Residual finiteness of a class of semigroups presented by a single relation

Communicated by Dominique Perrin     

Heats of mixing of 2,2-dimethoxypropane and diethoxymethane with some 1-alkenes

The excess enthalpies of 2,2-dimethoxypropane + 1-hexene, + 1-heptene and + 1-octene, and of diethoxymethane + 1-hexene + 1-octene have been measured at 298.15 K. The values of H^E for all the systems are positive and increase with increasing chain length of the alkene. The results are analysed in term of the quasi-lattice theory of mixtures using the zeroth approximation.     

Microdetermination of monosaccharides in glycoproteins: I. Electrophoretic methods

A sensitive method that has been developed for determination of monosaccharides in glycoproteins is based on high-voltage electrophoretic separation of tritium-labeled monosaccharides. Precise quantitation is mediated by using internal standards, specific for each monosaccharide in the sample. The application of this method and its reproducibility has been demonstrated by analysis of the carbohydrate moiety of immunoglobulins.     

A canonical structure for iterative procedures

In this paper a canonical structure for multistep finite memory algorithms is presented. The concept of characteristic set is introduced and some of the finite and limit properties of the structure are proved. Then it is shown that the use of the theory developed in the paper's first part greatly simplifies the analysis of complicated iterative procedures.     

Generation and amplification of sub-picosecond pulses using a frequency-doubled neodymium YAG pumping source

Stable, tunable, sub-picosecond pulses have been obtained by synchronously pumping a Rhodamine 6G dye laser with a frequency-doubled CW modelocked neodymium YAG laser. Careful attention has been paid to minimize amplitude and timing instabilities, resulting in dye laser pulses shorter than 500 fs. The main advantage of this new pumping source over current synchronously pumped dye lasers is that it is particularly well suited to short pulse amplification. Using this technique amplification of 2 × 10⁶ has been achieved.     

The pentad rotation-vibrational states of 12CD4: Wavenumber analysis of infrared and Raman spectra of the ν1, ν3, 2ν2, ν2 + ν4, and 2ν4 bands

The so-called pentad of ¹²CD₄ consists of the vibrational states v₁ = 1(symmetry A₁), v₃ = 1(F₂), v₂ = 2(A₁ + E), v₂ = v₄ = 1(F₁ + F₂), and v₄ = 2(A₁ + E + F₂). All states are located in the 1950 to 2250-cm^?1 region and all are strongly interacting. In the present work we have assigned more than 5000 infrared rotation-vibrational transitions and 163 isotropic Raman transitions from the vibrational ground state to the pentad. We have used infrared and Raman spectra of a resolution better than 0.01 cm^?1. From the experimental wavenumbers 2567 pentad rotation-vibrational energy levels with J ≦ 20 have been determined. These levels are reported in the paper. The levels have been used for refinements of the spectroscopic constants of two physically different effective Hamiltonians for the pentad states. For all levels with J ≦ 12 an unweighted standard deviation of 0.004 cm^?1 is obtained for both Hamiltonians, whereas the standard deviation increases more or less rapidly with J above 12 due to the imperfections of the Hamiltonians. The values of the spectroscopic constants of both Hamiltonians (85 and 106, respectively) are reported and the effects of the approximations are discussed.     

Extensions of set partitions

A τ-partition of a subset of a given p-set X can be extended in many different ways to a τ-partition of X. The Stirling number of the second kind S(p, τ) can be defined as the number of all τ-partitions of X, and can be regarded as the number of all possible extensions of the τ-partitions of all the τ-subsets of X. In this paper we study the number of extensions for a particular choice of τ-partitions of the m-subsets of X, with 1 ? m ? p.     

Simplicity of crossed products by endomorphisms

Conditions are given for simplicity of the crossed product of a unital C^*-algebra by an endomorphism.     

Double-resonance circuit for nuclear magnetic resonance spectroscopy

A new double-resonance probe circuit design is described. The circuit contains no quarter-wavelength elements or equivalents, yet nonetheless achieves adequate isolation between the two input channels. It contains relatively few components, and so is both compact and efficient. It has been incorporated in two solid-state nuclear magnetic resonance (NMR) probes, with excellent results.