572 research outputs found
Subgrade equilibrium water content and resilient modulus for UK clays
The main functional requirement of the subgrade is to resist excessive
deformations during construction and in service. Deformation is controlled by ensuring
adequate foundation resilient modulus. UK pavement design currently relies upon the
determination of long-term CBR values for subgrades, which results in conservative
pavement foundation design. To allow more realistic design an analytical approach is
required, including measured values of resilient modulus at anticipated short- and long-term
equilibrium subgrade water contents. Resilient modulus is determined from repeated load
triaxial tests with on-sample strain measurement. Results from these tests on samples
adjusted to model the subgrade behaviour at various design conditions are presented.
These results are discussed, highlighting problems both with measuring small strains on
undisturbed soils and in predicting and modelling accurately long-term soil behaviour.
RÉSUMÉ: Le critère principal d’une sous-couche est de résister à des déformations
excessives en construction puis en service. La conception des chaussées au Royaume-Uni
est actuellement basée sur la détermination de l'indice portant Californien (CBR) à longterme
des sous-couches. Pour une conception plus réaliste, il est nécessaire d'adopter une
approche prenant en compte des valeurs de module de résilience mesurées à des degrés
d'humidité de sous-couches à l'équilibre simulés à court et long-terme. Le module de
résilience est déterminé à partir d'essais répétés en charge triaxiale avec mesure des
contraintes sur l'échantillon. Dans cet article les résultats de ces tests sur des échantillons
simulant le comportement de la sous-couche sous diverses conditions de conception sont
présentés. Ces résultats sont discutés, en soulignant les problèmes résultant de la mesure
de faibles contraintes sur des sols non-perturbés, et dus à la prédiction et à la modélisation
du comportement des sols à long-terme
In−situ monitoring Poly(3-hexylthiophene) nanowire formation and shape evolution in solution via small angle neutron scattering
The crystallization of poly(3-hexylthiophene) (P3HT) to form nanowires has attracted considerable interest because this process significantly increases the hole mobility when compared to amorphous P3HT, leading to improved performance in photovoltaic and other organic electronic devices. However, full characterization of the crystallization self-assembly of the polymer chains in solution has not been achieved yet, due to limited use of not destructive techniques. Here, we investigate the ageing-driven formation and evolution of regioregular (rr) P3HT nanostructures in chlorobenzene solution using small angle neutron scattering (SANS) and UV–Vis spectroscopy. We have monitored how the shape of the rr-P3HT aggregates evolves. The initial states for rr-P3HT chains are the random coils, which straighten to form rods. These subsequently π - π stack to form 2D lamellae, which further stack to create nanowires. The formation of nanowires is promoted both by the length of ageing and by low temperatures (). Temperatures above reverse the formation of nanowires. Additionally, atomic force microscopy (AFM) and grazing incidence wide angle x-ray scattering (GIWAXS) reveal that the nanowires can be successfully aligned during deposition by off-axis spin coating. Finally, the anisotropic conductivity of the aligned rr-P3HT nanowire films is reported. This is significant for applications such as gas sensing or organic thin film transistors, where increased conductivity and controlled nanostructure are desirable
Measuring the 3D Clustering of Undetected Galaxies Through Cross Correlation of their Cumulative Flux Fluctuations from Multiple Spectral Lines
We discuss a method for detecting the emission from high redshift galaxies by
cross correlating flux fluctuations from multiple spectral lines. If one can
fit and subtract away the continuum emission with a smooth function of
frequency, the remaining signal contains fluctuations of flux with frequency
and angle from line emitting galaxies. Over a particular small range of
observed frequencies, these fluctuations will originate from sources
corresponding to a series of different redshifts, one for each emission line.
It is possible to statistically isolate the fluctuations at a particular
redshift by cross correlating emission originating from the same redshift, but
in different emission lines. This technique will allow detection of clustering
fluctuations from the faintest galaxies which individually cannot be detected,
but which contribute substantially to the total signal due to their large
numbers. We describe these fluctuations quantitatively through the line cross
power spectrum. As an example of a particular application of this technique, we
calculate the signal-to-noise ratio for a measurement of the cross power
spectrum of the OI(63 micron) and OIII(52 micron) fine structure lines with the
proposed Space Infrared Telescope for Cosmology and Astrophysics. We find that
the cross power spectrum can be measured beyond a redshift of z=8. Such
observations could constrain the evolution of the metallicity, bias, and duty
cycle of faint galaxies at high redshifts and may also be sensitive to the
reionization history through its effect on the minimum mass of galaxies. As
another example, we consider the cross power spectrum of CO line emission
measured with a large ground based telescope like CCAT and 21-cm radiation
originating from hydrogen in galaxies after reionization with an interferometer
similar in scale to MWA, but optimized for post-reionization redshifts.Comment: 21 pages, 6 figures; Replaced with version accepted by JCAP; Added an
example of cross correlating CO line emission and 21cm line emission from
galaxies after reionizatio
Disease trajectories, place and mode of death in people with head and neck cancer: findings from the ‘Head and Neck 5000’ population-based prospective clinical cohort study
Background: Few large studies describe initial disease trajectories and subsequent mortality in people with head and neck cancer. This is a necessary first step to identify the need for palliative care and associated services.
Aim: To analyse data from the Head and Neck 5000 study to present mortality, place and mode of death within 12 months of diagnosis.
Design: Prospective cohort study.
Participants: In total, 5402 people with a new diagnosis of head and neck cancer were recruited from 76 cancer centres in the United Kingdom between April 2011 and December 2014.
Results: Initially, 161/5402 (3%) and 5241/5402 (97%) of participants were treated with ‘non-curative’ and ‘curative’ intent respectively. Within 12 months, 109/161 (68%) in the ‘non-curative’ group died compared with 482/5241 (9%) in the ‘curative’ group. Catastrophic bleed was the terminal event for 10.4% and 9.8% of people in ‘non-curative’ and ‘curative’ groups respectively; terminal airway obstruction was recorded for 7.5% and 6.3% of people in the same corresponding groups. Similar proportions of people in both groups died in a hospice (22.9% ‘non-curative’; 23.5% ‘curative’) and 45.7% of the ‘curative’ group died in hospital.
Conclusions: In addition to those with incurable head and neck cancer, there is a small but significant ‘curative’ subgroup of people who may have palliative needs shortly following diagnosis. Given the high mortality, risk of acute catastrophic event and frequent hospital death, clarifying the level and timing of palliative care services engagement would help provide assurance as to whether palliative care needs are being met
Investigation of conduction band structure, electron scattering mechanisms and phase transitions in indium selenide by means of transport measurements under pressure
In this work we report on Hall effect, resistivity and thermopower
measurements in n-type indium selenide at room temperature under either
hydrostatic and quasi-hydrostatic pressure. Up to 40 kbar (= 4 GPa), the
decrease of carrier concentration as the pressure increases is explained
through the existence of a subsidiary minimum in the conduction band. This
minimum shifts towards lower energies under pressure, with a pressure
coefficient of about -105 meV/GPa, and its related impurity level traps
electrons as it reaches the band gap and approaches the Fermi level. The
pressure value at which the electron trapping starts is shown to depend on the
electron concentration at ambient pressure and the dimensionality of the
electron gas. At low pressures the electron mobility increases under pressure
for both 3D and 2D electrons, the increase rate being higher for 2D electrons,
which is shown to be coherent with previous scattering mechanisms models. The
phase transition from the semiconductor layered phase to the metallic sodium
cloride phase is observed as a drop in resistivity around 105 kbar, but above
40 kbar a sharp nonreversible increase of the carrier concentration is
observed, which is attributed to the formation of donor defects as precursors
of the phase transition.Comment: 18 pages, Latex, 10 postscript figure
Updated guidelines for gene nomenclature in wheat
The last decade has seen a proliferation in genomic resources for wheat, including reference- and pan-genome assemblies with gene annotations, which provide new opportunities to detect, characterise, and describe genes that influence traits of interest. The expansion of genetic information has supported growth of the wheat research community and catalysed strong interest in the genes that control agronomically important traits, such as yield, pathogen resistance, grain quality, and abiotic stress tolerance. To accommodate these developments, we present an updated set of guidelines for gene nomenclature in wheat. These guidelines can be used to describe loci identified based on morphological or phenotypic features or to name genes based on sequence information, such as similarity to genes characterised in other species or the biochemical properties of the encoded protein. The updated guidelines provide a flexible system that is not overly prescriptive but provides structure and a common framework for naming genes in wheat, which may be extended to related cereal species. We propose these guidelines be used henceforth by the wheat research community to facilitate integration of data from independent studies and allow broader and more efficient use of text and data mining approaches, which will ultimately help further accelerate wheat research and breeding.EEA PergaminoFil: Boden, S. A. University of Adelaide. Waite Research Institute. School of Agriculture, Food and Wine; AustraliaFil: McIntosh, R .A. University of Sydney. School of Life and Environmental Sciences. Plant Breeding Institute; AustraliaFil: Uauy, C. Norwich Research Park. John Innes Centre; Reino UnidoFil: Krattinger, S. G. King Abdullah University of Science and Technology. Biological and Environmental Science and Engineering Division. Plant Science Program; Arabia SauditaFil: Krattinger, S. G. The Wheat Initiative; AlemaniaFil: Dubcovsky, J. University of California. Department of Plant Science; Estados UnidosFil: Dubcovsky, J. The Wheat Initiative; AlemaniaFil: Rogers, W.J. Universidad Nacional del Centro de La Provincia de Buenos Aires. Facultad de AgronomÃa (CIISAS, CIC-BIOLAB AZUL, CONICET-INBIOTEC, CRESCA). Departamento de BiologÃa Aplicada; ArgentinaFil: Rogers, W.J. The Wheat Initiative; AlemaniaFIL: Xia, X. C. Chinese Academy of Agricultural Sciences. National Wheat Improvement Centre. Institute of Crop Science; ChinaFil: Badaeva, E. D. Russian Academy of Sciences. N.I. Vavilov Institute of General Genetics; RusiaFil: Bentley, A. R. International Maize and Wheat Improvement Center (CIMMYT); MéxicoFil: Bentley, A. R. The Wheat Initiative; AlemaniaFil: Brown-Guedira, G. North Carolina State University. USDA-ARS Plant Science Research; Estados UnidosFil: Brown-Guedira, G. The Wheat Initiative; AlemaniaFil: González, Fernanda G. Instituto Nacional de TecnologÃa Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Sección EcofisiologÃa; ArgentinaFil: González, Fernanda G. Centro de Investigaciones y Transferencia del Noroeste de la Provincia de Buenos Aires (CITNOBA, CONICET-UNNOBA-UNSADA); ArgentinaFil: González, Fernanda G. The Wheat Initiative; AlemaniaFil: Zhang, Y. Fudan University. School of Life Sciences. Institute of Plant Biology. Collaborative Innovation Center of Genetics and Development. State Key Laboratory of Genetic Engineering; Chin
Active site maturation and activity of the copper-radical oxidase GlxA is governed by a tryptophan residue
GlxA from Streptomyces lividans is a mononuclear copper-radical oxidase and a member of the auxiliary activity family 5 (AA5). Its domain organisation and low sequence homology make it a distinct member of the AA5 family in which the fungal galactose 6-oxidase (Gox) is the best-characterized. GlxA is a key cuproenzyme in the copper-dependent morphological development of S. lividans with a function that is linked to the processing of an extracytoplasmic glycan. The catalytic site in GlxA and Gox contain two distinct one-electron acceptors comprising the copper ion and a 3'-(S-cysteinyl) tyrosine. The latter is formed post-translationally through a covalent bond between a cysteine and a copper coordinating tyrosine ligand and houses a radical. In GlxA and Gox a second coordination sphere tryptophan residue (Trp288 in GlxA) is present, but the orientation of the indole ring differs between the two enzymes creating a marked difference in the ?-? stacking interaction of the benzyl ring with the 3'-(S-cysteinyl) tyrosine. Differences in the spectroscopic and enzymatic activity have been reported between GlxA and Gox with the indole orientation suggested as a reason. Here we report a series of in vivo and in vitro studies using the W288F and W288A variants of GlxA to assess the role of Trp288 on the morphology, maturation, spectroscopic and enzymatic properties. Our findings point towards a salient role for Trp288 in the kinetics of copper loading and maturation of GlxA, with its presence essential for stabilising the metalloradical site required for coupling catalytic activity and morphological development
The role of antimicrobial stewardship programmes in children: a systematic review.
The United Nations and the World Health Organization have designated antimicrobial resistance (AMR) as a major health priority and developed action plans to reduce AMR in all healthcare settings. Establishment of institutional antimicrobial stewardship programmes (ASPs) is advocated as a key intervention to reduce antibiotic consumption in hospitals and address high rates of multi-drug resistant (MDR) bacteria. We searched PUBMED and the Cochrane database of systematic reviews (1/2007-3/2017) to identify studies reporting about the effectiveness of ASPs in general paediatric wards and paediatric intensive care units (PICU), on reducing antibiotic consumption, on using broad spectrum/restricted antibiotics, and on antibiotic resistance and healthcare-associated infections (HAIs). Neonatal units and antifungal agents were excluded. Of 2509 titles and abstracts, nine articles were eligible to be included in the final analysis. All studies reported on the reduction of broad spectrum/restricted antibiotics or antibiotic consumption. One study reported on the reduction of HAI in a PICU, and another evaluated bacterial resistance, showing no effect following ASP implementation. Prospective audit on antibiotic use was the most common ASP core component (eight of nine studies). Antibiotic pre-authorisation was described in two articles. Other described interventions were providing guidelines or written information (five of nine articles), and training of healthcare professionals (one article). There is limited evidence about reducing antibiotic consumption and broad-spectrum/restricted agents following ASP implementation, specifically in PICU. Data evaluating the impact of ASPs on HAI and AMR in PICU is lacking. In addition, there is limited information on effective components of a successful ASPs in PICUs
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