State Space Realization of Model Predictive Controllers Without Active Constraints

To enable the use of traditional tools for analysis of multivariable controllers such as model predictive control (MPC), we develop a state space formulation for the resulting controller for MPC without constraints or assuming that the constraints are not active. Such a derivation was not found in the literature. The formulation includes a state estimator. The MPC algorithm used is a receding horizon controller with infinite horizon based on a state space process model. When no constraints are active, we obtain a state feedback controller, which is modified to achieve either output tracking, or a combination of input and output tracking. When the states are not available, they need to be estimated from the measurements. It is often recommended to achieve integral action in a MPC by estimating input disturbances and include their effect in the model. We show that to obtain offset free steady state the number of estimated disturbances must equal the number of measurements. The estimator is included in the controller equation, and we obtain a formulation of the overall controller with the set-points and measurements as inputs, and the manipulated variables as outputs. One application of the state space formulation is in combination with the process model to obtain a closed loop model. This can for example be used to check the steady-state solution and see whether integral action is obtained or not

Polypharmacy and potentially inappropriate medication use in geriatric oncology.

Polypharmacy is a highly prevalent problem in older persons, and is challenging to assess and improve due to variations in definitions of the problem and the heterogeneous methods of medication review and reduction. The purpose of this review is to summarize evidence regarding the prevalence and impact of polypharmacy in geriatric oncology patients and to provide recommendations for assessment and management. Polypharmacy has somewhat variably been incorporated into geriatric assessment studies in geriatric oncology, and polypharmacy has not been consistently evaluated as a predictor of negative outcomes in patients with cancer. Once screened, interventions for polypharmacy are even more uncertain. There is a great need to create standardized interventions to improve polypharmacy in geriatrics, and particularly in geriatric oncology. The process of deprescribing is aimed at reducing medications for which real or potential harm outweighs benefit, and there are numerous methods to determine which medications are candidates for deprescribing. However, deprescribing approaches have not been evaluated in older patients with cancer. Ultimately, methods to identify polypharmacy will need to be clearly defined and validated, and interventions to improve medication use will need to be based on clearly defined and standardized methods

The views of older women towards mammographic screening: a qualitative and quantitative study

Purpose: Mammographic screening has improved breast cancer survival in the screened age group. This improved survival has not been seen in older women (>70 years) where screening uptake is low. This study explores the views, knowledge and attitudes of older women towards screening. Methods: Women (>70) were interviewed about breast screening. Interview findings informed the development of a questionnaire which was sent to 1000 women (>70) to quantify their views regarding screening. Results: Twenty-six women were interviewed and a questionnaire designed. The questionnaire response rate was 48.3% (479/992). Over half (52.9%, 241/456) of respondents were unaware they could request mammography by voluntary self-referral and were unaware of how to arrange this. Most (81.5% 383/470) had not attended breast screening since turning 70. Most (75.6%, 343/454) felt screening was beneficial and would attend if invited. Most, (90.1%, 412/457) felt screening should be offered to all women regardless of age or health. Conclusions: There is a lack of knowledge about screening in older women. The majority felt that invitation to screening should be extended to the older age group regardless of age or health. The current under-utilised system of voluntary self referral is not supported by older women

Offset-free receding horizon control of constrained linear systems

The design of a dynamic state feedback receding horizon controller is addressed, which guarantees robust constraint satisfaction, robust stability and offset-firee control of constrained linear systems in the presence of time-varying setpoints and unmeasured disturbances. This objective is obtained by first designing a dynamic linear offset-free controller and computing an appropriate domain of attraction for this controller. The linear (unconstrained) controller is then modified by adding a perturbation term, which is computed by a (constrained) robust receding horizon controller. The receding horizon controller has the property that its domain of attraction contains that of the linear controller. In order to ensure robust constraint satisfaction, in addition to offset-free control, the transient, as well as the limiting behavior of the disturbance and setpoint need to be taken into account in the design of the receding horizon controller. The fundamental difference between the results and the existing literature on receding horizon control is that the transient effect of the disturbance and set point sequences on the so-called "target calculator" is explicitly incorporated in the formulation of the receding horizon controller. An example of the control of a continuous stirred-tank reactor is presented. (c) 2005 American Institute of Chemical Engineers

Automatic differentiation for gradient-based optimization of radiatively heated microelectronics manufacturing equipment

Automatic differentiation is applied to the optimal design of microelectronic manufacturing equipment. The performance of nonlinear, least-squares optimization methods is compared between numerical and analytical gradient approaches. The optimization calculations are performed by running large finite-element codes in an object-oriented optimization environment. The Adifor automatic differentiation tool is used to generate analytic derivatives for the finite-element codes. The performance results support previous observations that automatic differentiation becomes beneficial as the number of optimization parameters increases. The increase in speed, relative to numerical differences, has a limited value and results are reported for two different analysis codes

Recent advances in the management of gastric adenocarcinoma patients [version 1; referees: 2 approved]

Gastric adenocarcinoma (GAC) is one of the most aggressive malignancies and has a dismal prognosis. Therefore, multimodality therapies to include surgery, chemotherapy, targeted therapy, immunotherapy, and radiation therapy are needed to provide advantage. For locally advanced GAC (>cT1B), the emerging strategies have included preoperative chemotherapy, postoperative adjuvant chemotherapy, and (occasionally) postoperative chemoradiation in various regions. Several novel therapies have been assessed in clinical trials, but only trastuzumab and ramucirumab (alone and in combination with paclitaxel) have shown overall survival advantage. Pembrolizumab has been approved by the US Food and Drug Administration on the basis of response rate only for patients with microsatellite instability (MSI-H) or if PD-L1 expression is positive (≥1% labeling index in tumor/immune cells in the presence of at least 100 tumor cells in the specimen). Nivolumab has been approved in Japan on the basis of a randomized trial showing significant survival advantage for patients who received nivolumab compared with placebo in the third or later lines of therapy. The cure rate of patients with localized GAC in the West is only about 40% and that for metastatic cancer is very poor (only 2–3%). At this stage, much more target discovery is needed through molecular profiling. Personalized therapy of patients with GAC remains a challenge

Robot-assisted laparoscopic transperitoneal pelvic lymphadenectomy and metastasectomy for melanoma: initial report of two cases

Robotic pelvic lymphadenectomy is a well established procedure in the urologic and gynecologic literature. To our knowledge robotic pelvic lymphadectomy for metastatic melanoma has yet to be described. Herein we present the first report of robot-assisted pelvic lymphadenectomy in malignant melanoma. After placement of six laparoscopic ports (12 mm camera, three 8-mm robotic ports, 12-mm and 5-mm assistant ports) the DaVinci S robot (Intuitive Surgical, CA, USA) was docked in standard fashion with the patient in low lithotomy. In both cases the patients had enlarged pelvic lymph nodes on computed tomography and complete excision of these masses was accomplished along with complete lymphadenectomy extending from Cooper’s ligament to just below the hypogastric artery in case 1 and to level of the bifurcation of aorta in case 2. A PK Maryland Dissector and monopolar scissors were used for dissection. Both patients were discharged on postoperative day #1. Robotic pelvic lymphadenectomy can be safely used for management of patients with metastatic melanoma involving the pelvic lymph nodes. Compared with the standard open procedure, pelvic lymphadenectomy with robotic assistance is associated with excellent vision and minimum morbidity