1,658 research outputs found
Can tuition fees be justified? A break-even analysis of the financial statements of UK universities
working pape
Influences on the fraction of hydrophobic and hydrophilic black carbon in the atmosphere
Black carbon (BC) is a short term climate forcer that directly warms the atmosphere, slows convection, and hinders quantification of the effect of greenhouse gases on climate change. The atmospheric lifetime of BC particles with respect to nucleation scavenging in clouds is controlled by their ability to serve as cloud condensation nuclei (CCN). To serve as CCN under typical conditions, hydrophobic BC particles must acquire hygroscopic coatings. However, the quantitative relationship between coatings and hygroscopic properties for ambient BC particles is not known nor is the time scale for hydrophobic-to-hydrophilic conversion. Here we introduce a method for measuring the hygroscopicity of externally and internally mixed BC particles by coupling a single particle soot photometer with a humidified tandem differential mobility analyzer. We test this technique using uncoated and coated laboratory generated model BC compounds and apply it to characterize the hygroscopicity distribution of ambient BC particles. From these data we derive that the observed number fraction of BC that is CCN active at 0.2% supersaturation is generally low in an urban area near sources and that it varies with the trajectory of the airmass. We anticipate that our method can be combined with measures of air parcel physical and photochemical age to provide the first quantitative estimates for characterizing hydrophobic-to-hydrophilic conversion rates in the atmosphere.Peer reviewe
Fibrillar Elastomeric Micropatterns Create Tunable Adhesion Even to Rough Surfaces
Acknowledgements V.B., N.K.G., and E.A. contributed with conception and experimental design. V.B. performed the experiments. V.B., R.H., A.G., and R.M.M. carried out analysis and interpretation of data. V.B., R.H., A.G., and E.A. wrote the manuscript. V.B. and R.H. contributed equally to this work. V.B. acknowledges funding by SPP 1420 of the German Science Foundation DFG. E.A., N.K.G., and R.H. acknowledge funding from the European Research Council under the European Union/ERC Advanced Grant “Switch2Stick,” Agreement No. 340929.Peer reviewedPublisher PD
An examination of international accounting standard-setting due process and the implications for legitimacy
NOTICE: this is the author’s version of a work that was accepted for publication in British Accounting Review. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in British Accounting ReviewThis paper explores accounting standard-setting by focusing on relative levels of stakeholder and jurisdictional influence in the financial instruments disclosure reporting due process. We draw on legitimacy theory to explain our findings and ask what implications any bias might have for the IASB. This study extends the standard-setting literature in three ways. First, we create a weighted coding system to analyse the content of comment letters. Second, we test for differences in the success rate of comments made by stakeholders and by jurisdictions. Third, we analyse IASB discussion documentation that sheds light on the decision-making process. Previous studies have focused on whether outcome-oriented proposals are ‘influential’ (persuasive) by focusing on success rates measured as proposed changes being accepted. We widen this definition to include whether constituents views are discussed. We find that accounting firms appear to have significantly less influence than other stakeholders. We also find that the IASB reacts less favourably to UK proposals but comments from the US are more likely to be discussed. A lack of fairness (real or perceived) could jeopardise perceptions of the standard-setting due process’ procedural legitimacy and ultimately the IASB’s cognitive legitimacy
Enhanced differentiation of human embryonic stem cells towards definitive endoderm on ultrahigh aspect ratio nanopillars
Differentiation of human embryonic stem cells is widely studied as a potential unlimited source for cell replacement therapy to treat degenerative diseases such as diabetes. The directed differentiation of human embryonic stem cells relies mainly on soluble factors. Although, some studies have highlighted that the properties of the physical environment, such as substrate stiffness, affect cellular behavior. Here, mass-produced, injection molded polycarbonate nanopillars are presented, where the surface mechanical properties, i.e., stiffness, can be controlled by the geometric design of the ultrahigh aspect ratio nanopillars (stiffness can be reduced by 25.0003). It is found that tall nanopillars, yielding softer surfaces, significantly enhance the induction of definitive endoderm cells from pluripotent human embryonic stem cells, resulting in more consistent differentiation of a pure population compared to planar control. By contrast, further differentiation toward the pancreatic endoderm is less successful on “soft” pillars when compared to “stiff” pillars or control, indicating differential cues during the different stages of differentiation. To accompany the mechanical properties of the nanopillars, the concept of surface shear modulus is introduced to describe the characteristics of engineered elastic surfaces through micro or nanopatterning. This provides a framework whereby comparisons can be drawn between such materials and bulk elastomeric materials
Simulation of the cytoskeletal response of cells on grooved or patterned substrates.
We analyse the response of osteoblasts on grooved substrates via a model that accounts for the cooperative feedback between intracellular signalling, focal adhesion development and stress fibre contractility. The grooved substrate is modelled as a pattern of alternating strips on which the cell can adhere and strips on which adhesion is inhibited. The coupled modelling scheme is shown to capture some key experimental observations including (i) the observation that osteoblasts orient themselves randomly on substrates with groove pitches less than about 150 nm but they align themselves with the direction of the grooves on substrates with larger pitches and (ii) actin fibres bridge over the grooves on substrates with groove pitches less than about 150 nm but form a network of fibres aligned with the ridges, with nearly no fibres across the grooves, for substrates with groove pitches greater than about 300 nm. Using the model, we demonstrate that the degree of bridging of the stress fibres across the grooves, and consequently the cell orientation, is governed by the diffusion of signalling proteins activated at the focal adhesion sites on the ridges. For large groove pitches, the signalling proteins are dephosphorylated before they can reach the regions of the cell above the grooves and hence stress fibres cannot form in those parts of the cell. On the other hand, the stress fibre activation signal diffuses to a reasonably spatially homogeneous level on substrates with small groove pitches and hence stable stress fibres develop across the grooves in these cases. The model thus rationalizes the responsiveness of osteoblasts to the topography of substrates based on the complex feedback involving focal adhesion formation on the ridges, the triggering of signalling pathways by these adhesions and the activation of stress fibre networks by these signals.A.V. and V.S.D. acknowledge the Royal Society for supporting A.V. through a Newton International Fellowship.This is the accepted manuscript of a paper published in the Journal of the Royal Society Interface (Vigliotti A, McMeeking RM, Deshpande VS, J. R. Soc. Interface 2015, 12, 20141320, doi:10.1098/rsif.2014.1320). The final version is available at http://dx.doi.org/10.1098/rsif.2014.1320
Airborne observations of aerosol microphysical properties and particle ageing processes in the troposphere above Europe
In-situ measurements of aerosol microphysical properties were performed in May 2008 during the EUCAARI-LONGREX campaign. Two aircraft, the FAAM BAe-146 and DLR Falcon 20, operated from Oberpfaffenhofen, Germany. A comprehensive data set was obtained comprising the wider region of Europe north of the Alps throughout the whole tropospheric column. Prevailing stable synoptic conditions enabled measurements of accumulating emissions inside the continental boundary layer reaching a maximum total number concentration of 19 000 particles cm<sup>−3</sup> stp. Ultra-fine particles as indicators for nucleation events were observed within the boundary layer during high pressure conditions and after updraft of emissions induced by frontal passages above 8 km altitude in the upper free troposphere. Aerosol ageing processes during air mass transport are analysed using trajectory analysis. The ratio of particles containing a non-volatile core (250 °C) to the total aerosol number concentration was observed to increase within the first 12 to 48 h from the particle source from 50 to 85% due to coagulation. Aged aerosol also features an increased fraction of accumulation mode particles of approximately 40% of the total number concentration. The presented analysis provides an extensive data set of tropospheric aerosol microphysical properties on a continental scale which can be used for atmospheric aerosol models and comparisons of satellite retrievals
The determinants of the UK Big Firms Premium
Our study attempts to determine whether, and if so why, the large auditing firms are able to earn a premium on their audit work in the UK. We start by confirming the apparent existence of a Big Firm premium during the period 1985-2002. We examine industry specialisation, non audit service fee and monopoly pricing explanations for the premium. The results of our tests of industry specialisation are mixed. There is little evidence that this premium is associated with industry specialisation when specialists are defined at the national level. Significant premium are observed if specialisation is defined at the city level, particularly if the auditor is the industry leader. However, when appropriate allowance is made for endogeneity, by modelling both audit and non-audit fees in a simultaneous equations framework, the Big Firm premium disappears. We find evidence to suggest that non audit fees earned by auditors from their audit clients are positively related to the size of the audit size and vice versa. Finally, when the sample is stratified by the size of audit client, we find no systematic evidence of anti-competitive pricing
The Rayleigh-Lamb wave propagation in dielectric elastomer layers subjected to large deformations
The propagation of waves in soft dielectric elastomer layers is investigated.
To this end incremental motions superimposed on homogeneous finite deformations
induced by bias electric fields and pre-stretch are determined. First we
examine the case of mechanically traction-free layer, which is an extension of
the Rayleigh-Lamb problem in the purely elastic case. Two other loading
configurations are accounted for too. Subsequently, numerical examples for the
dispersion relations are evaluated for a dielectric solid governed by an
augmented neo-Hookean strain energy. It is found that the the phase speeds and
frequencies strongly depend on the electric excitation and pre-stretch. These
findings lend themselves at the possibility of controlling the propagation
velocity as well as filtering particular frequencies with suitable choices of
the electric bias field
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