X-ray and neutron scattering

Abstract:

We report inelastic neutron-scattering measurements of the magnetic excitations in SrFe2As2, the parent of a family of iron-based superconductors. The data extend throughout the Brillouin zone and up to energies of ~260 meV. The spectrum calculated from a J1-J 2 model does not accurately describe our data, and we show that some of the qualitative features that the model fails to describe are readily explained by calculations from a five-band itinerant mean-field model. In particular, the high-energy part of the spectra recorded above TN do not differ significantly from those at low temperature, which is explained by the itinerant model and which has implications for theories of electronic nematic and orbital ordering. © 2011 American Physical Society.

Abstract:

Aims

To examine the demographic and workplace risk factors of serious falls and associated economic burden in Canadian health care workers.

Methods

Fall injury data during 2005-2008 from a workplace health and safety surveillance system were linked with workers' compensation claims and payroll records. The costs for treatment and wage loss and days lost for accepted time-loss claims were calculated. Demographic and work-related factors were identified to distinguish the risk for more serious falls from less serious falls.

Results

Nine hundred and thirty-eight fall injury claims were captured among 48 519 full-time equivalent workers. Workers >60 years, part time or employed in the long-term care sector sustained a higher proportion of serious falls (>70%). Over 75% of falls were serious for care aides, facility support service workers and community health workers. In the multivariate analysis, the risk of serious falls remained higher for workers in the long-term care sector [odds ratio (OR) 1.71; P < 0.05] compared with those in acute care and for care aides (OR 1.72; P < 0.05), facility support service workers (OR 2.58; P < 0.01) and community health workers (OR 3.61; P < 0.001) compared with registered nurses (RNs). The median number of days lost was higher for females, long-term care workers, licensed practical nurses and care aides. Females, long-term care workers, RNs, licensed practical nurses, care aides and maintenance workers had the most costly falls.

Conclusions

Reducing work-related serious fall injuries would be expected to bring about significant benefits in terms of reduced pain and suffering, improved workplace productivity, reduced absenteeism and reduced compensation costs.

Abstract:

We used ultrafast resonant soft x-ray diffraction to probe the picosecond dynamics of spin and orbital order in La(0.5)Sr(1.5)MnO(4) after photoexcitation with a femtosecond pulse of 1.5 eV radiation. Complete melting of antiferromagnetic spin order is evidenced by the disappearance of a (1/4,1/4,1/2) diffraction peak. On the other hand, the (1/4,1/4,0) diffraction peak, reflecting orbital order, is only partially reduced. We interpret the results as evidence of destabilization in the short-range exchange pattern with no significant relaxation of the long-range Jahn-Teller distortions. Cluster calculations are used to analyze different possible magnetically ordered states in the long-lived metastable phase. Nonthermal coupling between light and magnetism emerges as a primary aspect of photoinduced phase transitions in manganites.