2,088 research outputs found
Fitness-dependent topological properties of the World Trade Web
Among the proposed network models, the hidden variable (or good get richer)
one is particularly interesting, even if an explicit empirical test of its
hypotheses has not yet been performed on a real network. Here we provide the
first empirical test of this mechanism on the world trade web, the network
defined by the trade relationships between world countries. We find that the
power-law distributed gross domestic product can be successfully identified
with the hidden variable (or fitness) determining the topology of the world
trade web: all previously studied properties up to third-order correlation
structure (degree distribution, degree correlations and hierarchy) are found to
be in excellent agreement with the predictions of the model. The choice of the
connection probability is such that all realizations of the network with the
same degree sequence are equiprobable.Comment: 4 Pages, 4 Figures. Final version accepted for publication on
Physical Review Letter
Patterns of link reciprocity in directed networks
We address the problem of link reciprocity, the non-random presence of two
mutual links between pairs of vertices. We propose a new measure of reciprocity
that allows the ordering of networks according to their actual degree of
correlation between mutual links. We find that real networks are always either
correlated or anticorrelated, and that networks of the same type (economic,
social, cellular, financial, ecological, etc.) display similar values of the
reciprocity. The observed patterns are not reproduced by current models. This
leads us to introduce a more general framework where mutual links occur with a
conditional connection probability. In some of the studied networks we discuss
the form of the conditional connection probability and the size dependence of
the reciprocity.Comment: Final version accepted for publication on Physical Review Letter
Laue Lens Development for Hard X-rays (>60 keV)
Results of reflectivity measurements of mosaic crystal samples of Cu (111)
are reported. These tests were performed in the context of a feasibility study
of a hard X-ray focusing telescope for space astronomy with energy passband
from 60 to 600 keV. The technique envisaged is that of using mosaic crystals in
transmission configuration that diffract X-rays for Bragg diffraction (Laue
lens). The Laue lens assumed has a spherical shape with focal length . It is
made of flat mosaic crystal tiles suitably positioned in the lens. The samples
were grown and worked for this project at the Institute Laue-Langevin (ILL) in
Grenoble (France), while the reflectivity tests were performed at the X-ray
facility of the Physics Department of the University of Ferrara.Comment: 6 pages, 12 figures, accepted for publication in IEEE Transactions on
Nuclear Scienc
Signaling events involved in cytokine and chemokine production induced by secretory phospholipase A2 in human lung macrophages.
7openopenGranata F; Frattini A; Loffredo S; Del Prete A; Sozzani S; Marone G; Triggiani M.Granata, F; Frattini, A; Loffredo, S; DEL PRETE, Annalisa; Sozzani, Silvano; Marone, G; Triggiani, M
Innate immune modulation by GM-CSF and IL-3 in health and disease
Granulocyte-macrophage colony-stimulating factor (GM-CSF) and inteleukin-3 (IL-3) have long been known as mediators of emergency myelopoiesis, but recent evidence has highlighted their critical role in modulating innate immune effector functions in mice and humans. This new wealth of knowledge has uncovered novel aspects of the pathogenesis of a range of disorders, including infectious, neoplastic, autoimmune, allergic and cardiovascular diseases. Consequently, GM-CSF and IL-3 are now being investigated as therapeutic targets for some of these disorders, and some phase I/II clinical trials are already showing promising results. There is also pre-clinical and clinical evidence that GM-CSF can be an effective immunostimulatory agent when being combined with anti-cytotoxic T lymphocyte-associated protein 4 (anti-CTLA-4) in patients with metastatic melanoma as well as in novel cancer immunotherapy approaches. Finally, GM-CSF and to a lesser extent IL-3 play a critical role in experimental models of trained immunity by acting not only on bone marrow precursors but also directly on mature myeloid cells. Altogether, characterizing GM-CSF and IL-3 as central mediators of innate immune activation is poised to open new therapeutic avenues for several immune-mediated disorders and define their potential in the context of immunotherapies
New results on focusing of gamma-rays with Laue lenses
We report on new results on the development activity of broad band Laue
lenses for hard X-/gamma-ray astronomy (70/100-600 keV). After the development
of a first prototype, whose performance was presented at the SPIE conference on
Astronomical Telescopes held last year in Marseille (Frontera et al. 2008), we
have improved the lens assembling technology. We present the development status
of the new lens prototype that is on the way to be assembled.Comment: 8 pages, 11 figures, to be Published in SPIE Proceedings,
vol.7437-19, 200
Innate effector cells in angiogenesis and lymphangiogenesis
Angiogenesis and lymphangiogenesis are distinct and complex processes requiring a finely tuned balance between stimulatory and inhibitory signals. During adulthood, angiogenesis and lymphangiogenesis are activated at sites of tumor growth, tissue injury and remodeling, and chronic inflammation. Vascular endothelial growth factors (VEGFs), angiopoietin (ANGPTs) and a multitude of additional signaling molecules play distinct roles in the modulation of angiogenesis/lymphangiogenesis. VEGFs and ANGPTs activate specific tyrosine kinase receptor (e.g., VEGFR1, VEGFR-2, VEGFR-3 and TIE2 respectively), expressed on blood endothelial cells (angiogenesis) and lymphatic endothelial cells (lymphangiogenesis). Although tumor cells produce VEGFs and other proangiogenic mediators, tissue resident (e.g., macrophages, mast cells) and circulating immune cells (e.g., basophils, neutrophils, monocytes, eosinophils) are an important source of angiogenic/lymphangiogenic mediators in inflammation and in tumor microenvironment and at site of chronic inflammation. Certain immune cells can also release anti-angiogenic factors. Mast cells, basophils, neutrophils and presumably other immune cells are not only a source of angiogenic/lymphangiogenic molecules, but also their target. Cells of the immune system need consideration as major players and possible targets for therapeutic manipulation of angiogenesis/lymphangiogenesis in chronic inflammatory disorders and tumors
Development status of a Laue lens project for gamma-ray astronomy
We report the status of the HAXTEL project, devoted to perform a design study
and the development of a Laue lens prototype. After a summary of the major
results of the design study, the approach adopted to develop a Demonstration
Model of a Laue lens is discussed, the set up described, and some results
presented.Comment: 11 pages, 11 figures, 2007 SPIE Conference on Optics for EUV, X-Ray,
and Gamma-Ray Astronomy II
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