Andreev reflection at point contacts with heavy-fermion UBe13 ?

We comment on a recent Letter by Waelti et al. (PRL 84, 5616 (2000)) on 'Spectroscopic evidence for unconventional superconductivity in UBe13'. We show - by using the basic Wexler formula - that it is unlikely to observe Andreev reflection at point contacts between UBe13 and a normal metal. The large superconducting anomalies usually found for those contacts are mainly due to the resistive Maxwell resistance vanishing below Tc of UBe13.Comment: 1 page, no figures, RevTeX, submitted to Phys. Rev. Let

Lorentz shear modulus of fractional quantum Hall states

We show that the Lorentz shear modulus of macroscopically homogeneous electronic states in the lowest Landau level is proportional to the bulk modulus of an equivalent system of interacting classical particles in the thermodynamic limit. Making use of this correspondence we calculate the Lorentz shear modulus of Laughlin's fractional quantum Hall states at filling factor $\nu=1/m$ ($m$ an odd integer) and find that it is equal to $\pm \hbar mn/4$, where $n$ is the density of particles and the sign depends on the direction of magnetic field. This is in agreement with the recent result obtained by Read in arXiv:0805.2507 and corrects our previous result published in Phys. Rev. B {\bf 76}, 161305 (R) (2007).Comment: 8 pages, 3 figure

Ex-vivo and early clinical results using a new pullback atherectomy catheter (PAC)

Digitalitzat per Artypla

Design and performance of ropes for climbing and sailing

Ropes are an important part of the equipment used by climbers, mountaineers, and sailors. On first inspection, most modern polymer ropes appear similar, and it might be assumed that their designs, construction, and properties are governed by the same requirements. In reality, the properties required of climbing ropes are dominated by the requirement that they effectively absorb and dissipate the energy of the falling climber, in a manner that it does not transmit more than a critical amount of force to his body. This requirement is met by the use of ropes with relatively low longitudinal stiffness. In contrast, most sailing ropes require high stiffness values to maximize their effectiveness and enable sailors to control sails and equipment precisely. These conflicting requirements led to the use of different classes of materials and different construction methods for the two sports. This paper reviews in detail the use of ropes, the properties required, manufacturing techniques and materials utilized, and the effect of service conditions on the performance of ropes. A survey of research that has been carried out in the field reveals what progress has been made in the development of these essential components and identifies where further work may yield benefits in the future

"Beat" patterns for the odd-even staggering in octupole bands from a quadrupole-octupole Hamiltonian

We propose a collective Hamiltonian which incorporates the standard quadrupole terms, octupole terms classified according to the irreducible representations of the octahedron group, a quadrupole-octupole interaction, as well as a term for the bandhead energy linear in K (the projection of angular momentum on the body-fixed z-axis). The energy is subsequently minimized with respect to K for each given value of the angular momentum I, resulting in K values increasing with I within each band, even in the case in which K is restricted to a set of microscopically plausible values. We demonstrate that this Hamiltonian is able to reproduce a variety of ``beat'' patterns observed recently for the odd-even staggering in octupole bands of light actinides.Comment: LaTeX, 20 pages plus 12 figures given in separate .ps file

Magnus and Iordanskii Forces in Superfluids

The total transverse force acting on a quantized vortex in a superfluid is a problem that has eluded a complete understanding for more than three decades. In this letter I propose a remarkably simple argument, somewhat reminiscent of Laughlin's beautiful argument for the quantization of conductance in the quantum Hall effect, to define the superfluid velocity part of the transverse force. This term is found to be $- \rho_s {\kappa}_s \times {v}_s$. Although this result does not seem to be overly controversial, this thermodynamic argument based only on macroscopic properties of the superfluid does offer a robust derivation. A recent publication by Thouless, Ao and Niu has demonstrated that the vortex velocity part of the transverse force in a homogeneous neutral superfluid is given by the usual form $\rho_s {\kappa}_s \times {v}_V$. A combination of these two independent results and the required Galilean invariance yields that there cannot be any transverse force proportional to the normal fluid velocity, in apparent conflict with Iordanskii's theory of the transverse force due to phonon scattering by the vortex.Comment: RevTex, 1 Encapsulated Postscript figur

Developing a Data Dashboard Framework for Population Health Surveillance: Widening Access to Clinical Trial Findings

Background: Population surveillance sites generate many datasets relevant to disease surveillance. However, there is a risk that these data are underutilized because of the volumes of data gathered and the lack of means to quickly disseminate analysis. Data visualization offers a means to quickly disseminate, understand, and interpret datasets, facilitating evidence-driven decision making through increased access to information. Objectives: This paper describes the development and evaluation of a framework for data dashboard design, to visualize datasets produced at a demographic health surveillance site. The aim of this research was to produce a comprehensive, reusable, and scalable dashboard design framework to fit the unique requirements of the context. Methods: The framework was developed and implemented at a demographic surveillance platform at the Africa Health Research Institute, in KwaZulu-Natal, South Africa. This context represents an exemplar implementation for the use of data dashboards within a population health-monitoring setting. Before the full launch, an evaluation study was undertaken to assess the effectiveness of the dashboard framework as a data communication and decision-making tool. The evaluation included a quantitative task evaluation to assess usability and a qualitative questionnaire exploring the attitudes to the use of dashboards. Results: The evaluation participants were drawn from a diverse group of users working at the site (n=20), comprising of community members, nurses, scientific and operational staff. Evaluation demonstrated high usability for the dashboard across user groups, with scientific and operational staff having minimal issues in completing tasks. There were notable differences in the efficiency of task completion among user groups, indicating varying familiarity with data visualization. The majority of users felt that the dashboards provided a clear understanding of the datasets presented and had a positive attitude to their increased use. Conclusions: Overall, this exploratory study indicates the viability of the data dashboard framework in communicating data trends within population surveillance setting. The usability differences among the user groups discovered during the evaluation demonstrate the need for the user-led design of dashboards in this context, addressing heterogeneous computer and visualization literacy present among the diverse potential users present in such settings. The questionnaire highlighted the enthusiasm for increased access to datasets from all stakeholders highlighting the potential of dashboards in this context