Imperial College London

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.

Plasmonic nanoantennas: fundamentals and their use in controlling the radiative properties of nanoemitters.

Abstract: When light interacts with a metal nanoparticle (NP), its conduction electrons can be driven by the incident electric field in collective oscillations known as localized surface plasmon resonances (LSPRs). These give rise to a drastic alteration of the incident radiation pattern and to striking effects such as the subwavelength localization of electromagnetic (EM) energy, the formation of high intensity hot spots at the NP surface, or the directional scattering of light out of the structure. LSPRs can also couple to the EM fields emitted by molecules, atoms, or quantum dots placed in the vicinity of the NP, leading in turn to a strong modification of the radiative and nonradiative properties of the emitter. Since LSPRs enable an efficient transfer of EM energy from the near to the far-field of metal NPs and vice versa, we can consider plasmonic nanostructures as nanoantennas, because they operate in a similar way to radio antennas but at higher frequencies. Typically, plasmonic nanoantennas at optical frequencies are made of gold and silver due to their goodmetallic properties and low absorption. Controlling and guiding light has been one of science’s most influential achievements. It affects everyday life in many ways, such as the development of telescopes, microscopes, spectrometers, and optical fibers, to name but a few. These examples exploit the wave nature of light and are based on the reflection, refraction and diffraction of light by optical elements such as mirrors, lenses or gratings. However, the wave nature of light limits the resolution to which an object can be imaged, as well as the size of the transverse cross section of efficient guiding structures to the wavelength dimension. Plasmonic resonances in nanoantennas overcome these constraints, allowing unprecedented control of light-matter interactions within subwavelength volumes (i.e., within the nanoscale at optical frequencies). Such properties have attracted much interest lately, due to the implications they have both in fundamental research and in technological applications. Metal NPs have been used since antiquity. Due to their strong scattering properties in the visible range, they show attractive colors. One of their first applications, dating back to the Roman Empire more than 2000 years ago, was as a colorant for clothing. In art, they were used to stain window glass and ceramics. Obviously, it was not known then that the colorants being used contained metal NPs or that the spectacular colors were due to the excitation of LSPRs. The first reported intentional production of metal NPs dates from 1857, when Faraday synthesized gold colloids. However, at the time there was not much interest in understanding the physics behind the optical properties of colloids due to the impossibility of synthesizing NPs with well-controlled shapes and sizes, as well as the lack of accurate detection techniques. The first theoretical work on the scattering of light by particles smaller than the incident wavelength was carried out by Lord Rayleigh at the end of the 19th century. He analyzed the diffusion of light by diluted gases, and his theory explained physical phenomena such as the blueness of the sky, the redness of the sunset, or the yellow color of the sun. Mie took the next step forward by deriving an analytical solution to Maxwell’s equations to describe the interaction of light with spheres of arbitrary radius and composition. Subsequently, based on the results of Rayleigh and Mie, Gans considered elliptical geometries. He demonstrated that the optical response of metal NPs is

Early-onset Alzheimer's disease caused by mutations at codon 717 of the β-amyloid precursor protein gene

Abstract: A MUTATION at codon 717 of the β-amyloid precursor protein gene has been found to cosegregate with familial Alzheimer's disease in a single family1. This mutation has been reported in a further five out of ∼ 100 families multiply affected by Alzheimer's disease1–4. We have identified another family, F19, in which we have detected linkage between the β-amyloid precursor protein gene and Alzheimer's disease. Direct sequencing of exon 17 (ref. 5) in affected individuals from this family has revealed a base change producing a Val → Gly substitution, also at codon 717. The occurrence of a second allelic variant at codon 717 linked to the Alzheimer's phenotype supports the hypothesis that they are pathogenic mutations.

Prion Diseases of Humans and Animals: Their Causes and Molecular Basis

Abstract: ▪ Abstract Prion diseases are transmissible neurodegenerative conditions that include Creutzfeldt-Jakob disease (CJD) in humans and bovine spongiform encephalopathy (BSE) and scrapie in animals. Prions appear to be composed principally or entirely of abnormal isoforms of a host-encoded glycoprotein, prion protein. Prion propagation involves recruitment of host cellular prion protein, composed primarily of α-helical structure, into a disease specific isoform rich in β-sheet structure. The existence of multiple prion strains has been difficult to explain in terms of a protein-only infections agent, but recent studies suggest that strain specific phenotypes can be encoded by different prion protein conformations and glycosylation patterns. The ability of a protein to encode phenotypic information has important biological implications. The appearance of a novel human prion disease, variant CJD, and the clear experimental evidence that it is caused by exposure to BSE has highlighted the need to understand the ...

JASPAR 2018: update of the open-access database of transcription factor binding profiles and its web framework

Abstract: JASPAR (http://jaspar.genereg.net) is an open-access database of curated, non-redundant transcription factor (TF)-binding profiles stored as position frequency matrices (PFMs) and TF flexible models (TFFMs) for TFs across multiple species in six taxonomic groups. In the 2018 release of JASPAR, the CORE collection has been expanded with 322 new PFMs (60 for vertebrates and 262 for plants) and 33 PFMs were updated (24 for vertebrates, 8 for plants and 1 for insects). These new profiles represent a 30% expansion compared to the 2016 release. In addition, we have introduced 316 TFFMs (95 for vertebrates, 218 for plants and 3 for insects). This release incorporates clusters of similar PFMs in each taxon and each TF class per taxon. The JASPAR 2018 CORE vertebrate collection of PFMs was used to predict TF-binding sites in the human genome. The predictions are made available to the scientific community through a UCSC Genome Browser track data hub. Finally, this update comes with a new web framework with an interactive and responsive user-interface, along with new features. All the underlying data can be retrieved programmatically using a RESTful API and through the JASPAR 2018 R/Bioconductor package.

Allergy and allergic diseases.

Abstract: Allergic Diseases and Their Treatment Allergic Rhinitis Allergic rhinitis is characterized by episodes of sneezing, itching, rhinorrhea, and nasal obstruction. Perennial allergic rhinitis should be distinguished from nonallergic, noninfectious forms of rhinitis, such as idiopathic (“vasomotor”) rhinitis, nonallergic rhinitis with eosinophilia syndrome, hormonal rhinitis, drug-induced rhinitis, and food-induced rhinitis. The treatment of allergic rhinitis (and other allergic diseases) consists of allergen avoidance (whenever possible and practical), antiallergic medication, and immunotherapy for specific allergens, which is also called hyposensitization or desensitization. Currently, the drugs usually used to treat allergic rhinitis are antihistamines and anticholinergic agents (for the relief of symptoms) and . . .