436 research outputs found
The Governor, the Bishop, and the Patricians: The Contest for the Cathedral Square in Spanish Milan (1535-1706)
In the 16th and 17th centuries, the ambitious reorganization of the urban fabric sponsored and supervised by princes or ruling elites, usually aimed at establishing the power and prestige of the central authority, transformed most Italian cities. However, the separation within the city center between a political and ceremonial space, usually centered around the palace of the prince, and a marketplace, that came to characterize most urban contexts, did not occur in Milan. In order to preserve peace and stability in a period of intense warfare, the monarchy sacrificed an invasive oversight of the city and abdicated a higher degree of local power, choosing instead to delegate it to the urban patriciate, the merchant elites, and the Ambrosian church. Free of any restriction, and in order to preserve their financial interests and emphasize their political prominence, the families of the urban elites maintained the economic function of the area around the cathedral square at the expense of the royal-ducal palace and articulated an alternative power network anchored to their palaces in the residential neighborhoods outside the city center
Fermionic correlations as metric distances : a useful tool for materials science
We introduce a rigorous, physically appealing, and practical way to measure
distances between exchange-only correlations of interacting many-electron
systems, which works regardless of their size and inhomogeneity. We show that
this distance captures fundamental physical features such as the periodicity of
atomic elements, and that it can be used to effectively and efficiently analyze
the performance of density functional approximations. We suggest that this
metric can find useful applications in high-throughput materials design.Comment: 5 pages, 4 figure
A physics-informed generative model for passive radio-frequency sensing
Electromagnetic (EM) body models predict the impact of human presence and
motions on the Radio-Frequency (RF) stray radiation received by wireless
devices nearby. These wireless devices may be co-located members of a Wireless
Local Area Network (WLAN) or even cellular devices connected with a Wide Area
Network (WAN). Despite their accuracy, EM models are time-consuming methods
which prevent their adoption in strict real-time computational imaging problems
and Bayesian estimation, such as passive localization, RF tomography, and
holography. Physics-informed Generative Neural Network (GNN) models have
recently attracted a lot of attention thanks to their potential to reproduce a
process by incorporating relevant physical laws and constraints. Thus, GNNs can
be used to simulate/reconstruct missing samples, or learn physics-informed data
distributions. The paper discusses a Variational Auto-Encoder (VAE) technique
and its adaptations to incorporate a relevant EM body diffraction method with
applications to passive RF sensing and localization/tracking. The proposed
EM-informed generative model is verified against classical diffraction-based EM
body tools and validated on real RF measurements. Applications are also
introduced and discussed
Enhancing Lightpath QoT Computation with Machine Learning in Partially Disaggregated Optical Networks
Increasing traffic demands are causing network operators to adopt disaggregated and open networking solutions to better exploit optical transmission capacity, and consequently enable a software-defined networking (SDN) approach to control and management that encompasses the WDM data transport layer. In these frameworks, a quality of transmission estimator (QoT-E) that gives the generalized signal-to-noise ratio (GSNR) is commonly used to compute the feasibility of transparent lightpaths (LP)s, taking into account the amplified spontaneous emission (ASE) noise and the nonlinear interference (NLI). In general, the ASE noise is the main contributor to the GSNR and is also the most challenging noise component to evaluate in a scenario with varying spectral loads, due to fluctuations in the optical amplifier responses. In this work, we propose a machine learning (ML) algorithm that is trained using different ASE-shaped spectral loads in order to predict the OSNR component of the GSNR; this methodology is subsequently used in combination with a QoT-E in the lightpath computation engine (L-PCE). We present an experiment on a point-to-point optical line system (OLS), including 9 commercial erbium-doped fiber amplifiers (EDFA)s used as black-boxes, each with variable gain and tilt values, and 8 fibers that are characterized by distinct physical parameters. Within this experiment, we receive the signal at the end of the OLS, measuring the bit-error-rate (BER) and the power spectrum, over 2520 different spectral loads. From this dataset, we extract the expected GSNRs and their linear and nonlinear components. Through joint application of a ML algorithm and the open-source GNPy library, we obtain a complete QoT-E, demonstrating that a reliable and accurate LP feasibility predictor may be implemented
Gain profile characterization and modelling for an accurate EDFA abstraction and control
Relying on a two-measurement characterization phase, a gain profile model for
dual-stage EDFAs is presented and validated in full spectral load condition. It
precisely reproduces the EDFA dynamics varying the target gain and tilts
parameters as shown experimentally on two commercial items from different
vendors
Transistors based on the Guanosine molecule (a DNA base)
Abstract Molecules are attractive to develop nano-electronic devices. In this paper a new type of transistor is realized by using self-organized films of the Guanosine molecule, a modified DNA base. With its 40 nm channel length the transistor is a good starting point for a new class of nano-electronics devices. Experimental current-voltage characteristics are shown. A circuital model is also proposed
Site effects on fault-zone : results from ambient noise measurements
It is well known that fault zones are generally characterized by a highly fractured low-velocity belt (damage zone), hundreds of meter wide, bounded by higher-velocity area (host rock) that can broaden for some kilometres (Ben-Zion et al,. 2003; Ben-Zion and Sammis, 2003, 2009 and references therein). Such geometrical setting and impedance contrast is in principle proficient to produce local amplification of ground motion (Peng and Ben-Zion, 2006; Calderoni et al., 2010; Cultrera et al., 2003; Seeber et al., 2000), as well as to support the development of fault zone trapped waves. There is a large number of papers that describe propagation properties of fault-guided waves (e.g., Li et al., 1994; Mizuno, Nishigami, 2006) in terms of ground motion amplification having a propensity to be maximum along the fault-parallel direction. These observations, both in theoretical and experimental approaches deal with almost pure strike slip faults such as the S. Andreas and the Anatolian faults (see Li et al., 2000; Ben Zion et al., 2003). Studies about local seismic response nearby fault zones have been performed in Italy and in California by Cultrera et al. (2003), Calderoni et al. (2010), Pischiutta et al. (2012) who observed evidences of ground motion amplification in the fault zone environments and strong directional effects with high angle to the fault strike. Similar studies, performed by Rigano et al. (2008) and Di Giulio et al. (2009) documented the presence of a systematic polarization of horizontal ground motion, near faults located on the eastern part of the Etnean area, that was never coincident with the strike of the tectonic structures. These directional effects were observed both during local and regional earthquakes, as well as using ambient noise measurements, therefore suggesting the use of microtremors for investigating ground motion polarization properties along and across the main tectonic structures of all the volcanic area. All the observations showed evidence of directional amplifications not parallel to the fault strike, as would have been expected for trapped waves. In the present study, the results of new measurements are shown and discussed. The data were recorded in newly investigated tectonic structures of the volcano located both on the western flank of Mt. Etna (Ragalna fault system) and on the eastern flank of the volcano (Piedimonte fault) as well as in a non-volcanic area (Malta Island), located in the Hyblean foreland. Moreover, several measurements were performed in areas significantly distant from the studied tectonic structures (Piano dei Grilli and Malta area), in order to observe how directional effects can change at increasing distance from the fault lines.peer-reviewe
Isolated hepatocytes versus hepatocyte spheroids: in vitro culture of rat hepatocytes.
The use of hepatocytes that express liver-specific functions to develop an artificial liver is promising. Unfortunately, the loss of specialized liver functions (dedifferentiation) is still a major problem. Different techniques, such as collagen entrapment, spherical multicellular aggregates (spheroids), and coculture of hepatocytes with extracellular matrix, have been used to improve the performance of hepatocytes in culture. The aim of this study was to compare two different models of hepatocyte isolation in culture: isolated hepatocytes (G1) and hepatocyte spheroids (60% hepatocytes, 40% nonparenchymal cells, and extracellular matrix) (G2). To test functional activity of hepatocytes, both synthetic and metabolic, production of albumin and benzodiazepine transformation into metabolites was tested. G2 showed a high albumin secretion, while a decrease after 15 days of culture in G1 was noted. Diazepam metabolites were higher in G2 than in G1 in all samples, but had statistical significance at days 14 and 21 (p < 0.01). The glycogen content, after 30 days of culture, was very low in G1 (14.2 ± 4.4%), while in G2 it was 72.1 ± 2.6% (p < 0.01). Our study confirms the effectiveness of a culture technique with extracellular matrix and nonparenchymal cells. Maintenance of a prolonged functional activity has been related to restoration of cell polarity and close cell-to-cell contact. We showed that isolated hepatocytes maintain their functional activity for a period significantly reduced, when compared to the hepatocyte spheroids. We confirmed the role of extracellular matrix as a crucial component to promote hepatocyte homeostasis, and the close link between cellular architecture and tissue-specific functions
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