Random effects compound Poisson model to represent data with extra zeros

This paper describes a compound Poisson-based random effects structure for modeling zero-inflated data. Data with large proportion of zeros are found in many fields of applied statistics, for example in ecology when trying to model and predict species counts (discrete data) or abundance distributions (continuous data). Standard methods for modeling such data include mixture and two-part conditional models. Conversely to these methods, the stochastic models proposed here behave coherently with regards to a change of scale, since they mimic the harvesting of a marked Poisson process in the modeling steps. Random effects are used to account for inhomogeneity. In this paper, model design and inference both rely on conditional thinking to understand the links between various layers of quantities : parameters, latent variables including random effects and zero-inflated observations. The potential of these parsimonious hierarchical models for zero-inflated data is exemplified using two marine macroinvertebrate abundance datasets from a large scale scientific bottom-trawl survey. The EM algorithm with a Monte Carlo step based on importance sampling is checked for this model structure on a simulated dataset : it proves to work well for parameter estimation but parameter values matter when re-assessing the actual coverage level of the confidence regions far from the asymptotic conditions.Comment: 4

A mathematical analysis of the effects of Hebbian learning rules on the dynamics and structure of discrete-time random recurrent neural networks

We present a mathematical analysis of the effects of Hebbian learning in random recurrent neural networks, with a generic Hebbian learning rule including passive forgetting and different time scales for neuronal activity and learning dynamics. Previous numerical works have reported that Hebbian learning drives the system from chaos to a steady state through a sequence of bifurcations. Here, we interpret these results mathematically and show that these effects, involving a complex coupling between neuronal dynamics and synaptic graph structure, can be analyzed using Jacobian matrices, which introduce both a structural and a dynamical point of view on the neural network evolution. Furthermore, we show that the sensitivity to a learned pattern is maximal when the largest Lyapunov exponent is close to 0. We discuss how neural networks may take advantage of this regime of high functional interest

Resistance of a steel-concrete hybrid thermal break system to low cycle fatigue under thermal actions

[EN] External insulation is the most widely used technique in Northern and Continental Europe. This technique generates thermal bridges where the building facade has some projecting element like balconies. The thermal requirements of actual standards lead to restore the continuity of the insulation at the interfaces by using thermal break systems (TBS). They are usually made of a box containing the insulation material, and a minimalist structural system able to transmit the shear force and the bending moment from the balcony to the wall. In most cases, structural elements are made of stainless steel, as it is less heat-conducting than normal steel. The paper focuses on a specific TBS, that uses shear keys and steel profiles to ensure the transfer of forces. TBS are also submitted to important horizontal cyclic shear deformations, provoked by the variations of the dimensions of the balconies due to climatic effects. The objective of the study presented in the paper is to show that significant yielding under these cyclic actions can be accepted during service life. First experimental cyclic loading tests have been performed in order to characterize the behaviour of the TBS, as well as its fatigue strength. Then the loading has been defined on the basis of the database of the ECA&D, the European Climate Assessment and Dataset. Finally, the fatigue resistance of the system has been verified. It is shown that the developed TBS can resist to fatigue loading for large lengths of balconies, while exhibiting significant yielding during service life.The authors gratefully acknowledge financial support by the ANR (Agence Nationale de la Recherche, France) through the project LabCom ANR B-HYBRID.Le Gac, B.; Keo, P.; Somja, H.; Palas, F. (2018). Resistance of a steel-concrete hybrid thermal break system to low cycle fatigue under thermal actions. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 709-716. https://doi.org/10.4995/ASCCS2018.2018.6990OCS70971

Anti-angiogenic VEGFAxxxb transcripts are not expressed in the medio-basal hypothalamus of the seasonal sheep

Source at https://doi.org/10.1371/journal.pone.0197123.This study investigated Vegfa expression in the pars tuberalis (PT) of the pituitary and medio-basal hypothalamus (MBH) of sheep, across seasons and reproductive states. It has recently been proposed that season impacts alternative splicing of Vegfa mRNA in the PT, which shifts the balance between angiogenic VEGFAxxx and anti-angiogenic VEGFAxxxb isoforms (with xxx the number of amino acids of the mature VEGFA proteins) to modulate seasonal breeding. Here, we used various RT-PCR methodologies and analysis of RNAseq datasets to investigate seasonal variation in expression and splicing of the ovine Vegfa gene. Collectively, we identify 5 different transcripts for Vegfa within the ewe PT/MBH, which correspond to splicing events previously described in mouse and human. All identified transcripts encode angiogenic VEGFAxxx isoforms, with no evidence for alternative splicing within exon 8. These findings led us to investigate in detail how “Vegfaxxxb-like” PCR products could be generated by RT-PCR and misidentified as endogenous transcripts, in sheep and human HEK293 cells. In conclusion, our findings do not support the existence of anti-angiogenic VEGFAxxxb isoforms in the ovine PT/MBH and shed new light on the interpretation of prior studies, which claimed to identify Vegfaxxxb isoforms by RT-PCR

Defeating ISO9797-1 MAC Algo 3 by Combining Side-Channel and Brute Force Techniques

Side-channel analysis is a well-known and efficient hardware technique to recover embedded secrets in microprocessors. Over the past years, the state-of-the-art side-channel attacks has significantly increased, leading to a myriad of vulnerability paths that secure codes must withstand. Nowadays most of the attacks target the cryptographic algorithms, but very few exploit the cryptographic protocol. In this paper, we present a new attack that exploits the information exchange at the cryptographic protocol level in order to disclose the secret key. This attack is applicable to the MAC calculations standardized in ISO/IEC 9797-1 especially the MAC algorithm 3 with the DES function. This protocol is spread in secure products nowadays, this is the case typically for some EMV implementations. By using a side-channel technique combined with a reasonable brute force effort, we show that the secret key can be fully retrieved even though the DES implementation seems to be well-protected against side-channel attacks

Relação entre o índice de massa corporal e a prevalência de cárie em pacientes pediátricos

Objetivo: Rever a literatura científica atual sobre a relação entre o índice de massa corporal e a prevalência da cárie dentária em crianças de idade escolar. Métodos: Pesquisa bibliográfica de artigos científicos publicados nas bases de dados eletrónicas: PubMed, Web of Science e B-On. Foram utilizados termos de pesquisa em combinação: dental caries, BMI, children, pediatric patient, obesity, e saliva. A seleção dos artigos foi realizada através da aplicação de critérios de inclusão e exclusão. Foram selecionados 64 artigos para a elaboração desta revisão. Tópico abordado: Não existindo uma relação direta e indubitável entre a cárie dentária e a obesidade nas crianças, os Médicos Dentistas que fazem o atendimento destes pacientes devem de agir como agentes de Saúde Pública alertando as crianças e os seus responsáveis para os riscos e implicações que o sobrepeso e a obesidade infantis representam para a qualidade de vida, a saúde oral e geral das crianças.Objectives: To review the current scientific literature on the relationship between the body mass index and the prevalence of dental caries in school-aged children. Methods: Bibliographic research of scientific articles in the electronic database PubMed, Web of Science and B-On. Combined search terms were used: dental caries, BMI, children, pediatric patient, obesity and saliva. The selection of articles was made by applying inclusion and exclusion criteria. Sixty four articles were selected for the development of this narrative review. Topic covered: Since there is no direct and incontestable relationship between dental caries and obesity in children, the dentists who treat these patients must act as public health agents, alerting children and their guardians about risks and implications that overweight and obesity in children pose to children's oral and general health

Suivi scientifique de vingt-sept régénérations naturelles de chêne sessile et de hêtre en Ardenne: retour d'expérience

National audienceRégénérer naturellement le chêne apparaît très délicat en Ardenne et cela se traduit déjà par un déficit marqué de jeunes chênes au niveau régional. Afin de rechercher des solutions sylvicoles à ce problème, vingt-sept régénérations naturelles de hêtre et de chêne ont été suivies entre 2007 et 2011. L’analyse montre clairement les besoins en lumière des chênes par rapport aux hêtres et, surtout, l’importance d’effectuer des nettoiements afin de réduire les effets de la compétition des hêtres sur les chênes