Seizures are a disruption of normal brain activity present across a vast range of species and conditions. We introduce an organizing principle that leads to the first objective Taxonomy of Seizure Dynamics (TSD) based on bifurcation theory. The ‘dynamotype’ of a seizure is the dynamic composition that defines its observable characteristics, including how it starts, evolves and ends. Analyzing over 2000 focal-onset seizures from multiple centers, we find evidence of all 16 dynamotypes predicted in TSD. We demonstrate that patients’ dynamotypes evolve during their lifetime and display complex but systematic variations including hierarchy (certain types are more common), non-bijectivity (a patient may display multiple types) and pairing preference (multiple types may occur during one seizure). TSD provides a way to stratify patients in complement to present clinical classifications, a language to describe the most critical features of seizure dynamics, and a framework to guide future research focused on dynamical properties.

30Seizures are a disruption of normal brain activity present across a vast range of species, diseases, 31 and conditions. Here we introduce a mathematical theory, Epidynamics, which provides a 32 conceptual framework to characterize how seizures start, evolve, and terminate. We provide the 33 first objective taxonomy of seizures based on a straightforward analysis of EEG data. Analyzing 34 over 2000 focal-onset seizures recorded from 7 epilepsy centers on five continents, we find 35 evidence of the predicted 16 Dynamic Classes of seizures. The theory also enables drawing a 36 map of brain dynamics that includes most seizure classes and status epilepticus. We demonstrate 37 that patients navigate the map during their lifetime and verify critical predictions of the theory. 38Epidynamics not only provides a way to stratify patients in complement to present practical 39 classifications but also guides biophysically based mechanistic approaches and provides a 40 language to describe the most critical features of seizure dynamics. 41 42 Impact statement: 43Epidynamics, a mathematically-derived method of classifying seizure dynamics, provides a 44 rigorous method for classifying and quantifying seizures and a theoretical framework for 45 understanding seizure initiation and propagation.

Volatile organic compounds (VOCs) play a crucial role in cider quality. Many variables involved in the fermentation process contribute to cider fragrance, but their relative impact on the finished odor remains ambiguous, because there is little consensus on the most efficient method for cider volatile analysis. Herein, we have optimized and applied a headspace solid phase microextraction gas chromatography–mass spectrometry (HS-SPME GC-MS) method for the chemical analysis of cider VOCs. We determined that the 30 min exposure of a divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) solid phase microextraction (SPME) fiber at 40 °C yielded detection of the widest variety of VOCs at an extraction efficiency >49% higher than comparable fibers. As a proof-of-concept experiment, we utilized this method to profile cider aroma development throughout the fermentation process for the first time. The results yielded a very practical outcome for cider makers: a pre-screening method for determining cider quality through the detection of off-flavors early in the fermentation process. The aroma profile was found to be well established 72 h after fermentation commenced, with major esters varying by 18.6% ± 4.1% thereafter and higher alcohols varying by just 12.3% ± 2.6%. Lastly, we analyzed four mature ciders that were identically prepared, save for the yeast strain. Twenty-seven key VOCs were identified, off-flavors (4-ethylphenol and 4-ethyl-2-methoxyphenol) were detected, and odorants were quantified at desirable concentrations when compared to perception thresholds. VOCs varied considerably following fermentation with four novel strains of S. cerevisiae, evidencing the central importance of yeast strain to the finished cider aroma.