Two Approaches to Dislocation Nucleation in the Supported Heteroepitaxial Equilibrium Islanding Phenomenon

We study the dislocation formation in 2D nanoscopic islands with two methods, the Molecular Static method and the Phase Field Crystal method. It is found that both methods indicate the same qualitative stages of the nucleation process. The dislocations nucleate at the film-substrate contact point and the energy decreases monotonously when the dislocations are farther away from the island-wetting film contact points than the distance of the highest energy barrier.Comment: 4 page

Theory of edge-state optical absorption in two-dimensional transition metal dichalcogenide flakes

We develop an analytical model to describe sub-band-gap optical absorption in two-dimensional semiconducting transition metal dichalcogenide (s-TMD) nanoflakes. The material system represents an array of few-layer molybdenum disulfide crystals, randomly orientated in a polymer matrix. We propose that optical absorption involves direct transitions between electronic edge states and bulk bands, depends strongly on the carrier population, and is saturable with sufficient fluence. For excitation energies above half the band gap, the excess energy is absorbed by the edge-state electrons, elevating their effective temperature. Our analytical expressions for the linear and nonlinear absorption could prove useful tools in the design of practical photonic devices based on s-TMDs.Royal Academy of Engineering, Collaborative Research Center 76

UK and EU subsidies and private R&D investment: Is there input additionality?

Business research and development (R&D) expenditures in the UK is low by international standards. To encourage investment, the UK government has been providing both direct and indirect support. The aim of this paper is to address four inter-related and policy-relevant questions: (i) what do we know about the UK regime for direct grant schemes? (ii) is the UK subsidy complementary or substitute for privately-funded R&D? (iii) does the UK funding regime differ from the EU regime in terms of selection and effect? (iv) does the scope for complementarity/additionality differ between different rates of funding? We address these questions using a rich dataset for more than 44 thousand UK firms from 1998-2012; and a range of treatment-effect estimators with and without control for selection. We report that the EU selection regime is more likely to support firms with long-term R&D plans. In addition, the UK subsidy is not associated with additionality, but the EU subsidy is. Finally, leverage estimations indicate that targeting a particular rate of subsidy is not likely to make a difference to private R&D effort in the UK subsidy case; but an increase in EU subsidy intensity does create leverage among firms that fall between the median and 75th percentile of the subsidy intensity distribution

COVID-19 & Quarantine Measures: A Comparison between India & Russia

The Governments of the different countries are taking a wide range of measures in response to the COVID-19 outbreak. For assessing the rigour of quarantine measures, the Blavatnik School of Government at the University of Oxford has launched the world`'s first COVID-19 government response tracker—the Oxford Coronavirus Government Response Tracker – OxCGRT). This tool aims to track and compare policy responses of governments around the world, rigorously and consistently. According to the COVID-19 Government Response Stringency Index (GRSI) the strictest measures are in India (97.37 points) and less stringent ones are in the Russian Federation (63.89 points). The study compares restrictive measures in India and Russia, analyses their impact on the spread of COVID-19; and estimates mortality rates. Besides, the study also probes population coverage aimed at diagnosing through the use of testing methods and possible economic consequences of quarantine measures

R&D and productivity in OECD firms and industries: A hierarchical meta-regression analysis

The relationship between R&D investment and firm/industry productivity has been investigated widely following seminal contributions by Zvi Griliches and others from late 1970s onwards. We aim to provide a systematic synthesis of the evidence, using 1253 estimates from 65 primary studies that adopt the so-called primal approach. In line with prior reviews, we report that the average elasticity and rate-of-return estimates are positive. In contrast to prior reviews, however, we report that: (i) the estimates are smaller and more heterogeneous than what has been reported before; (ii) residual heterogeneity remains high among firm-level estimates even after controlling for moderating factors; (iii) firm-level rates of return and within-industry social returns to R&D are small and do not differ significantly despite theoretical predictions of higher social returns; and (iv) the informational content of both elasticity and rate-of-return estimates needs to be interpreted cautiously. We conclude by highlighting the implications of these findings for future research and evidence-based policy

Variations in the effect of R&D investment on firm productivity: UK evidence

Our research provides novel findings about the heterogenous effects of R&D on UK firm-level productivity. In our comprehensive analysis, the effect of R&D on UK productivity is broken down by type of R&D, sources of R&D funding, sector and Pavitt class. Our sample consists of a panel of 10,920 firms from 1998 to 2012. We find that R&D has a positive and significant effect on labour productivity in the UK. However, there is considerable heterogeneity in the results. The output elasticity of R&D capital is higher for firms in less competitive sectors and in more R&D intensive sectors. Finally, we find that applied R&D, experimental R&D, intramural R&D and R&D from private sources tend to have higher productivity impacts compared with basic R&D, extramural R&D or publicly-funded R&D

Splitting fields and general differential Galois theory

An algebraic technique is presented that does not use results of model theory and makes it possible to construct a general Galois theory of arbitrary nonlinear systems of partial differential equations. The algebraic technique is based on the search for prime differential ideals of special form in tensor products of differential rings. The main results demonstrating the work of the technique obtained are the theorem on the constructedness of the differential closure and the general theorem on the Galois correspondence for normal extensions..Comment: 33 pages, this version coincides with the published on

Inverted-U relationship between innovation and survival: evidence from firm-level UK data

Theoretical and empirical work on innovation and firm survival has produced varied and often conflicting findings. In this paper, we draw on Schumpeterian models of competition and innovation and stochastic models of firm dynamics to demonstrate that the conflicting findings may be due to linear specifications of the innovation-survival relationship. We demonstrate that a quadratic specification is appropriate theoretically and fits the data well. Our findings from an unbalanced panel of 39,705 UK firms from 1997-2012 indicate that an inverted-U relationship holds for different types of R&D expenditures and sources of funding. We also report that R&D intensity is more likely to increase survival when firms are in more concentrated industries and in Pavitt technology classes consisting of specialized suppliers of technology and scale-intensive industries. Finally, we report that the effects of firm and industry characteristics as well as macroeconomic environment indicators are all consistent with prior findings. The results are robust to step-wise modeling, controlling for left truncation and use of lagged values to address potential simultaneity bias