Acceleration of Boltzmann Collision Integral Calculation Using Machine Learning

The Boltzmann equation is essential to the accurate modeling of rarefied gases. Unfortunately, traditional numerical solvers for this equation are too computationally expensive for many practical applications. With modern interest in hypersonic flight and plasma flows, to which the Boltzmann equation is relevant, there would be immediate value in an efficient simulation method. The collision integral component of the equation is the main contributor of the large complexity. A plethora of new mathematical and numerical approaches have been proposed in an effort to reduce the computational cost of solving the Boltzmann collision integral, yet it still remains prohibitively expensive for large problems. This paper aims to accelerate the computation of this integral via machine learning methods. In particular, we build a deep convolutional neural network to encode/decode the solution vector, and enforce conservation laws during post-processing of the collision integral before each time-step. Our preliminary results for the spatially homogeneous Boltzmann equation show a drastic reduction of computational cost. Specifically, our algorithm requires O(n3) operations, while asymptotically converging direct discretization algorithms require O(n6), where n is the number of discrete velocity points in one velocity dimension. Our method demonstrated a speed up of 270 times compared to these methods while still maintaining reasonable accuracy

Systems Evolutionary Biology of Waddington’s Canalization and Genetic Assimilation

In recent years, there has been growing interest in computer modeling of the evolution of gene and cell regulatory networks, in general, and in computational studies of the classic ideas of Baldwin, Schmalhausen, Waddington, and followers, in particular. Two related aspects of Waddington’s evolutionary theories are the concepts of canalization and of genetic assimilation. Canalization is associated with the robust development of an individual to diverse perturbations and noise, though, when fluctuations in developmental factors exceed a particular limit, the normal developmental trajectory can be “thrown out” of the robust canal, resulting in an altered phenotype. If selective pressure favors the new phenotype, an initial individual loss of canalization can lead to phenotypic changes in the population (with canalization then becoming established for the new phenotype). Genetic assimilation is the subsequent genetic fixing of the new trait in the population. Recent experimental and theoretical works have established a quantitative basis for these classic concepts of Waddington; this chapter will review these new developments in systems evolutionary biology

« Adorno au milieu de la jungle Lacandon »

Dans ton livre Change the World without taking Power – dont nous avons publié un extrait dans le dernier numéro de Variations – tu fais référence à la Théorie critique allemande. Selon toi, pourquoi est-il important de lire Adorno aujourd’hui ? Ce en quoi la Théorie critique m’importe en général ? La raison en est que je pense le problème politique et pratique actuel à travers la négation-création, cette problématique qui distingue les auteurs de la Théorie critique. Si le point de départ ne ..

From Scientific Discovery to Cures: Bright Stars within a Galaxy

We propose that data mining and network analysis utilizing public databases can identify and quantify relationships between scientific discoveries and major advances in medicine (cures). Further development of such approaches could help to increase public understanding and governmental support for life science research and could enhance decision making in the quest for cures

Reviewing the evidence base : Attraction, pathways and retention : A focus on attracting candidates

[Extract] Key points for orienting readers 1. Induction and mentor programs are beneficial for early career teachers. 2. Close alignment between academic training and practice is crucial for preparing teachers to be effective and satisfied. 3. Positive and supportive school culture is one of the main factors associated with retention. 4. Supportive leadership is crucial for retention. 5. Equity: Schools with higher equity needs are more likely to face higher teacher turnover

Student sensor lab at home: safe repurposing of your gadgets

The COVID-19 pandemic imposed various restrictions on the accessibility of conventional teaching laboratories. Enabling learning and experimenting at home became necessary to support the practical element of students’ learning. Unfortunately, it is not viable to provide or share a fully featured sensor lab to every student because of the prohibitive costs involved. Therefore, repurposing electronic devices that are common to students can bring about the sought-after practical learning experience without the hefty price tag. In distinction to the conventional lab instruments though, consumer grade devices are not designed for use with external sensors and/or electronic circuitry. They are not professionally maintained, do not undergo periodic safety tests and are not calibrated. Nevertheless, nearly all modern computers, laptops, tablets or smartphones are equipped with high quality audio inputs and outputs that can generate and record signals in the audible frequency range (20 Hz – 20 kHz). Despite cutting off the direct currents completely, this range might be sufficient for working with a variety of sensors. In this presentation we look at the possibilities of making sure that such repurposing by design prevents any potential harm to the learner and to her or his personal equipment. These features seem essential for unsupervised alone experimenting and avoiding damage to expensive devices