Overlapping Mixtures of Gaussian Processes for the data association problem

In this work we introduce a mixture of GPs to address the data association problem, i.e. to label a group of observations according to the sources that generated them. Unlike several previously proposed GP mixtures, the novel mixture has the distinct characteristic of using no gating function to determine the association of samples and mixture components. Instead, all the GPs in the mixture are global and samples are clustered following "trajectories" across input space. We use a non-standard variational Bayesian algorithm to efficiently recover sample labels and learn the hyperparameters. We show how multi-object tracking problems can be disambiguated and also explore the characteristics of the model in traditional regression settings

Rocking curve measurements revisited

The study of materials by diffraction methods started about 100 years ago with the pioneering experiment of Laue, Friedrich and Knipping, when the first X-ray diffraction patterns of single crystals were obtained (Friedrich et al., 1912). This was the beginning of a rapid development fostering many diffraction-based methods and techniques, which is still continuing. The measurement of rocking curves and the associated derived quantitative parameters, such as the ‘full width at half-maximum’ (FWHM) of the curves, has been performed since at least 1921 (Davis & Stempel, 1921) by exploiting the X-ray diffraction (XRD) properties of crystals. Since then, this has become one of the most powerful methods for the diffraction-based characterization of crystalline materials. The experimentally closely related method of X-ray diffraction imaging or X-ray diffraction topography has been used since about 1931 (Berg, 1931). Soon after World War II, the requirements of the electronics industry for the nondestructive analysis of defects in semiconductor materials like silicon and germanium (and others) boosted the improvement of these methods to their modern high-resolution variants like high-resolution X-ray diffraction and in particular high-resolution and high strain sensitivity X-ray topography (Bond & Andrus, 1952; Lang, 1957). This evolution was additionally accelerated in the late 1970s by the use of synchrotrons as dedicated X-ray sources and later on, starting in the 1990s, by the use of third-generation synchrotron sources...

Extending the honey bee venome with the antimicrobial peptide apidaecin and a protein resembling wasp antigen 5

Honey bee venom is a complex mixture of toxic proteins and peptides. In the present study we tried to extend our knowledge of the venom composition using two different approaches. First, worker venom was analysed by liquid chromatography-mass spectrometry and this revealed the antimicrobial peptide apidaecin for the first time in such samples. Its expression in the venom gland was confirmed by reverse transcription PCR and by a peptidomic analysis of the venom apparatus tissue. Second, genome mining revealed a list of proteins with resemblance to known insect allergens or venom toxins, one of which showed homology to proteins of the antigen 5 (Ag5)/Sol i 3 cluster. It was demonstrated that the honey bee Ag5-like gene is expressed by venom gland tissue of winter bees but not of summer bees. Besides this seasonal variation, it shows an interesting spatial expression pattern with additional production in the hypopharyngeal glands, the brains and the midgut. Finally, our immunoblot study revealed that both synthetic apidaecin and the Ag5-like recombinant from bacteria evoke no humoral activity in beekeepers. Also, no IgG4-based cross-reactivity was detected between the honey bee Ag5-like protein and its yellow jacket paralogue Ves v 5

Standard methods for Apis mellifera venom research

Honey bees have a sting which allows them to inject venomous substances into the body of an opponent or attacker. As the sting originates from a modified ovipositor, it only occurs in the female insect, and this is a defining feature of the bee species that belong to a subclade of the Hymenoptera called Aculeata. There is considerable interest in bee venom research, primarily because of an important subset of the human population who will develop a sometimes life threatening allergic response after a bee sting. However, the use of honey bee venom goes much further, with alleged healing properties in ancient therapies and recent research. The present paper aims to standardize selected methods for honey bee venom research. It covers different methods of venom collection, characterization and storage. Much attention was also addressed to the determination of the biological activity of the venom and its use in the context of biomedical research, more specifically venom allergy. Finally, the procedure for the assignment of new venom allergens has been presented. Las abejas meliferas tienen un aguijon que les permite inyectar sustancias venenosas en el cuerpo de un oponente o atacante. El aguijon es un ovipositor modificado que solo se manifiesta en el insecto hembra, siendo este una caracteristica que define a las especies de abejas que pertenecen al subclado de himenopteros llamada Aculeata. Hay un interes considerable en la investigacion del veneno de abeja, principalmente debido a que un porcentaje importante de la poblacion humana desarrollara una respuesta alergica - a veces mortal - a la picadura de abeja. Sin embargo, el uso del veneno de la abeja melifera abarca mucho mas, con presuntas propiedades curativas en terapias antiguas e investigaciones recientes. El presente trabajo tiene como objetivo estandarizar metodos seleccionados para la investigacion del veneno de las abejas meliferas. Cubre diferentes metodos de recoleccion, caracterizacion y almacenamiento de veneno. Tambien se presto mucha atencion a la determinacion de la actividad biologica del veneno y su uso en el contexto de la investigacion biomedica, mas especificamente la alergia al veneno. Finalmente, se ha presentado el procedimiento para la asignacion de nuevos alergenos de veneno

Thermodiffusion in multicomponent n-alkane mixtures

Compositional grading within a mixture has a strong impact on the evaluation of the pre-exploitation distribution of hydrocarbons in underground layers and sediments. Thermodiffusion, which leads to a partial diffusive separation of species in a mixture due to the geothermal gradient, is thought to play an important role in determining the distribution of species in a reservoir. However, despite recent progress, thermodiffusion is still difficult to measure and model in multicomponent mixtures. In this work, we report on experimental investigations of the thermodiffusion of multicomponent n-alkane mixtures at pressure above 30 MPa. The experiments have been conducted in space onboard the Shi Jian 10 spacecraft so as to isolate the studied phenomena from convection. For the two exploitable cells, containing a ternary liquid mixture and a condensate gas, measurements have shown that the lightest and heaviest species had a tendency to migrate, relatively to the rest of the species, to the hot and cold region, respectively. These trends have been confirmed by molecular dynamics simulations. The measured condensate gas data have been used to quantify the influence of thermodiffusion on the initial fluid distribution of an idealised one dimension reservoir. The results obtained indicate that thermodiffusion tends to noticeably counteract the influence of gravitational segregation on the vertical distribution of species, which could result in an unstable fluid column. This confirms that, in oil and gas reservoirs, the availability of thermodiffusion data for multicomponent mixtures is crucial for a correct evaluation of the initial state fluid distribution

The genomes of two key bumblebee species with primitive eusocial organization

Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation

Prevalence and mechanisms of resistance to carbapenems in Enterobacteriaceae

Objectives: To determine the point prevalence of carbapenem-non-susceptible Enterobacteriaceae (CNSE) and carbapenemase-producing Enterobacteriaceae (CPE) isolates among hospitalized patients in Belgium. Methods: Twenty-four hospital-based laboratories prospectively collected 200 non-duplicated Enterobacteriaceae isolates from clinical specimens of hospitalized patients over a 2 month period. All isolates were screened locally for decreased susceptibility to carbapenem drugs using a disc diffusion method according to CLSI interpretative criteria. CNSE strains were referred centrally for confirmation of carbapenemase by phenotypic and molecular testing. Results: From February to April 2012, 158 of the 4564 screened Enterobacteriaceae isolates were categorized as non-susceptible to carbapenems, resulting in a point prevalence of CNSE of 3.5% (95% CI: 2.9%–4.2%; range per centre: 0.5%–8.5%). Of the 125 referred CNSE isolates, 11 Klebsiella pneumoniae isolates [OXA-48 (n=7), KPC type (n=3) and NDM type (n=1)], 1 OXA-48-positive Escherichia coli isolate and 1 KPC-positive Klebsiella oxytoca isolate were detected in eight hospitals. None of the 72 carbapenem-non-susceptible Enterobacter spp. isolates were confirmed as CPE. The minimal estimated point prevalence of CPE isolates was 0.28% (13/ 4564; 95% CI: 0.13%–0.44%) overall (range per centre: 0%–1.5%). Conclusions: Despite the overall low prevalence of CNSE found in this study, the detection of CPE isolates in one-third of the participating centres raises concerns and highly suggests the spread and establishment of CPE in Belgian hospitals

European Space Agency experiments on thermodiffusion of fluid mixtures in space

Abstract.: This paper describes the European Space Agency (ESA) experiments devoted to study thermodiffusion of fluid mixtures in microgravity environment, where sedimentation and convection do not affect the mass flow induced by the Soret effect. First, the experiments performed on binary mixtures in the IVIDIL and GRADFLEX experiments are described. Then, further experiments on ternary mixtures and complex fluids performed in DCMIX and planned to be performed in the context of the NEUF-DIX project are presented. Finally, multi-component mixtures studied in the SCCO project are detailed

Sequence Diversity in the Dickeya fliC Gene: Phylogeny of the Dickeya Genus and TaqMan® PCR for 'D. solani', New Biovar 3 Variant on Potato in Europe

Worldwide, Dickeya (formerly Erwinia chrysanthemi) is causing soft rot diseases on a large diversity of crops and ornamental plants. Strains affecting potato are mainly found in D. dadantii, D. dianthicola and D. zeae, which appear to have a marked geographical distribution. Furthermore, a few Dickeya isolates from potato are attributed to D. chrysanthemi and D. dieffenbachiae. In Europe, isolates of Erwinia chrysanthemi biovar 1 and biovar 7 from potato are now classified in D. dianthicola. However, in the past few years, a new Dickeya biovar 3 variant, tentatively named ‘Dickeya solani’, has emerged as a common major threat, in particular in seed potatoes. Sequences of a fliC gene fragment were used to generate a phylogeny of Dickeya reference strains from culture collections and with this reference backbone, to classify pectinolytic isolates, i.e. Dickeya spp. from potato and ornamental plants. The reference strains of the currently recognized Dickeya species and ‘D. solani’ were unambiguously delineated in the fliC phylogram. D. dadantii, D. dianthicola and ‘D. solani’ displayed unbranched clades, while D. chrysanthemi, D. zeae and D. dieffenbachiae branched into subclades and lineages. Moreover, Dickeya isolates from diagnostic samples, in particular biovar 3 isolates from greenhouse ornamentals, formed several new lineages. Most of these isolates were positioned between the clade of ‘D. solani’ and D. dadantii as transition variants. New lineages also appeared in D. dieffenbachiae and in D. zeae. The strains and isolates of D. dianthicola and ‘D. solani’ were differentiated by a fliC sequence useful for barcode identification. A fliC TaqMan®real-time PCR was developed for ‘D. solani’ and the assay was provisionally evaluated in direct analysis of diagnostic potato samples. This molecular tool can support the efforts to control this particular phytopathogen in seed potato certification