Africa
Saudi crown prince to visit U.S. with defense, AI and nuclear energy on agenda
Saudi crown prince to visit U.S. with defense, AI and nuclear energy on agenda In his upcoming visit to the White House, the crown prince is seeking security guarantees and wants access to artificial intelligence technology and progress toward a deal on a civilian nuclear program. RIYADH/WASHINGTON - A visit by Saudi Arabia's de facto ruler to the White House for talks on Tuesday with U.S. President Donald Trump aims to deepen decades-old cooperation on oil and security while broadening ties in commerce, technology and potentially even nuclear energy. It will be the first trip by Crown Prince Mohammed bin Salman to the U.S. since the 2018 killing of Saudi critic Jamal Khashoggi by Saudi agents in Istanbul, which caused a global uproar. U.S. intelligence concluded that the crown prince approved the capture or killing of Khashoggi, a prominent critic. The crown prince, widely known by his initials MBS, denied ordering the operation but acknowledged responsibility as the kingdom's de facto ruler.
US will give visa appointment priority to World Cup ticket holders
President Donald Trump has announced US embassies will give visa appointment priority to travellers with tickets to the 2026 World Cup. The Fifa Prioritised Appointment Scheduling System (Pass) will allow World Cup ticket-holders with long wait times to opt with Fifa for a prioritised interview, Trump said at the White House on Monday. Ticket-holders for the tournament - set for next June and July in the US, Canada and Mexico - will not be automatically granted a tourist visa, said Secretary of State Marco Rubio. But foreign nationals with tickets to World Cup football matches could get an interview at an embassy or consulate within six to eight weeks of applying, Rubio said. Your ticket is not a visa; it doesn't guarantee admission to the US, Rubio said, also at the White House on Monday.
PCA++: How Uniformity Induces Robustness to Background Noise in Contrastive Learning
Wu, Mingqi, Sun, Qiang, Yang, Yi
High-dimensional data often contain low-dimensional signals obscured by structured background noise, which limits the effectiveness of standard PCA. Motivated by contrastive learning, we address the problem of recovering shared signal subspaces from positive pairs, paired observations sharing the same signal but differing in background. Our baseline, PCA+, uses alignment-only contrastive learning and succeeds when background variation is mild, but fails under strong noise or high-dimensional regimes. To address this, we introduce PCA++, a hard uniformity-constrained contrastive PCA that enforces identity covariance on projected features. PCA++ has a closed-form solution via a generalized eigenproblem, remains stable in high dimensions, and provably regularizes against background interference. We provide exact high-dimensional asymptotics in both fixed-aspect-ratio and growing-spike regimes, showing uniformity's role in robust signal recovery. Empirically, PCA++ outperforms standard PCA and alignment-only PCA+ on simulations, corrupted-MNIST, and single-cell transcriptomics, reliably recovering condition-invariant structure. More broadly, we clarify uniformity's role in contrastive learning, showing that explicit feature dispersion defends against structured noise and enhances robustness.
A Review of Statistical and Machine Learning Approaches for Coral Bleaching Assessment
Coral bleaching is a major concern for marine ecosystems; more than half of the world's coral reefs have either bleached or died over the past three decades. Increasing sea surface temperatures, along with various spatiotemporal environmental factors, are considered the primary reasons behind coral bleaching. The statistical and machine learning communities have focused on multiple aspects of the environment in detail. However, the literature on various stochastic modeling approaches for assessing coral bleaching is extremely scarce. Data-driven strategies are crucial for effective reef management, and this review article provides an overview of existing statistical and machine learning methods for assessing coral bleaching. Statistical frameworks, including simple regression models, generalized linear models, generalized additive models, Bayesian regression models, spatiotemporal models, and resilience indicators, such as Fisher's Information and Variance Index, are commonly used to explore how different environmental stressors influence coral bleaching. On the other hand, machine learning methods, including random forests, decision trees, support vector machines, and spatial operators, are more popular for detecting nonlinear relationships, analyzing high-dimensional data, and allowing integration of heterogeneous data from diverse sources. In addition to summarizing these models, we also discuss potential data-driven future research directions, with a focus on constructing statistical and machine learning models in specific contexts related to coral bleaching.
PCA recovery thresholds in low-rank matrix inference with sparse noise
Adomaityte, Urte, Sicuro, Gabriele, Vivo, Pierpaolo
We study the high-dimensional inference of a rank-one signal corrupted by sparse noise. The noise is modelled as the adjacency matrix of a weighted undirected graph with finite average connectivity in the large size limit. Using the replica method from statistical physics, we analytically compute the typical value of the top eigenvalue, the top eigenvector component density, and the overlap between the signal vector and the top eigenvector. The solution is given in terms of recursive distributional equations for auxiliary probability density functions which can be efficiently solved using a population dynamics algorithm. Specialising the noise matrix to Poissonian and Random Regular degree distributions, the critical signal strength is analytically identified at which a transition happens for the recovery of the signal via the top eigenvector, thus generalising the celebrated BBP transition to the sparse noise case. In the large-connectivity limit, known results for dense noise are recovered. Analytical results are in agreement with numerical diagonalisation of large matrices.
Coordinate Descent for Network Linearization
Rakhlin, Vlad, Jevnisek, Amir, Avidan, Shai
ReLU activations are the main bottleneck in Private Inference that is based on ResNet networks. This is because they incur significant inference latency. Reducing ReLU count is a discrete optimization problem, and there are two common ways to approach it. Most current state-of-the-art methods are based on a smooth approximation that jointly optimizes network accuracy and ReLU budget at once. However, the last hard thresholding step of the optimization usually introduces a large performance loss. We take an alternative approach that works directly in the discrete domain by leveraging Coordinate Descent as our optimization framework. In contrast to previous methods, this yields a sparse solution by design. We demonstrate, through extensive experiments, that our method is State of the Art on common benchmarks.
OlmoEarth: Stable Latent Image Modeling for Multimodal Earth Observation
Herzog, Henry, Bastani, Favyen, Zhang, Yawen, Tseng, Gabriel, Redmon, Joseph, Sablon, Hadrien, Park, Ryan, Morrison, Jacob, Buraczynski, Alexandra, Farley, Karen, Hansen, Joshua, Howe, Andrew, Johnson, Patrick Alan, Otterlee, Mark, Schmitt, Ted, Pitelka, Hunter, Daspit, Stephen, Ratner, Rachel, Wilhelm, Christopher, Wood, Sebastian, Jacobi, Mike, Kerner, Hannah, Shelhamer, Evan, Farhadi, Ali, Krishna, Ranjay, Beukema, Patrick
Earth observation data presents a unique challenge: it is spatial like images, sequential like video or text, and highly multimodal. We present OlmoEarth: a multimodal, spatio-temporal foundation model that employs a novel self-supervised learning formulation, masking strategy, and loss all designed for the Earth observation domain. OlmoEarth achieves state-of-the-art performance compared to 12 other foundation models across a variety of research benchmarks and real-world tasks from external partners. When evaluating embeddings OlmoEarth achieves the best performance on 15 out of 24 tasks, and with full fine-tuning it is the best on 19 of 29 tasks. We deploy OlmoEarth as the backbone of an end-to-end platform for data collection, labeling, training, and inference of Earth observation models. The OlmoEarth Platform puts frontier foundation models and powerful data management tools into the hands of non-profits and NGOs working to solve the world's biggest problems. OlmoEarth source code, training data, and pre-trained weights are available at $\href{https://github.com/allenai/olmoearth_pretrain}{\text{https://github.com/allenai/olmoearth_pretrain}}$.
TEMPO: Global Temporal Building Density and Height Estimation from Satellite Imagery
Glazer, Tammy, Hacheme, Gilles Q., Zaytar, Akram, Marotti, Luana, Michaels, Amy, Tadesse, Girmaw Abebe, White, Kevin, Dodhia, Rahul, Zolli, Andrew, Becker-Reshef, Inbal, Ferres, Juan M. Lavista, Robinson, Caleb
We present TEMPO, a global, temporally resolved dataset of building density and height derived from high-resolution satellite imagery using deep learning models. We pair building footprint and height data from existing datasets with quarterly PlanetScope basemap satellite images to train a multi-task deep learning model that predicts building density and building height at a 37.6-meter per pixel resolution. We apply this model to global PlanetScope basemaps from Q1 2018 through Q2 2025 to create global, temporal maps of building density and height. We validate these maps by comparing against existing building footprint datasets. Our estimates achieve an F1 score between 85% and 88% on different hand-labeled subsets, and are temporally stable, with a 0.96 five-year trend-consistency score. TEMPO captures quarterly changes in built settlements at a fraction of the computational cost of comparable approaches, unlocking large-scale monitoring of development patterns and climate impacts essential for global resilience and adaptation efforts.
FLEX: Feature Importance from Layered Counterfactual Explanations
Keshtmand, Nawid, Nzoyem, Roussel Desmond, Clark, Jeffrey Nicholas
Machine learning models achieve state-of-the-art performance across domains, yet their lack of interpretability limits safe deployment in high-stakes settings. Counterfactual explanations are widely used to provide actionable "what-if" recourse, but they typically remain instance-specific and do not quantify which features systematically drive outcome changes within coherent regions of the feature space or across an entire dataset. We introduce FLEX (Feature importance from Layered counterfactual EXplanations), a model- and domain-agnostic framework that converts sets of counterfactuals into feature change frequency scores at local, regional, and global levels. FLEX generalises local change-frequency measures by aggregating across instances and neighbourhoods, offering interpretable rankings that reflect how often each feature must change to flip predictions. The framework is compatible with different counterfactual generation methods, allowing users to emphasise characteristics such as sparsity, feasibility, or actionability, thereby tailoring the derived feature importances to practical constraints. We evaluate FLEX on two contrasting tabular tasks: traffic accident severity prediction and loan approval, and compare FLEX to SHAP- and LIME-derived feature importance values. Results show that (i) FLEX's global rankings correlate with SHAP while surfacing additional drivers, and (ii) regional analyses reveal context-specific factors that global summaries miss. FLEX thus bridges the gap between local recourse and global attribution, supporting transparent and intervention-oriented decision-making in risk-sensitive applications.
T2IBias: Uncovering Societal Bias Encoded in the Latent Space of Text-to-Image Generative Models
Sufian, Abu, Distante, Cosimo, Leo, Marco, Salam, Hanan
Text-to-image (T2I) generative models are largely used in AI-powered real-world applications and value creation. However, their strategic deployment raises critical concerns for responsible AI management, particularly regarding the reproduction and amplification of race- and gender-related stereotypes that can undermine organizational ethics. In this work, we investigate whether such societal biases are systematically encoded within the pretrained latent spaces of state-of-the-art T2I models. We conduct an empirical study across the five most popular open-source models, using ten neutral, profession-related prompts to generate 100 images per profession, resulting in a dataset of 5,000 images evaluated by diverse human assessors representing different races and genders. We demonstrate that all five models encode and amplify pronounced societal skew: caregiving and nursing roles are consistently feminized, while high-status professions such as corporate CEO, politician, doctor, and lawyer are overwhelmingly represented by males and mostly White individuals. We further identify model-specific patterns, such as QWEN-Image's near-exclusive focus on East Asian outputs, Kandinsky's dominance of White individuals, and SDXL's comparatively broader but still biased distributions. These results provide critical insights for AI project managers and practitioners, enabling them to select equitable AI models and customized prompts that generate images in alignment with the principles of responsible AI. We conclude by discussing the risks of these biases and proposing actionable strategies for bias mitigation in building responsible GenAI systems. The code and Data Repository: https://github.com/Sufianlab/T2IBias