Computer control of mass analyzers

Digital computer control of mass spectrometer

A computer operated mass spectrometer system

Digital computer system for processing mass spectrometer output dat

C*-Structure and K-Theory of Boutet de Monvel's Algebra

We consider the norm closure $A$ of the algebra of all operators of order and class zero in Boutet de Monvel's calculus on a manifold $X$ with boundary $Y$. We first describe the image and the kernel of the continuous extension of the boundary principal symbol to $A$. If the $X$ is connected and $Y$ is not empty, we then show that the K-groups of $A$ are topologically determined. In case the manifold, its boundary and the tangent space of the interior have torsion-free K-theory, we prove that $K_i(A/K)$ is isomorphic to the direct sum of $K_i(C(X))$ and $K_{1-i}(C_0(TX'))$, for i=0,1, with $K$ denoting the compact ideal and $TX'$ the tangent bundle of the interior of $X$. Using Boutet de Monvel's index theorem, we also prove this result for i=1 without assuming the torsion-free hypothesis. We also give a composition sequence for $A$.Comment: Final version, to appear in J. Reine Angew. Math. Improved K-theoretic result

Environmental metabolomics : databases and tools for data analysis

© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Marine Chemistry 177 (2015): 366–373, doi:10.1016/j.marchem.2015.06.012.Metabolomics is the study of small molecules, or ‘metabolites’, that are the end products of biological processes. While -omics technologies such as genomics, transcriptomics, and proteomics measure the metabolic potential of organisms, metabolomics provides detailed information on the organic compounds produced during metabolism and found within cells and in the environment. Improvements in analytical techniques have expanded our understanding of metabolomics and developments in computational tools have made metabolomics data accessible to a broad segment of the scientific community. Yet, metabolomics methods have only been applied to a limited number of projects in the marine environment. Here, we review analysis techniques for mass spectrometry data and summarize the current state of metabolomics databases. We then describe a boutique database developed in our laboratory for efficient data analysis and selection of mass spectral targets for metabolite identification. The code to implement the database is freely available on GitHub (https://github.com/joefutrelle/domdb). Data organization and analysis are critical, but often under-appreciated, components of metabolomics research. Future advances in environmental metabolomics will take advantage of continued development of new tools that facilitate analysis of large metabolomics datasets.The field data populating the database comes from scientific cruises funded by grants from the National Science Foundation to EBK and KL (Atlantic Ocean, OCE-1154320) and E.V. Armbrust (Pacific Ocean, OCE-1205233). The laboratory experiment with coastal seawater was funded by a grant from the Gulf of Mexico Research Initiative to EBK and H.K. White. The laboratory experiments with microbial isolates and the database development are funded by the Gordon and Betty Moore Foundation through Grant GBMF3304 to EBK

Development of the combined method of hardening of the surface of aluminium

Представлены результаты, полученные при исследовании фазового и элементного состава, дефектной субструктуры поверхности технически чистого алюминия марки А7, подвергнутого комбинированной обработке, сочетающей напыление металлической пленки, электронно-пучковое перемешивание системы пленка/подложка и последующее азотирование в плазме газового разряда низкого давления. Выполнен анализ закономерностей, выявлены режимы воздействия, позволяющие кратно повышать микротвердость и износостойкость материала.The results are presented, received at research of phase and elemental composition, defective substructureof surface technically pure aluminium of the A7, subjected to the combined processing combining spraying metalfilm, electron-beam mixing of system film/substrate and subsequent nitriding in plasma of the gas discharge of lowpressure. The analysis of regularities is made, revealed the modes of influence allowing multiple to raise amicrohardness and wear resistance of material

Ten per cent polarized optical emission from GRB 090102

The nature of the jets and the role of magnetic fields in gamma-ray bursts (GRB) remains unclear. In a baryon-dominated jet only weak, tangled fields generated in situ through shocks would be present. In an alternative model, jets are threaded with large scale magnetic fields that originate at the central engine and which accelerate and collimate the jets. The way to distinguish between the models is to measure the degree of polarization in early-time emission, however previous claims of gamma-ray polarization have been controversial. Here we report that the early optical emission from GRB 090102 was polarized at the level of P=10+/-1%, indicating the presence of large-scale fields originating in the expanding fireball. If the degree of polarization and its position angle were variable on timescales shorter than our 60-s exposure, then the peak polarization may have been larger than 10 per cent.Comment: 16 pages, 4 figures. Published in Nature (2009), Vol. 462, p767-76

Mixing Quantum and Classical Mechanics

Using a group theoretical approach we derive an equation of motion for a mixed quantum-classical system. The quantum-classical bracket entering the equation preserves the Lie algebra structure of quantum and classical mechanics: The bracket is antisymmetric and satisfies the Jacobi identity, and, therefore, leads to a natural description of interaction between quantum and classical degrees of freedom. We apply the formalism to coupled quantum and classical oscillators and show how various approximations, such as the mean-field and the multiconfiguration mean-field approaches, can be obtained from the quantum-classical equation of motion.Comment: 31 pages, LaTeX2

Diffuse Galactic Soft Gamma-Ray Emission

The Galactic diffuse soft gamma-ray (30-800 keV) emission has been measured from the Galactic Center by the HIREGS balloon-borne germanium spectrometer to determine the spectral characteristics and origin of the emission. The resulting Galactic diffuse continuum is found to agree well with a single power-law (plus positronium) over the entire energy range, consistent with RXTE and COMPTEL/CGRO observations at lower and higher energies, respectively. We find no evidence of spectral steepening below 200 keV, as has been reported in previous observations. The spatial distribution along the Galactic ridge is found to be nearly flat, with upper limits set on the longitudinal gradient, and with no evidence of an edge in the observed region. The soft gamma-ray diffuse spectrum is well modeled by inverse Compton scattering of interstellar radiation off of cosmic-ray electrons, minimizing the need to invoke inefficient nonthermal bremsstrahlung emission. The resulting power requirement is well within that provided by Galactic supernovae. We speculate that the measured spectrum provides the first direct constraints on the cosmic-ray electron spectrum below 300 MeV.Comment: 26 pages, 7 figure, submitted to Ap

The 1999 Hercules X-1 Anomalous Low State

A failed main-on in the 35d cycle of Her X-1 was observed with the Rossi X-Ray Timing Explorer (RXTE) on 1999 April 26. Exceptions to the normal 35d cycle have been seen only twice before; in 1983 and again 1993. We present timing and spectral results of this latest Anomalous Low State (ALS) along with comparisons to the main-on and normal low states. Pulsations were observed in the 3-18 keV band with a fractional RMS variation of (0.037+-0.003). Spectral analysis indicates that the ALS spectrum has the same shape as the main-on but is modified by heavy absorption and scattering. We find that 70% of the observed emission has passed through a cold absorber (N_H=5.0x10^{23}cm^{-2}). This partially absorbing spectral fit can be applied to the normal low state with similar results. We find that the ALS observations may be interpreted as a decrease in inclination of the accretion disk causing the central X-Ray source to be obscured over the entire 35d cycle.Comment: revised text, 6 revised figures, accepted for publication in Ap