1,721,008 research outputs found
Comparison of detergent-based sample preparation workflows for LTQ-Orbitrap analysis of the Escherichia coli proteome
No full textThis work presents a comparative evaluation of several detergent-based sample preparation workflows for the MS-based analysis of bacterial proteomes, performed using the model organism Escherichia coli. Initially, RapiGest- and SDS-based buffers were compared for their protein extraction efficiency and quality of the MS data generated. As a result, SDS performed best in terms of total protein yields and overall number of MS identifications, mainly due to a higher efficiency in extracting high molecular weight (MW) and membrane proteins, while RapiGest led to an enrichment in periplasmic and fimbrial proteins. Then, SDS extracts underwent five different MS sample preparation workflows, including: detergent removal by spin columns followed by in-solution digestion (SC), protein precipitation followed by in-solution digestion in ammonium bicarbonate or urea buffer, filter-aided sample preparation (FASP), and 1DE separation followed by in-gel digestion. On the whole, about 1000 proteins were identified upon LC-MS/MS analysis of all preparations (>1100 with the SC workflow), with FASP producing more identified peptides and a higher mean sequence coverage. Each protocol exhibited specific behaviors in terms of MW, hydrophobicity, and subcellular localization distribution of the identified proteins; a comparative assessment of the different outputs is presented
3D minimum reaction control for space manipulators
No full textThis paper presents a novel controller for a generic 3D multibody space system. The control is designed to minimize the dynamic coupling between one of the bodies and the rest of the system, e.g. a spacecraft endowed with a robotic manipulator. Standard control techniques suffer of some limitations. For instance, the Jacobian Transposed (JT) control does not explicitly address the reduction of the reaction forces over the main body. Or else, the so-called “Reaction Null” (RN) technique has a limited workspace due to the strictness of the constraint of zero reactions over the spacecraft. A new closed-loop controller, called Minimum Reaction (MR) control, is designed by combining the RN and JT approaches, so that the dynamic coupling between base platform and manipulator is reduced, while achieving the desired end effector position with great precision. In fact, the reactions on the base are minimized but not constrained to be null as in RN, so that the workspace of the manipulator is extended at its maximum. To this end, the non-linear 3D dynamics of a multibody system is derived in matrix form. Then, a minimum reaction control problem is formulated and solved analytically using a quadratic cost function. The presented solution is applied to a typical mission scenario involving a robotic arm deployment, both in the case of a rigid multibody system and in the case in which a flexible appendage (such as a solar panel) is included. Results are compared with a Jacobian Transposed controller and a Reaction Null controller and discussed
2-D PAGE and MS analysis of proteins from formalin-fixed, paraffin-embedded tissues
No full textIn the past decade, encouraging results have been obtained in extraction and analysis of proteins from formalin-fixed, paraffin-embedded (FFPE) tissues. However, 2-D PAGE protein maps with satisfactory proteomic information and comparability to fresh tissues have never been described to date. In the present study, we report 2-D PAGE separation and MS identification of full-length proteins extracted from FFPE skeletal muscle tissue. The 2-D protein profiles obtained from FFPE tissues could be matched to those achieved from frozen tissues replicates. Up to 250 spots were clearly detected in 2-D maps of proteins from FFPE tissue following standard mass-compatible silver staining. Protein spots from both FFPE and frozen tissue 2-D gels were excised, subjected to in situ hydrolysis, and identified by MS analysis. Matched spots produced matched protein identifications. Moreover, 2-D protein maps from FFPE tissues were successfully subjected to Western immunoblotting, producing comparable results to fresh-frozen tissues. In conclusion, this study provides evidence that, when adequately extracted, full-length proteins from FFPE tissues might be suitable to 2-D PAGE-MS analysis, allowing differential proteomic studies on the vast existing archives of healthy and pathological-fixed tissues
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Impact of fixation time on GeLC-MS/MS proteomic profiling of formalin-fixed, paraffin-embedded tissues
No full textFormalin-fixed, paraffin-embedded (FFPE) tissue banks represent an invaluable resource for biomarker discovery. Recently, the combination of full-length protein extraction, GeLC-MS/MS analysis, and spectral counting quantification has been successfully applied to mine proteomic information from these tissues. However, several sources of variability affect these samples; among these, the duration of the fixation process is one of the most important and most easily controllable ones. To assess its influence on quality of GeLC-MS/MS data, the impact of fixation time on efficiency of full-length protein extraction efficiency and on quality of label-free quantitative data was evaluated.As a result, although proteins were successfully extracted from FFPE liver samples fixed for up to eight days, fixation time appeared to negatively influence both protein extraction yield and GeLC-MS/MS quantitative proteomic data. Particularly, MS identification efficiency decreased with increasing fixation times. Moreover, amino acid modifications putatively induced by formaldehyde were detected and characterized.These results demonstrate that proteomic information can be achieved also from tissue samples fixed for relatively long times, but suggest that variations in fixation time need to be carefully taken into account when performing proteomic biomarker discovery studies on fixed tissue archives
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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