Multipion and strange particle photoproduction off neutrons up to 5.3 GeV

In a study of photoproduction at photon energies up to 5.3 GeV in a deuterium bubble chamber the reactions γn→pπ⁺π^?π^? and γn→pπ⁺π^?π^?π⁰ were analyzed. In these reactions production of the resonances Δ⁺⁺, Δ⁰, ?⁰, ω and A₂^? was observed. Photoproduction of strange particles was investigated and cross sections for the reactions γn→ΛK⁺π^?, Σ^?K⁰π⁺, pK^?K⁰, ΛK⁰π⁺π^? and ΛK⁺π^?π⁰ are presented. Production of Σ^?(1385) and K¹⁰(890) was observed.     

Web agents that work

Intelligent search applications are the future direction for the World Wide Web and for the Internet in general, but without the ability to gather and understand exact information about multimedia data and documents, making these applications a reality will be difficult. In the future, we may have the technology necessary to read human-oriented multimedia documents. Making the Web less agent-hostile takes great strides toward that goal today     

Zero‐field μ+SR study of the colossal magnetoresistance material La0.67Ca0.33MnO3

Zero‐field μ⁺SR and resistivity experiments on La_0.67Ca_0.33MnO₃ powder show that the ferromagnetic transition temperature (T_C=274\ K) and resistivity peak temperature coincide to within 1 K, about 10 K higher than T_C determined from the bulk magnetization. The sublattice magnetization \nu_μ(T) is well described for T ≤ T_C by (1-T/T_C)^β , where β =0.345 ± 0.015. Unusual relaxation dynamics suggest a wide distribution of Mn‐ion correlation times. These results are discussed in terms of the effects of polarons on the spin and charge dynamics. This revised version was published online in July 2006 with corrections to the Cover Date.     

Connecting Lisp-Stat to COM

Abstract

This article describes an interface between Lisp-Stat and Microsoft's Component Object Model (COM). This interface can be used, for example, to retrieve data stored in a spreadsheet or a database. After providing some brief background on Lisp-Stat and COM, the interface is presented through a series of examples. Issues in implementation and integration relevant to other statistical systems and other component systems are discussed.     

Using accurate mass electrospray ionization-time-of-flight mass spectrometry with in-source collision-induced dissociation to sequence peptide mixtures

Although data-dependent LC-MS-MS with database searching has become au courant for identifying proteins, the technique is constrained by duty-cycle inefficiency and the inability of most tandem mass analyzers to accurately measure peptide product ion masses. In this work, a novel approach is presented for simultaneous peptide fragmentation and accurate mass measurement using in-source collision-induced dissociation (CID) on electrospray ionization (ESI)-time-of-flight (TOF) MS. By employing internal mass reference compounds, mass measurement accuracy within +/-5 ppm for tryptic peptide precursors and +/-10 ppm for most sequence-specific product ions was consistently achieved. Analysis of a complex solution containing several digested protein standards did not adversely affect instrument performance.     

Analysis of vitamin E derivatives in serum using coordinated ion spray mass spectrometry

A method for the extraction and analysis of tocopherols from serum using coordinated ion spray (CIS) mass spectrometry was developed and tested. The tocopherols were extracted from serum and analyzed by direct infusion into the mass spectrometer, bypassing the need for a liquid chromatography step. CIS is a method for improving the ionization efficiency of non-polar compounds by adding metal ions to the electrospray solvent. The non-polar analytes appear as metal adducts in the resulting mass spectrum. Silver was used as the metal ion for the CIS, causing analyte masses to be increased by 107 and 109 Da from the two main silver isotopes. Vitamin E succinate was added to the samples before extraction and was used as an internal standard to compensate for any variations in the extraction efficiency or mass spectrometric response. alpha-Tocopherol and an ether-linked analogue known as alpha-TEA were analyzed in concentrations from 1.25-40 microg/mL (1.9-60 pg consumed). The response curve was constructed by comparing the response of the analytes to the internal standard and gave linear results with r2 values greater than 0.98. This new method was shown to be sensitive, reproducible, fast and required very small amounts of analyte.     

Nature of interaction energy anisotropy in the Li(<Superscript>2</Superscript>S)–HF (˜X<Superscript>1</Superscript>Σ<Superscript>+</Superscript>) van der Waals complex. A theoretical study

The potential-energy surface for the Li(²S)–HF (? X¹Σ⁺ interaction, where HF is kept rigid, is calculated using the supermolecular unrestricted fourth-order Møller–Plesset perturbation theory. The basis set superposition error corrected potential indicates two minima. The global minimum occurs for the bent Li...FH structure at R=1.95 Å and θ=70° with a relatively deep well of D_e=1,706 cm^?1 and the secondary minimum is found for the linear Li...HF configuration at R=4.11 Å with a well depth ofD_e=288 cm^?1. A barrier of 177 cm^?1 (with respect to the secondary linear minimum) separates these two minima. In this study 27 bound states of the bent Li...FH minimum and eight bound states of the linear Li...HF minimum up to the Li+HF dissociation threshold are calculated. The energy partitioning using the intermolecular perturbation theory scheme shows that the origins of the stability of the structures studied are entirely different. The global minimum is stabilised using the attractive Coulombic interaction and unrestricted Hartree–Fock deformation energy. The latter term originates from the mutual electric polarisation effects. The secondary linear minimum is mostly determined by the anisotropy of the repulsive Heitler–London exchange-penetration and attractive dispersion energies.     

Identification, isolation, and characterization of cysteinate and thiolactate complexes of bismuth

Although bismuth compounds have been used in medicine for over 200 years, chemical characterization of complexes involving biological molecules is minimal and mechanisms of bioactivity are ill-defined. The thiophilic nature of bismuth implicates sulfur centers as likely sites for interaction, and we have exploited this feature to identify, isolate, and characterize complexes of bismuth with thiolate-carboxylate bifunctional ligands including the amino acid l-cysteine. The solid-state structures of potassium dichloro(thiopropionato)bismuth (K[1d]), dimethylaminoethanethiolato(thiopropionato)bismuth (4), and dinitrato(cysteinato)bismuthphenanthroline [5(phen)] are compared with data from electrospray ionization mass spectrometry (ESI-MS). ESI-MS is applied to reactions of BiCl(3) or Bi(NO(3))(3) with mercaptosuccinic, malic, and succinic acids to illustrate the general observation of 1:1 and 1:2 complexes.