Coarse-to-Fine Adaptive People Detection for Video Sequences by Maximizing Mutual Information

Applying people detectors to unseen data is challenging since patterns distributions, such as viewpoints, motion, poses, backgrounds, occlusions and people sizes, may significantly differ from the ones of the training dataset. In this paper, we propose a coarse-to-fine framework to adapt frame by frame people detectors during runtime classification, without requiring any additional manually labeled ground truth apart from the offline training of the detection model. Such adaptation make use of multiple detectors mutual information, i.e., similarities and dissimilarities of detectors estimated and agreed by pair-wise correlating their outputs. Globally, the proposed adaptation discriminates between relevant instants in a video sequence, i.e., identifies the representative frames for an adaptation of the system. Locally, the proposed adaptation identifies the best configuration (i.e., detection threshold) of each detector under analysis, maximizing the mutual information to obtain the detection threshold of each detector. The proposed coarse-to-fine approach does not require training the detectors for each new scenario and uses standard people detector outputs, i.e., bounding boxes. The experimental results demonstrate that the proposed approach outperforms state-of-the-art detectors whose optimal threshold configurations are previously determined and fixed from offline training dataThis work has been partially supported by the Spanish government under the project TEC2014-53176-R (HAVideo

Enhancing Multi-Camera People Detection by Online Automatic Parametrization Using Detection Transfer and Self-Correlation Maximization

Finding optimal parametrizations for people detectors is a complicated task due to the large number of parameters and the high variability of application scenarios. In this paper, we propose a framework to adapt and improve any detector automatically in multi-camera scenarios where people are observed from various viewpoints. By accurately transferring detector results between camera viewpoints and by self-correlating these transferred results, the best configuration (in this paper, the detection threshold) for each detector-viewpoint pair is identified online without requiring any additional manually-labeled ground truth apart from the offline training of the detection model. Such a configuration consists of establishing the confidence detection threshold present in every people detector, which is a critical parameter affecting detection performance. The experimental results demonstrate that the proposed framework improves the performance of four different state-of-the-art detectors (DPM , ACF, faster R-CNN, and YOLO9000) whose Optimal Fixed Thresholds (OFTs) have been determined and fixed during training time using standard datasets. Keywords: self-correlationmaximization;multi-camera; people detection; automaticThis work has been partially supported by the Spanish government under the project TEC2014-53176-

Hydration and Diffusion Mechanism of Uranyl in Montmorillonite Clay: Molecular Dynamics Using an Ab Initio Potential

Permanent geological repositories lined with bentonite, a montmorillonite-containing clay, is one of the options considered for the storage of high-level radioactive waste. If the fuel rods were dissolved by a water leak, the clay would exchange its cations with the radioactive cations, slowing down their diffusion to the environment. We present an ab initio force field for the uranyl–montmorillonite interaction based on the hydrated ion model, i.e., recognizing the [UO₂(H₂O)₅]²⁺ as the cationic species. This new interaction potential was used to run molecular dynamics simulations of the hydrated clay system. The uranyl aqua ion formed outer-sphere complexes with the clay layers, in agreement with EXAFS data. The hydrate is strongly bound, forming 1.4 hydrogen bonds between the first shell and clay oxygens. Uranyl–clay interaction sites were identified as groups of three Mg substitutions. Increasing the uranyl concentration enhances mobility due to partial surface coverage. Uranyl diffuses by means of a hopping mechanism. The constrictivity factor, δ_int, from the simulation self-diffusion coefficient of [UO₂]²⁺ was calculated. A semiquantitative agreement with the experimental datum was obtained

MitoBlue: A Nontoxic and Photostable Blue-Emitting Dye That Selectively Labels Functional Mitochondria

We report the discovery of a fluorogenic dye, <i>N</i>¹,<i>N</i>³-di­(2-aminidonaphthalen-6-yl) propane-1,3-diamine, MitoBlue, which selectively stains functional mitochondria while displaying low toxicity, bright blue emission, and high resistance to photobleaching. Additionally, we show that a biotin-labeled MitoBlue derivative can be used as a handle for the delivery of streptavidin-tagged species to the mitochondria

Outstanding Atomic Order in Ruddlesden–Popper Oxide Microcrystals

Ruddlesden–Popper’s manganates, A_<i>n</i>+1Mn_<i>n</i>O_3<i>n</i>+1, built from the ordered intergrowth between one rock-salt and <i>n</i> perovskite blocks, display a wide variety of functionalities related to their physical-chemistry properties which can be in principle tuned by chemical modifications. Nevertheless, the poor thermodynamic stability of the high members constitutes an inherent impediment, limiting the development of new functionalities in this family. Actually, for <i>n</i> ≥ 2, defects involving disordered intergrowths between perovskite and rock-salt blocks are always present avoiding the correct characterization of their properties. For that purpose, the use of sophisticated and expensive physical methods is required. In this article, the stabilization, following a chemical strategy, of micrometric La_0.5Ca_2.5Mn₂O₇ crystalline particles exhibiting a well ordered distribution of two perovskite and one rock-salt block, according to an ideal <i>n</i> = 2 unit cell, is reported. This apparently long-range structural ordering is linked to an unconventional short-range order–disorder phenomenon of La and Ca cations, characterized at the atomic level, which allows a rational explanation of the crystallochemical and magnetic properties of this Ruddlesden–Popper compound

Supramolecular Immobilization of Xanthine Oxidase on Electropolymerized Matrix of Functionalized Hybrid Gold Nanoparticles/Single-Walled Carbon Nanotubes for the Preparation of Electrochemical Biosensors

Glassy carbon electrodes modified with single-walled carbon nanotubes and a three-dimensional network of electropolymerized Au nanoparticles capped with 2-mercaptoethanesulfonic acid, <i>p</i>-aminothiophenol, and 1-adamantanethiol were used as hybrid electrochemical platforms for supramolecular immobilization of a synthesized artificial neoglycoenzyme of xanthine oxidase and β-cyclodextrin through host–guest interactions. The ensemble was further employed for the bioelectrochemical determination of xanthine. The biosensor showed fast amperometric response within 5 s and a linear behavior in the 50 nM to 9.5 μM xanthine concentration range with high sensitivity, 2.47 A/(M cm²), and very low detection limit of 40 nM. The stability of the biosensor was significantly improved and the interferences caused by ascorbic and uric acids were noticeably minimized by coating the electrode surface with a Nafion thin film

Thermal Inactivation Kinetics of Recombinant Proteins of the Lipoxygenase Pathway Related to the Synthesis of Virgin Olive Oil Volatile Compounds

The aim of this work was to characterize the thermal inactivation parameters of recombinant proteins related to the biosynthesis of virgin olive oil (VOO) volatile compounds through the lipoxygenase (LOX) pathway. Three purified LOX isoforms (Oep2LOX1, Oep1LOX2, and Oep2LOX2) and a hydroperoxide lyase (HPL) protein (OepHPL) were studied. According to their thermal inactivation parameters, recombinant Oep1LOX2 and Oep2LOX2 could be identified as the two LOX isoforms active in olive fruit crude preparations responsible for the synthesis of 13-hydroperoxides, the main substrates for the synthesis of VOO volatile compounds. Recombinant Oep2LOX1 displayed a low thermal stability, which suggests a weak actuation during the oil extraction process considering the current thermal conditions of this industrial process. In addition, recombinant OepHPL could be identified as the HPL activity in crude preparations. The thermal stability was the highest among the recombinant proteins studied, which suggests that HPL activity is not a limiting factor for the synthesis of VOO volatile compounds

Extracting the Americyl Hydration from an Americium Cationic Mixture in Solution: A Combined X‑ray Absorption Spectroscopy and Molecular Dynamics Study

Am­(VI) solution chemistry differs from that of lighter actinoids, as U, Pu, and Np, where the actinyl [AnO₂]²⁺ is the most stable form and plays an important role in nuclear fuel technology. The behavior of americium in solution shows the trend to stabilize lower oxidation states, mainly Am­(III). Riddle and co-workers recently reported the EXAFS and first XANES spectra of an americium-containing aqueous solution where the americyl species is detected in a mixture. We have developed Am³⁺–H₂O and [AmO₂]²⁺–H₂O intermolecular potentials based on quantum-mechanical calculations to carry out classical MD simulations of these two cations in water. Structural information extracted from the statistical trajectories has been used to simulate EXAFS and XANES spectra of both solutions. For the Am³⁺ case the theoretical–experimental agreement for both EXAFS and XANES spectra is satisfactory. This is not the case for the [AmO₂]²⁺ aqueous solutions. However, when an aqueous solution mixture of both cationic forms in a 55/45 [AmO₂]²⁺/Am³⁺ ratio is considered, the theoretical–experimental agreement is recovered. EXAFS and XANES spectra which would correspond to a pure [AmO₂]²⁺ aqueous solution are proposed. In the XANES case, the main features characterizing the simulated spectrum are consistent with those previously found in the experimental XANES spectra of stable [UO₂]²⁺ and [PuO₂]²⁺ in water