Interaction-induced backscattering in short quantum wires

We study interaction-induced backscattering in clean quantum wires with adiabatic contacts exposed to a voltage bias. Particle backscattering relaxes such systems to a fully equilibrated steady state only on length scales exponentially large in the ratio of bandwidth of excitations and temperature. Here we focus on shorter wires in which full equilibration is not accomplished. Signatures of relaxation then are due to backscattering of hole excitations close to the band bottom which perform a diffusive motion in momentum space while scattering from excitations at the Fermi level. This is reminiscent to the first passage problem of a Brownian particle and, regardless of the interaction strength, can be described by an inhomogeneous Fokker-Planck equation. From general solutions of the latter we calculate the hole backscattering rate for different wire lengths and discuss the resulting length dependence of interaction-induced correction to the conductance of a clean single channel quantum wire.Comment: 10 pages, 4 figure

Scattering of rare-gas atoms at a metal surface: evidence of anticorrugation of the helium-atom potential-energy surface and the surface electron density

Recent measurements of the scattering of He and Ne atoms at Rh(110) suggest that these two rare-gas atoms measure a qualitatively different surface corrugation: While Ne atom scattering seemingly reflects the electron-density undulation of the substrate surface, the scattering potential of He atoms appears to be anticorrugated. An understanding of this perplexing result is lacking. In this paper we present density functional theory calculations of the interaction potentials of He and Ne with Rh(110). We find that, and explain why, the nature of the interaction of the two probe particles is qualitatively different, which implies that the topographies of their scattering potentials are indeed anticorrugated.Comment: RevTeX, 4 pages, 10 figure

Integrated care at the crossroads—defining the way forward

Introduction and background: The non-existence of a common terminology or standards in Integrated Care makes it difficult to compare experiences and results, whether on a national or international level, while the interdisciplinarity of the concept, both in theory and practice, proves to be a curse when it should be a blessing. Thus, we found it high time to bridge the gap, bring practice to theory and discuss the pressing issues of future Integrated Care research. <br><br> Workshop report: During the expert workshop, discussions were held concerning four overarching topics: (1) defining the common base for integrated care, evaluation and quality; (2) discussion on methods and tools, healthy environs; (3) governing and managerial prerequisites for integrated care and the future of integrated care; and (4) research questions arising from the workshop. The results were formulated into actions and research questions for the future. <br><br> Discussion: The workshop proved the necessity of consolidation in the area in order to foment the concept. Researchers should improve coordination and cooperation among themselves and draw from the various fields which deal with similar questions. <br><br> Conclusion: It remains to be seen whether integrated care manages to grow out of its baby shoes and establish itself as an independent and interdisciplinary field of research

The formation of young massive clusters by colliding flows

Young massive clusters (YMCs) are the most intense regions of star formation in galaxies. Formulating a model for YMC formation whilst at the same time meeting the constraints from observations is highly challenging however. We show that forming YMCs requires clouds with densities $\gtrsim$ 100 cm$^{-3}$ to collide with high velocities ($\gtrsim$ 20 km s$^{-1}$). We present the first simulations which, starting from moderate cloud densities of $\sim100$ cm$^{-3}$, are able to convert a large amount of mass into stars over a time period of around 1 Myr, to produce dense massive clusters similar to those observed. Such conditions are commonplace in more extreme environments, where YMCs are common, but atypical for our Galaxy, where YMCs are rare.Comment: 6 pages, 5 figures, accepted for publication in MNRAS Letter

Prioritising integrated care initiatives on a national level. Experiences from Austria

Introduction and background: Based on a policy initiative and the foundation of the Competence Centre for Integrated Care by the Austrian Social Security Institutions in 2006, the aim of the project was to identify and prioritise potential diseases and target groups for which integrated care models should be developed and implemented within the Austrian health system. The project was conducted as a cooperation between the Competence Centre for Integrated Care of the Viennese Health Insurance Fund and the Institute of Social Medicine of the Medical University Vienna to ensure the involvement of both, theory and practice. <br><br> Project report: The focus of the project was to develop an evidence-based process for the identification and prioritisation of diseases and target groups for integrated care measures. As there was no evidence of similar projects elsewhere, the team set out to design the prioritisation process and formulate the selection criteria based on the work in a focus group, literature reviews and a scientific council of national and international experts. The method and criteria were evaluated by an expert workshop. <br><br> Discussion: The active involvement of all stakeholders from the beginning was crucial for the success. The time constraint proved also beneficial since it allowed the project team to demand focus and cooperation from all experts and stakeholders included. <br><br> Conclusion: Our experience demonstrates that, with a clear concept and model, an evidence-based prioritisation including all stakeholders can be achieved. Ultimately however, the prioritisation is a political discussion and decision. Our model can only help base these decisions on sound and reasonable assumptions

Transport in the XX chain at zero temperature: Emergence of flat magnetization profiles

We study the connection between magnetization transport and magnetization profiles in zero-temperature XX chains. The time evolution of the transverse magnetization, m(x,t), is calculated using an inhomogeneous initial state that is the ground state at fixed magnetization but with m reversed from -m_0 for x0. In the long-time limit, the magnetization evolves into a scaling form m(x,t)=P(x/t) and the profile develops a flat part (m=P=0) in the |x/t|1/2 while it expands with the maximum velocity, c_0=1, for m_0->0. The states emerging in the scaling limit are compared to those of a homogeneous system where the same magnetization current is driven by a bulk field, and we find that the expectation values of various quantities (energy, occupation number in the fermionic representation) agree in the two systems.Comment: RevTex, 8 pages, 3 ps figure

Anomalous thermal conductivity and local temperature distribution on harmonic Fibonacci chains

The harmonic Fibonacci chain, which is one of a quasiperiodic chain constructed with a recursion relation, has a singular continuous frequency-spectrum and critical eigenstates. The validity of the Fourier law is examined for the harmonic Fibonacci chain with stochastic heat baths at both ends by investigating the system size N dependence of the heat current J and the local temperature distribution. It is shown that J asymptotically behaves as (ln N)^{-1} and the local temperature strongly oscillates along the chain. These results indicate that the Fourier law does not hold on the harmonic Fibonacci chain. Furthermore the local temperature exhibits two different distribution according to the generation of the Fibonacci chain, i.e., the local temperature distribution does not have a definite form in the thermodynamic limit. The relations between N-dependence of J and the frequency-spectrum, and between the local temperature and critical eigenstates are discussed.Comment: 10 pages, 4 figures, submitted to J. Phys.: Cond. Ma