Colombia
Nine coal miners die in gas explosion in Colombia
Nine people have died in an explosion at a coal mine in Colombia in the latest fatal accident to hit the country's mining sector. Emergency workers said they had rescued six miners from the shafts in Sutatausa, north of the capital, Bogotá. Colombia's national mining agency said a build-up of gases was thought to have caused the explosion at 16:00 (21:00 GMT) on Monday. It also published a list of recommendations it said it had made to the mine's operators after an inspection less than a month ago, in which it had warned of a potentially dangerous gas build-up. Many mines in Colombia are operated informally and without proper safety standards.
- North America (1.00)
- South America > Colombia > Bogotá D.C. > Bogotá (0.25)
- Leisure & Entertainment (1.00)
- Materials > Metals & Mining > Coal (0.53)
Revealing Geography-Driven Signals in Zone-Level Claim Frequency Models: An Empirical Study using Environmental and Visual Predictors
Alfonso-Sánchez, Sherly, Bravo, Cristián, Stankova, Kristina G.
Geographic context is often consider relevant to motor insurance risk, yet public actuarial datasets provide limited location identifiers, constraining how this information can be incorporated and evaluated in claim-frequency models. This study examines how geographic information from alternative data sources can be incorporated into actuarial models for Motor Third Party Liability (MTPL) claim prediction under such constraints. Using the BeMTPL97 dataset, we adopt a zone-level modeling framework and evaluate predictive performance on unseen postcodes. Geographic information is introduced through two channels: environmental indicators from OpenStreetMap and CORINE Land Cover, and orthoimagery released by the Belgian National Geographic Institute for academic use. We evaluate the predictive contribution of coordinates, environmental features, and image embeddings across three baseline models: generalized linear models (GLMs), regularized GLMs, and gradient-boosted trees, while raw imagery is modeled using convolutional neural networks. Our results show that augmenting actuarial variables with constructed geographic information improves accuracy. Across experiments, both linear and tree-based models benefit most from combining coordinates with environmental features extracted at 5 km scale, while smaller neighborhoods also improve baseline specifications. Generally, image embeddings do not improve performance when environmental features are available; however, when such features are absent, pretrained vision-transformer embeddings enhance accuracy and stability for regularized GLMs. Our results show that the predictive value of geographic information in zone-level MTPL frequency models depends less on model complexity than on how geography is represented, and illustrate that geographic context can be incorporated despite limited individual-level spatial information.
- South America > Colombia (0.04)
- Europe > Belgium > Flanders > Antwerp Province > Antwerp (0.04)
- Asia > Bangladesh (0.04)
- (8 more...)
- Health & Medicine (1.00)
- Banking & Finance > Insurance (1.00)
- Transportation > Ground > Road (0.93)
- (2 more...)
- Information Technology > Artificial Intelligence > Representation & Reasoning > Spatial Reasoning (1.00)
- Information Technology > Artificial Intelligence > Machine Learning > Statistical Learning (1.00)
- Information Technology > Artificial Intelligence > Machine Learning > Neural Networks > Deep Learning (0.88)
- Information Technology > Artificial Intelligence > Machine Learning > Ensemble Learning (0.87)
1 in 50 million split-colored lobster found in Massachusetts
The three-pound crustacean will live at an aquarium, offering a fun genetics lesson. More information Adding us as a Preferred Source in Google by using this link indicates that you would like to see more of our content in Google News results. The exciting discovery offers a lesson in genetics. Breakthroughs, discoveries, and DIY tips sent six days a week. A two-toned lobster is set to make a splash at the Woods Hole Science Aquarium in southeastern Massachusetts.
- North America > United States > Massachusetts (0.62)
- South America > Colombia (0.05)
- North America > United States > Maryland (0.05)
- North America > United States > Connecticut (0.05)
- North America > Central America (0.62)
- South America > Colombia (0.05)
- North America > United States > California (0.05)
- (10 more...)
- Media > News (1.00)
- Government > Regional Government > North America Government > United States Government (1.00)
- Government > Military (1.00)
Sparse Network Inference under Imperfect Detection and its Application to Ecological Networks
Zhang, Aoran, Wei, Tianyao, Guerrero, Maria J., Uribe, César A.
Abstract--Recovering latent structure from count data has received considerable attention in network inference, particularly when one seeks both cross-group interactions and within-group similarity patterns in bipartite networks, which is widely used in ecology research. Such networks are often sparse and inherently imperfect in their detection. Existing models mainly focus on interaction recovery, while the induced similarity graphs are much less studied. Moreover, sparsity is often not controlled, and scale is unbalanced, leading to oversparse or poorly rescaled estimates with degrading structural recovery. We impose nonconvex ℓ1/2 regularization on the latent similarity and connectivity structures to promote sparsity within-group similarity and cross-group connectivity with better relative scale. To solve it, we develop an ADMM-based algorithm with adaptive penalization and scale-aware initialization and establish its asymptotic feasibility and KKT stationarity of cluster points under mild regularity conditions. Experiments on synthetic and real-world ecological datasets demonstrate improved recovery of latent factors and similarity/connectivity structure relative to existing baselines. Index Terms--augmented Lagrangian, nonconvex nonsmooth optimization, nonnegative matrix factorization, link prediction, ecological network inference, structured sparse recovery I. INTRODUCTION This setting is inherent in sensing and monitoring applications [3], [4], where observations, such as counts, are obtained via an imperfect sampling process. In this paper, we are interested in ecological interaction networks describing how species associate with locations and how environments shape biodiversity patterns [5], [6].
- North America > United States (0.14)
- South America > Colombia > Santander Department (0.04)
- Europe > United Kingdom > England > Cambridgeshire > Cambridge (0.04)
Covariance-Based Structural Equation Modeling in Small-Sample Settings with $p>n$
Hasegawa, Hiroki, Tamura, Aoba, Okada, Yukihiko
Factor-based Structural Equation Modeling (SEM) relies on likelihood-based estimation assuming a nonsingular sample covariance matrix, which breaks down in small-sample settings with $p>n$. To address this, we propose a novel estimation principle that reformulates the covariance structure into self-covariance and cross-covariance components. The resulting framework defines a likelihood-based feasible set combined with a relative error constraint, enabling stable estimation in small-sample settings where $p>n$ for sign and direction. Experiments on synthetic and real-world data show improved stability, particularly in recovering the sign and direction of structural parameters. These results extend covariance-based SEM to small-sample settings and provide practically useful directional information for decision-making.
- Asia > Japan > Honshū > Kantō > Ibaraki Prefecture > Tsukuba (0.05)
- South America > Colombia (0.04)
New spider named for Pink Floyd devours bugs 6x its size
Maybe the tiny hunter should've been named after Metallica? More information Adding us as a Preferred Source in Google by using this link indicates that you would like to see more of our content in Google News results. Breakthroughs, discoveries, and DIY tips sent six days a week. We can call this newly discovered spider another brick--or web--in the wall. Scientists in Colombia named the new species in honor of English rock band Pink Floyd and the arachnid's preferred habitat--walls.
- South America > Colombia (0.27)
- Pacific Ocean (0.05)
- North America > United States > California (0.05)
- (2 more...)
- Media (0.51)
- Leisure & Entertainment (0.50)
Topological Detection of Hopf Bifurcations via Persistent Homology: A Functional Criterion from Time Series
Barrios, Jhonathan, Echávez, Yásser, Álvarez, Carlos F.
We propose a topological framework for the detection of Hopf bifurcations directly from time series, based on persistent homology applied to phase space reconstructions via Takens embedding within the framework of Topological Data Analysis. The central idea is that changes in the dynamical regime are reflected in the emergence or disappearance of a dominant one-dimensional homological features in the reconstructed attractor. To quantify this behavior, we introduce a simple and interpretable scalar topological functional defined as the maximum persistence of homology classes in dimension one. This functional is used to construct a computable criterion for identifying critical parameters in families of dynamical systems without requiring knowledge of the underlying equations. The proposed approach is validated on representative systems of increasing complexity, showing consistent detection of the bifurcation point. The results support the interpretation of dynamical transitions as topological phase transitions and demonstrate the potential of topological data analysis as a model-free tool for the quantitative analysis of nonlinear time series.
- North America > United States > New York (0.04)
- Europe > United Kingdom > England > Cambridgeshire > Cambridge (0.04)
- South America > Colombia (0.04)
- (4 more...)
Learning to Recorrupt: Noise Distribution Agnostic Self-Supervised Image Denoising
Monroy, Brayan, Bacca, Jorge, Tachella, Julián
Self-supervised image denoising methods have traditionally relied on either architectural constraints or specialized loss functions that require prior knowledge of the noise distribution to avoid the trivial identity mapping. Among these, approaches such as Noisier2Noise or Recorrupted2Recorrupted, create training pairs by adding synthetic noise to the noisy images. While effective, these recorruption-based approaches require precise knowledge of the noise distribution, which is often not available. We present Learning to Recorrupt (L2R), a noise distribution-agnostic denoising technique that eliminates the need for knowledge of the noise distribution. Our method introduces a learnable monotonic neural network that learns the recorruption process through a min-max saddle-point objective. The proposed method achieves state-of-the-art performance across unconventional and heavy-tailed noise distributions, such as log-gamma, Laplace, and spatially correlated noise, as well as signal-dependent noise models such as Poisson-Gaussian noise.
- Europe > France > Auvergne-Rhône-Alpes > Isère > Grenoble (0.04)
- South America > Colombia > Santander Department (0.04)
- North America > United States > California (0.04)
REALITrees: Rashomon Ensemble Active Learning for Interpretable Trees
Nguyen, Simon D., McTavish, Hayden, Hoffman, Kentaro, Rudin, Cynthia, McCormick, Tyler H.
Active learning reduces labeling costs by selecting samples that maximize information gain. A dominant framework, Query-by-Committee (QBC), typically relies on perturbation-based diversity by inducing model disagreement through random feature subsetting or data blinding. While this approximates one notion of epistemic uncertainty, it sacrifices direct characterization of the plausible hypothesis space. We propose the complementary approach: Rashomon Ensembled Active Learning (REAL) which constructs a committee by exhaustively enumerating the Rashomon Set of all near-optimal models. To address functional redundancy within this set, we adopt a PAC-Bayesian framework using a Gibbs posterior to weight committee members by their empirical risk. Leveraging recent algorithmic advances, we exactly enumerate this set for the class of sparse decision trees. Across synthetic and established active learning baselines, REAL outperforms randomized ensembles, particularly in moderately noisy environments where it strategically leverages expanded model multiplicity to achieve faster convergence.
- North America > United States > California > San Francisco County > San Francisco (0.14)
- North America > United States > New York > New York County > New York City (0.04)
- North America > United States > California > San Diego County > San Diego (0.04)
- (3 more...)
- Information Technology > Artificial Intelligence > Representation & Reasoning > Uncertainty > Bayesian Inference (0.48)
- Information Technology > Artificial Intelligence > Machine Learning > Learning Graphical Models > Directed Networks > Bayesian Learning (0.48)
- Information Technology > Artificial Intelligence > Machine Learning > Decision Tree Learning (0.35)