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SUN
Gricignano di Aversa, Italy

Inheired or acquired hyperhomocysteinemia (HHcy) is associated with several impairments, as certain tumors, deep venous thrombosis, tube neural defects, osteoporosis, early atherosclerosis and vascular acute events (IMA, stroke, PVD), mild cognitive impairments till Alzheimer's disease (AD). But, vascular and neuronal derangements are the most frequent HHcy-manifestations. As far as early atherosclerosis, some clinical trials demonstrated that folates and B 6-12 vitamins SUPPL.ementation is unable to reduce atherosclerotic lesions and cardiovascular events, even if it lowers HHcy levels. Thus, for atherosclerosis and its acute events (IMA, stroke, PVD) HHcy acts as a powerful biomarker rather than a risk factor. For that, the SUPPL.ementation with folates and B vitamins to lower atherosclerotic lesions-events in hyperhomocysteinemic patients is not recommended. On the contrary, several clinical investigations demonstrated that folates and vitamins administration is able to reduce Hcy serum levels and antagonize some mechanisms favouring neurodegenerative impairments, as mild cognitive impairment, AD and dementia. Thus, contrarily to the atherosclerotic manifestations in hyperhomocysteinemic patients, preventive treatment with folates and B6-12 vitamins reduces Hcy concentration and could prevent or delay cognitive decline and AD. © 2012 Springer Science+Business Media New York. Source


Sansone M.,University of Naples Federico II | Fusco R.,University of Naples Federico II | Fusco R.,Italian National Cancer Institute | Petrillo A.,Italian National Cancer Institute | And 2 more authors.
Medical and Biological Engineering and Computing | Year: 2011

Traditionally, tracer kinetic modelling and pixel classification of DCE-MRI studies are accomplished separately, although they could greatly benefit from each other. In this article, we propose an expectation-maximisation scheme for simultaneous pixel classification and compartmental modelling of DCE-MRI studies. The key point in the proposed scheme is the estimation of the kinetic parameters (K trans and K ep) of the two-compartmental model. Typically, they are estimated via nonlinear least-squares fitting. In our scheme, by exploiting the iterative nature of the EM algorithm, we use instead a Taylor expansion of the modelling equation. We developed the theoretical framework for the particular case of two classes and evaluated the performances of the algorithm by means of simulations. Results indicate that the accuracy of the proposed method supersedes the traditional pixel-by-pixel scheme and approaches the theoretical lower bound imposed by the Cramer-Rao theorem. Preliminary results on real data were also reported. © 2010 International Federation for Medical and Biological Engineering. Source


Kruger O.,NMISA | Hungwe F.,NMISA | Farid N.,Nis | Schreve K.,SUN
International Journal of Metrology and Quality Engineering | Year: 2014

At NMISA the SI unit for length is realised by an iodine stabilised He-Ne laser, an optical measurement. In industry most measurements are performed by mechanical probing. Gauge blocks are the link between the optical measurements and the mechanical measurements, and are therefore critical in disseminating traceability. The gauge block length is currently determined by wringing the gauge block onto a platen. This is laborious, requires skill and causes contact errors. Since around 1943, there have been efforts to build a double ended interferometer where gauge block length can be determined without wringing it onto a platen. While there has been a lot of progress in building DEIs, to date, there is still no commercially available DEI. We present a collaboration project between the National Metrology Institute of South Africa (NMISA), the National Institute of Standards (NIS Egypt) and Stellenbosch University (SUN) in South Africa to build a double ended interferometer for use at the respective National Metrology Institutes. We investigate improvements to the interferometric calibration of gauge blocks and recent developments. The different systems currently in use in the national metrology laboratories are described and various designs are investigated. Lastly the expected outcome of the project will be discussed. © 2014 EDP Sciences. Source


Marra F.S.,CNR Institute for Research on Combustion | Acampora L.,SUN | Martelli E.,SUN
International Journal of Spray and Combustion Dynamics | Year: 2015

This paper focus on the behavior of a continuous stirred tank reactor (CSTR) subject to perturbations of finite amplitude and frequency. Two main objectives are pursued: to determine the extinction line in the equivalence ratio (φ) - residence time (τ) plane, fixed the thermodynamic state conditions; and to characterize the response of the chemical system to periodic forcing of the residence time. Transient simulations of combustion of methane with air, using both global single-step and detailed chemical kinetic mechanisms, have been conducted and the corresponding asymptotic solutions analyzed. Results indicate very different dynamical behaviors, posing the issue of a proper choice of the kinetic scheme for the numerical study of combustion oscillations. Source


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Sun | Date: 2005-07-18

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