Interaction-time effects of quasifree processes

Author(s):  
J. M. Lambert ◽  
P. A. reado ◽  
R. A. Moyle ◽  
L. T. Myers ◽  
Ivo Slaus
Author(s):  
Kira Bailey ◽  
Bruce D. Bartholow ◽  
J. Scott Saults ◽  
Sarah A. Lust

1986 ◽  
Vol 47 (12) ◽  
pp. 2025-2039 ◽  
Author(s):  
A. Titov ◽  
Yu. Malyshev ◽  
Yu. Rastorguev

2003 ◽  
Vol 762 ◽  
Author(s):  
C. Smit ◽  
D.L. Williamson ◽  
M.C.M. van de Sanden ◽  
R.A.C.M.M. van Swaaij

AbstractExpanding thermal plasma CVD (ETP CVD) has been used to deposit thin microcrystalline silicon films. In this study we varied the position at which the silane is injected in the expanding hydrogen plasma: relatively far from the substrate and close to the plasma source, giving a long interaction time of the plasma with the silane, and close to the substrate, resulting in a short interaction time. The material structure is studied extensively. The crystalline fractions as obtained from Raman spectroscopy as well as from X-ray diffraction (XRD) vary from 0 to 67%. The average particle sizes vary from 6 to 17 nm as estimated from the (111) XRD peak using the Scherrer formula. Small angle X-ray scattering (SAXS) and flotation density measurements indicate void volume fractions of about 4 to 6%. When the samples are tilted the SAXS signal is lower than for the untilted case, indicating elongated objects parallel to the growth direction in the films. We show that the material properties are influenced by the position of silane injection in the reactor, indicating a change in the plasma chemistry.


2013 ◽  
Vol 1 (2) ◽  
pp. 209-234 ◽  
Author(s):  
Pengyuan Wang ◽  
Mikhail Traskin ◽  
Dylan S. Small

AbstractThe before-and-after study with multiple unaffected control groups is widely applied to study treatment effects. The current methods usually assume that the control groups’ differences between the before and after periods, i.e. the group time effects, follow a normal distribution. However, there is usually no strong a priori evidence for the normality assumption, and there are not enough control groups to check the assumption. We propose to use a flexible skew-t distribution family to model group time effects, and consider a range of plausible skew-t distributions. Based on the skew-t distribution assumption, we propose a robust-t method to guarantee nominal significance level under a wide range of skew-t distributions, and hence make the inference robust to misspecification of the distribution of group time effects. We also propose a two-stage approach, which has lower power compared to the robust-t method, but provides an opportunity to conduct sensitivity analysis. Hence, the overall method of analysis is to use the robust-t method to test for the overall hypothesized range of shapes of group variation; if the test fails to reject, use the two-stage method to conduct a sensitivity analysis to see if there is a subset of group variation parameters for which we can be confident that there is a treatment effect. We apply the proposed methods to two datasets. One dataset is from the Current Population Survey (CPS) to study the impact of the Mariel Boatlift on Miami unemployment rates between 1979 and 1982.The other dataset contains the student enrollment and grade repeating data in West Germany in the 1960s with which we study the impact of the short school year in 1966–1967 on grade repeating rates.


2021 ◽  
Author(s):  
Tibor Guzsvinecz ◽  
Éva Orbán-Mihálykó ◽  
Cecília Sik-Lányi ◽  
Erika Perge

AbstractThe interaction time of students who did spatial ability tests in a virtual reality environment is analyzed. The spatial ability test completion times of 240 and 61 students were measured. A desktop display as well as the Gear VR were used by the former group and by the latter one, respectively. Logistic regression analysis was used to investigate the relationship between the probability of correct answers and completion times, while linear regression was used to evaluate effects and interactions of following factors on test completion times: the users’ gender and primary hand, test type and device used. The findings were that while the completion times are not significantly affected by the users’ primary hand, other factors have significant effects on them: they are decreased by the male gender in itself, while they are increased by solving Mental Rotation Tests or by using the Gear VR. The largest significant increment in interaction time in virtual reality during spatial ability tests is when Mental Rotation Tests are accomplished by males with the Gear VR, while the largest significant decrease in interaction time is when Mental Cutting Tests are completed with a desktop display.


2018 ◽  
Vol 108 ◽  
pp. 74-89 ◽  
Author(s):  
Karen R. Lindsay ◽  
Michael P. Popp ◽  
Charles P. West ◽  
Amanda J. Ashworth ◽  
Alexandre Caldeira Rocateli ◽  
...  

2021 ◽  
Vol 11 (5) ◽  
pp. 244
Author(s):  
Maria Kramer ◽  
Christian Förtsch ◽  
Birgit J. Neuhaus

In a diagnostic context of reasoning about instructional quality, scientific reasoning skills can be described as diagnostic activities, which require professional knowledge. Different approaches to enhance pre-service teachers’ professional knowledge (PCK, CK, PK), as well as diagnostic activities exist. However, results about their effectiveness are still inconsistent. We systematically investigated the effectiveness of self-directed knowledge acquisition via texts on PCK, CK, PK, and diagnostic activities of 81 pre-service biology teachers following an experimental design. Paper-pencil tests, measuring PCK, CK, and PK, and the video-based assessment tool DiKoBi Assess, measuring diagnostic activities in the context of diagnosing instructional quality, were used pre and post an intervention. Intervention included four treatments on self-directed knowledge acquisition via texts on (1) PCK, (2) CK, (3) PK, (4) combination PCK/CK/PK. Treatment (5) served as control. Mixed ANOVAs showed large time effects for PCK and CK, but no interaction effect concerning knowledge facets between time and treatment for any of the treatments. Time effects might be due to pre-service teachers’ scientific reasoning on biology instruction that activated knowledge. An ANCOVA showed no significant effect of treatment on diagnostic activities either. We conclude that scientific reasoning about instructional quality is more effective for knowledge acquisition than text-work.


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