Dependence on the thermodynamic state of self-diffusion of pseudo-hard-sphere and Lennard-Jones potentials.

Self-diffusion D in a system of particles that interact with a pseudo-hard-sphere or a Lennard-Jones potential is analyzed. Coupling with a solvent is represented by a Langevin thermostat, characterized by the damping time t_{d}. The hypotheses that D=D_{0}φ is proposed, where D_{0} is the small concentration diffusivity and φ is a thermodynamic function that represents the effects of interactions as concentration is increased. Molecular dynamics simulations show that different values of the noise intensity modify D_{0}, but do not have an effect on φ. This result is consistent with the assumption that φ is a thermodynamic function since the thermodynamic state is not altered by the presence of damping and noise.

Diffusion on a lattice: Transition rates, interactions, and memory effects.

We analyze diffusion of particles on a two-dimensional square lattice. Each lattice site contains an arbitrary number of particles. Interactions affect particles only in the same site, and are macroscopically represented by the excess chemical potential. In a recent work, a general expression for transition rates between neighboring cells as functions of the excess chemical potential was derived. With transition rates, the mean-field tracer diffusivity, D^{MF}, is immediately obtained. The tracer diffusivity, D=D^{MF}f, contains the correlation factor f, representing memory effects. An analysis of the joint probability of having given numbers of particles at different sites when a force is applied to a tagged particle allows an approximate expression for f to be derived. The expression is applied to soft core interaction (different values for the maximum number of particles in a site are considered) and extended hard core.

Application of the Widom insertion formula to transition rates in a lattice.

We consider diffusion of particles on a lattice in the so-called dynamical mean-field regime (memory effects are neglected). Interactions are local, that is, only among particles at the same lattice site. It is shown that a statistical mechanics analysis that combines detailed balance and Widom's insertion formula allows for the derivation of an expression for transition rates in terms of the excess chemical potential. The rates reproduce the known dependence of self-diffusivity as the inverse of the thermodynamic factor. Soft-core interactions and general forms of the excess chemical potential (linear, quadratic, and cubic with the density) are considered.

Dynamic vaccination in partially overlapped multiplex network.

In this work we propose and investigate a strategy of vaccination which we call "dynamic vaccination." In our model, susceptible people become aware that one or more of their contacts are infected and thereby get vaccinated with probability ω, before having physical contact with any infected patient. Then the nonvaccinated individuals will be infected with probability ß. We apply the strategy to the susceptible-infected-recovered epidemic model in a multiplex network composed by two networks, where a fraction q of the nodes acts in both networks. We map this model of dynamic vaccination into bond percolation model and use the generating functions framework to predict theoretically the behavior of the relevant magnitudes of the system at the steady state. We find a perfect agreement between the solutions of the theoretical equations and the results of stochastic simulations. In addition, we find an interesting phase diagram in the plane ß-ω, which is composed of an epidemic and a nonepidemic phase, separated by a critical threshold line ß_{c}, which depends on q. As q decreases, ß_{c} increases, i.e., as the overlap decreases, the system is more disconnected, and therefore more virulent diseases are needed to spread epidemics. Surprisingly, we find that, for all values of q, a region in the diagram where the vaccination is so efficient that, regardless of the virulence of the disease, it never becomes an epidemic. We compare our strategy with random immunization and find that, using the same amount of vaccines for both scenarios, we obtain that the spread of disease is much lower in the case of dynamic vaccination when compared to random immunization. Furthermore, we also compare our strategy with targeted immunization and we find that, depending on ω, dynamic vaccination will perform significantly better and in some cases will stop the disease before it becomes an epidemic.

Cascading Failures in Interdependent Networks with Multiple Supply-Demand Links and Functionality Thresholds.

Various social, financial, biological and technological systems can be modeled by interdependent networks. It has been assumed that in order to remain functional, nodes in one network must receive the support from nodes belonging to different networks. So far these models have been limited to the case in which the failure propagates across networks only if the nodes lose all their supply nodes. In this paper we develop a more realistic model for two interdependent networks in which each node has its own supply threshold, i.e., they need the support of a minimum number of supply nodes to remain functional. In addition, we analyze different conditions of internal node failure due to disconnection from nodes within its own network. We show that several local internal failure conditions lead to similar nontrivial results. When there are no internal failures the model is equivalent to a bipartite system, which can be useful to model a financial market. We explore the rich behaviors of these models that include discontinuous and continuous phase transitions. Using the generating functions formalism, we analytically solve all the models in the limit of infinitely large networks and find an excellent agreement with the stochastic simulations.

Cascading failures in interdependent networks with finite functional components.

We present a cascading failure model of two interdependent networks in which functional nodes belong to components of size greater than or equal to s. We find theoretically and via simulation that in complex networks with random dependency links the transition is first order for s≥3 and continuous for s=2. We also study interdependent lattices with a distance constraint r in the dependency links and find that increasing r moves the system from a regime without a phase transition to one with a second-order transition. As r continues to increase, the system collapses in a first-order transition. Each regime is associated with a different structure of domain formation of functional nodes.

Recovery of Interdependent Networks.

Recent network research has focused on the cascading failures in a system of interdependent networks and the necessary preconditions for system collapse. An important question that has not been addressed is how to repair a failing system before it suffers total breakdown. Here we introduce a recovery strategy for nodes and develop an analytic and numerical framework for studying the concurrent failure and recovery of a system of interdependent networks based on an efficient and practically reasonable strategy. Our strategy consists of repairing a fraction of failed nodes, with probability of recovery γ, that are neighbors of the largest connected component of each constituent network. We find that, for a given initial failure of a fraction 1 - p of nodes, there is a critical probability of recovery above which the cascade is halted and the system fully restores to its initial state and below which the system abruptly collapses. As a consequence we find in the plane γ - p of the phase diagram three distinct phases. A phase in which the system never collapses without being restored, another phase in which the recovery strategy avoids the breakdown, and a phase in which even the repairing process cannot prevent system collapse.

Publisher's Note: Cascading failures in interdependent networks with finite functional components [Phys. Rev. E 94, 042304 (2016)].

This corrects the article DOI: 10.1103/PhysRevE.94.042304.

[Exercise two-dimensional echocardiography in recent myocardial infarction. Is it useful in the detection of multivessel disease?]. / L'ecocardiografia bidimensionale da sforzo nell'infarto miocardico recente. E utile nell'individuazione di malattia multivascolare?

Exercise two-dimensional echocardiography (2D-ECHO) can be used to detect coronary artery disease in patients (pts) by the development of stress-induced transient asynergy in areas without wall motion abnormalities when at rest. The aim of the study is to verify the accuracy of exercise 2D-ECHO in the identification of high risk pts with multivessel disease after the first acute myocardial infarction (AMI). Technically adequate 2D-ECHO examinations were obtained in 21 of 28 (75%) consecutive patients after acute myocardial infarction. 30-50 days after acute myocardial infarction, these 21 pts (19 males and 2 females, mean age +/- SD = 54.3 +/- 8.7) underwent 2D-ECHO during bicycle exercise in supine position. The marker of multivessel disease was the development, during the stress test, of new areas of asynergy not adjacent to the infarcted area (i.e. transient remote asynergy). Two months after acute myocardial infarction all pts underwent coronary angiography to verify the severity of coronary obstruction (reduction of luminal diameter greater than or equal to 75% in the non infarct related vessel).(ABSTRACT TRUNCATED AT 250 WORDS)

Red blood cell Na content, Na, Li-countertransport, family history of hypertension and blood pressure in school children.

This study focuses on the relationship between some aspects of intra-erythrocytic sodium metabolism (intra-erythrocytic Na content, Na,Li-countertransport), blood pressure, and family history of hypertension, in a group of 84 randomly selected school children (45 males, 39 females). Na,Li-countertransport was significantly related to both systolic blood pressure (SBP) and diastolic blood pressure (DBP) only in boys at the univariate level, but both of these associations lost statistical significance after the possible confounding role of weight and height were taken into consideration. In both sexes, participants with a family history of hypertension had similar values of both intra-erythrocytic Na content and Na,Li-countertransport to participants with no family history. We conclude that family history of hypertension does not seem to play an important role in the determination of either intra-erythrocytic Na content or Na,Li-countertransport at this age. Although the positive association between Na,Li-countertransport and blood pressure observed in adult males is already present in childhood, this probably is still, at least in part, dependent upon body size.

Hypertension, non-insulin-dependent diabetes, and intracellular sodium metabolism.

The present study was designed to investigate whether non-insulin-dependent diabetic hypertensive patients exhibit abnormalities in intracellular sodium metabolism similar to those described for essential hypertensive patients. Both normotensive and hypertensive non-insulin-dependent diabetic patients had similar average values of both Na+-Li+ countertransport and Na+-K+ cotransport compared with nondiabetic controls. Within the group of diabetic patients, hypertensive patients did not exhibit any abnormalities in either of the sodium transport pathways studied. The possible implications of these findings are addressed.

Outward Na-K-Cl cotransport in human red blood cells: a methodological evaluation of method for epidemiologic investigations.

The present report evaluates a method for the determination of the maximal velocity of the outward sodium, potassium, chlorine (Na-K-Cl) cotransport in erythrocytes. The loading procedure was carried out using the ionophore nystatin. The technical error for this assay, based on concurrent analysis of randomized blind duplicate samples, was 8.04% of the sample mean and 27.5% of the sample standard deviation. The assay was stable over time and reproducible. Fasting was not necessary. The ratio of intra- to interindividual variances was small. The cells can be safely preserved in an appropriate preservation solution without modification of the ion transport assay. The assay appears to be adequate for use in large-scale field trials.

Alcohol consumption and blood pressure in school children.

The present report focuses on the relationship between alcohol consumption, estimated with the use of a seven day food record, and blood pressure in a group of 203 male and female school children with a mean age of 11 year. 50.5% of the male and 39.4% of the female children reported use of alcoholic beverages. The average weekly ethanol consumption in these regular drinkers was 73.9 ml/week for boys and 53.1 ml/week for girls. The results of the analyses fail to show any significant association between alcohol consumption and blood pressure levels. The possibility of the association between alcohol and hypertension being dependent on advanced age is discussed in view of the present results and previously published reports.

Intracellular ion metabolism in erythrocytes and uraemia: the effect of different dialysis treatments.

The present report focuses on some aspects of the intra-erythrocytic cation metabolism (e.g. the maximal velocity of the Na+-Li+ countertransport and Na+/K+/Cl- cotransport) in uraemic patients on different dialysis treatments. Patients undergoing dialysis treatment [continuous ambulatory peritoneal dialysis (CAPD) or haemodialysis (HD)] overall showed higher Na+-Li+ countertransport than controls. With regard to Na+/K+/Cl- cotransport, CAPD patients and controls did not differ and both showed, on average, higher values than HD patients. A subgroup of HD patients was studied before and after dialysis. No significant overall changes were detected as a result of the dialysis process with regard to Na+/K+/Cl- cotransport. Na+-Li+ countertransport was significantly reduced by dialysis and a distinctly different response to dialysis was evident according to predialysis values. Patients with high values of Na+-Li+ countertransport showed a significant reduction in this parameter while patients with normal values showed no effect. No distinct association was detected between alteration in either Na+-Li+ countertransport or Na+/K+/Cl- cotransport and the clinical characteristics of the patients. It is concluded that uraemia and/or dialysis influences the maximal velocity of the parameters under investigation. The effect on Na+-Li+ countertransport seems to be similar for both CAPD and HD, while Na+/K+/Cl- cotransport is not altered in CAPD patients.