Approximation on partially ordered sets of regular grids

In this paper we analyse the approximation of functions on partially ordered sequences of regular grids. We start with the formulation of minimal requirements for useful grid transfer operators in such a partially ordered context, and we continue with the introduction of hierarchical decompositions and the identification of piecewise constant and piecewise linear approximations as special instances of the tensor product case. In the second part of the paper we derive error estimates for approximation in different norms on more-dimensional dyadic sequences of regular and sparse grids. We give special attention to a convenient notation

An instrument to measure atmospheric pressure fluctuations above surface gravity waves

This paper describes an instrument which has been used successfully at a field site in the Bight of Abaco, Bahamas, to monitor the atmospheric pressure field above surface gravity waves in the frequency range .5 to 5. rad/s. The atmospheric pressure is sampled at fixed elevations with a cone-shaped probe having a pressure coefficient of less than .02 magnitude for angles of attack less than 15°; the probe is mounted on a vane to minimize horizontal angles of attack. The pressure signal is conducted to a subsurface transducer through a mercury-sealed bearing. Overall system noise is estimated to be of order .5 µbars and is largely wave-incoherent

HOMO–HOMO Electron Transfer : An Elegant Strategy for p-Type Doping of Polymer Semiconductors toward Thermoelectric Applications

Unlike the conventional p‐doping of organic semiconductors (OSCs) using acceptors, here, an efficient doping concept for diketopyrrolopyrrole‐based polymer PDPP[T]$_{2}$‐EDOT (OSC‐1) is presented using an oxidized p‐type semiconductor, Spiro‐OMeTAD(TFSI)$_{2}$ (OSC‐2), exploiting electron transfer from HOMO$_{OSC-1}$ to HOMO$_{OSC-2}$. A shift of work function toward the HOMO$_{OSC-1}$ upon doping is confirmed by ultraviolet photoelectron spectroscopy (UPS). Detailed X‐ray photoelectron spectroscopy (XPS) and UV–vis–NIR absorption studies confirm HOMO$_{OSC-1}$ to HOMO$_{OSC-2}$ electron transfer. The reduction products of Spiro‐OMeTAD(TFSI)$_{2}$ to Spiro‐OMeTAD(TFSI) and Spiro‐OMeTAD is also confirmed and their relative amounts in doped samples is determined. Mott–Schottky analysis shows two orders of magnitude increase in free charge carrier density and one order of magnitude increase in the charge carrier mobility. The conductivity increases considerably by four orders of magnitude to a maximum of 10 S m$^{-1}$ for a very low doping ratio of 8 mol%. The doped polymer films exhibit high thermal and ambient stability resulting in a maximum power factor of 0.07 µW m$^{-1}$ K$^{-2}$ at a Seebeck coefficient of 140 µV K$^{-1}$ for a very low doping ratio of 4 mol%. Also, the concept of HOMO$_{OSC-1}$ to HOMO$_{OSC-2}$ electron transfer is a highly efficient, stable and generic way to p‐dope other conjugated polymers

Toeplitz operators on symplectic manifolds

We study the Berezin-Toeplitz quantization on symplectic manifolds making use of the full off-diagonal asymptotic expansion of the Bergman kernel. We give also a characterization of Toeplitz operators in terms of their asymptotic expansion. The semi-classical limit properties of the Berezin-Toeplitz quantization for non-compact manifolds and orbifolds are also established.Comment: 40 page

A variant of the Mukai pairing via deformation quantization

We give a new method to prove a formula computing a variant of Caldararu's Mukai pairing \cite{Cal1}. Our method is based on some important results in the area of deformation quantization. In particular, part of the work of Kashiwara and Schapira in \cite{KS} as well as an algebraic index theorem of Bressler, Nest and Tsygan in \cite{BNT},\cite{BNT1} and \cite{BNT2} are used. It is hoped that our method is useful for generalization to settings involving certain singular varieties.Comment: 8 pages. Comments and suggestions welcom

Gauge Orbit Types for Theories with Classical Compact Gauge Group

We determine the orbit types of the action of the group of local gauge transformations on the space of connections in a principal bundle with structure group O(n), SO(n) or $Sp(n)$ over a closed, simply connected manifold of dimension 4. Complemented with earlier results on U(n) and SU(n) this completes the classification of the orbit types for all classical compact gauge groups over such space-time manifolds. On the way we derive the classification of principal bundles with structure group SO(n) over these manifolds and the Howe subgroups of SO(n).Comment: 57 page

Structural Transitions and Global Minima of Sodium Chloride Clusters

In recent experiments on sodium chloride clusters structural transitions between nanocrystals with different cuboidal shapes were detected. Here we determine reaction pathways between the low energy isomers of one of these clusters, (NaCl)35Cl-. The key process in these structural transitions is a highly cooperative rearrangement in which two parts of the nanocrystal slip past one another on a {110} plane in a direction. In this way the nanocrystals can plastically deform, in contrast to the brittle behaviour of bulk sodium chloride crystals at the same temperatures; the nanocrystals have mechanical properties which are a unique feature of their finite size. We also report and compare the global potential energy minima for (NaCl)NCl- using two empirical potentials, and comment on the effect of polarization.Comment: extended version, 13 pages, 8 figures, revte

The Inverse Ocean Modeling System. Part I: Implementation

The Inverse Ocean Modeling (IOM) system constructs and runs weak-constraint, four-dimensional variational data assimilation (W4DVAR) for any dynamical model and any observing array. The dynamics and the observing algorithms may be nonlinear but must be functionally smooth. The user need only provide the model and the observing algorithms, together with an interpolation scheme that relates the model numerics to the observer’s coordinates. All other model-dependent elements of the Inverse Ocean Modeling assimilation algorithm (see both Chua and Bennett), including adjoint generators and Monte Carlo estimates of posteriors, have been derived and coded as templates in Parametric FORTRAN (Erwig et al.). This language has been developed for the IOM but has wider application in scientific programming. Guided by the Parametric FORTRAN templates, and by model information entered via a graphical user interface (GUI), the IOM generates conventional FORTRAN code for each of the many algorithm elements, customized to the user’s model. The IOM also runs the various W4DVAR assimilations, which are monitored by the GUI. The system is supported by a Web site that includes interactive tutorials for the assimilation algorithm.Keywords: Data assimilation, Ocean models, Variational analysi

Effect of Impurities on Pentacene Thin Film Growth for Field-Effect Transistors

Pentacenequinone (PnQ) impurities have been introduced into a pentacene source material at number densities from 0.001 to 0.474 to quantify the relative effects of impurity content and grain boundary structure on transport in pentacene thin-film transistors. Atomic force microscopy (AFM) and electrical measurements of top-contact pentacene thin-film transistors have been employed to directly correlate initial structure and final film structures, with the device mobility as a function of added impurity content. The results reveal a factor four decrease in mobility without significant changes in film morphology for source PnQ number fractions below ~0.008. For these low concentrations, the impurity thus directly influences transport, either as homogeneously distributed defects or by concentration at the otherwise-unchanged grain boundaries. For larger impurity concentrations, the continuing strong decrease in mobility is correlated with decreasing grain size, indicating an impurity-induced increase in the nucleation of grains during early stages of film growth.Comment: 18 pages, 4 Figures, 1 Tabl