Non parametric finite translation mixtures with dependent regime

In this paper we consider non parametric finite translation mixtures. We prove that all the parameters of the model are identifiable as soon as the matrix that defines the joint distribution of two consecutive latent variables is non singular and the translation parameters are distinct. Under this assumption, we provide a consistent estimator of the number of populations, of the translation parameters and of the distribution of two consecutive latent variables, which we prove to be asymptotically normally distributed under mild dependency assumptions. We propose a non parametric estimator of the unknown translated density. In case the latent variables form a Markov chain (Hidden Markov models), we prove an oracle inequality leading to the fact that this estimator is minimax adaptive over regularity classes of densities

About the posterior distribution in hidden Markov models with unknown number of states

We consider finite state space stationary hidden Markov models (HMMs) in the situation where the number of hidden states is unknown. We provide a frequentist asymptotic evaluation of Bayesian analysis methods. Our main result gives posterior concentration rates for the marginal densities, that is for the density of a fixed number of consecutive observations. Using conditions on the prior, we are then able to define a consistent Bayesian estimator of the number of hidden states. It is known that the likelihood ratio test statistic for overfitted HMMs has a nonstandard behaviour and is unbounded. Our conditions on the prior may be seen as a way to penalize parameters to avoid this phenomenon. Inference of parameters is a much more difficult task than inference of marginal densities, we still provide a precise description of the situation when the observations are i.i.d. and we allow for $2$ possible hidden states.Comment: Published in at http://dx.doi.org/10.3150/13-BEJ550 the Bernoulli (http://isi.cbs.nl/bernoulli/) by the International Statistical Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm

Efficient semiparametric estimation and model selection for multidimensional mixtures

In this paper, we consider nonparametric multidimensional finite mixture models and we are interested in the semiparametric estimation of the population weights. Here, the i.i.d. observations are assumed to have at least three components which are independent given the population. We approximate the semiparametric model by projecting the conditional distributions on step functions associated to some partition. Our first main result is that if we refine the partition slowly enough, the associated sequence of maximum likelihood estimators of the weights is asymptotically efficient, and the posterior distribution of the weights, when using a Bayesian procedure, satisfies a semiparametric Bernstein von Mises theorem. We then propose a cross-validation like procedure to select the partition in a finite horizon. Our second main result is that the proposed procedure satisfies an oracle inequality. Numerical experiments on simulated data illustrate our theoretical results

Un décapité énigmatique sur le site gaulois de la Grande Halle d’Auvergne dans le Puy-de- Dôme (France)

Este artículo presenta el caso inédito en Galia de un cuerpo decapitado y descubierto en un contexto funerario y propone una reflexión interpretativa de este descubrimiento atípico

Les restes humains de l’âge du Fer de Roquepertuse (13) : fouilles anciennes et récentes

Le site de Roquepertuse, découvert en 1873, connut plusieurs explorations archéologiques jusqu’aux dernières qui débutèrent dans les années 1990. Sa renommée vient du fait que, pour la première fois en Gaule, la pratique des têtes coupées fut révélée par les travaux de H. de Gérin-Ricard. Tous les vestiges anthropologiques appartiennent à la tête osseuse et ont été retrouvés disloqués et fragmentés. Aucun os du squelette infra-crânien n’a été exhumé, si l’on excepte les deux sépultures de sujets périnatals. Le meilleur score offert par le frontal et la sous-représentation de la base du crâne pourraient témoigner du mode de traitement des têtes en vue de leur exposition. Les différents ensembles d’os se rapportent à au moins huit individus, six sujets de taille adulte et deux enfants d’un âge compris entre 10 et 15 ans. Certains os ont subi l’action du feu, brûlés ou chauffés, peut-être accidentellement, mais seule une mandibule semble avoir été brûlée à l’état frais. Seule la conservation tout à fait particulière des dents suggère que les crânes et les mandibules correspondants ont été exposés à l’air libre (intempérisation). Les nombreuses traces de décharnement sur os frais touchent le crâne comme la mandibule et sont identiques pour la plupart à celles rencontrées sur d’autres sites similaires. En revanche, aucun indice de perforation n’a été identifié. Données archéologiques et anthropologiques suggèrent qu’au moins quelques têtes entières ont été exposées au sein des alvéoles de quelques piliers d’un bâtiment monumental. L’évocation de têtes momifiées et de masques reste actuellement hypothétique.The Roquepertuse site, discovered in 1873, supported several archeological excavations till the last ones which began in the 1990’s. It is famous because, for the first time in Gaule, the practice of cut heads was revealed by the works of H. de Gérin-Ricard. Every anthropological remains belongs to the skull and were founded dislocated and fragmented. No bone from infracranium skeleton was uncovered, except those of the two perinatal burials. The best score is given by the frontal and the under-representation of the base of the skull may indicate the treatment of the heads to be exposed. The different sets of bones represent at least eight individuals, six with an adult stature and two juveniles from 10 to 15 years. Some bones have been exposed to fire, maybe accidentally, burned or heated, but only a mandible seems to have been burned in a fresh state. Only the very particular preservation of the teeth suggests that the corresponding skulls and mandibles have been exposed to the open air (weathering). Numerous cutmarks on fresh bone concern cranium as the mandible and are mostly identical to those encountered on other similar sites. On the other hand, no perforation index was identified. Archaeological and anthropological data suggest that at least a few whole heads have been exposed within the cavities of some pillars of a monumental building. The evocation of mummified heads and masks remains hypothetical

Protuberant Electrode Structures for New Retinal Implants

Focal stimulation of neural tissue is a challenge in retinal prosthetic devices in which the aim is to improve the spatial resolution of the stimulation and therefore increase the electrode density of the prosthetic devices. Our work intends to create a new implant able to enhance the focalisation of the stimulation signal through protuberant electrodes. These electrodes are micro fabricated on a soft polyimide substrate using classical metal electrodeposition techniques. Before proceeding with fabrication a FEM model of the electrode’s current density was done to select the best-performing structures and geometries in terms of local stimulation. Based on these models, several prototypes were fabricated and implanted in vivo into a rat’s eye to verify the adaptation to the retina tissue

Loss-of-function alleles of P2RX7 and TLR4 fail to affect the response to chemotherapy in non-small cell lung cancer

The success of anticancer chemotherapy relies at least in part on the induction of an immune response against tumor cells. Thus, tumors growing on mice that lack the pattern recognition receptor TLR4 or the purinergic receptor P2RX7 fail to respond to chemotherapy with anthracyclins or oxaliplatin in conditions in which the same neoplasms growing on immunocompetent mice would do so. Similarly, the therapeutic efficacy (measured as progression-free survival) of adjuvant chemotherapy with anthracyclins is reduced in breast cancer patients bearing loss-of-function alleles of TLR4 or P2RX7. TLR4 loss-of-function alleles also have a negative impact on the therapeutic outcome of oxaliplatin in colorectal cancer patients. Here, we report that loss-of-function TLR4 and P2RX7 alleles do not affect overall survival in non-small cell lung cancer (NSCLC) patients, irrespective of the administration and type of chemotherapy. The intrinsic characteristics of NSCLC (which near-to-always is chemoresistant and associated with poor prognosis) and/or the type of therapy that is employed to treat this malignancy (which near-to-always is based on cisplatin) may explain why two genes that affect the immune response to dying cells fail to influence the clinical progression of NSCLC patients

The Journey of SCAPs (Stem Cells from Apical Papilla), from Their Native Tissue to Grafting: Impact of Oxygen Concentration

Tissue engineering strategies aim at characterizing and at optimizing the cellular component that is combined with biomaterials, for improved tissue regeneration. Here, we present the immunoMap of apical papilla, the native tissue from which SCAPs are derived. We characterized stem cell niches that correspond to a minority population of cells expressing Mesenchymal stromal/Stem Cell (CD90, CD105, CD146) and stemness (SSEA4 and CD49f) markers as well as endothelial cell markers (VWF, CD31). Based on the colocalization of TKS5 and cortactin markers, we detected migration-associated organelles, podosomes-like structures, in specific regions and, for the first time, in association with stem cell niches in normal tissue. From six healthy teenager volunteers, each with two teeth, we derived twelve cell banks, isolated and amplified under 21 or 3% O2. We confirmed a proliferative advantage of all banks when cultured under 3% versus 21% O2. Interestingly, telomerase activity was similar to that of the highly proliferative hiPSC cell line, but unrelated to O2 concentration. Finally, SCAPs embedded in a thixotropic hydrogel and implanted subcutaneously in immunodeficient mice were protected from cell death with a slightly greater advantage for cells preconditioned at 3% O2

Mental health issues in unaccompanied refugee minors

Previous studies about unaccompanied refugee minors (URMs) showed that they are a highly vulnerable group who have greater psychiatric morbidity than the general population. This review focuses on mental health issues among URMs. Articles in databases PsycINFO, Medline and PubMed from 1998 to 2008 addressing this topic were reviewed. The literature had a considerable emphasis on the assessment of PTSD symptoms. Results revealed higher levels of PTSD symptoms in comparison to the norm populations and accompanied refugee minors. In several studies, age and female gender predicted or influenced PTSD symptoms. The existing literature only permits limited conclusions on this very hard to reach population. Future research should include the analysis of long-term outcomes, stress management and a more thorough analysis of the whole range of psychopathology. Additionally, the development of culturally sensitive norms and standardized measures for diverse ethnic groups is of great importance