Aspherical mirror online testing using phase retrieval with stitching

Optik ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 3549-3553
Author(s):  
Chao Xie ◽  
Junfeng Cui ◽  
Yanming Liang
Author(s):  
W. Coene ◽  
A. Thust ◽  
M. Op de Beeck ◽  
D. Van Dyck

Compared to conventional electron sources, the use of a highly coherent field-emission gun (FEG) in TEM improves the information resolution considerably. A direct interpretation of this extra information, however, is hampered since amplitude and phase of the electron wave are scrambled in a complicated way upon transfer from the specimen exit plane through the objective lens towards the image plane. In order to make the additional high-resolution information interpretable, a phase retrieval procedure is applied, which yields the aberration-corrected electron wave from a focal series of HRTEM images (Coene et al, 1992).Kirkland (1984) tackled non-linear image reconstruction using a recursive least-squares formalism in which the electron wave is modified stepwise towards the solution which optimally matches the contrast features in the experimental through-focus series. The original algorithm suffers from two major drawbacks : first, the result depends strongly on the quality of the initial guess of the first step, second, the processing time is impractically high.


Author(s):  
Peter P. J. L. Verkoeijen ◽  
Remy M. J. P. Rikers ◽  
Henk G. Schmidt

Abstract. The spacing effect refers to the finding that memory for repeated items improves when the interrepetition interval increases. To explain the spacing effect in free-recall tasks, a two-factor model has been put forward that combines mechanisms of contextual variability and study-phase retrieval (e.g., Raaijmakers, 2003 ; Verkoeijen, Rikers, & Schmidt, 2004 ). An important, yet untested, implication of this model is that free recall of repetitions should follow an inverted u-shaped relationship with interrepetition spacing. To demonstrate the suggested relationship an experiment was conducted. Participants studied a word list, consisting of items repeated at different interrepetition intervals, either under incidental or under intentional learning instructions. Subsequently, participants received a free-recall test. The results revealed an inverted u-shaped relationship between free recall and interrepetition spacing in both the incidental-learning condition and the intentional-learning condition. Moreover, for intentionally learned repetitions, the maximum free-recall performance was located at a longer interrepetition interval than for incidentally learned repetitions. These findings are interpreted in terms of the two-factor model of spacing effects in free-recall tasks.


2007 ◽  
Author(s):  
Peter M. Wessels ◽  
Jonathan Schnader ◽  
Allison Smith ◽  
Christopher Thomas ◽  
Haley Titus

2003 ◽  
Vol 104 ◽  
pp. 557-561 ◽  
Author(s):  
M. R. Howells ◽  
H. Chapman ◽  
S. Hau-Riege ◽  
H. He ◽  
S. Marchesini ◽  
...  

2020 ◽  
Author(s):  
Stella F. Lourenco ◽  
Arber Tasimi

Cognitive scientists have ramped up online testing in response to the coronavirus pandemic. Although research conducted online solves the problem of data collection, a lack of internet access among low-income and minority communities may reduce the diversity of study samples and, thus, impact the generalizability of scientific findings.


2018 ◽  
Vol 22 (2) ◽  
pp. 353-356
Author(s):  
V.P. Kovalchuk ◽  
I.M. Kovalenko ◽  
S.V. Kovalenko ◽  
V.M. Burkot ◽  
V.O. Kovalenko

Innovations change the world in all spheres of life, and education is not an exception. Modern requirements of time put us new challenges that require the use of new information technologies at all stages of the educational process in higher education institutions, in particular the use of the Internet. In addition, it has been noted that Internet resources increase motivation and contribute to the formation of a fully developed personality. Testing and evaluating students' knowledge and abilities is an integral part of the credit-module system. One of the forms of evaluation of the initial level of knowledge, consolidation and improvement of assimilation of information is testing. It should be noted that in a number of countries, testing has shifted traditional forms of control — oral and written exams and interviews. However, in Ukraine, educators remain adherents of a combination of testing and classical analysis of material. It allows the most efficient distribution of the training time of a practical class, 100% control of the knowledge and the effectiveness of mastering the material of all the students of the academic group. Technical progress stimulates the search for new variants and possibilities of testing, its various variations. One of the options that can help solve this problem was a smartphone. In order to facilitate the work of the teacher at the Department of Microbiology, an online testing system with the use of smartphones was introduced. Online testing is conducted among students with Ukrainian and English language training. With the Google Forms platform, the teacher creates a form which contains the student's records and tests. Students directly from the teacher get a link to fill out an online form directly at the lesson. For testing, a database containing standard KROK-1 licensed test tasks is used. The form can contain any number of test tasks that are in arbitrary order, as well as a changed order of distractors, which makes it impossible to write off. At the same time, all students are in the same conditions: all write one option. After submitting the form, the student receives a notification that his response is recorded. Re-linking is not possible. In turn, the teacher receives a message on the result of the test in the table — the ratio of correct answers to the total number of questions, as well as options for their answers. First and foremost, questions are displayed on which students gave the largest number of incorrect answers. This allows the topic to be considered in the process of discussion of the most difficult tasks from the students perspective, and in the future it will allow more efficiently to create forms for on-line tests and to focus on these issues.


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