Institution
Imperial College London
Education•London, Westminster, United Kingdom•
About: Imperial College London is a education organization based out in London, Westminster, United Kingdom. It is known for research contribution in the topics: Population & Medicine. The organization has 90019 authors who have published 209164 publications receiving 9337534 citations. The organization is also known as: Imperial College of Science, Technology and Medicine & Imperial College.
Topics: Population, Medicine, Context (language use), Cancer, Computer science
Papers published on a yearly basis
Papers
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TL;DR: In this paper, a theoretical framework for understanding plasma turbulence in astrophysical plasmas is presented, motivated by observations of electromagnetic and density fluctuations in the solar wind, interstellar medium and galaxy clusters, as well as by models of particle heating in accretion disks.
Abstract: This paper presents a theoretical framework for understanding plasma turbulence in astrophysical plasmas. It is motivated by observations of electromagnetic and density fluctuations in the solar wind, interstellar medium and galaxy clusters, as well as by models of particle heating in accretion disks. All of these plasmas and many others have turbulent motions at weakly collisional and collisionless scales. The paper focuses on turbulence in a strong mean magnetic field. The key assumptions are that the turbulent fluctuations are small compared to the mean field, spatially anisotropic with respect to it and that their frequency is low compared to the ion cyclotron frequency. The turbulence is assumed to be forced at some system-specific outer scale. The energy injected at this scale has to be dissipated into heat, which ultimately cannot be accomplished without collisions. A kinetic cascade develops that brings the energy to collisional scales both in space and velocity. The nature of the kinetic cascade in various scale ranges depends on the physics of plasma fluctuations that exist there. There are four special scales that separate physically distinct regimes: the electron and ion gyroscales, the mean free path and the electron diffusion scale. In each of the scale ranges separated by these scales, the fully kinetic problem is systematically reduced to a more physically transparent and computationally tractable system of equations, which are derived in a rigorous way. In the inertial range above the ion gyroscale, the kinetic cascade separates into two parts: a cascade of Alfvenic fluctuations and a passive cascade of density and magnetic-field-strength fluctuations. The former are governed by the reduced magnetohydrodynamic (RMHD) equations at both the collisional and collisionless scales; the latter obey a linear kinetic equation along the (moving) field lines associated with the Alfvenic component (in the collisional limit, these compressive fluctuations become the slow and entropy modes of the conventional MHD). In the dissipation range below ion gyroscale, there are again two cascades: the kinetic-Alfven-wave (KAW) cascade governed by two fluid-like electron reduced magnetohydrodynamic (ERMHD) equations and a passive cascade of ion entropy fluctuations both in space and velocity. The latter cascade brings the energy of the inertial-range fluctuations that was Landau-damped at the ion gyroscale to collisional scales in the phase space and leads to ion heating. The KAW energy is similarly damped at the electron gyroscale and converted into electron heat. Kolmogorov-style scaling relations are derived for all of these cascades. The relationship between the theoretical models proposed in this paper and astrophysical applications and observations is discussed in detail.
853 citations
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TL;DR: This paper extends the standard mean-variance portfolio optimisation model to include cardinality constraints that limit a portfolio to have a specified number of assets, and to impose limits on the proportion of the portfolio held in a given asset.
853 citations
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University of Sussex1, Jet Propulsion Laboratory2, California Institute of Technology3, European Space Agency4, Ames Research Center5, University of Edinburgh6, Paris Diderot University7, Imperial College London8, University of Paris-Sud9, Aix-Marseille University10, Cornell University11, Spanish National Research Council12, University of La Laguna13, Complutense University of Madrid14, UK Astronomy Technology Centre15, University of Colorado Boulder16, University of California, Irvine17, Goddard Space Flight Center18, University of Nottingham19, Cardiff University20, University of Padua21, Institut d'Astrophysique de Paris22, University of Cambridge23, University of British Columbia24, European Space Research and Technology Centre25, University of Manchester26, University College London27, Rutherford Appleton Laboratory28, University of Lethbridge29, University of Oxford30, Commonwealth Scientific and Industrial Research Organisation31, University of Hertfordshire32, Harvard University33
TL;DR: The Herschel Multi-tiered Extragalactic Survey (HerMES) is a legacy program designed to map a set of nested fields totalling ∼380deg^2 as mentioned in this paper.
Abstract: The Herschel Multi-tiered Extragalactic Survey (HerMES) is a legacy programme designed to map a set of nested fields totalling ∼380 deg^2. Fields range in size from 0.01 to ∼20 deg^2, using the Herschel-Spectral and Photometric Imaging Receiver (SPIRE) (at 250, 350 and 500 μm) and the Herschel-Photodetector Array Camera and Spectrometer (PACS) (at 100 and 160 μm), with an additional wider component of 270 deg^2 with SPIRE alone. These bands cover the peak of the redshifted thermal spectral energy distribution from interstellar dust and thus capture the reprocessed optical and ultraviolet radiation from star formation that has been absorbed by dust, and are critical for forming a complete multiwavelength understanding of galaxy formation and evolution.
The survey will detect of the order of 100 000 galaxies at 5σ in some of the best-studied fields in the sky. Additionally, HerMES is closely coordinated with the PACS Evolutionary Probe survey. Making maximum use of the full spectrum of ancillary data, from radio to X-ray wavelengths, it is designed to facilitate redshift determination, rapidly identify unusual objects and understand the relationships between thermal emission from dust and other processes. Scientific questions HerMES will be used to answer include the total infrared emission of galaxies, the evolution of the luminosity function, the clustering properties of dusty galaxies and the properties of populations of galaxies which lie below the confusion limit through lensing and statistical techniques.
This paper defines the survey observations and data products, outlines the primary scientific goals of the HerMES team, and reviews some of the early results.
852 citations
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TL;DR: Mechanistic insights into oxygen-induced photodegradation of perovskite films are reported, finding fast oxygen diffusion into CH3NH3PbI3 films is accompanied by photo-induced formation of highly reactive superoxide species from oxygen.
Abstract: Methylammonium lead halide perovskites are attracting intense interest as promising materials for next-generation solar cells, but serious issues related to long-term stability need to be addressed. Perovskite films based on CH3NH3PbI3 undergo rapid degradation when exposed to oxygen and light. Here, we report mechanistic insights into this oxygen-induced photodegradation from a range of experimental and computational techniques. We find fast oxygen diffusion into CH3NH3PbI3 films is accompanied by photo-induced formation of highly reactive superoxide species. Perovskite films composed of small crystallites show higher yields of superoxide and lower stability. Ab initio simulations indicate that iodide vacancies are the preferred sites in mediating the photo-induced formation of superoxide species from oxygen. Thin-film passivation with iodide salts is shown to enhance film and device stability. The understanding of degradation phenomena gained from this study is important for the future design and optimization of stable perovskite solar cells.
850 citations
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University of Crete1, National and Kapodistrian University of Athens2, University of Paris3, Leiden University Medical Center4, Radboud University Nijmegen5, University of Barcelona6, Charité7, University of Padua8, RWTH Aachen University9, Cliniques Universitaires Saint-Luc10, Stanford University11, University College London12, University Medical Center Groningen13, Imperial College London14, Great Ormond Street Hospital15, University of Genoa16, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico17, Complutense University of Madrid18, University of Düsseldorf19, Charles University in Prague20, University of Porto21, Karolinska University Hospital22, Hannover Medical School23, University of Birmingham24
TL;DR: Recommendations for the management of lupus nephritis were developed using an evidence-based approach followed by expert consensus and there is no evidence to suggest that management of LN should differ in children versus adults.
Abstract: Objectives To develop recommendations for the management of adult and paediatric lupus nephritis (LN).
849 citations
Authors
Showing all 90798 results
Name | H-index | Papers | Citations |
---|---|---|---|
Albert Hofman | 267 | 2530 | 321405 |
David Miller | 203 | 2573 | 204840 |
Tamara B. Harris | 201 | 1143 | 163979 |
Mark I. McCarthy | 200 | 1028 | 187898 |
Peter J. Barnes | 194 | 1530 | 166618 |
Simon D. M. White | 189 | 795 | 231645 |
Patrick W. Serruys | 186 | 2427 | 173210 |
John Hardy | 177 | 1178 | 171694 |
Simon Baron-Cohen | 172 | 773 | 118071 |
Richard H. Friend | 169 | 1182 | 140032 |
Yang Gao | 168 | 2047 | 146301 |
Hongfang Liu | 166 | 2356 | 156290 |
Philippe Froguel | 166 | 820 | 118816 |
Salvador Moncada | 164 | 495 | 138030 |
Dennis R. Burton | 164 | 683 | 90959 |