Promotion of deep tunneling through molecular barriers by electronic-nuclear coupling

Deep electronic tunneling through molecular barriers in donor-bridge-acceptor complexes is studied using an analytically solvable model. The effective tunneling matrix element is formulated as a sum over vibronic tunneling pathways. For a symmetric system the frequency of tunneling oscillations is shown to increase with the strength of electronic-nuclear coupling at the bridge, the number of electronic-nuclear coupling sites, or the frequency of a bridge vibration. Acceleration by several orders of magnitude is demonstrated within the range of realistic molecular parameters.     

Infrared Spectroscopic and Gravimetric Studies on the Dicyclopentylaminemetal(II) Tetracyanonickellate(II) Host–Aromatic Guest Systems

The host complexes M(Cyclopentylamine)₂Ni(CN)₄ (M=Co or Cd) havebeen prepared in powder form. The spectral data suggest that the structures of thesecompounds are similar to those of the Hofmann-dma-type hosts. The absorptionand the liberation processes of the aromatic guests (benzene, toluene, 1,2-, 1,3-,1,4-dichlorobenzene, 1,4-dibromobenzene o-, m-, p-xylene, naphthalene)in these hosts have been examined at room temperature by gravimetric and spectroscopicmeasurements. The desorption of the benzene guest against time has been measured. Thehost structures do not change on inclusion and liberation of the guests. The host compoundshave been suggested as sorbents for isomeric separations.     

A Generalization of Fibonacci and Lucas Quaternions

In this paper, we give a generalization of the Fibonacci and Lucas quaternions. We obtain the Binet formulas, generating functions, and some certain identities for these quaternions which include generalizations of some results of Halici.     

Synthesis of corrosion preventive long-chain <Emphasis Type="Italic">N</Emphasis>-alkyl-2-(phenylthio)-acetohydrazides and 2-oxo-2-phenylethyl-2-alkanoylhydrazinecarbodithioates

Long-chain N-alkyl-2-(phenylthio)acetohydrazides were synthesized via the reactions of 2-(phenylthio)acetohydrazide with long-straight-chain aldehydes and then reduction with sodium borohydride. The reactions of long-straight-chain hydrazides with carbon disulfide in alkaline media give the corresponding carbodithioate salts. Heating of potassium 2-alkanoylhydrazinecarbodithioates with phenacyl bromide do not yield cyclization and failed to give the corresponding long-chain thiazolidine-2-thiones, but gave the corresponding 2-oxo-2-phenylethyl-2-alkanoylhydrazinecarbodithioates via nucleophilic substitution reaction. In addition, the synthesized compounds were tested for their corrosion prevention capabilities in acidic or in mineral oil media. Correspondence: Ayhan Yıldırım, Department of Chemistry, Faculty of Science and Arts, Uludağ University, 16059 Bursa, Turkey.     

A branch-cut-and-price algorithm for optimal decoding in digital communication systems

Journal of Global Optimization - Channel coding aims to minimize the errors that occur during the transmission of digital information from one place to another. Low-density parity-check codes can...     

A generalization of the Fourier transform and its application to spectral analysis of chirp-like signals

We show that the de Branges theory provides a useful generalization of the Fourier transform (FT). The formulation is quite rich in that by selecting the appropriate parametrization, one can obtain spectral representation for a number of important cases. We demonstrate two such cases in this paper: the finite sum of elementary chirp-like signals, and a decaying chirp using Bessel functions. We show that when defined in the framework of de Branges spaces, these cases admit a representation very much similar to the spectral representation of a finite sum of sinusoids for the usual FT.     

Pooling in tandem queueing networks with non-collaborative servers

This paper considers pooling several adjacent stations in a tandem network of single-server stations with finite buffers. When stations are pooled, we assume that the tasks at those stations are pooled but the servers are not. More specifically, each server at the pooled station picks a job from the incoming buffer of the pooled station and conducts all tasks required for that job at the pooled station before that job is placed in the outgoing buffer. For such a system, we provide sufficient conditions on the buffer capacities and service times under which pooling increases the system throughput by means of sample-path comparisons. Our numerical results suggest that pooling in a tandem line generally improves the system throughput—substantially in many cases. Finally, our analytical and numerical results suggest that pooling servers in addition to tasks results in even larger throughput when service rates are additive and the two systems have the same total number of storage spaces.