Internal model-based control for integrating processes.

Internal model-based control (IMC) has been shown to possess many advantages over PID control, particularly in the presence of significant process deadtime. Implementation of IMC is simplified in a large class of industrial applications where the process dynamics can be adequately characterized by a simple first-order model requiring only estimates of process gain, lag time constant, and deadtime for implementing the controller design. Tuning of the controller is easily and intuitively done by adjusting the filter time constant; decreasing the time constant speeds up the closed-loop response, and increasing it yields generally a slower but more stable response.

Results of treatment of children with recurrent medulloblastoma/primitive neuroectodermal tumors with lomustine, cisplatin, and vincristine.

Primitive neuroectodermal tumors/medulloblastoma (PNET/MB) are the most common posterior fossa tumors in childhood. Despite surgery and radiation therapy, 40% to 50% of children with PNET/MB will have recurrent disease. Various chemotherapeutic agents are transiently effective in recurrent PNET/MB, but long-lasting responses are rarely attainable.

Late recurrence of primitive neuroectodermal tumor/medulloblastoma.

The period of risk for recurrence of primitive neuroectodermal tumor/medulloblastoma (PNET/MB) is not clearly defined. With current treatment since more than 50% of children with PNET/MB can be expected to survive for at least 5 years after diagnosis, determining the evidence of "late" recurrence is of increasing concern. Collins has stated that patients with embryonal tumors who survive, disease free, for a period of time equal to the age at diagnosis plus 9 months can be declared cured.

Results of the treatment of children with recurrent gliomas with lomustine and vincristine.

Gliomas comprise over 50% of all childhood brain tumors. Treatment of recurrent childhood gliomas has been disappointing and the effectiveness of therapy has been difficult to judge because of the variable natural history of the disease. Information gathered recently has suggested that treatment with [1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea)] (CCNU) and vincristine (VCR) after radiotherapy is effective in prolonging survival in children with newly diagnosed anaplastic gliomas.