Sulla genesi della città nell’Italia preromana. Economia, sociologia, urbanistica: il caso dell’insediamento dell’Accesa

The paper opens with a series of passages from ancient historiographic sources on the concept of cities in pre-Roman Italy, on the rite of foundation and on internal urban organization, apart from the vast bibliography. We then focus on the case of the settlement of Accesa (Municipality of Massa Marittima, GR). This is one of several settlements located E and N of Vetulonia, controlled by this same city and connected through by river valleys to areas of mining interest in the district of the Colline Metallifere and the Tyrrhenian coast. Unlike other settlements, where only tombs mostly dating to the Archaic period have been discovered, Accesa has tombs and houses included in a period that ranges from the recent Villanovan to the Archaic. Its main characteristic is the division into distinct neighborhoods, functionalized in the operations that were conducted there: exploitation of mines and metallurgical activity. Their genesis is linked to a number of economic and sociological factors that, integrated together, find an eloquent expression in the urban structure

Investigation of a passive control system for limiting cavitation inside turbomachinery under different operating conditions

Abstract Herein, a new passive control system for limiting cavitation inside turbomachinery has been applied to a NACA0009 hydrofoil. The basic idea is to introduce slots nearby its leading edge, connecting pressure and suction sides of the hydrofoil, in order to increase locally the pressure on its suction side and to prevent cavitation from developing. The cavitating flow developed around a two-dimensional hydrofoil is here considered since it is an archetype of cavitation nearby the leading edges of the impeller vanes. Thus, the flow field developed at the leading edge of both the original and modified hydrofoil has been studied at different angles of attack in order to reproduce a wide range of operating conditions that occur inside turbomachinery. Eventually, a comparison of their performance in terms of polars (C L and C D ) and vapour volume fractions (α v ) is performed

A gray-box model for a probabilistic estimate of regional ground magnetic perturbations: Enhancing the NOAA operational Geospace model with machine learning

We present a novel algorithm that predicts the probability that the time derivative of the horizontal component of the ground magnetic field $dB/dt$ exceeds a specified threshold at a given location. This quantity provides important information that is physically relevant to Geomagnetically Induced Currents (GIC), which are electric currents { associated to} sudden changes in the Earth's magnetic field due to Space Weather events. The model follows a 'gray-box' approach by combining the output of a physics-based model with machine learning. Specifically, we combine the University of Michigan's Geospace model that is operational at the NOAA Space Weather Prediction Center, with a boosted ensemble of classification trees. We discuss the problem of re-calibrating the output of the decision tree to obtain reliable probabilities. The performance of the model is assessed by typical metrics for probabilistic forecasts: Probability of Detection and False Detection, True Skill Statistic, Heidke Skill Score, and Receiver Operating Characteristic curve. We show that the ML enhanced algorithm consistently improves all the metrics considered.Comment: under revie

The Challenge of Machine Learning in Space Weather Nowcasting and Forecasting

The numerous recent breakthroughs in machine learning (ML) make imperative to carefully ponder how the scientific community can benefit from a technology that, although not necessarily new, is today living its golden age. This Grand Challenge review paper is focused on the present and future role of machine learning in space weather. The purpose is twofold. On one hand, we will discuss previous works that use ML for space weather forecasting, focusing in particular on the few areas that have seen most activity: the forecasting of geomagnetic indices, of relativistic electrons at geosynchronous orbits, of solar flares occurrence, of coronal mass ejection propagation time, and of solar wind speed. On the other hand, this paper serves as a gentle introduction to the field of machine learning tailored to the space weather community and as a pointer to a number of open challenges that we believe the community should undertake in the next decade. The recurring themes throughout the review are the need to shift our forecasting paradigm to a probabilistic approach focused on the reliable assessment of uncertainties, and the combination of physics-based and machine learning approaches, known as gray-box.Comment: under revie

ViDA: a VlasovDArwin solver for plasma physics at electron scales

We present a Vlasov–DArwin numerical code (ViDA) specifically designed to address plasma physics problems, where small-scale high accuracy is requested even during the nonlinear regime to guarantee a clean description of the plasma dynamics at fine spatial scales. The algorithm provides a low-noise description of proton and electron kinetic dynamics, by splitting in time the multi-advection Vlasov equation in phase space. Maxwell equations for the electric and magnetic fields are reorganized according to the Darwin approximation to remove light waves. Several numerical tests show that ViDA successfully reproduces the propagation of linear and nonlinear waves and captures the physics of magnetic reconnection. We also discuss preliminary tests of the parallelization algorithm efficiency, performed at CINECA on the Marconi-KNL cluster. ViDA will allow the running of Eulerian simulations of a non-relativistic fully kinetic collisionless plasma and it is expected to provide relevant insights into important problems of plasma astrophysics such as, for instance, the development of the turbulent cascade at electron scales and the structure and dynamics of electron-scale magnetic reconnection, such as the electron diffusion region

Flow non-normality-induced transient growth in superposed Newtonian and non-Newtonian fluid layers

In recent years non-normality and transient growths have attracted much interest in fluid mechanics. Here, we investigate these topics with reference to the problem of interfacial instability in superposed Newtonian and non-Newtonian fluid layers. Under the hypothesis of the lubrication theory, we demonstrate the existence of significant transient growths in the parameter space region where the dynamical system is asymptotically stable, and show how they depend on the main physical parameters. In particular, the key role of the density ratio is highlighte

The Role of Histone H4 Biotinylation in the Structure of Nucleosomes

Background: Post-translational modifications of histones play important roles in regulating nucleosome structure and gene transcription. It has been shown that biotinylation of histone H4 at lysine-12 in histone H4 (K12Bio-H4) is associated with repression of a number of genes. We hypothesized that biotinylation modifies the physical structure of nucleosomes, and that biotin-induced conformational changes contribute to gene silencing associated with histone biotinylation. Methodology/Principal Findings: To test this hypothesis we used atomic force microscopy to directly analyze structures of nucleosomes formed with biotin-modified and non-modified H4. The analysis of the AFM images revealed a 13% increase in the length of DNA wrapped around the histone core in nucleosomes with biotinylated H4. This statistically significant (p,0.001) difference between native and biotinylated nucleosomes corresponds to adding approximately 20 bp to the classical 147 bp length of nucleosomal DNA. Conclusions/Significance: The increase in nucleosomal DNA length is predicted to stabilize the association of DNA with histones and therefore to prevent nucleosomes from unwrapping. This provides a mechanistic explanation for the gene silencing associated with K12Bio-H4. The proposed single-molecule AFM approach will be instrumental for studying the effects of various epigenetic modifications of nucleosomes, in addition to biotinylation

po 237 the pro oncogenic transcription factor stat3 regulates ca2 release and apoptosis from the endoplasmic reticulum via interaction with the ca2 channel ip3r3

Introduction Signal Transducer and Activator of Transcription (STAT) 3 is an oncogenic transcription factor found constitutively activated in several tumours, where it exerts its functions both as a canonical transcription factor and as a non-canonical regulator of energy metabolism and mitochondrial functions. These two activities rely on different post-translational activating events; the phosphorylation on Y705 is involved in nuclear activities, while that on S727 is relevant for mitochondrial functions. Mitochondrial STAT3 increases aerobic glycolysis and decreases ROS production, partly by interacting with the Electron Transfer Complexes (ETC). Material and methods By means of cell fractionations, we tested STAT3 localization to the Endoplasmic Reticulum (ER) in breast cancer cell lines dependent or not on STAT3 activity. We then measured Ca2+ release and apoptotic response in the same cells. The physical interaction between inositol 1,4,5-trisphosphate receptor type 3 (IP3R3) and STAT3 was demonstrated by co-IP either of the endogenous proteins or of their truncated/mutated forms, while STAT3 role in the degradation of IP3R3 was tested by serum starvation and refeeding experiments, followed by WB. Results and discussions We describe here the previously undetected abundant localization of STAT3 also to the ER. In this cellular compartment IP3R3, a Ca2+ channel that allows Ca2+ release from the ER and the mitochondrial associated membranes (MAMs) in response to IP3, regulates the balance between mitochondrial activation and Ca2+-triggered apoptosis. We observed that STAT3 within the ER physically interacts with IP3R3 and, via its phosphorylation on S727, it down-regulates Ca2+ release and apoptosis. Indeed, STAT3 silencing enhances both ER Ca2+ release and sensitivity to apoptosis following oxidative stress in STAT3-dependent mammary tumour cells, correlating with increased IP3R3 levels. In line with this, basal-like breast tumours, which frequently display constitutively active STAT3, show an inverse correlation between IP3R3 and STAT3 protein levels. Conclusion Our results indicate that S727-phosphorylated STAT3 contribute to mammary tumour aggressiveness, also by localising to the ER and regulating Ca2+ fluxes. STAT3-mediated enhanced IP3R3 degradation leads to decreased Ca2+ release and thus to resistance to apoptosis. This new non-canonical STAT3 role appears to be particularly relevant in basal-like breast cancers, adding a new mechanisms through which STAT3 exerts its well established pro-oncogenic anti-apoptotic role