We present electron collision strengths and their thermally averaged values for the nebular forbidden lines of the astronomically abundant doubly ionized oxygen ion, O2+, in an intermediate coupling ...scheme using the Breit–Pauli relativistic terms as implemented in an R-matrix atomic scattering code. We use several atomic targets for the R-matrix scattering calculations including one with 72 atomic terms. We also compare with new results obtained using the intermediate coupling frame transformation method. We find spectroscopically significant differences against a recent Breit–Pauli calculation for the excitation of the O iii λ4363 transition but confirm the results of earlier calculations.
This article argues that existing theories of new and small firms fail to capture the temporal diversity of such enterprises. Most are ‘one-way bets’ because they provide an explanation only for ...growing firms. To address this, this article combines the role of chance with the optimism of the business owner into optimism and chance (OC) theory. This provides an insight into why, for example, very few new or small firms grow continuously and why, when compared to Europe, individuals in the USA who initially failed in business, ultimately became successful.
This paper links new firm survival with growth, with a focus on the patterns in firms' growth paths. We theorise a Gambler's Ruin framework by arguing that new firm performance is best modelled as a ...random walk process, but that survival is nonrandom and depends primarily on the stock of accumulated resources. A firm's resources are either there when the business begins or are generated by successful periods — ‘wins’. The empirical section tracks, over six years, the sales and survival/non-survival of 6247 UK start-ups which all began trading in the same quarter of 2004. We do not find strong evidence in favour of a taxonomy of growth paths, because we observe that every possible growth path seems to occur with roughly equal probability. However, we observe that growth paths influence subsequent survival. Controlling for lagged size, we observe that longer lags of growth, and even start-up size, have significant effects on survival.
► We investigate the growth and survival of nascent businesses by analyzing their bank records. ► We do not find strong evidence in favour of a taxonomy of growth paths. ► Every possible growth path seems to occur with roughly equal probability. ► We observe that survival depends on the business' growth path. ► Even when controlling for lagged size, lagged growth has significant effects on survival.
Cuprate superconductors have long been known to exhibit an energy gap that persists high above the superconducting transition temperature (\({T}_{{\rm{c}}}\)). Debate has continued now for decades as ...to whether it is a precursor superconducting gap or a pseudogap arising from some competing correlation. Failure to resolve this has arguably delayed explaining the origins of superconductivity in these highly complex materials. Here we effectively settle the question by calculating a variety of thermodynamic and spectroscopic properties, exploring the effect of a temperature-dependent pair-breaking term in the self-energy in the presence of pairing interactions that persist well above \({T}_{{\rm{c}}}\). We start by fitting the detailed temperature-dependence of the electronic specific heat and immediately can explain its hitherto puzzling field dependence. Taking this same combination of pairing temperature and pair-breaking scattering we are then able to simultaneously describe in detail the unusual temperature and field dependence of the superfluid density, tunneling, Raman and optical spectra, which otherwise defy explanation in terms a superconducting gap that closes conventionally at \({T}_{{\rm{c}}}\). These findings demonstrate that the gap above \({T}_{{\rm{c}}}\) in the overdoped regime likely originates from incoherent superconducting correlations, and is distinct from the competing-order ‘pseudogap’ that appears at lower doping.
ABSTRACT
We present the results of several collisional-radiative models describing optically thin emissivities of the main lines in neutral helium formed by recombination, for a grid of electron ...temperatures and densities, typical of H ii regions and planetary nebulae. Accurate emissivities are required for example to measure the helium abundance in nebulae and as a consequence its primordial value. We compare our results with those obtained by previous models, finding significant differences, well above the target accuracy of 1 per cent. We discuss in some detail our chosen set of atomic rates and the differences with those adopted by previous models. The main differences lie in the treatment of electron and proton collision rates and we discuss which transitions are least sensitive to the choice of these rates and therefore best suited to high-precision abundance determinations. We have focused our comparisons on the case B approximation where only He and He+ are considered, but also present results of full models including the bare nuclei, photoexcitation, and photoionization, and either black-body or observed illuminating spectrum in the case of the Orion nebula, to indicate which spectral lines are affected by opacity. For those transitions, accurate radiative transfer calculations should be performed. We provide tables of emissivities for all transitions within n ≤ 5 and all those between the n ≤ 5 and n′ ≤ 25 states, in the log Te (K) = 103.0(0.1)4.6 and log Ne (cm−3) = 102(0.5)6 ranges, and a fortran code to interpolate to any Te, Ne within these ranges.
How social norms are formed likely has a bearing on the mechanisms underlying their effects on behavioral outcomes. We propose three mechanisms of norms formation - through direct experience, ...symbolically through media, or imaginatively - and introduce ideas about normative durability, normative subscription, normative volume, personal agency, and polarization of norms - that likely have a bearing on how norms affect behaviors. The COVID-19 pandemic has important implications for how norms are formed, which in turn invoke different underlying mechanisms in the relationship between social norms and behaviors. We propose a number of hypotheses for future studies to test.
This paper proposes an improved strategy for the optimization of dynamic photovoltaic arrays (DPVAs) utilizing the "irradiance equalization" (IEq) reconfiguration strategy. This type of ...reconfigurable array is already very robust as it amalgamates the flexibility of dynamic reconfiguration with the averaging ability of total cross-tied array architecture. This paper identifies four areas to further increase the power yield and significantly reduce the time for a return on investment. Results indicate potential efficiency improvements of more than 10% in some cases, and between 4% and 10% across a number of random and abrupt shading conditions. As in any DPVA system, the proposed approaches require additional hardware and advanced control algorithms compared to a static PV array, but anyone implementing a dynamic array has already committed themselves to including the majority of this infrastructure. This investigation supports the idea of a fully dynamic IEq-DPVA with the ability to resize its array dimensions while implementing a rapid sorting algorithm based on information gathered using a novel precision irradiance profiling technique.
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