Time-domain control of ultrahigh-frequency nanomechanical systems

Nanoelectromechanical systems could have applications in fields as diverse as ultrasensitive mass detection and mechanical computation, and can also be used to explore fundamental phenomena such as quantized heat conductance and quantum-limited displacement. Most nanomechanical studies to date have been performed in the frequency domain. However, applications in computation and information storage will require transient excitation and high-speed time-domain operation of nanomechanical systems. Here we show a time-resolved optical approach to the transduction of ultrahigh-frequency nanoelectromechanical systems, and demonstrate that coherent control of nanomechanical oscillation is possible through appropriate pulse programming. A series of cantilevers with resonant frequencies ranging from less than 10 MHz to over 1 GHz are characterized using the same pulse parameters.

Spin-orbit hybridization points in the face-centered-cubic cobalt band structure

Linear magnetic dichroism is observed in spin-, time-, and energy-resolved two-photon photoemission from valence bands of epitaxial fcc cobalt on Cu(001). With image-potential states as spectator states we identify initial bulk and surface states with minority spin character as the source for dichroic intensities and apparent dichroic lifetimes. Excellent agreement with ab initio fully relativistic calculations of the cobalt fcc band structure allows us to precisely determine spin-orbit hybridization points close to the Fermi level. These spin hot spots enhance spin-flip scattering by several orders of magnitude and are therefore assumed to be crucial in ultrafast demagnetization.

[The implementation of Individual Placement and Support in the Netherlands]

BACKGROUND

Individual Placement and Support is a vocational rehabilitation programme for people with severe mental illness, which was implemented during the period 2003-2005 at four locations in the Netherlands.

AIM

To investigate the degree of compliance with the Individual Placement and Support programme, the factors that hindered or facilitated its implementation, and the results.

METHOD

The degree of compliance was assessed using the Individual Placement and Support fidelity scale. Data regarding the factors that hindered or facilitated the implementation were collected via interviews and monitoring. In addition, data were collected on patient characteristics, the support provided and the jobs found.

RESULTS

None of the locations achieved the highest level of compliance, although two locations came close. Eighteen per cent of the 316 patients were helped to find a regular job. The most important obstacles to implementation were loss of vocational team members, project leaders' lack of time, lack of finance, and insufficient cooperation between the organisations involved. The most important facilitating factors were the skills and commitment of the vocational team member(s) and the integration of the vocational teammember(s) and the mental health team.

CONCLUSION

It is not easy to implement Individual Placement and Support. However, if more attention is given to good project management, Individual Placement and Support can succeed in the Netherlands.

Spin-wave interference in microscopic rings

We have studied the spin excitations of ferromagnetic rings and observed a distinct series of quantized modes in the vortex state. We attribute them to spin waves that circulate around the ring and interfere constructively. They form azimuthal eigenmodes of a magnetic ring resonator which we resolve up to the fourth order. The eigenfrequencies are calculated semianalytically and classified as a function of magnetic field by a quantization rule which takes into account a periodic boundary condition. Strikingly each mode exists only below a characteristic field.