Counting function for a sphere of anisotropic quartz

We calculate the leading Weyl term of the counting function for a mono-crystalline quartz sphere. In contrast to other studies of counting functions, the anisotropy of quartz is a crucial element in our investigation. Hence, we do not obtain a simple analytical form, but we carry out a numerical evaluation. To this end we employ the Radon transform representation of the Green's function. We compare our result to a previously measured unique data set of several tens of thousands of resonances.Comment: 16 pages, 11 figure

Highly Dispersive Electron Relaxation and Colossal Thermoelectricity in the Correlated Semiconductor FeSb2_2

We show that the colossal thermoelectric power, $S(T)$, observed in the correlated semiconductor FeSb$_2$ below 30\,K is accompanied by a huge Nernst coefficient $\nu(T)$ and magnetoresistance MR$(T)$. Markedly, the latter two quantities are enhanced in a strikingly similar manner. While in the same temperature range, $S(T)$ of the reference compound FeAs$_2$, which has a seven-times larger energy gap, amounts to nearly half of that of FeSb$_2$, its $\nu(T)$ and MR$(T)$ are intrinsically different to FeSb$_2$: they are smaller by two orders of magnitude and have no common features. With the charge transport of FeAs$_2$ successfully captured by the density functional theory, we emphasize a significantly dispersive electron-relaxation time $\tau(\epsilon_k)$ due to electron-electron correlations to be at the heart of the peculiar thermoelectricity and magnetoresistance of FeSb$_2$.Comment: 8 pages, 5 figure

Collision of One-Dimensional Nonlinear Chains

We investigate one-dimensional collisions of unharmonic chains and a rigid wall. We find that the coefficient of restitution (COR) is strongly dependent on the velocity of colliding chains and has a minimum value at a certain velocity. The relationship between COR and collision velocity is derived for low-velocity collisions using perturbation methods. We found that the velocity dependence is characterized by the exponent of the lowest unharmonic term of interparticle potential energy

A study of the fine scale motions of incompressible time-developing mixing layers

This work is an extension of a project conducted at the previous CTR summer program and was reported by Chen et al. (1990). In that program, the geometry and topology of the dissipating motions in a variety of shear flows was examined. All data was produced by direct numerical simulations (DNS). The partial derivatives of the velocity field were determined at every grid point in the flow and various invariants and related quantities were computed from the velocity gradient tensor. Motions characterized by high rates of kinetic energy dissipation and high enstrophy were of particular interest. Scatter diagrams of the invariants were mapped out and interesting and unexpected patterns were seen. Each type of shear layer produced its own characteristic scatter plot. In the present project, attention is focused on the incompressible plane mixing layer, and the scatter diagrams are replaced with more useful joint probability density contours. Comparison of the topology of the dissipating motions of flows at different Reynolds numbers are made. Also, plane mixing layers at the same Reynolds number but with different initial conditions are compared

ATscale – Establishing a Cross-Sector Partnership to Increase Access to Assistive Technology

Given existing gaps in access to Assistive Technology (AT) globally, it is important to think broadly and identify innovative approaches to overcome them. After an initial scoping in 2018, involving consultations and landscape analyses, ATscale, the Global Partnership for Assistive Technology was launched at the Global Disability Summit in July 2018 with the aim of reaching 500 million more people with life-changing AT by 2030. Applying lessons-learned from other areas of global health and development, ATscale was established with the recognition that to influence the complex systems for AT access, a broad set of stakeholders is needed to invest in and coordinate a multifaceted, systematic approach spanning market shaping, capacity development, and political prioritisation. Already, ATscale has demonstrated how a multi-sector group can come together and develop a cohesive strategy. This strategy overview has been released and shared broadly for additional consultation and feedback to further refine ATscale’s approach moving forward. ATscale has captured the attention of a diverse set of stakeholders. It now has eleven organisations within the Forming Committee and a broad community willing to inform its development. Now that it has been established, ATscale is working to move from an initial forming phase to a more formal organisation and to refine its operating model by late 2019 or early 2020. While there is significant momentum towards taking new, innovative approaches to address the gaps in access to quality, affordable AT for all, research shows that a wide range of systemic, underlying barriers and cross-cutting factors are contributing to the challenge in matching appropriate supply and demand for AT. While ATscale will address many of these, it is also going to require partnership on multiple levels with a coordinated strategic approach across a variety of stakeholders. This collective effort will enable the global community to have an impact greater than the sum of its individual parts in improving access to affordable, appropriate AT globally

Analyzing Array Manipulating Programs by Program Transformation

We explore a transformational approach to the problem of verifying simple array-manipulating programs. Traditionally, verification of such programs requires intricate analysis machinery to reason with universally quantified statements about symbolic array segments, such as "every data item stored in the segment A[i] to A[j] is equal to the corresponding item stored in the segment B[i] to B[j]." We define a simple abstract machine which allows for set-valued variables and we show how to translate programs with array operations to array-free code for this machine. For the purpose of program analysis, the translated program remains faithful to the semantics of array manipulation. Based on our implementation in LLVM, we evaluate the approach with respect to its ability to extract useful invariants and the cost in terms of code size

Percutaneous transfemoral-transseptal implantation of a second-generation CardiAQ™ mitral valve bioprosthesis: first procedure description and 30-day follow-up

Transcatheter mitral valve implantation for mitral valve regurgitation is in the very early phase of development because of challenging anatomy and device dimensions. We describe the procedure of a transfemoral-transseptal implantation of the second-generation CardiAQ™ mitral valve bioprosthesis and 30-day follow-up