1,991 research outputs found
Different Behavior of Magnetic Impurities in Crystalline and Ammorphous States of Superconductors
It has been observed that the effect of magnetic impurities in a
superconductor is drastically different depending on whether the host
superconductor is in a crystalline or an amorphous state. Based on the recent
theory of Kim and Overhauser (KO), it is shown that as the system is getting
disordered, the initial slope of the depression is decreasing by a
factor , when the mean free path becomes smaller
than the BCS coherence length , which is in agreement with
experimental findings. In addition, for a superconductor in a crystalline state
in the presence of magnetic impurities the superconducting transition
temperature drops sharply from about 50% of (for a pure
system) to zero near the critical impurity concentration. This {\sl pure limit
behavior} was indeed found by Roden and Zimmermeyer in crystalline Cd.
Recently, Porto and Parpia have also found the same {\sl pure limit behavior}
in superfluid He-3 in aerogel, which may be understood within the framework of
the KO theory.Comment: 7 figures, 20 pages, latex, to appear in Superconductor Science and
Technolog
Impurity scattering in a d-wave superconductor
The influence of (non-magnetic and magnetic) impurities on the transition
temperature of a d-wave superconductor is studied anew within the framework of
BCS theory. Pairing interaction decreases linearly with the impurity
concentration. Accordingly suppression is proportional to the
(potential or exchange) scattering rate, , due to impurities. The
initial slope versus is found to depend on the superconductor contrary
to Abrikosov-Gor'kov type theory. Near the critical impurity concentration
drops abruptly to zero. Because the potential scattering rate is
generally much larger than the exchange scattering rate, magnetic impurities
will also act as non-magnetic impurities as far as the decrease is
concerned. The implication for the impurity doping effect in high
superconductors is also discussed.Comment: 12 pages and 1 figure, PlainTex, submitted to Mod. Phys. Lett. B, For
more information, please see "http://taesan.kaist.ac.kr/~yjkim
Psychophysiological and Psychological Responses of Teenage Students Conducting Computer Programming Activities Combined with Horticultural Activities
This study investigated whether coding (computer programming) and horticultural activities alone and combined have psychophysiological and psychological effects. Compulsory computer programming has been required in elementary schools in South Korea since 2018. A total of 34 participants, who were students between the ages of 11 and 16 years were involved in the study. Participants undertook the following activities in random order: connecting components, coding, horticultural activities, and combining coding and horticultural activities (run program, horticultural activities, and coding modifications). Brain waves were measured during the activity, and a subjective self-report evaluation was conducted at the end of each activity. In a spectral edge frequency of 50% of the alpha spectrum band, which indicates a comfortable, stable, and relaxed state, there was a significant difference in the left prefrontal pole when participants performed a combination of coding and horticultural activities (P < 0.001). In addition, there were significant differences in the coding activities based on horticultural activities (P < 0.05, P < 0.001), with a relatively low beta, indicating attention and alertness; relative mid beta, indicating active awareness; ratio of SMR to theta, indicating focused attention; and the ratio of mid beta to theta, indicating concentrated focus. It is judged that activities involving plant engagement can contribute to comfort, stability, focused attention, and positive effects in response to active stimuli. As a result of a subjective evaluation, it was found that horticultural activities had a positive effect on participants’ emotions (P < 0.01). This study demonstrates that horticulture-based coding activities have a positive impact on physiological relaxation and cognitive enhancement, and are also associated with subjectively reported positive emotions
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Detection of Murine Post-Pneumonectomy Lung Regeneration by 18FDG PET Imaging
Background: An intriguing biologic process in most adult mammals is post-pneumonectomy lung regeneration, that is, the removal of one lung (pneumonectomy) results in the rapid compensatory growth of the remaining lung. The spatial dependence and metabolic activity of the rodent lung during compensatory lung regeneration is largely unknown. Methods: To determine if murine lung regeneration could be detected in vivo, we studied inbred mice 3, 7, 14, and 21 days after left pneumonectomy. The remaining lung was imaged using microCT as well as the glucose tracer 2-deoxy-2-[18 F]fluoro-d-glucose (18FDG) and positron-emission tomography (PET). Because of the compliance of the murine chest wall, reproducible imaging required orotracheal intubation and pressure-controlled ventilation during scanning. Results: After left pneumonectomy, the right lung progressively enlarged over the first 3 weeks. The cardiac lobe demonstrated the greatest percentage increase in size. Dry weights of the individual lobes largely mirrored the increase in lung volume. PET/CT imaging was used to identify enhanced metabolic activity within the individual lobes. In the cardiac lobe, 18FDG uptake was significantly increased in the day 14 cardiac lobe relative to preoperative values (p < .05). In contrast, the 18FDG uptake in the other three lobes was not statistically significant at any time point. Conclusions: We conclude that the cardiac lobe is the dominant contributor to compensatory growth after murine pneumonectomy. Further, PET/CT scanning can detect both the volumetric increase and the metabolic changes associated with the regenerative growth in the murine cardiac lobe
Culture supernatant of adipose stem cells can ameliorate allergic airway inflammation via recruitment of CD4+CD25+Foxp3 T cells
SDS-PAGE of supernatant after ASC cultivation. Comparison of protein composition of con sup (concentrated medium for ASCs cultivation) and ASC sup (concentrated culture supernatant after ASC cultivation for 3 days) using SDS-PAGE. Thirty micrograms of each sample was loaded into an SDS-PAGE gel. After electrophoresis, the gel was stained by Coomassie Blue (M molecular marker, arrow indicated extra proteins compared to control). (PPT 370 kb
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