Fast High-Responsivity Few-Layer MoTe2 Photodetectors

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.The Transition Metal Dichalcogenide MoTe2 is fabricated via mechanical exfoliation into few-layer Field Effect Transistors (FETs) having a hole mobility of 2.04 V/cm2/s. Four-layer MoTe2 FETs show a high photoresponsivity of 6 A/W and a response time, at around 160 μs, over 100 times faster than previously reported for MoTe2. Few-layer MoTe2 thus appears as a strong candidate for high speed and high sensitivity photodetection applications.CDW would like to acknowledge funding via EPSRC grants EP/M015173/1 and EP/M015130/1. TJO acknowledges funding from the EPSRC Centre for Doctoral Training in Metamaterials, grant number EP/L015331/

Avoiding catastrophic failure in correlated networks of networks

Networks in nature do not act in isolation but instead exchange information, and depend on each other to function properly. An incipient theory of Networks of Networks have shown that connected random networks may very easily result in abrupt failures. This theoretical finding bares an intrinsic paradox: If natural systems organize in interconnected networks, how can they be so stable? Here we provide a solution to this conundrum, showing that the stability of a system of networks relies on the relation between the internal structure of a network and its pattern of connections to other networks. Specifically, we demonstrate that if network inter-connections are provided by hubs of the network and if there is a moderate degree of convergence of inter-network connection the systems of network are stable and robust to failure. We test this theoretical prediction in two independent experiments of functional brain networks (in task- and resting states) which show that brain networks are connected with a topology that maximizes stability according to the theory.Comment: 40 pages, 7 figure

Imaging spontaneous currents in superconducting arrays of pi-junctions

Superconductors separated by a thin tunneling barrier exhibit the Josephson effect that allows charge transport at zero voltage, typically with no phase shift between the superconductors in the lowest energy state. Recently, Josephson junctions with ground state phase shifts of pi proposed by theory three decades ago have been demonstrated. In superconducting loops, pi-junctions cause spontaneous circulation of persistent currents in zero magnetic field, analogous to spin-1/2 systems. Here we image the spontaneous zero-field currents in superconducting networks of temperature-controlled pi-junctions with weakly ferromagnetic barriers using a scanning SQUID microscope. We find an onset of spontaneous supercurrents at the 0-pi transition temperature of the junctions Tpi = 3 K. We image the currents in non-uniformly frustrated arrays consisting of cells with even and odd numbers of pi-junctions. Such arrays are attractive model systems for studying the exotic phases of the 2D XY-model and achieving scalable adiabatic quantum computers.Comment: Pre-referee version. Accepted to Nature Physic

Effects of ocean acidification on invertebrate settlement at volcanic CO<inf>2</inf> vents

We present the first study of the effects of ocean acidification on settlement of benthic invertebrates and microfauna. Artificial collectors were placed for 1 month along pH gradients at CO2 vents off Ischia (Tyrrhenian Sea, Italy). Seventy-nine taxa were identified from six main taxonomic groups (foraminiferans, nematodes, polychaetes, molluscs, crustaceans and chaetognaths). Calcareous foraminiferans, serpulid polychaetes, gastropods and bivalves showed highly significant reductions in recruitment to the collectors as pCO2 rose from normal (336-341 ppm, pH 8.09-8.15) to high levels (886-5,148 ppm) causing acidified conditions near the vents (pH 7.08-7.79). Only the syllid polychaete Syllis prolifera had higher abundances at the most acidified station, although a wide range of polychaetes and small crustaceans was able to settle and survive under these conditions. A few taxa (Amphiglena mediterranea, Leptochelia dubia, Caprella acanthifera) were particularly abundant at stations acidified by intermediate amounts of CO2 (pH 7. 41-7.99). These results show that increased levels of CO2 can profoundly affect the settlement of a wide range of benthic organisms. © 2010 Springer-Verlag

Humidity‐Controlled Ultralow Power Layer‐by‐Layer Thinning, Nanopatterning and Bandgap Engineering of MoTe2

This is the final version. Available on open access from Wiley via the DOI in this recordA highly effective laser thinning method is demonstrated to accurately control the thickness of MoTe2 layers. By utilizing the humidity present in the ambient atmosphere, multilayered MoTe2 films can be uniformly thinned all the way down to monolayer with layer-by-layer precision using an ultralow laser power density of 0.2 mW µm−2. Localized bandgap engineering is also performed in MoTe2, by creating regions with different bandgaps on the same film, enabling the formation of lateral homojunctions with sub-200 nm spatial resolution. Field-effect transistors fabricated from these thinned layers exhibit significantly improved electrical properties with an order of magnitude increase in on/off current ratios, along with enhancements in on-current and field-effect mobility values. Thinned devices also exhibit the fastest photoresponse (45 µs) for an MoTe2-based visible photodetector reported to date, along with a high photoresponsivity. A highly sensitive monolayer MoTe2 photodetector is also reported. These results demonstrate the efficiency of the presented thinning approach in producing high-quality MoTe2 films for electronic and optoelectronic applications.Office of Naval Research GlobalEngineering and Physical Sciences Research Council (EPSRC)Defence Science and Technology Laborator

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

Predictive habitat suitability models to aid conservation of elasmobranch diversity in the central Mediterranean Sea

Commercial fisheries have dramatically impacted elasmobranch populations worldwide. With high capture and bycatch rates, the abundance of many species is rapidly declining and around a quarter of the world’s sharks and rays are threatened with extinction. At a regional scale this negative trend has also been evidenced in the central Mediterranean Sea, where bottom-trawl fisheries have affected the biomass of certain rays (e.g. Raja clavata) and sharks (e.g. Mustelus spp.). Detailed knowledge of elasmobranch habitat requirements is essential for biodiversity conservation and fisheries management, but this is often hampered by a poor understanding of their spatial ecology. Habitat suitability models were used to investigate the habitat preference of nine elasmobranch species and their overall diversity (number of species) in relation to five environmental predictors (i.e. depth, sea surface temperature, surface salinity, slope and rugosity) in the central Mediterranean Sea. Results showed that depth, seafloor morphology and sea surface temperature were the main drivers for elasmobranch habitat suitability. Predictive distribution maps revealed different species-specific patterns of suitable habitat while high assemblage diversity was predicted in deeper offshore waters (400–800 m depth). This study helps to identify priority conservation areas and diversity hot-spots for rare and endangered elasmobranchs in the Mediterranean Sea

Genetic architecture distinguishes systemic juvenile idiopathic arthritis from other forms of juvenile idiopathic arthritis: clinical and therapeutic implications

OBJECTIVES: Juvenile idiopathic arthritis (JIA) is a heterogeneous group of conditions unified by the presence of chronic childhood arthritis without an identifiable cause. Systemic JIA (sJIA) is a rare form of JIA characterised by systemic inflammation. sJIA is distinguished from other forms of JIA by unique clinical features and treatment responses that are similar to autoinflammatory diseases. However, approximately half of children with sJIA develop destructive, long-standing arthritis that appears similar to other forms of JIA. Using genomic approaches, we sought to gain novel insights into the pathophysiology of sJIA and its relationship with other forms of JIA. METHODS: We performed a genome-wide association study of 770 children with sJIA collected in nine countries by the International Childhood Arthritis Genetics Consortium. Single nucleotide polymorphisms were tested for association with sJIA. Weighted genetic risk scores were used to compare the genetic architecture of sJIA with other JIA subtypes. RESULTS: The major histocompatibility complex locus and a locus on chromosome 1 each showed association with sJIA exceeding the threshold for genome-wide significance, while 23 other novel loci were suggestive of association with sJIA. Using a combination of genetic and statistical approaches, we found no evidence of shared genetic architecture between sJIA and other common JIA subtypes. CONCLUSIONS: The lack of shared genetic risk factors between sJIA and other JIA subtypes supports the hypothesis that sJIA is a unique disease process and argues for a different classification framework. Research to improve sJIA therapy should target its unique genetics and specific pathophysiological pathways

New routes to the functionalization patterning and manufacture of graphene-based materials for biomedical applications

This is the author accepted manuscript. The final version is available from Royal Society via the DOI in this record.Graphene-based materials are being widely explored for a range of biomedical applications, from targeted drug delivery to biosensing, bioimaging and use for antibacterial treatments, to name but a few. In many such applications it is not graphene itself that is used as the active agent, but one of its chemically-functionalised forms. The type of chemical species used for functionalisation will play a key role in determining the utility of any graphene-based device in any particular biomedical application, since this determines to a large part its physical, chemical, electrical and optical interactions. However, other factors will also be important in determining the eventual uptake of graphene-based biomedical technologies, in particular the ease and cost of manufacture of proposed device and system designs. In this work we describe three novel routes for the chemical functionalisation of graphene using oxygen, iron chloride and fluorine. We also introduce novel in-situ methods for controlling and patterning such functionalisation on the micro- and nano-scales. Our approaches are readily transferable to large-scale manufacturing, potentially paving the way for the eventual cost-effective production of functionalised graphene-based materials, devices and systems for a range of important biomedical applications.AA, VKN, MFC and CDW acknowledge funding via the EU FP7 project CareRAMM (grant no. 309980). SR and MFC. acknowledge financial support from the Engineering and Physical Sciences Research Council (grant nos. EP/J000396/1, EP/K017160/1, EP/K010050/1, EP/G036101/1, EP/M001024/1, and EP/M002438/1)

The evolutionary dynamics of microRNAs in domestic mammals

MiRNAs are crucial regulators of gene expression found across both the plant and animal kingdoms. While the number of annotated miRNAs deposited in miRBase has greatly increased in recent years, few studies provided comparative analyses across sets of related species, or investigated the role of miRNAs in the evolution of gene regulation. We generated small RNA libraries across 5 mammalian species (cow, dog, horse, pig and rabbit) from 4 different tissues (brain, heart, kidney and testis). We identified 1676 miRBase and 413 novel miRNAs by manually curating the set of computational predictions obtained from miRCat and miRDeep2. Our dataset spanning five species has enabled us to investigate the molecular mechanisms and selective pressures driving the evolution of miRNAs in mammals. We highlight the important contributions of intronic sequences (366 orthogroups), duplication events (135 orthogroups) and repetitive elements (37 orthogroups) in the emergence of new miRNA loci. We use this framework to estimate the patterns of gains and losses across the phylogeny, and observe high levels of miRNA turnover. Additionally, the identification of lineage-specific losses enables the characterisation of the selective constraints acting on the associated target sites. Compared to the miRBase subset, novel miRNAs tend to be more tissue specific. 20 percent of novel orthogroups are restricted to the brain, and their target repertoires appear to be enriched for neuron activity and differentiation processes. These findings may reflect an important role for young miRNAs in the evolution of brain expression plasticity. Many seed sequences appear to be specific to either the cow or the dog. Analyses on the associated targets highlight the presence of several genes under artificial positive selection, suggesting an involvement of these miRNAs in the domestication process. Altogether, we provide an overview on the evolutionary mechanisms responsible for miRNA turnover in 5 domestic species, and their possible contribution to the evolution of gene regulation