Multi-scale Modelling of Natural Composites Using Thermodynamics-Based Artificial Neural Networks and Dimensionality Reduction Techniques

Modelling natural composites, as the majority of real geomaterials, requires facing their intrinsic multiscale nature. This allows to consider multiphysics coupling occurring at the microscale, then reflected onto the macroscopic behavior. Geotechnics is constantly requiring reliable constitutive models of natural compolve large-scale engineering problems accurately and efficiently. This need motivates the contribution. To capture in detail the macroscopic effects of microssites to socopic processes, many authors have developed multi-scale numerical schemes. A common drawback of such methods is the prohibitive computational cost. Recently,Machine Learning based approaches have raised as promising alternatives to traditional methods. Artificial Neural Networks – ANNs – have been used to predict the constitutive behaviour of complex, heterogeneous materials, with reduced calculation costs. However, a major weakness of ANN is the lack of a rigorous framework based on principles of physics. This often implies a limited capability to extrapolate values ranging outside the training set and the need of large, high-quality datasets, on which performing the training. This work focuses on the use of Thermodynamics-based Artificial Neural Networks – TANN – to predict the constitutive behaviour of natural composites. Dimensionality reduction techniques – DRTs – are used to embed information of microscopic processes into a lower dimensional manifold. The obtained set of variables is used to characterize the state of the material at the macroscopic scale. Entanglement of DRTs with TANN allows to reproduce the complex nonlinear material response with reduced computational costs and guarantying thermodynamic admissibility. To demonstrate the method capabilities an application to a heterogeneous material model is presented

Immune dyscrasia in adult growth hormone deficiency: Evaluation of hemolytic complement activity (CH50) and IgG subclasses

CH50 is a screening assay for the activation of the classical complement pathway, the immunoglobulins-mediated one, activated in several inflammatory diseases. Adult growth hormone deficiency (aGHD) is recognized as a chronic inflammatory condition, although poorly evaluated under the profile of inflammatory biomarkers. The aim of this case-control observational study is to analyze CH50 and immunoglobulins G (IgG) subclasses production in aGHD, comparing this condition to healthy controls. 38 subjects were included and divided as follows: aGHD (n = 18, 6 females and 12 males); healthy controls (n = 20, 10 females and 10 males). GHD was diagnosed with dynamic test using Growth Hormone-Releasing Hormone (GHRH 50 \u3bcg i.v. + arginine 0,5 g/Kg), with a peak GH response < 9 \u3bcg/L when BMI was <30 kg/m2 or < 4 \u3bcg/L when BMI was >30 kg/m2. The two groups were evaluated for hormonal and metabolic parameters, CH50 and IgG subtypes. IgG1 and IgG2 were significantly higher in controls than in aGHD, while IgG3 and IgG4 showed a trend to higher levels in controls, although not significant. Furthermore, CH50 levels were significantly higher in aGHD. These data substantiate the hypothesis of a dyscrasia in IgG subclasses production in aGHD. As IgG levels decrease, CH50 levels do not

Questions and answers. what can be said by diagnostic imaging in neuroendocrine tumors?

The neuroendocrine tumors (NET) of the gastro-entero-pancreatic area (GEP) represent a heterogeneous group of malignancies from the histologic, clinico-laboratoristic (functioning and non-functioning variants), and therapeutic point of view. It is an issue becoming more frequent for the diagnostic imager, being radiologist as well as nuclear physician. Imaging (together with biopsy) plays a key role in the diagnostic assessment and staging (including grading and prognostic definition), in evaluating response to treatment, and in follow-up of GEP-NET. Multislice computed tomography (MSCT), octreoscan and PET-CT are the most widely diffuse and accurate imaging modalities employed in this setting. Other methods, such as Magnetic Resonance and Endoscopic Ultrasound, may also play a significant role