5,523 research outputs found

    Equivalence theory for density estimation, Poisson processes and Gaussian white noise with drift

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    This paper establishes the global asymptotic equivalence between a Poisson process with variable intensity and white noise with drift under sharp smoothness conditions on the unknown function. This equivalence is also extended to density estimation models by Poissonization. The asymptotic equivalences are established by constructing explicit equivalence mappings. The impact of such asymptotic equivalence results is that an investigation in one of these nonparametric models automatically yields asymptotically analogous results in the other models.Comment: Published at http://dx.doi.org/10.1214/009053604000000012 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Leaf Detritus Processing in an Ozark Cave Stream

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    Detritus processing rates and mechanisms were investigated in an Ozark cave stream using post oak (Quercus stellata) leaf packs. The 5 g leaf packs lost ca. 30% of their dry weight within 84 days, resulting in a calculated K value of 0.05. This was an unexpectedly high rate of utilization. Diversity of invertebrates associated with the leaf packs was very low. Stygobromus ozarkensis (Amphipoda) was the only shredder. The two isopods, Caecidotea stiladactyla and Lirceus sp. were the only collectors observed other than a single species of oligochaete worm. Our data indicated that leaf detritus processing rates are virtually independent of the number of types of invertebrates associated with the leaf packs

    The Intermediate Luminosity Optical Transient SN 2010da: The Progenitor, Eruption and Aftermath of a Peculiar Supergiant High-mass X-ray Binary

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    We present optical spectroscopy, ultraviolet to infrared imaging and X-ray observations of the intermediate luminosity optical transient (ILOT) SN 2010da in NGC 300 (d=1.86 Mpc) spanning from -6 to +6 years relative to the time of outburst in 2010. Based on the light curve and multi-epoch SEDs of SN 2010da, we conclude that the progenitor of SN 2010da is a ~10-12 Msol yellow supergiant possibly transitioning into a blue loop phase. During outburst, SN 2010da had a peak absolute magnitude of M<-10.4 mag, dimmer than other ILOTs and supernova impostors. We detect multi-component hydrogen Balmer, Paschen, and Ca II emission lines in our high-resolution spectra, which indicate a dusty and complex circumstellar environment. Since the 2010 eruption, the star has brightened by a factor of ~5 and remains highly variable in the optical. Furthermore, we detect SN 2010da in archival Swift and Chandra observations as an ultraluminous X-ray source (L~6x10^{39} erg/s). We additionally attribute He II 4686 Angstrom and coronal Fe emission lines in addition to a steady X-ray luminosity of ~10^{37} erg/s to the presence of a compact companion.Comment: published; updated citations and other minor edit

    Protein Prenylation in the moss Physcomitrium patens

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    Protein prenylation is the addition of a 15 or 20 carbon lipid to a cysteine near carboxyl terminus of target proteins. Prenylation increases hydrophobicity, which facilitates membrane associations and protein-protein interaction. Protein prenylation is generally conserved among eukaryotes, and mutations in genes that carry out prenylation are lethal in animals and yeast. In plants prenylation mutations are not always lethal, but they do affect development, disease resistance, biofuel production, and drought response, among other processes of agricultural interest. To understand the evolutionary and developmental implications of plant protein prenylation, we used the sequenced, annotated, and translated genome of the moss Physcomitrium patens to search for proteins that meet minimal criteria for prenylation; specifically the presence of a sequence that includes cysteine and one of six specific amino acids at the C terminus. We then analyzed these proteins with an online prenylation prediction program to assess their likelihood of being prenylated based on additional sequence motifs. We then determined potential biological function of putative target proteins by using BLAST sequence similarity searches to identify related genes with known function. We plan to use these data to select prenylated proteins with functions of interest for in vivo studies using genetic and molecular tools to investigate their roles in plant development and environmental response. REFERENCES http://www.jbc.org/cgi/doi/10.1074/jbc.M115.673491https://ir.library.louisville.edu/uars/1051/thumbnail.jp

    Potentiometric enzyme channelling immunosensor for proteins

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    A potentiometric immunosensor for the detection of human IgG has been developed using an asymmetric, ion-selective membrane with immobilized adenosine deaminase and IgG. A protein A-alkaline phosphatase conjugate binds to the immobilized IgG, creating a bienzymatic catalytic layer. In the presence of sample IgG, the conjugate does not bind to the membrane. Instead, the intermediate in the two-step reaction (adenosine) must diffuse to the membrane surface, reducing the rate of product (ammonium) formation within the diffusion layer detected by the membrane. The immunosensor demonstrated is for the determination of IgG. A simplified model is described to predict the maximum rate enhancement for the `channeled' versus `unchanneled' reaction mechanisms.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29631/1/0000720.pd

    Destructive disinfection of infected brood prevents systemic disease spread in ant colonies

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    Social insects protect their colonies from infectious disease through collective defences that result in social immunity. In ants, workers first try to prevent infection of colony members. Here, we show that if this fails and a pathogen establishes an infection, ants employ an efficient multicomponent behaviour − &quot;destructive disinfection&quot; − to prevent further spread of disease through the colony. Ants specifically target infected pupae during the pathogen's non-contagious incubation period, relying on chemical 'sickness cues' emitted by pupae. They then remove the pupal cocoon, perforate its cuticle and administer antimicrobial poison, which enters the body and prevents pathogen replication from the inside out. Like the immune system of a body that specifically targets and eliminates infected cells, this social immunity measure sacrifices infected brood to stop the pathogen completing its lifecycle, thus protecting the rest of the colony. Hence, the same principles of disease defence apply at different levels of biological organisation

    ZOBOV: a parameter-free void-finding algorithm

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    ZOBOV (ZOnes Bordering On Voidness) is an algorithm that finds density depressions in a set of points, without any free parameters, or assumptions about shape. It uses the Voronoi tessellation to estimate densities, which it uses to find both voids and subvoids. It also measures probabilities that each void or subvoid arises from Poisson fluctuations. This paper describes the ZOBOV algorithm, and the results from its application to the dark-matter particles in a region of the Millennium Simulation. Additionally, the paper points out an interesting high-density peak in the probability distribution of dark-matter particle densities.Comment: 10 pages, 8 figures, MNRAS, accepted. Added explanatory figures, and better edge-detection methods. ZOBOV code available at http://www.ifa.hawaii.edu/~neyrinck/vobo

    Real-time reporting of baleen whale passive acoustic detections from ocean gliders

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    Author Posting. © Acoustical Society of America, 2013. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 134 (2013): 1814-1823, doi:10.1121/1.4816406.In the past decade, much progress has been made in real-time passive acoustic monitoring of marine mammal occurrence and distribution from autonomous platforms (e.g., gliders, floats, buoys), but current systems focus primarily on a single call type produced by a single species, often from a single location. A hardware and software system was developed to detect, classify, and report 14 call types produced by 4 species of baleen whales in real time from ocean gliders. During a 3-week deployment in the central Gulf of Maine in late November and early December 2012, two gliders reported over 25 000 acoustic detections attributed to fin, humpback, sei, and right whales. The overall false detection rate for individual calls was 14%, and for right, humpback, and fin whales, false predictions of occurrence during 15-min reporting periods were 5% or less. Transmitted pitch tracks—compact representations of sounds—allowed unambiguous identification of both humpback and fin whale song. Of the ten cases when whales were sighted during aerial or shipboard surveys and a glider was within 20 km of the sighting location, nine were accompanied by real-time acoustic detections of the same species by the glider within ±12 h of the sighting time.The Office of Naval Research funded this work, with additional support provided by the NOAA Fisheries Advanced Sampling Technologies Working Group via the Cooperative Institute for the North Atlantic Region

    Enhanced activation of an amino-terminally truncated isoform of the voltage-gated proton channel HVCN1 enriched in malignant B cells

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    The final published version can be found here: http://dx.doi.org/10.1073/pnas.1411390111M.C. is the recipient of a Bennett Fellowship from Leukaemia and Lymphoma Research (ref. 12002). M.A.B. is supported by a GlaxoSmithKline Oncology–Biotechnology and Biological Sciences Research Council Collaborative Awards in Science and Engineering PhD studentship. This work was supported by National Institutes of Health Grants GM087507 and GM102336 (to T.E.D.)
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