1,720,985 research outputs found
Foetal Radiation Dose During Prophylactic Occlusion Balloon Placement for Morbidly Adherent Placenta
No full textObjective To assess foetal absorbed radiation dose (FAD)
during prophylactic occlusion balloon catheter (POBC) placement
before surgery for morbidly adherent placenta (MAP).
Methods Retrospective cohort study of women with MAP
undergoing POBC before surgery. Women were divided
into two groups. Group 1 treated between 2008 and 2011,
Group 2 between 2012 and 2014 when fluoroscopy pulse
rate reduced from 7.5 to 2 pulses per second. Median and
interquartile range (IQR) of dose area product (DAP) and
FAD were compared using the Mann-U-Whitney test. FAD
was calculated using the PCXMC Monte-Carlo calculation.
All procedures were performed using the same equipment
(Siemens Axiom Artis dTA) by the same experienced interventional
radiology team.
Results Thirty-four women underwent POBC. 16 procedures
were performed in Group 1 and 18 in Group 2. Median
DAP overall was 1025.10 lGym2 (IQR 532.1–1775.3):
Group 1, 1713.25 lGym2 (IQR 1164.5–2274.5) and Group
2, 660.70 lGym2 (IQR 440.9–1020.9) (p= 0.027). Median
FAD overall was 4.65 mGy (IQR 2.7–8.2): Group 1,
6.25 mGy (IQR 4.4–10.6) and Group 2, 3.05 mGy (IQR
2.0–5.4) (p= 0.031).
Conclusions FAD during POBC insertion is low overall.
The only change between the two groups was in pulsed
fluoroscopy rate which resulted in a significant reduction in
FAD. This reinforces the importance of implementation of
dose reduction techniques
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Studying physics during the COVID-19 pandemic: Student assessments of learning achievement, perceived effectiveness of online recitations, and online laboratories
No full textThe COVID-19 pandemic has significantly affected the education system worldwide, which was forced to respond with a sudden shift to distance learning. While successful distance teaching requires careful thinking, planning, and the development of technological and human resources, there was no time for preparation in the current situation. Various physics courses, including lectures, tutorials, and laboratory courses, had to be transferred to online formats, resulting in a variety of simultaneous, asynchronous, and mixed activities. To investigate how physics students perceived the sudden shift to online learning, we developed a questionnaire and gathered data from N=578 physics students from five universities in Germany, Austria, and Croatia. In this article, we report how the problem-solving sessions (recitations) and laboratories were adapted, how students judge the different formats of the courses, and how useful and effective they perceived them. The results are correlated with the students’ self-efficacy ratings and other behavioral measures (such as self-regulated learning skills). This study is descriptive in nature, and a survey study design was implemented to examine the relationships among the variables. We found that good communication abilities (r=0.48, p<0.001) and self-organization skills (r=0.63, p<0.001) are positively correlated with perceived learning achievement. Furthermore, the previous duration of studies had a significant impact on several self-reported achievement measures, resulting in consistently lower scores of students in their first academic year compared with students who were further along academically. We draw conclusions and suggest implications for future online classes on the instructor and faculty level. Suggestions include (i) focusing on first-year courses with on-campus teaching when facing limited lecture hall capacities, (ii) offering special courses for promoting self-regulated learning skills, (iii) emphasizing the positive aspects of distance learning, and (iv) installing networking services for supporting student communication
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Exploring digital signal processing using an interactive Jupyter notebook and smartphone accelerometer data
No full textAbstract Digital signal processing is a valuable practical skill for the contemporary physicist, yet in physics curricula, its central concepts are often introduced either in method courses in a highly abstract and mathematics-oriented manner or in lab work with little explicit attention. In this paper, we present an experimental task in which we focus on a practical implementation of the discrete Fourier transform (DFT) in an everyday context of vibration analysis using data collected by a smartphone accelerometer. Students are accompanied in the experiment by a Jupyter Notebook Companion, which serves as an interactive instruction sheet and a tool for data analysis. The task is suitable for beyond-first-year university physics students with some prior experience in uncertainty analysis, data representation, and data analysis. Based on our observations the experiment is very engaging. Students have consistently reported interest in the experiment and they have found it a good demonstration of the DFT method.Erasmus
Lab courses for prospective physics teachers: what could we learn from the first COVID-19 lockdown?
No full textAbstractAt the universities of Dresden, Vienna, and Zagreb, a laboratory course for prospective physics teachers was transferred to an online environment because of the lockdown in March 2020 due to the COVID-19 pandemic. The aim of this paper is to present and compare students’ and instructors’ considerations about the experiences with this laboratory course at these three universities and to formulate guidelines for organizing lab courses for prospective physics teachers. The research was conducted in three steps: first, interviews were conducted with prospective physics teachers (N = 10); second, an online questionnaire was administered to course participants (N = 99); and third, lab course instructors completed an online questionnaire (N = 8). The results show that an increase in creativity and confidence was expressed when conducting home experiments. Students who received support and guidance benefited more from the online lab course, but some students also experienced a greater time commitment. On a positive note, all participants thought outside-the-box during this lab experience and found solutions that led to new ways of conducting labs. Our study suggests that in future online or regular lab courses, students should have the chance to make decisions about experiments and be creative, with an emphasis on peer discussions and support from instructors
Studying physics during the COVID-19 pandemic: Student perceptions on synchronous and asynchronous course formats and implications for the future
No full textTo investigate how physics students perceived the sudden shift to online learning at the beginning of COVID-19 pandemic, 18 semistructured interviews were conducted with university students in Austria, Croatia, and Germany. Based on the interviews, a questionnaire was developed and data from N=578 physics students from five universities in Germany, Austria, and Croatia were gathered. In this paper, we report how students perceived synchronous and asynchronous physics lessons, how their perception correlates with their self-organization skills, which activities and teaching methods were perceived as helpful, and what are the implications for future physics courses. The most common advantages of synchronous course elements reported by students were the possibility to immediately ask questions, the feeling of community and interaction with other students, and the defined daily structure, whereas the most common advantages of asynchronous course elements reported were flexible time management and the possibility to watch videos at their own pace. The data indicate a correlation between preference for synchronous courses and their general self-organization, so instructors should be aware of this connection when planning future courses. Face-to-face lectures at university were perceived as the most helpful course element, followed by the recorded lectures from the instructor and the group work on the assignments, projects, and problems with other students. Furthermore, our results suggest that most students would in the future like to preserve the upload of learning materials and recorded video of the lectures in addition to classroom lectures. Overall, the results of this study suggest that both synchronous and asynchronous course elements should be combined in future online and in-person physics courses
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