In a non-selected population comprising 15,241 women, an evaluation was performed of the ultrasonic measurement of the biparietal diameter compared with a reliable last menstrual period as the basis for estimation of the day of delivery. In women with a reliable menstrual history and spontaneous onset of labor, the ultrasound estimate was the significantly better predictor of the day of delivery in 52% of cases, and the last menstrual period estimate was the better predictor in 46% of cases. The percentages of women who delivered within 7 days of the predicted day were 61 and 56% for the ultrasound and the last menstrual period estimations, respectively. There was a significantly narrower distribution of births according to the ultrasound estimate (p < 0.001). The proportion of estimated postterm births was 4% using the ultrasound method and 10% using the last menstrual period method (p < 0.001). Even when the difference between the methods in predicting the day of delivery was less than 7 days, the ultrasound method was better than the last menstrual period method. It is concluded that ultrasonic measurement of the biparietal diameter between 15 and 22 weeks of pregnancy is the best method for the estimation of the day of delivery and should be used as a routine procedure.

No abstract

No abstract

Objectives

Objective To compare gestational age (GA)

Kelson and Distlehorst (2000) state the PBL outcomes should be discussed on a broad basis including a useable knowledge base, skills in problem solving, self-directed learning and collaboration. The present research compares students in a PBL programme and in a traditional program on learning strategies, mental models and outcomes. Learning strategies and metal models of learning were measured for two student groups in 2001 using an adaptation of Vermunt's (1994) "Inventory of learning styles". Learning outcomes were measured for the same groups in 2002 using a test of medical knowledge. PBL-students showed significantly more self-regulated learning and more constructive conceptions of learning. No significant differences in learning outcomes were found between the two groups. Students in the PBL-programme perceived students as more active contributors to group learning process and made use of a broader range of resources than students in the traditional programme. The findings confirm effects of educational programmes on student learning strategies (Vermetten 1999) and also confirm lack of significant differences in medical knowledge (Albanese 2000, Colliver 2000, Norman & Schmidt 2000, Wiers-Jensen & Aasland 2004). The curricular influence on students' learning strategies challenges educators to design approaches that promote lifelong learning skills as well as disciplinary knowledge.

Trigger Ca(2+) is considered to be the Ca(2+) current through the L-type Ca(2+) channel (LTCC) that causes release of Ca(2+) from the sarcoplasmic reticulum. However, cell contraction also occurs in the absence of the LTCC current (I(Ca)). In this article, we investigate the contribution of the Na(+)/Ca(2+) exchanger (NCX) to the trigger Ca(2+). Experimental data from rat cardiomyocytes using confocal microscopy indicating that inhibition of reverse mode Na(+)/Ca(2+) exchange delays the Ca(2+) transient by 3-4 ms served as a basis for the mathematical model. A detailed computational model of the dyadic cleft (fuzzy space) is presented where the diffusion of both Na(+) and Ca(2+) is taken into account. Ionic channels are included at discrete locations, making it possible to study the effect of channel position and colocalization. The simulations indicate that if a Na(+) channel is present in the fuzzy space, the NCX is able to bring enough Ca(2+) into the cell to affect the timing of release. However, this critically depends on channel placement and local diffusion properties. With fuzzy space diffusion in the order of four orders of magnitude lower than in water, triggering through LTCC alone was up to 5 ms slower than with the presence of a Na(+) channel and NCX.

Students' general approaches to learning were not affected by the introduction of DPBL. However, there was a decrease in students' expectations concerning activity in the group and the importance of the tutor. These changes were related to students' familiarity with the use of computers. Web-based resources and experts became more important resources to the students during the DPBL period.