Signatures of magnetic separatrices at the borders of a crater flux transfer event connected to an active X‐line

In this paper, we present Magnetospheric Multiscale (MMS) observations of a flux transfer event (FTE) characterized by a clear signature in the magnetic field magnitude, which shows maximum at the center flanked by two depressions, detected during a period of stable southward interplanetary magnetic field. This class of FTEs are called “crater‐FTEs” and have been suggested to be connected with active reconnection X line. The MMS burst mode data allow the identification of intense fluctuations in the components of the electric field and electron velocity parallel to the magnetic field at the borders of the FTE, which are interpreted as signatures of the magnetic separatrices. In particular, the strong and persistent fluctuations of the parallel electron velocity at the borders of this crater‐FTE reported for the first time in this paper, sustain the field‐aligned current part of the Hall current system along the separatrix layer, and confirm that this FTE is connected with an active reconnection X line. Our observations suggest a stratification of particles inside the reconnection layer, where electrons are flowing toward the X line along the separatrix, are flowing away from the X line along the reconnected field lines adjacent to the separatrices, and more internally ions and electrons are flowing away from the X line with comparable velocities, forming the reconnection jets. This stratification of the reconnection layer forming the FTE, together with the reconnection jet at the trailing edge of the FTE, suggests clearly that this FTE is formed by the single X line generation mechanism

Cluster and MMS simultaneous observations of magnetosheath high speed jets and their impact on the magnetopause

When the supersonic solar wind encounters the Earth's magnetosphere a shock, called bow shock, is formed and the plasma is decelerated and thermalized in the magnetosheath downstream from the shock. Sometimes, however, due to discontinuities in the solar wind, bow shock ripples or ionized dust clouds carried by the solar wind, high speed jets (HSJs) are observed in the magnetosheath. These HSJs have typically a Vx component larger than 200 km s−1 and their dynamic pressure can be a few times the solar wind dynamic pressure. They are typically observed downstream from the quasi-parallel bow shock and have a typical size around one Earth radius (RE) in XGSE. We use a conjunction of Cluster and MMS, crossing simultaneously the magnetopause, to study the characteristics of these HSJs and their impact on the magnetopause. Over 1 h 15 min interval in the magnetosheath, Cluster observed 21 HSJs. During the same period, MMS observed 12 HSJs and entered the magnetosphere several times. A jet was observed simultaneously by both MMS and Cluster and it is very likely that they were two distinct HSJs. This shows that HSJs are not localized into small regions but could span a region larger than 10 RE, especially when the quasi-parallel shock is covering the entire dayside magnetosphere under radial IMF. During this period, two and six magnetopause crossings were observed, respectively, on Cluster and MMS with a significant angle between the observation and the expected normal deduced from models. The angles observed range between from 11° up to 114°. One inbound magnetopause crossing observed by Cluster (magnetopause moving out at 142 km s−1) was observed simultaneous to an outbound magnetopause crossing observed by MMS (magnetopause moving in at −83 km s−1), showing that the magnetopause can have multiple local indentation places, most likely independent from each other. Under the continuous impacts of HSJs, the magnetopause is deformed significantly and can even move in opposite directions at different places. It can therefore not be considered as a smooth surface anymore but more as surface full of local indents. Four dust impacts were observed on MMS, although not at the time when HSJs are observed, showing that dust clouds would have been present during the observations. No dust cloud in the form of Interplanetary Field Enhancements was however observed in the solar wind which may exclude large clouds of dust as a cause of HSJs. Radial IMF and Alfvén Mach number above 10 would fulfill the criteria for the creation of bow shock ripples and the subsequent crossing of HSJs in the magnetosheath.publishedVersio

Metarhizium anisopliae Pathogenesis of Mosquito Larvae: A Verdict of Accidental Death

Metarhizium anisopliae, a fungal pathogen of terrestrial arthropods, kills the aquatic larvae of Aedes aegypti, the vector of dengue and yellow fever. The fungus kills without adhering to the host cuticle. Ingested conidia also fail to germinate and are expelled in fecal pellets. This study investigates the mechanism by which this fungus adapted to terrestrial hosts kills aquatic mosquito larvae. Genes associated with the M. anisopliae early pathogenic response (proteinases Pr1 and Pr2, and adhesins, Mad1 and Mad2) are upregulated in the presence of larvae, but the established infection process observed in terrestrial hosts does not progress and insecticidal destruxins were not detected. Protease inhibitors reduce larval mortality indicating the importance of proteases in the host interaction. The Ae. aegypti immune response to M. anisopliae appears limited, whilst the oxidative stress response gene encoding for thiol peroxidase is upregulated. Cecropin and Hsp70 genes are downregulated as larval death occurs, and insect mortality appears to be linked to autolysis through caspase activity regulated by Hsp70 and inhibited, in infected larvae, by protease inhibitors. Evidence is presented that a traditional host-pathogen response does not occur as the species have not evolved to interact. M. anisopliae retains pre-formed pathogenic determinants which mediate host mortality, but unlike true aquatic fungal pathogens, does not recognise and colonise the larval host

Meta-analysis indicates that common variants at the DISC1 locus are not associated with schizophrenia

Several polymorphisms in the Disrupted-in-Schizophrenia-1 (DISC1) gene are reported to be associated with schizophrenia. However, to date, there has been little effort to evaluate the evidence for association systematically. We carried out an imputation-driven meta-analysis, the most comprehensive to date, using data collected from 10 candidate gene studies and three genome-wide association studies containing a total of 11 626 cases and 15 237 controls. We tested 1241 single-nucleotide polymorphisms in total, and estimated that our power to detect an effect from a variant with minor allele frequency >5% was 99% for an odds ratio of 1.5 and 51% for an odds ratio of 1.1. We find no evidence that common variants at the DISC1 locus are associated with schizophrenia

Characterisation and Carriage Ratio of Clostridium difficile Strains Isolated from a Community-Dwelling Elderly Population in the United Kingdom

Background Community-associated Clostridium difficile infection (CDI) appears to be an increasing problem. Reported carriage rates by C.difficile are debatable with suggestions that primary asymptomatic carriage is associated with decreased risk of subsequent diarrhoea. However, knowledge of potential reservoirs and intestinal carriage rates in the community, particularly in the elderly, the most susceptible group, is limited. We have determined the presence of C.difficile in the faeces of a healthy elderly cohort living outside of long-term care facilities (LCFs) in the United Kingdom. Methods Faecal samples from 149 community-based healthy elderly volunteers (median age 81 years) were screened for C.difficile using direct (Brazier's CCEY) and enrichment (Cooked Meat broth) culture methods and a glutamate dehydrogenase (GDH) immunoassay. Isolates were PCR-ribotyped and analysed for toxin production and the presence of toxin genes. Results Of 149 faecal samples submitted, six (4%) were found to contain C.difficile. One particular sample was positive by both the GDH immunoassay and direct culture, and concurrently produced two distinct strain types: one toxigenic and the other non-toxigenic. The other five samples were only positive by enrichment culture method. Overall, four C.difficile isolates were non-toxigenic (PCR-ribotypes 009, 026 (n = 2) and 039), while three were toxigenic (PCR-ribotypes 003, 005 and 106). All individuals who had a positive culture were symptom-free and none of them had a history of CDI and/or antibiotics use in the 3 month period preceding recruitment. Conclusions To our knowledge, this is the first study of the presence of C.difficile in healthy elderly community-dwelling individuals residing outside of LCFs. The observed carriage rate is lower than that reported for individuals in LCFs and interestingly no individual carried the common epidemic strain PCR-ribotype 027 (NAP1/BI). Further follow-up of asymptomatic carriers in the community, is required to evaluate host susceptibility to CDI and identify dynamic changes in the host and microbial environment that are associated with pathogenicity

Volcanic impacts on the Holocene vegetation history of Britain and Ireland? A review and meta-analysis of the pollen evidence

Volcanic ash layers show that the products of Icelandic volcanism reached Britain and Ireland many times during the Holocene. Historical records suggest that at least one eruption, that of Laki in a.d. 1783, was associated with impacts on vegetation. These results raise the question: did Icelandic volcanism affect the Holocene vegetation history of Britain and Ireland? Several studies have used pollen data to address this issue but no clear consensus has been reached. We re-analyse the palynological data using constrained ordination with various representations of potential volcanic impacts. We find that the palynological evidence for volcanic impacts on vegetation is weak but suggest that this is a case of absence of evidence and is not necessarily evidence of absence of impact. To increase the chances of identifying volcanic impacts, future studies need to maximise temporal resolution, replicate results, and investigate a greater number of tephras in a broader range of locations, including more studies from lake sediments

Electron-scale measurements of magnetic reconnection in space

Magnetic reconnection is a fundamental physical process in plasmas whereby stored magnetic energy is converted into heat and kinetic energy of charged particles. Reconnection occurs in many astrophysical plasma environments and in laboratory plasmas. Using very high time resolution measurements, NASA’s Magnetospheric Multiscale Mission (MMS) has found direct evidence for electron demagnetization and acceleration at sites along the sunward boundary of Earth’s magnetosphere where the interplanetary magnetic field reconnects with the terrestrial magnetic field. We have (i) observed the conversion of magnetic energy to particle energy, (ii) measured the electric field and current, which together cause the dissipation of magnetic energy, and (iii) identified the electron population that carries the current as a result of demagnetization and acceleration within the reconnection diffusion/dissipation region

What 'outliers' tell us about missed opportunities for tuberculosis control: a cross-sectional study of patients in Mumbai, India

BACKGROUND: India's Revised National Tuberculosis Control Programme (RNTCP) is deemed highly successful in terms of detection and cure rates. However, some patients experience delays in accessing diagnosis and treatment. Patients falling between the 96th and 100th percentiles for these access indicators are often ignored as atypical 'outliers' when assessing programme performance. They may, however, provide clues to understanding why some patients never reach the programme. This paper examines the underlying vulnerabilities of patients with extreme values for delays in accessing the RNTCP in Mumbai city, India. METHODS: We conducted a cross-sectional study with 266 new sputum positive patients registered with the RNTCP in Mumbai. Patients were classified as 'outliers' if patient, provider and system delays were beyond the 95th percentile for the respective variable. Case profiles of 'outliers' for patient, provider and system delays were examined and compared with the rest of the sample to identify key factors responsible for delays. RESULTS: Forty-two patients were 'outliers' on one or more of the delay variables. All 'outliers' had a significantly lower per capita income than the remaining sample. The lack of economic resources was compounded by social, structural and environmental vulnerabilities. Longer patient delays were related to patients' perception of symptoms as non-serious. Provider delays were incurred as a result of private providers' failure to respond to tuberculosis in a timely manner. Diagnostic and treatment delays were minimal, however, analysis of the 'outliers' revealed the importance of social support in enabling access to the programme. CONCLUSION: A proxy for those who fail to reach the programme, these case profiles highlight unique vulnerabilities that need innovative approaches by the RNTCP. The focus on 'outliers' provides a less resource- and time-intensive alternative to community-based studies for understanding the barriers to reaching public health programmes

Loss of STOP Protein Impairs Peripheral Olfactory Neurogenesis

International audienceIn conclusion, STOP protein seems to be involved in the establishment of synapses in the olfactory glomerulus. Our results indicate that the olfactory system of STOP null mice is a well-suited experimental model (1) for the study of the mechanism of action of STOP protein in synaptic function/plasticity and (2) for pathophysiological studies of the mechanisms of altered neuronal connections in schizophrenia

Metarhizium brunneum Blastospore Pathogenesis in Aedes aegypti Larvae: Attack on Several Fronts Accelerates Mortality

Aedes aegypti is the vector of a wide range of diseases (e.g. yellow fever, dengue, Chikungunya and Zika) which impact on over half the world's population. Entomopathogenic fungi such as Metarhizium anisopliae and Beauveria bassiana have been found to be highly efficacious in killing mosquito larvae but only now are the underlying mechanisms for pathogenesis being elucidated. Recently it was shown that conidia of M. anisopliae caused stress induced mortality in Ae. aegypti larvae, a different mode of pathogenicity to that normally seen in terrestrial hosts. Blastospores constitute a different form of inoculum produced by this fungus when cultured in liquid media and although blastospores are generally considered to be more virulent than conidia no evidence has been presented to explain why. In our study, using a range of biochemical, molecular and microscopy methods, the infection process of Metarhizium brunneum (formerly M. anisopliae) ARSEF 4556 blastospores was investigated. It appears that the blastospores, unlike conidia, readily adhere to and penetrate mosquito larval cuticle. The blastospores are readily ingested by the larvae but unlike the conidia are able infect the insect through the gut and rapidly invade the haemocoel. The fact that pathogenicity related genes were upregulated in blastospores exposed to larvae prior to invasion, suggests the fungus was detecting host derived cues. Similarly, immune and defence genes were upregulated in the host prior to infection suggesting mosquitoes were also able to detect pathogen-derived cues. The hydrophilic blastospores produce copious mucilage, which probably facilitates adhesion to the host but do not appear to depend on production of Pr1, a cuticle degrading subtilisin protease, for penetration since protease inhibitors did not significantly alter blastospore virulence. The fact the blastospores have multiple routes of entry (cuticle and gut) may explain why this form of the inoculum killed Ae. aegypti larvae in a relatively short time (12-24hrs), significantly quicker than when larvae were exposed to conidia. This study shows that selecting the appropriate form of inoculum is important for efficacious control of disease vectors such as Ae. aegypti