Bayesian Bivariate Image Analysis with Application to Dual Autoradiography

We present a Bayesian bivariate image model and apply it to a study that was designed to investigate the relationship between hypoxia and angiogenesis in an animal tumor model. Two radiolabeled tracers (one measuring angio- genesis, the other measuring hypoxia) were simultaneously injected into the animals, the tumors removed and autoradiographic images of the tracer concentrations were obtained. We model correlation between tracers with a mixture of bivariate normal distributions and the spatial correlation inherent in the images by means of the celebrated Potts model. Although the Potts model is typically used for image segmentation, we use it solely as a device to account for spatial correlation. The number of classes in the model is assumed un- known and is estimated via reversible jump MCMC, marginalizing over the number of classes for posterior inference. We present the model and estimation method using set theory notation which will assist us in introducing a novel reallocation scheme used in the reversible jump proposals. We also estimate the spatial regularization parameter in the Potts model prior. Through a simulation study, we show that it is necessary to account for both the spatial correlation and the correlation between the two tracers

Adaptation au niveau de disponibilité en azote, en communautés herbacées : deux exemples : Anthroxanthum odoratum L. et Arrhenatherum elatius (L.) J. et C. Prest var. vulgare Koch

Les relations entre la croissance et la disponibilité en azote de trois populations d'#A. odoratum# et de trois populations d'#A. elatius# sont étudiés en conditions naturelles et semi-controlées. Les deux espéces et leurs populations diffèrent par leur efficacité d'utilisation de l'azote pour la croissance et par leur tolérance à l'ombrage. Les résultats sont interprétés en termes d'avantages adaptatifs des deux espéces dans leurs milieux respectifs. (Résumé d'auteur

Strangeness S=−2S=-2 baryon-baryon interactions in relativistic chiral effective field theory

We study the strangeness $S=-2$ baryon-baryon interactions in relativistic chiral effective field theory at leading order. Among the 15 relevant low energy constants, eight of them are determined by fitting to the state of the art lattice QCD data of the HAL QCD Collaboration (with $m_\pi=146$ MeV), and the rest are either taken from the study of the $S=-1$ hyperon-nucleon systems, assuming strict SU(3) flavor symmetry, or temporarily set equal to zero. Using the so-obtained low energy constants, we extrapolate the results to the physical point, and show that they are consistent with the available experimental scattering data. Furthermore, we demonstrate that the $\Lambda\Lambda$ and $\Xi N$ phase shifts near the $\Xi N$ threshold are very sensitive to the lattice QCD data fitted, to the pion mass, and to isospin symmetry breaking effects. As a result, any conclusion drawn from lattice QCD data at unphysical pion masses (even close to the physical point) should be taken with caution. Our results at the physical point, similar to the lattice QCD data, show that a resonance/quasi-bound state may appear in the $I=0$ $\Lambda\Lambda$/$\Xi N$ channel.Comment: 20 pages, 8 figure

Lack of involvement of lipocortin 1 in dexamethasone suppression of IL-1 release

The annexin lipocortin 1 is reported to mediate some anti-inflammatory effects of glucocorticoids, but the mechanisms of this mediation are incompletely understood. The involvement of lipocortin 1 in glucocorticoid inhibition of monocyte interleukin 1β (IL-1β) release has been investigated. Treatment of peripheral blood monocytes with 2 μg/ml lipopolysaccharide potently increased IL–1β release (p = 0.001) and dexamethasone (10−7 M) significantly reduced both resting and stimulated IL-1β release (p = 0.009). A neutralizing monoclonal antibody to lipocortin 1 (0.5–50.0 μg/ml) was unable to inhibit this effect and recombinant lipocortin 1 (2 × 10−6 M) and 188aa lipocortin 1 fragment (10−8−10−6 M) had no effect. It is concluded that lipocortin 1 is not involved in the inhibition of monocyte IL-1β release by glucocorticoids

Efficient Exploration of Microstructure-Property Spaces via Active Learning

In materials design, supervised learning plays an important role for optimization and inverse modeling of microstructure-property relations. To successfully apply supervised learning models, it is essential to train them on suitable data. Here, suitable means that the data covers the microstructure and property space sufficiently and, especially for optimization and inverse modeling, that the property space is explored broadly. For virtual materials design, typically data is generated by numerical simulations, which implies that data pairs can be sampled on demand at arbitrary locations in microstructure space. However, exploring the space of properties remains challenging. To tackle this problem, interactive learning techniques known as active learning can be applied. The present work is the first that investigates the applicability of the active learning strategy query-by-committee for an efficient property space exploration. Furthermore, an extension to active learning strategies is described, which prevents from exploring regions with properties out of scope (i.e., properties that are physically not meaningful or not reachable by manufacturing processes)

Prevalence and molecular characterization of Rickettsia spp. from wild small mammals in public parks and urban areas of Bangkok Metropolitan, Thailand

Rural areas usually show a higher prevalence of rickettsial infection than urban areas. However, information on the rickettsial infection status in urban settings (e.g., built-up areas and city parks) is still limited, particularly in the Bangkok metropolitan area. In this study, we performed a molecular rickettsial survey of spleen samples of small mammals caught in public parks and built-up areas of Bangkok. Out of 198 samples, the Rattus rattus complex was found to be most prevalent. The amplification of rickettsial gltA fragment gene (338 bp) by nested PCR assay revealed positive results in four samples, yielding a low prevalence of infection of 2.02%. DNA sequencing results confirmed that three samples were matched with Rickettsia typhi, and one was identified as R. felis. It is noteworthy that this is the first report of the occurrence of R. felis DNA in rodents in Southeast Asia

Risk factors analysis for neglected human rickettsioses in rural communities in Nan province, Thailand: a community-based observational study along a landscape gradient.

In this study, we estimated exposure for Scrub typhus (STG), Typhus (TG) and Spotted fever groups (SFG) rickettsia using serology at a fine scale (a whole sub-district administration level) of local communities in Nan Province, Thailand. Geographical characteristics of the sub-district were divided into two landscape types: lowland agricultural area in an urbanized setting (lowland-urbanized area) and upland agricultural area located close to a protected area of National Park (upland-forested area). This provided an ideal contrast between the two landscapes with low and high levels of human-altered habitats to study in differences in disease ecology. In total, 824 serum samples of participants residing in the eight villages were tested by screening IgG ELISA, and subsequently confirmed by the gold standard IgG Immunofluorescent Assay (IFA). STG and TG IgG positivity were highest with seroprevalence of 9.8% and 9.0%, respectively; whereas SFG positivity was lower at 6.9%. Inhabitants from the villages located in upland-forested area demonstrated significantly higher STG exposure, compared to those villages in the lowland-urbanized area (chi-square = 51.97, p < 0.0001). In contrast, TG exposure was significantly higher in those villagers living in lowland-urbanized area (chi-square = 28.26, p < 0.0001). In addition to the effect of landscape types, generalized linear model (GLM) analysis identified socio-demographic parameters, i.e., gender, occupation, age, educational level, domestic animal ownership (dog, cattle and poultry) as influential factors to explain the level of rickettsial exposure (antibody titers) in the communities. Our findings raise the public health awareness of rickettsiosis as a cause of undiagnosed febrile illness in the communities