4,149 results on '"Pavesi A"'
Search Results
2. A Silicon Photonic Neural Network for Chromatic Dispersion Compensation in 20 Gbps PAM4 Signal at 125 km and Its Scalability up to 100 Gbps
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Staffoli, Emiliano, Maddinelli, Gianpietro, and Pavesi, Lorenzo
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Computer Science - Emerging Technologies ,Physics - Applied Physics ,Physics - Optics - Abstract
A feed-forward photonic neural network (PNN) is tested for chromatic dispersion compensation in Intensity Modulation/Direct Detection optical links. The PNN is based on a sequence of linear and nonlinear transformations. The linear stage is constituted by an 8-tap time-delayed complex perceptron implemented on a Silicon-On-insulator platform and acting as a tunable optical filter. The nonlinear stage is provided by the square modulus of the electrical field applied at the end-of-line photodetector. The training maximizes the separation between the optical levels (i.e. the eye diagram aperture), with consequent reduction of the Bit Error Rate. Effective equalization is experimentally demonstrated for 20 Gbps 4-level Pulse Amplitude Modulated signal up to 125 km. An evolutionary algorithm and a gradient-based approach are tested for the training and then compared in terms of repeatability and convergence time. The optimal weights resulting from the training are interpreted in light of the theoretical transfer function of the optical fiber. Finally, a simulative study proves the scalability of the layout to larger bandwidths, up to 100 Gbps., Comment: 15 pages, 13 figures
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- 2024
3. Boson Sampling schemes for post-selected multi-photon gates
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Baldazzi, Alessio and Pavesi, Lorenzo
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Quantum Physics - Abstract
We show how to use Boson Sampling schemes in order to create photonic post-selected Controlled-Z and Controlled-Controlled-Z gates, which are equivalent, modulo single-qubit gates, to Controlled-NOT and Toffoli gates, respectively. The new proposed method is based on the following ingredients: identical single photons, Mach-Zehnder interferometer networks, single-photon detectors and post-selection. In particular, by using dual-rail path encoding together with auxiliary paths and single photons, we improve the success probabilities of such gates. This result further proves the complexity and richness of Reck and Clements schemes beyond the usual notions and practices of Boson Sampling., Comment: 23 pages, 6 figures
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- 2024
4. A Systematization of the Wagner Framework: Graph Theory Conjectures and Reinforcement Learning
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Angileri, Flora, Lombardi, Giulia, Fois, Andrea, Faraone, Renato, Metta, Carlo, Salvi, Michele, Bianchi, Luigi Amedeo, Fantozzi, Marco, Galfrè, Silvia Giulia, Pavesi, Daniele, Parton, Maurizio, and Morandin, Francesco
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Computer Science - Machine Learning - Abstract
In 2021, Adam Zsolt Wagner proposed an approach to disprove conjectures in graph theory using Reinforcement Learning (RL). Wagner's idea can be framed as follows: consider a conjecture, such as a certain quantity f(G) < 0 for every graph G; one can then play a single-player graph-building game, where at each turn the player decides whether to add an edge or not. The game ends when all edges have been considered, resulting in a certain graph G_T, and f(G_T) is the final score of the game; RL is then used to maximize this score. This brilliant idea is as simple as innovative, and it lends itself to systematic generalization. Several different single-player graph-building games can be employed, along with various RL algorithms. Moreover, RL maximizes the cumulative reward, allowing for step-by-step rewards instead of a single final score, provided the final cumulative reward represents the quantity of interest f(G_T). In this paper, we discuss these and various other choices that can be significant in Wagner's framework. As a contribution to this systematization, we present four distinct single-player graph-building games. Each game employs both a step-by-step reward system and a single final score. We also propose a principled approach to select the most suitable neural network architecture for any given conjecture, and introduce a new dataset of graphs labeled with their Laplacian spectra. Furthermore, we provide a counterexample for a conjecture regarding the sum of the matching number and the spectral radius, which is simpler than the example provided in Wagner's original paper. The games have been implemented as environments in the Gymnasium framework, and along with the dataset, are available as open-source supplementary materials., Comment: Accepted at the 27th International Conference on Discovery Science http://ds2024.isti.cnr.it/
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- 2024
5. Meta-plasticity and memory in multi-level recurrent feed-forward networks
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Zanardi, Gianmarco, Bettotti, Paolo, Morand, Jules, Pavesi, Lorenzo, and Tubiana, Luca
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Condensed Matter - Disordered Systems and Neural Networks ,Condensed Matter - Statistical Mechanics ,Physics - Biological Physics - Abstract
Network systems can exhibit memory effects in which the interactions between different pairs of nodes adapt in time, leading to the emergence of preferred connections, patterns, and sub-networks. To a first approximation, this memory can be modelled through a ``plastic'' Hebbian or homophily mechanism, in which edges get reinforced proportionally to the amount of information flowing through them. However, recent studies on glia-neuron networks have highlighted how memory can evolve due to more complex dynamics, including multi-level network structures and ``meta-plastic'' effects that modulate reinforcement. Inspired by those systems, here we develop a simple and general model for the dynamics of an adaptive network with an additional meta-plastic mechanism that varies the rate of Hebbian strengthening of its edge connections. Specifically, we consider a biased random walk on a cyclic feed-forward network. The random walk chooses its steps according to the weights of the network edges. The weights evolve through a Hebbian mechanism modulated by a meta-plastic reinforcement, biasing the walker to prefer edges that have been already explored. We study the dynamical emergence (memorization) of preferred paths and their retrieval and identify three regimes: one dominated by the Hebbian term, one in which the meta-reinforcement drives memory formation, and a balanced one. We show that, in the latter two regimes, meta-reinforcement allows for the retrieval of a previously stored path even after weights have been reset to zero to erase Hebbian memory., Comment: 13 pages, 7 figures plus supplementary
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- 2024
6. A linear photonic swap test circuit for quantum kernel estimation
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Baldazzi, Alessio, Leone, Nicolò, Sanna, Matteo, Azzini, Stefano, and Pavesi, Lorenzo
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Quantum Physics ,Physics - Optics - Abstract
Among supervised learning models, Support Vector Machine stands out as one of the most robust and efficient models for classifying data clusters. At the core of this method, a kernel function is employed to calculate the distance between different elements of the dataset, allowing for their classification. Since every kernel function can be expressed as a scalar product, we can estimate it using Quantum Mechanics, where probability amplitudes and scalar products are fundamental objects. The swap test, indeed, is a quantum algorithm capable of computing the scalar product of two arbitrary wavefunctions, potentially enabling a quantum speed-up. Here, we present an integrated photonic circuit designed to implement the swap test algorithm. Our approach relies solely on linear optical integrated components and qudits, represented by single photons from an attenuated laser beam propagating through a set of waveguides. By utilizing 2$^3$ spatial degrees of freedom for the qudits, we can configure all the necessary arrangements to set any two-qubits state and perform the swap test. This simplifies the requirements on the circuitry elements and eliminates the need for non-linearity, heralding, or post-selection to achieve multi-qubits gates. Our photonic swap test circuit successfully encodes two qubits and estimates their scalar product with a measured root mean square error smaller than 0.05. This result paves the way for the development of integrated photonic architectures capable of performing Quantum Machine Learning tasks with robust devices operating at room temperature.
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- 2024
7. Quantum Circuit Mapping for Universal and Scalable Computing in MZI-based Integrated Photonics
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Kwon, Yong, Baldazzi, Alessio, Pavesi, Lorenzo, and Choi, Byung-Soo
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Quantum Physics ,Computer Science - Emerging Technologies - Abstract
Linear optical quantum computing (LOQC) offers a quantum computation paradigm based on well-established and robust technology and flexible environmental conditions following DiVincenzo's criteria. Within this framework, integrated photonics can be utilized to achieve gate-based quantum computing, defining qubits by path-encoding, quantum gates through the use of Mach-Zehnder interferometers (MZIs) as fundamental building blocks, and measurements through single-photon detectors. In particular, universal two-qubit gates can be achieved by suitable structures of MZIs together with post-selection or heralding. The most resource-efficient choice is given by the post-selected CZ gate. However, this implementation is characterized by a design which has a non-regular structure and cannot be cascaded. This limits the implementation of large-scale LOQC. Starting from these issues, we suggest an approach to move toward a universal and scalable LOQC on the integrated photonic platform. First of all, choosing the post-selected CZ as universal two-qubit gate, we extend the path-encoded dual-rail qubit to a triplet of waveguides, composed of an auxiliary waveguide and the pair of waveguides corresponding to the qubit basis states. Additionally, we introduce a swap photonic network that maps the regularly-labeled structure of the new path-encoded qubits to the structure needed for the post-selected CZ. We also discuss the optical swap gate that allows the connection of non-nearest neighbor path-encoded qubits. In this way, we can deterministically exchange the locations of the qubits and execute controlled quantum gates between any path-encoded qubits. Next, by truncating the auxiliary waveguides after any post-selected CZ, we find that it is possible to cascade this optical gate when it acts on different pairs that share only one qubit.
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- 2024
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8. Brillouin nonlinearity characterizations of a high refractive index silicon oxynitride platform
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Ye, Kaixuan, Keloth, Akshay, Klaver, Yvan, Baldazzi, Alessio, Piccoli, Gioele, Sanna, Matteo, Pavesi, Lorenzo, Ghulinyan, Mher, and Marpaung, David
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Physics - Optics ,Physics - Applied Physics - Abstract
Silicon oxynitride (SiON) is a low-loss and versatile material for linear and nonlinear photonics applications. Controlling the oxygen-to-nitrogen (O/N) ratio in SiON provides an effective way to engineer its optical and mechanical properties, making it a great platform for the investigation of on-chip optomechanical interactions, especially the stimulated Brillouin scattering (SBS). Here we report the Brillouin nonlinearity characterization of a SiON platform with a specific O/N ratio (characterized by a refractive index of $n=1.65$). First, we introduce this particular SiON platform with fabrication details. Subsequently, we discuss various techniques for the on-chip Brillouin nonlinearity characterizations. In particular, we focus on the intensity-modulated pump-probe lock-in amplifier technique, which enables ultra-sensitive characterization. Finally, we analyze the Brillouin nonlinearities of this SiON platform and compare them with other SiON platforms. This work underscores the potential of SiON for on-chip Brillouin-based applications. Moreover, it paves the way for Brillouin nonlinearity characterization across various material platforms.
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- 2024
9. SiN integrated photonic components in the Visible to Near-Infrared spectral region
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Sanna, Matteo, Baldazzi, Alessio, Piccoli, Gioele, Azzini, Stefano, Ghulinyan, Mher, and Pavesi, Lorenzo
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Physics - Optics ,Physics - Applied Physics - Abstract
Integrated photonics has emerged as one of the most promising platforms for quantum applications. The performances of quantum photonic integrated circuits (QPIC) necessitate a demanding optimization to achieve enhanced properties and tailored characteristics with more stringent requirements with respect to their classical counterparts. In this study, we report on the simulation, fabrication, and characterization of a series of fundamental components for photons manipulation in QPIC based on silicon nitride. These include crossing waveguides, multimode-interferometer-based integrated beam splitters (MMIs), asymmetric integrated Mach-Zehnder interferometers (MZIs) based on MMIs, and micro-ring resonators. Our investigation revolves primarily around the Visible to Near-Infrared spectral region, as these devices are meticulously designed and tailored for optimal operation within this wavelength range. By advancing the development of these elementary building blocks, we aim to pave the way for significant improvements in QPIC in a spectral region only little explored so far., Comment: 13 pages, 10 figures
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- 2023
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10. Decoding Neuronal Networks: A Reservoir Computing Approach for Predicting Connectivity and Functionality
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Auslender, Ilya, Letti, Giorgio, Heydari, Yasaman, Zaccaria, Clara, and Pavesi, Lorenzo
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Quantitative Biology - Quantitative Methods ,Computer Science - Machine Learning ,Physics - Biological Physics - Abstract
In this study, we address the challenge of analyzing electrophysiological measurements in neuronal networks. Our computational model, based on the Reservoir Computing Network (RCN) architecture, deciphers spatio-temporal data obtained from electrophysiological measurements of neuronal cultures. By reconstructing the network structure on a macroscopic scale, we reveal the connectivity between neuronal units. Notably, our model outperforms common methods like Cross-Correlation and Transfer-Entropy in predicting the network's connectivity map. Furthermore, we experimentally validate its ability to forecast network responses to specific inputs, including localized optogenetic stimuli., Comment: Submitted version
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- 2023
11. Reservoir Computing Model For Multi-Electrode Electrophysiological Data Analysis
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Auslender, Ilya and Pavesi, Lorenzo
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Quantitative Biology - Quantitative Methods ,Computer Science - Emerging Technologies ,Physics - Biological Physics ,Quantitative Biology - Neurons and Cognition - Abstract
In this paper we present a computational model which decodes the spatio-temporal data from electro-physiological measurements of neuronal networks and reconstructs the network structure on a macroscopic domain, representing the connectivity between neuronal units. The model is based on reservoir computing network (RCN) approach, where experimental data is used as training and validation data. Consequently, the model can be used to study the functionality of different neuronal cultures and simulate the network response to external stimuli.
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- 2023
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12. Sorghum Biomass as an Alternative Source for Bioenergy
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Marina Moura Morales, Aaron Kinyu Hoshide, Leticia Maria Pavesi Carvalho, and Flavio Dessaune Tardin
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biomass ,bio-oil ,energy ,eucalyptus ,sorghum ,wood ,Biotechnology ,TP248.13-248.65 - Abstract
Alternative biomass for energy can reduce fossil fuel use and environmental impacts, providing energy security in semi-arid areas with shallow soils that are not ideal for agro-forestry. The densification of sorghum biomass (SB) brings its energetic characteristics closer those of wood. Higher heating value (HHV) represents the heat produced by a given quantity of fuel. This Brazilian research tested different mixtures of SB, eucalyptus wood (W), and eucalyptus bio-oil (Bo) as briquettes for HHV and least ash. Compressed mixtures of SB+B were compared to W+Bo and SB+W+Bo. The concentrations of bio-oil added to SB/W were 1%, 3%, 4%, and 5%. SB+W+Bo composites’ W content was 0%, 25%, 50%, 75%, and 100%, with Bo as 3% of the weight. Sorghum biomass’ HHV is equivalent to W at 3%Bo. Bo doses of 4% and 5% had the same HHV as 3%. Eucalyptus wood did not have a significantly greater HHV with any amount of Bo. SB+W+3%Bo had the same HHV as W when W was at least 50% of the mixture. At greater than 36%W, the ash content was lower than 3%, meeting the EN-B international standard. The optimal composite mixture was 64%SB+36%W+3%Bo for HHV and ash content. SB briquettes can be more widely adopted given sorghum’s prevalence in semi-arid environments.
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- 2024
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13. Narratives and opinion polarization: a survey experiment
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Armenak Antinyan, Thomas Bassetti, Luca Corazzini, and Filippo Pavesi
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Medicine ,Science - Abstract
Abstract We explore the impact of narratives on beliefs and policy opinions through a survey experiment that exposes US subjects to two media-based explanations of the causes of COVID-19. The Lab Narrative ascribes the pandemic to human error and scientific misconduct in a Chinese lab, and the Nature Narrative describes the natural causes of the virus. First, we find that both narratives influence individual beliefs about COVID-19 origins. More precisely, individual beliefs tend to be swayed in the direction of the version of the facts to which one is more exposed generating a potential source of polarization by exposure. Second, only the Nature Narrative unidirectionally affects policy opinions by increasing people’s preferences toward climate protection and trust in science, therefore representing a channel for one-sided polarization by exposure. Finally, we also explore the existence of heterogeneous effects of our narratives, finding that the Lab Narrative leads to opinion polarization between Republican- and Democratic-leaning states on climate change and foreign trade. This indicates the existence of an additional channel that can lead policy opinions to diverge, which we denote polarization by social context.
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- 2024
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14. Photonic neural networks based on integrated silicon microresonators
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Biasi, Stefano, Donati, Giovanni, Lugnan, Alessio, Mancinelli, Mattia, Staffoli, Emiliano, and Pavesi, Lorenzo
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Physics - Optics ,Computer Science - Emerging Technologies - Abstract
The recent progress of artificial intelligence (AI) has boosted the computational possibilities in fields where standard computers are not able to perform. The AI paradigm is to emulate human intelligence and therefore breaks the familiar architecture on which digital computers are based. In particular, neuromorphic computing, artificial neural networks (ANN) and deep learning models mimic how the brain computes. Large networks of interconnected neurons whose synapsis are individually strengthened or weakened during the learning phase find many applications. With this respect, photonics is a suitable platform to implement ANN hardware thanks to its speed, low power dissipation and multi-wavelength opportunities. One photonic device candidate to perform as an optical neuron is the optical microring resonator. Indeed microring resonators show both a nonlinear response and a capability of optical energy storage, which can be interpreted as a fading memory. Moreover, by using silicon photonics, the photonic integrated circuits can be fabricated in volume and with integrated electronics on board. For these reasons, here, we describe the physics of silicon microring resonators and of arrays of microring resonators for application in neuromorphic computing. We describe different types of ANNs from feed-forward networks to photonics extreme learning machines and reservoir computing. In addition, we discuss also hybrid systems where silicon microresonators are coupled to other active materials. this review aims to introduce the basics and to discuss the most recent developments in the field., Comment: 35 pages, 23 figures
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- 2023
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15. Do different kinds of photon-pair sources have the same indistinguishability in quantum silicon photonics?
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Lee, Jong-Moo, Baldazzi, Alessio, Sanna, Matteo, Azzini, Stefano, Ahn, Joon Tae, Lee, Myung Lae, Sohn, Young-Ik, and Pavesi, Lorenzo
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Quantum Physics ,Physics - Optics - Abstract
In the same silicon photonic integrated circuit, we compare two types of integrated degenerate photon-pair sources (microring resonators or waveguides) by means of Hong-Ou-Mandel (HOM) interference experiments. Two nominally identical microring resonators are coupled to two nominally identical waveguides which form the arms of a Mach-Zehnder interferometer. This is pumped by two lasers at two different wavelengths to generate, by spontaneous four-wave mixing, degenerate photon pairs. In particular, the microring resonators can be thermally tuned in or out of resonance with the pump wavelengths, thus choosing either the microring resonators or the waveguides as photon-pair sources, respectively. In this way, an on-chip HOM visibility of 94% with microring resonators and 99% with straight waveguides is measured upon filtering. We compare our experimental results with theoretical simulations of the joint spectral intensity and the purity of the degenerate photon pairs. We verify that the visibility is connected to the sources' indistinguishability, which can be quantified by the overlap between the joint spectral amplitudes (JSA) of the photon pairs generated by the two sources. We estimate a JSAs overlap of 98% with waveguides and 89% with microring resonators.
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- 2023
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16. An array of microresonators as a Photonic Extreme Learning Machine
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Biasi, Stefano, Franchi, Riccardo, Cerini, Lorenzo, and Pavesi, Lorenzo
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Computer Science - Emerging Technologies ,Physics - Optics - Abstract
Machine learning technologies have found fertile ground in optics due to its promising features based on speed and parallelism. Feed-forward neural networks are one of the most widely used machine learning algorithms due to their simplicity and universal approximation capability. However, the typical training procedure, where all weights are optimized, can be time and energy consuming. An alternative approach is the Extreme Learning Machine, a feed-forward neural network in which only the output weights are trained, while the internal connections are random. Here we present an experimental implementation of a photonic extreme learning machine (PELM) in an integrated silicon chip. The PELM is based on the processing of the image of the scattered light by an array of 18 gratings coupled to microresonators. Light propagation in the microresonator array is a linear process while light detection by the video camera is a nonlinear process. Training is done offline by analyzing the recorded scattered light image with a linear classifier. We provide a proof-of-concept demonstration of the PELM by solving both binary and analog tasks, and show how the performance depends on the number of microresonators used in the readout procedure., Comment: 12 pages and 6 figures
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- 2023
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17. Narratives and opinion polarization: a survey experiment
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Antinyan, Armenak, Bassetti, Thomas, Corazzini, Luca, and Pavesi, Filippo
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- 2024
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18. Stem anteversion is not affected by proximal femur geometry in robotic-assisted total hip arthroplasty
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Marcovigi, Andrea, Grandi, Gianluca, Bianchi, Luca, Zambianchi, Francesco, Pavesi, Marco, and Catani, Fabio
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- 2024
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19. Autologous anti-GD2 CAR T cells efficiently target primary human glioblastoma
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Chiavelli, Chiara, Prapa, Malvina, Rovesti, Giulia, Silingardi, Marco, Neri, Giovanni, Pugliese, Giuseppe, Trudu, Lucia, Dall’Ora, Massimiliano, Golinelli, Giulia, Grisendi, Giulia, Vinet, Jonathan, Bestagno, Marco, Spano, Carlotta, Papapietro, Roberto Vito, Depenni, Roberta, Di Emidio, Katia, Pasetto, Anna, Nascimento Silva, Daniela, Feletti, Alberto, Berlucchi, Silvia, Iaccarino, Corrado, Pavesi, Giacomo, and Dominici, Massimo
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- 2024
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20. Generation of quantum-certified random numbers using on-chip path-entangled single photons from an LED
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Leone, Nicolò, Azzini, Stefano, Mazzucchi, Sonia, Moretti, Valter, Sanna, Matteo, Borghi, Massimo, Piccoli, Gioele, Bernard, Martino, Ghulinyan, Mher, and Pavesi, Lorenzo
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Quantum Physics - Abstract
Single-photon entanglement is a peculiar type of entanglement in which two or more degrees of freedom of a single photon are correlated quantum-mechanically. Here, we demonstrate a photonic integrated chip (PIC) able to generate and manipulate single-photon path-entangled states, using a commercial red LED as light source. A Bell test, in the Clauser, Horne, Shimony and Holt (CHSH) form, is performed to confirm the presence of entanglement, resulting in a maximum value of the CHSH correlation parameter equal to $2.605 \pm 0.004$. This allows us to use it as an integrated semi-device independent quantum random number generator able to produce certified random numbers. The certification scheme is based on a Bell's inequality violation and on a partial characterization of the experimental setup, without the need of introducing any further assumptions either on the input state or on the particular form of the measurement observables. In the end a min-entropy of $33\%$ is demonstrated., Comment: 22 pages, 8 figures
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- 2023
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21. Nonlinear response of Silicon Photonics microresonators for reservoir computing neural network
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Staffoli, Emiliano, Bazzanella, Davide, Biasi, Stefano, Donati, Giovanni, Mancinelli, Mattia, Bettotti, Paolo, and Pavesi, Lorenzo
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Computer Science - Emerging Technologies ,Physics - Optics - Abstract
Nowadays, Information Photonics is extensively studied and sees applications in many fields. The interest in this breakthrough technology is mainly stimulated by the possibility of achieving real-time data processing for high-bandwidth applications, still implemented through small-footprint devices that would allow for breaking the limit imposed by Moore's law. One potential breakthrough implementation of information photonics is via integrated photonic circuits. Within this approach, the most suitable computational scheme is achieved by integrated photonic neural networks. In this chapter, we provide a review of one possible way to implement a neural network by using silicon photonics. Specifically, we review the work we performed at the Nanoscience Laboratory of the University of Trento. We present methodologies, results, and future challenges about a delayed complex perceptron for fast data processing, a microring resonator exploiting nonlinear dynamics for a reservoir computing approach, and a microring resonator with the addition of a feedback delay loop for time series processing.
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- 2023
22. The infinity-loop microresonator: A new integrated photonic structure working on an exceptional surface
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Franchi, Riccardo, Biasi, Stefano, Piciocchi, Diego, and Pavesi, Lorenzo
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Physics - Optics - Abstract
Exceptional points, where eigenvalues and eigenvectors coalesce, impact the behavior of different photonics components that show, e.g., enhanced sensing, coherent perfect absorption, unidirectional lasing, and chirality. However, only a few passive geometries have been developed that work on these points. Here, we introduce a novel non-Hermitian structure based on a microresonator shaped as the infinity symbol twice coupled to a bus waveguide: the infinity-loop microresonator. Unlike other structures working on an exceptional surface, the infinity-loop microresonator can achieve either high- or low-contrast unidirectional reflection with a negligible or identical reflection for counterpropagating light. It allows an easy walking through the Riemann sheet by simply controlling the phase of the light propagating in the bus waveguide, which makes it a tunable component to build more complex topological structures. Furthermore, the infinity-loop microresonator allows sensors that show the features of both an exceptional point device and a diabolic point device simultaneously., Comment: 14 pages, 12 figures
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- 2023
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23. Stem anteversion is not affected by proximal femur geometry in robotic-assisted total hip arthroplasty
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Andrea Marcovigi, Gianluca Grandi, Luca Bianchi, Francesco Zambianchi, Marco Pavesi, and Fabio Catani
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Total hip arthroplasty ,Combined anteversion ,Stem anteversion ,Robotic arm-assisted surgery ,Orthopedic surgery ,RD701-811 - Abstract
Abstract Background In the present study, the surgeon aimed to align the stem at 5° to 25° in anteversion. The robotic technology was used to measure stem anteversion with respect to proximal femur anteversion at different levels down the femur. Methods A total of 102 consecutive patients underwent robotic-arm-assisted total hip arthroplasty (RTHA). 3D CT-based preoperative planning was performed to determine femoral neck version (FNV), posterior cortex anteversion (PCA), anterior cortex anteversion (ACA), and femoral metaphyseal axis anteversion (MAA) at 3 different levels: D (10 mm above lesser trochanter), E (the midpoint of the planned neck resection line) and F (head-neck junction). The robotic system was used to define and measure stem anteversion during surgery. Results Mean FNV was 6.6° (SD: 8.8°) and the mean MAA was consistently significantly higher than FNV, growing progressively from proximal to distal. Mean SV was 16.4° (SD: 4.7°). There was no statistically significant difference (P = 0.16) between SV and MAA at the most distal measured level. In 96.1% cases, the stem was positioned inside the 5°–25° anteversion range. Conclusions Femoral anteversion progressively increased from neck to proximal metaphysis. Aligning the stem close to femoral anteversion 10 mm above the lesser trochanter often led to the desired component anteversion.
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- 2024
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24. Blood gases, acid‐base, and metabolic alterations in calves with bronchopneumonia diagnosed via clinical signs and thoracic ultrasonography: A cross‐sectional study
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Antonio Boccardo, Vincenzo Ferrulli, Giulia Sala, Donatella Scavone, Saverio Paltrinieri, Laura Filippone Pavesi, and Davide Pravettoni
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blood gas analysis ,calves ,clinical signs ,respiratory disease ,thoracic ultrasonography ,Veterinary medicine ,SF600-1100 - Abstract
Abstract Background Bronchopneumonia (BP) in calves potentially causes systemic changes. Objectives To describe metabolic, arterial blood gas, and acid‐base disorders in calves with BP diagnosed by thoracic ultrasound (TUS), Wisconsin score (WISC), and combinations of WISC and TUS. Animals Two hundred thirty‐one dairy preweaned dairy calves from 13 dairy farms. Methods Cross‐sectional study. Each calf sequentially underwent arterial blood gas evaluation, WISC score, venous sampling, and TUS. Calves were grouped based on a single diagnostic method and combination of WISC and 2 TUS cutoffs (≥1 cm; ≥3 cm) as healthy, upper respiratory tract infection, subclinical BP, and clinical BP. Results Oxygenation and acid‐base variables were unaffected. Glucose concentration in TUS‐affected calves was significantly lower (P
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- 2024
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25. Equalization of a 10 Gbps IMDD signal by a small silicon photonics time delayed neural network
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Staffoli, Emiliano, Mancinelli, Mattia, Bettotti, Paolo, and Pavesi, Lorenzo
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Computer Science - Emerging Technologies ,Physics - Applied Physics ,Physics - Optics - Abstract
A small 4-channels time-delayed complex perceptron is used as a silicon photonics neural network (NN) device to compensate for chromatic dispersion in optical fiber links. The NN device is experimentally tested with non-return-to-zero optical signals at 10 Gbps after propagation through up to 125 km optical fiber link. During the learning phase, a separation-loss function is optimized in order to maximally separate the transmitted levels of 0s from the 1s, which implies an optimization of the bit-error-rate. Testing of the NN device shows that the excess losses introduced by the NN device are compensated by the gain in transmitted signal equalization for a link longer than 100 km. The measured data are reproduced by a model which accounts for the optical link and the neural network device. This allows simulating the network performances for higher data rates, where the device shows improvement with respect to the benchmark both in terms of performance as well as ease of use., Comment: 14 pages, 6 figures
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- 2023
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26. Detection of the Lassa Virus in a Group of Odontogenic Bone Tumor Tissues
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Marco de Feo, Frédéric Dilu Tamba, Anguy Makaka Mutondo, Gracia Kashitu Mujinga, Opiyo Stephen Odong, Chiara Castellani, Luca Pavesi, Patrick I. Mpingabo, Steve Ahuka-Mundeke, and Silvia Di Agostino
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Lassa virus ,LASV ,arenavirus ,odontogenic fibrous-bone tumor ,ameloblastoma ,Human anatomy ,QM1-695 - Abstract
Odontogenic bone tumor (OT) is a rare pathology in the world, but it is very common in developing countries; its etiology is still unknown, and it causes serious deformities of the mandible and maxilla if it is not operated upon soon. Lassa virus (LASV) belongs to the Arenaviridae family, and its reservoir is a rodent of the genus Mastomys. The transmission of the LASV to humans can occur through ingestion or inhalation by contact with dirty objects, the consumption of contaminated food, or exposure to wounds, as rodents shed the virus in their urine and excrement. In this observational study, we aim to evaluate the presence of LASV in OT patient tissues collected in the Democratic Republic of the Congo. For this purpose, a group of nine patients affected by OT were enrolled, and the tissues derived from the surgery were collected. In total, 81.5% of the tissues were positive for LASV presence. Interestingly, we found that not only was the tumor LASV-positive, but in some cases, the bone was close to the tumor and the oral mucosa lining. These preliminary data could suggest the hypothesis that LASV may be involved with the onset of OT.
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- 2024
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27. Autologous anti-GD2 CAR T cells efficiently target primary human glioblastoma
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Chiara Chiavelli, Malvina Prapa, Giulia Rovesti, Marco Silingardi, Giovanni Neri, Giuseppe Pugliese, Lucia Trudu, Massimiliano Dall’Ora, Giulia Golinelli, Giulia Grisendi, Jonathan Vinet, Marco Bestagno, Carlotta Spano, Roberto Vito Papapietro, Roberta Depenni, Katia Di Emidio, Anna Pasetto, Daniela Nascimento Silva, Alberto Feletti, Silvia Berlucchi, Corrado Iaccarino, Giacomo Pavesi, and Massimo Dominici
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Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract Glioblastoma (GBM) remains a deadly tumor. Treatment with chemo-radiotherapy and corticosteroids is known to impair the functionality of lymphocytes, potentially compromising the development of autologous CAR T cell therapies. We here generated pre-clinical investigations of autologous anti-GD2 CAR T cells tested against 2D and 3D models of GBM primary cells. We detected a robust antitumor effect, highlighting the feasibility of developing an autologous anti-GD2 CAR T cell-based therapy for GBM patients.
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- 2024
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28. Interferometric cavity ring-down technique for ultra-high Q-factor microresonators
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Biasi, Stefano, Franchi, Riccardo, and Pavesi, Lorenzo
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Physics - Optics - Abstract
Microresonators (MRs) are key components in integrated optics. As a result, the estimation of their energy storage capacity as measured by the quality factor (Q) is crucial. However, in MR with high/ultra-high Q, the surface-wall roughness dominates the intrinsic Q and generates a coupling between counter-propagating modes. This splits the usual sharp single resonance and makes difficult the use of classical methods to assess Q. Here, we theoretically show that an interferometric excitation can be exploited in a Cavity Ring-Down (CRD) method to measure the ultimate Q of a MR. In fact, under suitable conditions, the resonant doublet merges into a single Lorentzian and the time dynamics of the MR assumes the usual behavior of a single-mode resonator unaffected by backscattering. This allows obtaining a typical exponential decay in the charging and discharging time of the MR, and thus, estimating its ultimate Q by measuring the photon lifetime., Comment: 5 pages and 2 figures
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- 2022
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29. Silicon oxynitride platform for linear and nonlinear photonics at NIR wavelengths
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Piccoli, Gioele, Sanna, Matteo, Borghi, Massimo, Pavesi, Lorenzo, and Ghulinyan, Mher
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Physics - Optics - Abstract
The development of versatile and novel material platforms for integrated photonics is of prime importance in the perspective of future applications of photonic integrated circuits for quantum information and sensing. Here we present a low-loss material platform based on high-refractive index silicon oxynitride (\ce{SiON}), which offers significant characteristics for linear and non-linear optics applications in a wide range of red/near-infrared wavelengths. The demonstrated propagation loss $<1.5$~dB/cm for visible wavelengths enables the realization of long and intricate circuitry for photon manipulations, as well as the realization of high quality factor resonators. In addition, the proposed \ce{SiON} shows a high nonlinear coefficient of $10^{-19}$~m$^2$/W, improving the strength of nonlinear effects exploitable for on-chip photon generation schemes., Comment: 9 pages, 8 figures
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- 2022
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30. Antibiotic residues in dairy products in Africa: A systematic review
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Emelda Orlando Simbine-Ribisse, Níura Madalena Bila, Agnaldo Joaquim Manhiça, Cristiano João Macuamule, and Adriana Pavesi Arisseto Bragotto
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Veterinary drugs ,Milk ,Detection techniques ,Food safety ,Africa ,Food processing and manufacture ,TP368-456 - Abstract
The improper use of antibiotics in animal production in Africa may result in antibiotic residues (AR's) in food, and it represents a risk to public health. However, there is scarce information on the rate of AR's in dairy products. This systematic review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The information was collected from databases Web of Science, Science Direct, PubMed, Google Scholar, PAMJ One Health, ResearchGate, and selected African journals. A total of 359 articles were identified and only 22 studies were included. In total, 6246 dairy samples were analyzed, with raw milk as the main sample (90.7 %). Among the 39 antibiotics recorded, the most detected were penicillin, ampicillin, amoxicillin, oxytetracycline, tetracycline, and chlortetracycline. The highest residue rates (90.38 %) were found for dicloxacillin, cefazolin, cefoperazone, cefaclor, and spiramycin. The most used techniques for antibiotic detection were Delvotest, high-performance liquid chromatography coupled to ultra-violet, and liquid chromatography coupled with mass spectrometry in tandem. AR's are high in raw milk and above the Maximum Residues Level representing a big challenge for Africa. Establishing AR's control plans in Africa could be a good strategy to improve the monitoring of their occurrence in food.
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- 2024
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31. Quantum states generation and manipulation in a programmable silicon-photonic four-qubit system with high-fidelity and purity
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Jong-Moo Lee, Jiho Park, Jeongho Bang, Young-Ik Sohn, Alessio Baldazzi, Matteo Sanna, Stefano Azzini, and Lorenzo Pavesi
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Applied optics. Photonics ,TA1501-1820 - Abstract
We present a programmable silicon photonic four-qubit integrated circuit for the generation and manipulation of diverse quantum states. The silicon photonic chip integrates photon-pair sources, pump-reducing filters, wavelength-division-multiplexing filters, Mach–Zehnder interferometer switches, and single-qubit arbitrary gates, enabling versatile state preparation and tomography. We measure Hong–Ou–Mandel interference with an impressive 98% visibility using four-photon coincidence, laying the foundation for high-purity qubits. Our analysis involves estimating the fidelity and purity of distinct quantum states through maximum-likelihood estimation applied to tomographic measurements. In our experimental results, we showcase the following achievements: a heralded single qubit achieving 98.2% fidelity and 98.3% purity, a Bell state reaching 95.2% fidelity and 94.8% purity, and a four-qubit system with two simultaneous Bell states exhibiting 87.4% fidelity and 84.6% purity. Finally, a four-qubit Greenberger–Horne–Zeilinger (GHZ) state demonstrates 85.4% fidelity and 81.7% purity. In addition, we certify the entanglement of the four-photon GHZ state through Bell’s inequality violations and a negative entanglement witness.
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- 2024
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32. Potential use of pineapple crop residue silage to replace sorghum silage for crossbred lactating cows
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Helenita Bárbara Fonseca Silva, Bruna Cardoso Braga, Severino Delmar Junqueira Villela, Raphael Pavesi Araújo, Raphael dos Santos Gomes, Maria Eduarda Lara Resende, Guilherme Campos Leitão, and Fernando de Paula Leonel
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By-products ,Milk quality ,Milk yield ,Pineapple silage ,Ruminants. ,Agriculture (General) ,S1-972 - Abstract
The use of crop residue silages is a viable alternative for producers to reduce feed costs. The present study was developed with the objective of investigating the inclusion of pineapple silage in replacement of sorghum silage in the diet of lactating cows regarding feed intake, production, and quality of milk. Eight crossbred (Holstein × Gir) cows with an average weight of 555±30 kg and an average milk yield of 12.50±3.25 kg/day, between 60 and 90 days in milk, were distributed into two simultaneous 4 × 4 Latin squares, at one animal per experimental unit. Silage of pineapple crop residue (PS) using plants after the harvest of the fruits was included in the roughage portion of the diet at increasing levels, with simultaneous and proportional removal of sorghum silage (SS) from the diets. The studied treatments thus consisted of the roughage portion containing: 1- 0% PS and 100% SS (100SS); 2- 34% PS and 66% SS (34PS66SS); 3- 67% PS and 33% SS (67PS33SS); 4- 100% PS and 0% SS (100PS). The diets were supplied twice daily, allowing 5% leftovers in relation to the quantity offered. The amounts of feed supplied, and orts of each animal were weighed for a subsequent determination of intake. The experiment was divided into four 21-day sub-periods, the first 14 days of which were used as an adaptation to the diet, while the others served for data collection. The milk was weighed from the 15th to the 19th day of each experimental period, and milk samples were collected on the last day of each period. Milk samples were sent to the laboratory, where they were analyzed. Dry matter, mineral matter, and lignin concentrations in the diet did not vary (P>0.05) as a function of PS inclusion in the roughage portion, while protein content, fiber content, and fat content levels were influenced. No effect of PS inclusion was observed (P>0.05) on the intakes of dry matter, neutral detergent fiber, mineral material, or lignin. However, PS inclusion prompted (P
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- 2024
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33. A Mindfulness-Based App Intervention for Pregnant Women: Protocol for a Pilot Feasibility Study
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Silvia Rizzi, Stefania Poggianella, Maria Chiara Pavesi, Lorenzo Gios, Giorgia Bincoletto, Isabella Scolari, Claudia Paoli, Debora Marroni, Irene Tassinari, Barbara Baietti, Anna Gianatti, Veronica Albertini, Barbara Burlon, Vanda Chiodega, Barbara Endrizzi, Elena Benini, Chiara Guella, Erik Gadotti, Stefano Forti, and Fabrizio Taddei
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Medicine ,Computer applications to medicine. Medical informatics ,R858-859.7 - Abstract
BackgroundPregnancy is a complex time characterized by major transformations in a woman, which impact her physical, mental, and social well-being. How a woman adapts to these changes can affect her quality of life and psychological well-being. The literature indicates that pregnant women commonly experience psychological symptoms, with anxiety, stress, and depression being among the most frequent. Hence, promoting a healthy lifestyle focused on women’s psychological well-being is crucial. Recently developed digital solutions have assumed a crucial role in supporting psychological well-being in physiologically pregnant women. Therefore, the need becomes evident for the development and implementation of digital solutions, such as a virtual coach implemented in a smartphone, as a support for the psychological well-being of pregnant women who do not present psychological and psychiatric disorders. ObjectiveThis study aims to assess the feasibility, acceptability, and utility of a mindfulness-based mobile app. The primary objective is to explore the feasibility of using a virtual coach, Maia, developed within the TreC Mamma app to promote women’s psychological well-being during pregnancy through a psychoeducational module based on mindfulness. Finally, through the delivery of this module, the level of psychological well-being will be explored as a secondary objective. MethodsThis is a proof-of-concept study in which a small sample (N=50) is sufficient to achieve the intended purposes. Recruitment will occur within the group of pregnant women belonging to the pregnancy care services of the Trento Azienda Provinciale per i Servizi Sanitari di Trento. The convenience sampling method will be used. Maia will interact with the participating women for 8 weeks, starting from weeks 24 and 26 of pregnancy. Specifically, there will be 2 sessions per week, which the woman can choose, to allow more flexibility toward her needs. ResultsThe psychoeducational pathway is expected to lead to significant results in terms of usability and engagement in women’s interactions with Maia. Furthermore, it is anticipated that there will be improvements in psychological well-being and overall quality of life. The analysis of the data collected in this study will be mainly descriptive, orientated toward assessing the achievement of the study objectives. ConclusionsLiterature has shown that women preferred web-based support during the perinatal period, suggesting that implementing digital interventions can overcome barriers to social stigma and asking for help. Maia can be a valuable resource for regular psychoeducational support for women during pregnancy. International Registered Report Identifier (IRRID)RR1-10.2196/53890
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- 2024
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34. A Microring as a Reservoir Computing Node: Memory/Nonlinear Tasks and Effect of Input Non-ideality
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Bazzanella, Davide, Biasi, Stefano, Mancinelli, Mattia, and Pavesi, Lorenzo
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Computer Science - Emerging Technologies ,Physics - Optics - Abstract
The nonlinear response of an optical microresonator is used in a time multiplexed reservoir computing neural network. Within a virtual node approach combined with an offline training through ridge regression, we solved linear and nonlinear logic operations. We analyzed the nonlinearity of the microresonator as a memory between bits and/or as a neural activation function. This is made possible by controlling both the distance between bits subject to the logical operation and the number of bits supplied to the ridge regression. We show that the optical microresonator exhibits up to two bits of memory in linear tasks and that it allows solving nonlinear tasks providing both memory and nonlinearity. Finally, we demonstrate that the virtual node approach always requires a comparison of the reservoir's performance with the results obtained by applying the same training process on the input signal., Comment: 11 pages, 8 figures
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- 2022
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35. Genomic binding of NF-Y in mouse and human cells
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Ronzio, Mirko, Bernardini, Andrea, Taglietti, Valentina, Ceribelli, Michele, Donati, Giacomo, Gallo, Alberto, Pavesi, Giulio, Dellabona, Paolo, Casorati, Giulia, Messina, Graziella, Mantovani, Roberto, and Dolfini, Diletta
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- 2024
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36. NOR TECHNOPHILIA OR TECHNOPHOBIA: CONTRIBUTIONS TO A DISCOURSE THE REALIZATION OF PERSONALITY RIGHTS/NEM TECNOFILIA OU TECNOFOBIA: CONTRIBUTOS PARA UM DISCURSO CONVERGENTE A EFETIVACAO DOS DIREITOS DA PERSONALIDADE/NI TECNOFILIA NI TECNOFOBIA: APORTES A UN DISCURSO CONVERGENTE SOBRE LA IMPLEMENTACION DE LOS DERECHOS DE LA PERSONALIDAD
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Siqueira, Dirceu Pereira and Lara, Fernanda Correa Pavesi
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- 2023
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37. Mitigating indistinguishability issues in photon pair sources by delayed-pump Intermodal Four Wave Mixing
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Borghi, Massimo and Pavesi, Lorenzo
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Quantum Physics - Abstract
Large arrays of independent, pure and identical heralded single photon sources are ubiquitous in today's Noise Intermediate Scale Quantum devices (NISQ). In the race towards the development of increasingly ideal sources, delayed-pump Intermodal Four Wave Mixing (IFWM) in multimode waveguides has recently demonstrated record performances in all these metrics, becoming a benchmark for spontaneous sources in integrated optics. Despite this, fabrication imperfections still spoil the spectral indistinguishability of photon pairs from independent sources. Here we show that by tapering the width of the waveguide and by controlling the delay between the pump pulses, we add spectral tunability to the source while still inheriting all the record metrics of the IFWM scheme. This feature is used to recover spectral indistinuishability in presence of fabrication errors. Under realistic tolerances on the waveguide dimensions, we predict >99.5% indistinguishability between independent sources on the same chip, and a maximum degradation of the Heralded Hong Ou Mandel visibility <0.35 %.
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- 2022
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38. Longitudinal Neuropsychological Assessment of Symptomatic Edema after Subthalamic Nucleus Deep Brain Stimulation Surgery: A Case Series Study
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Silvia De Ieso, Giulia Di Rauso, Francesco Cavallieri, Daniela Beltrami, Alessandro Marti, Manuela Napoli, Rosario Pascarella, Alberto Feletti, Valentina Fioravanti, Giulia Toschi, Vittorio Rispoli, Francesca Antonelli, Annette Puzzolante, Giacomo Pavesi, Federico Gasparini, and Franco Valzania
- Subjects
edema ,deep brain stimulation DBS ,neuropsychological ,subthalamic nucleus ,STN-DBS ,Medicine ,Internal medicine ,RC31-1245 ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Severe non-infectious or non-haemorrhagic brain edema surrounding the electrode represents a rare complication of subthalamic nucleus deep brain stimulation (STN-DBS) surgery. The aim of this study is to report three patients with advanced Parkinson’s Disease (PD) who developed symptomatic brain edema after STN-DBS surgery treated with intravenous steroids with a specific profile of reversible cognitive alterations. Patients were both assessed with a comprehensive neuropsychological battery including attention, memory, visuo-spatial and executive tasks. They were also briefly assessed for emotional and behavioural alterations, and for possible limitations in the activities of daily living. Normative data for an Italian population were available for all neuropsychological tests. The patients were firstly assessed before the surgery (baseline) as soon as they became symptomatic for the post-surgery edema and a few more times in follow-up up to ten months. In all patients we observed the resolution of cognitive deficits within six months after surgery with the corresponding reabsorption of edema at brain CT scans. The appearance of post-DBS edema is a fairly frequent and clinically benign event. However, in some rare cases it can be very marked and lead to important clinical—albeit transient—disturbances. These events can compromise, at least from a psychological point of view, the delicate path of patients who undergo DBS and can prolong the post-operative hospital stay. In this setting it could be helpful to perform a brain CT scan in 2–3 days with the aim of detecting the early appearance of edema and treating it before it can constitute a relevant clinical problem.
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- 2023
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39. Impact of chitosan-incorporated toothpaste on roughness, gloss, and antifungal potential of acrylic resin
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Kaye Varaschin Theodorovicz, Waldemir Franscisco Vieira-Junior, Raissa Manoel Garcia, Ludmila Pini Simões Gobbi, Mariana Mayume Mori, Benedito Prado Dias Filho, Débora Alves Nunes Leite Lima, Daniel Sundfeld, and Núbia Inocencya Pavesi Pini
- Subjects
Medicine ,Science - Abstract
Abstract This study aimed to test the efficacy of different silica-based toothpastes with or without chitosan, as a method of cleaning the acrylic surfaces of denture prostheses. Acrylic resin specimens were prepared to evaluate surface roughness and gloss (n = 10), and Candida albicans adhesion/inhibition (n = 2). Two toothpastes with different degrees of abrasiveness were used: Colgate (CT) and Elmex (EX), with or without 0.5% chitosan (Ch) microparticles (CTCh or EXCh, respectively). The negative control was brushed with distilled water. Brushing was simulated with a machine. Surface roughness and gloss were analyzed before and after brushing. Candida albicans incidence/inhibition was tested qualitatively to determine the acrylic resin antifungal activity. The roughness and gloss data were analyzed with a generalized linear model, and the Kruskal Wallis and Dunn tests, respectively (α = 5%). Brushing with toothpastes increased roughness and reduced gloss, compared with the negative control (p
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- 2023
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40. Molecular Gas Excitation of the Massive Dusty Starburst CRLE and the Main-Sequence Galaxy HZ10 at z=5.7 in the COSMOS Field
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Vieira, Daniel, Riechers, Dominik A., Pavesi, Riccardo, Faisst, Andreas L., Schinnerer, Eva, Scoville, Nicholas Z., and Stacey, Gordon J.
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Astrophysics - Astrophysics of Galaxies - Abstract
We report CO(5$\rightarrow$4) and CO(6$\rightarrow$5) line observations in the dusty starbursting galaxy CRLE ($z = 5.667$) and the main-sequence (MS) galaxy HZ10 ($z = 5.654$) with the Northern Extended Millimeter Array (NOEMA). CRLE is the most luminous $z>5$ starburst in the COSMOS field and HZ10 is the most gas-rich "normal" galaxy currently known at $z>5$. We find line luminosities for CO(5$\rightarrow$4) and CO(6$\rightarrow$5) of (4.9 $\pm$ 0.5) and (3.8 $\pm$ 0.4) $\times$ 10$^{10}$ K km s$^{-1}$ pc$^{2}$ for CRLE and upper limits of $< 0.76$ and $< 0.60$ $\times$ 10$^{10}$ K km s$^{-1}$ pc$^{2}$ for HZ10, respectively. The CO excitation of CRLE appears comparable to other $z>5$ dusty star-forming galaxies (DSFGs). For HZ10, these line luminosity limits provide the first significant constraints of this kind for a MS galaxy at $z > 5$. We find the upper limit of $L'_{5\rightarrow4}/L'_{2\rightarrow1}$ in HZ10 could be similar to the average value for MS galaxies around $z\approx 1.5$, suggesting that MS galaxies with comparable gas excitation may already have existed one billion years after the Big Bang. For CRLE we determine the most likely values for the H$_2$ density, kinetic temperature and dust temperature based on excitation modeling of the CO line ladder. We also derive a total gas mass of $(7.1 \pm 1.3) \times 10^{10} M_\odot$. Our findings provide some of the currently most detailed constraints on the gas excitation that sets the conditions for star formation in a galaxy protocluster environment at $z > 5$., Comment: 14 pages, 6 figures, accepted to ApJ
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- 2021
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41. An interferometric method to estimate the eigenvalues of a Non-Hermitian two-level optical system
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Biasi, Stefano, Franchi, Riccardo, Mione, Filippo, and Pavesi, Lorenzo
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Physics - Optics - Abstract
Non-Hermitian physics has found a fertile ground in optics. Recently, the study of mode degeneracies, i.e. exceptional points, has led to the discovery of intriguing and counterintuitive phenomena. Degeneracies are typically modeled through the coupled mode theory to determine the behaviour of eigenstates and eigenvalues. However, the complex nature of the eigenvalues makes hard their direct characterization from the response spectrum. Here, we demonstrate that a coherent interferometric excitation allows estimating both the real and imaginary parts of the eigenvalues. We studied the clockwise and counter-clockwise modes in an optical microresonators both in the case of Hermitian and non-Hermitian intermodal coupling. We show the conditions by which a resonant doublet, due to the dissipative coupling of counter-propagating modes caused by surface roughness backscattering, merges to a single Lorentzian. This permits to estimate the optimal quality factor of the microresonator in the absence of modal coupling caused by backscattering. Furthermore, we demonstrate that a taiji microresonator working at an exceptional point shows a degeneracy splitting only in one propagation direction and not in the other. This follows from the strongly non-Hermitian intermodal coupling caused by the inner S-shaped waveguide., Comment: 13 pages and 8 figures
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- 2021
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42. COLDz: Probing Cosmic Star Formation With Radio Free-free Emission
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Algera, Hiddo S. B., Hodge, Jacqueline A., Riechers, Dominik A., Leslie, Sarah K., Smail, Ian, Aravena, Manuel, da Cunha, Elisabete, Daddi, Emanuele, Decarli, Roberto, Dickinson, Mark, Gim, Hansung B., Guaita, Lucia, Magnelli, Benjamin, Murphy, Eric J., Pavesi, Riccardo, Sargent, Mark T., Sharon, Chelsea E., Wagg, Jeff, Walter, Fabian, and Yun, Min
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
Radio free-free emission is considered to be one of the most reliable tracers of star formation in galaxies. However, as it constitutes the faintest part of the radio spectrum -- being roughly an order of magnitude less luminous than radio synchrotron emission at the GHz frequencies typically targeted in radio surveys -- the usage of free-free emission as a star formation rate tracer has mostly remained limited to the local Universe. Here we perform a multi-frequency radio stacking analysis using deep Karl G. Jansky Very Large Array observations at 1.4, 3, 5, 10 and 34 GHz in the COSMOS and GOODS-North fields to probe free-free emission in typical galaxies at the peak of cosmic star formation. We find that $z \sim 0.5 - 3$ star-forming galaxies exhibit radio emission at rest-frame frequencies of $\sim 65 - 90$ GHz that is $\sim 1.5 - 2\times$ fainter than would be expected from a simple combination of free-free and synchrotron emission, as in the prototypical starburst galaxy M82. We interpret this as a deficit in high-frequency synchrotron emission, while the level of free-free emission is as expected from M82. We additionally provide the first constraints on the cosmic star formation history using free-free emission at $0.5 \lesssim z \lesssim 3$, which are in good agreement with more established tracers at high redshift. In the future, deep multi-frequency radio surveys will be crucial in order to accurately determine the shape of the radio spectrum of faint star-forming galaxies, and to further establish radio free-free emission as a tracer of high-redshift star formation., Comment: Accepted for publication in ApJ; 22 pages + appendices, 11 figures in main text
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- 2021
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43. Physical Properties of an Efficient MAPbBr3/GaAs Hybrid Heterostructure for Visible/Near-Infrared Detectors
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Tarek Hidouri, Maura Pavesi, Marco Vaccari, Antonella Parisini, Nabila Jarmouni, Luigi Cristofolini, and Roberto Fornari
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hybrid materials ,GaAs ,perovskites ,MAPbBr3 ,photodetection ,integration ,Chemistry ,QD1-999 - Abstract
Semiconductor photodetectors can work only in specific material-dependent light wavelength ranges, connected with the bandgaps and absorption capabilities of the utilized semiconductors. This limitation has driven the development of hybrid devices that exceed the capabilities of individual materials. In this study, for the first time, a hybrid heterojunction photodetector based on methylammonium lead bromide (MAPbBr3) polycrystalline film deposited on gallium arsenide (GaAs) was presented, along with comprehensive morphological, structural, optical, and photoelectrical investigations. The MAPbBr3/GaAs heterojunction photodetector exhibited wide spectral responsivity, from 540 to 900 nm. The fabrication steps of the prototype device, including a new preparation recipe for the MAPbBr3 solution and spinning, will be disclosed and discussed. It will be shown that extending the soaking time and refining the precursor solution’s stoichiometry may enhance surface coverage, adhesion to the GaAs, and film uniformity, as well as provide a new way to integrate MAPbBr3 on GaAs. Compared to the pristine MAPbBr3, the enhanced structural purity of the perovskite on GaAs was confirmed by X-ray Diffraction (XRD) upon optimization compared to the conventional glass substrate. Scanning Electron Microscopy (SEM) revealed the formation of microcube-like structures on the top of an otherwise continuous MAPbBr3 polycrystalline film, with increased grain size and reduced grain boundary effects pointed by Energy-Dispersive Spectroscopy (EDS) and cathodoluminescence (CL). Enhanced absorption was demonstrated in the visible range and broadened photoluminescence (PL) emission at room temperature, with traces of reduction in the orthorhombic tilting revealed by temperature-dependent PL. A reduced average carrier lifetime was reduced to 13.8 ns, revealed by time-resolved PL (TRPL). The dark current was typically around 8.8 × 10−8 A. Broad photoresponsivity between 540 and 875 nm reached a maximum of 3 mA/W and 16 mA/W, corresponding to a detectivity of 6 × 1010 and 1 × 1011 Jones at −1 V and 50 V, respectively. In case of on/off measurements, the rise and fall times were 0.40 s and 0.61 s or 0.62 s and 0.89 s for illumination, with 500 nm or 875 nm photons, respectively. A long-term stability test at room temperature in air confirmed the optical and structural stability of the proposed hybrid structure. This work provides insights into the physical mechanisms of new hybrid junctions for high-performance photodetectors.
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- 2024
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44. Antibiotic residues in dairy products in Africa: A systematic review
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Simbine-Ribisse, Emelda Orlando, Bila, Níura Madalena, Manhiça, Agnaldo Joaquim, Macuamule, Cristiano João, and Bragotto, Adriana Pavesi Arisseto
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- 2024
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45. Microring resonators with external optical feedback for time delay reservoir computing
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Donati, Giovanni, Mirasso, Claudio R., Mancinelli, Mattia, Pavesi, Lorenzo, and Argyris, Apostolos
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Physics - Optics ,Electrical Engineering and Systems Science - Signal Processing - Abstract
Microring resonators (MRRs) are a key photonic component in integrated devices, due to their small size, low insertion losses, and passive operation. While the MRRs have been established for optical filtering in wavelength-multiplexed systems, the nonlinear properties that they can exhibit give rise to new perspectives on their use. For instance, they have been recently considered for introducing optical nonlinearity in photonic reservoir computing systems. In this work, we present a detailed numerical investigation of a silicon MRR operation, in the presence of external optical feedback, in a time delay reservoir computing scheme. We demonstrate the versatility of this compact, passive device, by exploiting different operating regimes and solving computing tasks with diverse memory requirements. We show that when large memory is required, as it occurs in the Narma 10 task, the MRR nonlinearity does not play a significant role when the photodetection nonlinearity is involved, while the contribution of the external feedback is significant. On the contrary, for computing tasks such as the Mackey-Glass and the Santa Fe chaotic timeseries prediction, the MRR and the photodetection nonlinearities contribute both to efficient computation. The presence of optical feedback improves the prediction of the Mackey-Glass timeseries while it plays a minor role in the Santa Fe timeseries case.
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- 2021
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46. A silicon source of heralded single photons at 2 $\mu$m
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Signorini, S., Sanna, M., Piccione, S., Ghulinyan, M., Tidemand-Lichtenberg, P., Pedersen, C., and Pavesi, L.
- Subjects
Quantum Physics ,Physics - Optics - Abstract
Mid infrared integrated quantum photonics is a promising platform for applications in sensing and metrology. However, there are only few examples of on-chip single photon sources at these wavelengths. These have limited performances with respect to their C-band counterparts. In this work, we demonstrate a new approach to generate heralded single photons in the mid infrared on a silicon chip. By using a standard C-band pump, the inter-modal spontaneous four wave mixing enables the generation of the herald idler at 1259.7 nm and the heralded signal at 2015 nm. The idler photon is easily detected with a common infrared single photon detector while the signal photon is upconverted to the visible before its detection. In this way, we are able to operate a mid infrared source without the need of mid infrared detectors and laser sources. By measuring a heralded $g^{(2)}$ of $0.23 \, \pm \, 0.08$ we demonstrate the single photon behaviour of the source as well as the feasibility of multi-photon coincidence measurements beyond 2 $\mu$m with our setup. The source exhibits a high intrinsic heralding efficiency of $(59 \, \pm \,5)\%$, a maximum coincidence to accidental ratio of $40.4 \, \pm \, 0.9$ and a generation probability of $\left( 0.72 \, \pm \, 0.10 \right)$ W$^{-2}$.
- Published
- 2021
- Full Text
- View/download PDF
47. Analysis of polyphenols, anthocyanins and toxic elements in Açaí Juice (Euterpe oleracea Mart.): Quantification and in vivo assessment of the antioxidant capacity of clarified Açaí juice
- Author
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da Costa, David Silva, Bragotto, Adriana Pavesi Arisseto, de Carvalho, Leandro Machado, Amado, Lílian Lund, Lima, Rafael Rodrigues, and Rogez, Hervé
- Published
- 2024
- Full Text
- View/download PDF
48. Impact of chitosan-incorporated toothpaste on roughness, gloss, and antifungal potential of acrylic resin
- Author
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Varaschin Theodorovicz, Kaye, Vieira-Junior, Waldemir Franscisco, Manoel Garcia, Raissa, Pini Simões Gobbi, Ludmila, Mayume Mori, Mariana, Prado Dias Filho, Benedito, Alves Nunes Leite Lima, Débora, Sundfeld, Daniel, and Pavesi Pini, Núbia Inocencya
- Published
- 2023
- Full Text
- View/download PDF
49. Data treatment methods for real-time colorimetric loop-mediated isothermal amplification reactions
- Author
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Kim, Edson Yu Sin, Imamura, Louise Matiê, Winkert Raddatz, Bruna, Timm Soares, Santiago Pedro, Alves Ribeiro, Victor Henrique, Rinaldi Pavesi Nicollete, Diego, Bergamo Santiago, Erika, Mazega Figueredo, Marcus Vinícius, Montesanti Machado de Almeida, Bernardo, and Renato Rogal, Jr, Sergio
- Published
- 2023
- Full Text
- View/download PDF
50. Human PNPase causes RNA stabilization and accumulation of R-loops in the Escherichia coli model system
- Author
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Falchi, Federica A., Forti, Francesca, Carnelli, Cristina, Genco, Aurelia, Pizzoccheri, Roberto, Manzari, Caterina, Pavesi, Giulio, and Briani, Federica
- Published
- 2023
- Full Text
- View/download PDF
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