1,809 research outputs found

    High fidelity sorting of remarkably similar components via metal-mediated assembly.

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    Subtle differences in ligand coordination angle and rigidity lead to high fidelity sorting between individual components displaying identical coordination motifs upon metal-mediated self-assembly. Narcissistic self-sorting can be achieved between highly similar ligands that vary minimally in rigidity and internal coordination angle upon combination with Fe(ii) ions and 2-formylpyridine. Selective, sequential cage formation can be precisely controlled in a single flask from a mix of three different core ligands (and 33 total components) differing only in the hybridization of one group that is uninvolved in the metal coordination process

    Hypervelocity Star Candidates in the SEGUE G & K Dwarf Sample

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    We present 20 candidate hypervelocity stars from the Sloan Extension for Galactic Understanding and Exploration (SEGUE) G and K dwarf samples. Previous searches for hypervelocity stars have only focused on large radial velocities; in this study we also use proper motions to select the candidates. We determine the hypervelocity likelihood of each candidate by means of Monte Carlo simulations, considering the significant errors often associated with high proper motion stars. We find that nearly half of the candidates exceed their escape velocities with at least 98% probability. Every candidate also has less than a 25% chance of being a high-velocity fluke within the SEGUE sample. Based on orbits calculated using the observed six-dimensional positions and velocities, few, if any, of these candidates originate from the Galactic center. If these candidates are truly hypervelocity stars, they were not ejected by interactions with the Milky Way's supermassive black hole. This calls for a more serious examination of alternative hypervelocity-star ejection scenarios.Comment: 8 pages, 5 figures, published in ApJ, this version includes all figures as intende

    In silico identification of opossum cytokine genes suggests the complexity of the marsupial immune system rivals that of eutherian mammals

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    BACKGROUND: Cytokines are small proteins that regulate immunity in vertebrate species. Marsupial and eutherian mammals last shared a common ancestor more than 180 million years ago, so it is not surprising that attempts to isolate many key marsupial cytokines using traditional laboratory techniques have been unsuccessful. This paucity of molecular data has led some authors to suggest that the marsupial immune system is 'primitive' and not on par with the sophisticated immune system of eutherian (placental) mammals. RESULTS: The sequencing of the first marsupial genome has allowed us to identify highly divergent immune genes. We used gene prediction methods that incorporate the identification of gene location using BLAST, SYNTENY + BLAST and HMMER to identify 23 key marsupial immune genes, including IFN-γ, IL-2, IL-4, IL-6, IL-12 and IL-13, in the genome of the grey short-tailed opossum (Monodelphis domestica). Many of these genes were not predicted in the publicly available automated annotations. CONCLUSION: The power of this approach was demonstrated by the identification of orthologous cytokines between marsupials and eutherians that share only 30% identity at the amino acid level. Furthermore, the presence of key immunological genes suggests that marsupials do indeed possess a sophisticated immune system, whose function may parallel that of eutherian mammals

    Slow advancement of enteral feed volumes to prevent necrotising enterocolitis in very low birth weight infants

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    BACKGROUND: Early enteral feeding practices are potentially modifiable risk factors for necrotising enterocolitis (NEC) in very preterm or very low birth weight (VLBW) infants. Observational studies suggest that conservative feeding regimens, including slowly advancing enteral feed volumes, reduce the risk of NEC. However, slow feed advancement may delay establishment of full enteral feeding and may be associated with metabolic and infectious morbidities secondary to prolonged exposure to parenteral nutrition. OBJECTIVES: To determine effects of slow rates of enteral feed advancement on the incidence of NEC, mortality, and other morbidities in very preterm or VLBW infants. SEARCH METHODS: We used the standard Cochrane Neonatal search strategy to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 5), MEDLINE via PubMed (1966 to June 2017), Embase (1980 to June 2017), and the Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1982 to June 2017). We searched clinical trials databases, conference proceedings, previous reviews, and reference lists of retrieved articles for randomised controlled trials (RCTs) and quasi-randomised trials. SELECTION CRITERIA: Randomised or quasi-randomised controlled trials that assessed effects of slow (up to 24 mL/kg/d) versus faster rates of advancement of enteral feed volumes upon the incidence of NEC in very preterm or VLBW infants. DATA COLLECTION AND ANALYSIS: Two review authors assessed trial eligibility and risk of bias and independently extracted data. We analysed treatment effects in individual trials and reported risk ratio (RR) and risk difference (RD) for dichotomous data, and mean difference (MD) for continuous data, with respective 95% confidence intervals (CIs). We used a fixed-effect model for meta-analyses and explored potential causes of heterogeneity via sensitivity analyses. We assessed the quality of evidence at the outcome level using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. MAIN RESULTS: We identified 10 RCTs in which a total of 3753 infants participated (2804 infants participated in one large trial). Most participants were stable very preterm infants of birth weight appropriate for gestation. About one-third of all participants were extremely preterm or extremely low birth weight (ELBW), and about one-fifth were small for gestational age (SGA), growth-restricted, or compromised in utero, as indicated by absent or reversed end-diastolic flow velocity (AREDFV) in the fetal umbilical artery. Trials typically defined slow advancement as daily increments of 15 to 20 mL/kg, and faster advancement as daily increments of 30 to 40 mL/kg. Trials generally were of good methodological quality, although none was blinded.Meta-analyses did not show effects on risk of NEC (typical RR 1.07, 95% CI 0.83 to 1.39; RD 0.0, 95% CI -0.01 to 0.02) or all-cause mortality (typical RR 1.15, 95% CI 0.93 to 1.42; typical RD 0.01, 95% CI -0.01 to 0.03). Subgroup analyses of extremely preterm or ELBW infants, or of SGA or growth-restricted or growth-compromised infants, showed no evidence of an effect on risk of NEC or death. Slow feed advancement delayed establishment of full enteral nutrition by between about one and five days. Meta-analysis showed borderline increased risk of invasive infection (typical RR 1.15, 95% CI 1.00 to 1.32; typical RD 0.03, 95% CI 0.00 to 0.05). The GRADE quality of evidence for primary outcomes was "moderate", downgraded from "high" because of lack of blinding in the included trials. AUTHORS' CONCLUSIONS: Available trial data do not provide evidence that advancing enteral feed volumes at daily increments of 15 to 20 mL/kg (compared with 30 to 40 mL/kg) reduces the risk of NEC or death in very preterm or VLBW infants, extremely preterm or ELBW infants, SGA or growth-restricted infants, or infants with antenatal AREDFV. Advancing the volume of enteral feeds at a slow rate results in several days of delay in establishing full enteral feeds and may increase the risk of invasive infection

    Metabolic engineering of high-productivity CHO host lines for biomanufacturing

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    Mitochondrial function in heart failure: The impact of ischemic and non-ischemic etiology

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    Background Although cardiac mitochondrial dysfunction is associated with heart failure (HF), this is a complex syndrome with two predominant etiologies, ischemic HF (iHF) and non-ischemic HF (niHF), and the exact impact of mitochondrial dysfunction in these two distinct forms of HF is unknown. Methods and results To determine the impact of HF etiology on mitochondrial function, respiration was measured in permeabilized cardiac muscle fibers from patients with iHF (n = 17), niHF (n = 18), and healthy donor hearts (HdH). Oxidative phosphorylation capacity (OXPHOS), assessed as state 3 respiration, fell progressively from HdH to niHF, to iHF (Complex I + II: 54 ± 1; 34 ± 4; 27 ± 3 pmol·s− 1·mg− 1) as did citrate synthase activity (CSA: 206 ± 18; 129 ± 6; 82 ± 6 nmol·mg− 1·min− 1). Although still significantly lower than HdH, normalization of OXPHOS by CSA negated the difference in mass specific OXPHOS between iHF and niHF. Interestingly, Complex I state 2 respiration increased progressively from HdH, to niHF, to iHF, whether or not normalized for CSA (0.6 ± 0.2; 1.1 ± 0.3; 2.3 ± 0.3; pmol·mg− 1·CSA), such that the respiratory control ratio (RCR), fell in the same manner across groups. Finally, both the total free radical levels (60 ± 6; 46 ± 4 AU) and level of mitochondrial derived superoxide (1.0 ± 0.2; 0.7 ± 0.1 AU) were greater in iHF compared to niHF, respectively. Conclusions Thus, the HF-related attenuation in OXPHOS actually appears to be independent of etiology when the lower mitochondrial content of iHF is taken into account. However, these findings provide evidence of deleterious intrinsic mitochondrial changes in iHF, compared to niHF, including greater proton leak, attenuated OXPHOS efficiency, and augmented free radical levels

    RNA-seq: technical variability and sampling

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    <p>Abstract</p> <p>Background</p> <p>RNA-seq is revolutionizing the way we study transcriptomes. mRNA can be surveyed without prior knowledge of gene transcripts. Alternative splicing of transcript isoforms and the identification of previously unknown exons are being reported. Initial reports of differences in exon usage, and splicing between samples as well as quantitative differences among samples are beginning to surface. Biological variation has been reported to be larger than technical variation. In addition, technical variation has been reported to be in line with expectations due to random sampling. However, strategies for dealing with technical variation will differ depending on the magnitude. The size of technical variance, and the role of sampling are examined in this manuscript.</p> <p>Results</p> <p>In this study three independent Solexa/Illumina experiments containing technical replicates are analyzed. When coverage is low, large disagreements between technical replicates are apparent. Exon detection between technical replicates is highly variable when the coverage is less than 5 reads per nucleotide and estimates of gene expression are more likely to disagree when coverage is low. Although large disagreements in the estimates of expression are observed at all levels of coverage.</p> <p>Conclusions</p> <p>Technical variability is too high to ignore. Technical variability results in inconsistent detection of exons at low levels of coverage. Further, the estimate of the relative abundance of a transcript can substantially disagree, even when coverage levels are high. This may be due to the low sampling fraction and if so, it will persist as an issue needing to be addressed in experimental design even as the next wave of technology produces larger numbers of reads. We provide practical recommendations for dealing with the technical variability, without dramatic cost increases.</p

    Organizational governance to integrate sustainability projects: a case study

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    Sustainable development represents a major challenge of the 21st century. Organizations use projects to implement strategic corporate objectives, exploring sustainable development from a project management perspective is imperative. While current project management techniques are well defined in terms of content and process to manage the budget-scope-time constraint, availability of organization resources and ability to adopt project governance strategies in a changing business environment, like incorporating sustainability in business process is ambiguous, literature has not explored how to cope with a normative situation like sustainability. We consider Small-to-Mid-Size-Construction-Organizations (SMSCOs), which makes up the largest portion of the project-based industry and are most impacted by new government regulations, as our population of interest. This paper addresses two primary objectives in relation to organizational resources available for SMSCOs: to identify an organization's shortcomings in undertaking a sustainable project, and to identify means for improving organizational readiness to cope with governance of sustainable projects. A case study with a SMSCO to understand activities, resource availability, and how to improve organization readiness to undertake projects related to sustainability is discussed. A conceptual framework is presented for the adoptive project governance process to ensure resource constrained organizations like SMSCO's can align better to govern such projects. First published online: 28 Jan 201
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