Coherent excitation transport through ring-shaped networks

The coherent quantum transport of matter wave through a ring-shaped circuit attached to leads defines an iconic system in mesoscopic physics that has allowed both to explore fundamental questions in quantum science and to draw important avenues for conceiving devices of practical use. Here we study the source-to-drain transport of excitations going through a ring-network, without propagation of matter waves. We model the circuit in terms of a spin system with specific long-range interactions that are relevant for quantum technology, such as Rydberg atoms trapped in optical tweezers or ion traps. Inspired by the logic of rf- and dc-SQUIDs, we consider rings with one and two local energy offsets, or detunings. As a combination of specific phase shifts in going though the localized detunings and as a result of coherent tunneling, we demonstrate how the transport of excitations can be controlled, with a distinctive dependence on the range of interactions.Comment: Main text: 9 pages, 4 figures. Appendix: 16 pages, 10 figure

Controlled flow of excitations in a ring-shaped network of Rydberg atoms

Highly excited Rydberg atoms are a powerful platform for quantum simulation and information processing. Here, we propose atomic ring networks to study chiral currents of Rydberg excitations. The currents are controlled by a phase pattern imprinted via a Raman scheme and can persist even in the presence of dephasing. Depending on the interplay between the Rabi coupling of Rydberg states and the dipole-dipole atom interaction, the current shows markedly different features. The excitations propagate with a velocity displaying a characteristic peak in time, reflecting the chiral nature of the current. We find that the time-averaged current in a quench behaves similarly to the ground-state current. This analysis paves the way for the development of new methods to transport information in atomic networks.Comment: 6 pages main, 6 figures + appendice

Perspective on new implementations of atomtronic circuits

In this article, we provide perspectives for atomtronics circuits on quantum technology platforms beyond simple bosonic or fermionic cold atom matter-wave currents. Specifically, we consider (i) matter-wave schemes with multi-component quantum fluids; (ii) networks of Rydberg atoms that provide a radically new concept of atomtronics circuits in which the flow, rather than in terms of matter, occurs through excitations; (iii) hybrid matter-wave circuits - cavities systems that can be used to study atomtronic circuits beyond the standard solutions and provide new schemes for integrated matter-wave networks. We also sketch how driving these systems can open new pathways for atomtronics

A Citrus bergamia

The aim of this research was to assess the impact of a well-characterized extract from Citrus bergamia juice on adipogenesis and/or lipolysis using mesenchymal stem cells from human adipose tissue as a cell model. To evaluate the effects on adipogenesis, some cell cultures were treated with adipogenic medium plus 10 or 100 μg/mL of extract. To determine the properties on lipolysis, additional mesenchymal stem cells were cultured with adipogenic medium for 14 days and after this time added with Citrus bergamia for further 14 days. To verify adipogenic differentiation, oil red O staining at 7, 14, 21, and 28 days was performed. Moreover, the expression of peroxisome proliferator-activated receptor gamma (PPAR-γ), adipocytes fatty acid-binding protein (A-FABP), adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), monoglyceride lipase (MGL), 5′-adenosine monophosphate-activated protein kinase (AMPK)α1/2, and pAMPKα1/2 was evaluated by Western blot analysis and the release of glycerol by colorimetric assay. Citrus bergamia extract suppressed the accumulation of intracellular lipids in mesenchymal stem cells during adipogenic differentiation and promoted lipolysis by repressing the expression of adipogenic genes and activating lipolytic genes. Citrus bergamia extract could be a useful natural product for improving adipose mobilization in obesity-related disorders

Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018.

Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field

Multipartite entanglement in many-body localized quantum systems

According to quantum mechanics it is possible to prepare states that describe the global system but they do not provide information on its subparts, it is a typical feature of non-classical systems related to quantum correlations. A state that describes the global system but does not describe its subparts is called entangled. Bipartite entanglement is quantified by the von Neumann entropy and it has been used in the context of quantum information and more, in fact it plays a central role also in the field quantum phase transitions (QPTs) theory. For instance, in ground-state QPTs it has been observed that entanglement permits to differentiate critical and non-critical behaviour of the system. On the other hand, the concept of multipartite entanglement in the field of many-body physics has not been much investigated yet, anyway there exist some works in which it has been analyzed in QPTs. It has been shown that the multipartite entanglement may be a useful device to differentiate the various phases of the system. Multipartite entanglement may be studied through the quantum Fisher information (QFI) which does not permit to obtain a quantitative estimate, but it enables to differentiate between different types of it. This thesis work wants to be in continuity with the idea to study QPTs by using multipartite entanglement, we will work with a particular phase transition that is not a ground-state phase transition but it involves all the states of the energy spectrum. The phenomenon we are talking about is the many-body localization (MBL), that is a finite-temperature phase transition of a quantum system from an ergodic phase to a localized one. The models with which we work describe interacting fermions subject to a disordered external field in 1D; we generate disorder in two different ways: the first way is to build up an external random on-site potential, the second one is to use a quasi-periodic potential. It is observed that for strong disorder the eigenstate thermalization hypothesis (ETH), which is in few words the quantum generalization of classical ergodic hypothesis, fails; in a many-body localized phase the system does not thermalize and so it maintains information of its initial conditions during its evolution. Quantitatively, the quantum thermalization is studied using random matrix theory; if the system does thermalize the level spacing statistics of the Hamiltonian follows a given distribution of the Wigner-Dyson type, which is called `Gaussian orthogonal ensemble', in contrast, if the system does not thermalize, the Hamiltonian level spacing statistics follows a distribution which is Poissonian. Another important feature of MBL is the non-thermal behaviour of entanglement entropy (the von Neumann entropy of a partition of the system that quantifies bipartite entanglement). In particular, it is observed that in the ergodic phase the entropy has an extensive (thermal) behaviour by the fact that the system does thermalize; in the localized phase the system does not thermalize and so the entanglement entropy has an intensive behaviour. Phenomenologically, MBL is tested on cold-atom platforms, after a long time evolution, it is observed as for weak disorder the system erases any information of its initial conditions due to thermalization, for strong disorder the system maintains memory of initial conditions. Therefore, the original part of this thesis is a numerical study of this type of phase transition using the QFI. The numerical approach is necessary because the insertion of disorder makes the system not tractable analytically, in particular, the complexity of the problem is due to the concomitant presence of interactions and disorder. The MBL is a transition that manifests itself on Hamiltonian's excited states and for this the numerical tool used is the exact diagonalization; once the Hamiltonian is diagonalized, we can evaluate the QFI by the computation of various correlation functions and so we have information on multipartite entanglement. We study the QFI using the standard procedure described in fixing Hamiltonian's eigenstates on which to perform the computation and varying the disorder (and vice versa). By a comparison with entanglement entropy we show that this computation is incomplete, in particular it emerges that there are some states that are bipartite entangled according to the entropy computation but they are not entangled according to our QFI computation. The above computation is made complete by taking into account anisotropies that are contained in models as those considered. We show that when disorder is absent the behaviour of entanglement in the spectrum is strongly irregular, there are states that do not seem to show any form of entanglement, others that show at least bipartite entanglement and others that show entanglement more than bipartite (multipartite). What emerges is that at the edges of the spectrum the entanglement is typically bigger than at the center of the spectrum in the sense that more spins tend to correlate with each other. When the disorder is switched on, in the ergodic phase, we observe as at the center of the spectrum at least bipartite entanglement emerges, while at the edges of the spectrum states does show at least 3-partite entanglement. When the disorder exceeds a certain critical value that depends on the model with which we work, the system becomes localized; in terms of entanglement what we observe is that any form of entanglement tends to disappear. Physically, the observations in the ergodic phase are related to the fact that in this phase the system does thermalize, so its entanglement entropy is extensive and the amount of bipartite entanglement is highly non negligible anywhere in the energy spectrum excluding edges. Instead, in the localized phase, information does not spread along the chain, the system does not reach equilibrium and maintains memory of its initial conditions. In some sense, it describes a situations as if spins do not talk each other and so any form of correlation between them is absent. This thesis work represents a starting point for the study of disordered quantum systems using QFI and so multipartite entanglement. In the future, we can think to extend our analysis to other models that show MBL or, in general, to characterize new phases of matter not necessarily at zero temperature and to shed light on phases of which little is yet known

Effects of General Fatigue Induced by Exhaustive Exercise on Posture and Gait Stability of Healthy Young Men

Bipedal walking is a composite task requiring integration of many control circuitries in the brain and spinal cord. The present study was carried out to verify whether an increase in blood lactate, such as that associated with a high intensity exercise, is able to significantly modify the qualitative and/or quantitative aspects of human walking. Eighteen healthy physically male participants, aged between 20 and 24 years (M = 21.8, SD = 1.22), were recruited for the study. For this purpose, the experimental protocol included the measure of blood lactate levels with the aim of assessing possible relations between lactate blood values and different aspect of walking after an exhaustive exercise. An exhaustive exercise was associated with a strong increase of blood lactate levels and produced a significant worsening in the ability to maintain the bipodalic upright posture as well as the fluidity of walking. Our results suggest that exhausting bouts impose greater challenges on postural control

Effects of mild aerobic exercise training on the diaphragm in mdx mice

Mild endurance exercise training positively affects limb skeletal muscle in the mdx mice model of Duchenne Muscular Dystrophy (DMD). However, few and controversial data are available on the effects of mild exercise training on the diaphragm of mdx mice. The diaphragm was examined in mdx and wild type mice either under sedentary conditions (mdx-SD, WT-SD) or during mild exercise training (mdx-EX, WT-EX). At baseline and after 30 and 45 days of training (5 d/wk for 6 weeks), diaphragm muscle morphology and Cx39 protein were assessed. In addition, tissue levels of the chaperonin Hsp60 were measured at the same time points in gastrocnemius, quadriceps and diaphragm in each experimental group. Although morphological analysis showed unchanged total area of necrosis/regeneration in the diaphragm after training, there was a trend for regeneration areas to be larger than necrosis areas. However, the levels of Cx39 protein, a marker associated with active degeneration-regeneration process in damaged muscle were similar in the diaphragm of mdx-EX and mdx-SD mice. The diaphragm, but not limb muscles, of both trained and sedentary mdx mice showed decreased Hsp60 expression at 45 days, suggesting exhaustion of potentially protective mechanisms in the diaphragm similar to previous findings in lung epithelium. Compared to the positive effects of exercise training previously observed in limb skeletal muscles, the diaphragm showed little change after training

Photoplethysmographic Prediction of the Ankle-Brachial Pressure Index through a Machine Learning Approach

Cardiovascular disease is a leading cause of death. Several markers have been proposed to predict cardiovascular morbidity. The ankle-brachial index (ABI) marker is defined as the ratio between the ankle and the arm systolic blood pressures, and it is generally assessed through sphygmomanometers. An alternative tool for cardiovascular status assessment is Photoplethysmography (PPG). PPG is a non-invasive optical technique that measures volumetric blood changes induced by pulse pressure propagation within arteries. However, PPG does not provide absolute pressure estimation, making assessment of cardiovascular status less direct. The capability of a multivariate data-driven approach to predict ABI from peculiar PPG features was investigated here. ABI was measured using a commercial instrument (Enverdis Vascular Explorer, VE-ABI), and it was then used for a General Linear Model estimation of ABI from multi-site PPG in a supervised learning framework (PPG-ABI). A Receiver Operating Characteristic (ROC) analysis allowed to investigate the capability of PPG-ABI to discriminate cardiovascular impairment as defined by VE-ABI. Findings suggested that ABI can be estimated form PPG (r = 0.79) and can identify pathological cardiovascular status (AUC = 0.85). The advantages of PPG are simplicity, speed and operator-independency, allowing extensive screening of cardiovascular status and associated cardiovascular risks