459 research outputs found

    Partial Homology Relations - Satisfiability in terms of Di-Cographs

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    Directed cographs (di-cographs) play a crucial role in the reconstruction of evolutionary histories of genes based on homology relations which are binary relations between genes. A variety of methods based on pairwise sequence comparisons can be used to infer such homology relations (e.g.\ orthology, paralogy, xenology). They are \emph{satisfiable} if the relations can be explained by an event-labeled gene tree, i.e., they can simultaneously co-exist in an evolutionary history of the underlying genes. Every gene tree is equivalently interpreted as a so-called cotree that entirely encodes the structure of a di-cograph. Thus, satisfiable homology relations must necessarily form a di-cograph. The inferred homology relations might not cover each pair of genes and thus, provide only partial knowledge on the full set of homology relations. Moreover, for particular pairs of genes, it might be known with a high degree of certainty that they are not orthologs (resp.\ paralogs, xenologs) which yields forbidden pairs of genes. Motivated by this observation, we characterize (partial) satisfiable homology relations with or without forbidden gene pairs, provide a quadratic-time algorithm for their recognition and for the computation of a cotree that explains the given relations

    Injective split systems

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    A split system S\mathcal S on a finite set XX, ∣X∣≥3|X|\ge3, is a set of bipartitions or splits of XX which contains all splits of the form {x,X−{x}}\{x,X-\{x\}\}, x∈Xx \in X. To any such split system S\mathcal S we can associate the Buneman graph B(S)\mathcal B(\mathcal S) which is essentially a median graph with leaf-set XX that displays the splits in S\mathcal S. In this paper, we consider properties of injective split systems, that is, split systems S\mathcal S with the property that medB(S)(Y)≠medB(S)(Y′)\mathrm{med}_{\mathcal B(\mathcal S)}(Y) \neq \mathrm{med}_{\mathrm B(\mathcal S)}(Y') for any 3-subsets Y,Y′Y,Y' in XX, where medB(S)(Y)\mathrm {med}_{\mathcal B(\mathcal S)}(Y) denotes the median in B(S)\mathcal B(\mathcal S) of the three elements in YY considered as leaves in B(S)\mathcal B(\mathcal S). In particular, we show that for any set XX there always exists an injective split system on XX, and we also give a characterization for when a split system is injective. We also consider how complex the Buneman graph B(S)\mathcal B(\mathcal S) needs to become in order for a split system S\mathcal S on XX to be injective. We do this by introducing a quantity for ∣X∣|X| which we call the injective dimension for ∣X∣|X|, as well as two related quantities, called the injective 2-split and the rooted-injective dimension. We derive some upper and lower bounds for all three of these dimensions and also prove that some of these bounds are tight. An underlying motivation for studying injective split systems is that they can be used to obtain a natural generalization of symbolic tree maps. An important consequence of our results is that any three-way symbolic map on XX can be represented using Buneman graphs.Comment: 22 pages, 3 figure

    Preparation And Characterization Of Composite Hollow Fiber Reverse Osmosis Membranes By Plasma Polymerization. 1. Design Of Plasma Reactor And Operational Parameters

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    Composite hollow fiber reverse osmosis membranes were prepared by depositing a thin layer (10-50 nm) of plasma polymers on hollow fibers with porous walls (made of polysulfone). The coating was carried out in a semicontinuous manner with six strands of substrate fibers. Operational parameters which influence reverse osmosis characteristics of composite membranes were investigated. © 1984, American Chemical Society. All rights reserved

    Sub surface damage measurements based on short coherent interferometry

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    During the manufacturing process of glass lenses, especially the grinding step, it is important to control such parameters as shape and sub-surface damage (SSD) with high accuracy which essentially influences the duration and costs of the subsequent polishing process. Typically used methods measure the parameters only separately and suffer from limited resolution. Especially, the nondestructive measurement of SSD is a challenge for the metrology of grinded surfaces. In order to detect these parameters simultaneously, the scanning short-coherence interferometer, a method very similar to optical coherence tomography, is setup and tested at Aalen University. The lens under test is mounted on a rotation stage which can be translated in lateral direction. The sensor beam of the interferometer is focused onto the sample and can be moved along the axial direction. The precision of the depth measurements is 0.25 µm, lateral positioning accuracy is 2 µm and lateral resolution is 4 µm. The system is able to measure SSD at several positions on a lens within 10 min inside the optical workshop

    Porosity characterization of selected nanoporous solids

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    Health Literacy and Medication Practices in Senior Housing Residents

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    Objective: To conduct a descriptive analysis of health literacy, knowledge of prescribed medications, and methods of administering medications in a cohort of senior housing residents.https://scholarworks.uvm.edu/comphp_gallery/1027/thumbnail.jp

    Oculomotor function in frontotemporal lobar degeneration, related disorders and Alzheimer's disease

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    Frontotemporal lobar degeneration (FTLD) often overlaps clinically with corticobasal syndrome (CBS) and progressive supranuclear palsy (PSP), both of which have prominent eye movement abnormalities. To investigate the ability of oculomotor performance to differentiate between FTLD, Alzheimer's disease, CBS and PSP, saccades and smooth pursuit were measured in three FTLD subtypes, including 24 individuals with frontotemporal dementia (FTD), 19 with semantic dementia (SD) and six with progressive non-fluent aphasia (PA), as compared to 28 individuals with Alzheimer's disease, 15 with CBS, 10 with PSP and 27 control subjects. Different combinations of oculomotor abnormalities were identified in all clinical syndromes except for SD, which had oculomotor performance that was indistinguishable from age-matched controls. Only PSP patients displayed abnormalities in saccade velocity, whereas abnormalities in saccade gain were observed in PSP > CBS > Alzheimer's disease subjects. All patient groups except those with SD were impaired on the anti-saccade task, however only the FTLD subjects and not Alzheimer's disease, CBS or PSP groups, were able to spontaneously self-correct anti-saccade errors as well as controls. Receiver operating characteristic statistics demonstrated that oculomotor findings were superior to neuropsychological tests in differentiating PSP from other disorders, and comparable to neuropsychological tests in differentiating the other patient groups. These data suggest that oculomotor assessment may aid in the diagnosis of FTLD and related disorders
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