47,243 research outputs found
Audit exemption and the demand for voluntary audit: A comparative study of the UK and Denmark
No full textThis is the accepted version of the following article: Collis, J. (2010), Audit Exemption and the Demand for Voluntary Audit: A Comparative Study of the UK and Denmark. International Journal of Auditing, 14: 211–231, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1111/j.1099-1123.2010.00415.x/abstract.This study investigates the sufficiency of turnover as a surrogate for demand for voluntary audit and compares the determinants in the UK and Denmark. Empirical data for the study were drawn from government surveys of the directors of small private companies in both countries, which were based on the same research instrument, Bivariate tests support the hypothesised effects of turnover and a range of firm-specific factors suggested by economic rationality and agency theory. The main contribution of the study is the finding that turnover alone is not a sufficient surrogate for the costs and benefits of audit. The main predictors are turnover and a slightly different combination of management and agency factors in each country. The study provides a model that can be tested in other jurisdictions and its findings should be of interest to the accountancy profession and national regulators planning to introduce or revise audit exemption for small companies
A localised co-rotating auroral absorption event observed near noon using imaging riometer and EISCAT
No full textInternational audienceAn isolated region of energetic electron precipitation observed near local noon in the auroral zone has been investigated using imaging riometer (IRIS) and incoherent-scatter radar (EISCAT) techniques. IRIS revealed that the absorption event was essentially co-rotating with the Earth for about 2 h. The spatial and temporal variations in D-region electron density seen by EISCAT were able to be interpreted within a proper context when compared with the IRIS data. EISCAT detected significant increases in electron density at altitudes as low as 65 km as the event drifted through the radar beam. The altitude distribution of incremental radio absorption revealed that more than half of the absorption occurred below 75 km, with a maximum of 67 km. The energy spectrum of the precipitating electrons was highly uniform throughout the event, and could be described analytically by the sum of three exponential distributions with characteristic energies of 6, 70 and 250 keV. A profile of effective recombination coefficient that resulted in self-consistent agreement between observed electron desities and those inferred from an inversion procedure has been deduced. The observations suggest a co-rotating magnetospheric source region on closed dayside field lines. However, a mechanism is required that can sustain such hard precipitation for the relatively long duration of the event
Windows to cell function and dysfunction: signatures written in the boundary layers
No full textThe medium surrounding cells either in culture or in tissues contains a chemical mix varying with cell state. As solutes move in and out of the cytoplasmic compartment they set up characteristic signatures in the cellular boundary layers. These layers are complex physical and chemical environments the profiles of which reflect cell physiology and provide conduits for intercellular messaging. Here we review some of the most relevant characteristics of the extracellular/intercellular space. Our initial focus is primarily on cultured cells but we extend our consideration to the far more complex environment of tissues, and discuss how chemical signatures in the boundary layer can or may affect cell function. Critical to the entire essay are the methods used, or being developed, to monitor chemical profiles in the boundary layers. We review recent developments in ultramicro electrochemical sensors and tailored optical reporters suitable for the task in hand
Doped Ceria Catalysts for NOx Storage and Reduction
No full textThe new Euro 7 protocol, proposed by the Commission on 26th October 2022, concerning emissions of leanburn engines, presents a need for further optimisation of existing after-treatment technologies. It reveals a 35% reduction to the NOx emission limit for cars and vans, compared to Euro 6 . A well-known technology employed to reduce NOx to clean emissions in light-duty vehicles is the Lean NOx Trap (LNT). LNTs employ catalysts consisting of PGMs supported on ceria (CeO2) or other mixed oxides. Ceria’s redox property makes it an attractive selection, as well as its ability to store NOx at low temp (<300 ̊C), especially when Pt is present. Storage properties of ceria can be further enhanced by doping. Dopants reportedly allow ceria to function better at low temperature (<300 ̊C), and to reduce the PGM loading required to achieve the same conversion efficiencies. The RE metals Sm, Pr and Nd have been employed as dopants on CeO2 for LNT applications to increase surface oxygen content, oxygen vacancies, defect densities, and cause changes to the Pt-ceria interaction. These structural changes can allow for higher NSC during lean operation and enhanced activation during rich purge. Sm, Pr and Nd doped catalysts (10 wt.%) were synthesised on a range of ceria based catalysts with different Pt loadings (0-1 wt.%). Morphological changes observed through dopant addition has been investigated and related to catalytic performance increases.
Ion trapping with fast-response ion-selective microelectrodes enhances detection of extracellular ion channel gradients
No full textPreviously, functional mapping of channels has been achieved by measuring the passage of net charge and of specific ions with electrophysiological and intracellular fluorescence imaging techniques. However, functional mapping of ion channels using extracellular ion-selective microelectrodes has distinct advantages over the former methods. We have developed this method through measurement of extracellular K+ gradients caused by efflux through Ca2+-activated K+ channels expressed in Chinese hamster ovary cells. We report that electrodes constructed with short columns of a mechanically stable K+-selective liquid membrane respond quickly and measure changes in local [K+] consistent with a diffusion model. When used in close proximity to the plasma membrane (<4 µm), the ISMs pose a barrier to simple diffusion, creating an ion trap. The ion trap amplifies the local change in [K+] without dramatically changing the rise or fall time of the [K+] profile. Measurement of extracellular K+ gradients from activated rSlo channels shows that rapid events, 10–55 ms, can be characterized. This method provides a noninvasive means for functional mapping of channel location and density as well as for characterizing the properties of ion channels in the plasma membrane
Results of left thoracoscopic Collis gastroplasty with laparoscopic Nissen fundoplication for the surgical treatment of true short oesophagus in gastro-oesophageal reflux disease and Type III-IV hiatal hernia.
No full textAbstract
OBJECTIVES:
Controversy exists regarding surgery for true short oesophagus (TSOE). We compared the results of thoracoscopic Collis gastroplasty-laparoscopic Nissen procedure for the treatment of TSOE with the results of standard laparoscopic Nissen fundoplication.
METHODS:
Between 1995 and 2013, the Collis-Nissen procedure was performed in 65 patients who underwent minimally invasive surgery when the length of the abdominal oesophagus, measured intraoperatively after maximal oesophageal mediastinal mobilization, was ≤1.5 cm. The results of the Collis-Nissen procedure were frequency-matched according to age, sex and period of surgical treatment with those of 65 standard Nissen fundoplication procedures in patients with a length of the abdominal oesophagus >1.5 cm. Postoperative mortality and morbidity were evaluated according to the Accordion classification. The patients underwent a timed clinical-instrumental follow-up that included symptoms assessment, barium swallow and endoscopy. Symptoms, oesophagitis and global results were graded according to semi-quantitative scales. The results were considered to be excellent in the absence of symptoms and oesophagitis, good if symptoms occurred two to four times a month in the absence of oesophagitis, fair if symptoms occurred two to four times a week in the presence of hyperaemia, oedema and/or microscopic oesophagitis and poor if symptoms occurred on a daily basis in the presence of any grade of endoscopic oesophagitis, hiatal hernia of any size or type, or the need for antireflux medical therapy. The follow-up time was calculated from the time of surgery to the last complete follow-up.
RESULTS:
The postoperative mortality rate was 1.5% for the Collis-Nissen and 0 for the Nissen procedure. The postoperative complication rate was 24% for the Collis-Nissen and 7% for Nissen (P = 0.001) procedure. The complication rate for the Collis-Nissen procedure was 43% in the first 32 cases and 6% in the last 33 cases (P < 0.0001). The median follow-up period was 96 months. The results were: excellent in 27% of Collis-Nissen and 29% of Nissen; good in 64% of Collis-Nissen and 55% of Nissen; fair in 3% of Collis-Nissen and 11% of Nissen and poor in 6% of Collis-Nissen and 5% of Nissen (P = 0.87).
CONCLUSIONS:
In patients affected by a TSOE, the Collis-Nissen procedure may achieve equally satisfactory results as the standard Nissen procedure in uncomplicated patients.
CLINICAL REGISTRATION NUMBER:
NCT02288988
p-n Junction Formation in i-Ge Crystal by Laser Radiation
No full textP-n junction is the main component of many semiconductor devices. Thermodiffusion, ion implantation and molecular beam epitaxy are only a few methods to form a p-n junction. The main drawback for these methods is high cost per p-n junction since the equipment for these methods is expensive. A possibility of p-n junction formation by laser radiation was shown in several p- and n-type semiconductors: p-Si[1,2], p-CdTe[3], p-InSb[4,5], p-InAs[6], p-PbSe[7] and p-Ge[8] due to inversion of conductivity type. Unfortunately, the mechanism of p-n junction formation by laser radiation is not clear until now.
In the present research rectification effect of current-voltage characteristic in pure intrinsic Ge crystal after irradiation by Nd:YAG laser was observed. The effect is characterised by threshold intensity of the laser radiation. Increase of rectification ratio of current-voltage characteristics and barrier height with intensity of the laser radiation, energy of laser radiation quanta and number of pulses was observed in this experiment. The mechanism of this phenomenon is explained by generation and redistribution of intrinsic point defects in temperature gradient field, which causes strongly absorbed laser radiation. The redistribution of defects takes place because interstitial atoms drift towards the irradiated surface, but vacancies drift in the opposite direction – in the bulk of semiconductor according to Thermogradient effect. Since interstitials in Ge crystal are of n-type and vacancies are known to be of p-type, a p-n junction is formed.
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[5] A. Medvid‘ et al. Vacuum, 51, 245 (1998).
[6] L. Kurbatov et al. Reports of Acad. Sc.USSR, 268, 594 (1983)
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Acknowledgments.
The author gratefully acknowledges financial support in part by Europe Project in the Framework of MATERA+ project, European Regional Development Fund within the project “Sol-gel and laser technologies for the development of nanostructures and barrier structures”, the ESF Projects No. 1DP/1.1.1.2.0/09/ APIA/VIAA/142 and «Support for the implementation of doctoral studies at Riga Technical University»
Experimental investigation into the effect of substrate clamping on the piezoelectric behaviour of thick-film PZT elements
No full textThis paper details an experimental investigation of the clamping effect associated with thick-film piezoelectric elements printed on a substrate. The clamping effect reduces the measured piezoelectric coefficient, d33, of the film. This reduction is due to the influence of the d31 component in the film when a deformation of the structure occurs, by either the direct or indirect piezoelectric effect. Theoretical analysis shows a reduction in the measured d33 of 62%, i.e. a standard bulk lead zirconate titanate (PZT)-5H sample with a manufacturer specified d33 of 593pC/N would fall to 227.8pC/N. To confirm this effect, the d33 coefficients of five thin bulk PZT-5H samples of 220µm thickness were measured before and after their attachment to a metallized 96% alumina substrate. The experimental results show a reduction in d33 of 74% from 529pC/N to 139pC/N. The theoretical analysis was then applied to existing University of Southampton thick-film devices. It is estimated that the measured d33 value of 131pC/N of the thick-film devices is the equivalent of an unconstrained d33 of 345pC/N
Designing small molecule polyaromatic p- and n-type semiconductor materials for organic electronics
No full textBy combining computational aided design with synthetic chemistry, we are able to identify core 2D polyaromatic small molecule templates with the necessary optoelectronic properties for p- and n-type materials. By judicious selection of the functional groups, we can tune the physical properties of the material making them amenable to solution and vacuum deposition. In addition to solubility, we observe that the functional group can influence the thin film molecular packing. By developing structure-property relationships (SPRs) for these families of compounds we observe that some compounds are better suited for use in organic solar cells, while others, varying only slightly in structure, are favoured in organic field effect transistor devices. We also find that the processing conditions can have a dramatic impact on molecular packing (i.e. 1D vs 2D polymorphism) and charge mobility; this has implications for material and device long term stability. We have developed small molecule p- and n-type materials for organic solar cells with efficiencies exceeding 2%. Subtle variations in the functional groups of these materials produces p- and ntype materials with mobilities higher than 0.3 cm2/Vs. We are also interested in using our SPR approach to develop materials for sensor and bioelectronic applications.Research was undertaken through CSIRO’s Flexible Electronics Theme. ABH, GEC, YS, SM, and AB acknowledgeCSIRO OCE for financial support. The author acknowledges all the work and effort of the co-authors on thesepublications from CSIRO, the Australian Synchrotron, and Australian (University of Melbourne, Monash University,University of Newcastle and University of Warwick) and international collaborators (Wake Forest University, USA;Georgia Institute of Technology, USA; and King Abdullah University of Science and Technology, KSA)
Une chronologie nouvelle des bronzes et potins gaulois : V. Guichard, P. Pion, F. Malacher et J. Collis, À propos de la circulation monétaire en Gaule Chevelue aux IIe et Ier siècles av.J.-C
No full textRichard Jean-Claude. Une chronologie nouvelle des bronzes et potins gaulois : V. Guichard, P. Pion, F. Malacher et J. Collis, À propos de la circulation monétaire en Gaule Chevelue aux IIe et Ier siècles av.J.-C. In: Dialogues d'histoire ancienne, vol. 20, n°2, 1994. pp. 430-433
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