Kinetics of Topological Stone-Wales Defect Formation in Single Walled Carbon

Topological Stone-Wales defect in carbon nanotubes plays a central role in plastic deformation, chemical functionalization, and superstructure formation. Here, we systematically investigate the formation kinetics of such defects within density functional approach coupled with the transition state theory. We find that both the formation and activation energies depend critically on the nanotube chairality, diameter, and defect orientation. The microscopic origin of the observed dependence is explained with curvature induced rehybridization in nanotube. Surprisingly, the kinetic barrier follows an empirical Br{\o}nsted-Evans-Polanyi type correlation with the corresponding formation energy, and can be understood in terms of overlap between energy-coordinate parabolas representing the structures with and without the defect. Further, we propose a possible route to substantially decrease the kinetic activation barrier. Such accelerated rates of defect formation are desirable in many novel electronic, mechanical and chemical applications, and also facilitate the formation of three-dimensional nanotube superstructures.Comment: 10 pages, Supporting information, The Journal of Physical Chemistry C (2015

Portfolio Return Characteristics of Different Industries

Over the last decade we have witnessed the rise and fall of theso-called new economy stocks. One central question is to what extentthese new firms differ from traditional firms. Empirical evidencesuggests that stock returns are not normally distributed. In thisarticle we investigate whether this also holds for portfolios ofstocks from a growth industry. Furthermore, we will compare this typeof portfolios with portfolios of stocks from a more traditionalindustry. Usually, only value weighted and equally weighted portfoliosare used to describe and compare portfolio return characteristics.Instead, in our analysis, we use a novel approach in which we use aninfinite number of portfolios that together represent the set of allfeasible portfolio opportunities.performance evaluation;portfolio management;investments;stock markets;sector index

Object oriented design of a thermo-mechanical FEM code

An object oriented design is presented for a computer program that can perform\ud thermo-mechanically coupled analyzes. The target of the design is a \ud exible and robust\ud computer program. It should be easy to adapt and extend, re-using existing code, without\ud interfering with already established algorithms.\ud The program uses publicly available toolkits that are currently emerging as C++ pack-\ud ages. First of all the Standard C++ Library (formerly Standard Template Library) is\ud used for packing items in container classes. Secondly the matrix and vector operations\ud are derived from the Template Numerical Toolkit (TNT) and �nally (not essentially for\ud the numerical part) a graphical user interface is made, based on the wxWindows package,\ud that can generate a GUI for Motif and MS-Windows with the same code.\ud Attention is given to the design of classes such as speci�c elements and material classes\ud based on more general classes. A hierarchy of classes is constructed where general behavior\ud is put high in the hierarchy and speci�c behavior low. The choice between inheritance and\ud aggregation is made at several levels

Pan-European backcasting exercise, enriched with regional perspective, and including a list of short-term policy options

This deliverable reports on the results of the third and final pan-European stakeholder meeting and secondly, on the enrichment with a Pilot Area and regional perspective. The main emphasis is on backcasting as a means to arrive at long-term strategies and short-term (policy) actions

Mechanical fluidity of fully suspended biological cells

Mechanical characteristics of single biological cells are used to identify and possibly leverage interesting differences among cells or cell populations. Fluidity---hysteresivity normalized to the extremes of an elastic solid or a viscous liquid---can be extracted from, and compared among, multiple rheological measurements of cells: creep compliance vs. time, complex modulus vs. frequency, and phase lag vs. frequency. With multiple strategies available for acquisition of this nondimensional property, fluidity may serve as a useful and robust parameter for distinguishing cell populations, and for understanding the physical origins of deformability in soft matter. Here, for three disparate eukaryotic cell types deformed in the suspended state via optical stretching, we examine the dependence of fluidity on chemical and environmental influences around a time scale of 1 s. We find that fluidity estimates are consistent in the time and the frequency domains under a structural damping (power-law or fractional derivative)model, but not under an equivalent-complexity lumpedcomponent (spring-dashpot) model; the latter predicts spurious time constants. Although fluidity is suppressed by chemical crosslinking, we find that adenosine triphosphate (ATP) depletion in the cell does not measurably alter the parameter, and thus conclude that active ATP-driven events are not a crucial enabler of fluidity during linear viscoelastic deformation of a suspended cell. Finally, by using the capacity of optical stretching to produce near-instantaneous increases in cell temperature, we establish that fluidity increases with temperature---now measured in a fully suspended, sortable cell without the complicating factor of cell-substratum adhesion

Cosmic-ray energy spectrum and composition up to the ankle - the case for a second Galactic component

We have carried out a detailed study to understand the observed energy spectrum and composition of cosmic rays with energies up to ~10^18 eV. Our study shows that a single Galactic component with subsequent energy cut-offs in the individual spectra of different elements, optimised to explain the observed spectra below ~10^14 eV and the knee in the all-particle spectrum, cannot explain the observed all-particle spectrum above ~2x10^16 eV. We discuss two approaches for a second component of Galactic cosmic rays -- re-acceleration at a Galactic wind termination shock, and supernova explosions of Wolf-Rayet stars, and show that the latter scenario can explain almost all observed features in the all-particle spectrum and the composition up to ~10^18 eV, when combined with a canonical extra-galactic spectrum expected from strong radio galaxies or a source population with similar cosmological evolution. In this two-component Galactic model, the knee at ~ 3x10^15 eV and the second knee at ~10^17 eV in the all-particle spectrum are due to the cut-offs in the first and second components, respectively. We also discuss several variations of the extra-galactic component, from a minimal contribution to scenarios with a significant component below the ankle (at ~4x10^18 eV), and find that extra-galactic contributions in excess of regular source evolution are neither indicated nor in conflict with the existing data. Our main result is that the second Galactic component predicts a composition of Galactic cosmic rays at and above the second knee that largely consists of helium or a mixture of helium and CNO nuclei, with a weak or essentially vanishing iron fraction, in contrast to most common assumptions. This prediction is in agreement with new measurements from LOFAR and the Pierre Auger Observatory which indicate a strong light component and a rather low iron fraction between ~10^17 and 10^18 eV.Comment: Added Table 4; Published in A&A, 595 (2016) A33 (Highlight paper

Observations of the J = 2→1 transitions of ¹²C¹⁶O and ¹²C¹⁸O towards galactic H II regions

Observations are reported of the J = 2→1 transitions of CO and 12C18O at 230 and 219 GHz respectively from a number of galactic sources. A map of the central 1/2° × 1/2° of the Orion A molecular cloud is presented. The spectra are interpreted to derive molecular densities and abundance ratios in the molecular clouds observed

Enhancement of quasiparticle recombination in Ta and Al superconductors by implantation of magnetic and nonmagnetic atoms

The quasiparticle recombination time in superconducting films, consisting of the standard electron-phonon interaction and a yet to be identified low temperature process, is studied for different densities of magnetic and nonmagnetic atoms. For both Ta and Al, implanted with Mn, Ta and Al, we observe an increase of the recombination rate. We conclude that the enhancement of recombination is not due to the magnetic moment, but arises from an enhancement of disorder.Comment: 4 pages, 4 figure