Three-dimensional computational fluid dynamics analysis of an electric submerged arc furnace.

A computational fluid dynamics (CFD) method is proposed to analyze the operation of a submerged electric arc furnace (SAF) used in ferronickel production. A three-dimensional mathematical model was used for the time-dependent solution of the fluid flow, heat transfer and electromagnetic phenomena. The slag's physical properties, which play a crucial role in the SAF operation, were previously determined using classical molecular dynamics simulations and empirical relationships. The analysis revealed that the main slag properties affecting SAF operation are density, viscosity and electrical conductivity-the latter two being mutually dependent. The high electrical conductivity values of the slag favor melting via the high Joule heat produced within the slag region. Calculation of the dimensionless Péclet and Reynolds numbers revealed that the slag velocities play a decisive role in heat transfer and further indicate that the slag flow is laminar. The average slag velocity calculated 0.0001 m/s with maxima in the vicinity of the electrodes.

Persistence of amygdala gamma oscillations during extinction learning predicts spontaneous fear recovery.

Extinction of auditory fear conditioning induces a temporary inhibition of conditioned fear responses that can spontaneously reappear with the passage of time. Several lines of evidence indicate that extinction learning relies on the recruitment of specific neuronal populations within the basolateral amygdala. In contrast, post-extinction spontaneous fear recovery is thought to result from deficits in the consolidation of extinction memory within prefrontal neuronal circuits. Interestingly, recent data indicates that the strength of gamma oscillations in the basolateral amygdala during auditory fear conditioning correlates with retrieval of conditioned fear responses. In the present manuscript we evaluated the hypothesis that post-extinction spontaneous fear recovery might depend on the maintenance of gamma oscillations within the basolateral amygdala by using single unit and local field potential recordings in behaving mice. Our results indicate that gamma oscillations in the basolateral amygdala were enhanced following fear conditioning, whereas during extinction learning gamma profiles were more heterogeneous despite similar extinction learning rates. Remarkably, variations in the strength of gamma power within the basolateral amygdala between early and late stages of extinction linearly predicted the level of post-extinction spontaneous fear recovery. These data suggest that maintenance of gamma oscillations in the basolateral amygdala during extinction learning is a strong predictive factor of long term spontaneous fear recovery.

Effect of meteorological variables on the incidence of lower urinary tract infections.

Several types of infections involving the respiratory tract have a seasonal variation. We further examined whether lower urinary tract infections (UTIs) are associated with meteorological parameters. We retrospectively evaluated the correlation of the weekly percentage of house call visits for lower UTIs (relatively to all house call visits, excluding those for respiratory tract infections), performed by "SOS Doctors" specialized physicians in Attica, Greece (1/11/2000-18/1/2005), with the average weekly temperature and humidity, recorded at the same area, 3 days earlier. Three thousand two hundred and twenty-one visits for lower UTIs were recorded in patients of 62.9 +/- 21.0 years of age. House call visits for lower UTIs, as defined above, correlated with the average weekly temperature (Spearman's rho+0.468) and humidity (Spearman's rho -0.394); similarly, if respiratory tract infections were not excluded from the calculations (Spearman's rho +0.491 and -0.406, respectively); or if a 2-day lag between measurements was used (Spearman's rho +0.468 and -0.386, respectively). All the above findings were significant (p<0.001). In conclusion, in a population that consisted mainly of patients of advanced age, higher temperature and decreased humidity are associated with an increase in house call visits for lower UTIs. The awareness of this association may facilitate preventive public health strategies. [corrected]