591 research outputs found

    A review of the perturbation theory as applied to the determination of geopotential

    Get PDF
    Satellite theory to determine geopotential from orbital motion of artificial earth satellite

    “Radar-A-Thon” Concept Paper: RAPHAEL COTS Radar

    Get PDF
    This paper presents a low-cost X-band FMCW radar system suitable for short range sensing in an indoor environment. The design is based on a PLL-VCO architecture, and is realised as a direct conversion receiver. It can achieve range resolutions of 30 cm or 10 cm in standard and ultra- wideband modes respectively. The system is capable of producing programmable linear sweeps over wide bandwidths, and is compliant with FCC Part 15

    Simulation of a finishing operation : milling of a turbine blade and influence of damping

    Get PDF
    Milling is used to create very complex geometries and thin parts, such as turbine blades. Irreversible geometric defects may appear during finishing operations when a high surface quality is expected. Relative vibrations between the tool and the workpiece must be as small as possible, while tool/workpiece interactions can be highly non-linear. A general virtual machining approach is presented and illustrated. It takes into account the relative motion and vibrations of the tool and the workpiece. Both deformations of the tool and the workpiece are taken into account. This allows predictive simulations in the time domain. As an example the effect of damping on the behavior during machining of one of the 56 blades of a turbine disk is analysed in order to illustrate the approach potential

    A study of the degree to which satellite- derived gravitational data can be related to the anomalous surface gravity field and other anomalous geophysical parameters Final report

    Get PDF
    Satellite-derived gravitational data related to anomalous surface gravity field and other geophysical parameters of Solomon Islands are

    A guide to chemokines and their receptors

    Get PDF
    The chemokines (or chemotactic cytokines) are a large family of small, secreted proteins that signal through cell surface G‐protein coupled heptahelical chemokine receptors. They are best known for their ability to stimulate the migration of cells, most notably white blood cells (leukocytes). Consequently, chemokines play a central role in the development and homeostasis of the immune system, and are involved in all protective or destructive immune and inflammatory responses. Classically viewed as inducers of directed chemotactic migration, it is now clear that chemokines can stimulate a variety of other types of directed and undirected migratory behaviour, such as haptotaxis, chemokinesis, and haptokinesis, in addition to inducing cell arrest or adhesion. However, chemokine receptors on leukocytes can do more than just direct migration, and these molecules can also be expressed on, and regulate the biology of, many non‐leukocytic cell types. Chemokines are profoundly affected by post‐translational modification, by interaction with the extracellular matrix (ECM), and by binding to heptahelical ‘atypical’ chemokine receptors that regulate chemokine localisation and abundance. This guide gives a broad overview of the chemokine and chemokine receptor families; summarises the complex physical interactions that occur in the chemokine network; and, using specific examples, discusses general principles of chemokine function, focussing particularly on their ability to direct leukocyte migration

    TLR7 activation at epithelial barriers promotes emergency myelopoiesis and lung antiviral immunity

    Get PDF
    Monocytes are heterogeneous innate effector leukocytes generated in the bone marrow and released into circulation in a CCR2-dependent manner. During infection or inflammation, myelopoiesis is modulated to rapidly meet the demand for more effector cells. Danger signals from peripheral tissues can influence this process. Herein we demonstrate that repetitive TLR7 stimulation via the epithelial barriers drove a potent emergency bone marrow monocyte response in mice. This process was unique to TLR7 activation and occurred independently of the canonical CCR2 and CX3CR1 axes or prototypical cytokines. The monocytes egressing the bone marrow had an immature Ly6C-high profile and differentiated into vascular Ly6C-low monocytes and tissue macrophages in multiple organs. They displayed a blunted cytokine response to further TLR7 stimulation and reduced lung viral load after RSV and influenza virus infection. These data provide insights into the emergency myelopoiesis likely to occur in response to the encounter of single-stranded RNA viruses at barrier sites
    • 

    corecore