1,721,028 research outputs found
Commissioning of the tracking system in the ATLAS detector
Full text linkATLAS is one of the four experiments that will analyze the p-p collisions at LHC. It consists of several subsystems: the Inner Detector is devoted to the measurement of the charged particle tracks in the interaction point region and the Pixel Detector is its innermost component. Both have been commissioned by using cosmic rays collected by the ATLAS detector in 2009. In the first part of the thesis, the spatial resolution of the Pixel Detector is studied and optimized. When a charged particle traverses the Pixel Detector, charges released in the sensors are collected by segmented electrodes, the pixels. The charge of each pixel is read out by the Time-over-Threshold technique and adjacent pixels are grouped into clusters. Cluster position can be computed by considering its geometrical center, but spatial resolution can be optimized if using charge information to improve position determination. In the second part of the thesis, the Inner Detector resolution in all track parameters has been studied by splitting each cosmic ray track into two halves. Since both halves stem from the same particle, they should be described by the same parameters. At the same time, the two tracks are fitted independently and can be compared to study the resolution of the tracking system. Resolution been studied as a function of track direction and distance from the beam axis. The multiple scattering contribution and several systematic effects due to residual misalignments have been evaluated
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
Influence of composition on rheological properties and processability of mLLDPE/LDPE blends
No full textPerspectives for the detection and measurement of supersymmetry in the focus point region of mSUGRA models with the ATLAS detector at LHC
Full text linkThis paper discusses the ATLAS potential to study Supersymmetry for the "Focus-Point" region of the parameter space of mSUGRA models. The potential to discovery a deviation from Standard Model expectations with the first few of LHC data was studied using the parametrized simulation of the ATLAS detector. Several signatures were considered, involving hard jets, large missing energy, and either -tagged jets, opposite-sign isolated electron or muon pairs, or top quarks reconstructed exploiting their fully hadronic decays. With only 1 of data each of these signatures may allow to observe an excess of events over Standard Model expectation with a statistical significance exceeding 5 standard deviations. An analytical expression was derived for the shape of the distribution of the dilepton invariant mass arising from the three-body leptonic decay of the neutralinos under the hypothesis of heavy scalars, which is appropriate for the focus-point scenario. The resulting function was used to fit the distribution of the dilepton invariant mass obtained with simulated LHC data, and to extract the value of two kinematic endpoints measuring the and the mass differences. This information was used to constrain the MSSM parameter space compatible with the data
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
Theoretical and experimental study of foaming process with chain extended recycled PET
No full textThe theoretical and experimental study of a thermoplastic polymer foaming process is presented. Industrial scraps of PET were used for the production of foamed sheets. The process was performed by making use of a chemical blowing agent (CBA) in the extrusion process. Due to the low intrinsic viscosity of the recycled PET, a chain extender was also used in order to increase the molecular weight of the polymer matrix. Pyromellitic dianhydride (PMDA) and Hydrocerol CT 534 were chosen as chain extender and CBA, respectively. The reactive extrusion and foaming were performed in
a two step process. Rheological characterization was carried out on PET samples previously treated with PMDA, as well as the morphological study was performed to define the cellular structure of the foams produced. Moreover, in order to predict the morphology of the foam, a non isothermal model was developed by taking into account both mass transfer phenomenon and viscous forces effect. Model results were compared with experimental data obtained analyzing the foamed samples. The model was validated in relation to working conditions, chemical blowing agent percentage and initial rheological properties of recycled polymer. A pretty good agreement between experimental and calculated data was achieved
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