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We consider a long-term time optimal consumption and investment problem where an investor wants to maximize the expected power utility of consumption. We treat a stochastic factor model that the mean returns of risky assets depend linearly on underlying economic factors formulated as the solutions of linear stochastic differential equations. We also treat the partial information case that the investor can not observe the factor process and use only past information of risky assets. Then, our problem is formulated as a stochastic control problem with partial information. Using the martingale method, we construct the optimal strategy and obtain the optimal value explicitly. [ABSTRACT FROM AUTHOR]

In this paper, we are interested in the optimal investment and reinsurance strategies of an insurer with delay under the $ 4/2 $ stochastic volatility model. Indeed, the objective of the insurer is to maximize the expected power utility of the terminal wealth and the average wealth on finite time horizon. The other objective is to maximize the growth rate of expected power utility per unit time on infinite time horizon. The wealth of the insurer is described by an approximation of the classical Cramér–Lundberg process. Then, these problems can be formulated as stochastic control problems with delay. A pair of forward-backward stochastic differential equations that are derived via the stochastic maximum principle has an explicit solution obtained by solving a Riccati differential equation. So, the optimal strategy of the finite time horizon problem can be constructed explicitly. And, by investigating asymptotics of the Riccati equation, the infinite time horizon problem can be solved explicitly. Finally, we present some numerical results to illustrate our model, optimal strategies and sensitivities of some parameters. [ABSTRACT FROM AUTHOR]

Introduction: Recently, antimicrobial resistance has received considerable attention. Broad-spectrum antimicrobial agents are recommended as the initial therapy for post-operative intra-abdominal infections. However, at our institution, we have adopted a tactic of initially treating post-operative intra-abdominal complications with relatively narrow-spectrum antimicrobial agents, such as second-generation cephalosporins. In the present study, we aimed to retrospectively analyze the use of antimicrobial agents and the resulting treatment outcomes in patients with intra-abdominal complications after gastrectomy at our facility. Methods: We conducted a retrospective observational study of patients treated with antibiotic agents for intra-abdominal infectious complications after gastrectomy between 2011 and 2021. We determined the proportion of "initial treatment failures" associated with the initial administration of antibiotic agents for post-operative intra-abdominal complications. Results: Post-operative intra-abdominal infections were observed in 29 patients. Broad-spectrum antimicrobial agents were not administered. We successfully treated 19 patients. Initial treatment failure was observed in 10 patients, of whom five experienced failure due to bacterial resistance to the initial antimicrobial agent. All 10 patients who experienced initial treatment failure were discharged after drainage procedures or other treatments. There were no deaths due to post-operative complications. Cefmetazole was used as the initial antimicrobial agent in 27 of the 29 patients. Conclusions: Considering that all patients with post-gastrectomy intra-abdominal infections were successfully treated using relatively narrow-spectrum antimicrobial agents, and initial treatment failure due to antimicrobial-resistant pathogens was 17.2%, the use of narrow-range antimicrobial agents for intra-abdominal infections after gastrectomy can be deemed appropriate.