Magnetism and its microscopic origin in iron-based high-temperature superconductors

High-temperature superconductivity in the iron-based materials emerges from, or sometimes coexists with, their metallic or insulating parent compound states. This is surprising since these undoped states display dramatically different antiferromagnetic (AF) spin arrangements and N$\rm \acute{e}$el temperatures. Although there is general consensus that magnetic interactions are important for superconductivity, much is still unknown concerning the microscopic origin of the magnetic states. In this review, progress in this area is summarized, focusing on recent experimental and theoretical results and discussing their microscopic implications. It is concluded that the parent compounds are in a state that is more complex than implied by a simple Fermi surface nesting scenario, and a dual description including both itinerant and localized degrees of freedom is needed to properly describe these fascinating materials.Comment: 14 pages, 4 figures, Review article, accepted for publication in Nature Physic

Malaria vector research and control in Haiti: a systematic review

BACKGROUND: Haiti has a set a target of eliminating malaria by 2020. However, information on malaria vector research in Haiti is not well known. This paper presents results from a systematic review of the literature on malaria vector research, bionomics and control in Haiti. METHODS: A systematic search of literature published in French, Spanish and English languages was conducted in 2015 using Pubmed (MEDLINE), Google Scholar, EMBASE, JSTOR WHOLIS and Web of Science databases as well other grey literature sources such as USAID, and PAHO. The following search terms were used: malaria, Haiti, Anopheles, and vector control. RESULTS: A total of 132 references were identified with 40 high quality references deemed relevant and included in this review. Six references dealt with mosquito distribution, seven with larval mosquito ecology, 16 with adult mosquito ecology, three with entomological indicators of malaria transmission, eight with insecticide resistance, one with sero-epidemiology and 16 with vector control. In the last 15 years (2000–2015), there have only been four published papers and three-scientific meeting abstracts on entomology for malaria in Haiti. Overall, the general literature on malaria vector research in Haiti is limited and dated. DISCUSSION: Entomological information generated from past studies in Haiti will contribute to the development of strategies to achieve malaria elimination on Hispaniola. However it is of paramount importance that malaria vector research in Haiti is updated to inform decision-making for vector control strategies in support of malaria elimination

Systematic Identification of Genes that Regulate Neuronal Wiring in the Drosophila Visual System

Forward genetic screens in model organisms are an attractive means to identify those genes involved in any complex biological process, including neural circuit assembly. Although mutagenesis screens are readily performed to saturation, gene identification rarely is, being limited by the considerable effort generally required for positional cloning. Here, we apply a systematic positional cloning strategy to identify many of the genes required for neuronal wiring in the Drosophila visual system. From a large-scale forward genetic screen selecting for visual system wiring defects with a normal retinal pattern, we recovered 122 mutations in 42 genetic loci. For 6 of these loci, the underlying genetic lesions were previously identified using traditional methods. Using SNP-based mapping approaches, we have now identified 30 additional genes. Neuronal phenotypes have not previously been reported for 20 of these genes, and no mutant phenotype has been previously described for 5 genes. The genes encode a variety of proteins implicated in cellular processes such as gene regulation, cytoskeletal dynamics, axonal transport, and cell signalling. We conducted a comprehensive phenotypic analysis of 35 genes, scoring wiring defects according to 33 criteria. This work demonstrates the feasibility of combining large-scale gene identification with large-scale mutagenesis in Drosophila, and provides a comprehensive overview of the molecular mechanisms that regulate visual system wiring

Social cohesion, mental wellbeing and health-related quality of life among a cohort of social housing residents in Cornwall: a cross sectional study

Background: Research and policy have identified social cohesion as a potentially modifiable determinant of health and wellbeing that could contribute to more sustainable development. However, the function of social cohesion appears to vary between communities. The aim of this study was to analyse the levels of, and associations, between social cohesion, mental wellbeing, and physical and mental health-related quality of life among a cohort of social housing residents from low socioeconomic status communities in Cornwall, UK. Social housing is below market-rate rental accommodation made available to those in certain health or economic circumstances. These circumstances may impact on the form and function of social cohesion. Methods: During recruitment, participants in the Smartline project completed the Short Warwick-Edinburgh Mental Wellbeing Scale, SF-12v2 and an eight item social cohesion scale. Cross sectional regression analyses of these data adjusted for gender, age, national identity, area socioeconomic status, rurality, education, employment, and household size were undertaken to address the study aim. Results: Complete data were available from 305 (92.7%) participants in the Smartline project. Univariable analyses identified a significant association between social cohesion, mental wellbeing and mental health-related quality of life. Within fully adjusted multivariable models, social cohesion only remained significantly associated with mental wellbeing. Sensitivity analyses additionally adjusting for ethnicity and duration of residence, where there was greater missing data, did not alter the findings. Conclusions: Among a relatively homogeneous cohort, the reported level of social cohesion was only found to be significantly associated with higher mental wellbeing, not physical or mental health-related quality of life. The efforts made by social housing providers to offer social opportunities to all their residents regardless of individual physical or mental health state may support the development of a certain degree of social cohesion. Sense of control or safety in communities may be more critical to health than social cohesion. Additional observational research is needed before attempts are made to alter social cohesion to improve health.This article is freely available via Open Access. Click on the Publisher URL to access it via the publisher's site.The Smartline project is receiving up to £4,188,318 of funding from the England European Regional Development Fund as part of the European Structural and Investment Funds Growth Programme 2014–2020. The Ministry of Housing, Communities and Local Government (and in London the intermediate body Greater London Authority) is the Managing Authority for European Regional Development Fund. Established by the European Union, the European Regional Development Fund helps local areas stimulate their economic development by investing in projects which will support innovation, businesses, create jobs and local community regenerations. For more information visit https://www.gov.uk/european-growth-funding. Additional funding is from the South West Academic Health Science Network. KW is supported by the National Institute for Health Research Applied Research Collaboration South West Peninsula. KMa was funded by a National Institute for Health Research (NIHR) Knowledge Mobilisation Research Fellowship and ESRC Smartline Project for this research. The views expressed in this publication are those of the author(s) and not necessarily those of the National Institute for Health Research or the Department of Health and Social Care. The funders did not contribute to the design of the study or collection, analysis, and interpretation of data or in writing the manuscript in any way.published version, accepted versio

The one dimensional Kondo lattice model at partial band filling

The Kondo lattice model introduced in 1977 describes a lattice of localized magnetic moments interacting with a sea of conduction electrons. It is one of the most important canonical models in the study of a class of rare earth compounds, called heavy fermion systems, and as such has been studied intensively by a wide variety of techniques for more than a quarter of a century. This review focuses on the one dimensional case at partial band filling, in which the number of conduction electrons is less than the number of localized moments. The theoretical understanding, based on the bosonized solution, of the conventional Kondo lattice model is presented in great detail. This review divides naturally into two parts, the first relating to the description of the formalism, and the second to its application. After an all-inclusive description of the bosonization technique, the bosonized form of the Kondo lattice hamiltonian is constructed in detail. Next the double-exchange ordering, Kondo singlet formation, the RKKY interaction and spin polaron formation are described comprehensively. An in-depth analysis of the phase diagram follows, with special emphasis on the destruction of the ferromagnetic phase by spin-flip disorder scattering, and of recent numerical results. The results are shown to hold for both antiferromagnetic and ferromagnetic Kondo lattice. The general exposition is pedagogic in tone.Comment: Review, 258 pages, 19 figure

Factors influencing the use of topical repellents: implications for the effectiveness of malaria elimination strategies

In Cambodia, despite an impressive decline in prevalence over the last 10 years, malaria is still apublic health problem in some parts of the country. This is partly due to vectors that bite earlyand outdoors reducing the effectiveness of measures such as Long-Lasting Insecticidal Nets.Repellents have been suggested as an additional control measure in such settings. As part of acluster-randomized trial on the effectiveness of topical repellents in controlling malaria infections atcommunity level, a mixed-methods study assessed user rates and determinants of use. Repellentswere made widely available and Picaridin repellent reduced 97% of mosquito bites. However,despite high acceptability, daily use was observed to be low (8%) and did not correspond to thereported use in surveys (around 70%). The levels of use aimed for by the trial were never reachedas the population used it variably across place (forest, farms and villages) and time (seasons), or inalternative applications (spraying on insects, on bed nets, etc.). These findings show the key role ofhuman behavior in the effectiveness of malaria preventive measures, questioning whether malaria inlow endemic settings can be reduced substantially by introducing measures without researching andoptimizing community involvement strategies

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta