169 research outputs found
Coherent control of orbital wavefunctions in the quantum spin liquid
Resonant driving of electronic transitions with coherent laser sources
creates quantum coherent superpositions of the involved electronic states. Most
time-resolved studies have focused on gases or isolated subsystems embedded in
insulating solids, aiming for applications in quantum information. Here, we
demonstrate coherent control of orbital wavefunctions in pyrochlore
, which forms an interacting spin liquid ground state. We
show that resonant excitation with a strong THz pulse creates a coherent
superposition of the lowest energy Tb 4f states before the magnetic
interactions eventually dephase them. The coherence manifests itself as a
macroscopic oscillating magnetic dipole, which is detected by ultrafast
resonant x-ray diffraction. The induced quantum coherence demonstrates coherent
control of orbital wave functions, a new tool for the ultrafast manipulation
and investigation of quantum materials
The ratio of horizontal to vertical displacement in solar oscillations estimated from combined SO/PHI and SDO/HMI observations
In order to make accurate inferences about the solar interior using
helioseismology, it is essential to understand all the relevant physical
effects on the observations. One effect to understand is the (complex-valued)
ratio of the horizontal to vertical displacement of the p- and f-modes at the
height at which they are observed. Unfortunately, it is impossible to measure
this ratio directly from a single vantage point, and it has been difficult to
disentangle observationally from other effects. In this paper we attempt to
measure the ratio directly using 7.5 hours of simultaneous observations from
the Polarimetric and Helioseismic Imager on board Solar Orbiter and the
Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. While
image geometry problems make it difficult to determine the exact ratio, it
appears to agree well with that expected from adiabatic oscillations in a
standard solar model. On the other hand it does not agree with a commonly used
approximation, indicating that this approximation should not be used in
helioseismic analyses. In addition, the ratio appears to be real-valued.Comment: Accepted for publication in Astronomy & Astrophysics. 8 pages, 8
figure
Intensity contrast of solar network and faculae close to the solar limb, observed from two vantage points
The brightness of faculae and network depends on the angle at which they are
observed and the magnetic flux density. Close to the limb, assessment of this
relationship has until now been hindered by the increasingly lower signal in
magnetograms. This preliminary study aims at highlighting the potential of
using simultaneous observations from different vantage points to better
determine the properties of faculae close to the limb. We use data from the
Solar Orbiter/Polarimetric and Helioseismic Imager (SO/PHI), and the Solar
Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI), recorded at
angular separation of their lines of sight at the Sun. We use
continuum intensity observed close to the limb by SO/PHI and complement it with
the co-observed from SDO/HMI, originating closer to disc centre
(as seen by SDO/HMI), thus avoiding the degradation of the magnetic field
signal near the limb. We derived the dependence of facular brightness in the
continuum on disc position and magnetic flux density from the combined
observations of SO/PHI and SDO/HMI. Compared with a single point of view, we
were able to obtain contrast values reaching closer to the limb and to lower
field strengths. We find the general dependence of the limb distance at which
the contrast is maximum on the flux density to be at large in line with single
viewpoint observations, in that the higher the flux density is, the closer the
turning point lies to the limb. There is a tendency, however, for the maximum
to be reached closer to the limb when determined from two vantage points. We
note that due to the preliminary nature of this study, these results must be
taken with caution. Our analysis shows that studies involving two viewpoints
can significantly improve the detection of faculae near the solar limb and the
determination of their brightness contrast relative to the quiet Sun
Differences across health care systems in outcome and cost-utility of surgical and conservative treatment of chronic low back pain: a study protocol
<p>Abstract</p> <p>Background</p> <p>There is little evidence on differences across health care systems in choice and outcome of the treatment of chronic low back pain (CLBP) with spinal surgery and conservative treatment as the main options. At least six randomised controlled trials comparing these two options have been performed; they show conflicting results without clear-cut evidence for superior effectiveness of any of the evaluated interventions and could not address whether treatment effect varied across patient subgroups. Cost-utility analyses display inconsistent results when comparing surgical and conservative treatment of CLBP. Due to its higher feasibility, we chose to conduct a prospective observational cohort study.</p> <p>Methods</p> <p>This study aims to examine if</p> <p>1. Differences across health care systems result in different treatment outcomes of surgical and conservative treatment of CLBP</p> <p>2. Patient characteristics (work-related, psychological factors, etc.) and co-interventions (physiotherapy, cognitive behavioural therapy, return-to-work programs, etc.) modify the outcome of treatment for CLBP</p> <p>3. Cost-utility in terms of quality-adjusted life years differs between surgical and conservative treatment of CLBP.</p> <p>This study will recruit 1000 patients from orthopaedic spine units, rehabilitation centres, and pain clinics in Switzerland and New Zealand. Effectiveness will be measured by the Oswestry Disability Index (ODI) at baseline and after six months. The change in ODI will be the primary endpoint of this study.</p> <p>Multiple linear regression models will be used, with the change in ODI from baseline to six months as the dependent variable and the type of health care system, type of treatment, patient characteristics, and co-interventions as independent variables. Interactions will be incorporated between type of treatment and different co-interventions and patient characteristics. Cost-utility will be measured with an index based on EQol-5D in combination with cost data.</p> <p>Conclusion</p> <p>This study will provide evidence if differences across health care systems in the outcome of treatment of CLBP exist. It will classify patients with CLBP into different clinical subgroups and help to identify specific target groups who might benefit from specific surgical or conservative interventions. Furthermore, cost-utility differences will be identified for different groups of patients with CLBP. Main results of this study should be replicated in future studies on CLBP.</p
IT adoption of clinical information systems in Austrian and German hospitals: results of a comparative survey with a focus on nursing
<p>Abstract</p> <p>Background</p> <p>IT adoption is a process that is influenced by different external and internal factors. This study aimed</p> <p indent="1">1. to identify similarities and differences in the prevalence of medical and nursing IT systems in Austrian and German hospitals, and</p> <p indent="1">2. to match these findings with characteristics of the two countries, in particular their healthcare system, and with features of the hospitals.</p> <p>Methods</p> <p>In 2007, all acute care hospitals in both countries received questionnaires with identical questions. 12.4% in Germany and 34.6% in Austria responded.</p> <p>Results</p> <p>The surveys revealed a consistent higher usage of nearly all clinical IT systems, especially nursing systems, but also PACS and electronic archiving systems, in Austrian than in German hospitals. These findings correspond with a significantly wider use of standardised nursing terminologies and a higher number of PC workstations on the wards (average 2.1 PCs in Germany, 3.2 PCs in Austria). Despite these differences, Austrian and German hospitals both reported a similar IT budget of 2.6% in Austria and 2.0% in Germany (median).</p> <p>Conclusions</p> <p>Despite the many similarities of the Austrian and German healthcare system there are distinct differences which may have led to a wider use of IT systems in Austrian hospitals. In nursing, the specific legal requirement to document nursing diagnoses in Austria may have stimulated the use of standardised terminologies for nursing diagnoses and the implementation of electronic nursing documentation systems. Other factors which correspond with the wider use of clinical IT systems in Austria are: good infrastructure of medical-technical devices, rigorous organisational changes which had led to leaner processes and to a lower length of stay, and finally a more IT friendly climate. As country size is the most pronounced difference between Germany and Austria it could be that smaller countries, such as Austria, are more ready to translate innovation into practice.</p
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