302 research outputs found

    Stiffness and Damping Properties of a Low Aspect Ratio Shear Wall Building Based on Recorded Earthquake Responses

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    An investigation into the structural properties and seismic responses of a low aspect ratio shear wall building, which has construction similarity to typical nuclear plant structures, has been performed using actual recorded earthquake motions. This effort used a combination of modal identification to obtain structure modal parameters directly from the recorded motions, and elastic structural analysis using methods and criteria frequently employed by the nuclear industry. Modal parameters determined by modal identification provide excellent fits to the building motions recorded during the 1984 Morgan Hill earthquake. Modal parameters identified for the 1989 Lorna Prieta earthquake are more uncertain. Investigation of building stiffnesses generally confirms the adequacy of bounding estimates currently recommended for nuclear plant structure seismic analysis. Damping values identified for this building supplement the database being compiled to investigate current nuclear plant structure damping criteria

    Local structure evolution in polycrystalline Zn1−x_{1-x}Mgx_xO (0≤x≤0.150\leq{x}\leq{0.15}) studied by Raman and by synchrotron x-ray pair distribution analysis

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    The local structures of Zn1−x_{1-x}Mgx_xO alloys have been studied by Raman spectroscopy and by synchrotron x-ray pair distribution function (PDF) analysis. Within the solid solution range (0≤x≤0.150\leq{x}\leq{0.15}) of Zn1−x_{1-x}Mgx_xO, the wurtzite framework is maintained with Mg homogeneously distributed throughout the wurtzite lattice. The E2highE_2^\mathrm{high} Raman line of Zn1−x_{1-x}Mgx_xO displays systematic changes in response to the evolution of the crystal lattice upon the Mg-substitution. The red-shift and broadening of the E2highE_2^\mathrm{high} mode are explained by the expansion of hexagonal abab-dimensions, and compositional disorder of Zn/Mg, respectively. Synchrotron x-ray PDF analyses of Zn1−x_{1-x}Mgx_xO reveal that the Mg atoms have a slightly reduced wurtzite parameter uu and more regular tetrahedral bond distances than the Zn atoms. For both Zn and Mg, the internal tetrahedral geometries are independent of the alloy composition.Comment: 10 pages, 12 figures RevTe

    Surpassing the standard quantum limit for optical imaging using nonclassical multimode light

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    Using continuous wave superposition of spatial modes, we demonstrate experimentally displacement measurement of a light beam below the standard quantum limit. Multimode squeezed light is obtained by mixing a vacuum squeezed beam and a coherent beam that are spatially orthogonal. Although the resultant beam is not squeezed, it is shown to have strong internal spatial correlations. We show that the position of such a light beam can be measured using a split detector with an increased precision compared to a classical beam. This method can be used to improve the sensitivity of small displacement measurements

    Secondary influenza challenge triggers resident memory B cell migration and rapid relocation to boost antibody secretion at infected sites.

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    Resident memory B (BRM) cells develop and persist in the lungs of influenza-infected mice and humans; however, their contribution to recall responses has not been defined. Here, we used two-photon microscopy to visualize BRM cells within the lungs of influenza -virus immune and reinfected mice. Prior to re-exposure, BRM cells were sparsely scattered throughout the tissue, displaying limited motility. Within 24 h of rechallenge, these cells increased their migratory capacity, localized to infected sites, and subsequently differentiated into plasma cells. Alveolar macrophages mediated this process, in part by inducing expression of chemokines CXCL9 and CXCL10 from infiltrating inflammatory cells. This led to the recruitment of chemokine receptor CXCR3-expressing BRM cells to infected regions and increased local antibody concentrations. Our study uncovers spatiotemporal mechanisms that regulate lung BRM cell reactivation and demonstrates their capacity to rapidly deliver antibodies in a highly localized manner to sites of viral replication

    The Drosophila Mitochondrial Translation Elongation Factor G1 Contains a Nuclear Localization Signal and Inhibits Growth and DPP Signaling

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    Mutations in the human mitochondrial elongation factor G1 (EF-G1) are recessive lethal and cause death shortly after birth. We have isolated mutations in iconoclast (ico), which encodes the highly conserved Drosophila orthologue of EF-G1. We find that EF-G1 is essential during fly development, but its function is not required in every tissue. In contrast to null mutations, missense mutations exhibit stronger, possibly neomorphic phenotypes that lead to premature death during embryogenesis. Our experiments show that EF-G1 contains a secondary C-terminal nuclear localization signal. Expression of missense mutant forms of EF-G1 can accumulate in the nucleus and cause growth and patterning defects and animal lethality. We find that transgenes that encode mutant human EF-G1 proteins can rescue ico mutants, indicating that the underlying problem of the human disease is not just the loss of enzymatic activity. Our results are consistent with a model where EF-G1 acts as a retrograde signal from mitochondria to the nucleus to slow down cell proliferation if mitochondrial energy output is low

    A putative relay circuit providing low-threshold mechanoreceptive input to lamina I projection neurons via vertical cells in lamina II of the rat dorsal horn

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    Background: Lamina I projection neurons respond to painful stimuli, and some are also activated by touch or hair movement. Neuropathic pain resulting from peripheral nerve damage is often associated with tactile allodynia (touch-evoked pain), and this may result from increased responsiveness of lamina I projection neurons to non-noxious mechanical stimuli. It is thought that polysynaptic pathways involving excitatory interneurons can transmit tactile inputs to lamina I projection neurons, but that these are normally suppressed by inhibitory interneurons. Vertical cells in lamina II provide a potential route through which tactile stimuli can activate lamina I projection neurons, since their dendrites extend into the region where tactile afferents terminate, while their axons can innervate the projection cells. The aim of this study was to determine whether vertical cell dendrites were contacted by the central terminals of low-threshold mechanoreceptive primary afferents. Results: We initially demonstrated contacts between dendritic spines of vertical cells that had been recorded in spinal cord slices and axonal boutons containing the vesicular glutamate transporter 1 (VGLUT1), which is expressed by myelinated low-threshold mechanoreceptive afferents. To confirm that the VGLUT1 boutons included primary afferents, we then examined vertical cells recorded in rats that had received injections of cholera toxin B subunit (CTb) into the sciatic nerve. We found that over half of the VGLUT1 boutons contacting the vertical cells were CTb-immunoreactive, indicating that they were of primary afferent origin. Conclusions: These results show that vertical cell dendritic spines are frequently contacted by the central terminals of myelinated low-threshold mechanoreceptive afferents. Since dendritic spines are associated with excitatory synapses, it is likely that most of these contacts were synaptic. Vertical cells in lamina II are therefore a potential route through which tactile afferents can activate lamina I projection neurons, and this pathway could play a role in tactile allodynia

    Proactive vaccination using multiviral Quartet Nanocages to elicit broad anti-coronavirus responses

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    Defending against future pandemics requires vaccine platforms that protect across a range of related pathogens. Nanoscale patterning can be used to address this issue. Here, we produce quartets of linked receptor-binding domains (RBDs) from a panel of SARS-like betacoronaviruses, coupled to a computationally designed nanocage through SpyTag/SpyCatcher links. These Quartet Nanocages, possessing a branched morphology, induce a high level of neutralizing antibodies against several different coronaviruses, including against viruses not represented in the vaccine. Equivalent antibody responses are raised to RBDs close to the nanocage or at the tips of the nanoparticle’s branches. In animals primed with SARS-CoV-2 Spike, boost immunizations with Quartet Nanocages increase the strength and breadth of an otherwise narrow immune response. A Quartet Nanocage including the Omicron XBB.1.5 ‘Kraken’ RBD induced antibodies with binding to a broad range of sarbecoviruses, as well as neutralizing activity against this variant of concern. Quartet nanocages are a nanomedicine approach with potential to confer heterotypic protection against emergent zoonotic pathogens and facilitate proactive pandemic protection

    Strengthening field-based training in low and middle-income countries to build public health capacity: Lessons from Australia's Master of Applied Epidemiology program

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    BACKGROUND: The International Health Regulations (2005) and the emergence and global spread of infectious diseases have triggered a re-assessment of how rich countries should support capacity development for communicable disease control in low and medium income countries (LMIC). In LMIC, three types of public health training have been tried: the university-based model; streamed training for specialised workers; and field-based programs. The first has low rates of production and teaching may not always be based on the needs and priorities of the host country. The second model is efficient, but does not accord the workers sufficient status to enable them to impact on policy. The third has the most potential as a capacity development measure for LMIC, but in practice faces challenges which may limit its ability to promote capacity development. DISCUSSION: We describe Australia's first Master of Applied Epidemiology (MAE) model (established in 1991), which uses field-based training to strengthen the control of communicable diseases. A central attribute of this model is the way it partners and complements health department initiatives to enhance workforce skills, health system performance and the evidence-base for policies, programs and practice. SUMMARY: The MAE experience throws light on ways Australia could collaborate in regional capacity development initiatives. Key needs are a shared vision for a regional approach to integrate training with initiatives that strengthen service and research, and the pooling of human, financial and technical resources. We focus on communicable diseases, but our findings and recommendations are generalisable to other areas of public health

    The Liquisolid technique: an overview

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    A novel "Powder Solution Technology" involves absorption and adsorption efficiency which makes use of liquid medications, drug suspensions admixed with suitable carriers, coating materials and formulated into free flowing, dry looking, non adherent and compressible powder forms. Based upon a new mathematical model expression, improved flow characteristics and hardness of the formulation has been achieved by changing the proportion of Avicel ® PH 200 and Aerosil ® PH 200 from 50:1 ratio to 5:1 and in which the drug is dispersed in an almost molecularly state. Due to their significantly improved wetting properties a greater drug surface area is exposed to the dissolution media, resulting in an increased dissolution rate and bio availability. By using the Liquisolid technique, sustained drug delivery systems were developed for the water soluble drugs in which hydrophobic non-volatile solvents are used as vehicles.A nova "Tecnologia da Solução Sólida" envolve eficiência de absorção e de adsorção, faz uso de medicações líquidas, suspensões de fármacos e misturas com transportadores adequados, materiais de cobertura e é formulada em formas sólidas em fluxo livre, secas, não aderentes e compressíveis. Com base em novo modelo matemático, características aprimoradas de fluxo e dureza da formulação foram alcançadas modificando-se a proporção de Avicel ® PH 200 e Aerosil ® PH 200 de 50:1 para 5:1, na qual o fármaco é disperso quase que no estado molecular. Devido às propriedades de umidificação significativamente aprimoradas e à área do fármaco exposta ao meio de dissolução, que resulta na velocidade de dissolução, a biodisponibilidade foi aumentada. Utilizando a técnica Liquisólido, desenvolveram-se sistemas de liberação controlada de fármacos solúveis em água, nos quais solventes hidrofóbicos não voláteis foram usados como veículos
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