1,721,210 research outputs found
Searching for the Radiative Decay of the Cosmic Neutrino Background with Line-Intensity Mapping
No full textWe study the possibility to use line-intensity mapping (LIM) to seek photons from the radiative decay of neutrinos in the cosmic neutrino background. The Standard Model prediction for the rate for these decays is extremely small, but it can be enhanced if new physics increases the neutrino electromagnetic moments. The decay photons will appear as an interloper of astrophysical spectral lines. We propose that the neutrinodecay line can be identified with anisotropies in LIM clustering and also with the voxel intensity distribution. Ongoing and future LIM experiments will have-depending on the neutrino hierarchy, transition, and experiment considered-a sensitivity to an effective electromagnetic transition moment similar to 10(-12) - 10(-8) (m(i)c(2)/0.1 eV)(3/2)mu(B), where m(i) is the mass of the decaying neutrino and mu(B) is the Bohr magneton. This will be significantly more sensitive than cosmic microwave background spectral distortions, and it will be competitive with stellar cooling studies. As a by-product, we also report an analytic form of the one-point probability distribution function for neutrino-density fluctuations, obtained from the QUIJOTE simulations using symbolic regression
Red Density Perturbations and Inflationary Gravitational Waves
Full text linkWe study the implications of recent indications for a red spectrum of primordial density perturbations for the detection of inflationary gravitational waves (IGWs) with forthcoming cosmic microwave background experiments. We find that if inflation occurs with a single field with an inflaton potential minimized at V=0, then Planck will be able to detect IGWs at better than 2 confidence level, unless the inflaton potential is a power law with a very weak power. The proposed satellite missions of the Cosmic Vision and Inflation Probe programs will be able to detect IGWs from all the models we have surveyed at better than 5 confidence level. We provide an example of what is required if the IGW background is to remain undetected even by these latter experiments.We study the implications of recent indications for a red spectrum of primordial density perturbations for the detection of inflationary gravitational waves (IGWs) with forthcoming cosmic microwave background experiments. We find that if inflation occurs with a single field with an inflaton potential minimized at V=0, then Planck will be able to detect IGWs at better than 2 confidence level, unless the inflaton potential is a power law with a very weak power. The proposed satellite missions of the Cosmic Vision and Inflation Probe programs will be able to detect IGWs from all the models we have surveyed at better than 5 confidence level. We provide an example of what is required if the IGW background is to remain undetected even by these latter experiments
Seeking dark matter with γ -ray attenuation
No full textThe flux of high-energy astrophysical gamma rays is attenuated by the production of electron-positron pairs from scattering off of extragalactic background light (EBL). We use the most up-to-date information on galaxy populations to compute their contributions to the pair-production optical depth. We find that the optical depth inferred from gamma-ray measurements exceeds that expected from galaxies at the similar to 2 sigma level. If the excess is modeled as a frequency-independent re-scaling of the standard contribution to the EBL from galaxies, then an excess (an overall 14-30% increase of the EBL) is favored over the null hypothesis of no excess at the 2.7 sigma level. If the frequency dependence of the excess is instead modeled as a two-photon decay of a dark-matter axion, then the excess is favored over the null hypothesis at the 2.1 sigma confidence level. While we find no evidence for a dark-matter signal, the analysis sets the strongest current bounds on the photon-axion coupling over the 8-25 eV mass range. This work highlights the sensitivity of gamma-ray optical depth measurements to ALPs, which is expected to improve with new observatories and better EBL determinations from future observations
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
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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