Quantum Phase-Slip Junction Under Microwave Irradiation

We consider the dynamics of a quantum phase-slip junction (QPSJ) -- a dual Josephson junction -- connected to a microwave source with frequency $\omega_\textrm{mw}$. With respect to an ordinary Josephson junction, a QPSJ can sustain dual Shapiro steps, consisting of well-defined current plateaus at multiple integers of $e \omega_\textrm{mw} / \pi$ in the current-voltage (I-V) characteristic. The experimental observation of these plateaus has been elusive up to now. We argue that thermal as well as quantum fluctuations can smear the I-V characteristic considerably. In order to understand these effects, we study a current-biased QPSJ under microwave irradiation and connected to an inductive and resistive environment. We find that the effect of these fluctuations are governed by the resistance of the environment and by the ratio of the phase-slip energy and the inductive energy. Our results are of interest for experiments aimed at the observation of dual Shapiro steps in QPSJ devices for the definition of a new quantum current standard.Comment: 12 pages, 9 figures, comments and suggestions would be greatly appreciate

Thermoelectrics of Interacting Nanosystems -- Exploiting Superselection instead of Time-Reversal Symmetry

Thermoelectric transport is traditionally analyzed using relations imposed by time-reversal symmetry, ranging from Onsager's results to fluctuation relations in counting statistics. In this paper, we show that a recently discovered duality relation for fermionic systems -- deriving from the fundamental fermion-parity superselection principle of quantum many-particle systems -- provides new insights into thermoelectric transport. Using a master equation, we analyze the stationary charge and heat currents through a weakly coupled, but strongly interacting single-level quantum dot subject to electrical and thermal bias. In linear transport, the fermion-parity duality shows that features of thermoelectric response coefficients are actually dominated by the average and fluctuations of the charge in a dual quantum dot system, governed by attractive instead of repulsive electron-electron interaction. In the nonlinear regime, the duality furthermore relates most transport coefficients to much better understood equilibrium quantities. Finally, we naturally identify the fermion-parity as the part of the Coulomb interaction relevant for both the linear and nonlinear Fourier heat. Altogether, our findings hence reveal that next to time-reversal, the duality imposes equally important symmetry restrictions on thermoelectric transport. As such, it is also expected to simplify computations and clarify the physical understanding for more complex systems than the simplest relevant interacting nanostructure model studied here.Comment: 38 pages (23 main paper, 15 appendix), 8 figure

Topological Constraints in Eukaryotic Genomes and How They Can Be Exploited to Improve Spatial Models of Chromosomes

Several orders of magnitude typically separate the contour length of eukaryotic chromosomes and the size of the nucleus where they are confined. The ensuing topological constraints can slow down the relaxation dynamics of genomic filaments to the point that mammalian chromosomes are never in equilibrium over a cell's lifetime. In this opinion article, we revisit these out-of-equilibrium effects and discuss how their inclusion in physical models can enhance the spatial reconstructions of interphase eukaryotic genomes from phenomenological constraints collected during interphase.Comment: 5 pages, 1 figure, opinion article, submitted for publicatio

Controllo ottimale quantistico di qubits superconduttivi di carica

E' stato studiato il sistema composto da due qubits interagenti costituito da due Cooper-pair boxes (qubits superconduttivi di carica) connessi tramite una giunzione Josephson. Si è controllato in modo ottimale il primo qubit per poter realizzare il NOT logico sia sul primo che sul secondo. Il calcolo degli impulsi usati per il controllo ottimale del sistema è stato effettuato attraverso due algoritmi numerici: quello di Krotov e il CRAB (Chopped RAndom Basis), entrambi codificati in linguaggio FORTRAN. Sono stati quindi analizzati l'andamento degli errori legati alla corretta realizzazione del NOT logico e soprattutto la forma e lo spettro dei segnali ottenuti attraverso i due algoritmi

The boundary flux. New perspectives for membrane process design

In the last decades much effort was put in understanding fouling phenomena on membranes. Many new concepts have been introduced in time, and parallel to this many parameters capable to quantify fouling issues and fouling evolution. One successful approach was the introduction of the critical flux theory. At first validated for microfiltration, the theory applied to ultrafiltration and nanofiltration, too. The possibility to measure a maximum value of the permeate flux for a given system without incurring in fouling issues was a breakthrough in membrane process design. Nevertheless, the application to the concept remains very limited: in many cases, in particular on systems where fouling is a main issue, critical fluxes were found to be very low, lower than economical feasibility permits to make membrane technology advantageous. Despite these arguments, the knowledge of the critical flux value still remains and must be considered as a good starting point for process design concerning productivity and longevity. In 2011, a new concept was introduced, that is the threshold flux. In this case, the concept evaluates the maximum permeate flow rate characterized by a low constant rate fouling regime, due to formation of a secondary, selective layer of foulant on the membrane surface. This concept, more than the critical flux, may be a new practical tool for membrane process designers. In this paper a brief review on critical and threshold flux will be reported and analyzed. In fact, critical and threshold flux concepts share many common aspects which merge perfectly into a new concept that is the boundary flux. The validation will occur mainly by the analysis of previous collected data by the authors, during the treatment of olive mill wastewater. A novel membrane process design method based on the boundary flux will then be presented

Superconducting cascade electron refrigerator

The design and operation of an electronic cooler based on a combination of superconducting tunnel junctions is described. The cascade extraction of hot-quasiparticles, which stems from the energy gaps of two different superconductors, allows for a normal metal to be cooled down to about 100 mK starting from a bath temperature of 0.5 K. We discuss the practical implementation, potential performance and limitations of such a device

Obesity, Male Reproductive Function and Bariatric Surgery

Overweight and obesity are associated with several chronic complications, such as type 2 diabetes, arterial hypertension and atherosclerotic cardiovascular diseases, with relevant consequences for patients and public health systems. Reproductive function abnormalities, such as obesity-related secondary hypogonadism, erectile dysfunction and infertility, represent other abnormalities negatively affecting the quality of life of men suffering from obesity but, despite their high prevalence, these are often understated because of a general lack of awareness in clinical practice. Obesity and gonadal function are closely related, with obesity being associated with hypogonadism that is reversed by body weight reduction thus ameliorating reproductive and sexual health. Clinical studies specifically evaluating the impact of non-surgical weight loss on testosterone levels sometimes showed conflicting results, whereas extensive literature has demonstrated that weight loss after bariatric surgery is correlated with an increase in testosterone levels greater than that obtained with only lifestyle interventions, suggesting the role of surgery also for the treatment of hypogonadism in obese male. However, studies concerning the consequences of bariatric surgery on overall reproductive function in the male, including also sexual activity and fertility, are limited and data regarding long-term effects are lacking. Here we present a brief review summarizing the evidence regarding the interplay between obesity and reproductive abnormalities in the obese male, together with the role of bariatric surgery for the treatment of these complications, describing both the positive effects and the limitations of this procedure

Relationship between Heart Disease and Liver Disease: A Two-Way Street

In clinical practice, combined heart and liver dysfunctions coexist in the setting of the main heart and liver diseases because of complex cardiohepatic interactions. It is becoming increasingly crucial to identify these interactions between heart and liver in order to ensure an effective management of patients with heart or liver disease to provide an improvement in overall prognosis and therapy. In this review, we aim to summarize the cross-talk between heart and liver in the setting of the main pathologic conditions affecting these organs. Accordingly, we present the clinical manifestation, biochemical profiles, and histological findings of cardiogenic ischemic hepatitis and congestive hepatopathy due to acute and chronic heart failure, respectively. In addition, we discuss the main features of cardiac dysfunction in the setting of liver cirrhosis, nonalcoholic fatty liver disease, and those following liver transplantation

Perspectives in nanotechnology based innovative applications for the environment

In this perspective paper, the actual trends in nanotechnology based innovative applications for the environment are analyzed and possible future trends were studied. On the basis of the relevant topics of the NINE congress held in Rome, 2016, a bibliographical search was performed on papers fitting in one or more categories within the last 5 years, that is: 1. Nanosensors and bionanosensors for environmental characterization and monitoring 2. Technologies for the production of Nanomaterials for the environment 3. Nanostructured materials for advanced remediation processes 4. Nano-based water and wastewater treatment processes 5. Membrane processes for the environment 6. Health and safety issues concerning Nanomaterials 7. Education on Environmental Engineering and Nanotechnology. A yearly count of contributions was performed and taken as an indicator of interest of the specific topic within the wide broad scientific community. In a second step, the resulting data was analyzed by regression techniques to estimate the trend in the next future and to evaluate the next challenges within the international research framework

Autonomic Faulty Node Replacement in UAV-Assisted Wireless Sensor Networks: a Test-bed

Several use-cases of the Internet of Things (IoT) rely on the development of large-scale Wireless Sensor Networks (WSNs) in harsh environments characterized by limited Internet connectivity and battery-powered operations. In such scenarios, the failure of a single node due to energy depletion or hardware issues may cause network partitions and disrupt partially or completely the system operations until the intervention of a human operator. In this paper, we investigate the usage of Unmanned Aerial Networks (UAVs) to enable sensory data collection and support resilient communications in presence of faulty sensor nodes. More specifically, we study the possibility of replacing the ground devices with UAVs which are able to temporarily restore the multi-hop communication towards the WSN sink. To this aim, we extended the Uhura framework, a platform for robotic networking, with novel features for automatic network partition detection and UAV-sink coordination. Then, we created a small test-bed composed of a Bluetooth Mesh WSN and one drone, and characterized the performance of the UAV-assisted WSN system in terms of packet delivery ratio of the end-to-end data flows