1,539 research outputs found
Self-consistent simulation of quantum shot noise in nanoscale electron devices
An approach for studying shot noise in mesoscopic systems that explicitly includes the Coulomb interaction among electrons, by self-consistently solving the Poisson equation, is presented. As a test, current fluctuations on a standard resonant tunneling diode are simulated in agreement with previous predictions and experimental results. The present approach opens a new path for the simulation of nanoscale electron devices, where pure quantum mechanical and Coulomb blockade phenomena coexist
The secreted proteins of Achlya hypogyna and Thraustotheca clavata identify the ancestral oomycete secretome and reveal gene acquisitions by horizontal gene transfer
This is the final version. Available on open access from Oxford University Press via the DOI in this recordSaprotrophic and parasitic microorganisms secrete proteins into the environment to breakdown macromolecules and obtain nutrients. The molecules secreted are collectively termed the "secretome" and the composition and function of this set of proteins varies depending on the ecology, life cycle, and environment of an organism. Beyond the function of nutrient acquisition, parasitic lineages must also secrete molecules to manipulate their host. Here, we use a combination of de novo genome and transcriptome sequencing and bioinformatic identification of signal peptides to identify the putative secreted proteome of two oomycetes, the facultative parasite Achlya hypogyna and free-living Thraustotheca clavata. By comparing the secretomes of these saprolegnialean oomycetes with that of eight other oomycetes, we were able to characterize the evolution of this protein set across the oomycete clade. These species span the last common ancestor of the two major oomycete families allowing us to identify the ancestral secretome. This putative ancestral secretome consists of at least 84 gene families. Only 11 of these gene families are conserved across all 10 secretomes analyzed and the two major branches in the oomycete radiation. Notably, we have identified expressed elicitin-like effector genes in the saprotrophic decomposer, T. clavata. Phylogenetic analyses show six novel horizontal gene transfers to the oomycete secretome from bacterial and fungal donor lineages, four of which are specific to the Saprolegnialeans. Comparisons between free-living and pathogenic taxa highlight the functional changes of oomycete secretomes associated with shifts in lifestyle.University of Rhode Island College of the Environment and Life SciencesU.S. Department of AgricultureNational Institutes of Health (NIH)National Science FoundationDivision of Biology and Medicine, Brown Universit
Molecular characterisation of viruses from Kiwifruit
In 2003 Apple stem grooving virus was discovered in Actinidia accessions from China, being held in quarantine in Auckland. Subsequent examination of kiwifruit germplasm from the same source has detected several additional viruses, including a ~300 nm rigid rod related to Ribgrass mosaic virus (Tobamovirus), a 700-750 nm flexuous virus related to Citrus leaf blotch virus (Flexiviridae) and a novel vitivirus. Currently these viruses have not been reported from commercial kiwifruit crops in New Zealand or elsewhere. The biological properties of the viruses from kiwifruit and their phylogenetic relationships with similar viruses from other plants will be described, and the possible implications for the international movement of Actinidia germplasm are discussed
Les avatars de lâinquisiteur ou la fonction de juge ecclĂ©siastique Ă la fin du Moyen Ăge
En matiĂšre de foi, les juges ne sont pas toujours ce que lâon croit et lâhabit ne fait pas forcĂ©ment lâinquisiteur. Un juge peut mĂȘme en cacher un autre. Quand on parle dâinquisitio, ou inquisition, câest dâabord pour Ă©voquer une procĂ©dure dâenquĂȘte et dâenregistrement de tĂ©moignagesâ. DĂšs la fin du xiie siĂšcle, elle sâest imposĂ©e dans la justice ecclĂ©siastiqueâ; elle fut en premier lieu le fait des Ă©vĂȘques, juges ordinaires, puis, Ă partir de 1231, de dĂ©lĂ©guĂ©s extraordinaires de la papautĂ© q..
Learning to stand with sensorimotor delays generalizes across directions and from hand to leg effectors
Humans receive sensory information from the past, requiring the brain to overcome delays to perform daily motor skills such as standing upright. Because delays vary throughout the body and change over a lifetime, it would be advantageous to generalize learned control policies of balancing with delays across contexts. However, not all forms of learning generalize. Here, we use a robotic simulator to impose delays into human balance. When delays are imposed in one direction of standing, participants are initially unstable but relearn to balance by reducing the variability of their motor actions and transfer balance improvements to untrained directions. Upon returning to normal standing, aftereffects from learning are observed as small oscillations in control, yet they do not destabilize balance. Remarkably, when participants train to balance with delays using their hand, learning transfers to standing with the legs. Our findings establish that humans use experience to broadly update their neural control to balance with delays.</p
Revisiting a pollen-transmitted ilarvirus previously associated with angular mosaic of grapevine
We report the characterization of a novel tri-segmented RNA virus infecting Mercurialis annua, a common crop weed and model species in plant science. The virus, named "Mercurialis latent virus" (MeLaV) was first identified in a mixed infection with the recently described Mercurialis orthotospovirus 1 (MerV1) on symptomatic plants grown in glasshouses in Lausanne (Switzerland). Both viruses were found to be transmitted by Thrips tabaci, which presumably help the inoculation of infected pollen in the case of MeLaV. Complete genome sequencing of the latter revealed a typical ilarviral architecture and close phylogenetic relationship with members of the Ilarvirus subgroup 1. Surprisingly, a short portion of MeLaV replicase was found to be identical to the partial sequence of grapevine angular mosaic virus (GAMV) reported in Greece in the early 1990s. However, we have compiled data that challenge the involvement of GAMV in angular mosaic of grapevine, and we propose alternative causal agents for this disorder. In parallel, three highly-conserved MeLaV isolates were identified in symptomatic leaf samples in The Netherlands, including a herbarium sample collected in 1991. The virus was also traced in diverse RNA sequencing datasets from 2013-2020, corresponding to transcriptomic analyses of M. annua and other plant species from five European countries, as well as metaviromics analyses of bees in Belgium. Additional hosts are thus expected for MeLaV, yet we argue that infected pollen grains have likely contaminated several sequencing datasets and may have caused the initial characterization of MeLaV as GAMV
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Efficient maximum likelihood pedigree reconstruction
A simple and efficient algorithm is presented for finding a maximum likelihood pedigree using microsatellite (STR) genotype information on a complete sample of related individuals. The computational complexity of the algorithm is at worst (O(n32n)), where n is the number of individuals. Thus it is possible to exhaustively search the space of all pedigrees of up to thirty individuals for one that maximizes the likelihood. A priori age and sex information can be used if available, but is not essential. The algorithm is applied in a simulation study, and to some real data on humans
Quantitative backscattered electron imaging of bone using a thermionic or a field emission electron source
Quantitative backscattered electron imaging is an established method to map mineral content distributions in bone and to determine the bone mineralization density distribution (BMDD). The method we applied was initially validated for a scanning electron microscope (SEM) equipped with a tungsten hairpin cathode (thermionic electron emission) under strongly defined settings of SEM parameters. For several reasons, it would be interesting to migrate the technique to a SEM with a field emission electron source (FE-SEM), which, however, would require to work with different SEM parameter settings as have been validated for DSM 962. The FE-SEM has a much better spatial resolution based on an electron source size in the order of several 100 nanometers, corresponding to an about 105 to 106 times smaller source area compared to thermionic sources. In the present work, we compare BMDD between these two types of instruments in order to further validate the methodology. We show that a transition to higher pixel resolution (1.76, 0.88, and 0.57 Όm) results in shifts of the BMDD peak and BMDD width to higher values. Further the inter-device reproducibility of the mean calcium content shows a difference of up to 1 wt% Ca, while the technical variance of each device can be reduced to ±0.17 wt% Ca. Bearing in mind that shifts in calcium levels due to diseases, e.g., high turnover osteoporosis, are often in the range of 1 wt% Ca, both the bone samples of the patients as well as the control samples have to be measured on the same SEM device. Therefore, we also constructed new reference BMDD curves for adults to be used for FE-SEM data comparison
4,4âČ-Dibromo-2-nitroÂbiphenÂyl
The title compound, C12H7Br2NO2, a biphenyl derivative, displays a twisted conformation with the two benzene rings making a dihedral angle of 55.34â
(14)°. The dihedral angle between the nitro group and its parent benzene ring is 26.8â
(2)°. The crystal structure is stabilized by interÂmolecular CâHâŻBr and CâHâŻO interÂactions, which lead to the formation of chains propagating along the c-axis direction
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