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Toward nanoxerography on silicon oxide : tip induced oxidation, surface charge retention, and charge directed vapour phase deposition
Get PDFNanoxerography is the method by which particles in the region 1-100nm can be selectively assembled on a surface through the use of a charge pattern, necessitating a substrate that can receive and hold a charge. Silicon oxide has such properties as well as being a material of significant interest within the electronics industry and in nanotechnological settings, but has not, as yet, been used for nanoxerography. Before an attempt at nanoxerography on silicon oxide, it was necessary to determine optimal parameters for charge storage on silicon oxide, the literature indicating oxide thickness to be key. Tip induced oxidation (TIO) was employed to locally vary oxide thickness after characterisation of physical and electrical properties.
Characterisation of TIO platforms was performed using atomic force microscopy showing that TIO produced oxides, while different from the native oxide, were sufficiently similar for nanoxerography. Growth parameters of TIO through an oxide layer were found to be similar to parameters of TIO on bare silicon. Through this investigation dielectric breakdown appeared to play a role in TIO, and the method of breakdown depends on whether AC or DC TIO is used.
Surface charge retention was investigated on ultrathin TIO oxide platforms revealing that lateral charge spreading was independent of oxide thickness, while diffusion through the oxide depended on thickness. The surface properties were shown to have a significant impact on the rate of surface charge diffusion; changing the substrate to sapphire, or applying a bilayer of didodecyldimethylammonium bromide (DDAB), significantly altered charge diffusion.
Nanoxerography was attempted in liquid environments using DDAB liposomes two different ‘developer’ solutions – water and ethanol – neither proving ideal. Vapour phase deposition of DDAB was shown to be a viable method for creating a bilayer of DDAB on silicon oxide and vapour phase nanoxerography using DDAB was shown to achieve partially selective deposition
Multiple credit ratings and liquidity creation
Get PDFWe examine the relationship between multiple credit rating purchases by banks and liquidity creation using a diverse sample of 486 banks from 71 countries. We show that liquidity creation is negatively associated with the number of ratings purchased by the bank, and that capital can positively moderate this relationship, allowing banks that obtain more ratings to create more liquidity.Peer reviewe
International cooperation and Kantian moral behaviour : complements or substitutes?
Get PDFFaced with a global emissions problem such as climate change, we know that if countries’ emissions decisions are made in an independent and self-interested fashion the outcome can be very far from optimal. One proposed solution is to have countries enter international environmental agreements (IEAs) whereby individual countries’ emissions decisions are taken in the interests of all the participating countries and so reflect a degree of altruism. However, if the decision to co-operate is made in a self-interested fashion the standard non-cooperative model of IEAs yields the pessimistic conclusion that the more serious the environmental problem the smaller will be the equilibrium membership of an IEA. Our paper examines the implications for emissions, IEA membership and welfare of assuming that countries make both emissions and IEA membership decisions in the alternative moral fashion of acting as imperfect Kantians as defined by Alger and Weibull (2013). We show that (i) the first-best can be achieved when countries either act as Perfect Kantians or by fully cooperating; (ii) in a more imperfect setting, these two forms of moral behaviour are complementary approaches to improving welfare outcomes in the sense that the greater the weights on Kantian behaviour the larger is the equilibrium coalition; (iii) the weights on Kantian behaviour that will induce full cooperation and hence the first-best are significantly less than 1; (iv) for given Kantian weights, our model generates higher equilibrium IEA membership, lower emissions and higher welfare than in the related paper by Eichner and Pethig (2022: 'International environmental agreements when countries behave morally') which, we argue, does not fully capture the benefits of membership decisions.Peer reviewe
A note on the Wilcoxon-Mann-Whitney test and tied observations
Get PDFRecently, it was recommended to omit tied observations before applying the two-sample Wilcoxon-Mann-Whitney test McGee M. et al. (2018). Using a simulation study, we argue for exact tests using all the data (including tied values) as a preferable approach. Exact tests, with tied observations included guarantee the type I error rate with a better exploitation of the significance level and a larger power than the corresponding tests after the omission of tied observations. The omission of ties can produce a considerable change in the shape of the sample, and so can violate underlying test assumptions. Thus, on both theoretical and practical grounds, the recommendation to omit tied values cannot be supported, relative to analysing the whole data set in the same way whether or not ties occur, preferably with an exact permutation test.Peer reviewe
'Not a party to this crime' : the reciprocal constitution of identity and morality by signatories of the 'Academics for Peace' petition in Turkey
Get PDFIn this paper, we examine how social identity, moral obligation and the relationship between the two shaped support for the 2016 Academics for Peace petition in Turkey. We examine the pre-trial statements of nine defendants charged for signing the petition and appearing in court on the same day in December 2018. We first conduct an inductive thematic analysis on one statement, and then, using the themes from this analysis, we conducted a deductive thematic analysis on the remaining eight statements. In line with the existing studies, we find considerable evidence that social identity and moral obligation are invoked as key reasons for signing in this highly repressive context. However, rather than these being separate factors, the two are reciprocally constitutive. That is, social identities define moral obligations and, at the same time, enacting moral obligations defines identity (both the position of the individual in the group and the nature of the group in the world). In discussion, we consider the broader implications of a moralized view of social identities for our understanding of both collective action and social identity processes more generally.Peer reviewe
Workshop on mitigation measures to reduce bycatch of short-beaked common dolphins in the Bay of Biscay (WKEMBYC2)
Get PDFFollowing the special request from the DG MARE, the Workshop on mitigation measures to minimize bycatch of short-beaked common dolphins in the Bay of Biscay (WKEMBYC2) was established by ICES. WKEMBYC2 was tasked with updating and revaluating the scenarios previously proposed in the ICES special request advice in 2020. The group was asked to consider recent data on bycatch of common dolphins in commercial fisheries and total fishing effort in the Bay of Biscay and Iberian Coast ecosystem, as well as taking into account results from any mitigation trials carried out since the meeting in 2020. In section 2 of this report the efficacy of the scenarios provided during WKEMBYC in 2020 were reassessed using updated bycatch estimates calculated from at-sea monitoring and stranding data collected between 2019 and 2021. Scenarios and methods remained unchanged, to ensure comparability between both evaluations. Similarly, PBR values considered in the 2020 scenarios were again considered here, with the addition of the mPBR which was developed by OSPAR since the last workshop. The annual mortality due to bycatch inferred from French strandings in the Bay of Biscay and along the Western Channel was estimated at about 9,040 (95%CI [6,640 - 13,300]) common dolphins between 2019 and 2021. In the Bay of Biscay and Iberian Coast (areas 8 and 9), the mean annual bycatch estimated from at-sea observations between 2019-2021 across all métiers was 5938 (95% CI 3081-9700) common dolphins. The abundance estimate and PBR values used in this report were the same as those used in 2020; with common dolphin abundance estimated to be 634 286 (CV=0.307) for the European Atlantic Assessment Unit, and PBR for the species calcu-lated as 4926 individuals per year. The management objective of PBR is to ensure that “a population will remain at, or recover to, its maximum net productivity level (typically 50% of the populations carrying capacity), with 95% probability, within a 100-year period”. A modified PBR (mPBR) value of 985 was also used, with the management objective of ensuring “a population should be able to recover to or be maintained at 80% of carrying capacity, with probability 0.8, within a 100-year period”. Considering bycatch estimates calculated from at-sea monitoring, scenarios with a combination of pingers on OTM/PTB and at least 4-week closure in winter can reach the management objective of bycatch remaining below the PBR. The removal bycatch over a three-month period between the January and March winter period, and an addi-tional month closure in July/August potentially reduces bycatch below the mPBR level for at-sea monitoring bycatch estimates alone. Considering estimates inferred from strandings, a mini-mum of 6-week closure combined with pingers can achieve the objective of reducing bycatch below PBR. None of the scenarios can reduce bycatch below mPBR for either monitoring and stranding bycatch estimates. The narrower the fishery closure, the higher the risk of not achieving the management objective, as the peak of mortality can be missed. In section 3 of the report the workshop participants chose to further explore the scenarios with bycatch rates and estimate bycatch at a finer spatial and temporal scale and to consider additional mitigation measures based on results of newly conducted preliminary trials. This exploratory analysis allowed particular areas, métiers or periods with evidence of elevated bycatch rates to be identified at higher resolution, however, this approach requires significant at-sea monitoring in all strata. If such data were available, this method could be used to highlight specific areas, métiers and periods where particular effort in vessel observation should be deployed or mitigation measures implemented. WKEMBYC2 also recommended a series of monitoring actions to improve bycatch estimates, monitoring to data analysis, mitigation and the assessment of the northeast Atlantic common dolphin
Avoided metallicity in a hole-doped Mott insulator on a triangular lattice
Get PDFFunding: We gratefully acknowledge support from the UK Engineering and Physical Sciences Research Council (Grant Nos. EP/S005005/1 and EP/T02108X/1), the European Research Council (through the QUESTDO project, 714193), the Leverhulme Trust (Grant No. RL-2016-006), the Royal Society through the International Exchange grant IEC\R2\222041 and the Italian Ministry of Research through the PRIN-2022 “SORBET” project No.2022ZY8HJY. C.M.Y. acknowledges support from Shanghai Pujiang Talent Program 21PJ1405400 and TDLI Start-up Fund.Doping of a Mott insulator gives rise to a wide variety of exotic emergent states, from high-temperature superconductivity to charge, spin, and orbital orders. The physics underpinning their evolution is, however, poorly understood. A major challenge is the chemical complexity associated with traditional routes to doping. Here, we study the Mott insulating CrO2 layer of the delafossite PdCrO2, where an intrinsic polar catastrophe provides a clean route to doping of the surface. From scanning tunnelling microscopy and angle-resolved photoemission, we find that the surface stays insulating accompanied by a short-range ordered state. From density functional theory, we demonstrate how the formation of charge disproportionation results in an insulating ground state of the surface that is disparate from the hidden Mott insulator in the bulk. We demonstrate that voltage pulses induce local modifications to this state which relax over tens of minutes, pointing to a glassy nature of the charge order.Peer reviewe
Understanding spatial variation in fertility. An application of spatial statistical methods to fertility in Great Britain
No full textThis thesis provides an in-depth analysis of spatial fertility variation in Great Britain with a primary focus on empirical findings derived from applying spatially-explicit methodologies to longitudinal data. The research explores the influence of various determinants on spatial fertility patterns and examines the roles of compositional, contextual factors and diffusion. The existing theoretical literature on spatial variation in fertility suggests that ideological diffusion represents the most important long-term driver of fertility dynamics however empirical studies explicitly modelling this diffusion are rare within the literature.
Key empirical findings include significant spatial autocorrelation in the Total Fertility Rate (TFR) across Great Britain. This thesis extends the traditional urban-rural dichotomy in fertility variation. The thesis utilises a Spatial Durbin Panel Model to reveal the complex interplay between fertility rates and area characteristics, both within and between regions. It also finds evidence that diffusion processes play a significant role in the spatial patterning of fertility in Great Britain.
The thesis identifies several critical variables influencing spatial variation in fertility. Notably, unemployment within an area positively correlates with TFR, while neighbouring area’s unemployment negatively impacts fertility. This suggests a nuanced spatial mediation of unemployment on fertility decisions.
Another notable finding is the significant neighbourhood effects on fertility in Scotland, particularly for first births. This is evidenced by large spatial random effects even after accounting for individual-level characteristics and urban-rural classifications. Results show a significant proportion of this spatial effect can be attributed to a structured spatial effect. This thesis demonstrates the effectiveness of spatially explicit models in demography, notably in analysing the complex spatial dynamics of fertility. These empirical findings offer substantial insights into the spatial patterns of fertility in Great Britain, highlighting the importance of diffusion as a key determinant of spatial variation in fertility
Molecular asymmetry and rigidification as strategies to activate and enhance thermally activated delayed fluorescence in deep-blue MR-TADF emitters
Get PDFFunding; This work was supported financially by Kyulux Inc, JSPS Grant-in-Aid for Specially Promoted Research (23H05406), JST CREST (JPMJCR22B3), JSPS KAKENHI (23K20039), ESPRC (EP/R035164/1, EP/W007517/1), City University of Hong Kong (Project No. 9610637 and 9231531).Two novel deep-blue multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters, 1B-CzCrs and 2B-CzCrs, containing a fused carbazole unit were synthesized. The carbazole contributed to the emergence of TADF in these small molecules. Particularly, organic light-emitting diodes with 1B-CzCrs doped in the mCP host achieve a maximum external quantum efficiency of 12.8% at CIE coordinates of (0.146, 0.062).Peer reviewe
Decaying turbulence in molecular clouds : how does it affect filament networks and star formation?
Get PDFFunding: RJS gratefully acknowledges an STFC Ernest Rutherford fellowship (grant ST/N00485X/1) and HPC from the Durham DiRAC supercomputing facility (grants ST/P002293/1, ST/R002371/1, ST/S002502/1, and ST/R000832/1) without which this work would not have been possible.The fragmentation of gas to form stars in molecular clouds is intrinsically linked to the turbulence within them. These internal motions are set at the birth of the cloud and may vary with galactic environment and as the cloud evolves. In this paper, we introduce a new suite of 15 high-resolution 3D molecular cloud simulations using the moving mesh code AREPO to investigate the role of different decaying turbulent modes (mixed, compressive and solenoidal) and virial ratios on the evolution of a 104M⊙ molecular cloud. We find that diffuse regions maintain a strong relic of the initial turbulent mode, whereas the initial gravitational potential dominates dense regions. Solenoidal seeded models thus give rise to a diffuse cloud with filament-like morphology, and an excess of brown dwarf mass fragments. Compressive seeded models have an early onset of star-formation, centrally condensed morphologies and a higher accretion rate, along with overbound clouds. 3D filaments identified using DisPerSE and analyzed through a new Python toolkit we develop and make publicly available with this work called FIESTA, show no clear trend in lengths, masses and densities between initial turbulent modes. Overbound clouds, however, produce more filaments and thus have more mass in filaments. The hubs formed by converging filaments are found to favour star-formation, with surprisingly similar mass distributions independent of the number of filaments connecting the hub.Peer reviewe
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