There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of $1.0 \times 10^{-21}$. It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203 000 years, equivalent to a significance greater than 5.1 {\sigma}. The source lies at a luminosity distance of $410^{+160}_{-180}$ Mpc corresponding to a redshift $z = 0.09^{+0.03}_{-0.04}$. In the source frame, the initial black hole masses are $36^{+5}_{-4} M_\odot$ and $29^{+4}_{-4} M_\odot$, and the final black hole mass is $62^{+4}_{-4} M_\odot$, with $3.0^{+0.5}_{-0.5} M_\odot c^2$ radiated in gravitational waves. All uncertainties define 90% credible intervals.These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

https://physics.aps.org/featured-article-pdf/10.1103/PhysRevLett.116.061102

Observation of Gravitational Waves from a Binary Black Hole Merger

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

On August 17, 2017 at 12∶41:04 UTC the Advanced LIGO and Advanced Virgo gravitational-wave detectors made their first observation of a binary neutron star inspiral. The signal, GW170817, was detected with a combined signal-to-noise ratio of 32.4 and a false-alarm-rate estimate of less than one per 8.0×10^{4}  years. We infer the component masses of the binary to be between 0.86 and 2.26  M_{⊙}, in agreement with masses of known neutron stars. Restricting the component spins to the range inferred in binary neutron stars, we find the component masses to be in the range 1.17-1.60  M_{⊙}, with the total mass of the system 2.74_{-0.01}^{+0.04}M_{⊙}. The source was localized within a sky region of 28  deg^{2} (90% probability) and had a luminosity distance of 40_{-14}^{+8}  Mpc, the closest and most precisely localized gravitational-wave signal yet. The association with the γ-ray burst GRB 170817A, detected by Fermi-GBM 1.7 s after the coalescence, corroborates the hypothesis of a neutron star merger and provides the first direct evidence of a link between these mergers and short γ-ray bursts. Subsequent identification of transient counterparts across the electromagnetic spectrum in the same location further supports the interpretation of this event as a neutron star merger. This unprecedented joint gravitational and electromagnetic observation provides insight into astrophysics, dense matter, gravitation, and cosmology.

/pdf/gw170817-observation-of-gravitational-waves-from-a-binary-q2x9byg981.pdf

GW170817: observation of gravitational waves from a binary neutron star inspiral

Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.

/pdf/climate-change-2007-the-physical-science-basis-1x93ttz9jt.pdf

Climate Change 2007: The Physical Science Basis.

Resume Cet article presente les resultats d’une etude de terrain (enquete d’usage) portant sur les caracteristiques des Situations d’Apprentissage Collectives Instrumentees (SACI) dans l’enseignement superieur selon le point de vue des acteurs (concepteur et tuteur) qui ont participe a leur conception ou a leur utilisation avec des etudiants. Notre propos est de determiner les formes que prennent les SACI (en termes de scenario, d’outils, de type d’activite...) et les demarches pedagogiques mises en pratique par les acteurs enseignants. Nous detaillons les resultats de notre etude, faisant principalement ressortir une demarche « artisanale » des acteurs, c’est-a-dire fondee sur une utilisation opportuniste et pragmatique des outils disponibles pour s’adapter aux contextes de formation.

/pdf/activites-collectives-et-instrumentation-etude-de-pratiques-n6cinbrxa1.pdf

Activités collectives et instrumentation : étude de pratiques dans l'enseignement supérieur

Actuellement, les activites collectives sont de plus en plus souvent supportees par des plates-formes educatives qui proposent de nombreux outils de communication, de production, de partage et de management du travail collectif. Mais il n'est pas garanti que la mise a disposition des ces outils aux acteurs (concepteurs, tuteurs et apprenants) implique leur reelle utilisation. Notre travail, par une etude de terrain, dresse un bilan des caracteristiques des situations d'apprentissage collectives instrumentees (SACI) dans l'enseignement superieur. Notre propos est de determiner : si les SACI existent ; quelle forme elles prennent (en termes de scenario, d'outils, de type d'activite...) ; si les recommandations issues de travaux de recherche sont mises en pratique par les concepteurs pedagogiques et si les activites prescrites par ces concepteurs se deroulent comme prevu avec les apprenants et les tuteurs ? Pour repondre a ces questions, nous nous basons plus particulierement sur des enquetes d'usage aupres des acteurs de SACI.

Situations d'apprentissage collectives instrumentées : étude de pratiques dans l'enseignement supérieur

Cet article presente une evaluation des conditions d’usage d’un ENT (appele ONE) par des enseignants du primaire. Elle est realisee a travers deux etudes utilisant la theorie de l’activite comme cadre d’analyse. La premiere evalue les activites reelles effectuees par les enseignants sur l’ENT en analysant thematiquement le contenu des publications faites sur l’ENT, afin de comprendre comment les utilisateurs s’approprient l’outil. La seconde evalue les facteurs d’acceptation et de refus de la technologie, en decrivant la maniere dont les enseignants vivent et percoivent le role que l’ENT peut jouer sur l’evolution de leurs pratiques professionnelles (en les maintenant, les transformant ou les restreignant). Ces etudes ont permis de montrer que l’appropriation de ONE s’est produite notamment a travers les activites pedagogiques et de communication avec les parents d’eleves. L’acceptation favorable de cet ENT est due a la facilite d’usage et l’adequation de l’interface aux enseignants et jeunes enfants.

https://hal.archives-ouvertes.fr/hal-01512377/document

L’acceptation et l’appropriation des ENT (Espaces Numériques de Travail) par les enseignants du primaire

Immersion de la personne âgée en maison de retraite : étude des incidences possibles des TIC dans sa (re)construction psychosociale

Marine mammal biodiversity and rare narwhal ( Monodon monoceros ) observations near northern Ellesmere Island, Canada

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Christine Michel

Author Tools

Chat about Author