Measuring the P-odd Pion-Nucleon Coupling h_{\pi NN}^{(1)} in \pi^+ Photoproton Production Near the Threshold

We show that polarized gamma p -> \pi^+ n in the threshold region is an excellent candidate for measuring the leading parity-violating pion-nucleon coupling h_{\pi NN}^{(1)} to an uncertainty of 20% if it has a natural size from dimensional analysis. The conclusion is based on a large unpolarized cross section, a new low-energy theorem for the photon polarization asymmetry at the threshold A_\gamma|_{th} = \sqrt{2} f_\pi (\mu_p-\mu_n) h_{\pi NN}^{(1)}/g_A m_N \sim h_{\pi NN}^{(1)}/2, and its strong dominance at forward and backward angles in the threshold region.Comment: 4 pages, 3 figures. More data points in fig. 1 and note added in proof adde

Superiority of collaborative learning with complex tasks: A research note on an alternative affective explanation

Kirschner, F., Paas, F., & Kirschner, P. A. (2011). Superiority of collaborative learning with complex tasks: A research note on an alternative affective explanation. Computers in Human Behavior, 27(1), 53-57. doi:10.1016/j.chb.2010.05.012Kirschner, Paas, and Kirschner (2009c) used the theoretical framework of cognitive load to explain why the learning of a group of collaborating individuals was more efficient than that of individuals learning alone with high-complexity tasks but not with low-complexity tasks. The authors argued that collaboration circumvented the limitations of an individual’s working memory by creating an expanded cognitive capacity and by allowing for the distribution of cognitive load among group members. Inspired by research on efficacy, this study explored an alternative affective explanation of the results. By measuring the amount of mental effort learners expected to invest in working on a learning task before actually carrying out the task, this study showed that learners who had to collaboratively solve a high-complexity problem expected to invest less mental effort than learners who had to solve the problem alone. When confronted with low-complexity tasks, the expected amount of mental effort did not differ

Time-Clamped, RPE-Matched Treadmill Activity and Interactive Video Game Dancing Differ in Step Count But Not Heart Rate Response

Background: Participation in regular moderate or vigorous physical activity (MVPA) results in numerous health benefits. Task enjoyment is a known antecedent and promoter of regular activity engagement. Participation in interactive video gaming has increased in recent years. Purpose: The aims of the present investigation were to: 1) determine heart rate (HR) and step count outcomes of time-clamped and RPE-matched interactive video game dancing (VGD) and treadmill activity; 2) characterize the suitability of VGD to achieve MVPA designation; and, 3) investigate step count outcomes recorded by pedometry and accelerometry. Methods: Subjects underwent three testing sessions with the latter two randomized. During the familiarization visit, the perceived exertion (Borg RPE) of an interactive VGD activity was determined and a treadmill speed that resulted in an RPE-matched exertion level was identified through incremental increases in treadmill speed. On subsequent visits, subjects completed 15 minutes of VGD or RPE-matched treadmill activity. HR and step count were measured during both sessions. Results: Nine participants (Age 19.8 ± 1.6; 5 males; 4 females) volunteered. With time-clamped and RPE-matched, the average HR for dancing 154.7 (± 21.8) and treadmill activity 157.8 (± 25.1) were not different (p = 0.698). The selected dances for the VGD activity resulted in 8/9 subjects exercising at MVPA intensity according to percent of predicted maximal HR (threshold of 64% maximal HR; equation: 207 – 0.7*Age). Steps completed during dancing and treadmill activity according to pedometry were 1510 (± 488) and 2066 (± 247), respectively, with the difference being significant (p = 0.001). Steps completed during dancing and the treadmill activity according to accelerometry were 988 (± 256) and 1938 (± 119), respectively, with the difference again significant (p \u3c 0.001). The within-mode, between-device step count (pedometer vs. accelerometer, respectively) were also of interest. For dancing, a significant difference (p \u3c 0.001) was noted as 1510 (± 488) vs. 988 (± 256) steps. For treadmill activity, the disparity between 2066 (± 247) vs. 1938 (± 119) was also different (p = 0.042). Discussion: The HR response of a VGD activity was not different than a time-clamped, RPE-matched treadmill activity. Furthermore, VGD achieved designation as MVPA intensity in 8/9 subjects with the lone subject failing to achieve moderate designation by a single beat. Of note, objectively determined step count varied by mode and measuring device illustrating the need to employee prudency when selecting measuring technique for step count during rhythmic vs. non-rhythmic PA

Polarization transfer in e⃗+p→e+p⃗\vec{e}^+p \rightarrow e^+ \vec{p} scattering using the Super BigBite Spectrometer

The effects of multi-photon-exchange and other higher-order QED corrections on elastic electron-proton scattering have been a subject of high experimental and theoretical interest since the polarization transfer measurements of the proton electromagnetic form factor ratio $G_E^p/G_M^p$ at large momentum transfer $Q^2$ conclusively established the strong decrease of this ratio with $Q^2$ for $Q^2 \gtrsim 1$ GeV$^2$. This result is incompatible with previous extractions of this quantity from cross section measurements using the Rosenbluth Separation technique. Much experimental attention has been focused on extracting the two-photon exchange (TPE) effect through the unpolarized $e^+p/e^-p$ cross section ratio, but polarization transfer in polarized elastic scattering can also reveal evidence of hard two-photon exchange. Furthermore, it has a different sensitivity to the generalized TPE form factors, meaning that measurements provide new information that cannot be gleaned from unpolarized scattering alone. Both $\epsilon$-dependence of polarization transfer at fixed $Q^2$, and deviations between electron-proton and positron-proton scattering are key signatures of hard TPE. A polarized positron beam at Jefferson Lab would present a unique opportunity to make the first measurement of positron polarization transfer, and comparison with electron-scattering data would place valuable constraints on hard TPE. Here, we propose a measurement program in Hall A that combines the Super BigBite Spectrometer for measuring recoil proton polarization, with a non-magnetic calorimetric detector for triggering on elastically scattered positrons. Though the reduced beam current of the positron beam will restrict the kinematic reach, this measurement will have very small systematic uncertainties, making it a clean probe of TPE.Comment: 6 pages, 3 figures. Contribution to the EPJA topical issue, "An Experimental Program with Positron Beams at Jefferson Lab." arXiv admin note: substantial text overlap with arXiv:2007.15081, arXiv:1906.0941

Replication Study: Undergraduate Students Balancing Paid Semester Work and Study

The current study of student semester­time paid work uses the questionnaire from the earlier by Manthei & Gilmore. They gathered data from an Education Faculty, 83 undergraduates using a questionnaire asking about degree study and part­time paid work while studying. They note in their article that there is no similar data in New Zealand (2005, p. 202). While a number of Australian studies can be found in the literature, the aim of the present study is in replicating Manthei and Gilmore’s work to provide additional New Zealand data and also to see whether findings are consistent with the polytechnic sector. Further, two developments, first, the move to cap university places, and second, tighten quality assurance focus on student achievement and retention, will have consequences for all institutions in the tertiary system. Measuring students’ part­time paid work is an important aspect in assessing consequences for students’ academic work, and policy settings that might follow. Whether the results differ or are similar, this research process widens out the evidential base of the earlier study. Manthei & Gilmore were at pains in the conclusion of their article to caution about over­generalisation from their one study