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The interaction of light with nanometer-sized solids provides the means of focusing optical radiation to sub-wavelength spatial scales with associated electric field enhancements offering new opportunities for multifaceted applications. We utilize collective effects in nanoplasmas with sub-two-cycle light pulses of extreme intensity to extend the waveform-dependent electron acceleration regime into the relativistic realm, by using 106 times higher intensity than previous works to date. Through irradiation of nanometric tungsten needles, we obtain multi-MeV energy electron bunches, whose energy and direction can be steered by the combined effect of the induced near-field and the laser field. We identified a two-step mechanism for the electron acceleration: (i) ejection within a sub-half-optical-cycle into the near-field from the target at >TVm-1 acceleration fields, and (ii) subsequent acceleration in vacuum by the intense laser field. Our observations raise the prospect of isolating and controlling relativistic attosecond electron bunches, and pave the way for next generation electron and photon sources.

The number of stems produced by cool-season forage grasses is a major factor in determining forage production. Knowledge of factors that influence stem numbers will be useful in developing proper management practices. Objectives of this study were to (i) determine total stem numbers and the amount of far-red (FR) and red (R) light at the crown level in canopies of crested wheatgrass (Agropyron desertorum (Fisch. ex Link) Schultes), western wheatgrass (Pascopyrum smithii (Rydb.) Gould), and smooth bromegrass (Bromus inermis Leyss.) that were hayed, grazed, or ungrazed; and (ii) evaluate the relationship between the FR/R ratio at plant crown level and stem numbers. The study was conducted during 1989, 1990, and 1991 at Mandan, ND, USA. Management practices produced differences in both FR/R ratios and stem numbers. Treatment effects on stem numbers were consistent over years for smooth bromegrass whereas treatment X year interactions were significant for crested wheatgrass and western wheatgrass. Generally, stem numbers were greatest for all species that were hayed followed in order by grazed and ungrazed treatments. Grazed and ungrazed plants developed longer leaves and stem internodes than did hayed plants. The relationship between FR/R ratio and stem numbers for all treatments was consistent with previous reports that stem numbers of grasses may be influenced by the FR/R ratio at the crown. The decline in stem numbers of ungrazed stands suggests that to maintain vigorous stands of these species requires an appropriate level of management.

The phenomenon of the privacy paradox states that people are concerned about their data, but do not behave accordingly by avoiding disclosure of personal data, for instance, when using social media. Since findings about the influence of privacy concerns on privacy-related behavior are controversial, the present study investigates whether social norms or individual privacy concerns provide a better explanation of disclosure behavior. Therefore, a social media app dummy was developed and the social norm manipulated by altering the amount and the sensitivity of information provided in a fictitious app user profile. Regarding social norm factors, the results of the online experiment (N = 42) revealed that only the sensitivity of the data in the dummy profile demonstrated a medium effect on the amount of personal data given by the participants. Considering individual factors, the less concerned individuals were about their privacy, the higher were the amount and the degree of sensitivity of the personal information participants disclosed. In addition, participants differentiated between sensitive or non-sensitive information when disclosing their data. They disclosed sensitive information significantly less often, regardless of the dummy profile they saw. Altogether, the study results do not support the privacy paradox and demonstrate implications for media education.