The geometric paradigm in computational elasto-plasticity

Computational methods, for large displacements of continua in the elastoplastic range, rely on the mathematical modeling of the nonlinear constitutive behavior. In last decades an increasing favor has been deserved to nonlinear models based on a chain decomposition of the deformation gradient. The troubles involved in a structural analysis based on this model are well-known and have not been overcome although many efforts devoted to this end. Our investigation towards a more satisfactory model starts from the new analysis of the rate elastic behavior performed in [1, 2] since the difficulties faced by previous formulations were the very motivation for the discard of rate constitutive models in elasto-plasticity [3]. The new definition of hypo-elasticity, the detection of simple integrability conditions and a new formulation of conservativeness, lead to a definition of rate elasticity suitable for an effective modeling of rate elasto-plastic constitutive behaviors [4]. The treatment is based on a geometric definition of spatial and material fields and on the statement of a geometric paradigm assessing the rules for comparison of material fields naturally provided by push-pull according to the relevant transformation. The rates involved in constitutive relations are Lie-derivatives of stress field and constitutive parameters. Geometric compatibility requires that elastic and plastic stretchings additively give the Lie-derivative of metric field. No privileged reference configuration is involved and no consequent multiplicative decomposition of deformation gradient is assumed. Computational methods are shown to be based on the pull-back of constitutive relations to a straightened out trajectory segment which plays the role of computation chamber wherein linear operations of differentiation and integration may be performed. Accordingly, finite elastic and plastic stretches are considered as purely computational tools with no physical interpretation in constitutive relations. Both 3-D and lower dimensional structural models, such as wires and membranes, may be analysed by a direct application of the theory. The outcome is a significant improvement of physical insight and computational effectiveness with respect to previous treatments of finite elasto-plasticity

Rats spontaneously perceive global motion direction of drifting plaids

Computing global motion direction of extended visual objects is a hallmark of primate high-level vision. Although neurons selective for global motion have also been found in mouse visual cortex, it remains unknown whether rodents can combine multiple motion signals into global, integrated percepts. To address this question, we trained two groups of rats to discriminate either gratings (G group) or plaids (i.e., superpositions of gratings with different orientations; P group) drifting horizontally along opposite directions. After the animals learned the task, we applied a visual priming paradigm, where presentation of the target stimulus was preceded by the brief presentation of either a grating or a plaid. The extent to which rat responses to the targets were biased by such prime stimuli provided a measure of the spontaneous, perceived similarity between primes and targets. We found that gratings and plaids, when uses as primes, were equally effective at biasing the perception of plaid direction for the rats of the P group. Conversely, for G group, only the gratings acted as effective prime stimuli, while the plaids failed to alter the perception of grating direction. To interpret these observations, we simulated a decision neuron reading out the representations of gratings and plaids, as conveyed by populations of either component or pattern cells (i.e., local or global motion detectors). We concluded that the findings for the P group are highly consistent with the existence of a population of pattern cells, playing a functional role similar to that demonstrated in primates. We also explored different scenarios that could explain the failure of the plaid stimuli to elicit a sizable priming magnitude for the G group. These simulations yielded testable predictions about the properties of motion representations in rodent visual cortex at the single-cell and circuitry level, thus paving the way to future neurophysiology experiments

Truly pattern: Nonlinear integration of motion signals is required to account for the responses of pattern cells in rat visual cortex

A key feature of advanced motion processing in the primate dorsal stream is the existence of pattern cells-specialized cortical neurons that integrate local motion signals into pattern-invariant representations of global direction. Pattern cells have also been reported in rodent visual cortex, but it is unknown whether the tuning of these neurons results from truly integrative, nonlinear mechanisms or trivially arises from linear receptive fields (RFs) with a peculiar geometry. Here, we show that pattern cells in rat primary (V1) and lateromedial (LM) visual cortex process motion direction in a way that cannot be explained by the linear spatiotemporal structure of their RFs. Instead, their tuning properties are consistent with and well explained by those of units in a state-of-the-art neural network model of the dorsal stream. This suggests that similar cortical processes underlay motion representation in primates and rodents. The latter could thus serve as powerful model systems to unravel the underlying circuit-level mechanisms

Effects of nutritional intake on disease severity in children with sickle cell disease.

BACKGROUND: Children with Sickle Cell Disease (SCD) may show growth failure in comparison to healthy peers. Many factors as hematological status, endocrine and/or metabolic dysfunction, and nutritional status, may play an important role in growth failure. The aim of this study was to assess whether impaired growth and nutritional intake can affect SCD severity during childhood. METHODS: We conducted an observational study on children with SCD referring to our clinic for routine follow-up visits in a 6-month period. We collected information on weight, height and body mass index (BMI) and calculated their respective standardized scores (z). The nutritional intake was assessed through the last 24-h recall intake of total calories, macro- (proteins, lipids, carbohydrates) and micronutrients (calcium, iron, phosphorus, vitamins B1, PP, A, C, B2). Disease severity was assessed through total hemoglobin (Hb) and fetal hemoglobin (HbF), and lactic dehydrogenase (LDH) levels, and through the total number and days of hospitalizations, as well as the lifetime episodes of acute chest syndrome (ACS). RESULTS: Twenty nine children (14 males, 15 females) with SCD were enrolled; their mean age was 9.95 years (SD 3.50, min 3.72, max 17.18). Z-weight and z-BMI were significantly directly related to total Hb. Food intake resulted significantly unbalanced in terms of total calorie intake, macro- and micronutrients, especially calcium, iron, vitamin B1 and C. Low intake of calcium and vitamin B1 were significantly inversely correlated with number and days of hospitalizations per year. Protein, lipid, phosphorus, and vitamin PP intakes resulted adequate but were inversely correlated with number and days of hospitalizations. Carbohydrate, lipid, iron, phosphorus, vitamins B1 and B2 intakes were significantly inversely correlated to HbF levels. CONCLUSIONS: This study showed that, in our population, inadequate nutritional intake, weight and BMI have a significant impact on SCD severity indices

Severe impact of Covid-19 pandemic on breast cancer care in Italy: a senonetwork national survey

Italy was the first Western country hit by the Coronavirus disease 2019 (COVID-19) pandemic, with over 246,000 documented cases and more than 35,000 deaths related to the infection as of July 26, 2020. The first documented case in Italy was reported on February 18, 2020, introducing a rapid sequence of events. A few towns near Milan and in Veneto were locked down soon thereafter. Finally, the entire country was locked down on March 9, 2020, with a national quarantine, which has severely limited the movement of the entire population except for documented work and health circumstances. Since then, many hospitals have restrained non-emergency admissions and ambulatory services, particularly for non-oncologic patients. Despite many medical and scientific reports on the current pandemic, little is known on the effect and magnitude of this health emergency on the care of patients with breast cancer

Hierarchical Spatial Organization of Geographical Networks

In this work we propose the use of a hirarchical extension of the polygonality index as a means to characterize and model geographical networks: each node is associated with the spatial position of the nodes, while the edges of the network are defined by progressive connectivity adjacencies. Through the analysis of such networks, while relating its topological and geometrical properties, it is possible to obtain important indications about the development dynamics of the networks under analysis. The potential of the methodology is illustrated with respect to synthetic geographical networks.Comment: 3 page, 3 figures. A wokring manuscript: suggestions welcome

Using salinity to improve nutritional and market value of strawberries

Plants respond to salinity by producing antioxidants and osmolytes; some of these are nutritionally useful to humans (e.g. phenolics), or may improve the sensory quality of produce (e.g. sugars). For the current study, strawberries were irrigated with 0, 10, 20 or 40 mM NaCl, and the responses in antioxidants, phenolics, and flavour attributes were measured. A linear positive relationship was observed between salt stress and antioxidant concentrations, and the DPPH antioxidant assay responded more clearly than the FRAP assay. Phenolics were increased with statistical significance by salinity at all treatment levels, although trends differed between total phenolics and the subclasses anthocyanins and total flavonoids. It was seen that mild salinity (10 mM) with a low impact on yield could be used to increase antioxidants (6-10% above control) and total phenolics (11-16% above control). However differences between cultivars outweighed differences due to salinity in treatments below 20 mM NaCl. We found that sugars in strawberries (unlike other fruits) weren’t increased by salinity treatment. The lack of sugar increase can be explained by suggesting that organic acids are more important osmolytes than sugars for strawberries under salinity. However it was also determined that the failure of strawberries to increase their soluble sugars during salt stress can be explained by the lean nutrient regimes used by researchers, which don’t represent commercial production practices. Practically, mild salinity (≤20 mM) can be used to increase strawberry fruit value, but should be combined with an appropriate nutrient regime to avoid harm to flavour quality. The varieties Elsanta and Elsinore are both suitable for salt treatment, but Elsanta is better for antioxidant and phenolic production, as well as being more salt tolerant

EUSOMA position regarding breast implant associated anaplastic large cell lymphoma (BIA-ALCL) and the use of textured implants

Correction Volume: 48 Pages: 102-102 DOI: 10.1016/j.breast.2019.10.005 Published: DEC 2019During the last two decades the number of breast implants used in aesthetic, oncologic and risk reducing surgery has increased substantially mainly due to the improvement and confirmed safety of these devices. Since identification of the first case of anaplastic large cell lymphoma associated with a breast implant (BIA-ALCL) 20 years ago, there has been an increase in the number of reports of this very rare disease, demonstrating a clear association with breast implants. Whilst the majority of cases are localised and cured by implant removal and full capsulectomy, a small percentage require chemotherapy and the mortality rate is very low. The evidence linking BIA-ALCL to implant surface texturing, as the majority of cases were diagnosed in patients with textured implants, has raised concerns about the long term safety of these devices resulting in patient and regulatory authority concerns globally. We hereby present the current published knowledge about the link between BIA-ALCL and implant surface texture and a review of current regulatory and professional body advice across Europe, which may enable a better understanding of this rare disease, how to manage and ultimately prevent it. We conclude by giving EUSOMA recommendation, towards the unnecessary change in attitudes towards implant based surgery, according to the most recent available published evidence as long as patients are properly informed about the risk of BIA-ALCL. (C) 2019 Elsevier Ltd. All rights reserved.Peer reviewe

A preliminary spectroscopic approach to evaluate the effectiveness of water-and silicone-based cleaning methods on historical varnished brass

Soiling deposition and wrong conservation practices are among the causes of the decay process that can affect the morphological, mechanical, and compositional features of the varnish, the most exposed layer of an artefact. In this perspective, the identification of the best cleaning practices is a priority. During the 18th century, scientific instruments of the highest quality were built, and peculiar varnishes were produced to confer protection and elegance to their metal elements. For this study, based on a historical recipe, we have reproduced a peculiar spirit varnish, enriched with natural resins and colorants, and we have applied on it a synthetic soiling mixture to simulate the aging conditions. We have then performed a non-invasive multi-analytical study to monitor the effectiveness of two water-based and a silicone-based, cleaning methods, namely, water in agarose, Tween 20 (3%) in agarose, and Velvesil Plus. The study includes colorimetry, Fourier transform infrared (FTIR) spectroscopy and X-ray fluorescence (XRF) mapping, coupled with chemometrics. Principal component analysis applied to FTIR spectral data has been demonstrated to be a powerful tool to enhance weak variations in the IR spectra, empowering the interpretation of cleaning effect versus the application time of each cleaning test

Multiscale Bone Remodelling with Spatial P Systems

Many biological phenomena are inherently multiscale, i.e. they are characterized by interactions involving different spatial and temporal scales simultaneously. Though several approaches have been proposed to provide "multilayer" models, only Complex Automata, derived from Cellular Automata, naturally embed spatial information and realize multiscaling with well-established inter-scale integration schemas. Spatial P systems, a variant of P systems in which a more geometric concept of space has been added, have several characteristics in common with Cellular Automata. We propose such a formalism as a basis to rephrase the Complex Automata multiscaling approach and, in this perspective, provide a 2-scale Spatial P system describing bone remodelling. The proposed model not only results to be highly faithful and expressive in a multiscale scenario, but also highlights the need of a deep and formal expressiveness study involving Complex Automata, Spatial P systems and other promising multiscale approaches, such as our shape-based one already resulted to be highly faithful.Comment: In Proceedings MeCBIC 2010, arXiv:1011.005