A brief journey through collision models for multipartite open quantum dynamics

The quantum collision models are a useful method to describe the dynamics of an open quantum system by means of repeated interactions between the system and some particles of the environment, which are usually termed "ancillas". In this paper, we review the main collision models for the dynamics of multipartite open quantum systems, which are composed of several subsystems. In particular, we are interested in models that are based on elementary collisions between the subsystems and the ancillas, and that simulate global and/or local Markovian master equations in the limit of infinitesimal timestep. After discussing the mathematical details of the derivation of a generic collision-based master equation, we provide the general ideas at the basis of the collision models for multipartite systems, we discuss their strengths and limitations, and we show how they may be simulated on a quantum computer. Moreover, we analyze some properties of a collision model based on entangled ancillas, derive the master equation it generates for small timesteps, and prove that the coefficients of this master equation are subject to a constraint that limits their generality. Finally, we present an example of this collision model with two bosonic ancillas entangled in a two-mode squeezed thermal state.Comment: Submitted to a special issue of Open Syst. Inf. Dyn. devoted to the memory of Prof. A. Kossakowski. Comments and suggestions are welcom

Bath-Induced Collective Phenomena on Superconducting Qubits : Synchronization, Subradiance, and Entanglement Generation

A common environment acting on a pair of qubits gives rise to a plethora of different phenomena, such as the generation of qubit-qubit entanglement, quantum synchronization, and subradiance. Here, time-independent figures of merit for entanglement generation, quantum synchronization, and subradiance are defined, and an extensive analytical and numerical study of their dependence on model parameters is performed. A recently proposed measure of the collectiveness of the dynamics driven by the bath is also addressed, and it is found that it almost perfectly witnesses the behavior of entanglement generation. The results show that synchronization and subradiance can be employed as reliable local signatures of an entangling common-bath in a general scenario. Finally, an experimental implementation of the model based on two transmon qubits capacitively coupled to a common resistor is proposed, which provides a versatile quantum simulation platform of the open system in any regime.Peer reviewe

Soothing and anti-itch effect of quercetin phytosome in human subjects: A single-blind study

Background: We evaluated the ability of quercetin, a natural antioxidant formulated in a specific delivery system, to reduce skin inflammation induced by a variety of stimuli, including UV radiation, stimulation with a histamine solution, or contact with chemical irritants. In particular, we tested the soothing and anti-itch effect of Quercevita\uc2\uae, 1% cream for external use, a formulation characterized by a phospholipids-based delivery system. Patients and methods: The study was a monocentric, single blind trial that enrolled a group of 30 healthy volunteers. The back of each subject was examined to identify four quadrants with no previous skin damage or naevi that were treated in order to induce a controlled and reversible form of skin stress. The areas were treated as follows: no product; Quercevita\uc2\uae 1% cream, 2 mg/cm2; placebo; positive control (a commercially available topical formulation containing 1% dexchlorpheniramine). Results: Only quercetin phospholipids 1% and dexchlorpheniramine 1% achieved a significant reduction in erythema with comparable results: (\ue2\u80\u9310.05% [P=0.00329] for quercetin phospholipids 1% vs \ue2\u80\u9314.05% [P=0.00046] for the positive control). Moreover, quercetin phospholipids 1% and dexchlorpheniramine 1% were both associated with a significant decrease in mean wheal diameter: (\ue2\u80\u9313.25% and \ue2\u80\u9312.23% for dexchlorpheniramine 1%, respectively). Similar findings were reported for the other tested parameters. Conclusion: Quercetin has a skin protective effect against damage caused by a variety of insults, including UV radiation, histamine, or contact with toxic chemical compounds. Indeed, quercetin is able to reduce redness, itching, and inflammation of damaged skin; it may also help restore skin barrier function, increasing hydration, and reducing water loss

Depression, obesity and their comorbidity during pregnancy : effects on the offspring's mental and physical health

Depression and obesity represent two of the most common complications during pregnancy and are associated with severe health risks for both the mother and the child. Although several studies have analysed the individual effects of depression or obesity on the mothers and their children, the effects associated with the co-occurrence of both disorders have so far been poorly investigated. The relationship between depression and obesity is very complex and it is still unclear whether maternal depression leads to obesity or vice versa. It is well known that the intrauterine environment plays an important role in mediating the effects of both depression and obesity in the mother on the fetal programming, increasing the child's risk to develop negative outcomes.Peer reviewe

Local versus global master equation with common and separate baths: superiority of the global approach in partial secular approximation

Open systems of coupled qubits are ubiquitous in quantum physics. Finding a suitable master equation to describe their dynamics is therefore a crucial task that must be addressed with utmost attention. In the recent past, many efforts have been made toward the possibility of employing local master equations, which compute the interaction with the environment neglecting the direct coupling between the qubits, and for this reason may be easier to solve. Here, we provide a detailed derivation of the Markovian master equation for two coupled qubits interacting with common and separate baths, considering pure dephasing as well as dissipation. Then, we explore the differences between the local and global master equation, showing that they intrinsically depend on the way we apply the secular approximation. Our results prove that the global approach with partial secular approximation always provides the most accurate choice for the master equation when Born?Markov approximations hold, even for small inter-system coupling constants. Using different master equations we compute the stationary heat current between two separate baths, the entanglement dynamics generated by a common bath, and the emergence of spontaneous synchronization, showing the importance of the accurate choice of approach

BDNF Val66Met polymorphism and protein levels in Amniotic Fluid

Brain-Derived Neurotrophic Factor (BDNF) is a neurotrophin which plays survival- and growth-promoting activity in neuronal cells and it is involved in cellular plasticity mechanisms as it controls activity dependent synaptic transmission. A functional polymorphism (Val66Met) in the pro-region of BDNF, which affects the intracellular trafficking of proBDNF has been associated with memory and cognitive deficits as well as to an increased susceptibility for several psychiatric disorders especially those with a neurodevelopmental origin. To date, no study has evaluated the influence of the Val66Met polymorphism on BDNF levels in a peripheral system that may reflect fetal neurodevelopment. Therefore we investigated in amniotic fluids (AF) obtained from 139 healthy women during 15-17 week of pregnancy, BDNF protein levels in correlation with the Val66Met polymorphism

In Vitro Antioxidant Potential of Baccharis trimera and Baccharis articulata Infusions in Postmenopausal Women

Considering that postmenopausal women generally have high levels of oxidative markers and low levels of antioxidant defense markers due to the reduction of estrogen levels, and because of the vast popular use of several species of carja in the form of infusion, this study aimed to evaluate in vitro if infusions of B. trimera and B. articulata have antioxidant potential in erythrocytes of postmenopausal women and which are the most effective. The erythrocytes from 40 postmenopausal women were treated in vitro for 1 hour with infusions of B. trimera and B. articulata at the following concentrations: 4, 8, 16, 33, 66 g/L. The negative control consisted of erythrocytes from postmenopausal women without treatment with the plants. After treatment, the levels of thiobarbituric acid reactive substances (TBARS), carbonylated proteins (CP), and reduced glutathione (GSH) were measured. The infusions of B. trimera and B. articulata at concentrations of 33 (p<0.001) and 66 g/L (p<0.001) reduced the level of TBARS in comparison to the negative control, and the effect size (ES) for this reduction was small. The levels of GSH increased after treating with B. trimera infusion at a concentration of 66 (p<0.001) and with B. articulata at concentrations of 33 (p<0.001) and 66 g/L (p<0.001), when compared with the negative control, and the ES for this increase was average. The infusions of B. trimera and B. articulata show antioxidant potential in vitro, thus showing a similar effect with regards to the reduction of oxidative damage to lipids and increased endogenous antioxidant protection

Comparison between hospitalized patients affected or not by COVID-19 (RESILIENCY study)

Dear Editor, in the recent report of Munblit and coworkers [1], authors observed that the combination of clinical features was sufficient to diagnose COVID-19 indicating that laboratory testing is not critical in real-life clinical practice. To date, all patients admitted to Emergency Department with acute respiratory failure and/or fever should be considered as a suspected SARS-CoV-2 infection [2-3], and an early recognition of etiology and the prompt therapeutic management are crucial to improve survival [4-5]. From March to July 2020, we performed a prospective, multicenter study (RESILIENCY study). During the study period, all patients hospitalized for suspected or confirmed COVID-19 were prospectively recruited in 3 large hospitals in Rome, Italy. All patients with suspected SARS-CoV-2 infection, admitted to the hospital in case of fever and/or hypoxemic respiratory failure (PaO2 <60 mmHg at rest in ambient air) or of exacerbation of underlying diseases or severe symptoms not manageable outside the hospital, were evaluated according to a predefined protocol (see Figure 1). Overall, 653 patients were included in the study: 309 (47.3%) patients with confirmed COVID-19 and 344 (52.7%) without COVID-19, hospitalized for other causes. Baseline characteristics and outcomes of the study population showed that the main causes of hospitalization among patients without COVID-19 were: acute heart failure (47%), bacterial pneumonia (38.5%), and pulmonary embolism (9.2%). Overall, 67 (21.7%) patients of COVID-19 group and 45 (13.1%) hospitalized for other causes were admitted to intensive care unit; 30-day mortality was observed in 59 (19%) patients of COVID-19 group and 62 (18%) of non-COVID-19 group. The multivariate analysis about risk factors for COVID-19 etiology at time of hospitalization showed that dry cough (OR 3.76, CI 95% 1.98-7.92, P<0.001), duration of fever>3 days (OR 5.21, CI 95% 2.34-9.21, P<0.001), lymphocytopenia (OR 1.98, CI 95% Downloaded from https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciaa1745/5989494 by Sapienza Università di Roma user on 01 December 2020 Accepted Manuscript 3 1.27-4.22, P=0.002) and PaO2/FiO2 ratio<250 (OR 4.98, CI 95% 2.22-9.71, P<0.001) were independently associated with COVID-19 etiology, while procalcitonin value>1 ng/ mL (OR 0.21, CI 95% 0.08-0.82, p<0.001), and lactate>2 mmol/L (OR 0.41, CI 95% 0.15-0.77, p<0.001) were associated with non-COVID-19 etiology. Finally, analysis about predictors of 30-day mortality showed that age (per-year increase OR 1.33; CI 95% 1.11-2.10; p<0.001), cardiovascular disease (OR 4.58; CI 95% 2.07-8.25; p<0.001), and ICU admission (OR 2.1; CI 95% 1.48-4.4; p<0.001) were independently associated with all-cause 30-day mortality, while the use of low-molecularweight heparin (OR 0.22, CI 95% 0.03-0.45, p=0.002) was associated with survival. The findings of the present study can be summarized as follows:1) the prompt identification of specific clinical characteristics (like dry cough or duration of fever>3 days), and laboratory findings (like lymphocytopenia, PaO2/FiO2 ratio<250, procalcitonin value>1 ng/ mL, and lactate>2 mmol/L) can help physicians to distinguish rapidly between COVID19 or other etiologies [6]; 2) the application of a standard approach to management of patients with acute respiratory failure and/or fever associated with the knowledge of clinical and laboratory characteristics of COVID-19 can early drive physicians to therapeutic choices; and 3) age, cardiovascular disease, and ICU admission show an independent association with all-cause 30-day mortality [7], while the use of low-molecular-weight heparin was associated with survival [8]. In conclusion, COVID-19 syndrome is characterized by a heterogeneous clinical, laboratoristic, and radiological presentation, especially at its onset [9]. However, the application of a standard approach to management of patients with acute respiratory failure and/or fever and the knowledge of clinical and laboratory characteristics of COVID-19 can early drive therapeutic choic