Density of states for dilute nitride systems: calculation of lifetime broadening.

We present calculations for the band structure of bulk and confined quantum well and quantum wire GaInNAs structures. To treat this non-randomly alloyed material system we follow previous approaches in using an Anderson impurity model where the nitrogen localized states interact with the GaInAs conduction band states. We solve this model using Matsubara Green's functions and the associated self-energies which produce a complex band structure where both the real and imaginary components depend on the concentration of nitrogen. In particular this approach gives a definite nitrogen dependent lifetime broadening and is different from previous work in that no artificial input parameters are used. The density of states of the conduction band, derived from these functions, is strongly altered by interaction with the nitrogen states. The density of states is required for further optical and transport investigations involving this system.

Cefetamet pivoxil in paediatric patients suffering from lower respiratory tract infections.

A prospective, randomized comparative trial was carried out in 31 children suffering from lower respiratory tract infections, mainly bronchopneumonia or pneumonia. Twenty-one children received oral cefetamet pivoxil in a dose of 20 mg/kg/day (10 children) or 40 mg/kg/day (11 children), and 10 children 30 mg cefaclor/kg/day for 7 days. Clinical signs and symptoms, i.e. fever, dyspnoea, altered breath sounds and cough, subsided during treatment with both cefetamet pivoxil treatment doses in all patients. All X-ray findings and blood leucocytosis normalized, while 1 out of the 10 children to whom 30 mg cefaclor/kg/day was administered deteriorated from bronchopneumonia to pneumonitis during treatment. Treatment was stopped due to vomiting in 1 patient receiving the 40 mg cefetamet pivoxil/kg/day dose.