Shadow prices and well-posedness in the problem of optimal investment and consumption with transaction costs

We revisit the optimal investment and consumption model of Davis and Norman (1990) and Shreve and Soner (1994), following a shadow-price approach similar to that of Kallsen and Muhle-Karbe (2010). Making use of the completeness of the model without transaction costs, we reformulate and reduce the Hamilton-Jacobi-Bellman equation for this singular stochastic control problem to a non-standard free-boundary problem for a first-order ODE with an integral constraint. Having shown that the free boundary problem has a smooth solution, we use it to construct the solution of the original optimal investment/consumption problem in a self-contained manner and without any recourse to the dynamic programming principle. Furthermore, we provide an explicit characterization of model parameters for which the value function is finite.Comment: 31 pages, 20 figure

State-of-the-Art Design Technique of a Single-Channel Pump for Wastewater Treatment

A single-channel pump, which is commonly used for wastewater treatment, with a single-channel impeller can effectively prevent performance reduction or damage caused by foreign substances. However, the design methods for this special type of pump are different and more difficult to realize than those for general pumps. In this chapter, a state-of-the-art design technique for a single-channel pump is introduced for realizing high efficiency and low-fluid-induced vibration. In other words, advanced multidisciplinary design optimization techniques combined with unsteady flow analysis are introduced and discussed in detail to simultaneously improve hydraulic efficiency and reduce flow-induced vibration, considering the impeller-volute interaction of a single-channel pump

Medial Meniscal Tears in Anterior Cruciate Ligament-Deficient Knees: Effects of Posterior Tibial Slope on Medial Meniscal Tear

PURPOSE: To evaluate the incidence of meniscal tears in patients with chronic anterior cruciate ligament (ACL)-deficient knees, and to determine the influence of posterior tibial slope (PTS) on medial meniscal tears in ACL-deficient knees. MATERIALS AND METHODS: We reviewed 174 patients (174 knees) with a mean age of 30.7 years who underwent ACL reconstruction for chronic ACL tears. We divided the patients into two groups: low group (135 knees with a PTS or =13degrees). RESULTS: The incidence of medial meniscus tears was 44% (77/174), and that of lateral meniscus tears was 35% (61/174). The mean PTS in patients with medial meniscal tears was 11.4degrees+/-3.0degrees, whereas that in patients without medial meniscal tears was 9.8degrees+/-2.4degrees. The incidence of meniscal tears was 57.8% (78/135) in the low group and 89.7% (35/39) in the high group (p or =13degrees is a risk factor for secondary medial meniscal tears in ACL-deficient knees. So, we suggest that PTS is one of the considerations for determining early ACL reconstruction to prevent secondary meniscal tears.ope

Estimation of axial curvature of anterior sclera: correlation between axial length and anterior scleral curvature as affected by angle kappa

Background: Though the development and fitting of scleral contact lenses are expanding steadily, there is no simple method to provide scleral metrics for scleral contact lens fitting yet. The aim of this study was to establish formulae for estimation of the axial radius of curvature (ARC) of the anterior sclera using ocular biometric parameters that can be easily obtained with conventional devices. Methods: A semi-automated stitching method and a computational analysis tool for calculating ARC were developed by using the ImageJ and MATLAB software. The ARC of all the ocular surface points were analyzed from the composite horizontal cross-sectional images of the right eyes of 24 volunteers; these measurements were obtained using anterior segment optical coherence tomography for a previous study (AS-OCT; Visante). Ocular biometric parameters were obtained from the same volunteers with slit-scanning topography and partial coherence interferometry. Correlation analysis was performed between the ARC at 8 mm to the axis line (ARC[8]) and other ocular parameters (including age). With ARC obtained on several nasal and temporal points (7.0, 7.5, 8.0, 8.5, and 9.0 mm from the axis line), univariate and multivariate linear regression analyses were performed to develop a model for estimating ARC with the help of ocular biometric parameters. Results: Axial length, spherical equivalent, and angle kappa showed correlations with temporal ARC[8] (tARC[8]; Pearson’s r = 0.653, −0.579, and −0.341; P = 0.001, 0.015, and 0.015, respectively). White-to-white corneal diameter (WTW) and anterior chamber depth (ACD) showed correlation with nasal ARC[8] (nARC[8]; Pearson’s r = −0.492 and −0.461; P = 0.015 and 0.023, respectively). The formulae for estimating scleral curvatures (tARC, nARC, and average ARC) were developed as a function of axial length, ACD, WTW, and distance from the axis line, with good determinant power (72 − 80 %; SPSS ver. 22.0). Angle kappa showed strong correlation with axial length (Pearson’s r = −0.813, P <0.001), and the different correlation patterns of nasal and temporal ARC with axial length can be explained by the ocular surface deviation represented by angle kappa. Conclusions: Axial length, ACD, and WTW are useful parameters for estimating the ARC of the anterior sclera, which is important for the haptic design of scleral contact lenses. Angle kappa affects the discrepancies between the nasal and temporal scleral curvature.Korea (South). Ministry of Health & Welfare (Projects A084496 and A120018

Study on the effect of a cold environment on the quality of three video laryngoscopes: McGrath MAC, GlideScope Ranger, and Pentax Airway Scope

Objective Several environmental factors influence the prehospital use of video laryngoscopes (VLs). For example, fogging of the VL lens can occur in cold environments, and the low temperature can cause the VLs to malfunction. As relevant research on the effect of environment on VLs is lacking, we aimed to study the effect of a cold environment on three commonly used VLs. Methods McGrath MAC, Pentax Airway Scope (AWS), and GlideScope Ranger were exposed to temperatures of -5°C, -10°C, -20°C, and -25°C for 1 hour each and then applied to a manikin in a thermohydrostat room 5 times. Immediately after turning on the power and inserting the blade, the time until an appropriate glottic image appeared on the screen was measured. Results McGrath MAC was able to accomplish immediate intubation regardless of the temperature drop. However, GlideScope Ranger required an average of 4.9 seconds (-5°C to -20°C) and 10.1 seconds (-25°C) until appropriate images were obtained for intubation. AWS showed adequate image acquisition immediately after blade insertion despite slight fogging at -20°C, but at -25°C, images suitable for intubation did not appear on the screen for an average of 4.7 minutes. Conclusion All three devices appear to be usable without any limitations up to -20°C. However, GlideScope Ranger and AWS may not produce images immediately at temperatures below -25°C. Thus, medical practitioners performing VL in a cold environment should be aware of the characteristics of the VL devices in advance

The Influence of Preoperative Bladder Outlet Obstruction on Continence and Satisfaction in Patients with Stress Urinary Incontinence after Midurethral Sling

Purpose We studied the influence of preoperative bladder outlet obstruction (BOO) on postoperative continence rates and patient satisfaction after the midurethral sling procedure. Methods A total of 159 women who underwent the midurethral sling procedure were evaluated. Using the Blaivas-Groutz nomogram, we assigned the patients were assigned to Group I (n=37, no obstruction), Group II (n=89, mild obstruction), or Group III (n=33, moderate to severe obstruction). Continence rates, patient satisfaction, urinary sensation scale and uroflowmetry were evaluated postoperatively. Results There were no significant differences in continence rates, satisfaction, or postoperative maximal flow rate between the 3 groups. Postoperative urgency was improved after surgery in Groups I and II (P<0.05) but not in Group III. Conclusions BOO does not seem to be a risk factor for failure after the midurethral sling procedure. However, BOO may be considered as a potential factor for persistent storage symptoms after the midurethral sling