12,343 research outputs found
Contribution of thermal noise to the line width of Josephson radiation from superconducting point contacts
Contribution of thermal noise to line width of Josephson radiation from superconducting point contact
Rethinking Prenatal Screening for Anomalies of Placental and Umbilical Cord Implantation
The most common anomalies of implantation of the placenta and umbilical cord include placenta previa, placenta accreta spectrum, and vasa previa, and are associated with considerable perinatal and maternal morbidity and mortality. There is moderate quality evidence that prenatal diagnosis of these conditions improves perinatal outcomes and the performance of ultrasound imaging in diagnosing them is considered excellent. The epidemiology of placenta previa is well known, and it is standard clinical practice to assess placental location at the routine screening second-trimester detailed fetal anatomy ultrasound examination. In contrast, the prevalence of placenta accreta spectrum and vasa previa in the general population is more difficult to evaluate because detailed confirmatory histopathologic data are not available in most studies. The sensitivity and specificity of ultrasonography for the diagnosis of these anomalies is also difficult to assess. Recent epidemiologic studies show an increase in the incidence of placental and umbilical cord implantation anomalies, which may be the result of increased use of assisted reproductive technology and cesarean delivery. There is good evidence to support targeted standardized protocols for women at high risk and that screening and diagnosing placenta accreta spectrum and vasa previa should be integrated into obstetric ultrasound training programs
Creating a Learning Space in Problem-based Learning
An important aspect of PBL problems is the affordances that they hold for engaging students in discussion of important content knowledge. In this paper, I argue that one can analyze a problem in terms of a deep problem space and a broader learning space to identify the conceptual ideas for potential engagement. The problem space refers to the specific ideas and concepts that are part of the goals of the problem at hand. The learning space includes those aspects of the problem space and also includes the broader space of related conceptual ideas such as the anatomy and physiology related to a particular disorder or the pathology and clinical medicine of other disorders that might be considered as part of a differential diagnosis. This idea is tested in an exploratory analysis of a PBL tutorial conducted by Howard Barrows. The results demonstrate that much of students’ talk is focused in these related conceptual spaces and a substantial amount of the overall learning space is engaged in the group discussion. These results have implications for understanding the affordances of problems and providing another lens on how learning unfolds in a PBL problem. It also provides another means for evaluation of learning and assessment of discursive productivity in PBL groups
Research and education in management of large- scale technical programs Semiannual progress report
Research and education in management of large scale technical programs - education and integration of interdisciplinary tea
Technology and management of large-scale programs Semiannual progress report
Technology and management of large scale program
\u3cem\u3eRhizobium japonicum\u3c/em\u3e Mutants Defective in Symbiotic Nitrogen Fixation
Rhizobium japonicum strains 3I1b110 and 61A76 were mutagenized to obtain 25 independently derived mutants that produced soybean nodules defective in nitrogen fixation, as assayed by acetylene reduction. The proteins of both the bacterial and the plant portions of the nodules were analyzed by two-dimensional polyacrylamide gel electrophoresis. All of the mutants had lower-than-normal levels of the nitrogenase components, and all but four contained a prominent bacteroid protein not observed in wild-type bacteroids. Experiments with bacteria grown ex planta suggested that this protein was derepressed by the absence of ammonia. Nitrogenase component II of one mutant was altered in isoelectric point. The soluble plant fraction of the nodules of seven mutants had very low levels of heme, yet the nodules of five of these seven mutants contained the polypeptide of leghemoglobin. Thus, the synthesis of the globin may not be coupled to the content of available heme in soybean nodules. The nodules of the other two of these seven mutants lacked not only leghemoglobin but most of the other normal plant and bacteroid proteins. Ultrastructural examination of nodules formed by these two mutants indicated normal ramification of infection threads but suggested a problem in subsequent survival of the bacteria and their release from the infection threads
- …