Violation of non-interacting V\cal V-representability of the exact solutions of the Schr\"odinger equation for a two-electron quantum dot in a homogeneous magnetic field

We have shown by using the exact solutions for the two-electron system in a parabolic confinement and a homogeneous magnetic field [ M.Taut, J Phys.A{\bf 27}, 1045 (1994) ] that both exact densities (charge- and the paramagnetic current density) can be non-interacting $\cal V$-representable (NIVR) only in a few special cases, or equivalently, that an exact Kohn-Sham (KS) system does not always exist. All those states at non-zero $B$ can be NIVR, which are continuously connected to the singlet or triplet ground states at B=0. In more detail, for singlets (total orbital angular momentum $M_L$ is even) both densities can be NIVR if the vorticity of the exact solution vanishes. For $M_L=0$ this is trivially guaranteed because the paramagnetic current density vanishes. The vorticity based on the exact solutions for the higher $|M_L|$ does not vanish, in particular for small r. In the limit $r \to 0$ this can even be shown analytically. For triplets ($M_L$ is odd) and if we assume circular symmetry for the KS system (the same symmetry as the real system) then only the exact states with $|M_L|= 1$ can be NIVR with KS states having angular momenta $m_1=0$ and $|m_2|=1$. Without specification of the symmetry of the KS system the condition for NIVR is that the small-r-exponents of the KS states are 0 and 1.Comment: 18 pages, 4 figure

Giant thermoelectric effects in a proximity-coupled superconductor-ferromagnet device

The usually negligibly small thermoelectric effects in superconducting heterostructures can be boosted dramatically due to the simultaneous effect of spin splitting and spin filtering. Building on an idea of our earlier work [Phys. Rev. Lett. $\textbf{110}$, 047002 (2013)], we propose realistic mesoscopic setups to observe thermoelectric effects in superconductor heterostructures with ferromagnetic interfaces or terminals. We focus on the Seebeck effect being a direct measure of the local thermoelectric response and find that a thermopower of the order of $\sim200$ $\mu V/K$ can be achieved in a transistor-like structure, in which a third terminal allows to drain the thermal current. A measurement of the thermopower can furthermore be used to determine quantitatively the spin-dependent interface parameters that induce the spin splitting. For applications in nanoscale cooling we discuss the figure of merit for which we find enormous values exceeding 1 for temperature $\lesssim 1$K

The strength of the radial-breathing mode in single-walled carbon nanotubes

We show by ab initio calculations that the electron-phonon coupling matrix element M of the radial breathing mode in single-walled carbon nanotubes depends strongly on tube chirality. For nanotubes of the same diameter the coupling strength |M|^2 is up to one order of magnitude stronger for zig-zag than for armchair tubes. For (n,m) tubes M depends on the value of (n-m) mod 3, which allows to discriminate semiconducting nano tubes with similar diameter by their Raman scattering intensity. We show measured resonance Raman profiles of the radial breathing mode which support our theoretical predictions

The Socialization of Bullying Through Community College Nursing Education: A Multiple Case Study

Many recent studies propose that bullying in the workplace is prevalent and is a phenomenon which occurs in the nursing workplace as well as in nursing education. This qualitative study examined the effects of vertical bullying upon community college nursing students and graduates, and the effect of this behavior upon the socialization of those learning the nursing profession. The study is based on a theoretical framework based on the findings of Salin (2003) and Twale and De Luca (2008) adapting their theory of bullying in academia which incorporated enabling, motivating and precipitating factors leading to intensified bullying. The study investigated the effects vertical bullying has on nursing student and graduate behavior, the socialization of vertical bullying through education, and its possible connection to nursing hierarchy and the academic structure supporting bullying through nursing education

Effect of Baffle Design on the Off-bottom Suspension Characteristics of Axial-flow Impellers in a Pilot-scale Mixing Vessel

The work aimed to determine the optimum system parameters for complete particle suspension. The experiments performed in a pilot-scale vessel (D = 1 m) were focussed on a study of the effects of geometrical vessel arrangements and, above all, on the effect of alterations to the shape of the baffles. The experiments sought above all to determine the critical impeller speed, ncr, and impeller power consumption, P, in a vessel equipped with non-standard, arrow-headed baffles, and also to compare these experimental data with results arising from measurements undertaken in the same vessel, but equipped with four standard straight baffles. Three types of axial-flow impellers were investigated, each of them in two sizes. The suspension volume fraction, , varied up to 10 %, with particle diameter from 0.1 to 3 mm. The results aid the selection of the most favourable types of baffles and impeller giving the minimum power consumption and/or the minimum speed for just-suspended particles. It is shown that the installation of arrow-headed baffles appears to be energetically more advantageous compared with the standard baffling

The Geometry of the Cholesteric Phase

We propose a construction of a cholesteric pitch axis for an arbitrary nematic director field as an eigenvalue problem. Our definition leads to a Frenet-Serret description of an orthonormal triad determined by this axis, the director, and the mutually perpendicular direction. With this tool we are able to compare defect structures in cholesterics, biaxial nematics, and smectics. Though they all have similar ground state manifolds, the defect structures are different and cannot be, in general, translated from one phase to the other.Comment: 5 pages, the full catastroph

Geometry of the cholesteric phase

We propose a construction of a cholesteric pitch axis for an arbitrary nematic director field as an eigenvalue problem. Our definition leads to a Frenet-Serret description of an orthonormal triad determined by this axis, the director, and the mutually perpendicular direction. With this tool, we are able to compare defect structures in cholesterics, biaxial nematics, and smectics. Though they all have similar ground state manifolds, the defect structures are different and cannot, in general, be translated from one phase to the other

High pressure x-ray diffraction study of the volume collapse in Ba24Si100 clathrate

International audienceThe high pressure stability of the silicon type-III clathrate Ba24Si100 has been studied by x-ray diffraction (XRD) up to a maximum pressure of 37.4 GPa. The high pressure behavior of this Si type-III clathrate appears to be analogous to the structural type-I parent Ba8Si46. An isostructural volume collapse is observed at ~23 GPa, a value higher than for Ba8Si46 (13-15 GPa). The crystallinity of the structure is preserved up to the maximum attained pressure without amorphization, which appears to be in contradiction with the interpretation given in a Raman spectroscopy study [Shimizu et al., Phys. Rev. B 71, 094108 (2005)]. Nevertheless, the XRD analysis shows the appearance of a type-III disordered nanocaged-based crystalline structure after the volume collapse. Moreover, we find that the volume collapse transformation is (quasi)reversible after pressure release. Additionally, a low pressure transition first evidenced by Raman spectroscopy is also observed in our XRD study at 5 GPa: The variation of the isotropic thermal factors of Ba atoms shows a clear discontinuity at this pressure while the average positions of Ba atoms remain identical

(Syn)aesthetics and disturbance : tracing a transgressive style

An examination and exploration of ‘the (syn)aesthetic style’, a particular sensate mode of performance and appreciation that has become prominent in recent years in contemporary arts practice. The (syn)aesthetic performance style fuses disciplines and techniques to create interdisciplinary and intersensual work with emphasis upon; the (syn)aesthetic hybrid; the prioritisation of the body in performance and the visceral-verbal ‘play-text’. ‘(Syn)aesthetics’ is adopted as an original discourse for the analysis of such work, appropriating certain quintessential features of the physiological condition of synaesthesia to clarify the impulse in performance and appreciation which affects a ‘disturbance’ within audience interpretation. Original terms employed attempt to elucidate the complex appreciation strategies integral to this performance experience. These include the double-edged semantic/somatic or making-sense/sense-making process of appreciation, which embraces the individual, immediate and innate, and the ‘corporeal memory’ of the perceiving body. Liveness and the live(d) moment are considered, alongside notions of ritual and transcendence and the primordial and technological. The argument surveys the inheritance that saw to this contemporary style emerging, in Britain in particular, considering female performance practice, intercultural and interdisciplinary ensemble performance and the ‘New Writing’ aesthetic. Critical and performance theorists referred to include Friedrich Nietzsche, the Russian Formalists, Roland Barthes, Julia Kristeva, Hélène Cixous, Luce Irigaray, Antonin Artaud, Valère Novarina, Howard Barker and Susan Broadhurst. Contemporary practitioners highlighted as case studies exemplary of (syn)aesthetic practice are Sara Giddens, Marisa Carnesky, Caryl Churchill and Sarah Kane. Furthermore, documentation of a series of original performance workshops explores the (syn)aesthetic impulse in performance and analysis from the perspectives of writer, performer and audience. (Syn)aesthetics as an interpretative device endeavours to enhance understanding of the intangible areas of performance which are increasingly difficult to articulate, thereby presenting a mode of analysis that extends performance theory for students and practitioners within the arts.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Pressure-induced polyamorphism in TiO2 nanoparticles

Machon, Denis Daniel, Marlene Pischedda, Vittoria Daniele, Stephane Bouvier, Pierre LeFloch, SylvieTwo different nanometric (6 nm) TiO2 compounds, anatase polycrystals and amorphous particles, were investigated under high pressure using Raman spectroscopy. Nanoanatase undergoes a pressure-induced amorphization. The pressure-induced transformations of this mechanically prepared amorphous state are compared with those of a chemically prepared amorphous particles. In the mechanically prepared amorphous state, a reversible transformation from a low-density amorphous state to high-density amorphous state (HDA1) is observed in the range 13-16 GPa. In the chemically prepared sample, a transformation to a new high-density amorphous state (HDA2) is observed at around 21 GPa. Further compression leads to the transformation HDA2 -> HDA1 at similar to 30 GPa. We demonstrate that depending on the starting amorphous material, the high-pressure polyamorphic transformations may differ. This observation indicates that pressure is a suited tool to discriminate between nanomaterials apparently similar at ambient conditions