1,721,165 research outputs found
Application of Machine and Deep Learning Methods to the Analysis of IACTs Data
No full textThe Imaging Atmospheric Cherenkov technique opened a previously inaccessible window for the study of astrophysical sources of radiation in the very high-energy regime (TeV) and is playing a significant role in the discovery and characterization of very high-energy gamma-ray emitters. However, the data collected by Imaging Atmospheric Cherenkov Telescopes (IACTs) are highly dominated, even for the most powerful sources, by the overwhelming background due to cosmic-ray nuclei and cosmic-ray electrons. For this reason, the analysis of IACTs data demands a highly efficient background rejection technique able to discriminate gamma-ray induced signal. On the other hand, the analysis of ring images produced by muons in an IACT provides a powerful and precise method to calibrate the overall optical throughput and monitor the telescope optical point-spread function. A robust muon tagger to collect large and highly pure samples of muon events is therefore required for calibration purposes. Gamma/hadron discrimination and muon tagging through Machine and Deep Learning techniques are the main topics of the present work
CoMo catalysts supported on aluminosilicates: synergy between support and sodium effects”
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Implication of the thermal origin of the soft excess in Seyfert 1 galaxies
No full textWe present a study of the soft X-ray properties of a sample of 15 Seyfert 1 observed with ASCA. The spectrum of 11 objects in the sample shows a soft excess over a single power-law model. We found that the best interpretation of this excess is a thermal radiation coming from the innermost region of an accretion disc. Indeed the use of a black body model gives a good fit in 9 sources out of the 11 that show the excess. However the temperatures obtained from the best fit are higher than those expected if the emission comes from a region just outside the last stable orbit around a non-rotating black hole (Schwarzschild black hole). The temperatures obtained seem to indicate that the emission region is closer than three Schwarzschild radii, suggesting the presence of a Kerr (rotating) black hole
Coupling chemical reaction to electrospray: a novel preparation of gold nanostructures
No full textThe simultaneous reduction of Au(III) to Au(0), synthesis of gold nanoparticles and their deposition onto boron-doped silicon target have been attained by the electrospray technique. In this way the overall process can be considered as a novel chemical/physical hybrid method which synergically exploits the merits of both approaches. Various experimental conditions have been explored to optimize the process: it has been found that, by applying a negative high voltage to the boron-doped silicon target and with the presence of the surfactant Bis(2-ethylhexyl)sulfosuccinate sodium salt in the solution, a quantitative transformation of Au(III) to Au(0) nanoparticles has been obtained. The deposited nanoparticles structure has been studied by Wide Angle X-Ray Scattering. The molecular processes underlying the simultaneous gold reduction and nanoparticle deposition have been discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
eta1-Allypalladium complexes with tridentate PNP’ ligand for the assembly of modified Screen Printed Electrodes: an electrochemical study.
No full textSpecific Pd-based organometallic complex, in particular the [Pd(η1-CH2–CH=CH2)(P–N–P’)]BF4 was used for the assembly of chemically modified Screen Printed Electrodes (SPEs) and their electrochemical reactivity was also investigated. For this purpose potassium ferricyanide, hexaammineruthenium(III) chloride, sodium hexachloroiridate-(III) hydrate, ascorbic acid (AA), uric acid (UA), acetaminophen (Ac), guanine (G) and adenine (A) were used to study the electron-transfer processes, which occurred at modified SPEs, fabricated by using the [Pd(η1-CH2–CH=CH2)(P–N–P’)]BF4, applying the drop casting procedure. Interesting results were obtained in the case of the guanine (G) quantitative detection, especially in terms of a wide range of concentration (2.5-40 nM), an high sensitivity (of 49.0 A M-1 cm-2), a low detection limit (L.O.D.= 1.0nM) and a fast response time (of t=2s). The intra-electrode reproducibility (RSD%) was <1% for the same SPE used for each point of the calibration plot. The inter-electrode reproducibility (RSD%), estimated by using different SPEs for each single point of the quantitative calibration graph, ranging from 5 to 10%, better than that exhibited by other different chemical sensors, described in literature, and reported in this work for comparison. In addition, the high selectivity of the chemically modified sensors toward the oxidation of guanine, exhibited in presence of a mixture of nucleic acids (G + A, in the same electrochemical bath solution) could be related to the different electro-catalytic mechanisms, as demonstrated by the XPS study. This chemical sensor prototype could be very promising for bio-medicine applications, as the early detection of some kind of cancer diseases
Variations on the Author
Get PDF“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
Get PDFWe 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
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