693 research outputs found

    An artificial intelligence approach to job-shop scheduling

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    Thesis (M.S.)--Massachusetts Institute of Technology, Sloan School of Management, 1984.MICROFICHE COPY AVAILABLE IN ARCHIVES AND DEWEY.Bibliography: leaf 52.by George L. Clemmer, II.M.S

    Resolution and structural transitions of elongated states of ubiquitin

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    Electrospray ionization, combined with two-dimensional ion mobility spectrometry and mass spectrometry, is used to produce, select, and activate distributions of elongated ions, [M Ļ© 11H] 11Ļ© to [M Ļ© 13H] 13Ļ© , of ubiquitin. The analysis makes it possible to examine state-to-state transitions for structural types, and transition diagrams associated with the efficiencies of structural changes are presented. The Ļ©11 and Ļ©12 charge states can form four resolvable states while only one state is formed for [M Ļ© 13H] 13Ļ© . Some conformations, which appear to belong to the same family based on mobility analysis of different charge states, undergo similar transitions, others do not. Activation of ions that exist in low-abundance conformations, having mobilities that fall in between sharp peaks associated with higher abundances species, shows that the low-abundance forms undergo efficient (Ļ³90 to 100%) conversion into states associated with well-defined peaks. This efficiency is significantly higher than the Ļ³10 to 60% efficiency of transitions of structures associated with well-defined peaks. The formation of sharp features from a range of low-intensity species with different cross sections indicates that large regions of conformation space must be unfavorable or inaccessible in the gas phase. These results are compared with several previous IMS measurements of this system as well as information about gas-phase structure provided by other techniques. Studies of solvent-free proteins and peptides are important because of both fundamental and practical considerations. In the absence of solvation shells (or with minimal solvent), it is possible to extract kinetic and thermodynamic benchmarks about the formation of specific types of folds and tease out the influence of solvent-molecule and intramolecular factors in establishing conformation [2] A number of groups have worked to combine ion mobility spectrometry (IMS) and MS with the aim of using differences in ion mobility to separate components of a mixture that would not be resolved by MS alone [21, 22]. The mobility of a macromolecular ion through a buffer gas depends on its charge and shape (average collision cross section with the buffer gas, ā€). Recently, we have ex- tended a hybrid IMS/MS instrument to include additional IMS dimensions leading to IMS-IMS/MS and IMS-IMS-IMS/MS instrument designs As one develops new IMS techniques (as well as other methods) it is important to revisit model systems, where some fundamental understanding of the nature of the system exists. In the present paper, we focus on the Ļ©11 to Ļ©13 charge states of ubiquitin ions produced by standard ESI conditions. Ubiquitin is a small, 76 amino acid protein that, under most ESI source conditions, favors the Ļ©5 to Ļ©13 charge states [27

    Achieving favourable customer outcomes through employee deviance

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    This study advances current knowledge by examining how employee deviance and customer participation during a single employee-customer exchange generate favourable customer responses. This work bridges the employee deviance stream with the service encounter literature and illustrates the importance of equity theory in deviant service exchanges between customers and employees. Moreover, results add to the ongoing debate on service nepotism by canvassing the consequences from the customerā€™s active participation in deviant exchanges which appears to enhance customer perceptions of the exchange. A 3x2 between-subjects experimental design was adopted which manipulates three types of pro-customer deviance along with customerā€™s participation (or not) to the exchange. The dependent variables capture three types of perceived customer justice (cognitive outcomes) and customerā€™s affective state (affective outcome). Findings illustrate that customers approve employeesā€™ deviance for their own benefit while also indicate favourable outcomes from deviant exchanges with employees such as higher perceived justice and a more positive affective state. The article concludes with a discussion of the theoretical and managerial implications, limitations and research directions that emerge from this study

    High resolution genomic analysis of sporadic breast cancer using array-based comparative genomic hybridization

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    INTRODUCTION: Genomic aberrations in the form of subchromosomal DNA copy number changes are a hallmark of epithelial cancers, including breast cancer. The goal of the present study was to analyze such aberrations in breast cancer at high resolution. METHODS: We employed high-resolution array comparative genomic hybridization with 4,134 bacterial artificial chromosomes that cover the genome at 0.9 megabase resolution to analyze 47 primary breast tumors and 18 breast cancer cell lines. RESULTS: Common amplicons included 8q24.3 (amplified in 79% of tumors, with 5/47 exhibiting high level amplification), 1q32.1 and 16p13.3 (amplified in 66% and 57% of tumors, respectively). Moreover, we found several positive correlations between specific amplicons from different chromosomes, suggesting the existence of cooperating genetic loci. Queried by gene, the most frequently amplified kinase was PTK2 (79% of tumors), whereas the most frequently lost kinase was PTK2B (hemizygous loss in 34% of tumors). Amplification of ERBB2 as measured by comparative genomic hybridization (CGH) correlated closely with ERBB2 DNA and RNA levels measured by quantitative PCR as well as with ERBB2 protein levels. The overall frequency of recurrent losses was lower, with no region lost in more than 50% of tumors; the most frequently lost tumor suppressor gene was RB1 (hemizygous loss in 26% of tumors). Finally, we find that specific copy number changes in cell lines closely mimicked those in primary tumors, with an overall Pearson correlation coefficient of 0.843 for gains and 0.734 for losses. CONCLUSION: High resolution CGH analysis of breast cancer reveals several regions where DNA copy number is commonly gained or lost, that non-random correlations between specific amplicons exist, and that specific genetic alterations are maintained in breast cancer cell lines despite repeat passage in tissue culture. These observations suggest that genes within these regions are critical to the malignant phenotype and may thus serve as future therapeutic targets

    Characterization of adjacent breast tumors using oligonucleotide microarrays

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    BACKGROUND: Current methodology often cannot distinguish second primary breast cancers from multifocal disease, a potentially important distinction for clinical management. In the present study we evaluated the use of oligonucleotide-based microarray analysis in determining the clonality of tumors by comparing gene expression profiles. METHOD: Total RNA was extracted from two tumors with no apparent physical connection that were located in the right breast of an 87-year-old woman diagnosed with invasive ductal carcinoma (IDC). The RNA was hybridized to the Affymetrix Human Genome U95A Gene Chip(Ā®) (12,500 known human genes) and analyzed using the Gene Chip Analysis Suite(Ā®) 3.3 (Affymetrix, Inc, Santa Clara, CA, USA) and JMPIN(Ā®) 3.2.6 (SAS Institute, Inc, Cary, NC, USA). Gene expression profiles of tumors from five additional patients were compared in order to evaluate the heterogeneity in gene expression between tumors with similar clinical characteristics. RESULTS: The adjacent breast tumors had a pairwise correlation coefficient of 0.987, and were essentially indistinguishable by microarray analysis. Analysis of gene expression profiles from different individuals, however, generated a pairwise correlation coefficient of 0.710. CONCLUSION: Transcriptional profiling may be a useful diagnostic tool for determining tumor clonality and heterogeneity, and may ultimately impact on therapeutic decision making

    Narratives of self and identity in women's prisons: stigma and the struggle for self-definition in penal regimes

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    A concern with questions of selfhood and identity has been central to penal practices in women's prisons, and to the sociology of women's imprisonment. Studies of women's prisons have remained preoccupied with women prisonersā€™ social identities, and their apparent tendency to adapt to imprisonment through relationships. This article explores the narratives of women in two English prisons to demonstrate the importance of the self as a site of meaning for prisoners and the central place of identity in micro-level power negotiations in prisons

    Adsorption Isotherms of Hydrogen: The Role of Thermal Fluctuations

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    It is shown that experimentally obtained isotherms of adsorption on solid substrates may be completely reconciled with Lifshitz theory when thermal fluctuations are taken into account. This is achieved within the framework of a solid-on-solid model which is solved numerically. Analysis of the fluctuation contributions observed for hydrogen adsorption onto gold substrates allows to determine the surface tension of the free hydrogen film as a function of film thickness. It is found to decrease sharply for film thicknesses below seven atomic layers.Comment: RevTeX manuscript (3 pages output), 3 figure
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