The characterisation of mullite-related phases by hydrothermal synthesis

The aluminosilicate called mullite has been prepared by hydrothermal processing from aluminium- and silicon- acetates. The phase evolution of the products and the mechanism of formation of mullite from its precursors has been examined by x-ray powder diffraction, magic-angle spinning NMR spectroscopy, FTIR spectroscopy and electron microscopy. The product obtained from co-processing aluminium- and silicon- acetates was found to be a biphasic material with strong interfacial interactions between pseudoboehmite and amorphous silica-gel type phases. This interfacial interaction resulted in mullite being formed after calcination at 1250°C, which is a lower temperature than would normally be expected for the formation of mullite. Lattice parameter measurements of mullite calcined up to 1400°C suggested that a metastable state may be formed at the lower temperature. The effect of adding acid to the reagent mixture was examined and found to have no effect on the chemistry of the phase evolution of the products. The synthesis of iron-doped mullite has also been examined by x-ray powder diffraction, Mössbauer spectroscopy, EXAFS and electron microscopy. The iron-containing phases in dried intermediate materials exhibited superparamagnetism. Upon calcination iron-doped mullite formed at 1150°C with an iron content up to 14 mol%. EXAFS showed the iron to occupy octahedral sites in the mullite structure.The synthesis of magnesium-aluminium spinel has been examined using a similar methodology. The interfacial interaction between the initial precursors was found to be stronger than that observed in the aluminosilicate system. This increase in interfacial interaction is associated with the lower temperature required to form spinel (400°C)

Understanding the enablers and barriers to implementing a patient-led escalation system: a qualitative study

Background: The management of acute deterioration following surgery remains highly variable. Patients and families can play an important role in identifying early signs of deterioration but effective contribution to escalation of care can be practically difficult to achieve. This paper reports the enablers and barriers to the implementation of patient-led escalation systems found during a process evaluation of a quality improvement programme Rescue for Emergency Surgery Patients Observed to uNdergo acute Deterioration (RESPOND). Methods: The research used ethnographic methods, including over 100 hours of observations on surgical units in three English hospitals in order to understand the everyday context of care. Observations focused on the coordination of activities such as handovers and how rescue featured as part of this. We also conducted 27 interviews with a range of clinical and managerial staff and patients. We employed a thematic analysis approach, combined with a theoretically focused implementation coding framework, based on Normalisation Process Theory. Results: We found that organisational infrastructural support in the form of a leadership support and clinical care outreach teams with capacity were enablers in implementing the patient-led escalation system. Barriers to implementation included making changes to professional practice without discussing the value and legitimacy of operationalising patient concerns, and ensuring equity of use. We found that organisational work is needed to overcome patient fears about disrupting social and cultural norms. Conclusions: This paper reveals the need for infrastructural support to facilitate the implementation of a patient-led escalation system, and leadership support to normalise the everyday process of involving patients and families in escalation. This type of system may not achieve its goals without properly understanding and addressing the concerns of both nurses and patients

Interactions Between Uniformly Magnetized Spheres

We use simple symmetry arguments suitable for undergraduate students to demonstrate that the magnetic energy, forces, and torques between two uniformly magnetized spheres are identical to those between two point magnetic dipoles. These arguments exploit the equivalence of the field outside of a uniformly magnetized sphere with that of a point magnetic dipole, and pertain to spheres of arbitrary sizes, positions, and magnetizations. The point dipole/sphere equivalence for magnetic interactions may be useful in teaching and research, where dipolar approximations for uniformly magnetized spheres can now be considered to be exact. The work was originally motivated by interest in the interactions between collections of small neodymium magnetic spheres used as desk toys

ALMA 1.3 Millimeter Map of the HD 95086 System

Planets and minor bodies such as asteroids, Kuiper-belt objects and comets are integral components of a planetary system. Interactions among them leave clues about the formation process of a planetary system. The signature of such interactions is most prominent through observations of its debris disk at millimeter wavelengths where emission is dominated by the population of large grains that stay close to their parent bodies. Here we present ALMA 1.3 mm observations of HD 95086, a young early-type star that hosts a directly imaged giant planet b and a massive debris disk with both asteroid- and Kuiper-belt analogs. The location of the Kuiper-belt analog is resolved for the first time. The system can be depicted as a broad ($\Delta R/R \sim$0.84), inclined (30\arcdeg$\pm$3\arcdeg) ring with millimeter emission peaked at 200$\pm$6 au from the star. The 1.3 mm disk emission is consistent with a broad disk with sharp boundaries from 106$\pm$6 to 320$\pm$20 au with a surface density distribution described by a power law with an index of --0.5$\pm$0.2. Our deep ALMA map also reveals a bright source located near the edge of the ring, whose brightness at 1.3 mm and potential spectral energy distribution are consistent with it being a luminous star-forming galaxy at high redshift. We set constraints on the orbital properties of planet b assuming co-planarity with the observed disk.Comment: accepted for publication in A

The clumpy structure of ϵ\epsilon Eridani's debris disc revisited by ALMA

$\epsilon$ Eridani is the closest star to our Sun known to host a debris disc. Prior observations in the (sub-)millimetre regime have potentially detected clumpy structure in the disc and attributed this to interactions with an (as yet) undetected planet. However, the prior observations were unable to distinguish between structure in the disc and background confusion. Here we present the first ALMA image of the entire disc, which has a resolution of 1.6"$\times$1.2". We clearly detect the star, the main belt and two point sources. The resolution and sensitivity of this data allow us to clearly distinguish background galaxies (that show up as point sources) from the disc emission. We show that the two point sources are consistent with background galaxies. After taking account of these, we find that resolved residuals are still present in the main belt, including two clumps with a $>3\sigma$ significance -- one to the east of the star and the other to the northwest. We perform $n$-body simulations to demonstrate that a migrating planet can form structures similar to those observed by trapping planetesimals in resonances. We find that the observed features can be reproduced by a migrating planet trapping planetesimals in the 2:1 mean motion resonance and the symmetry of the most prominent clumps means that the planet should have a position angle of either ${\sim10^\circ}$ or ${\sim190^\circ}$. Observations over multiple epochs are necessary to test whether the observed features rotate around the star.Comment: 16 pages, 10 figures, accepted for publication in MNRA

Identification of a Human Monoclonal Antibody to Replace Equine Diphtheria Anti-toxin for the Treatment of Diphtheria

Diphtheria anti-toxin (DAT) has been used to treat Corynebacterium diphtheriae infection for over one hundred years. While the global incidence of diphtheria has declined in the 20th century, the disease remains endemic in many parts of the world and significant outbreaks still occur. Diphtheria anti-toxin is an equine polyclonal antibody with considerable side effects that is in critically short supply globally. A safer, more readily available alternative to DAT would be desirable. In the current study, we cloned human monoclonal antibodies (HuMabs) directly from antibody secreting cells of human volunteers immunized with Td vaccine. We isolated a diverse panel of HuMabs that recognized diphtheria toxoid and recombinant protein fragments of diphtheria toxin. Forty-one unique HuMabs were expressed in 293T cells and tested for neutralization of diphtheria toxin in in vitro cytotoxicity assays. The lead candidate HuMab, 315C4 potently neutralized diphtheria toxin with an EC50 of 0.65 ng/mL. Additionally, 25 μg of 315C4 completely protected guinea pigs in an in vivo lethality model. In comparison, 1.6 IU of DAT was necessary for full protection resulting in an estimated relative potency of 64 IU/mg for 315C4. We further established that our lead candidate HuMab binds to the receptor binding domain of diphtheria toxin and blocks the toxin from binding to the putative receptor, heparin binding-epidermal growth factor like growth factor. The discovery of a specific and potent neutralizing antibody against diphtheria toxin holds promise as a potential human therapeutic and is being developed for human use

The REASONS Survey : resolved millimeter observations of a large debris disk around the nearby F Star HD 170773

Debris disks are extrasolar analogs to our own Kuiper Belt and they are detected around at least 17% of nearby Sun-like stars. The morphology and dynamics of a disk encode information about its history, as well as that of any exoplanets within the system. We used the Atacama Large Millimeter/submillimeter Array (ALMA) to obtain 1.3 mm observations of the debris disk around the nearby F5V star HD 170773. We image the face-on ring and determine its fundamental parameters by forward-modeling the interferometric visibilities through a Markov Chain Monte Carlo approach. Using a symmetric Gaussian surface density profile, we find a 71 ± 4 au wide belt with a radius of {193}-3+2 au, a relatively large radius compared with most other millimeter-resolved belts around late A/early F type stars. This makes HD 170773 part of a group of four disks around A and F stars with radii larger than expected from the recently reported planetesimal belt radius—stellar luminosity relation. Two of these systems are known to host directly imaged giant planets, which may point to a connection between large belts and the presence of long-period giant planets. We also set upper limits on the presence of CO and CN gas in the system, which imply that the exocomets that constitute this belt have CO and HCN ice mass fractions of <77% and <3%, respectively. This is consistent with solar system comets and other exocometary belts

Association mapping of diastatic power in UK winter and spring barley by exome sequencing of phenotypically contrasting variety sets

Diastatic Power (DP) is an important quality trait for malt used in adjunct brewing and distilling. Substantial genetic variation for DP exists within UK elite barley cultivars, but breeding progress has been slow due to the limited demand, compared to the overall barley market, and difficulties in assessing DP. Estimates of DP (taken from recommended and national list trials between 1994 and 2012) from a collection of UK elite winter and spring varieties were used to identify contrasting sets of high and low DP varieties. DNA samples were pooled within sets and exome capture sequencing performed. Allele frequency estimates of Single Nucleotide Polymorphisms (SNPs) identified from the sequencing were used to identify genomic locations associated with differences in DP. Individual genotypes were generated from a set of custom KASP assays, both within sets and in a wider germplasm collection, to validate allele frequency estimates and marker associations with DP. QTL identified regions previously linked to variation in DP as well as novel associations. QTL colocalised with a number of genes annotated as having a diastase related function. Results indicate that winter barley is more genetically diverse for genes influencing DP. The marker assays produced by this work represent a resource that is available for immediate use by barley breeders in the production of new high DP varieties.Publisher PDFPeer reviewe

Genetic risk and a primary role for cell-mediated immune mechanisms in multiple sclerosis.

Multiple sclerosis is a common disease of the central nervous system in which the interplay between inflammatory and neurodegenerative processes typically results in intermittent neurological disturbance followed by progressive accumulation of disability. Epidemiological studies have shown that genetic factors are primarily responsible for the substantially increased frequency of the disease seen in the relatives of affected individuals, and systematic attempts to identify linkage in multiplex families have confirmed that variation within the major histocompatibility complex (MHC) exerts the greatest individual effect on risk. Modestly powered genome-wide association studies (GWAS) have enabled more than 20 additional risk loci to be identified and have shown that multiple variants exerting modest individual effects have a key role in disease susceptibility. Most of the genetic architecture underlying susceptibility to the disease remains to be defined and is anticipated to require the analysis of sample sizes that are beyond the numbers currently available to individual research groups. In a collaborative GWAS involving 9,772 cases of European descent collected by 23 research groups working in 15 different countries, we have replicated almost all of the previously suggested associations and identified at least a further 29 novel susceptibility loci. Within the MHC we have refined the identity of the HLA-DRB1 risk alleles and confirmed that variation in the HLA-A gene underlies the independent protective effect attributable to the class I region. Immunologically relevant genes are significantly overrepresented among those mapping close to the identified loci and particularly implicate T-helper-cell differentiation in the pathogenesis of multiple sclerosis

The Case for Probe-class NASA Astrophysics Missions

Astrophysics spans an enormous range of questions on scales from individual planets to the entire cosmos. To address the richness of 21st century astrophysics requires a corresponding richness of telescopes spanning all bands and all messengers. Much scientific benefit comes from having the multi-wavelength capability available at the same time. Most of these bands,or measurement sensitivities, require space-based missions. Historically, NASA has addressed this need for breadth with a small number of flagship-class missions and a larger number of Explorer missions. While the Explorer program continues to flourish, there is a large gap between Explorers and strategic missions. A fortunate combination of new astrophysics technologies with new, high capacity, low dollar-per-kg to orbit launchers, and new satellite buses allow for cheaper missions with capabilities approaching strategic mission levels. NASA has recognized these developments by calling for Probe-class mission ideas for mission studies, spanning most of the electromagnetic spectrum from GeV gamma-rays to the far infrared, and the new messengers of neutrinos and ultra-high energy cosmic rays. The key insight from the Probes exercise is that order-of-magnitude advances in science performance metrics are possible across the board for initial total cost estimates in the range 500M-1B dollars