1,111 research outputs found

    Genomic Microarray Quality Assurance

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    Systems level analysis of two-component signal transduction systems in Erwinia amylovora: Role in virulence, regulation of amylovoran biosynthesis and swarming motility

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    <p>Abstract</p> <p>Background</p> <p>Two-component signal transduction systems (TCSTs), consisting of a histidine kinase (HK) and a response regulator (RR), represent a major paradigm for signal transduction in prokaryotes. TCSTs play critical roles in sensing and responding to environmental conditions, and in bacterial pathogenesis. Most TCSTs in <it>Erwinia amylovora </it>have either not been identified or have not yet been studied.</p> <p>Results</p> <p>We used a systems approach to identify TCST and related signal transduction genes in the genome of <it>E. amylovora</it>. Comparative genomic analysis of TCSTs indicated that <it>E. amylovora </it>TCSTs were closely related to those of <it>Erwinia tasmaniensis</it>, a saprophytic enterobacterium isolated from apple flowers, and to other enterobacteria. Forty-six TCST genes in <it>E. amylovora </it>including 17 sensor kinases, three hybrid kinases, 20 DNA- or ligand-binding RRs, four RRs with enzymatic output domain (EAL-GGDEF proteins), and two kinases were characterized in this study. A systematic TCST gene-knockout experiment was conducted, generating a total of 59 single-, double-, and triple-mutants. Virulence assays revealed that five of these mutants were non-pathogenic on immature pear fruits. Results from phenotypic characterization and gene expression experiments indicated that several groups of TCST systems in <it>E. amylovora </it>control amylovoran biosynthesis, one of two major virulence factors in <it>E. amylovora</it>. Both negative and positive regulators of amylovoran biosynthesis were identified, indicating a complex network may control this important feature of pathogenesis. Positive (non-motile, EnvZ/OmpR), negative (hypermotile, GrrS/GrrA), and intermediate regulators for swarming motility in <it>E. amylovora </it>were also identified.</p> <p>Conclusion</p> <p>Our results demonstrated that TCSTs in <it>E. amylovora </it>played major roles in virulence on immature pear fruit and in regulating amylovoran biosynthesis and swarming motility. This suggested presence of regulatory networks governing expression of critical virulence genes in <it>E. amylovora</it>.</p

    Addressing decision making for remanufacturing operations and design-for-remanufacture

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    Remanufacturing is a process of returning a used product to at least original equipment manufacturer original performance specification from the customers' perspective and giving the resultant product a warranty that is at least equal to that of a newly manufactured equivalent. This paper explains the need to combine ecological concerns and economic growth and the significance of remanufacturing in this. Using the experience of an international aero-engine manufacturer it discusses the impact of the need for sustainable manufacturing on organisational business models. It explains some key decision-making issues that hinder remanufacturing and suggests effective solutions. It presents a peer-validated, high-level design guideline to assist decision-making in design in order to support remanufacturing. The design guide was developed in the UK through the analysis of selections of products during case studies and workshops involving remanufacturing and conventional manufacturing practitioners as well as academics. It is one of the initial stages in the development of a robust design for remanufacture guideline

    Classical integrability and quantum aspects of the AdS(3) x S(3) x S(3) x S(1) superstring

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    In this paper we continue the investigation of aspects of integrability of the type IIA AdS(3) x S(3) x S(3) x S(1) and AdS(3) x S(3) x T(4) superstrings. By constructing a one parameter family of flat connections we prove that the Green-Schwarz string is classically integrable, at least to quadratic order in fermions, without fixing the kappa-symmetry. We then compare the quantum dispersion relation, fixed by integrability up to an unknown interpolating function h(lambda), to explicit one-loop calculations on the string worldsheet. For AdS(3) x S(3) x S(3) x S(1) the spectrum contains heavy, as well as light and massless modes, and we find that the one-loop contribution differs depending on how we treat these modes showing that similar regularization ambiguities as appeared in AdS(4)/CFT(3) occur also here.Comment: 29 pages; v2: updated references and acknowledgmen

    Depression, anxiety, and psychological distress among caregivers of young children in rural Lesotho: Associations with food insecurity, household death and parenting stress

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    Good mental health is a critical resource for mothers and caregivers of young children, given the central role of mental health in enabling responsive caregiving. However, fulfilling caregiving responsibilities under challenging circumstances such as extreme poverty, food insecurity, and gender inequality intensifies vulnerability to poor mental health. Previous research focuses on mental health of mothers, while in many LMICs children are cared for by other caregivers, such as grandparents. We examined the prevalence of mental health problems among primary caregivers of young children in rural Lesotho, and investigated factors associated with these mental health problems. We analysed baseline data from a cluster randomised controlled trial, where all caregivers with children between 1 and 5 years old across 34 villages were invited to participate. The analysis included mental health data from 781 caregivers of 998 children. We assessed caregiver mental health using three self-report screening instruments. Univariate and multivariate regression modelling tested associations between caregiver, child and household variables and (1) depression symptoms (PHQ-9), (2) anxiety symptoms (GAD-7), (3) psychological distress (SRQ-20), (4) suicidal ideation and (5) help-seeking for mental health. This study reported a high prevalence of symptoms of psychological distress (46.2%), depression (25.7%), anxiety (17.1%) and suicidal ideation (27.5%) among caregivers. Greater prevalence was associated with food insecurity, parenting stress or recent death in the family/household. Older caregivers reported higher rates of psychological distress and depression, while younger caregivers reported higher rates of anxiety. Suicidal ideation was associated with greater food insecurity and parenting stress, and lower caregiver education. Our findings support the need to address intersecting public health issues to improve conditions for caregivers in these settings. Targeting modifiable risk factors such as food insecurity among individuals within a society who carry disproportionate burdens of caregiving should be prioritised, especially in contexts of scarcity, where mental health is not prioritised

    Light-cone gauge Hamiltonian for AdS_4 x CP^3 superstring

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    It is developed the phase-space formulation for the Type IIA superstring on the AdS_4 x CP^3 background in the kappa-symmetry light-cone gauge for which the light-like directions are taken from the D=3 Minkowski boundary of AdS_4. After fixing bosonic light-cone gauge the superstring Hamiltonian is expressed as a function of the transverse physical variables and in the quadratic approximation corresponds to the light-cone gauge-fixed IIA superstring in flat space.Comment: 12 pages, LaTeX; v2 minor improvements of the text, misprints corrected, reference added; v3: missing terms in Eqs.(8),(53) and (56) adde
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