South America
ReQuestNet: A Foundational Learning model for Channel Estimation
Pratik, Kumar, Sadeghi, Pouriya, Cesa, Gabriele, Barghi, Sanaz, Soriaga, Joseph B., Yu, Yuanning, Bhattacharjee, Supratik, Behboodi, Arash
--In this paper, we present a novel neural architecture for channel estimation (CE) in 5G and beyond, the Recurrent Equivariant UERS Estimation Network (ReQuestNet). It incorporates several practical considerations in wireless communication systems, such as ability to handle variable number of resource block (RB), dynamic number of transmit layers, physical resource block groups (PRGs) bundling size (BS), demodulation reference signal (DMRS) patterns with a single unified model, thereby, drastically simplifying the CE pipeline. Besides it addresses several limitations of the legacy linear MMSE solutions, for example, by being independent of other reference signals and particularly by jointly processing MIMO layers and differently precoded channels with unknown precoding at the receiver . ReQuestNet comprises of two sub-units, CoarseNet followed by RefinementNet. CoarseNet performs per PRG, per transmit-receive (Tx-Rx) stream channel estimation, while Refinement-Net refines the CoarseNet channel estimate by incorporating correlations across differently precoded PRGs, and correlation across multiple input multiple output (MIMO) channel spatial dimensions (cross-MIMO). Simulation results demonstrate that ReQuestNet significantly outperforms genie minimum mean squared error (MMSE) CE across a wide range of channel conditions, delay-Doppler profiles, achieving up to 10dB gain at high SNRs. Notably, ReQuestNet generalizes effectively to unseen channel profiles, efficiently exploiting inter-PRG and cross-MIMO correlations under dynamic PRG BS and varying transmit layer allocations. The advent of 5G NR and the anticipated evolution toward sixth-generation (6G) networks have ushered in an era of unprecedented connectivity, data throughput, and system complexity. These developments necessitate advanced techniques for low-power, compute-efficient, and reliable wireless communication. Orthogonal Frequency Division Multiplexing (OFDM), a foundational modulation scheme in 5G NR, creates parallel communication channels across a large time-frequency grid. To acquire channel state information (CSI), the pilot signals known as demodulation reference signal (DMRS) is used, whose time-frequency positions and values are known a priori to both transmitter and receiver. Work completed while affiliated with Qualcomm Technologies Inc., USA.
SPIRA: Building an Intelligent System for Respiratory Insufficiency Detection
Ferreira, Renato Cordeiro, Gomes, Dayanne, Tamae, Vitor, Wernke, Francisco, Goldman, Alfredo
Respiratory insufficiency is a medic symptom in which a person gets a reduced amount of oxygen in the blood. This paper reports the experience of building SPIRA: an intelligent system for detecting respiratory insufficiency from voice. It compiles challenges faced in two succeeding implementations of the same architecture, summarizing lessons learned on data collection, training, and inference for future projects in similar systems.
A Metrics-Oriented Architectural Model to Characterize Complexity on Machine Learning-Enabled Systems
--How can the complexity of ML-enabled systems be managed effectively? The goal of this research is to investigate how complexity affects ML-Enabled Systems (MLES). T o address this question, this research aims to introduce a metrics-based architectural model to characterize the complexity of MLES. The goal is to support architectural decisions, providing a guideline for the inception and growth of these systems. This paper showcases the first step for creating the metrics-based architectural model: an extension of a reference architecture that can describe MLES to collect their metrics.
Variable-rate hierarchical CPC leads to acoustic unit discovery in speech
The success of deep learning comes from its ability to capture the hierarchical structure of data by learning high-level representations defined in terms of low-level ones. In this paper we explore self-supervised learning of hierarchical representations of speech by applying multiple levels of Contrastive Predictive Coding (CPC). We observe that simply stacking two CPC models does not yield significant improvements over single-level architectures. Inspired by the fact that speech is often described as a sequence of discrete units unevenly distributed in time, we propose a model in which the output of a low-level CPC module is non-uniformly downsampled to directly minimize the loss of a high-level CPC module. The latter is designed to also enforce a prior of separability and discreteness in its representations by enforcing dissimilarity of successive high-level representations through focused negative sampling, and by quantization of the prediction targets.
Charges dropped against teen pilot detained in Antarctica
Charges against an American influencer and teen pilot who has been stranded on a remote island in the Antarctic since June have been dropped. Ethan Guo, 19, is alleged to have illegally landed his plane in Chilean territory after embarking on a solo trip to all seven continents to raise money for cancer research, according to local authorities. They accused him of providing false flight plan information to officials who detained him and opened an investigation. A judge has ordered him to leave the area, pay a $30,000 (ยฃ22,332) donation to a children's cancer foundation and is banned from re-entering Chilean territory for three years. Mr Guo made headlines last year when he began an attempt to become the youngest person to fly solo to all seven continents and collect donations for research into childhood cancer.
Using Imperfect Synthetic Data in Downstream Inference Tasks
Byun, Yewon, Gupta, Shantanu, Lipton, Zachary C., Childers, Rachel Leah, Wilder, Bryan
Predictions and generations from large language models are increasingly being explored as an aid to computational social science and human subject research in limited data regimes. While previous technical work has explored the potential to use model-predicted labels for unlabeled data in a principled manner, there is increasing interest in using large language models to generate entirely new synthetic samples (also termed as synthetic simulations), such as in responses to surveys. However, it is not immediately clear by what means practitioners can combine such data with real data and yet produce statistically valid conclusions upon them. In this work, we introduce a new estimator based on generalized method of moments, providing a hyperparameter-free solution with strong theoretical guarantees to address the challenge at hand. Surprisingly, we find that interactions between the moment residuals of synthetic data and those of real data can improve estimates of the target parameter. We empirically validate the finite-sample performance of our estimator across different regression tasks in computational social science applications, demonstrating large empirical gains.
Safeguarding Generative AI Applications in Preclinical Imaging through Hybrid Anomaly Detection
Binda, Jakub, Paneta, Valentina, Eleftheriadis, Vasileios, Chung, Hongkyou, Papadimitroulas, Panagiotis, Chung, Neo Christopher
Generative AI holds great potentials to automate and enhance data synthesis in nuclear medicine. However, the high-stakes nature of biomedical imaging necessitates robust mechanisms to detect and manage unexpected or erroneous model behavior. We introduce development and implementation of a hybrid anomaly detection framework to safeguard GenAI models in BIOEMTECH's eyes(TM) systems. Two applications are demonstrated: Pose2Xray, which generates synthetic X-rays from photographic mouse images, and DosimetrEYE, which estimates 3D radiation dose maps from 2D SPECT/CT scans. In both cases, our outlier detection (OD) enhances reliability, reduces manual oversight, and supports real-time quality control. This approach strengthens the industrial viability of GenAI in preclinical settings by increasing robustness, scalability, and regulatory compliance.
Semi-automated Fact-checking in Portuguese: Corpora Enrichment using Retrieval with Claim extraction
Gomes, Juliana Resplande Sant'anna, Filho, Arlindo Rodrigues Galvรฃo
The accelerated dissemination of disinformation often outpaces the capacity for manual fact-checking, highlighting the urgent need for Semi-Automated Fact-Checking (SAFC) systems. Within the Portuguese language context, there is a noted scarcity of publicly available datasets ( corpora) that integrate external evidence, an essential component for developing robust AFC systems, as many existing resources focus solely on classification based on intrinsic text features. This dissertation addresses this gap by developing, applying, and analyzing a methodology to enrich Portuguese news corpora (Fake.Br, COVID19.BR, MuMiN-PT) with external evidence. The approach simulates a user's verification process, employing Large Language Models (LLMs, specifically Gemini 1.5 Flash) to extract the main claim from texts and search engine APIs (Google Search API, Google FactCheck Claims Search API) to retrieve relevant external documents (evidence). Additionally, a data validation and pre-processing framework, including near-duplicate detection, is introduced to enhance the quality of the base corpora. The main results demonstrate the methodology's viability, providing enriched corpora and analyses that confirm the utility of claim extraction, the influence of original data characteristics on the process, and the positive impact of enrichment on the performance of classification models (Bertimbau and Gemini 1.5 Flash), especially with fine-tuning. This work contributes valuable resources and insights for advancing SAFC in Portuguese.
In 'Alien: Earth', the Future Is a Corporate Hellscape
Seventeen years ago, Noah Hawley became a father during the Great Recession. If you look at everything he's written since having children--including the TV series Fargo and Legion--Hawley says it all revolves around the same question every parent faces: "How are we supposed to raise these people in the world that we're living in?" Hawley's new series, Alien: Earth, which premieres August 12 on Hulu and FX, explores this question even more directly than his previous work. Set two years before the original Alien in 2120, it imagines a future where the race for immortality has led to three competing technologies: synths (AI minds in synthetic bodies), cyborgs (humans with cybernetic enhancements), and hybrids (human minds downloaded into synthetic bodies). When a deep space research vessel, the USCSS Maginot, crashes into Earth carrying five captured alien species, a megacorporation called Prodigy sends six hybrids to investigate. The first-ever hybrid, Wendy, played by Sydney Chandler, was a terminally ill child before she was selected for the immortality experiment, just like the rest of Prodigy's hybrids, all six of whom wake up in super-strong, super-fast, synthetic adult bodies that will never age.
Open-Source Agentic Hybrid RAG Framework for Scientific Literature Review
Nagori, Aditya, Casonatto, Ricardo Accorsi, Gautam, Ayush, Cheruvu, Abhinav Manikantha Sai, Kamaleswaran, Rishikesan
The surge in scientific publications challenges traditional review methods, demanding tools that integrate structured metadata with full-text analysis. Hybrid Retrieval Augmented Generation (RAG) systems, combining graph queries with vector search offer promise but are typically static, rely on proprietary tools, and lack uncertainty estimates. We present an agentic approach that encapsulates the hybrid RAG pipeline within an autonomous agent capable of (1) dynamically selecting between GraphRAG and VectorRAG for each query, (2) adapting instruction-tuned generation in real time to researcher needs, and (3) quantifying uncertainty during inference. This dynamic orchestration improves relevance, reduces hallucinations, and promotes reproducibility. Our pipeline ingests bibliometric open-access data from PubMed, arXiv, and Google Scholar APIs, builds a Neo4j citation-based knowledge graph (KG), and embeds full-text PDFs into a FAISS vector store (VS) using the all-MiniLM-L6-v2 model. A Llama-3.3-70B agent selects GraphRAG (translating queries to Cypher for KG) or VectorRAG (combining sparse and dense retrieval with re-ranking). Instruction tuning refines domain-specific generation, and bootstrapped evaluation yields standard deviation for evaluation metrics. On synthetic benchmarks mimicking real-world queries, the Instruction-Tuned Agent with Direct Preference Optimization (DPO) outperforms the baseline, achieving a gain of 0.63 in VS Context Recall and a 0.56 gain in overall Context Precision. Additional gains include 0.24 in VS Faithfulness, 0.12 in both VS Precision and KG Answer Relevance, 0.11 in overall Faithfulness score, 0.05 in KG Context Recall, and 0.04 in both VS Answer Relevance and overall Precision. These results highlight the system's improved reasoning over heterogeneous sources and establish a scalable framework for autonomous, agentic scientific discovery.