1,720,957 research outputs found
On the determination of post-Newtonian parameters with BepiColombo radio science experiment
Full text linkOne of the main goals of the Mercury Orbiter Radio science Experiment (MORE), onboard the ESA-JAXA BepiColombo mission to Mercury, is to perform a test of gravitational theories by means of high precision radio-observables, constraining several Post-Newtonian (PN) parameters. This will be performed in two steps: (i) with a superior solar conjunction experiment during the cruise phase of the mission; (ii) by reconstructing the orbit of Mercury around the Sun once the spacecraft will be arrived at Mercury. In this work we present the results of numerical simulations of the MORE relativity experiment, carried out in a realistic scenario, showing how the experiment can improve over current estimates
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
Augmenting NASA Europa clipper by a small probe: Europa tomography probe (ETP) mission concept
No full textJupiter's moon Europa is widely accepted as one of the most promising environment in the solar system able to sustain extra terrestrial habitability. Compelling evidence for the existence of a subsurface ocean was provided by the magnetic measurements of the Galileo spacecraft. The NASA JPL Europa Clipper mission is scheduled for launch in the 2020s. Because of the harsh Jovian radiation environment and budget limitations, the initial concept of an orbiter was abandoned and the spacecraft will perform only multiple flybys of the moon. Although Clipper will investigate the surface and subsurface properties with a powerful suite of instruments, the new mission profile is not favourable to the investigation of Europa's the deep interior structure. The Clipper project is considering an extra mass of about 250 kg to carry an additional flight element. We propose to augment the mission by including a small spacecraft, the Europa Tomography Probe (ETP), to be deployed on a polar orbit around Europa with a life-time of a few months. ETP will carry a magnetometer and a transponder for inter-satellite link. By exploiting the magnetic induction effect from Jupiter, the magnetometer will measure the Europa's magnetic polarizability, thus providing information on the thickness and conductivity of the internal salty ocean. The ETP transponder will establish a two-way relay link during each flyby, used to transfer telemetry data and to enable range rate measurements onboard Clipper. This configuration minimizes the required power onboard ETP and provides high quality Doppler observables using a simple ultra-stable oscillator hosted on Clipper. The limiting noise in Doppler measurements will be the frequency stability of ETP and relay electronics. Doppler data allow the determination of Europa's static gravity field to high resolution and its variable part due to eccentricity tides (Love number k2). Furthermore, Doppler observables will constrain the Clipper position relative to Europa at a level of a few meters. The precise positioning of the main spacecraft with respect to Europa and the altimetric measurements from the radar REASON can be exploited to measure the tidal displacement (Love number h2) of the outer icy shell. Together, magnetic field, gravity, and possibly altimetric, measurements will place strong constraints on the deep interior structure of Europa and provide a good determination of the ice shell thickness and ocean depth. Despite the simplicity of the proposed configuration, ETP could considerably enhance the overall scientific return of Clipper
Augmenting NASA europa clipper by a small probe: europa tomography probe (ETP) mission concept
No full textThe Jupiter's moon Europa is believed to be one of the few bodies in the Solar System able to host habitable environments. Compelling evidence for the existence of a subsurface ocean was provided by the magnetic field measurements carried out by the Galileo spacecraft. The NASA/JPL Europa Clipper mission is scheduled for launch in the early 2020s. Due to the harsh Jovian radiation environment and budget limitations, the initial concept of an orbiter was abandoned, and the spacecraft will perform only multiple flybys of the moon. Although Clipper will investigate the surface and subsurface properties with a powerful suite of instruments, such approach is not very favourable to a thorough investigation of Europa's deep interior structure. In 2015 the Europa Clipper project announced the possibility to carry an additional flight element with a mass of about 250 kg. We then started investigating a smallest mission aimed at regaining the original science objectives of Clipper for studying the deep interior structure of Europa. Although this additional mass is no longer available, we describe here a mission concept, based on a mothercraft-daughtercraft configuration, which could be of interest to future exploration missions. Our proposal is based on a small spacecraft, the Europa Tomography Probe (ETP), to be inserted in a polar orbit around Europa with a lifetime of a few months. ETP should carry only a magnetometer and a transponder for inter-satellite link, thus not foreseeing any direct link to ground. By exploiting the magnetic induction effect from Jupiter, the magnetometer will measure Europa's magnetic polarizability, thus providing information on the thickness and conductivity of the internal salty ocean, while the ETP transponder will enable a two-way relay link with the mother spacecraft during Europa flybys. The relay link will be used to transfer telemetry data and to carry out range rate measurements on board Clipper. This configuration minimizes the required power on ETP and provides high quality Doppler observables using an ultra-stable oscillator hosted on Clipper. The limiting noise in Doppler measurements will be the frequency stability of ETP and Clipper relay electronics. Doppler data allow the determination of Europa's static gravity field with high resolution along with its variable part due to eccentricity tides (Love number k2). Measurements of the moon's gravity also provide accurate data on its rotational state (e.g., Europa's obliquity and libration amplitude). Furthermore, the inter-satellite Doppler observables can improve the accuracy in the determination of Clipper's position relative to Europa at the level of a few meters in the radial direction. The precise positioning of the main spacecraft relative to Europa and the altimetric measurements from the radar REASON could be exploited to measure the tidal displacement (Love number h2) of the outer icy shell. The NASA's Europa Clipper is viewed as the first applicable study case for the mission concept presented in this paper, which is of general interest to a class of similar flyby missions that can be conceived not only for the Jovian system, but also for Saturn and the ice giants of the solar system, Uranus and Neptune. In the latter case, for example, a small orbiter of Triton could significantly boost the science return from a larger spacecraft focusing on the observation of the planet. In the case of Europa, we show that joint magnetic field, gravity, and possibly altimetric measurements, will place strong constraints on the deep interior structure of the moon and provide a good determination of the ice shell thickness and ocean depth
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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