4,145 research outputs found
On the equivalence of Eulerian and Lagrangian variables for the two-component Camassa-Holm system
The Camassa-Holm equation and its two-component Camassa-Holm system
generalization both experience wave breaking in finite time. To analyze this,
and to obtain solutions past wave breaking, it is common to reformulate the
original equation given in Eulerian coordinates, into a system of ordinary
differential equations in Lagrangian coordinates. It is of considerable
interest to study the stability of solutions and how this is manifested in
Eulerian and Lagrangian variables. We identify criteria of convergence, such
that convergence in Eulerian coordinates is equivalent to convergence in
Lagrangian coordinates. In addition, we show how one can approximate global
conservative solutions of the scalar Camassa-Holm equation by smooth solutions
of the two-component Camassa-Holm system that do not experience wave breaking
Evaluating STZ-Induced Impaired Wound Healing in Rats
YesMedical Research Council, Innovate UK and Epistem Ltd
Enhanced nasopharyngeal infection and shedding associated with an epidemic lineage of emm3 group A Streptococcus
Background:
A group A Streptococcus (GAS) lineage of genotype emm3, sequence type 15 (ST15) was
associated with a six month upsurge in invasive GAS disease in the UK. The epidemic lineage
(Lineage C) had lost two typical emm3 prophages, Φ315.1 and Φ315.2 associated with the
superantigen ssa, but gained a different prophage (ΦUK-M3.1) associated with a different
superantigen, speC and a DNAse spd1.
Methods and Results:
The presence of speC and spd1 in Lineage C ST15 strains enhanced both in vitro mitogenic
and DNAse activities over non-Lineage C ST15 strains. Invasive disease models in Galleria
mellonella and SPEC-sensitive transgenic mice, revealed no difference in overall invasiveness
of Lineage C ST15 strains compared to non-Lineage C ST15 strains, consistent with clinical
and epidemiological analysis. Lineage C strains did however markedly prolong murine nasal
infection with enhanced nasal and airborne shedding compared to non-Lineage C strains.
Deletion of speC or spd1 in two Lineage C strains identified a possible role for spd1 in airborne
shedding from the murine nasopharynx.
Conclusions:
Nasopharyngeal infection and shedding of Lineage C strains was enhanced compared to nonLineage
C strains and this was, in part, mediated by the gain of the DNase spd1 through prophage acquisition
Spectroscopic Observations of Optically Selected Clusters of Galaxies from the Palomar Distant Cluster Survey
We have conducted a redshift survey of sixteen cluster candidates from the
Palomar Distant Cluster Survey (PDCS) to determine both the density of PDCS
clusters and the accuracy of the estimated redshifts presented in the PDCS
catalog (Postman et. al. 1996). We find that the matched-filter redshift
estimate presented in the PDCS has an error sigma_z = 0.06 in the redshift
range 0.1 < z < 0.35 based on eight cluster candidates with three or more
concordant galaxy redshifts.
We measure the low redshift (0.1 < z < 0.35) space density of PDCS clusters
to be 31.3^{+30.5}_{-17.1} * E-06 h^3 Mpc^-3 (68% confidence limits for a
Poisson distribution) for Richness Class 1 systems. We find a tentative space
density of 10.4^{+23.4}_{-8.4}* E-06 h^3 Mpc^-3 for Richness Class 2 clusters.
These densities compare favorably with those found for the whole of the PDCS
and support the finding that the space density of clusters in the PDCS is a
factor of ~5 above that of clusters in the Abell catalog (Abell 1958; Abell,
Corwin, and Olowin 1989). These new space density measurements were derived as
independently as possible from the original PDCS analysis and therefore,
demonstrate the robustness of the original work. Based on our survey, we
conclude that the PDCS matched-filter algorithm is successful in detecting real
clusters and in estimating their true redshifts in the redshift range we
surveyed.Comment: 23 pages with 4 figures and 3 seperate tables. To be published in the
November Issue of the Astronomical Journa
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Using scenarios to explore UK upland futures
Uplands around the world are facing significant social, economic and environmental changes, and decision-makers need to better understand what the future may hold if they are to adapt and maintain upland goods and services. This paper draws together all major research comprising eight studies that have used scenarios to describe possible futures for UK uplands. The paper evaluates which scenarios are perceived by stakeholders to be most likely and desirable, and assesses the benefits and drawbacks of the scenario methods used in UK uplands to date. Stakeholders agreed that the most desirable and likely scenario would be a continuation of hill farming (albeit at reduced levels) based on cross-compliance with environmental measures. The least desirable scenario is a withdrawal of government financial support for hill farming. Although this was deemed by stakeholders to be the least likely scenario, the loss of government support warrants close attention due to its potential implications for the local economy. Stakeholders noted that the environmental implications of this scenario are much less clear-cut. As such, there is an urgent need to understand the full implications of this scenario, so that upland stakeholders can adequately prepare, and policy-makers can better evaluate the likely implications of different policy options. The paper concludes that in future, upland scenario research needs to: (1) better integrate in-depth and representative participation from stakeholders during both scenario development and evaluation; and (2) make more effective use of visualisation techniques and simulation models
Cl 1205+44, a fossil group at z = 0.59
This is a report of Chandra, XMM-Newton, HST and ARC observations of an
extended X-ray source at z = 0.59. The apparent member galaxies range from
spiral to elliptical and are all relatively red (i'-Ks about 3). We interpret
this object to be a fossil group based on the difference between the brightness
of the first and second brightest cluster members in the i'-band, and because
the rest-frame bolometric X-ray luminosity is about 9.2x10^43 h70^-2 erg s^-1.
This makes Cl 1205+44 the highest redshift fossil group yet reported. The
system also contains a central double-lobed radio galaxy which appears to be
growing via the accretion of smaller galaxies. We discuss the formation and
evolution of fossil groups in light of the high redshift of Cl 1205+44.Comment: 21 pages, 13 figures, minor corrections to match published ApJ
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Building professional discourse in emerging markets: Language, context and the challenge of sensemaking
Using ethnographic evidence from the former Soviet republics, this article examines a relatively new and mainly unobserved in the International Business (IB) literature phenomenon of communication disengagement that manifests itself in many emerging markets. We link it to the deficiencies of the local professional business discourse rooted in language limitations reflecting lack of experience with the market economy. This hampers cognitive coherence between foreign and local business entities, adding to the liability of foreignness as certain instances of professional experience fail to find adequate linguistic expression, and complicates cross-cultural adjustments causing multi-national companies (MNCs) financial losses. We contribute to the IB literature by examining cross-border semantic sensemaking through a retrospectively constructed observational study. We argue that a relative inadequacy of the national professional idiom is likely to remain a feature of business environment in post-communist economies for some time and therefore should be factored into business strategies of MNCs. Consequently, we recommend including discursive hazards in the risk evaluation of international projects
Developmental Testing of Habitability and Human Factors Tools and Methods During Neemo 15
Currently, no established methods exist to collect real-time human factors and habitability data while crewmembers are living aboard the International Space Station (ISS), traveling aboard other space vehicles, or living in remote habitats. Currently, human factors and habitability data regarding space vehicles and habitats are acquired at the end of missions during postflight crew debriefs. These debriefs occur weeks or often longer after events have occurred, which forces a significant reliance on incomplete human memory, which is imperfect. Without a means to collect real-time data, small issues may have a cumulative effect and continue to cause crew frustration and inefficiencies. Without timely and appropriate reporting methodologies, issues may be repeated or lost. TOOL DEVELOPMENT AND EVALUATION: As part of a directed research project (DRP) aiming to develop and validate tools and methods for collecting near real-time human factors and habitability data, a preliminary set of tools and methods was developed. These tools and methods were evaluated during the NASA Extreme Environments Mission Operations (NEEMO) 15 mission in October 2011. Two versions of a software tool were used to collect observational data from NEEMO crewmembers that also used targeted strategies for using video cameras to collect observations. Space habitability observation reporting tool (SHORT) was created based on a tool previously developed by NASA to capture human factors and habitability issues during spaceflight. SHORT uses a web-based interface that allows users to enter a text description of any observations they wish to report and assign a priority level if changes are needed. In addition to the web-based format, a mobile Apple (iOS) format was implemented, referred to as iSHORT. iSHORT allows users to provide text, audio, photograph, and video data to report observations. iSHORT can be deployed on an iPod Touch, iPhone, or iPad; for NEEMO 15, the app was provided on an iPad2
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