3,957 research outputs found
Apparent suppression of turbulent magnetic dynamo action by a dc magnetic field
Numerical studies of the effect of a dc magnetic field on dynamo action
(development of magnetic fields with large spatial scales), due to
helically-driven magnetohydrodynamic turbulence, are reported. The apparent
effect of the dc magnetic field is to suppress the dynamo action, above a
relatively low threshold. However, the possibility that the suppression results
from an improper combination of rectangular triply spatially-periodic boundary
conditions and a uniform dc magnetic field is addressed: heretofore a common
and convenient computational convention in turbulence investigations. Physical
reasons for the observed suppression are suggested. Other geometries and
boundary conditions are offered for which the dynamo action is expected not to
be suppressed by the presence of a dc magnetic field component.Comment: To appear in Physics of Plasma
A reduced magnetohydrodynamic model of coronal heating in open magnetic regions driven by reflected low-frequency waves
A reduced magnetohydrodynamic (RMHD) description is employed to examine a suggestion made by W. H. Matthaeus and colleagues in 1999 that coronal heating might be sustained by a cascade of low-frequency MHD turbulence. Here RMHD simulations show that the low-frequency cascade to high transverse wavenumbers can be driven by an externally maintained flux of low-frequency propagating Alfvén waves, in combination with reflection caused by an inhomogeneous background medium. The simulations show that the suggestions made previously on the basis of a phenomenology are indeed realizable. In addition, the effect is seen to sensitively depend on the presence of reflection, as the background turbulence level needed to maintain the cascade can be sustained only when reflection is imposed. The steady level of turbulence is insensitive to the initial seed turbulence level (provided it is nonzero). Consequences of this model for realistic models of coronal heating in open field-line regions are discussed
Exploiting the photoactivity of bacterial reaction center to investigate liposome dynamics
Charge recombination kinetics of bacterial photosynthetic protein Reaction Center displays an exquisite sensitivity to the actual occupancy of ubiquinone-10 in its QB-binding site. Here, we have exploited such phenomenon for assessing the growth and the aggregation/fusion of phosphocholine vesicles embedding RC in their membrane, when treated with sodium oleate
Social media engagement and organic post effectiveness: A roadmap for increasing the effectiveness of social media use in hospitality industry
The present study assessed the social media use behavior of luxury hospitality facilities and offers suggestions to improve organic post effectiveness. All five-star tourism facilities operating in Turkey were incorporated into the study and publicly available post data on Facebook accounts of 441 facilities (out of a total of 612) were examined in the high tourist season (August) for one month. Data on 2,012 Facebook posts were obtained manually and filtered down to 1,847. The collected post data were subsequently coded using a content analysis form and analyzed via ordinal regression. The results highlighted the positive effects of interactive content and vivid content as well as the significance of the content type in achieving higher interaction among followers. The facility location and category (hotel, holiday village, thermal hotel) also emerged as significant factors affecting follower interactions
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