Adapting heterogeneous ensembles with particle swarm optimization for video face recognition

In video-based face recognition applications, matching is typically performed by comparing query samples against biometric models (i.e., an individual’s facial model) that is designed with reference samples captured during an enrollment process. Although statistical and neural pattern classifiers may represent a flexible solution to this kind of problem, their performance depends heavily on the availability of representative reference data. With operators involved in the data acquisition process, collection and analysis of reference data is often expensive and time consuming. However, although a limited amount of data is initially available during enrollment, new reference data may be acquired and labeled by an operator over time. Still, due to a limited control over changing operational conditions and personal physiology, classification systems used for video-based face recognition are confronted to complex and changing pattern recognition environments. This thesis concerns adaptive multiclassifier systems (AMCSs) for incremental learning of new data during enrollment and update of biometric models. To avoid knowledge (facial models) corruption over time, the proposed AMCS uses a supervised incremental learning strategy based on dynamic particle swarm optimization (DPSO) to evolve a swarm of fuzzy ARTMAP (FAM) neural networks in response to new data. As each particle in a FAM hyperparameter search space corresponds to a FAM network, the learning strategy adapts learning dynamics by co-optimizing all their parameters – hyperparameters, weights, and architecture – in order to maximize accuracy, while minimizing computational cost and memory resources. To achieve this, the relationship between the classification and optimization environments is studied and characterized, leading to these additional contributions. An initial version of this DPSO-based incremental learning strategy was applied to an adaptive classification system (ACS), where the accuracy of a single FAM neural network is maximized. It is shown that the original definition of a classification system capable of supervised incremental learning must be reconsidered in two ways. Not only must a classifier’s learning dynamics be adapted to maintain a high level of performance through time, but some previously acquired learning validation data must also be used during adaptation. It is empirically shown that adapting a FAM during incremental learning constitutes a type III dynamic optimization problem in the search space, where the local optima values and their corresponding position change in time. Results also illustrate the necessity of a long term memory (LTM) to store previously acquired data for unbiased validation and performance estimation. The DPSO-based incremental learning strategy was then modified to evolve the swarm (or pool) of FAM networks within an AMCS. A key element for the success of ensembles is tackled: classifier diversity. With several correlation and diversity indicators, it is shown that genoVIII type (i.e., hyperparameters) diversity in the optimization environment is correlated with classifier diversity in the classification environment. Following this result, properties of a DPSO algorithm that seeks to maintain genotype particle diversity to detect and follow local optima are exploited to generate and evolve diversified pools of FAMclassifiers. Furthermore, a greedy search algorithm is presented to perform an efficient ensemble selection based on accuracy and genotype diversity. This search algorithm allows for diversified ensembles without evaluating costly classifier diversity indicators, and selected ensembles also yield accuracy comparable to that of reference ensemble-based and batch learning techniques, with only a fraction of the resources. Finally, after studying the relationship between the classification environment and the search space, the objective space of the optimization environment is also considered. An aggregated dynamical niching particle swarm optimization (ADNPSO) algorithm is presented to guide the FAM networks according two objectives: FAM accuracy and computational cost. Instead of purely solving a multi-objective optimization problem to provide a Pareto-optimal front, the ADNPSO algorithm aims to generate pools of classifiers among which both genotype and phenotype (i.e., objectives) diversity are maximized. ADNPSO thus uses information in the search spaces to guide particles towards different local Pareto-optimal fronts in the objective space. A specialized archive is then used to categorize solutions according to FAMnetwork size and then capture locally non-dominated classifiers. These two components are then integrated to the AMCS through an ADNPSO-based incremental learning strategy. The AMCSs proposed in this thesis are promising since they create ensembles of classifiers designed with the ADNPSO-based incremental learning strategy and provide a high level of accuracy that is statistically comparable to that obtained through mono-objective optimization and reference batch learning techniques, and yet requires a fraction of the computational cost

Increased sensitivity to iron deficiency in Arabidopsis thaliana overaccumulating nicotianamine

Nicotianamine (NA) is a non-protein amino acid derivative synthesized from S-adenosyl L-methionine able to bind several metal ions such as iron, copper, manganese, zinc, or nickel. In plants, NA appears to be involved in iron availability and is essential for the plant to complete its biological cycle. In graminaceous plants, NA is also the precursor in the biosynthesis of phytosiderophores. Arabidopsis lines accumulating 4- and 100-fold more NA than wild-type plants were used in order to evaluate the impact of such an NA overaccumulation on iron homeostasis. The expression of iron-regulated genes including the IRT1/FRO2 iron uptake system is highly induced at the transcript level under both iron-sufficient and iron-deficient conditions. Nevertheless, NA overaccumulation does not interfere with the iron uptake mechanisms since the iron levels are similar in the NA-overaccumulating line and wild-type plants in both roots and leaves under both sufficient and deficient conditions. This observation also suggests that the translocation of iron from the root to the shoot is not affected in the NA-overaccumulating line. However, NA overaccumulation triggers an enhanced sensitivity to iron starvation, associated with a decrease in iron availability. This study draws attention to a particular phenotype where NA in excess paradoxically leads to iron deficiency, probably because of an increase of the NA apoplastic pool sequestering iron. This finding strengthens the notion that extracellular NA in the apoplast could be a major checkpoint to control plant iron homeostasis

European recommendations on practices in pediatric neuroradiology: consensus document from the European Society of Neuroradiology (ESNR), European Society of Paediatric Radiology (ESPR) and European Union of Medical Specialists Division of Neuroradiology (UEMS)

Pediatric neuroradiology is a subspecialty within radiology, with possible pathways to train within the discipline from neuroradiology or pediatric radiology. Formalized pediatric neuroradiology training programs are not available in most European countries. We aimed to construct a European consensus document providing recommendations for the safe practice of pediatric neuroradiology. We particularly emphasize imaging techniques that should be available, optimal site conditions and facilities, recommended team requirements and specific indications and protocol modifications for each imaging modality employed for pediatric neuroradiology studies. The present document serves as guidance to the optimal setup and organization for carrying out pediatric neuroradiology diagnostic and interventional procedures. Clinical activities should always be carried out in full agreement with national provisions and regulations. Continued education of all parties involved is a requisite for preserving pediatric neuroradiology practice at a high level

R.E.D. Server: a web service for deriving RESP and ESP charges and building force field libraries for new molecules and molecular fragments

R.E.D. Server is a unique, open web service, designed to derive non-polarizable RESP and ESP charges and to build force field libraries for new molecules/molecular fragments. It provides to computational biologists the means to derive rigorously molecular electrostatic potential-based charges embedded in force field libraries that are ready to be used in force field development, charge validation and molecular dynamics simulations. R.E.D. Server interfaces quantum mechanics programs, the RESP program and the latest version of the R.E.D. tools. A two step approach has been developed. The first one consists of preparing P2N file(s) to rigorously define key elements such as atom names, topology and chemical equivalencing needed when building a force field library. Then, P2N files are used to derive RESP or ESP charges embedded in force field libraries in the Tripos mol2 format. In complex cases an entire set of force field libraries or force field topology database is generated. Other features developed in R.E.D. Server include help services, a demonstration, tutorials, frequently asked questions, Jmol-based tools useful to construct PDB input files and parse R.E.D. Server outputs as well as a graphical queuing system allowing any user to check the status of R.E.D. Server jobs

Increased risk of miscarriage among women experiencing physical or sexual intimate partner violence during pregnancy in Guatemala City, Guatemala: cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Violence against women by their male intimate partners (IPV) during pregnancy may lead to negative pregnancy outcomes. We examined the role of IPV as a potential risk factor for miscarriage in Guatemala. Our objectives were: (1) To describe the magnitude and pattern of verbal, physical and sexual violence by male intimate partners in the last 12 months (IPV) in a sample of pregnant Guatemalans; (2) To evaluate the influence of physical or sexual IPV on miscarriage as a pregnancy outcome.</p> <p>Methods</p> <p>All pregnant women reporting to the maternity of a major tertiary care public hospital in Guatemala City from June 1st to September 30th, 2006 were invited to participate in this cross-sectional study. The admitting physician assessed occurrence of miscarriage, defined as involuntary pregnancy loss up to and including 28 weeks gestation. Data on IPV, social and demographic characteristics, risk behaviours, and medical history were collected by interviewer-administered questionnaire. Laboratory testing was performed for HIV and syphilis. The relationship between IPV and miscarriage was assessed through multivariable logistic regression.</p> <p>Results</p> <p>IPV affected 18% of the 1897 pregnant Guatemalan women aged 15-47 in this sample. Verbal IPV was most common (16%), followed by physical (10%) and sexual (3%) victimisation. Different forms of IPV were often co-prevalent. Miscarriage was experienced by 10% of the sample (<it>n </it>= 190). After adjustment for potentially confounding factors, physical or sexual victimisation by a male intimate partner in the last 12 months was significantly associated with miscarriage (ORadj 1.1 to 2.8). Results were robust under a range of analytic assumptions.</p> <p>Conclusions</p> <p>Physical and sexual IPV is associated with miscarriage in this Guatemalan facility-based sample. Results cohere well with findings from population-based surveys. IPV should be recognised as a potential cause of miscarriage. Reproductive health services should be used to screen for spousal violence and link to assistance.</p

An Indo-Pacifc coral spawning database

The discovery of multi-species synchronous spawning of scleractinian corals on the Great Barrier Reef in the 1980s stimulated an extraordinary effort to document spawning times in other parts of the globe. Unfortunately, most of these data remain unpublished which limits our understanding of regional and global reproductive patterns. The Coral Spawning Database (CSD) collates much of these disparate data into a single place. The CSD includes 6178 observations (3085 of which were unpublished) of the time or day of spawning for over 300 scleractinian species in 61 genera from 101 sites in the Indo-Pacific. The goal of the CSD is to provide open access to coral spawning data to accelerate our understanding of coral reproductive biology and to provide a baseline against which to evaluate any future changes in reproductive phenology

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570