2,702 research outputs found

    Parity restoration in the Highly Truncated Diagonalization Approach: application to the outer fission barrier of 240^{240}Pu

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    The restoration of the parity symmetry has been performed in the framework of the Highly Truncated Diagonalization Approach suited to treat correlations in an explicitly particle-number conserving microscopic approach. To do so we have assumed axial symmetry and used a generalized Wick's theorem due to L\"owdin in a projection-after-variation scheme. We have chosen the Skyrme SkM∗^* energy-density functional for the particle-hole channel and a density-independent delta force for the residual interaction. We have applied this approach in the region of the outer fission barrier of the 240^{240}Pu nucleus. As a result, we have shown that the Kπ=0+K^{\pi} = 0^+ fission isomeric state is statically unstable against intrinsic-parity breaking modes, while the projection does not affect the energy at the top of the intrinsic outer fission barrier. Altogether, this leads to an increase of the height of the outer fission barrier--with respect to the fission isomeric state--by about 350 keV, affecting thus significantly the fission-decay lifetime of the considered fission isomer

    Simple Combined Model for Nonlinear Excitations in DNA

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    We propose a new simple model for DNA denaturation bases on the pendulum model of Englander\cite{A1} and the microscopic model of Peyrard {\it et al.},\cite{A3} so called "combined model". The main parameters of our model are: the coupling constant kk along each strand, the mean stretching y∗y^\ast of the hydrogen bonds, the ratio of the damping constant and driven force γ/F\gamma/F. We show that both the length LL of unpaired bases and the velocity vv of kinks depend on not only the coupling constant kk but also the temperature TT. Our results are in good agreement with previous works.Comment: 6 pages, 10 figures, submitted to Phys. Rev.

    Investigation of Anti-Phase Asymmetric Quiet Rotor Technology

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    The future of urban air mobility has a well-known tall pole challenge in the form of community acceptance which largely comes from the noise. This paper presents a proposed anti-phase rotor technology that could reduce noise sources such as blade vortex interaction noise. The anti-phase rotor technology includes a rotor design with various anti-phase alternating trailing edge patterns and a rotor design with an asymmetric blade tip. Four small-scale anti-phase rotors are fabricated by 3D printing for acoustic measurements conducted in a low-speed open-circuit wind tunnel to assess the effectiveness of the proposed anti-phase rotor technology. Preliminary test results appear to be promising and indicate that the anti-phase rotor designs could be a practical means of reducing blade vortex interactions and noise. The four tested anti-phase rotor designs have peak acoustic performance depending on the RPM and thrust which suggests improved performance through design optimization could be achieved for specific mission requirements

    Real-Time Adaptive Least-Squares Drag Minimization for Performance Adaptive Aeroelastic Wing

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    This paper contains a simulation study of a real-time adaptive least-squares drag minimization algorithm for an aeroelastic model of a flexible wing aircraft. The aircraft model is based on the NASA Generic Transport Model (GTM). The wing structures incorporate a novel aerodynamic control surface known as the Variable Camber Continuous Trailing Edge Flap (VCCTEF). The drag minimization algorithm uses the Newton-Raphson method to find the optimal VCCTEF deflections for minimum drag in the context of an altitude-hold flight control mode at cruise conditions. The aerodynamic coefficient parameters used in this optimization method are identified in real-time using Recursive Least Squares (RLS). The results demonstrate the potential of the VCCTEF to improve aerodynamic efficiency for drag minimization for transport aircraft

    Evaluation of pre-analytical factors affecting plasma DNA analysis.

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    Pre-analytical factors can significantly affect circulating cell-free DNA (cfDNA) analysis. However, there are few robust methods to rapidly assess sample quality and the impact of pre-analytical processing. To address this gap and to evaluate effects of DNA extraction methods and blood collection tubes on cfDNA yield and fragment size, we developed a multiplexed droplet digital PCR (ddPCR) assay with 5 short and 4 long amplicons targeting single copy genomic loci. Using this assay, we compared 7 cfDNA extraction kits and found cfDNA yield and fragment size vary significantly. We also compared 3 blood collection protocols using plasma samples from 23 healthy volunteers (EDTA tubes processed within 1 hour and Cell-free DNA Blood Collection Tubes processed within 24 and 72 hours) and found no significant differences in cfDNA yield, fragment size and background noise between these protocols. In 219 clinical samples, cfDNA fragments were shorter in plasma samples processed immediately after venipuncture compared to archived samples, suggesting contribution of background DNA by lysed peripheral blood cells. In summary, we have described a multiplexed ddPCR assay to assess quality of cfDNA samples prior to downstream molecular analyses and we have evaluated potential sources of pre-analytical variation in cfDNA studies

    Fabrication and Qualification of Coated Chip-on-Board Technology for Miniaturized Space Systems

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    The results of a study carried out in order to manufacture and verify the quality of chip-on-board (COB) packaging technology are presented. The COB, designed for space applications, was tested under environmental stresses, temperature cycling, and temperature-humidity-bias. Both robustness in space applications and in environmental protection on the ground-complete reliability without hermeticity were searched for. The epoxy-parylene combinations proved to be superior to other materials tested

    Knowledge-Informed Machine Learning for Cancer Diagnosis and Prognosis: A review

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    Cancer remains one of the most challenging diseases to treat in the medical field. Machine learning has enabled in-depth analysis of rich multi-omics profiles and medical imaging for cancer diagnosis and prognosis. Despite these advancements, machine learning models face challenges stemming from limited labeled sample sizes, the intricate interplay of high-dimensionality data types, the inherent heterogeneity observed among patients and within tumors, and concerns about interpretability and consistency with existing biomedical knowledge. One approach to surmount these challenges is to integrate biomedical knowledge into data-driven models, which has proven potential to improve the accuracy, robustness, and interpretability of model results. Here, we review the state-of-the-art machine learning studies that adopted the fusion of biomedical knowledge and data, termed knowledge-informed machine learning, for cancer diagnosis and prognosis. Emphasizing the properties inherent in four primary data types including clinical, imaging, molecular, and treatment data, we highlight modeling considerations relevant to these contexts. We provide an overview of diverse forms of knowledge representation and current strategies of knowledge integration into machine learning pipelines with concrete examples. We conclude the review article by discussing future directions to advance cancer research through knowledge-informed machine learning.Comment: 41 pages, 4 figures, 2 table

    Salmonella Pathogenesis and Processing of Secreted Effectors by Caspase-3

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    The enteric pathogen Salmonella enterica serovar Typhimurium causes food poisoning resulting in gastroenteritis. The S. Typhimurium effector Salmonella invasion protein A (SipA) promotes gastroenteritis by functional motifs that trigger either mechanisms of inflammation or bacterial entry. During infection of intestinal epithelial cells, SipA was found to be responsible for the early activation of caspase-3, an enzyme that is required for SipA cleavage at a specific recognition motif that divided the protein into its two functional domains and activated SipA in a manner necessary for pathogenicity. Other caspase-3 cleavage sites identified in S. Typhimurium appeared to be restricted to secreted effector proteins, which indicates that this may be a general strategy used by this pathogen for processing of its secreted effectors
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