On the Matter of Robot Minds

The view that phenomenally conscious robots are on the horizon often rests on a certain philosophical view about consciousness, one we call “nomological behaviorism.” The view entails that, as a matter of nomological necessity, if a robot had exactly the same patterns of dispositions to peripheral behavior as a phenomenally conscious being, then the robot would be phenomenally conscious; indeed it would have all and only the states of phenomenal consciousness that the phenomenally conscious being in question has. We experimentally investigate whether the folk think that certain (hypothetical) robots made of silicon and steel would have the same conscious states as certain familiar biological beings with the same patterns of dispositions to peripheral behavior as the robots. Our findings provide evidence that the folk largely reject the view that silicon-based robots would have the sensations that they, the folk, attribute to the biological beings in question

THE YEAR 2000: A FOOD INDUSTRY FORECAST

Agribusiness,

On the periodicity of oscillatory reconnection

Context. Oscillatory reconnection is a time-dependent magnetic reconnection mechanism that naturally produces periodic outputs from aperiodic drivers. Aims. This paper aims to quantify and measure the periodic nature of oscillatory reconnection for the first time. Methods. We solve the compressible, resistive, nonlinear magnetohydrodynamics (MHD) equations using 2.5D numerical simulations. Results. We identify two distinct periodic regimes: the impulsive and stationary phases. In the impulsive phase, we find the greater the amplitude of the initial velocity driver, the longer the resultant current sheet and the earlier its formation. In the stationary phase, we find that the oscillations are exponentially decaying and for driving amplitudes 6.3−126.2 kms−1, we measure stationary-phase periods in the range 56.3−78.9 s, i.e. these are high frequency (0.01−0.02 Hz) oscillations. In both phases, we find that the greater the amplitude of the initial velocity driver, the shorter the resultant period, but note that different physical processes and periods are associated with both phases. Conclusions. We conclude that the oscillatory reconnection mechanism behaves akin to a damped harmonic oscillator

Energy spectra comparisons for matched clinical electron beams on Elekta linear accelerators using a permanent magnet spectrometer

Purpose: The purpose of this work was to use a permanent magnet electron energy spectrometer to measure and compare electron beam energy spectra from matched electron beams on Elekta radiotherapy accelerators at Mary Bird Perkins Cancer Center Methods: Electron beamcollimation, X-ray background collimation, and irradiation geometry were developed to produce suitable latent images in computed radiography (CR) strips at the exit side of a 0.5-Tesla permanent magnet spectrometer.An analytical technique transformed CR strip images into energy spectra on central axis at 95-cm source-to-collimator distance.Electron energy spectra at 7, 9, 10, 11, 13, 16, and 20 MeV for four accelerators, whose beams had been matched to one of two reference accelerators at commissioning, were measured and compared to measured energy spectra of their reference accelerator.Percent depth-dose (%DD) matching criteria of 0.05 cm for R50 and 0.1 cm for R80-20correlated to 0.12 MeV and 2.0 MeV for the modified incident peak mean energy (PME) and full-width-at-half-maximum (FWHM) of the energy spectra, respectively. Results: For 19 of the 28 matched beams, PME did not match PME of their reference accelerator to within 0.12 MeV, showing shifts likely due to inadequate beam tuning subsequent to commissioning and energy drifting of the accelerator within quality assurance (QA) limits ± 0.2cm of R50).However, FWHM of all 28 matched beams matched FWHM of their reference accelerator despite having considerably different spectral shapes.By correlating %DD metrics with energy spectra metrics, it was determined that R50 had a linear relationship with PME, whereas R80-20depended primarily on PME and secondarily on FWHM. Conclusions: First, this study demonstrated that not all MBPCC electron beam energy spectra were matched.Second, electron beams with matched %DD metrics do not necessarily have matched energy spectra, which are more sensitive for comparing beams than %DD curves.Third, the instrument, methods, and analytical analysis developed in this study offer the potential for an inexpensive, lightweight, real-time electron energy spectrometer which could be useful for beam tuning and matching, QA, and determination of X-ray and electron beam energy spectra for radiation transport calculations

Non-symmetric magnetohydrostatic equilibria:a multigrid approach

Aims. Linear magnetohydrostatic (MHS) models of solar magnetic fields balance plasma pressure gradients, gravity and Lorentz forces where the current density is composed of a linear force-free component and a cross-field component that depends on gravitational stratification. In this paper, we investigate an efficient numerical procedure for calculating such equilibria.Methods. The MHS equations are reduced to two scalar elliptic equations – one on the lower boundary and the other within the interior of the computational domain. The normal component of the magnetic field is prescribed on the lower boundary and a multigrid method is applied on both this boundary and within the domain to find the poloidal scalar potential. Once solved to a desired accuracy, the magnetic field, plasma pressure and density are found using a finite difference method.Results. We investigate the effects of the cross-field currents on the linear MHS equilibria. Force-free and non-force-free examples are given to demonstrate the numerical scheme and an analysis of speed-up due to parallelization on a graphics processing unit (GPU) is presented. It is shown that speed-ups of ×30 are readily achievable

Quantitative Precipitation Estimation with Distributed Radar Networks

This talk describes our efforts to realize a network of small, low-cost X-band radars suitable for deployment in high-population urban regions. The radar design is based on a single-polarization Raymarine boat radar suitably modified to suppress clutter and deal with the vertical variation in rainfall intensity