21 research outputs found
A new anisotropy index on trabecular bone radiographic images using the fast Fourier transform
BACKGROUND: The degree of anisotropy (DA) on radiographs is related to bone structure, we present a new index to assess DA. METHODS: In a region of interest from calcaneus radiographs, we applied a Fast Fourier Transform (FFT). All the FFT spectra involve the horizontal and vertical components corresponding respectively to longitudinal and transversal trabeculae. By visual inspection, we measured the spreading angles: Dispersion Longitudinal Index (DLI) and Dispersion Transverse Index (DTI) and calculated DA = 180/(DLI+DTI). To test the reliability of DA assessment, we synthesized images simulating radiological projections of periodic structures with elements more or less disoriented. RESULTS: Firstly, we tested synthetic images which comprised a large variety of structures from highly anisotropic structure to the almost isotropic, DA was ranging from 1.3 to 3.8 respectively. The analysis of the FFT spectra was performed by two observers, the Coefficients of Variation were 1.5% and 3.1 % for intra-and inter-observer reproducibility, respectively. In 22 post-menopausal women with osteoporotic fracture cases and 44 age-matched controls, DA values were respectively 1.87 ± 0.15 versus 1.72 ± 0.18 (p = 0.001). From the ROC analysis, the Area Under Curve (AUC) were respectively 0.65, 0.62, 0.64, 0.77 for lumbar spine, femoral neck, total femoral BMD and DA. CONCLUSION: The highest DA values in fracture cases suggest that the structure is more anisotropic in osteoporosis due to preferential deletion of trabeculae in some directions
Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases
The production of peroxide and superoxide is an inevitable consequence of
aerobic metabolism, and while these particular "reactive oxygen species" (ROSs)
can exhibit a number of biological effects, they are not of themselves
excessively reactive and thus they are not especially damaging at physiological
concentrations. However, their reactions with poorly liganded iron species can
lead to the catalytic production of the very reactive and dangerous hydroxyl
radical, which is exceptionally damaging, and a major cause of chronic
inflammation. We review the considerable and wide-ranging evidence for the
involvement of this combination of (su)peroxide and poorly liganded iron in a
large number of physiological and indeed pathological processes and
inflammatory disorders, especially those involving the progressive degradation
of cellular and organismal performance. These diseases share a great many
similarities and thus might be considered to have a common cause (i.e.
iron-catalysed free radical and especially hydroxyl radical generation). The
studies reviewed include those focused on a series of cardiovascular, metabolic
and neurological diseases, where iron can be found at the sites of plaques and
lesions, as well as studies showing the significance of iron to aging and
longevity. The effective chelation of iron by natural or synthetic ligands is
thus of major physiological (and potentially therapeutic) importance. As
systems properties, we need to recognise that physiological observables have
multiple molecular causes, and studying them in isolation leads to inconsistent
patterns of apparent causality when it is the simultaneous combination of
multiple factors that is responsible. This explains, for instance, the
decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference
Présentation des systèmes de petite capacité pour l’épuration des d’eaux urbaines résiduaires.
tude de méthodes et d’outils d’aide à la décision pour la planification et la mise en œuvre de systèmes d’épuration individuelle ou groupé
Choix des filières de traitements des eaux urbaines résiduaires et systèmes d’infiltration d’eaux usées épurées et d’eaux pluviales . Manuel de Projet.
Convention d’étude de méthodes et d’outils d’aide à la décision pour la planification et la mise en œuvre de systèmes d’épuration individuelle ou groupée
Controlled Growth of Gold Nanoparticles Preorganized in Langmuir–Blodgett Monolayers
A method
is described for the in situ growth of substrate-supported
organized gold nanoparticles. Upon exposure to an aqueous solution
of a gold salt and a mild reducing agent, the particle size can be
significantly increased without any loss of superstructure organization.
Furthermore, no secondary nucleation is observed. The surface-supported
regrowth procedure can be combined with the Langmuir–Blodgett
technique to produce a rich library of plasmonic nanoparticle assemblies.
Controlled particle regrowth plays a crucial role in this assembly
method because only relatively small metallic nanoparticles can be
directly dispersed in polymeric Langmuir–Blodgett films. The
versatility of the method is demonstrated through the fabrication
of several specific nanoparticle structures, including contiguous
plasmonic rings, core–satellite structures, and necklace assemblies.
Plasmon extinction spectra are presented for the various nanoparticle
superstructures and illustrate the importance of controlling both
particle size and assembly architecture in achieving targeted optical
properties. The reported approach constitutes a viable bottom-up assembly
route for the fabrication of surface-supported nanoparticle superstructures
for plasmonic applications
Manuel de projet. Choix des filières de traitements des eaux urbaines résiduaires et systèmes d’infiltration d’eaux usées épurées et d’eaux pluviales.
Convention d’étude de méthodes et d’outils d’aide à la décision pour la planification et la mise en œuvre de systèmes d’épuration individuelle ou groupée
Clinical Case of the Month. Acute Methanol Intoxication
peer reviewedWe report a fatal methanol intoxication and discuss its physiopathology, diagnosis and treatment
Exemples d’application de la méthode SAIWE.
Convention d’étude de méthodes et d’outils d’aide à la décision pour la planification et la mise en œuvre de systèmes d’épuration individuelle ou groupé