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Signatures of planets and Galactic subpopulations in solar analogs. Precise chemical abundances with neural networks

Martos, Giulia, Meléndez, Jorge, Spina, Lorenzo, Lucatello, Sara

arXiv.org Artificial Intelligence

The aim of this work is to obtain precise atmospheric parameters and chemical abundances automatically for solar twins and analogs to find signatures of exoplanets, as well as to assess how peculiar the Sun is compared to these stars and to analyze any possible fine structures in the Galactic thin disk. We developed a neural network (NN) algorithm using Python to obtain these parameters for a sample of 99 solar twins and solar analogs previously studied in the literature from normalized high-quality spectra from HARPS, with a resolving power of R $\sim$ 115000 and a signal-to-noise ratio S/N > 400. We obtained precise atmospheric parameters and abundance ratios [X/Fe] of 20 chemical elements (Li, C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, and Ba). The results are in line with the literature, with average differences and standard deviations of $(2 \pm 27)$ K for T$_{\rm eff}$, $(0.00 \pm 0.06)$ dex for log g, $(0.00 \pm 0.02)$ dex for [Fe/H], $(-0.01 \pm 0.05)$ km s$^{-1}$ for microturbulence velocity, $(0.02 \pm 0.08)$ km s$^{-1}$ for the macro turbulence velocity, and $(-0.12 \pm 0.26)$ km s$^{-1}$ for the projected rotational velocity (vsin$i$). Regarding the chemical abundances, most of the elements agree with the literature within 0.01 - 0.02 dex. The abundances were corrected from the effects of the Galactic chemical evolution and analyzed with the condensation temperature (T$_{\rm cond}$) to verify whether the stars presented depletion of refractories compared to volatiles. We found that the Sun is more depleted in refractory elements compared to volatiles than 89% of the studied solar analogs, with a significance of 9.5$σ$ when compared to the stars without detected exoplanets. We also found the possible presence of three subpopulations in the solar analogs: one Cu-rich, one Cu-poor, and the last one slightly older and poor in Na.


When a Machine Becomes an Addict

Slate

Sounds like a tongue twister, doesn't it?" "What do you think you're doing?" shrieked Méndez's voice behind me. "What the fuck is going on with you?" I could tell that she was about to cry. I stopped the treadmill and got off carefully, without entirely disconnecting.


Actionable Recourse via GANs for Mobile Health

Chien, Jennifer, Guitart, Anna, del Rio, Ana Fernandez, Perianez, Africa, Bellhouse, Lauren

arXiv.org Artificial Intelligence

Mobile health apps provide a unique means of collecting data that can be used to deliver adaptive interventions.The predicted outcomes considerably influence the selection of such interventions. Recourse via counterfactuals provides tangible mechanisms to modify user predictions. By identifying plausible actions that increase the likelihood of a desired prediction, stakeholders are afforded agency over their predictions. Furthermore, recourse mechanisms enable counterfactual reasoning that can help provide insights into candidates for causal interventional features. We demonstrate the feasibility of GAN-generated recourse for mobile health applications on ensemble-survival-analysis-based prediction of medium-term engagement in the Safe Delivery App, a digital training tool for skilled birth attendants.


Intuit Accelerator Combines Fintech For Good With AI

#artificialintelligence

José V. Fernández first got interested in using technology to ramp up financial inclusion when he first arrived in New York City from Spain around 10 years ago. His job working as a trade officer for Spain didn't impress numerous prospective landlords, none of whom would rent him an apartment because he lacked a U.S. credit score. Finally, one company agreed to sign a one-year lease, but only if Fernández paid six months of his pricey Manhattan rent ahead of time. A few years after that, Fernández co-founded a fintech firm to open up microloans to unbanked people in West Africa. Then, last year, he founded Bankuish, which aims to give gig workers and freelancers a way to access banking services they normally wouldn't be able to tap.


A Time Series Approach To Player Churn and Conversion in Videogames

del Río, Ana Fernández, Guitart, Anna, Periáñez, África

arXiv.org Machine Learning

Players of a free-to-play game are divided into three main groups: non-paying active users, paying active users and inactive users. A State Space time series approach is then used to model the daily conversion rates between the different groups, i.e., the probability of transitioning from one group to another. This allows, not only for predictions on how these rates are to evolve, but also for a deeper understanding of the impact that in-game planning and calendar effects have. It is also used in this work for the detection of marketing and promotion campaigns about which no information is available. In particular, two different State Space formulations are considered and compared: an Autoregressive Integrated Moving Average process and an Unobserved Components approach, in both cases with a linear regression to explanatory variables. Both yield very close estimations for covariate parameters, producing forecasts with similar performances for most transition rates. While the Unobserved Components approach is more robust and needs less human intervention in regards to model definition, it produces significantly worse forecasts for non-paying user abandonment probability. More critically, it also fails to detect a plausible marketing and promotion campaign scenario.


AI beyond the buzz HIMSS Europe Conference

#artificialintelligence

Artificial Intelligence (AI) in healthcare is expected to revolutionise the sector. Expectations are high and since 2015 the number of medical algorithms approved by the FDA has grown exponentially. We can see it in this interesting infographic designed by Dr. Bertalan Mesko (@Berci), known as the Medical Futurist, which shows that in 2014 only AliveCor's algorithm for the detection of atrial fibrillation was approved, and then in recent years dozens of algorithms have burst onto the scene with the go-ahead of the FDA, among them, products from Apple and Verily. However, the hype in which AI has been involved has left us some disappointments. But in recent years, a great number of startups and healthcare organisations are getting tangible results in AI applied to different medical fields.


The 2^k Neighborhoods for Grid Path Planning

Rivera, Nicolás (University of Cambridge) | Hernández, Carlos (Universidad Andrés Bello) | Hormazábal, Nicolás (Universidad Andrés Bello) | Baier, Jorge A (Pontificia Universidad Católica de Chile)

Journal of Artificial Intelligence Research

Grid path planning is an important problem in AI. Its understanding has been key for the development of autonomous navigation systems. An interesting and rather surprising fact about the vast literature on this problem is that only a few neighborhoods have been used when evaluating these algorithms. Indeed, only the 4- and 8-neighborhoods are usually considered, and rarely the 16-neighborhood. This paper describes three contributions that enable the construction of effective grid path planners for extended 2k-neighborhoods; that is, neighborhoods that admit 2k neighbors per state, where k is a parameter. First, we provide a simple recursive definition of the 2k-neighborhood in terms of the 2k-1-neighborhood. Second, we derive distance functions, for any k ≥ 2, which allow us to propose admissible heuristics that are perfect for obstacle-free grids, which generalize the well-known Manhattan and Octile distances. Third, we define the notion of canonical path for the 2k-neighborhood; this allows us to incorporate our neighborhoods into two versions of A*, namely Canonical A* and Jump Point Search (JPS), whose performance, we show, scales well when increasing k. Our empirical evaluation shows that, when increasing k, the cost of the solution found improves substantially.  Used with the 2k-neighborhood, Canonical A* and JPS, in many configurations, are also superior to the any-angle path planner Theta* both in terms of solution quality and runtime. Our planner is competitive with one implementation of the any-angle path planner, ANYA in some configurations. Our main practical conclusion is that standard, well-understood grid path planning technology may provide an effective approach to any-angle grid path planning.


Miguel Pereira Hernández: A Day in the Life of a Dashmote Data Scientist

#artificialintelligence

He is also, not surprisingly, making a living out of numbers. This tall and young Spaniard, with a degree in mathematics from the Polytechnic University of Catalonia, has been a fixture of the Dashmote's data science team since January. So how did Miguel, a native of Barcelona, end up living in the land of cheese and polders, working for an AI scale-up? It was during his degree that he knew he wanted to go into computer science. It wasn't a career change that brought him to the Netherlands, but love.


On the Complexity of Extended and Proportional Justified Representation

Aziz, Haris (Data61, CSIRO and UNSW, Sydney) | Elkind, Edith (University of Oxford, Oxford) | Huang, Shenwei (University of New South Wales, Sydney) | Lackner, Martin (TU Wien, Vienna) | Sanchez-Fernandez, Luis (Universidad Carlos III de Madrid) | Skowron, Piotr (TU Berlin, Berlin)

AAAI Conferences

We consider the problem of selecting a fixed-size committee based on approval ballots. It is desirable to have a committee in which all voters are fairly represented. Aziz et al. (2015a; 2017) proposed an axiom called extended justified representation (EJR), which aims to capture this intuition; subsequently, Sanchez-Fernandez et al. (2017) proposed a weaker variant of this axiom called proportional justified representation (PJR). It was shown that it is coNP-complete to check whether a given committee provides EJR, and it was conjectured that it is hard to find a committee that provides EJR. In contrast, there are polynomial-time computable voting rules that output committees providing PJR, but the complexity of checking whether a given committee provides PJR was an open problem. In this paper, we answer open questions from prior work by showing that EJR and PJR have the same worst-case complexity: we provide two polynomial-time algorithms that output committees providing EJR, yet we show that it is coNP-complete to decide whether a given committee provides PJR. We complement the latter result by fixed-parameter tractability results.


TEO the ironing robot is here to steal the job you never wanted anyway

#artificialintelligence

This robot will ensure that your work trousers and shirts remain wrinkle-free. And it promises to do other chores, as well. If you're an enlightened, modern sort of person, you feel that ironing duties should be split 50/50 between men and women. They believe the task of ironing should reside entirely with one member of the household: The domestic robot. With that in mind, they've developed a humanoid robot called TEO that has mastered the art of ensuring your shirts and trousers are wrinkle-free -- courtesy of some smart image recognition algorithms.