Of Bayes and bullets: An embodied, situated, targeting-based account of predictive processing

Here I argue that Jakob Hohwy’s (Hohwy 2013) cognitivist interpretation of predictive processing (a) does not necessarily follow from the evidence for the importance of Bayesian processing in the brain; (b) is rooted in a misunderstanding of our epistemic position in the world; and (c) is undesirable in that it leads to epistemic internalism or idealism. My claim is that the internalist/idealist conclusions do not follow from predictive processing itself, but instead from the model of perception Hohwy’s adopts, and that there are alternate models of perception that do not lend themselves to idealist conclusions. The position I advocate is similar to Andy Clark’s embodied/embedded interpretation of Bayesian processing (Clark 2015); however, I argue that Clark’s position, as currently stated, also potentially leads to idealist conclusions. I offer a specific emendation to Clark’s view that I believe avoids this pitfall

Output from Bose condensates in tunnel arrays: the role of mean-field interactions and of transverse confinement

We present numerical studies of atomic transport in 3D and 1D models for a mode-locked, pulsed atom laser as realized by Anderson and Kasevich [Science 281 (1998) 1686] using an elongated Bose condensate of ${}^{87}$Rb atoms poured into a vertical optical lattice. From our 3D results we ascertain in a quantitative manner the role of mean-field interactions in determining the shape and the size of the pulses in the case of Gaussian transverse confinement. By comparison with 1D simulations we single out a best-performing 1D reduction of the mean-field interactions, which yields quantitatively useful predictions for all main features of the matter output.Comment: 12 pages, 2 figure

Methods for Cancer Detection

A method is provided for detecting an analyte indicative of a cancer or a metastatic disease condition, which utilizes the ability of the analyte to induce permeability in a barrier. The method includes providing a biosensor having a barrier which is substantially impermeable to an ion, a permeable membrane which is selective for the ion, and a detector capable of detecting the ion. The biosensor is contacted with a sample including at least one of the ion and the analyte, wherein the analyte causes at least a portion of the ion to pass through the barrier and the membrane. Passage of the ion through the barrier and membrane allows detection of the ion, providing indirect detection of the analyte. In one embodiment, the barrier is a cell monolayer, the membrane is selective for potassium, and the analyte is vascular endothelial cell growth factor

1D model for the dynamics and expansion of elongated Bose-Einstein condensates

We present a 1D effective model for the evolution of a cigar-shaped Bose-Einstein condensate in time dependent potentials whose radial component is harmonic. We apply this model to investigate the dynamics and expansion of condensates in 1D optical lattices, by comparing our predictions with recent experimental data and theoretical results. We also discuss negative-mass effects which could be probed during the expansion of a condensate moving in an optical lattice.Comment: RevTeX4, 8 pages, 10 figures, extended and revised versio

Probing the energy bands of a Bose-Einstein condensate in an optical lattice

We simulate three experimental methods which could be realized in the laboratory to probe the band excitation energies and the momentum distribution of a Bose-Einstein condensate inside an optical lattice. The values of the excitation energies obtained in these different methods agree within the accuracy of the simulation. The meaning of the results in terms of density and phase deformations is tested by studying the relaxation of a phase-modulated condensate towards the ground state.Comment: 5 pages, 5 figure

Raman spectroscopy insights into the a- and d-phases of formamidinium lead iodide (FAPbI3)

Solar perovskites have received phenomenal attention and success over the past decade, due to their high power conversion efficiencies (PCE), ease of fabrication and low cost which has enabled the prospect of them being a real commercial contender to the traditional silicon technology. In one of the several developments on the archetypal MAPbI3perovskite absorber layer, FAPbI3was found to obtain a higher PCE, likely due to its more optimum band gap, with doping strategies focusing on the inclusion of MA+/Cs+cations to avoid the unfavourable phase transformation to a photoinactive phase. To better understand the phase change from the photoactive cubic (Pm3¯m) black (a) phase to the unwanted photoinactive (P63/mmc) yellow (d) phase, we make use of variable temperature Raman spectroscopy to probe the molecular species and its relationship to the inorganic framework. We show for the first time there to be no Raman active modes for the a phase up to 4000 cm-1, which can be correlated to thePm3¯mcubic symmetry of that phase. Our detailed studies suggest that previous reports of the observation of Raman peaks for this phase are likely associated with degradation reactions from the localised laser exposure and the formation of Raman active lead oxide. In addition, we have identified water as a contributing factor to the transformation, and observed a corresponding signal in the Raman spectra, although confirmation of its exact role still remains inconclusive

Black holes as mirrors: quantum information in random subsystems

We study information retrieval from evaporating black holes, assuming that the internal dynamics of a black hole is unitary and rapidly mixing, and assuming that the retriever has unlimited control over the emitted Hawking radiation. If the evaporation of the black hole has already proceeded past the "half-way" point, where half of the initial entropy has been radiated away, then additional quantum information deposited in the black hole is revealed in the Hawking radiation very rapidly. Information deposited prior to the half-way point remains concealed until the half-way point, and then emerges quickly. These conclusions hold because typical local quantum circuits are efficient encoders for quantum error-correcting codes that nearly achieve the capacity of the quantum erasure channel. Our estimate of a black hole's information retention time, based on speculative dynamical assumptions, is just barely compatible with the black hole complementarity hypothesis.Comment: 18 pages, 2 figures. (v2): discussion of decoding complexity clarifie

Moderate deviations for the determinant of Wigner matrices

We establish a moderate deviations principle (MDP) for the log-determinant $\log | \det (M_n) |$ of a Wigner matrix $M_n$ matching four moments with either the GUE or GOE ensemble. Further we establish Cram\'er--type moderate deviations and Berry-Esseen bounds for the log-determinant for the GUE and GOE ensembles as well as for non-symmetric and non-Hermitian Gaussian random matrices (Ginibre ensembles), respectively.Comment: 20 pages, one missing reference added; Limit Theorems in Probability, Statistics and Number Theory, Springer Proceedings in Mathematics and Statistics, 201

A low-voltage retarding-field Mott polarimeter for photocathode characterization

Nuclear physics experiments at Thomas Jefferson National Accelerator Facility's CEBAF rely on high polarization electron beams. We describe a recently commissioned system for prequalifying and studying photocathodes for CEBAF with a load-locked, low-voltage polarized electron source coupled to a compact retarding-field Mott polarimeter. The polarimeter uses simplified electrode structures and operates from 5 to 30 kV. The effective Sherman function for this device has been calibrated by comparison with the CEBAF 5 MeV Mott polarimeter. For elastic scattering from a thick gold target at 20 keV, the effective Sherman function is 0.201(5). Its maximum efficiency at 20 keV, defined as the detected count rate divided by the incident particle current, is 5.4(2) x 10-4, yielding a figure-of-merit, or analyzing power squared times efficiency, of 1.0(1) x 10-5. The operating parameters of this new polarimeter design are compared to previously published data for other compact Mott polarimeters of the retarding-field type.Comment: 9 figure