63 research outputs found
Nonequilibrium Magnetization Dynamics of Nickel
Ultrafast magnetization dynamics of nickel has been studied for different
degrees of electronic excitation, using pump-probe second-harmonic generation
with 150 fs/800 nm laser pulses of various fluences. Information about the
electronic and magnetic response to laser irradiation is obtained from sums and
differences of the SHG intensity for opposite magnetization directions. The
classical M(T)-curve can be reproduced for delay times larger than the electron
thermalization time of about 280 fs, even when electrons and lattice have not
reached thermal equilibrium. Further we show that the transient magnetization
reaches its minimum approx. 50 fs before electron thermalization is completed.Comment: 8 pages, 5 figures, revte
Perceived Differences in Knowledge About Interactive Technology Between Young Adults and Their Parents
This study was designed to investigate generational differences in knowledge about interactive technology (i.e., cell phones, social networking, email, video chat) between parents and their young adult children. Parents (n = 555) and young adults (n = 604) residing in the United States provided information about their knowledge in the use of interactive technology. Young adult children also reported their perceptions of their parents’ technological knowledge for the various technologies. Comparisons of young adult self-reported technological knowledge and their parents’ own reports of technological knowledge revealed that young adults were perceived to be much more knowledgeable than their parents (by both the young adults and their parents) regardless of the technology medium. The largest differences between parents and their young adult children were associated with newer interactive technologies, with the largest gap between parent and young adult knowledge in the area of social networking. Perceived differences between parents and their young adult children were smaller among the technologies that have been in use longer (such as such as e-mail), and larger among the newer modes of interactive technology (e.g., video chat)
Ultrafast spin dynamics and critical behavior in half-metallic ferromagnet : Sr_2FeMoO_6
Ultrafast spin dynamics in ferromagnetic half-metallic compound Sr_2FeMoO_6
is investigated by pump-probe measurements of magneto-optical Kerr effect.
Half-metallic nature of this material gives rise to anomalous thermal
insulation between spins and electrons, and allows us to pursue the spin
dynamics from a few to several hundred picoseconds after the optical
excitation. The optically detected magnetization dynamics clearly shows the
crossover from microscopic photoinduced demagnetization to macroscopic critical
behavior with universal power law divergence of relaxation time for wide
dynamical critical region.Comment: 14 pages, 4 figures. Abstract and Figures 1 & 3 are correcte
Ultrafast Spin Dynamics in Nickel
The spin dynamics in Ni is studied by an exact diagonalization method on the
ultrafast time scale. It is shown that the femtosecond relaxation of the
magneto-optical response results from exchange interaction and spin-orbit
coupling. Each of the two mechanisms affects the relaxation process
differently. We find that the intrinsic spin dynamics occurs during about 10 fs
while extrinsic effects such as laser-pulse duration and spectral width can
slow down the observed dynamics considerably. Thus, our theory indicates that
there is still room to accelerate the spin dynamics in experiments.Comment: 4 pages, Latex, 4 postscript figure
Using a Temporal-Causal Network Model for Computational Analysis of the Effect of Social Media Influencers on the Worldwide Interest in Veganism
Nonlinear Magneto-Optical Response of - and -Wave Superconductors
The nonlinear magneto-optical response of - and -wave superconductors
is discussed. We carry out the symmetry analysis of the nonlinear
magneto-optical susceptibility in the superconducting state. Due to the surface
sensitivity of the nonlinear optical response for systems with bulk inversion
symmetry, we perform a group theoretical classification of the superconducting
order parameter close to a surface. For the first time, the mixing of singlet
and triplet pairing states induced by spin-orbit coupling is systematically
taken into account. We show that the interference of singlet and triplet
pairing states leads to an observable contribution of the nonlinear
magneto-optical Kerr effect. This effect is not only sensitive to the
anisotropy of the gap function but also to the symmetry itself. In view of the
current discussion of the order parameter symmetry of High-T
superconductors, results for a tetragonal system with bulk singlet pairing for
various pairing symmetries are discussed.Comment: 21 pages (REVTeX) with 8 figures (Postscript
Social media for health promotion and weight management: A critical debate
© 2018 The Author(s). Background: In 2016 an estimated 1.9 billion adults world-wide were either overweight or obese. The health consequences of obesity are responsible for 2.8 million preventable deaths per year. The WHO now considers obesity as a global epidemic and recommends population-wide health promotion strategies to address this issue. Weight gain is caused by increased energy intake and physical inactivity, so treatment should focus on changes to behaviour regarding diet and physical activity. Discussion: The WHO has also recognised the importance of social resources as a valuable agent for behaviour change in health promotion. Social resources are translated at the community level as support provided by significant others such as family, partners and peers, in the form of information, material aid and encouragement. Social support has been shown to improve health and well-being, whereas social isolation has been shown to have a negative impact on health outcomes. Social support provided by peers has been shown to be a useful strategy to employ in weight management programmes. The documented increased use of ICT and social media has presented health promoters with a potentially useful medium to increase social support for weight management. Conclusion: While the use of social media for health promotion is an emerging field of investigation, preliminary research suggests that it increases participant engagement, and may provide a cost-effective tool to provide social support for individuals participating in weight management programmes. With stringent privacy protocols in place, social media may be a useful, cost-effective accompaniment to multifactorial weight management programmes. However more research is needed to identify how to make the best use of social media as health promotion tool
Adsorbate and thermally induced spin reorientation transition in low-temperature-grown Fe/Cu(001)
Differences in growth rates and pre-hibernation body mass gain between early and late-born juvenile garden dormice
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