Following Gajardo et al. (2008) SIAM J Control Optim 47(6):2827-2856, we allow the control variable to be a bounded measurable function of time combined with possible impulses associated with instantaneous dilutions. For this problem, the extremal trajectories of the singular arc type are characterized as the strategies used to maintain the substrate at a constant level. Since this optimization problem is difficult to solve, this characterization provides a valuable tool for investigating

the optimality of various feeding strategies. Our aim is thus to illustrate the use of this tool by proposing potential optimal feeding strategies, PF-6463922 manufacturer which may then be compared with other more intuitive strategies. This aim was accomplished via several numerical experiments in which two specific strategies are compared.”
“Since their discovery, fermentation processes have gone along not only with the industrial Selleckchem BI 2536 beverages production and breweries, but since the times of Alexander Fleming, they have become a crucial part of the health care due to antibiotics production. However, complicated dynamics and strong nonlinearities cause that the production with the use of linear

control methods achieves only suboptimal yields. From the variety of nonlinear approaches, gradient method has proved the ability to handle these issues-nevertheless, its potential in DAPT supplier the field of fermentation processes has not been revealed completely. This paper describes constant vaporization control strategy based on a double-input optimization approach with a successful reduction to a single-input optimization task. To accomplish this, model structure used in the previous work is modified so that it corresponds with the new optimization strategy. Furthermore, choice of search step is explored and various alternatives are evaluated

and compared.”
“The factors that affect the 6-month continuation of adjuvant chemotherapy with S-1 have not been fully evaluated. The objective of this retrospective study was to clarify the risk factors for 6-month continuation of S-1 adjuvant chemotherapy.

The study selected patients who underwent curative D2 surgery for gastric cancer, were diagnosed with stage 2 or 3 disease, had a serum creatinine level of a parts per thousand currency sign1.2 mg/dl, and received adjuvant S-1 between June 2002 and March 2011.

One hundred of these patients were eligible for the present study. A comparison of 6-month continuation of S-1 stratified by various clinical factors, using the log-rank test, revealed a marginally significant difference in creatinine clearance (CCr) between those patients who continued for 6 months and those who did not. A CCr of 60 ml/min was regarded as the critical point.