Globally Convergent Parallel Algorithm for Zeros of Polynomial Systems

Certain classes of nonlinear systems of equations, such as polynomial systems, have properties that make them particularly amenable to solution on distributed computing systems. Some algorithms, considered unfavorably on a single processor serial computer, may be excellent on a distributed system. This paper considers the solution of polynomial systems of equations via a globally convergent homotopy algorithm on a hypercube. Some computational results are reported

seamount chain subduction zone interactions implications for accretionary and erosive subduction zone behavior

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Real time monitoring of biofilm formation on coated medical devices for the reduction and interception of bacterial infections

Real time monitoring of bacterial attachment to medical devices provides opportunities to detect early biofilm formation and instigate appropriate interventions before infection develops. This study utilises long period grating (LPG) optical fibre sensors, incorporated into the lumen of endotracheal tubes (ETTs), to monitor in real time, Pseudomonas aeruginosa surface colonisation and biofilm formation. The wavelength shift of LPG attenuation bands was monitored for 24 h and compared with biofilm biomass, quantified using confocal fluorescence microscopy imaging. Biofilm formation was compared on uncoated ETTs and optical fibres, and on a biofilm resistant acrylate polymer, after challenge in an artificial sputum or minimal growth medium (RPMI-1640). The LPG sensor was able to detect a biofilm biomass as low as 81 µg/cm 2 , by comparison with the confocal image quantification. An empirical exponential function was found to the link optical attenuation wavelength shift with the inverse of the biofilm biomass, allowing quantification of biofouling from the spectral response. Quantification from the sensor allows infection interception and early device removal, to reduce, for example, the risk of ventilator associated pneumonia

Community-based perceptions of emergency care in Kenya

Access to quality emergency services is an essential component of the human right to health, but barriers to emergency care are found throughout Africa and the wider world. Data to support the development of emergency care are essential to improve access to care and further infrastructure development. We undertook this study to understand the community\u27s emergency care needs and the barriers they face when trying to access care and to engage community members with developing high impact solutions to expand access to essential emergency services. To accomplish this, we used a qualitative research methodology to conduct 59 focus groups with 528 total Kenyan community member participants. Data were coded, aggregated, and analysed using the content analysis approach. Participants were uniformly selected from all eight of the historical Kenyan provinces (Central. Coast, Eastern, Nairobi, North Eastern, Nyanza, Rift Valley, and Western), with equal rural and urban community representation. We found that socioeconomic and cultural factors play a major role both in seeking and reaching emergency care. Community members in Kenya experience a wide range of medical emergencies and seem to understand their time-critical nature. They rely on one another for assistance in the face of substantial barriers to care: a lack of a structured system, resources, transportation, trained healthcare providers, and initial care on scene. The results of this study indicate the need for specific interventions to reduce barriers to access essential emergency services in Kenya. Access to emergency care can be improved by encouraging recognition and initial treatment of emergent illness in the community, strengthening the pre­-hospital care system, improving emergency care delivery at health facilities, and creating new policies at both county and national levels

Heparin molecularly imprinted surfaces for the attenuation of complement activation in blood

Heparin-imprinted synthetic polymer surfaces with the ability to attenuate activation of both the complement and the coagulation system in whole blood were successfully produced. Imprinting was achieved using a template coated with heparin, a highly sulfated glycosaminoglycan known for its anticoagulant properties. The N,N'-diacryloylpiperazine-methacrylic acid copolymers were characterized using goniometry, AFM and XPS. The influence of the molecular imprinting process on morphology and template rebinding was demonstrated by radioligand binding assays. Surface hemocompatibility was evaluated using human whole blood without anticoagulants followed by measurement of complement activation markers C3a and sC5b-9 and platelet consumption as a surrogate coagulation activation marker. The observed low thrombogenicity of this copolymer combined with the attenuation of complement activation induced by the molecular imprint offer potential for the development of self-regulating surfaces with important potential clinical applications. We propose a mechanism for the observed phenomena based upon the recruitment of endogenous sulfated glycosaminoglycans with heparin-like activities

Finding All Isolated Solutions To Polynomial Systems Using Hompack

Although the theory of polynomial continuation has been established for over a decade (following the work of Garcia, Zangwill, and Drexler), it is difficult to solve polynomial systems using continuation in practice. Divergent paths (solutions at infinity), singular solutions, and extreme scaling of coefficients can create catastrophic numerical problems. Further, the large number of paths that typically arise can be discouraging. In this paper we summarize polynomial-solving homotopy continuation and report on the performance of three standard path-tracking algorithms (as implemented in HOMPACK) in solving three physical problems of varying degrees of difficulty. Our purpose is to provide useful information on solving polynomial systems; including specific guidelines for homotopy construction and parameter settings. The m-homogeneous strategy for constructing polynomial homotopies is outlined, along with more tradition approaches. Computational comparisons are included to illustrate and contrast the major HOMPACK options. The conclusions summarize our numerical experience and discuss areas for future research

Collapsing the Resultant Dipole System

In this paper we show how to reduce the resultant dipole system developed by Gabor, Hodgkin, and Nelson to a single quadratic equation. This system was developed to determine the resultant dipole of the heart from measurements on the body surface. Reducing the system to a quadratic equation eliminates previous difficulties in numerically solving the system

Development and characterization of a stable adhesive bond between a poly(dimethylsiloxane) catheter material and a bacterial biofilm resistant acrylate polymer coating

Catheter associated urinary tract infections (CA-UTIs) are the most common health related infections world wide, contributing significantly to patient morbidity and mortality and increased health care costs. To reduce the incidence of these infections, new materials that resist bacterial biofilm formation are needed. A composite catheter material, consisting of bulk PDMS coated with a novel bacterial biofilm resistant polyacrylate (EGDPEA–co-DEGMA) has been proposed. The coated material shows excellent bacterial resistance when compared to commercial catheter materials but delamination of the coatings under mechanical stress presents a challenge. In this work, the use of oxygen plasma treatment to improve the wettability and reactivity of the PDMS catheter material and improve adhesion with the EGDPEA–co-DEGMA coating has been investigated. Argon Cluster 3D-imaging Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) has been used to probe the buried adhesive interface between the EGDPEA–co-DEGMA coating and the treated PDMS. ToF-SIMS analysis was performed in both dry and frozen-hydrated states and results were compared to mechanical tests. From the ToF-SIMS data we have been able to observe the presence of PDMS, silicates, salt particles, cracks and water at the adhesive interface. In the dry catheters, low molecular weight PDMS oligomers at the interface were associated with poor adhesion. When hydrated, the hydrophilic silicates attracted water to the interface and led to easy delamination of the coating. The best adhesion results, under hydrated conditions, were obtained using a combination of 5 min O2 plasma treatment and silane primers. Cryo-ToF-SIMS analysis of the hydrated catheter material showed that the bond between the primed PDMS catheter and the EGDPEA–co-DEGMA coating was stable in the presence of water. The resulting catheter material was resisted Escherichia coli and Proteus mirabilis biofilm colonization by up to 95 % compared with uncoated PDMS after 10 days of continuous bacterial exposure and had the mechanical properties necessary for use as a urinary catheter

An improved Greengenes taxonomy with explicit ranks for ecological and evolutionary analyses of bacteria and archaea

Reference phylogenies are crucial for providing a taxonomic framework for interpretation of marker gene and metagenomic surveys, which continue to reveal novel species at a remarkable rate. Greengenes is a dedicated full-length 16S rRNA gene database that provides users with a curated taxonomy based on de novo tree inference. We developed a ‘taxonomy to tree' approach for transferring group names from an existing taxonomy to a tree topology, and used it to apply the Greengenes, National Center for Biotechnology Information (NCBI) and cyanoDB (Cyanobacteria only) taxonomies to a de novo tree comprising 408 315 sequences. We also incorporated explicit rank information provided by the NCBI taxonomy to group names (by prefixing rank designations) for better user orientation and classification consistency. The resulting merged taxonomy improved the classification of 75% of the sequences by one or more ranks relative to the original NCBI taxonomy with the most pronounced improvements occurring in under-classified environmental sequences. We also assessed candidate phyla (divisions) currently defined by NCBI and present recommendations for consolidation of 34 redundantly named groups. All intermediate results from the pipeline, which includes tree inference, jackknifing and transfer of a donor taxonomy to a recipient tree (tax2tree) are available for download. The improved Greengenes taxonomy should provide important infrastructure for a wide range of megasequencing projects studying ecosystems on scales ranging from our own bodies (the Human Microbiome Project) to the entire planet (the Earth Microbiome Project). The implementation of the software can be obtained from http://sourceforge.net/projects/tax2tree/