South America
Data Analyst
We're looking for a self-motivated Data Analyst who is curious about our product and our users, and who is excited to seek out valuable insights. Most of our team are located in Buenos Aires. Athyna is a Global Employment Platform, making HR and Remote Work Tech products. We believe in the future of work. That's why we embrace technology and are a 100% global distributed team.
Why precision spraying is keying agriculture's Moneyball moment
Greg Kruger pauses for what seems like an eternity during his presentation, but it actually just lasts six seconds. The senior agronomist for BASF's xarvio digital farming division did it to prove a point about BASF's Smart Farming joint collaboration with Bosch that includes precision spraying technology the firms call Smart Spraying. The strategy teams machine-learning algorithms with computer vision to enable "green-on-green" spraying that distinguishes between weeds and crops in-season. Kruger's presentation was part of a BASF media briefing held before this week's Commodity Classic in New Orleans. "In the six seconds that I paused, we've taken 1,000 images [with Smart Spraying] on the boom," says Kruger.
Cross-Layer Approximation For Printed Machine Learning Circuits
Armeniakos, Giorgos, Zervakis, Georgios, Soudris, Dimitrios, Tahoori, Mehdi B., Henkel, Jörg
Printed electronics (PE) feature low non-recurring engineering costs and low per unit-area fabrication costs, enabling thus extremely low-cost and on-demand hardware. Such low-cost fabrication allows for high customization that would be infeasible in silicon, and bespoke architectures prevail to improve the efficiency of emerging PE machine learning (ML) applications. However, even with bespoke architectures, the large feature sizes in PE constraint the complexity of the ML models that can be implemented. In this work, we bring together, for the first time, approximate computing and PE design targeting to enable complex ML models, such as Multi-Layer Perceptrons (MLPs) and Support Vector Machines (SVMs), in PE. To this end, we propose and implement a cross-layer approximation, tailored for bespoke ML architectures. At the algorithmic level we apply a hardware-driven coefficient approximation of the ML model and at the circuit level we apply a netlist pruning through a full search exploration. In our extensive experimental evaluation we consider 14 MLPs and SVMs and evaluate more than 4300 approximate and exact designs. Our results demonstrate that our cross approximation delivers Pareto optimal designs that, compared to the state-of-the-art exact designs, feature 47% and 44% average area and power reduction, respectively, and less than 1% accuracy loss.
Learning cardiac activation maps from 12-lead ECG with multi-fidelity Bayesian optimization on manifolds
Pezzuto, Simone, Perdikaris, Paris, Costabal, Francisco Sahli
We propose a method for identifying an ectopic activation in the heart non-invasively. Ectopic activity in the heart can trigger deadly arrhythmias. The localization of the ectopic foci or earliest activation sites (EASs) is therefore a critical information for cardiologists in deciding the optimal treatment. In this work, we formulate the identification problem as a global optimization problem, by minimizing the mismatch between the ECG predicted by a cardiac model, when paced at a given EAS, and the observed ECG during the ectopic activity. Our cardiac model amounts at solving an anisotropic eikonal equation for cardiac activation and the forward bidomain model in the torso with the lead field approach for computing the ECG. We build a Gaussian process surrogate model of the loss function on the heart surface to perform Bayesian optimization. In this procedure, we iteratively evaluate the loss function following the lower confidence bound criterion, which combines exploring the surface with exploitation of the minimum region. We also extend this framework to incorporate multiple levels of fidelity of the model. We show that our procedure converges to the minimum only after $11.7\pm10.4$ iterations (20 independent runs) for the single-fidelity case and $3.5\pm1.7$ iterations for the multi-fidelity case. We envision that this tool could be applied in real time in a clinical setting to identify potentially dangerous EASs.
Blind Extraction of Equitable Partitions from Graph Signals
Scholkemper, Michael, Schaub, Michael
Finding equitable partitions is closely related to the extraction of graph symmetries and of interest in a variety of applications context such as node role detection, cluster synchronization, consensus dynamics, and network control problems. In this work we study a blind identification problem in which we aim to recover an equitable partition of a network without the knowledge of the network's edges but based solely on the observations of the outputs of an unknown graph filter. Specifically, we consider two settings. First, we consider a scenario in which we can control the input to the graph filter and present a method to extract the partition inspired by the well known Weisfeiler-Lehman (color refinement) algorithm. Second, we generalize this idea to a setting where only observe the outputs to random, low-rank excitations of the graph filter, and present a simple spectral algorithm to extract the relevant equitable partitions. Finally, we establish theoretical bounds on the error that this spectral detection scheme incurs and perform numerical experiments that illustrate our theoretical results and compare both algorithms.
These tiny spiders perform a synchronized pop-and-lock 'dance' as they hunt
Take a walk in French Guiana's tropical rainforests, and you'll encounter giant spiderwebs longer than a school bus. Inside, thousands of tiny, quarter-inch-long spiders wait for their prey to be trapped, allowing the predators to rush to overwhelm their victims. "In groups, they can capture prey up to 700 times [heavier] than each individual spider," such as moths and grasshoppers, says Raphaël Jeanson, an ethologist who studies the behavior of animals in their natural environment at the Center for Integrative Biology in Toulouse, France. Anelosimus eximius is a so-called "social" spider that lives in large, cooperative colonies--an extremely rare lifestyle for spiders. Each amber-colored South American spider is smaller than a ladybug, and even when they're hunting together, they pose no threat to people.
On the intrinsic dimensionality of Covid-19 data: a global perspective
Varghese, Abhishek, Santos-Fernandez, Edgar, Denti, Francesco, Mira, Antonietta, Mengersen, Kerrie
This paper aims to develop a global perspective of the complexity of the relationship between the standardised per-capita growth rate of Covid-19 cases, deaths, and the OxCGRT Covid-19 Stringency Index, a measure describing a country's stringency of lockdown policies. To achieve our goal, we use a heterogeneous intrinsic dimension estimator implemented as a Bayesian mixture model, called Hidalgo. We identify that the Covid-19 dataset may project onto two low-dimensional manifolds without significant information loss. The low dimensionality suggests strong dependency among the standardised growth rates of cases and deaths per capita and the OxCGRT Covid-19 Stringency Index for a country over 2020-2021. Given the low dimensional structure, it may be feasible to model observable Covid-19 dynamics with few parameters. Importantly, we identify spatial autocorrelation in the intrinsic dimension distribution worldwide. Moreover, we highlight that high-income countries are more likely to lie on low-dimensional manifolds, likely arising from aging populations, comorbidities, and increased per capita mortality burden from Covid-19. Finally, we temporally stratify the dataset to examine the intrinsic dimension at a more granular level throughout the Covid-19 pandemic.
Teleconnection patterns of different El Ni\~no types revealed by climate network curvature
Strnad, Felix M., Schlör, Jakob, Fröhlich, Christian, Goswami, Bedartha
The diversity of El Ni\~no events is commonly described by two distinct flavors, the Eastern Pacific (EP) and Central Pacific (CP) types. While the remote impacts, i.e. teleconnections, of EP and CP events have been studied for different regions individually, a global picture of their teleconnection patterns is still lacking. Here, we use Forman-Ricci curvature applied on climate networks constructed from 2-meter air temperature data to distinguish regional links from teleconnections. Our results confirm that teleconnection patterns are strongly influenced by the El Ni\~no type. EP events have primarily tropical teleconnections whereas CP events involve tropical-extratropical connections, particularly in the Pacific. Moreover, the central Pacific region does not have many teleconnections, even during CP events. It is mainly the eastern Pacific that mediates the remote influences for both El Ni\~no types.
Compartmental Models for COVID-19 and Control via Policy Interventions
Mehta, Swapneel, Kasmanoff, Noah
We demonstrate an approach to replicate and forecast the spread of the SARS-CoV-2 (COVID-19) pandemic using the toolkit of probabilistic programming languages (PPLs). Our goal is to study the impact of various modeling assumptions and motivate policy interventions enacted to limit the spread of infectious diseases. Using existing compartmental models we show how to use inference in PPLs to obtain posterior estimates for disease parameters. We improve popular existing models to reflect practical considerations such as the under-reporting of the true number of COVID-19 cases and motivate the need to model policy interventions for real-world data. We design an SEI3RD model as a reusable template and demonstrate its flexibility in comparison to other models. We also provide a greedy algorithm that selects the optimal series of policy interventions that are likely to control the infected population subject to provided constraints. We work within a simple, modular, and reproducible framework to enable immediate cross-domain access to the state-of-the-art in probabilistic inference with emphasis on policy interventions. We are not epidemiologists; the sole aim of this study is to serve as an exposition of methods, not to directly infer the real-world impact of policy-making for COVID-19.