Cancellation properties in Hall magnetohydrodynamics with a strong guide magnetic field.

We present a signed measure analysis of compressible Hall magnetohydrodynamic turbulence with an external guide field. Signed measure analysis allows us to characterize the scaling behavior of the sign-oscillating flow structures and their geometrical properties (fractal dimensions of structures). A reduced numerical model, valid when a strong guide magnetic field is present, is used here. In order to discuss the effect of the Hall term, different values for the ion skin depth are considered in the simulations. Results show that as the Hall term is increased, the fractal dimension of the current and vorticity sheets decreases. This observation, together with previous analysis of the same fields, provides a comprehensive description of the effect of the Hall force on the formation of structures. Two main processes are identified, namely, the widening and unraveling of the sheets.

Ganciclovir therapy for symptomatic congenital cytomegalovirus infection in infants: a two-regimen experience.

The efficacy of two regimens of ganciclovir therapy was evaluated in 12 infants with symptomatic congenital cytomegalovirus (CMV) infection. Virologic investigations included culture from urine, saliva, and cerebrospinal fluid, detection of CMV DNA by polymerase chain reaction, and detection of CMV class-specific antibodies (IgG, IgA, IgM) by enzyme immunoassays. Six infants were given ganciclovir, 5 mg/kg twice daily for 2 weeks (group 1); the other six infants were given 7.5 mg/kg twice daily for 2 weeks and 10 mg/kg three times weekly for 3 months (group 2). In group 1 the CMV cultures of specimens from three infants became sterile; two of these infants also had negative results on CMV DNA studies; results of culture and CMV DNA study were still positive after ganciclovir therapy in the remaining three infants. Subsequently, normal outcome was observed in only two patients. In group 2, all infants had negative CMV-culture and CMV DNA results; clinical improvement was evident in five infants, one of whom had later development of mild psychomotor retardation. In another infant, severe psychomotor retardation and hearing loss developed after transient improvement developed. These preliminary data indicate that a ganciclovir regimen including a higher dose and more prolonged therapy might be more effective in infants with symptomatic congenital CMV infection.