1,721,575 research outputs found
DISPOSITIVO E SISTEMA DI RIVELAZIONE DI RADIAZIONI EMESSE DA UN CAMPIONE IRRAGGIATO CON UN FASCIO DI ECCITAZIONE
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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
Magneto-optical measurements in thin film of frequency dependence of hysteresis loops from 10 mHz to 10 kHz
No full textTheoretical comparison between two different filtering techniques suitable for the VLSI spectroscopic amplifier ROTOR
No full textThe development of new detection systems based on arrays of Silicon Drift Detectors (SDD) used for new X-ray spectroscopy applications, like X-ray Holography and EXAFS experiments, requires the realization of suitable integrated low-noise electronics for the readout of the detector signals. Recently, a new VLSI time-variant signal processor called ROTOR has been developed. Despite its time-variant nature ROTOR is capable of correctly processing events randomly distributed along the time axis, thanks to the employment of the Concurrent Wheel Technique (CWT). Two different possible solutions for the ROTOR chip have been developed, both suitable for the CWT working mechanism. A theoretical comparison between the noise performances of the two filtering methods has been carried out and is presented in this work. © 2003 Elsevier B.V. All rights reserved
A 8-channels low-noise CMOS readout circuit for silicon detectors with on-chip front-end JFET
No full textWe propose a CMOS circuit designed to be used with silicon drift detectors (SDDs) coupled to scintillators for /spl gamma/-ray imaging applications. The circuit is composed by 8 analog channels, each including a low-noise preamplifier, a 6th order semiGaussian shaping amplifier with four selectable peaking times from 1.8 /spl mu/s up to 6 /spl mu/s, a peak stretcher and a baseline holder. The integrated time constant used for the shaping are implemented by means of a recently proposed 'RC' cell. This cell is based on the de-magnification of the current flowing in a resistor R by means of the use of current mirrors. The 8 analog channels of the chip are multiplexed to a single analog output. A suitable digital section provides self-resetting of the channels, trigger output and the programming of independent threshold on the analog channels by means of a programmable serial register and 3-bit DACs. In this work, the main features of the circuit are first presented. The experimental results obtained in the characterization of the prototype are then reported and discussed. The energy resolution measured using a single channel of the chip with a silicon drift detector droplet (SDD/sup 3/) is of 128 eV at 6 keV with the detector cooled at -20/spl deg/C
An 8-channel DRAGO readout circuit for silicon detectors with integrated front-end JFET
No full textWe have developed a CMOS circuit to be used with Silicon Drift Detectors (SDDs) for X-ray spectroscopy and γ-ray imaging applications. The circuit operates with the input transistor integrated directly on the detector wafer. The circuit is composed of 8 analog channels, each including a low-noise voltage preamplifier, a 6th order semi-Gaussian shaping amplifier, with four selectable peaking times from 1.8 μs up to 6 μs, and a peak stretcher. The integrated time constant used for the shaping are implemented by means of a recently proposed 'RC' cell. This cell is based on the de-magnification of the current flowing in a resistor R thanks to the use of current mirrors. The 8 analog channels of the chip are multiplexed to a single analog output. A digital section provides self-resetting of the channels, trigger output and the external programming of independent threshold on the analog channels by means of a 3 bit DAC and a programmable serial register. In this work, the main features of the circuit are described. The measurement results obtained in the characterization of the prototype are then reported and discussed. The energy resolution measured using a single channel of the chip with a Silicon Drift Detector Droplet (SDD 3) is of 128 eV at 6 keV with the detector cooled at -20°C. Spectroscopy measurements using a multi-element SDD are also shown. © 2006 IEEE
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
TERA: Throughput-Enhanced Readout ASIC for High-Rate Energy-Dispersive X-Ray Detection
No full textThis work presents throughput-enhanced readout ASIC (TERA), an integrated multichannel analog pulse processor (APP), suitable for processing signals generated from solid-state detectors, such as silicon drift detectors (SDDs) coupled to pulsed reset-type charge-sensitive amplifiers (CSAs). In particular, this development targets applications at high count rates (≈Mcps) in energy-dispersive X-ray spectroscopy. The demonstrator chip is composed of four parallel readout channels. Each channel includes a seventh-order semi-Gaussian shaping amplifier with controllable shaping times and full-scale ranges, followed by a peak stretcher and switched-capacitor analog memory. Each channel is also equipped with a dedicated peak detector and a novel pile-up rejection (PUR) logic. Each pair of channels can be optionally digitized by a 12-bit on-chip successive-approximation-register (SAR) analog-to-digital converter (ADC), providing a digital output at a maximum sampling rate of 2.5 Msps. The architecture achieves high throughput and satisfactory energy resolution. In fact, in 55Fe spectroscopy measurements, when using the shortest shaping pulsewidth of 200 ns, a full-width at half-maximum (FWHM) Mn Kα line of 159.4 eV (12.5 e-rms ) was obtained at low rates (10 kcps). This energy resolution can be achieved, thanks to the minimization of the effect of the ballistic deficit, achieved by optimizing the SDD detector in terms of optimum biasing, low operating temperature (-37 °C), and small size (1-mm diameter). At 1.61 Mcps/channel input rate, an output count rate of 1.09 Mcps/channel and a resolution of 205.1 eV (19.7 e-rms) were achieved with a 4-mm-diameter SDD and optimum PUR settings. Simultaneous multichannel acquisition has been successfully performed. Such high-rate performances are, to our knowledge, the best ones reported so far for an APP, based on a spectroscopy-grade application-specific integrated circuit (ASIC), and very close to those achievable by a standard digital pulse processor (DPP). Therefore, TERA can represent an attractive, compact, and scalable pulse processing solution for high-rate multichannel energy-dispersive X-ray detection systems
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