What is the nature of the distinction between events and processes?

A distinction of ontological category is often drawn between events and process, analogous to the distinction between particular spatial things and the matter from which they’re made. The traditional arguments for the distinction arise from observations of the aspectual differences of verbs – e.g. ‘pushed’ and ‘pushing’ – made by Zeno Vendler and Anthony Kenny and then developed by Alexander Mourelatos. Mourelatos identifies a difference of apparent quantification in the nominalisations of sentences with aspectual differences of their verbs: ‘Jones pushed the cart to the top of the hill’ transforms to ‘there was a pushing of the cart to the top of the hill by Jones’ – a count-quantified sentence, whereas ‘Jones pushed the cart for hours’ transforms to ‘there was pushing of the cart for hours by Jones’ – a mass-quantified sentence. Mourelatos then takes these apparent differences to be metaphysically perspicuous, revealing a categorical distinction between events and process, where process is understood as the stuff of time. Rowland Stout offers a different articulation of the distinction, arguing that it is a distinction between events and processes, i.e. a distinction between two categories of particular. I argue that both proposals have their merit; Mourelatos is right to treat process as the stuff of time, and Stout is right to recognise individual processes. Drawing on Thomas Crowther’s work, who suggests that what is salient to the distinction are matters of form and differences in restrictiveness of boundaries, I go on to present an understanding of individual processes as dynamic, growing entities, and defend the position that recognises events and processes as belonging to distinct metaphysical categories. Kathleen Gill has levelled objections to the recognition of such a distinction, claiming that there are few grounds for regarding the distinction as genuinely metaphysical, and suggested instead that it is better understood as artifactual. I explore the notion of an artefact in relation to events and processes, and show that while the distinction does appear to be artifactual in the restricted realm of agent activity and action, it is not plausible to regard it as artifactual outside of this realm. I articulate the distinction between events and processes as one of a difference between completing and finishing, where completing is understood as coming to exemplify a sortal

Spatio-temporal bivariate statistical models for atmospheric trace-gas inversion

Atmospheric trace-gas inversion refers to any technique used to predict spatial and temporal fluxes using mole-fraction measurements and atmospheric simulations obtained from computer models. Studies to date are most often of a data-assimilation flavour, which implicitly consider univariate statistical models with the flux as the variate of interest. This univariate approach typically assumes that the flux field is either a spatially correlated Gaussian process or a spatially uncorrelated non-Gaussian process with prior expectation fixed using flux inventories (e.g., NAEI or EDGAR in Europe). Here, we extend this approach in three ways. First, we develop a bivariate model for the mole-fraction field and the flux field. The bivariate approach allows optimal prediction of both the flux field and the mole-fraction field, and it leads to significant computational savings over the univariate approach. Second, we employ a lognormal spatial process for the flux field that captures both the lognormal characteristics of the flux field (when appropriate) and its spatial dependence. Third, we propose a new, geostatistical approach to incorporate the flux inventories in our updates, such that the posterior spatial distribution of the flux field is predominantly data-driven. The approach is illustrated on a case study of methane (CH$_4$) emissions in the United Kingdom and Ireland.Comment: 39 pages, 8 figure

Anodic formation and characterization of nanoporous InP in aqueous KOH electrolytes

The anodic behavior of highly doped (> 1018 cm-3) n-InP in aqueous KOH was investigated. Electrodes anodized in the absence of light in 2- 5 mol dm-3 KOH at a constant potential of 0.5- 0.75 V (SCE), or subjected to linear potential sweeps to potentials in this range, were shown to exhibit the formation of a nanoporous subsurface region. Both linear sweep voltammograms and current-time curves at constant potential showed a characteristic anodic peak, corresponding to formation of the nanoporous region. No porous region was formed during anodization in 1 mol dm-3 KOH. The nanoporous region was examined using transmission electron microscopy and found to have a thickness of some 1- 3 μm depending on the anodization conditions and to be located beneath a thin (typically ∼40 nm), dense, near-surface layer. The pores varied in width from 25 to 75 nm and both the pore width and porous region thickness were found to decrease with increasing KOH concentration. The porosity was approximately 35%. The porous layer structure is shown to form by the localized penetration of surface pits into the InP, and the dense, near-surface layer is consistent with the effect of electron depletion at the surface of the semiconductor

Topological and nontopological degeneracies in generalized string-net models

Generalized string-net models have been proposed recently in order to enlarge the set of possible topological quantum phases emerging from the original string-net construction. In the present work we do not consider vertex excitations, and we restrict ourselves to plaquette excitations, or fluxons, that satisfy important identities. We explain how to compute the energy-level degeneracies of the generalized string-net Hamiltonian associated with an arbitrary unitary fusion category. In contrast to the degeneracy of the ground state, which is purely topological, the degeneracy of excited energy levels depends not only on the Drinfeld center of the category, but also on internal multiplicities obtained from the tube algebra defined from the category. For a noncommutative category, these internal multiplicities result in extra nontopological degeneracies. Our results are valid for any trivalent graph and any orientable surface. We illustrate our findings with nontrivial examples

Formation of nanoporous InP by electrochemical anodization

Porous InP layers can be formed electrochemically on (100) oriented n- InP substrates in aqueous KOH. A nanoporous layer is obtained underneath a dense near-surface layer and the pores appear to propagate from holes through the near-surface layer. In the early stages of the anodization transmission electron microscopy (TEM) clearly shows individual porous domains which appear to have a square-based pyramidal shape. Each domain appears to develop from an individual surface pit which forms a channel through this near-surface layer. We suggest that the pyramidal structure arises as a result of preferential pore propagation along the directions. AFM measurements show that the density of surface pits increases with time. Each of these pits acts as a source for a pyramidal porous domain. When the domains grow, the current density increases correspondingly. Eventually, the domains meet forming a continuous porous layer, the interface between the porous and bulk InP becomes relatively flat and its total effective surface area decreases resulting in a decrease in the current density. Numerical models of this process have been developed. Current-time curves at constant potential exhibit a peak and porous layers are observed to form beneath the electrode surface. The density of pits formed on the surface increases with time and approaches a plateau value

Pitting and porous layer formation on n-InP anodes

Surface pitting occurs when InP electrodes are anodized in KOH electrolytes at concentrations in the range 2 - 5 mol dm-3. The process has been investigated using atomic force microscopy (AFM) and the results correlated with cross-sectional transmission electron microscopy (TEM) and electroanalytical measurements. AFM measurements show that pitting of the surface occurs and the density of pits is observed to increase with time under both potentiodynamic and potentiostatic conditions. This indicates a progressive pit nucleation process and implies that the development of porous domains beneath the surface is also progressive in nature. Evidence for this is seen in plan view TEM images in which individual domains are seen to be at different stages of development. Analysis of the cyclic voltammograms of InP electrodes in 5 mol dm-3 KOH indicates that, above a critical potential for pit formation, the anodic current is predominantly time dependent and there is little differential dependence of the current on potential. Thus, pores continue to grow with time when the potential is high enough to maintain depletion layer breakdown conditions

A mechanistic study of anodic formation of porous InP

When porous InP is anodically formed in KOH electrolytes, a thin layer ~40 nm in thickness, close to the surface, appears to be unmodified. We have investigated the earlier stages of the anodic formation of porous InP in 5 mol dm-3 KOH. TEM clearly shows individual porous domains which appear triangular in cross-section and square in plan view. The crosssections also show that the domains are separated from the surface by a ~40 nm thick, dense InP layer. It is concluded that the porous domains have a square-based pyramidal shape and that each one develops from an individual surface pit which forms a channel through this near-surface layer. We suggest that the pyramidal structure arises as a result of preferential pore propagation along the directions. AFM measurements show that the density of surface pits increases with time. Each of these pits acts as a source for a pyramidal porous domain, and these domains eventually form a continuous porous layer. This implies that the development of porous domains beneath the surface is also progressive in nature. Evidence for this was seen in plan view TEM images. Merging of domains continues to occur at potentials more anodic than the peak potential, where the current is observed to decrease. When the domains grow, the current density increases correspondingly. Eventually, domains meet, the interface between the porous and bulk InP becomes relatively flat and its total effective surface area decreases resulting in a decrease in the current density. Quantitative models of this process are being developed

Photochemical Pump and NMR Probe to monitor the formation and kinetics of hyperpolarized metal dihydrides

On reaction of IrI(CO)(PPh 3) 21with para-hydrogen(p-H 2),Ir(H) 2I(CO)(PPh 3) 22 is formed which exhibits strongly enhanced 1H NMR signals for its hydride resonances. Complex 2 also shows similar enhancement of its NMR spectra when it is irradiated under p-H 2. We report the use of this photochemical reactivity to measure the kinetics of H 2 addition by laser-synchronized reactions in conjunction with NMR. The single laser pulse promotes the reductive elimination of H 2 from Ir(H) 2I(CO)(PPh 3) 22 in C 6D 6 solution to form the 16-electron precursor 1, back reaction with p-H 2 then reforms 2 in a well-defined nuclear spin-state. The build up of this product can be followed by incrementing a precisely controlled delay (τ), in millisecond steps, between the laser and the NMR pulse. The resulting signal vs. time profile shows a dependence on p-H 2 pressure. The plot of k obs against p-H 2 pressure is linear and yields the second order rate constant, k 2, for H 2 addition to 1 of (3.26 ± 0.42) × 10 2 M −1 s −1. Validation was achieved by transient-UV-vis absorption spectroscopy which gives k 2 of (3.06 ± 0.40) × 10 2 M −1 s −1. Furthermore, irradiation of a C 6D 6 solution of 2 with multiple laser shots, in conjunction with p-H 2 derived hyperpolarization, allows the detection and characterisation of two minor reaction products, 2a and 3, which are produced in such low yields that they are not detected without hyperpolarization. Complex 2a is a configurational isomer of 2, while 3 is formed by substitution of CO by PPh

Nanoporous domains in n-InP anodized in KOH

A model of porous structure growth in semiconductors based on propagation of pores along the A directions has been developed. The model predicts that pores originating at a surface pit lead to porous domains with a truncated tetrahedral shape. SEM and TEM were used to examine cross- sections of n-InP electrodes in the early stages of anodization in aqueous KOH and showed that pores propagate along the A directions. Domain outlines observed in both TEM and SEM images are in excellent agreement with the model. The model is further supported by plan-view TEM and surface SEM images. Quantitative measurements of aspect ratios of the observed domains are in excellent agreement with the predicted values