970 research outputs found
Theoretical and Experimental Study of Ignition Lag and Engine Knock
No full textThe author believes, on the basis of experimental ignition-lag data, that the character of a fuel cannot be stated in terms of a single constant (such as octane or cetane number) but that at least two and generally three constants are required. Thus no correlation between knock ratings can be expected if in one set of tests the charge temperature was varied while in the other the charge pressure was varied. For this reason, he favors knock rating being based on an equation characterizing the ignition lag of the fuel as a function of pressure and temperature of the charge
Regulation of gene expression by 17β-estradiol in the arcuate nucleus of the mouse through ERE-dependent and ERE-independent mechanisms
No full text17β-Estradiol (E2) modulates gene expression in the hypothalamic arcuate nucleus (ARC) to control homeostatic functions. In the ARC, estrogen receptor (ER) α is highly expressed and is an important contributor to E2's actions, controlling gene expression through estrogen response element (ERE)-dependent and -independent mechanisms. The objective of this study was to determine if known E2-regulated genes are regulated through these mechanisms. The selected genes have been shown to regulate homeostasis and have been separated into three subsections: channels, receptors, and neuropeptides. To determine if ERE-dependent or ERE-independent mechanisms regulate gene expression, two transgenic mouse models, an ERα knock-out (ERKO) and an ERα knock-in/knock-out (KIKO), which lacks a functional ERE binding domain, were used in addition to their wild-type littermates. Females of all genotypes were ovariectomized and injected with oil or estradiol benzoate (E2B). Our results suggest that E2B regulates multiple genes through these mechanisms. Of note, Cacna1g and Kcnmb1 channel expression was increased by E2B in WT females only, suggesting an ERE-dependent regulation. Furthermore, the NKB receptor, Tac3r, was suppressed by E2B in WT and KIKO females but not ERKO females, suggesting that ERα-dependent, ERE-independent signaling is necessary for Tac3r regulation. The adrenergic receptor Adra1b was suppressed by E2B in all genotypes indicating that ERα is not the primary receptor for E2B's actions. The neuropeptide Tac2 was suppressed by E2B through ERE-dependent mechanisms. These results indicate that E2B activates both ERα-dependent and independent signaling in the ARC through ERE-dependent and ERE-independent mechanisms to control gene expression.Peer reviewe
Knock-in American options
No full textA knock-in American option under a trigger clause is an option contract in which the option holder receives an American option conditional on the underlying stock price breaching a certain trigger level (also called barrier level). We present analytic valuation formulas for knock-in American options under the Black-Scholes pricing framework. The price formulas possess different analytic representations, depending on the relation between the trigger stock price level and the critical stock price of the underlying American option. We also performed numerical valuation of several knock-in American options to illustrate the efficacy of the price formulas. (C) 2004 Wiley Periodicals, Inc.Business, FinanceSSCI6ARTICLE2179-1922
Author Correction: Considerations in the search for epistasis
No full textBalvert M, Cooper-Knock J, Stamp J, et al. Author Correction: Considerations in the search for epistasis. Genome Biology . 2025;26(1): 12
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Exploring the impact of “the knock” and its aftermath on non-offending partners of sex offenders and adequacy of available support
No full textPurpose The discovery of an individual’s child sexual offending by the non-offending partner (NOP) is a watershed moment marking the beginning of a harrowing journey. This journey has been found to encompass the immediate shock, ruptured families and friendships, practical and financial struggles, and, eventually, the NOP’s attempt to rebuild their lives. The purpose of this paper was to explore the impact of the discovery on NOPs following a police home visit with an arrest/search warrant (known as “the knock”) and its aftermath. It further aimed to understand NOPs’ experience of support. Design/methodology/approach In this qualitative study, the author conducted semi-structured interviews with three NOPs who were at least two years post “knock” (and not in an active investigation) and three professionals working closely with NOPs. Thematic analysis determined key themes. Findings NOPs experience significant ongoing harm following this discovery, and support is mainly inadequate. The four key themes that emerged were discovery trauma, stigma and shame, loss and isolation, and support for indirect victims. Practical implications Recommendations include professional and public awareness in recognition of NOPs as indirect victims; national implementation of indirect victim support officers; increased provision of peer-support; trauma-informed approaches to minimise harm. Originality/value Previous research has typically overlooked the direct impacts on NOPs, particularly their support needs. This research illustrates the devastation suffered by NOPs (and their families) and highlights the need for an improved provision of support services
Information-based methods for predicting gene function from systematic gene knock-downs
No full textAbstract Background The rapid annotation of genes on a genome-wide scale is now possible for several organisms using high-throughput RNA interference assays to knock down the expression of a specific gene. To date, dozens of RNA interference phenotypes have been recorded for the nematode Caenorhabditis elegans. Although previous studies have demonstrated the merit of using knock-down phenotypes to predict gene function, it is unclear how the data can be used most effectively. An open question is how to optimally make use of phenotypic observations, possibly in combination with other functional genomics datasets, to identify genes that share a common role. Results We compared several methods for detecting gene-gene functional similarity from phenotypic knock-down profiles. We found that information-based measures, which explicitly incorporate a phenotype's genomic frequency when calculating gene-gene similarity, outperform non-information-based methods. We report the presence of newly predicted modules identified from an integrated functional network containing phenotypic congruency links derived from an information-based measure. One such module is a set of genes predicted to play a role in regulating body morphology based on their multiply-supported interactions with members of the TGF-β signaling pathway. Conclusion Information-based metrics significantly improve the comparison of phenotypic knock-down profiles, based upon their ability to enhance gene function prediction and identify novel functional modules.</p
Experimental & analytical evaluation of knock characteristics of producer gas
No full text2010 Summer.Includes bibliographic references.Covers not scanned.Print version deaccessioned 2022.Amongst the popular gaseous bio-fuels is producer gas. Evaluation of knock properties of producer gas enhances efficient utilization of this renewable energy resource in an internal combustion engine. A literature review revealed that producer gas is formed from a set of combustion-reduction reactions in a gasifier and is typically composed of 18-20% H2, 18-20%CO, 2-3% CH4, 12% CO2 and 48-50%N2. It is seen that a production process where the combustion and reduction reactions are effectively separated yields a gas rich in hydrogen. Hence based on the production method and range in gas composition five different producer gas compositions are chosen for knock evaluation. Knock evaluation for gaseous fuels has been done by previous researchers using the Methane Number method. This method requires the use of a Cooperative Fuel Research (CFR) F2 engine installed in Colorado State University’s Engines and Energy Conversion Laboratory. It was seen that the methane number of producer gas ranged from 54-131. Further it was quantitatively evaluated that addition of CO2 increases the critical compression ratio while H2 decreases it. Overall, the effect of CO2 on changing the critical compression ratio was found to be over twice that of H2. It was attempted to evaluate the methane number of producer gas using chemical kinetics software CHEMKIN. A Methane Number evaluation process was developed using CHEMKIN’s internal combustion engine model. There were significant differences between model and experiment. Recommendations for future work are discussed
Pleiotropic Effects on Tachyzoite and Host Cell Proteomes in Knock-Out Clones of the Open Reading Frames 297720 and 319730 Constitutively Expressed in T. gondii ShSp1 Tachyzoites
No full textAuthor Contributions:
Data curation, J.M., M.H., A.-C.U. and S.B.-L.; formal analysis, J.M.; funding acquisition, A.H.; investigation, K.P.A.H. and J.M.; methodology, K.P.A.H., J.M., S.B.-L. and D.A.-S.; project administration, A.H.; resources, L.-M.O.-M. and A.H.; software, M.H., A.-C.U. and S.B.-L.; validation, J.M., M.H. and A.H.; visualization, K.P.A.H. and J.M.; writing—original draft, K.P.A.H. and J.M.; writing—review and editing, K.P.A.H., J.M., M.H., A.-C.U., S.B.-L., D.A.-S., L.-M.O.-M. and A.H. All authors have read and agreed to the published version of the manuscriptToxoplasma gondii, the causative agent of toxoplasmosis widespread in animals and humans, is an intracellular apicomplexan protozoan parasite infecting a variety of host cells. Gene editing using CRISPR-Cas9 has become a standard tool to investigate the molecular genetics of this interaction. With respect to gene knock-out (KO) studies, the general paradigm implies that the gene of interest is expressed in the wildtype and that only the gene of interest is affected by the knock-out. Consequently, the observed phenotype depends on the presence or absence of genes of interest. To challenge this paradigm, we knocked out two open reading frames (ORFs) constitutively expressed in T. gondii ShSp1 tachyzoites, but not essential, namely ORF 297720 encoding a trehalose-6-phosphatase homolog and ORF 319730 encoding a You2 C2C2 zinc finger homolog. We analyzed the proteomes of tachyzoites isolated at a late stage of infection, as well as intracellular tachyzoites and host cells at an early stage of infection. The intended KO proteins were present in the T. gondii Sp1 wildtype but absent in the KO clones. Moreover, besides differentially expressed (DE) proteins specific to each KO, 17 DE proteins common to both KOs were identified in isolated tachyzoites and 39 in intracellular tachyzoites. Moreover, 76 common DE proteins were identified in host cells. Network and enrichment analyses showed that these proteins were functionally related to antiviral defense mechanisms. These results indicate that the KO of a gene of interest may not only affect the expression of other genes of the target organism, which in our case is T. gondii, but also the gene expression of its host cells. Therefore, phenotypes of KO strains may not be causally related to the KO of a given gene. Overall, this study highlights that genetic manipulation in T. gondii can lead to system-wide proteomic shifts in both parasite and host, emphasizing the need for cautious interpretation of knock-out-based functional analysesSwiss National Science FoundationDepto. de Sanidad AnimalFac. de VeterinariaTRUEpu
Interaction of pressure wave and propagating flame during knock
No full textTo determine the mechanism of interaction between a pressure wave and a propagating flame during knock, normal combustion and knock are numerically modeled in a simplified one-dimensional hydrogen-fueled spark ignition engine. The heat release rate of the flame front during knock abruptly increases when the pressure wave propagates through the reaction zone. The pressure wave in the diffusion zone perturbs temperature and thus causes thermal runaway at positions with low temperature and high reactant concentrations. Analysis of the Damkohler number (the ratio of gas dynamic time to chemical reaction time) and the estimated overpressure revealed that abruptly raised heat release rate during knock facilitates the amplification of the pressure wave and reinforces the interaction between pressure wave and chemical heat release. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Chemistry, PhysicalElectrochemistryEnergy & FuelsSCI(E)EI1ARTICLE3515510-155193
Stochastic epidemic models for emerging diseases incorporating household structure and contact tracing
No full textIn this thesis, three stochastic epidemic models for intervention for emerging diseases are considered. The models are variants of real-time, responsive intervention, based upon observing diagnosed cases and targeting intervention towards individuals they have infected or are likely to have infected, be they housemates or named contacts. These models are: (i) a local tracing model for a disease spreading amongst a community of households, wherein intervention (vaccination and/or isolation) is directed towards housemates of diagnosed individuals, (ii) a contact tracing model for a disease spreading amongst a homogeneously-mixing population, with isolation of traced contacts of a diagnosed individual, (iii) a local tracing and contact tracing model for a disease spreading amongst a community of households, with intervention directed towards housemates of both diagnosed and traced individuals. These are quantified by deriving threshold parameters that determine whether the disease will infect a few individuals or a sizeable proportion of the population, as well as probabilities for such events occurring.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
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