A simple formula for mean multiplexing delay for independent regenerative sources

Simple expressions are given for the mean delay, mean waiting time, and mean busy period length in a multiplexer. Data streams with active periods having a general distribution are permitted, and the data rate during the active periods can be random. Data can also arrive in batches. The key restrictions of the model are that the sources are independent, idle periods are exponentially distributed, and a source generates at least enough data during an active period to keep the server busy throughout the period. The exact formulas allow evaluation of the error in approximations such as a heavy traffic diffusion approximation.Both continuous and discrete time models are considered. The discrete-time model includes that studied by Viterbi and subsequently generalized by Neuts. The Pollaczek-Khinchine formula for the mean amount of work in anM/GI/1 queue is retrieved as a limiting case.Preliminary version presented at IEEE INFOCOM, San Francisco, April 1993.     

Quantitation and characterization of phospholipids in pharmaceutical formulations by liquid chromatography-mass spectrometry

A simple and fast method for phospholipid analysis was developed using high-performance liquid chromatography-mass spectrometry with an atmospheric pressure ionization interface. Separation of the phospholipid molecular species was achieved using a linear gradient of a mixture of chloroform-10 mM ammonium acetate-methanol (30:5:65) on a silica column. Optimization of the mass spectrometer conditions has allowed the method to separate and detect the phospholipids mainly as protonated molecular species. In comparison to existing LC-MS methods, improvement in the total analysis time and sensitivity were achieved. Separation of all major phospholipid molecular classes was achieved in less than 6 min. Marked improvement was observed in the linearity of the response of the phospholipids studied providing a linear response over three orders of magnitude. Data supporting the validation of this method for the characterization of major phospholipids molecular species are also presented.     

Etude des métastannates de cadmium par spectrographie d'absorption infrarouge entre 5 et 40μ. Solutions solides entre l'oxyde d'étain et Poxyde de cadmium

Résumé Par chauffage à 1000° de mélanges d'oxyde stannique et d'oxyde de cadmium en proportions diverses, comme par déshydratation de précipités mixtes des hydroxydes correspondants, il se forme une série de solutions solides de l'oxyde de cadmium dans l'oxyde d'étain. Elles sont solubles dans l'acide chlorhydrique et présentent un spectre d'absorption infrarouge caractéristique que l'on a comparé avec celui des 2 métastannates de cadmium CdSnO₃, l'un de type ilménite, l'autre de type perovskite.

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Summary By heating various mixture of stannic oxide and cadmium oxide to 1000° C, a series of solid solutions of cadmium oxide in stannic oxide results as is the case when mixed precipitates of the corresponding hydroxides are dehydrated. They are soluble in hydrochloric acid and yield a characteristic infrared absorption spectrum that was compared with that of the two cadmium métastannates CdSnO₃, one of the ilmenite type, the other of the perovskite type.

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Zusammenfassung Erhitzt man verschieden zusammengesetzte Gemische von Zinnoxid und Cadmiumoxid auf 1000° C oder werden Mischfällungen der entsprechenden Hydroxide dehydratisiert, so entsteht eine Reihe fester Lösungen von Cadmiumoxid in Zinnoxid. Sie sind in Salzsäure löslich und zeigen ein charakteristisches Absorptionsspektrum im IR. Dieses wurde mit dem Spektrum zweier Cadmium-Metastannate (CdSnO₃) vom Typus des Ilmenits bzw. Perovskits verglichen.

     

Static dipole polarizability of electronically excited molecules: H2(B1Σu+)

The dipole polarizability of H₂(B¹Σ_u⁺) is computed using extended Gaussian basis sets and Hartree-Fock, multiconfiguration Hartree-Fock, and configuration interaction wavefunctions. Electron correlation contributions are found to be significant (≈ 25%) with the largest contribution arising from angular correlation. With a full CI wavefunction, the components of the dipole polarizability were computed to be (in au): α_⊥ = 50 and α_| = 257.     

Etude de la structure de l'iodatochromate de potassium par spectrographie d'absorption infrarouge entre 3 et 35μ

Résumé Dans le spectre d'absorption infrarouge de l'iodatochromate de potassium K[(CrO₃)(IO₃)], on peut identifier la présence de bandes de vibration de valence de ponts Cr-0-I à 508 et680 cm^–1.

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Summary The infrared absorption spectrum of potassium iodatochromate K(CrO₃)(IO₃) contains vibration bands of the valence bridges Cr-O-I at 508 and 680 cm^–1.

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Zusammenfassung Im Infrarot-Absorptionsspektrum des Kaliumjodatochromats lassen sich Banden der Valenzschwingungen der Atomgruppe Or-O-J bei 508 und 680 cm^–1 nachweisen.

     

The electronic spectrum of the triethylamine-perfluoro-tert-butanol complex

The far-ultraviolet absorption spectrum of the triethylamine-perfluoro-tert-butanol complex has been measured in the gas phase. The photoelectron band of lowest energy has also been determined. It is about 13000 cm^?1 higher than for free triethylamine. Up to at least 60000 cm^?1, the UV spectrum is readily interpreted as a triethylamine spectrum shifted to higher frequencies by about 13000 cm^?1. The bands of lowest frequency are the 3s and 3p Rydberg bands which follow the ionization potential. Up to 60000 cm^?1, no charge transfer type band has been found.     

Computation of electron repulsion integrals using the rys quadrature method

Following an earlier proposal to evaluate electron repulsion integrals over Gaussian basis functions by a numerical quadrature based on a set of orthogonal polynomials (Rys polynomials), a computational procedure is outlined for efficient evaluation of the two-dimensional integrals I_x, I_y, and I_z. Compact recurrence formulas for the integrals make the method particularly fitted to handle high-angular-momentum basis functions. The technique has been implemented in the HONDO molecular orbital program.