Small but slow world: how network topology and burstiness slow down spreading.

While communication networks show the small-world property of short paths, the spreading dynamics in them turns out slow. Here, the time evolution of information propagation is followed through communication networks by using empirical data on contact sequences and the susceptible-infected model. Introducing null models where event sequences are appropriately shuffled, we are able to distinguish between the contributions of different impeding effects. The slowing down of spreading is found to be caused mainly by weight-topology correlations and the bursty activity patterns of individuals.

Density of critical clusters in strips of strongly disordered systems.

We consider two models with disorder-dominated critical points and study the distribution of clusters that are confined in strips and touch one or both boundaries. For the classical random bond Potts model in the large- q limit, we study optimal Fortuin-Kasteleyn clusters using a combinatorial optimization algorithm. For the random transverse-field Ising chain, clusters are defined and calculated through the strong-disorder renormalization group method. The numerically calculated density profiles close to the boundaries are shown to follow scaling predictions. For the random bond Potts model, we have obtained accurate numerical estimates for the critical exponents and demonstrated that the density profiles are well described by conformal formulas.

Rounding of first-order phase transitions and optimal cooperation in scale-free networks.

We consider the ferromagnetic large- q state Potts model in complex evolving networks, which is equivalent to an optimal cooperation problem, in which the agents try to optimize the total sum of pair cooperation benefits and the supports of independent projects. The agents are found to be typically of two kinds: A fraction of m (being the magnetization of the Potts model) belongs to a large cooperating cluster, whereas the others are isolated one man's projects. It is shown rigorously that the homogeneous model has a strongly first-order phase transition, which turns to second-order for random interactions (benefits), the properties of which are studied numerically on the Barabási-Albert network. The distribution of finite-size transition points is characterized by a shift exponent, 1/nu'=0.26(1), and by a different width exponent, 1/nu'=0.18(1), whereas the magnetization at the transition point scales with the size of the network, N, as m approximately N(-x), with x=0.66(1).

Relationships between force-feeding and some physiological parameters in geese bred for fatty liver.

The susceptibility of geese of different genotypes and sexes to force-feeding, some plasma biochemical parameters (thyroid hormones, cholesterol, retinoids, total protein and albumin) of force-fed geese, and the relationship between force-feeding, fat storage and the above-mentioned parameters were studied. Sixty (30 male and 30 female) geese of three genotypes (Hungarian, Landes and their crossbred called Babat Hybrid) were divided in two groups at 12 weeks of age. Geese in one group (5 males and 5 females from each genotype) received mixed feeding ad libitum. Birds in the other group were force-fed with maize. After 3 weeks all birds were bled, blood samples were taken, and the above-mentioned plasma parameters were determined. Thyroxine (T4) levels were significantly lower in force-fed (11.6 +/- 3.5 ng/ml) than in control geese (22.7 +/- 4.09 ng/ml). Plasma triiodothyronine (T3) level was also lower in the force-fed than in the control group, but the difference was not significant (1.87 +/- 0.23 ng/ml and 2.11 +/- 0.28 ng/ml, respectively). Plasma total protein (TP, 45.2 +/- 4.5 g/l), albumin (ALB, 16.51 +/- 2.8 g/l), beta-carotene (BC, 3504 +/- 3107 micrograms/l), retinol (ROL, 1160 +/- 505 micrograms/l), retinyl palmitate (RP, 1745 +/- 405 micrograms/l) and total cholesterol (TCh, 4.32 +/- 0.55 mmol/l) levels were elevated in the force-fed group as compared to the control (TP = 36.4 +/- 5.1 g/l, ALB = 15.6 +/- 0.9 g/l, BC = 1657 +/- 1681 micrograms/l, ROL = 687 +/- 375 micrograms/l, RP = 1398 +/- 607 micrograms/l, and TCh = 2.83 +/- 1.98 mmol/l). All differences were significant except those found for albumin and beta-carotene. No significant sex- or genotype-related effects were observed for these parameters.