Marshall Hall, the reflex arc and epilepsy

Marshall Hall (1790-1857), who graduated from the University of Edinburgh's Medical School in 1812, was considered one of the greatest physiologists of his day. He advanced knowledge in various areas of medicine, in particular elucidating the mechanism of reflex activity in 1833. Hall suggested that convulsive epileptic seizures arose from heightened activity in the afferent limb or the central component of the reflex arc. From 1838 onwards he developed the idea that reflex-mediated neck muscle spasm in seizures obstructed cerebral venous return, congested the brain and thus caused unconsciousness. Associated reflex-mediated laryngeal spasm then caused convulsing. This was the most comprehensive physiologically based explanation of the major features of the convulsive epileptic seizure then available. Hall subsequently advocated and employed tracheotomy to prevent epileptic convulsing. His idea was taken up, modified and made more acceptable by others, and for a generation was the widely acknowledged basis for interpreting epileptogenesis. However, from 1870 onwards it was superseded by John Hughlings Jackson's accumulating evidence that epileptic seizures often arose in the cerebral cortex

Absinthe, epileptic seizures and Valentin Magnan

Absinthe is an alcoholic liquor containing extracts from the wormwood plant. It was widely consumed in France in the late nineteenth century. Its production was banned in 1915, partly because it was thought to cause neurological disturbances, including mental changes and epileptic seizures. Modern knowledge of an acceptable content of the convulsant alpha-thujone in absinthe has allowed the lifting of the production bans, and called into question the experimental work of Valentin Magnan in the 1870s, which formed the scientific background to the campaign against absinthe. An examination of Magnan's published investigations suggests that his science was very adequate by the standards of his time, and that he had shown that an alcohol-soluble component of wormwood did produce lapses of consciousness, myoclonic jerks and tonic-clonic convulsions in animals. Whether that component, presumably thujone, was present at convulsant concentrations in some of the available absinthes of Magnan's time cannot now be known

Hubert Airy, contemporary men of science and the migraine aura

Although there had been occasional references to the visual aura of migraine even in ancient medicine, little attention was given to the phenomenon until the first half of the nineteenth century when French authors began to describe it. In the medicine of English-speaking countries, apart from a few descriptions, it went largely unnoticed until the British Astronomer Royal, Sir George Airy, described his own experience of the visual aura in 1865. Five years later his son, Hubert Airy, also described his experience of it and that of a number of eminent contemporary men of science. The topic of the migraine aura was almost immediately taken up by two of the younger Airy's contemporaries and fellow Cambridge medical graduates, Peter Wallrock Latham and Edward Liveing, in their monographs. Subsequently, migraine with aura quickly became a well-recognised clinical entity in British medicine

Globular Cluster Systems in Brightest Cluster Galaxies. III: Beyond Bimodality

We present new deep photometry of the rich globular cluster (GC) systems around the Brightest Cluster Galaxies UGC 9799 (Abell 2052) and UGC 10143 (Abell 2147), obtained with the HST ACS and WFC3 cameras. For comparison, we also present new reductions of similar HST/ACS data for the Coma supergiants NGC 4874 and 4889. All four of these galaxies have huge cluster populations (to the radial limits of our data, comprising from 12000 to 23000 clusters per galaxy). The metallicity distribution functions (MDFs) of the GCs can still be matched by a bimodal-Gaussian form where the metal-rich and metal-poor modes are separated by ~0.8 dex, but the internal dispersions of each mode are so large that the total MDF becomes very broad and nearly continuous from [Fe/H] = -2.4 to Solar. There are, however, significant differences between galaxies in the relative numbers of \emph{metal-rich} clusters, suggesting that they underwent significantly different histories of mergers with massive, gas-rich halos. Lastly, the proportion of metal-poor GCs rises especially rapidly outside projected radii R > 4 R_eff, suggesting the importance of accreted dwarf satellites in the outer halo. Comprehensive models for the formation of GCs as part of the hierarchical formation of their parent galaxies will be needed to trace the systematic change in structure of the MDF with galaxy mass, from the distinctly bimodal form in smaller galaxies up to the broad continuum that we see in the very largest systems.Comment: In press for Astrophysical Journa

The light curve of a transient X-ray source

The Ariel-V satellite monitored the X-ray light curve of A1524-62 almost continuously from 40 days prior to maximum light until its disappearance below the effective experimental sensitivity. The source exhibited maximum light on approximately 4 December 1974, at a level of 0.9 the apparent magnitude of the Crab Nebula in the energy band 3-6 keV. Although similar to previously reported transient sources with a decay time constant of approximately 2 months, the source exhibited an extended, variable pre-flare on-state of about 1 month at a level of greater than approximately 0.1 maximum light. The four bright (greater than 0.2 of the Crab Nebula) transient sources observed during the first half-year of Ariel-V operation are indicative of a galactic disk distribution, and a luminosity at maximum in excess of 10 to the 37th power ergs/sec

The outcomes of pregnancy in women with untreated epilepsy

Purpose: To determine the outcomes in regards to seizure control and foetal malformation in pregnant women with epilepsy not treated with antiepileptic drugs (AEDs). Method: Analysis of data from the Australian Register of AEDs in Pregnancy on 148 women with epilepsy who were not receiving AEDs before and during at least the first trimester of pregnancy. Results: Seizure control was less likely to be maintained in AED-untreated pregnancies. Whether AED therapy had been ceased in preparation for pregnancy, or had not been employed for long periods before pregnancy, made no statistically significant difference to seizure control outcomes, but those who ceased therapy in preparation for pregnancy were more likely to again be taking AED therapy by term. Foetal malformation rates were reasonably similar in untreated pregnancies, and in treated pregnancies if pregnancies exposed to known AED teratogens (valproate and probably topiramate) were excluded from consideration. Conclusion: Leaving epilepsy untreated during pregnancy appears disadvantageous from the standpoint of seizure control: it also does not reduce the hazard of foetal malformation unless it avoids valproate or topiramate intake during pregnancy

Hierarchical Bayesian Inference of Globular Cluster Properties

We present a hierarchical Bayesian inference approach to estimating the structural properties and the phase space center of a globular cluster (GC) given the spatial and kinematic information of its stars based on lowered isothermal cluster models. As a first step towards more realistic modelling of GCs, we built a differentiable, accurate emulator of the lowered isothermal distribution function using interpolation. The reliable gradient information provided by the emulator allows the use of Hamiltonian Monte Carlo methods to sample large Bayesian models with hundreds of parameters, thereby enabling inference on hierarchical models. We explore the use of hierarchical Bayesian modelling to address several issues encountered in observations of GC including an unknown GC center, incomplete data, and measurement errors. Our approach not only avoids the common technique of radial binning but also incorporates the aforementioned uncertainties in a robust and statistically consistent way. Through demonstrating the reliability of our hierarchical Bayesian model on simulations, our work lays out the foundation for more realistic and complex modelling of real GC data.Comment: 16 pages, 12 figures, and 2 table

Improving Power Spectral Estimation using Multitapering: Precise asteroseismic modeling of stars, exoplanets, and beyond

Asteroseismic time-series data have imprints of stellar oscillation modes, whose detection and characterization through time-series analysis allows us to probe stellar interiors physics. Such analyses usually occur in the Fourier domain by computing the Lomb-Scargle (LS) periodogram, an estimator of the \textit{power spectrum} underlying unevenly-sampled time-series data. However, the LS periodogram suffers from the statistical problems of (1) inconsistency (or noise) and (2) bias due to high spectral leakage. In addition, it is designed to detect strictly periodic signals but is unsuitable for non-sinusoidal periodic or quasi-periodic signals. Here, we develop a multitaper spectral estimation method that tackles the inconsistency and bias problems of the LS periodogram. We combine this multitaper method with the Non-Uniform Fast Fourier Transform (\texttt{mtNUFFT}) to more precisely estimate the frequencies of asteroseismic signals that are non-sinusoidal periodic (e.g., exoplanet transits) or quasi-periodic (e.g., pressure modes). We illustrate this using a simulated and the Kepler-91 red giant light curve. Particularly, we detect the Kepler-91b exoplanet and precisely estimate its period, $6.246 \pm 0.002$ days, in the frequency domain using the multitaper F-test alone. We also integrate \texttt{mtNUFFT} into the \texttt{PBjam} package to obtain a Kepler-91 age estimate of $3.96 \pm 0.48$ Gyr. This $36$\% improvement in age precision relative to the $4.27 \pm 0.75$ Gyr APOKASC-2 (uncorrected) estimate illustrates that \texttt{mtNUFFT} has promising implications for Galactic archaeology, in addition to stellar interiors and exoplanet studies. Our frequency analysis method generally applies to time-domain astronomy and is implemented in the public Python package \texttt{tapify}, available at \url{https://github.com/aaryapatil/tapify}.Comment: 32 pages (3 pages in the Appendix), 14 figures, 2 tables, Submitted to A

C5AC_5^A axial form factor from bubble chamber experiments

A careful reanalysis of both Argonne National Laboratory and Brookhaven National Laboratory data for weak single pion production is done. We consider deuteron nuclear effects and normalization (flux) uncertainties in both experiments. We demonstrate that these two sets of data are in good agreement. For the dipole parametrization of $C_5^A(Q^2)$, we obtain $C_5^A(0)=1.19\pm 0.08$, $M_A=0.94\pm 0.03$ GeV. As an application we present the discussion of the uncertainty of the neutral current 1$\pi^0$ production cross section, important for the T2K neutrino oscillation experiment.Comment: 16 pages, 8 figures, 2 table