Diagnostic Doubt and Artificial Intelligence: An Inductive Field Study of Radiology Work

Technological developments in emerging AI technologies are assumed to further routinize and improve the efficiency of decision making tasks, even in professional contexts such as medical diagnosis, human resource management, and criminal justice. We have little research on how AI technologies are actually used and adopted in practice. Prior research on technology in organizations documents a gap between the expectations for new technology and its actual use in practice. We conducted a comparative field study of three sections in a Department of Radiology in a major US hospital, whereby new and existing AI tools were being used and experimented with. In contrast to expectations about AI tools, our study reveals how such tools can lead routine professional decision making tasks to become nonroutine, as they increased ambiguity and decision makers had to work to reduce it. This is particularly challenging since the costs of dealing with ambiguity – increased time to diagnose – were often weighed against the benefits of such ambiguity (potentially more accurate diagnoses). This study contributes to literatures related to technology, work, and organizations, as well as the role of ambiguity in professionals’ knowledge work

An Economy of Violence: Financial Crisis and Whig Constitutional Thought, 1720-1721

The South Sea bubble burst suddenly in September 1720, the second in a chain of panics that struck Paris, London, and Amsterdam in quick succession. The crash in London was by far the most severe; within weeks two-thirds of England\u27s nominal wealth had evaporated, public credit had collapsed, and London\u27s most distinguished banking houses tottered on the brink of ruin. Commerce ground to a halt, leaving a forest of half-built ships rotting in city harbors and a thicket of unfinished mansions in London\u27s fashionable districts

Geometric singular perturbation theory for stochastic differential equations

We consider slow-fast systems of differential equations, in which both the slow and fast variables are perturbed by noise. When the deterministic system admits a uniformly asymptotically stable slow manifold, we show that the sample paths of the stochastic system are concentrated in a neighbourhood of the slow manifold, which we construct explicitly. Depending on the dynamics of the reduced system, the results cover time spans which can be exponentially long in the noise intensity squared (that is, up to Kramers' time). We obtain exponentially small upper and lower bounds on the probability of exceptional paths. If the slow manifold contains bifurcation points, we show similar concentration properties for the fast variables corresponding to non-bifurcating modes. We also give conditions under which the system can be approximated by a lower-dimensional one, in which the fast variables contain only bifurcating modes.Comment: 43 pages. Published version. Remarks added, minor correction

Magnetoelliptic Instabilities

We consider the stability of a configuration consisting of a vertical magnetic field in a planar flow on elliptical streamlines in ideal hydromagnetics. In the absence of a magnetic field the elliptical flow is universally unstable (the ``elliptical instability''). We find this universal instability persists in the presence of magnetic fields of arbitrary strength, although the growthrate decreases somewhat. We also find further instabilities due to the presence of the magnetic field. One of these, a destabilization of Alfven waves, requires the magnetic parameter to exceed a certain critical value. A second, involving a mixing of hydrodynamic and magnetic modes, occurs for all magnetic-field strengths. These instabilities may be important in tidally distorted or otherwise elliptical disks. A disk of finite thickness is stable if the magnetic fieldstrength exceeds a critical value, similar to the fieldstrength which suppresses the magnetorotational instability.Comment: Accepted for publication in Astrophysical Journa

The pulsations and the dynamical stability of gaseous masses in uniform rotation

A variational principle, applicable to axisymmetric oscillations of uniformly rotating axisymmetric configurations, is established On the assumption that the Lagrangian displacement (describing the oscillation) at any point is normal to the level surface (of constant total potential) through that point, it is shown how the variational expression, for the frequencies of oscillation, can be reduced to simple quadratures. The reduction is explicitly carried out for certain stratifications of special interest. Some new results on the oscillations of slowly rotating configurations are included; and a number of related observations on their stability are also made

The equilibrium and the stability of the Jeans spheroids

The equilibrium and the stability of homogeneous masses distorted by the tidal effects of a secondary (of mass M' at a distance R) are re-examined on the basis of the second-order virial equations. In agreement with known results, it is shown that, under circumstances when the figure of equilibrium is a prolate spheroid, there is a maximum value of π( = GM'/R3) which is compatible with equilibrium. The problem of the small oscillations of these Jeans spheroids is next considered. The characteristic frequencies of oscillation belonging to the second harmonics are determined both in case the mass is considered incompressible and in case it is considered compressible and subject to the gas laws governing adiabatic changes. In the former case, instability sets in when μ attains its maximum value; and in the latter case it sets in before that happens