Engineering Transport via Collisional Noise: a Toolbox for Biology Systems

The study of noise assisted transport in quantum systems is essential in a wide range of applications from near-term NISQ devices to models for quantum biology. Here, we study a generalised XXZ model in the presence of stochastic collision noise, which allows to describe environments beyond the standard Markovian formulation. Our analysis through the study of the local magnetization, the inverse participation ratio (IPR) or its generalisation, the Inverse Ergodicity Ratio (IER), showed clear regimes where the transport rate and coherence time can be controlled by the dissipation in a consistent manner. In addition, when considering several excitations, we characterize the interplay between collisions and system interactions identifying regimes in which transport is counterintuitively enhanced when increasing the collision rate, even in the case of initially separated excitations. These results constitute an example of the essential building blocks for the understanding of quantum transport in structured noisy and warm disordered environments.Comment: 18 pages, 6 figure

The Italian National External Quality Assessment Program in Cytogenetics: 4 years of activity (2013-2016) following the introduction of poor performance criteria

Background. Italian External Quality Assessment (IEQA) Program in Cytogenetics, established in 2001 by the Istituto Superiore di Sanità (ISS), covers both Constitutional and Oncohaematological diagnosis. In 2013, performance criteria were defined and adopted. In this paper, we present the data from the first 4 years of activity (2013-2016) following the introduction of performance criteria. Methods. The enrollment is voluntary, fee-based and open to both public and private Italian laboratories. The scheme is annual and retrospective; a national panel of experts assess technical, analytical and interpretative performance. Results. Overall, 95 distinct Italian laboratories participated in different Cytogenetics IEQA schemes over the 2013-2016 years and most of the laboratories took part in Constitutional diagnosis. General hospitals and local health centers represented 40% of the total participants and the percentage of laboratories from Northern Regions was more than 45% of total participants throughout the 4-year period. As regards the performance evaluation, on average, 11, 9 and 23% of participants were marked as poor performers in Prenatal, Postnatal and Oncohaematological schemes, respectively. With regard to critical errors, ISCN nomenclature in Prenatal and Postnatal schemes, and interpretation in Oncohaematological diagnosis, were identified as main issues. On the other hand, karyotype errors and inadequate analysis decreased strongly, over the 4 years, in Constitutional and Oncohaematological diagnosis, respectively. Conclusions. Our data show that the introduction of poor performance encourages laboratories to address critical issues, and the IEQA participation helps to improve quality in cytogenetic testing. 

Noise Engineering of Quantum Transport through Stochastic Collision Models

As quantum technologies and condensed matter physics advance, the study of open quantum systems becomes increasingly necessary beyond the fact that any actual, measurable system in the laboratory cannot be perfectly isolated. In fact, under certain conditions the presence of interaction with the environment can lead to the occurrence of interesting physical phenomena, not observable in closed systems. Current technological developments of quantum systems, including their tailored coupling to their environment, create new paradigms where dissipative engineering represents a new way in which we can program and control quantum matter. The main consequence of considering the interaction between the system we are interested in, and the environment around it, is the manifestation of effects such as decoherence and dissipation. Quantum decoherence describes the loss of coherence of a quantum state and constitutes an essential concept in quantum information. Dissipation, on the other hand, is the common effect in an open system characterized by the loss of energy into the environment, which can include the loss of particles. These features of open systems have been exploited to discover new quantum regimes, via e.g. the cooling of the system, or dissipative state preparation, and also explore the emergence of new phases of matter. The use of this new physics requires, however, an understanding and modeling of the interaction between system and environment. This description is generally very complicated because of the large number of degrees of freedom of the environment itself. In this regard, approximations are often used to describe the environment, also called bath, in simpler terms. One of the descriptions of open systems in vogue in recent years is provided by quantum collision models, also denoted as repeated interaction schemes. In this description, the bath is modeled as a set of small subunits called ancillas, that interact one at a time with the system or a part of it. These interactions are assumed to be pairwise and instantaneous. This simplified discretization of the bath allows to drastically simplify the problem: this is why such models are increasingly involved in the study of quantum non-Markovian dynamics, quantum optics, and quantum thermodynamics. While these models are applied to a wide range of systems, in this thesis we will be focusing on Markovian dynamics, which implies the absence of memory effects. In particular, we want to study the transport properties of noisy media with links to biology, delocalization aspects in quantum complex networks and to quantum transport in 1D-lattices. We also analyse how transport can be favored or inhibited by acting both on the environment and the interactions inside the system. For this work, we consider a specific sub-branch of collision models, that are the stochastic collision models. In this specific formulation, the collisions are governed by a stochastic process and the unraveling of the system’s evolution can be described in terms of individual random realizations. Thus, an important role is played by the specific stochastic process that we have chosen to describe the time lapsed between two collisions. As our aim is to consider the most general noise distribution, we resort to the concept of Weibull process. In fact, the Weibull distribution allows to explore a variety of bath-induced noise regimes, by tailoring both the number of collisions occurring over time and their space and time homogeneity. We perform a systematic study by simulating a number of realizations, each sampled from the distribution leading to a particular collision configuration, and average over them to obtain the effective evolution of our system. As a prototype for our analysis, we choose an anisotropic quantum spin chain, a paradigmatic system also known as the Heisenberg XXZ model. We work at fixed magnetization, which allows us to reduce the computational complexity of the problem as the magnetization is preserved in the anisotropic Heisenberg model. We first carry out a thorough analysis of the convergence of our numerical method. Then, we move on to the study of transport and delocalization. In order to do so, we first focus on the evolution of a spin chain with one single spin impurity (excitation) and analyse the relevant observables over time. We study the magnetization and how the excitation spreads over the chain, also considering the inverse participation ratio (IPR) which is a quantitative measure of localization for an excitation, often used in quantum networks. We then address the role of noise in stochastic collision models in the presence of interactions, that in our model appear in the form of anisotropy. To do so, we need to increase the number of excitations. We thus switch to two of them and introduce the inverse ergodicity ratio (IER), which - contrary to IPR - allows us to quantify ergodicity and localization in the system case of more than one excitation. Our studies reveal that noise can be engineered to control the system transport properties. While normal structure-less noise leads to transport slowdown, we find specific regimes where we can minimize this effect, tailor the amount of coherent oscillations of the dynamics, or even enhance transport in the case where the particles are pinned together due to their interaction. This suggests that further scenarios can be found, where other competing mechanisms preventing transport, like it occurs in disordered systems or randomly connected networks, can be overcome by the engineering of collision models. We believe our study constitutes one of first step in building this understanding

Engineering Transport via Collisional Noise: A Toolbox for Biology Systems

The study of noise assisted-transport in quantum systems is essential in a wide range of applications, from near-term NISQ devices to models for quantum biology. Here, we study a generalized XXZ model in the presence of stochastic collision noise, which allows describing environments beyond the standard Markovian formulation. Our analysis through the study of the local magnetization, the inverse participation ratio (IPR) or its generalization, and the inverse ergodicity ratio (IER) showed clear regimes, where the transport rate and coherence time could be controlled by the dissipation in a consistent manner. In addition, when considering various excitations, we characterized the interplay between collisions and system interactions, identifying regimes in which transport was counterintuitively enhanced when increasing the collision rate, even in the case of initially separated excitations. These results constitute an example of an essential building block for the understanding of quantum transport in structured noisy and warm-disordered environments

Sottoprodotti agroalimentari ed economia circolare: una sinergia efficiente? L’esempio del progetto BIOFACE

Il progetto BIOFACE, acronimo del progetto intitolato “Biomolecole dalla valorizzazione integrata di sottoprodotti agroalimentari per applicazioni sostenibili con finalit  Fitosanitarie, alimentari, ed energetiche” - Programma di Sviluppo Rurale PSR 2014-2020 Op. 16.1.01 - GO PEI-Agri - FA 5C dell’Emilia RomagnaUn importante e interessante esempio di come l’economia circolare, che tende a valorizzare i sottoprodotti della filiera agroalimentare, possa realizzarsi con un progetto che coinvolge e unisce in maniera trasversale le forze e le competenze delle industrie, delle istituzioni e dell’Università

Positive predictive values and outcomes for uninformative cell-free DNA tests: An Italian multicentric Cytogenetic and cytogenomic Audit of diagnOstic testing (ICARO Study)

Objectives: To establish the positive predictive values (PPV) of cfDNA testing based on data from a nationwide survey of independent clinical cytogenetics laboratories. Methods: Prenatal diagnostic test results obtained by Italian laboratories between 2013 and March 2020 were compiled for women with positive non-invasive prenatal tests (NIPT), without an NIPT result, and cases where there was sex discordancy between the NIPT and ultrasound. PPV and other summary data were reviewed. Results: Diagnostic test results were collected for 1327 women with a positive NIPT. The highest PPVs were for Trisomy (T) 21 (624/671, 93%) and XYY (26/27, 96.3%), while rare autosomal trisomies (9/47, 19.1%) and recurrent microdeletions (8/55, 14.5%) had the lowest PPVs. PPVs for T21, T18, and T13 were significantly higher when diagnostic confirmation was carried out on chorionic villi (97.5%) compared to amniotic fluid (89.5%) (p < 0.001). In 19/139 (13.9%), of no result cases, a cytogenetic abnormality was detected. Follow-up genetic testing provided explanations for 3/6 cases with a fetal sex discordancy between NIPT and ultrasound. Conclusions: NIPT PPVs differ across the conditions screened and the tissues studied in diagnostic testing. This variability, issues associated with fetal sex discordancy, and no results, illustrate the importance of pre- and post-test counselling