Diffractive oblique plane microscopy

Imaging of neuronal activity with fluorescent indicators is an important technique in neuroscience. However, it remains challenging to record volumetric image data at fast frame rates and good resolution. One promising technique to achieve this goal is light sheet microscopy (LSM), but the right angle configuration of the excitation and imaging system limits its application. Oblique plane microscopy (OPM), a variant of LSM, circumvents this limitation by exciting oblique planes and detecting the image through the same microscope objective lens. So far, these techniques have relied on the use of high numerical aperture (NA) detection objective lenses, which limits their field of view. Here we present an OPM technique that allows for the use of low NA objective lenses by redirecting the light with the help of a diffraction grating. The microscope maintains a micrometer-scale lateral resolution over a large addressable imaging volume of 3.3×3.0×1.0  mm3. We demonstrate its practicality by imaging the whole brain of larval and juvenile zebrafish

Posthumous America

Posthumous America examines the literary idealization of a lost American past. It investigates the reasons why, for a group of French writers of the 18th and 19th centuries, America was never more potent as a driving ideal than in its loss. For example, Hoffmann examines the paradoxical American paradise depicted in Crèvecœur’s Lettres d’un cultivateur américain (1784); the “uchronotopia” of Lezay-Marnésia’s Lettres écrites des rives de l’Ohio (1800)—the imaginary perfect society set in America and based on what France might have become without the Revolution; and the political and nationalistic motivations behind Chateaubriand’s idealization of America in Voyage en Amérique (1827) and Mémoires d’outre-tombe (1850). From an historical perspective, Posthumous Americas works to determine when exactly these writers stopped transcribing what they actually observed in America and started giving imaginary accounts of their experiences

Posthumous America

Posthumous America examines the literary idealization of a lost American past. It investigates the reasons why, for a group of French writers of the 18th and 19th centuries, America was never more potent as a driving ideal than in its loss. For example, Hoffmann examines the paradoxical American paradise depicted in Crèvecœur’s Lettres d’un cultivateur américain (1784); the “uchronotopia” of Lezay-Marnésia’s Lettres écrites des rives de l’Ohio (1800)—the imaginary perfect society set in America and based on what France might have become without the Revolution; and the political and nationalistic motivations behind Chateaubriand’s idealization of America in Voyage en Amérique (1827) and Mémoires d’outre-tombe (1850). From an historical perspective, Posthumous Americas works to determine when exactly these writers stopped transcribing what they actually observed in America and started giving imaginary accounts of their experiences

Arrays and References in Resource Aware ML

This article introduces a technique to accurately perform static prediction of resource usage for ML-like functional programs with references and arrays. Previous research successfully integrated the potential method of amortized analysis with a standard type system to automatically derive parametric resource bounds. The analysis is naturally compositional and the resource consumption of functions can be abstracted using potential-annotated types. The soundness theorem of the analysis guarantees that the derived bounds are correct with respect to the resource usage defined by a cost semantics. Type inference can be efficiently automated using off-the-shelf LP solvers, even if the derived bounds are polynomials. However, side effects and aliasing of heap references make it notoriously difficult to derive bounds that depend on mutable structures, such as arrays and references. As a result, existing automatic amortized analysis systems for ML-like programs cannot derive bounds for programs whose resource consumption depends on data in such structures. This article extends the potential method to handle mutable structures with minimal changes to the type rules while preserving the stated advantages of amortized analysis. To do so, we introduce a swap operation for references and arrays that users can use to make programs suitable for automatic analysis. We prove the soundness of the analysis introducing a potential-annotated memory typing, which gathers all unique locations reachable from a reference. Apart from the design of the system, the main contribution is the proof of soundness for the extended analysis system

Hierarchical Cosmic Shear Power Spectrum Inference

We develop a Bayesian hierarchical modelling approach for cosmic shear power spectrum inference, jointly sampling from the posterior distribution of the cosmic shear field and its (tomographic) power spectra. Inference of the shear power spectrum is a powerful intermediate product for a cosmic shear analysis, since it requires very few model assumptions and can be used to perform inference on a wide range of cosmological models \emph{a posteriori} without loss of information. We show that joint posterior for the shear map and power spectrum can be sampled effectively by Gibbs sampling, iteratively drawing samples from the map and power spectrum, each conditional on the other. This approach neatly circumvents difficulties associated with complicated survey geometry and masks that plague frequentist power spectrum estimators, since the power spectrum inference provides prior information about the field in masked regions at every sampling step. We demonstrate this approach for inference of tomographic shear $E$-mode, $B$-mode and $EB$-cross power spectra from a simulated galaxy shear catalogue with a number of important features; galaxies distributed on the sky and in redshift with photometric redshift uncertainties, realistic random ellipticity noise for every galaxy and a complicated survey mask. The obtained posterior distributions for the tomographic power spectrum coefficients recover the underlying simulated power spectra for both $E$- and $B$-modes.Comment: 16 pages, 8 figures, accepted by MNRA