4,647 research outputs found

    Characterisation of Spray Development from Spark-Eroded and Laser-Drilled Multihole Injectors in an Optical DISI Engine and in a Quiescent Injection Chamber

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    This paper addresses the need for fundamental understanding of the mechanisms of fuel spray formation and mixture preparation in direct injection spark ignition (DISI) engines. Fuel injection systems for DISI engines undergo rapid developments in their design and performance, therefore, their spray breakup mechanisms in the physical conditions encountered in DISI engines over a range of operating conditions and injection strategies require continuous attention. In this context, there are sparse data in the literature on spray formation differences between conventionally drilled injectors by spark erosion and latest Laser-drilled injector nozzles. A comparison was first carried out between the holes of spark-eroded and Laser-drilled injectors of same nominal type by analysing their in-nozzle geometry and surface roughness under an electron microscope. Then the differences in their spray characteristics under quiescent conditions, as well as in a motoring optical engine, are discussed on the basis of high-speed imaging experiments and image processing methods. Specifically, the spray development mechanism was quantified by spray tip penetration and cone angle data under a range of representative low-load and high-low engine operating conditions (0.5 bar and 1.0 bar absolute, respectively), as well as at low and high injector body temperatures (20 °C and 90 °C) to represent cold and warm engine-head conditions. Droplet sizing was also performed with the two injectors using Phase Doppler Anemometry in a quiescent chamber

    Seasonal changes in phytoplankton biomass on the Western Agulhas bank, South Africa

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    Data on temporal and spatial changes in phytoplankton biomass and distribution on the western Agulhas Bank during the main spawning season of pelagic fish were obtained from monthly cruises conducted betweenAugust and March in 1993/94 and September and March in 1994/95. The period was divided into three oceanographic seasons based on different levels of upwelling activity: late winter (August and September), spring(October–December) and summer (January–March). Cross-shelf and vertical distribution patterns of chlorophyll changed markedly during these seasonal periods, reflecting changes in hydrographic structure and in nutrient availability. During late winter, chlorophyll was evenly distributed in the deep, upper-mixed layer (>40 m) across the shelf. A clump-forming Thalassiosira sp. contributed to the moderately high mean chlorophyllconcentration (1.9 mg·m–3) in the upper 30 m. In October and/or September, warming of surface waters inshore gave rise to a modest (2–5 mg chl·m–3) spring bloom, typical of the temperate zone. This was terminated in November by an influx across the shelf of warm, nutrient-impoverished water. Upwelling was sporadic and weak in spring. Summer was characterized by intense, episodic upwelling inshore, with pronounced cross-shelf thermal gradients, intensified by the presence of water of Agulhas origin along the shelf-edge. During an upwelling cycle, rapid hydrographic and biological changes occur over four phases: onset of upwelling, sustained upwelling, quiescence and downwelling. The upwelling productive zone, bounded by the 20°C isotherm, varied fro

    Similar Inflammatory Responses following Sprint Interval Training Performed in Hypoxia and Normoxia

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    Sprint interval training (SIT) is an efficient intervention capable of improving aerobic capacity and exercise performance. This experiment aimed to determine differences in training adaptations and the inflammatory responses following 2 weeks of SIT (30 s maximal work, 4 min recovery; 4–7 repetitions) performed in normoxia or hypoxia. Forty-two untrained participants [(mean ± SD), age 21 ±1 years, body mass 72.1 ±11.4 kg, and height 173 ±10 cm] were equally and randomly assigned to one of three groups; control (CONT; no training, n = 14), normoxic (NORM; SIT in FiO2: 0.21, n = 14), and normobaric hypoxic (HYP; SIT in FiO2: 0.15, n = 14). Participants completed a V ˙ O 2peak V˙O2peak test, a time to exhaustion (TTE) trial (power = 80% V ˙ O 2peak V˙O2peak) and had hematological [hemoglobin (Hb), haematocrit (Hct)] and inflammatory markers [interleukin-6 (IL-6), tumor necrosis factor-α (TNFα)] measured in a resting state, pre and post SIT. V ˙ O 2peak V˙O2peak (mL.kg−1.min−1) improved in HYP (+11.9%) and NORM (+9.8%), but not CON (+0.9%). Similarly TTE improved in HYP (+32.2%) and NORM (+33.0%), but not CON (+3.4%) whilst the power at the anaerobic threshold (AT; W.kg−1) also improved in HYP (+13.3%) and NORM (+8.0%), but not CON (–0.3%). AT (mL.kg−1.min−1) improved in HYP (+9.5%), but not NORM (+5%) or CON (–0.3%). No between group change occurred in 30 s sprint performance or Hb and Hct. IL-6 increased in HYP (+17.4%) and NORM (+20.1%), but not CON (+1.2%), respectively. TNF-α increased in HYP (+10.8%) NORM (+12.9%) and CON (+3.4%). SIT in HYP and NORM increased V ˙ O 2peak V˙O2peak, power at AT and TTE performance in untrained individuals, improvements in AT occurred only when SIT was performed in HYP. Increases in IL-6 and TNFα reflect a training induced inflammatory response to SIT; hypoxic conditions do not exacerbate this

    Identification and classification of vertical chlorophyll patterns in the Benguela upwelling system and Angola-Benguela front using an artificial neural network

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    Information on the vertical chlorophyll structure in the ocean is important for estimating integrated chlorophyll a and primary production from satellite. For this study, vertical chlorophyll profiles from the Benguela upwelling system and the Angola-Benguela front were collected in winter to identify characteristic profiles. A shifted Gaussian model was fitted to each profile to estimate four parameters that defined the shape of the curve: the background chlorophyll concentration (B0), the height parameter of the peak (h), the width of the peak (&#963) and the depth of the chlorophyll peak (zm). A type of artificial neural network called a self-organizing map (SOM) was then used on these four parameters to identify characteristic profiles. The analysis identified a continuum of chlorophyll patterns, from those with large surface peaks (>10 mg m-3) to those with smaller near-surface peaks

    Assessment of the food available to cape anchovy during their spawning season

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    The Cape anchovy Engraulis capensis spawns serially between September and February each year on the western Agulhas Bank, South Africa. Food availability in terms of copepod biomass is important for successfulspawning and subsequent recruitment. This note investigates the variability within a spawning season (1993/94 and 1994/95) of copepod biomass on the western Bank and demonstrates that the food available to the Capeanchovy cannot be adequately assessed by a single mid-season estimate, as was the previous sampling strategy. The mid-season estimate of food availability failed to reveal important fluctuations, such as the small biomass of copepods in January 1994, which contributed to the early cessation of spawning and subsequent poor recruitment in 1994. A strategy, based on monthly sampling, is recommended for future sampling programmes

    The re-emergence of natural products for drug discovery in the genomics era

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    Natural products have been a rich source of compounds for drug discovery. However, their use has diminished in the past two decades, in part because of technical barriers to screening natural products in high-throughput assays against molecular targets. Here, we review strategies for natural product screening that harness the recent technical advances that have reduced these barriers. We also assess the use of genomic and metabolomic approaches to augment traditional methods of studying natural products, and highlight recent examples of natural products in antimicrobial drug discovery and as inhibitors of protein-protein interactions. The growing appreciation of functional assays and phenotypic screens may further contribute to a revival of interest in natural products for drug discovery

    Expression of the enteroviral capsid protein VP1 in the islet cells of patients with type 1 diabetes is associated with induction of protein kinase R and downregulation of Mcl-1

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    The final publication is available at link.springer.com/article/10.1007%2Fs00125-012-2745-4Immunohistochemical staining reveals that the enteroviral capsid protein VP1 is present at higher frequency in the insulin-containing islets of patients with recent-onset type 1 diabetes than in controls. This is consistent with epidemiological evidence suggesting that enteroviral infection may contribute to the autoimmune response in type 1 diabetes. However, immunostaining of VP1 is not definitive since the antibody widely used to detect the protein (Clone 5D8/1) might also cross-react with additional proteins under some conditions. Therefore, we sought to verify that VP1 immunopositivity correlates with additional markers of viral infection

    Pancreatectomy is underused in NSW regions with low institutional surgical volumes: A population data linkage study

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    © 2017 AMPCo Pty Ltd. Produced with Elsevier B.V. All rights reserved. Objective: To examine differences in the proportions of people diagnosed with pancreatic cancer who underwent pancreatectomy, post-operative outcomes and 5-year survival in different New South Wales administrative health regions of residence. Design, setting and participants: Retrospective analysis of NSW data on pancreatic cancer incidence and surgery, 2005e2013. Main outcome measures: The proportion of newly diagnosed patients with pancreatic cancer who were resected in each region; 90-day post-operative mortality; one-year post-operative survival; 5-year post-diagnosis survival. Results: 14% of people diagnosed with pancreatic cancer during 2010e2013 (431 of 3064) underwent pancreatectomy, an average of 108 resections per year. After adjusting for age, sex and comorbidities, the proportion that underwent resection varied significantly between regions, ranging between 8% and 21% (P<0.001). Higher resection rates were not associated with higher post-operative 90-day mortality or lower one-year survival (unadjusted and risk-adjusted analyses). Higher resection rates were associated with higher 5-year post-diagnosis survival: the mean survival in regions with resection rates below 10% was 3.4%, compared with 7.2% in regions with rates greater than 15% (unadjusted and adjusted survival analyses; P<0.001). There was a positive association between regional resection rate and the pancreatectomy volume of hospitals during 2005e2009. An additional 32 people would be resected annually if resection rates in low rate regions were increased to the 80th percentile regional resection rate (18%). Conclusion: There is significant geographic variation in the proportion of people with pancreatic cancer undergoing pancreatectomy, and the 5-year survival rate is higher in regions where this proportion is higher
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