosclerosis with arterial stenosis as well as dilatation. In this way the patient described in the following could be treated successfully by operation even though the cause of the juvenile arteriosclerosis was inexplicable, and in addition to local complications also the threatening rupture of the aneurysm could be controlled.     

Giant linear polarization of photoluminescence in type-II ZnSe/BeTe superlattices

The photoluminescence spectra of type-II ZnSe/BeTe superlattices are investigated. Giant linear polarization of the luminescence is observed with unpolarized excitation in the spatially indirect exciton region. The effect is interpreted in a model of the general optical anisotropy of heterostructures with no common atom at the interfaces. Fiz. Tekh. Poluprovodn. 33, 1093–1095 (September 1999)     

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.     

Depositional response of a headwater stream to channelization,East Central Illinois,USA

Channelization typically modifies the energy regime and sediment transport capacity of rivers, triggering morphologic adjustments. Most past studies of channelization have focused on erosional responses involving channel incision and widening. Depositional adjustments to channelization, although noted in previous work, have not been documented in detail. This study investigates the depositional response of the Spoon River, a headwater agricultural stream in Illinois, USA, to channelization. Historical aerial and ground‐based photography show that channelization of the Spoon River in the early 20th century produced a wide, deep trapezoidal drainage channel. Following this channelization, unvegetated alternate and mid‐channel bars developed on the bottom of the ditch. Sedimentological analysis of bar stratigraphy indicates that the bars grew through vertical accretion of horizontal sheets of sand‐and‐gravel bedload and organic‐rich drapes of fine‐grained suspended load. The horizontal sheets of sand and gravel are consistent with the braided conditions shown on historical photographs. Late‐stage bar growth appears to have been dominated by progressive overbank deposition of suspended load as indicated by the presence of a thick, fine‐grained organic‐rich A horizon immediately below the surface of each bar. The development of a soil layer also suggests that the bars are stable—an inference supported by the thick grass cover on the bar surfaces. The net result of the depositional response is the formation of a meandering channel flanked by a discontinuous floodplain on the bottom of the ditch. The construction of a wide ditch relative to original stream size is a key factor promoting a depositional response to channelization. Allowing or actively promoting floodplain elements to form in overwidened ditches may be a viable management option for improving the environmental quality of channelized agricultural streams. The Spoon River has a diverse fish community compared to channelized streams in East Central Illinois that lack a meandering low‐flow channel. This morphological configuration apparently enhances geomorphological and ecological variability while sustaining the drainage function of the ditch. Copyright © 2003 John Wiley & Sons, Ltd.     

Strength of functionally designed cellular cemented carbides produced by coextrusion

In an effort to improve the wear characteristics of petroleum drill bit inserts, a series of cemented carbide materials with a functionally designed cellular (FDC) architecture were fabricated by a coextrusion process. The FDC architecture characterized in this study was comprised of cemented carbide cells surrounded by a ductile cobalt cell boundary. Property evaluation employed transverse rupture strength (TRS) testing to characterize their mechanical behavior. It was determined that the presence of Co_{2 + x} W_{4 − x} C in the material greatly affected the bonding of the cell to the cell boundary and therefore the strength of the material. Fractography of the FDC materials supported the hypothesis that the interface between the cell and cell boundary was affected by the Co_{2 + x} W_{4 − x} C phase and the consequential reduction in cobalt content of the cell.