6,097 research outputs found
The modelling of fuel dispersion and concentration in direct injection diesel engines
The presented investigation develops a modelling technique,
which allows measurement in a dynamically similar gas jet, to be related
to the diesel engine injection process in the presence of air swirl.
Modelling experiments have been performed for direct injection
processes from both the centre and the circumference of the combustion
chamber. A tracer gas technique has been employed, by which, concentration
of jet nozzle gas in the simulated air swirl was measured, thus
yielding information on model predicted trajectory, spread and local
fuel concentration. Gas concentration was measured using a specially
developed hot wire anemometry technique which allowed measurement in a
transient pulsed jet simulation.
The modelling theory was developed on the basis that spray droplet
velocity relative to the air entrained into the spray is small after
an initial jet disintegration, and droplet formation process. Consequently
the fuel spray is assumed to behave as an air jet bearing a mist of
liquid droplets.
Favourable comparison of model gas jet and engine fuel spray
behaviour is initially made with published film data. Further comparison
of engine performance and associated high speed photographic results,
with the model predicted fuel dispersion and local concentration levels,
is made from data obtained on a modified Petter PM test engine. The
results indicate that model predicted rich fuel regions, both at the
combustion chamber wall and within the Jet core correspond to smoke
generation areas recorded on the high speed films. Similarly, experimental
engine performance parameters such as exhaust emission levels' rate of pressure rise, and peak pressure are shown to directly relate to the
model predicted dispersion of fuel. The conclusions drawn are that the modelling technique has
potential in optimising the fuel injection equipment specification at
the design stage and effectively represents the behaviour of the modelled
engine fuel spray
Destabilization of α-helical structure in solution improves bactericidal activity of antimicrobial peptides: Opposing effects on bacterial and viral targets
We have previously examined the mechanism of antimicrobial peptides on the outer membrane of vaccinia virus. Here we show that the formulation of peptides LL37 and magainin-2B amide in polysorbate 20 (Tween-20™) results in greater reductions in virus titre than formulation without detergent, and the effect is replicated by substitution of polysorbate 20 with high ionic strength buffer. In contrast, formulation with polysorbate 20 or high ionic strength buffer has the opposite effect on bactericidal activity of both peptides, resulting in lesser reductions in titre for both gram-positive and gram-negative bacteria. Circular dichroism spectroscopy shows that the differential action of polysorbate 20 and salt on the virucidal and bactericidal activities correlates with the α-helical content of peptide secondary structure in solution, suggesting that the virucidal and bactericidal activities are mediated through distinct mechanisms. The correlation of a defined structural feature with differential activity against a host-derived viral membrane and the membranes of both gram-positive and gram-negative bacteria suggests that overall helical content in solution under physiological conditions is an important feature for consideration in the design and development of candidate peptide-based antimicrobial compounds
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The Internal Circadian Clock Increases Hunger and Appetite in the Evening Independent of Food Intake and Other Behaviors
Objective: Despite the extended overnight fast, paradoxically, people are typically not ravenous in the morning and breakfast is typically the smallest meal of the day. Here we assessed whether this paradox could be explained by an endogenous circadian influence on appetite with a morning trough, while controlling for sleep/wake and fasting/feeding effects. Design and Methods We studied 12 healthy non-obese adults (6 male; age, 20–42 year) throughout a 13-day laboratory protocol that balanced all behaviors, including eucaloric meals and sleep periods, evenly across the endogenous circadian cycle. Participants rated their appetite and food preferences by visual analog scales. Results: There was a large endogenous circadian rhythm in hunger, with the trough in the biological morning (8 AM) and peak in the biological evening (8 PM; peak-to-trough amplitude=17%; P=0.004). Similarly phased significant endogenous circadian rhythms were present in appetite for sweets, salty and starchy foods, fruits, meats/poultry, food overall, and for estimates of how much food participants could eat (amplitudes 14–25%; all P < 0.05). Conclusions: In people who sleep at night, the intrinsic circadian evening peak in appetite may promote larger meals before the fasting period necessitated by sleep. Furthermore, the circadian decline in hunger across the night would theoretically counteract the fasting-induced hunger increase that could otherwise disrupt sleep
The Worldwide Alzheimer\u27s Disease Neuroimaging Initiative: ADNI-3 updates and global perspectives
The Worldwide Alzheimer\u27s Disease Neuroimaging Initiative (WW-ADNI) is a collaborative effort to investigate imaging and biofluid markers that can inform Alzheimer\u27s disease treatment trials. It is a public-private partnership that spans North America, Argentina, Australia, Canada, China, Japan, Korea, Mexico, and Taiwan. In 2004, ADNI researchers began a naturalistic, longitudinal study that continues today around the globe. Through several successive phases (ADNI-1, ADNI-GO, ADNI-2, and ADNI-3), the study has fueled amyloid and tau phenotyping and refined neuroimaging methodologies. WW-ADNI researchers have successfully standardized analyses and openly share data without embargo, providing a rich data set for other investigators. On August 26, 2020, the Alzheimer\u27s Association convened WW-ADNI researchers who shared updates from ADNI-3 and their vision for ADNI-4
YOGY: a web-based, integrated database to retrieve protein orthologs and associated Gene Ontology terms
We present YOGY a web-based resource for orthologous proteins from nine eukaryotic organisms: Homo sapiens, Mus musculus, Rattus norvegicus, Arabidopsis thaliana, Drosophila melanogaster, Caenorhabditis elegans, Plasmodium falciparum, Schizosaccharomyces pombe and Saccharomyces cerevisiae. Using a gene name from any of these organisms as a query, this database provides comprehensive, combined information on orthologs in other species using data from five independent resources: KOGs, Inparanoid, HomoloGene, OrthoMCL and a table of curated fission and budding yeast orthologs. Associated Gene Ontology (GO) terms of orthologs can also be retrieved for functional inference. Integrating these different and complementary datasets provides a straightforward tool to identify known and predicted orthologs of proteins from a variety of species. This resource should be useful for bench scientists looking for functional clues for their genes of interest as well as for curators looking for information that can be transferred based on orthology and for rapidly identifying the relevant GO terms as an aid to literature curation. YOGY is accessible online at
A model-based cost-utility analysis of multi-professional simulation training in obstetric emergencies
ObjectiveTo determine the cost-utility of a multi-professional simulation training programme for obstetric emergencies-Practical Obstetric Multi-Professional Training (PROMPT)-with a particular focus on its impact on permanent obstetric brachial plexus injuries (OBPIs).DesignA model-based cost-utility analysis.SettingMaternity units in England.PopulationSimulated cohorts of individuals affected by permanent OBPIs.MethodsA decision tree model was developed to estimate the cost-utility of adopting annual, PROMPT training (scenario 1a) or standalone shoulder dystocia training (scenario 1b) in all maternity units in England compared to current practice, where only a proportion of English units use the training programme (scenario 2). The time horizon was 30 years and the analysis was conducted from an English National Health Service (NHS) and Personal Social Services perspective. A probabilistic sensitivity analysis was performed to account for uncertainties in the model parameters.Main outcome measuresOutcomes for the entire simulated period included the following: total costs for PROMPT or shoulder dystocia training (including costs of OBPIs), number of OBPIs averted, number of affected adult/parental/dyadic quality adjusted life years (QALYs) gained and the incremental cost per QALY gained.ResultsNationwide PROMPT or shoulder dystocia training conferred significant savings (in excess of £1 billion (1.5 million) per any type of QALY gained. The probabilistic sensitivity analysis demonstrated similar findings.ConclusionIn this model, national implementation of multi-professional simulation training for obstetric emergencies (or standalone shoulder dystocia training) in England appeared to both be cost-saving when evaluating their impact on permanent OBPIs
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