1,327 research outputs found

    Analysis of performance characteristics in ground effect of a large scale V/STOL multi-fan-in-wing transport model

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    Performance characteristics from static tests in ground effect of V/STOL transport mode

    A stochastic model of oncogene expression and the relevance of this model to cancer therapy

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    BACKGROUND: Ablation of an oncogene or of the activity of the protein it encodes can result in apoptosis and/or inhibit tumor cell proliferation. Therefore, if the oncogene or set of oncogenes contributing maximally to a tumor cell's survival can be identified, such oncogene(s) are the most appropriate target(s) for maximizing tumor cell kill. METHODS AND RESULTS: A mathematical model is presented that describes cellular phenotypic entropy as a function of cellular proliferation and/or survival, and states of transformation and differentiation. Oncogenes become part of the cellular machinery, block apoptosis and differentiation or promote proliferation and give rise to new states of cellular transformation. Our model gives a quantitative assessment of the amount of cellular death or growth inhibition that result from the ablation of an oncogene's protein product. We review data from studies of chronic myelogenous leukemia and K562 cells to illustrate these principles. CONCLUSION: The model discussed in this paper has implications for oncogene-directed therapies and their use in combination with other therapeutic modalities

    Finite-Element Analysis of Shear-off Failure of Keyed Dry Joints in Precast Concrete Segmental Bridges

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    This article has been made available through the Brunel Open Access Publishing Fund.The structural behaviour of precast concrete segmental bridges is largely dependent on the behaviour of the joints between segments. The current practice is to use small keys that are usually unreinforced, distributed over the height of the web and the flange of concrete segments and these keys are normally dry. In this study, a numerical analysis model was established based on ABAQUS finite element code to investigate structural behaviour of keyed dry joints under direct shear. The concrete damage plasticity model along with the pseudo-damping scheme were incorporated to analyse the system for microcracks and to stabilize the solution, respectively. The numerical model is calibrated by full-scale experimental results published elsewhere. It was found that the predicted ultimate load, cracking evolution history, and final crack pattern agree reasonably well with experiment results. The validated numerical model was then employed for parametric study on factors affecting shear behaviour of keyed dry joints, in this case confining pressure. It has been found that shear capacity predicted by AASHTO diverges from that predicted by numerical analysis at high confining pressure because the contribution of friction in the total shear capacity reduces with the increase in confining pressure. Hence, it is recommended to reduce the friction coefficient used in AASHTO code when high confining pressure is applied. Moreover, the propagation of inclined crack is arrested at high confining pressure due to the fact that the fracture propagation direction is governed by the criterion of the maximum energy release rate

    Employer Escape Hatch Closed in Georgia: How the Interpretation of Georgia\u27s Apportionment Statute in Zaldivar Prohibits Employers from Using Respondeat Superior to Eschew Direct Negligence Claims

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    In Zaldivar v. Prickett, Prickett (plaintiff)was working on behalf of his employer (Overhead Door) when he collided with Zaldivar (defendant). Zaldivar filed a Notice of Fault of Nonparty under Georgia\u27s apportionment statute; this had to effect of requiring a jury to consider the fault of Overhead Door, which had recently received three anonymous phone calls complaining about Prickett\u27s driving. The Georgia Supreme Court held that Georgia\u27s Apportionment statute required that fault be assigned to Overhead Door, despite Prickett\u27s inability to recover from Overhead Door. In this Note, I vary the facts of Zaldivar: Zaldivar becomes Klutzy Kellie; Prickett becomes Prudent Peter; Overhead Door becomes Dan\u27s Doors; and I add the fact that Klutzy Kellie was working on behalf of her employer, Tom\u27s Transportation, when the accident occurred. I assume that Klutzy Kellie recently received DUIs, that Prudent Peter sued Tom\u27s Transportation for negligent entrustment (but did not allege punitive damages), and that Tom\u27s Transportation admitted respondeat superior. Under Georgia\u27s old case law, Tom\u27s Transportation would be entitled to summary judgment on the negligent entrustment claim against it since it admitted respondeat superior and since no punitive damages were asserted. Dan\u27s Doors, however, would not have the opportunity to avoid fault being apportioned to it because the Notice of Fault of Nonparty is not a negligent entrustment claim. I argue that Zaldivar overturns the latter inequitable result by removing employers\u27 entitlement to summary judgment on direct negligence claims against them when they admit respondeat superior

    Production of Succinic Acid From Basfia succiniciproducens

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    Basfia succiniciproducens is a facultative anaerobic capnophilic bacterium, isolated from rumen, that naturally produces high amounts of succinic acid by fixing CO2 and using fumarate as final electron acceptor. This metabolic feature makes it one of the ideal candidates for developing biotechnological industrial routes that could eventually replace the polluting and environment unfriendly petrochemical ones that are still main sources for the production of this value-added compound. In fact, due to the large number of applications of succinic acid that range from the more traditional ones as food additive or pharmaceutical intermediate to the most recent as building block for biopolymers and bioplastic, increasing demand and market size growth are expected in the next years. In line with a “green revolution” needed to preserve our environment, the great challenge is the establishment of commercially viable production processes that exploit renewable materials and in particular preferably non-food lignocellulosic biomasses and waste products. In this review, we describe the currently available literature concerning B. succiniciproducens since the strain was first isolated, focusing on the different renewable materials and fermentation strategies used to improve succinic acid production titers to date. Moreover, an insight into the metabolic engineering approaches and the key physiological characteristics of B. succiniciproducens deduced from the different studies are presented

    Action Boundary Proximity Effects on Perceptual-Motor Judgments

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    INTRODUCTION: Designed as a more ecological measure of reaction times, the Perception-Action Coupling Task (PACT) has shown good reliability and within-subject stability. However, a lengthy testing period was required. Perceptual-motor judgments are known to be affected by proximity of the stimulus to the action boundary. The current study sought to determine the effects of action boundary proximity on PACT performance, and whether redundant levels of stimuli, eliciting similar responses, can be eliminated to shorten the PACT.METHODS: There were 9 men and 7 women who completed 4 testing sessions, consisting of 3 familiarization cycles and 6 testing cycles of the PACT. For the PACT, subjects made judgments on whether a series of balls presented on a tablet afford "posting" (can fit) through a series of apertures. There were 8 ratios of ball to aperture size (B-AR) presented, ranging from 0.2 to 1.8, with each ratio appearing 12 times (12 trials) per cycle. Reaction times and judgment accuracy were calculated, and averaged across all B-ARs. Ratios and individual trials within each B-AR were systematically eliminated. Variables were re-averaged, and intraclass correlation coefficients (ICC) and coefficients of variation (CVTE) were calculated in an iterative manner.RESULTS: With elimination of the 0.2 and 1.8 B-ARs, the PACT showed good reliability (ICC = 0.81-0.99) and consistent within-subject stability (CVTE = 2.2-14.7%). Reliability (ICC = 0.81-0.97) and stability (CVTE = 2.6-15.6%) were unaffected with elimination of up to 8 trials from each B-AR.DISCUSSION: The shortened PACT resulted in an almost 50% reduction in total familiarization/testing time required, significantly increasing usability.Johnson CD, LaGoy AD, Pepping G-J, Eagle SR, Beethe AZ, Bower JL, Alfano CA, Simpson RJ, Connaboy C. Action boundary proximity effects on perceptual-motor judgments. Aerosp Med Hum Perform. 2019; 90(12):1000-1008

    An optimized strategy to measure protein stability highlights differences between cold and hot unfolded states

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    Macromolecular crowding ought to stabilize folded forms of proteins, through an excluded volume effect. This explanation has been questioned and observed effects attributed to weak interactions with other cell components. Here we show conclusively that protein stability is affected by volume exclusion and that the effect is more pronounced when the crowder's size is closer to that of the protein under study. Accurate evaluation of the volume exclusion effect is made possible by the choice of yeast frataxin, a protein that undergoes cold denaturation above zero degrees, because the unfolded form at low temperature is more expanded than the corresponding one at high temperature. To achieve optimum sensitivity to changes in stability we introduce an empirical parameter derived from the stability curve. The large effect of PEG 20 on cold denaturation can be explained by a change in water activity, according to Privalov's interpretation of cold denaturation

    Influence of the state of light on the optically induced interparticle interaction

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    A general expression for the energy of interparticle interaction induced by an arbitrary mode of light is determined using quantum electrodynamics, and it is shown that the Casimir-Polder potential is included within this quantum result. Equations are also derived for the corresponding coupling induced by multimode number states of light, and the dependence of the pair energy on the Poynting vector and polarization state is determined. Attention is then focused on the interactions between particles trapped in counterpropagating coherent beams, both with and without interference, and it is shown that the results afford insights into the multiparticle structures that can be optically fabricated with counterpropagating input. Brief consideration is also given to the effect of squeezing the optical coherent state. Extending previous studies of optical binding in Laguerre-Gaussian beams, results are given for the case of particles trapped at radially different locations within the beam structure. Finally, consideration is given to interparticle interactions induced by broadband light, and it is shown how the length of optically fabricated particle chains can be controlled by the use of wavelength filters

    Intersession Reliability and Within-Session Stability of a Novel Perception-Action Coupling Task

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    BACKGROUND: The perception-action coupling task (PACT) was designed as a more ecologically valid measure of alertness/reaction times compared to currently used measures by aerospace researchers. The purpose of this study was to assess the reliability, within-subject variability, and systematic bias associated with the PACT. METHODS: There were 16 subjects (men/women = 9/7; age = 27.8 +/- 3.6 yr) who completed 4 identical testing sessions. The PACT requires subjects to make judgements on whether a virtual ball could fit into an aperture. For each session, subjects completed nine cycles of the PACT, with each cycle lasting 5 min. Judgement accuracy and reaction time parameters were calculated for each cycle. Systematic bias was assessed with repeated-measures ANOVA, reliability with intraclass correlation coefficients (ICC), and within-subject variability with coefficients of variation (CVTE). RESULTS: Initiation time (Mean = 0.1065 s) showed the largest systematic bias, requiring the elimination of three cycles to reduce bias, with all other variables requiring, at the most, one. All variables showed acceptable reliability (ICC > 0.70) and within-subject variability (CVTE <20%) with only one cycle after elimination of the first three cycles. CONCLUSIONS: With a three-cycle familiarization period, the PACT was found to be reliable and stable
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