Learning a Low-Dimensional Representation of a Safe Region for Safe Reinforcement Learning on Dynamical Systems.

For the safe application of reinforcement learning algorithms to high-dimensional nonlinear dynamical systems, a simplified system model is used to formulate a safe reinforcement learning (SRL) framework. Based on the simplified system model, a low-dimensional representation of the safe region is identified and used to provide safety estimates for learning algorithms. However, finding a satisfying simplified system model for complex dynamical systems usually requires a considerable amount of effort. To overcome this limitation, we propose a general data-driven approach that is able to efficiently learn a low-dimensional representation of the safe region. By employing an online adaptation method, the low-dimensional representation is updated using the feedback data to obtain more accurate safety estimates. The performance of the proposed approach for identifying the low-dimensional representation of the safe region is illustrated using the example of a quadcopter. The results demonstrate a more reliable and representative low-dimensional representation of the safe region compared with previous works, which extends the applicability of the SRL framework.

In-Hospital Bleeding in Elderly Patients With Acute Coronary Syndrome: Are Potent Antiplatelet Agents Safe?

Despite implementation of new interventional techniques and therapeutic advances, elderly patients with acute coronary syndrome (ACS) continue to be susceptible to in-hospital bleeding compared with younger ones. Thus, we investigated the incidence of in-hospital bleeding events and associated risk factors in elderly (≥ 75°years) ACS patients. We also wanted to define the bleeding sites, characteristics, and associated mortality. Bleeding Academic Research Consortium (BARC) classification type 2, 3, or 5 was used to define bleeding events. Overall, 539 patients were included in the study (mean age: 82.5 ± 4.8°years; 282 (52.3%) females). Of these patients, 69 (12.8%) developed in-hospital bleeding. Factors that were independently related with in-hospital bleeding were age (odds ratio (OR): 1.08; 95% confidence interval (CI): 1.011.14, P = .01), acute kidney injury (OR: 3.66; 95% CI: 2.016.69; P < .01), tirofiban (OR: 4.43; 95% CI: 1.7810.99; P < .01), and ticagrelor (OR: 1.93; 95% CI: 1.013.73; P = .04) administration. The urinary tract was the most frequent bleeding site, followed by femoral arteries. In conclusion, ticagrelor and tirofiban should be used with caution in elderly ACS patients.

Static Cyclic Fatigue Resistance in Abrupt Curvature, Surface Topography, and Torsional Strength of R-Pilot and ProGlider Glide Path Instruments.

INTRODUCTION: This study aimed to compare ProGlider (Dentsply Sirona, Ballaigues, Switzerland) and R-Pilot (VDW, Munich, Germany) instruments in terms of their cyclic fatigue resistance using an artificial stainless steel canal showing an abrupt apical curvature, torsional resistance according to the ISO specification, and topographic changes on the instrument surface after glide path management in mesial canals of mandibular first molars with the abrupt curvature selected based on their micro-computed tomographic examination. METHODS: Eighty instruments were used: 40 ProGlider (size 0.16, .02v taper) and 40 R-Pilot (size 0.125, .04 taper) instruments. The cyclic fatigue resistance was tested in a static test model using an artificial canal with an abrupt apical curvature (angle of curvature of 90° and radius of curvature of 2 mm). The torsional resistance test was performed according to ISO 3630-1 specifications. To determine surface topography of the unused and used instruments, mesial root canals of mandibular molars with an abrupt apical curvature were selected to prepare a glide path with either the ProGlider or R-Pilot instrument. An optical profilometer and scanning electron microscopy were used to determine the surface properties. Normally distributed torsional and cyclic resistance data were analyzed using the Student t test, whereas quantitative data obtained by the optical profilometer were analyzed with the Kruskal-Wallis H test with a 5% significance threshold. RESULTS: The R-Pilot showed significantly higher cyclic fatigue and torsional resistance than the ProGlider (P < .05). Angular deflection values were similar between instruments (P < .05). Measurements made from the blade area showed that the surface roughness values of the ProGlider were larger. Cutting blade measurements showed that unused instruments had significantly greater roughness values than used ones (P < .05). Although there was a 14% increase between the blade edge radii of the used and unused R-Pilot instruments, this difference was determined as 61% in ProGlider instruments. CONCLUSIONS: The R-Pilot exhibited greater cyclic fatigue strength than the ProGlider when tested in an artificial canal with an inner diameter of 1.0 mm and an abrupt apical curvature. Torsional resistance of the R-Pilot was higher than the ProGlider, but the angular deflection values were similar. Glide path preparation in a mesial root canal with an abrupt apical curvature did not increase the surface roughness of both instruments but resulted in a greater blade edge radius.

The relationship between protein convertase subtilisin kexin type-9 levels and extent of coronary artery disease in patients with non-ST-elevation myocardial infarction.

BACKGROUND: Cardiovascular disease is one of the leading causes of death worldwide. According to the results of various studies, protein convertase subtilisin kexin type-9 (PCSK9) was determined as a novel risk factor for stable coronary artery disease. Few studies have investigated the relationship between PCSK9 levels and the severity of coronary artery disease in patients with acute coronary syndrome; thus, we herein aimed to investigate this relationship in patients with non-ST-elevation myocardial infarction (NSTEMI) who underwent coronary angiography. PATIENTS AND METHODS: Herein, 168 patients with NSTEMI were prospectively enrolled, and severity of atherosclerotic lesions was determined using SYNergy between percutaneous coronary intervention with TAXus and cardiac surgery (SYNTAX), Gensini and Jeopardy scores. Plasma PCSK9 levels, lipid parameters and C-reactive protein levels were measured after a 12-h fasting period. The relationship of PCSK9 levels and clinical and laboratory parameters of patients with their SYNTAX, Gensini and Jeopardy scores was investigated. RESULTS: Pearson correlation analysis showed a strong positive correlation between PCSK9 and the three scores (P < 0.001, r > 0.5 for all). In ROC analysis, a mid-high SYNTAX score of at least 25 was predicted with a sensitivity of 81% and a specificity of 63% when the PCSK9 level was higher than 52.8 ng/ml (area under a curve 0.76, P < 0.001). Multivariate linear regression analysis revealed that PCSK9, low-density lipoprotein cholesterol and creatinine levels were independent predictors of a high SYNTAX score. CONCLUSION: Taken together, high PCSK9 levels may be a risk factor for adverse events in patients with NSTEMI. Aggressive lipid-lowering therapies may benefit this group of patients.

Adaptation and Transfer of Robot Motion Policies for Close Proximity Human-Robot Interaction.

In the context of human-robot collaboration in close proximity, safety and comfort are the two important aspects to achieve joint tasks efficiently. For safety, the robot must be able to avoid dynamic obstacles such as a human arm with high reliability. For comfort, the trajectories and avoidance behavior of the robot need to be predictable to the humans. Moreover, these two aspects might be different from person to person or from one task to another. This work presents a framework to generate predictable motions with dynamic obstacle avoidance for the robot interacting with the human by using policy improvement method. The trajectories are generated using Dynamic Motion Primitives with an additional potential field term that penalizes trajectories that may lead to collisions with obstacles. Furthermore, human movements are predicted using a data-driven approach for proactive avoidance. A cost function is defined which measures different aspects that affect the comfort and predictability of human co-workers (e.g., human response time, joint jerk). This cost function is then minimized during human-robot interaction by the means of policy improvement through black-box optimization to generate robot trajectories that adapt to human preferences and avoid obstacles. User studies are performed to evaluate the trust and comfort of human co-workers when working with the robot. In addition, the studies are also extended to various scenarios and different users to analyze the task transferability. This improves the learning performance when switching to a new task or the robot has to adapt to a different co-worker.

An Inverse Optimal Control Approach to Explain Human Arm Reaching Control Based on Multiple Internal Models.

Human motor control is highly efficient in generating accurate and appropriate motor behavior for a multitude of tasks. This paper examines how kinematic and dynamic properties of the musculoskeletal system are controlled to achieve such efficiency. Even though recent studies have shown that the human motor control relies on multiple models, how the central nervous system (CNS) controls this combination is not fully addressed. In this study, we utilize an Inverse Optimal Control (IOC) framework in order to find the combination of those internal models and how this combination changes for different reaching tasks. We conducted an experiment where participants executed a comprehensive set of free-space reaching motions. The results show that there is a trade-off between kinematics and dynamics based controllers depending on the reaching task. In addition, this trade-off depends on the initial and final arm configurations, which in turn affect the musculoskeletal load to be controlled. Given this insight, we further provide a discomfort metric to demonstrate its influence on the contribution of different inverse internal models. This formulation together with our analysis not only support the multiple internal models (MIMs) hypothesis but also suggest a hierarchical framework for the control of human reaching motions by the CNS.

A Hybrid Framework for Understanding and Predicting Human Reaching Motions.

Robots collaborating naturally with a human partner in a confined workspace need to understand and predict human motions. For understanding, a model-based approach is required as the human motor control system relies on the biomechanical properties to control and execute actions. The model-based control models explain human motions descriptively, which in turn enables predicting and analyzing human movement behaviors. In motor control, reaching motions are framed as an optimization problem. However, different optimality criteria predict disparate motion behavior. Therefore, the inverse problem-finding the optimality criterion from a given arm motion trajectory-is not unique. This paper implements an inverse optimal control (IOC) approach to determine the combination of cost functions that governs a motion execution. The results indicate that reaching motions depend on a trade-off between kinematics and dynamics related cost functions. However, the computational efficiency is not sufficient for online prediction to be utilized for HRI. In order to predict human reaching motions with high efficiency and accuracy, we combine the IOC approach with a probabilistic movement primitives formulation. This hybrid model allows an online-capable prediction while taking into account motor variability and the interpersonal differences. The proposed framework affords a descriptive and a generative model of human reaching motions which can be effectively utilized online for human-in-the-loop robot control and task execution.

Revision shoulder arthroplasty with a reverse shoulder prosthesis : Use of structural allograft for glenoid bone loss.

INTRODUCTION: Revision shoulder arthroplasty presents many unique and complex challenges when glenoid bone loss is involved. A distorted and medialized anatomy prevents the proper mechanics of the reverse prosthesis with regard to deltoid tension and ultimate function. This paper highlights one surgeon's experience using structural allograft for glenoid bone loss. PATIENTS AND METHODS: In all, 20 patients for a total of 24 surgeries with a medialized glenoid and/or substantial glenoid bone loss of grade IIB or higher were evaluated in this retrospective study. The allograft surgeries were performed as a one-stage procedure except for three patients. Recombinant human bone morphogenetic protein-2 (BMP2) was added to supplement incorporation in all cases. Four patients had two separate allograft procedures. Eight of the allograft procedure were femoral shaft, eleven of the allografts were femoral neck/head, and five of the allograft procedures were from proximal humerus. A graft was considered a success if they had at least 12 months of clinical and radiographic follow-up without subsequent removal of the graft or radiographic failure. Patients with less than 12 months of follow-up were included if the graft was removed or had early failure. RESULTS: All femoral shaft allografts except one failed, and during revision surgery it was often noted that the graft was cracked where the peripheral screws had been drilled. In nine patients the graft was still in place at last follow-up, seven of these were femoral neck/head allografts. Five grafts were removed secondary to infection. Average follow-up was 24 months (range 5-45 months). CONCLUSIONS: Femoral neck allografts are an option in patients with substantial bone loss. The authors do not recommend use of femoral shaft allografts.

Regular exercise alleviates renovascular hypertension-induced cardiac/endothelial dysfunction and oxidative injury in rats.

The importance of physical activity in the management of renovascular diseases is well-known, but lacks evidence of underlying mechanisms. The purpose of the study was to elucidate the protective/therapeutic effects of regular exercise on experimental renovascular hypertension (RVH)-induced oxidative stress and cardiac dysfunction. Wistar albino rats underwent a RVH surgery (2K1C, Goldblatt). Three weeks later half of the rats started swimming exercise for 9 weeks (n = 15), while the sedentary RVH group (n = 15) had no exercise during that period. Sham-operated control rats (n = 10), had the similar surgical procedures but the left renal artery was left unclipped. Body weights were monitored, and blood pressures were measured weekly using tail-cuff. Echocardiographic evaluation was performed on the 3(rd) week and on the 12(th) week of the experiment before the rats were decapitated. Heart and thoracic aorta were removed and serum was collected, while aortic samples were put in a 10% formaldehyde solution for immunochemistry. Cardiac tissue samples obtained from each animal were used for the determination of tissue myeloperoxidase (MPO) and catalase (CAT) activities, malondialdehyde (MDA), and glutathione (GSH) levels. In the sedentary RVH group, aortic contractile response (contraction/relaxation in isolated organ bath), left ventricular diastolic and systolic dimensions, and immunohistochemical staining of aortic inducible nitric oxide synthase (iNOS) were increased, while ejection fraction and aortic endothelial nitric oxide synthase (eNOS) staining were decreased. RVH in the sedentary rats resulted in increased pro-inflammatory cytokines (TNF-α, IL-2, IL-6), lipid peroxidation (malondialdehyde) and neutrophil infiltration (myeloperoxidase activity) along with reductions in antioxidant glutathione and catalase levels in the cardiac tissue. Exercise after RVH increased the immunohistochemical staining of aortic eNOS, decreased iNOS staining and reversed the alterations in echocardiographic and oxidative parameters. Regular exercise commenced after RVH surgery alleviated renovascular hypertension-induced oxidative injury, by modulating oxidant-antioxidant balance via the involvement of the endothelial NO system.

Four Separate Hepatic Vein Reconstructions in Living-Donor Right-Lobe Liver Transplantation: Case Report.

Living-donor liver transplantation (LDLT) with the use of a partial liver graft was established as an option to overcome the donor pool shortage, especially in developing countries. When right-lobe grafts are used for LDLT, appropriate venous drainage of the anterior segment is critical for maximizing the graft capacity. Here, we report a successful LDLT case using a right-lobe graft with 4 hepatic veins that were anastomosed separately to obtain adequate blood flow through the vena cava.

The efficacy of an enuresis alarm in monosymptomatic nocturnal enuresis.

INTRODUCTION: Monosymptomatic nocturnal enuresis (MNE) is a frequent problem in children older than five years of age. Of the various treatment options, the enuresis alarm has been widely advocated for treating nocturnal enuresis. This study was designed to evaluate the success rates of the enuretic alarm device in patients with MNE. METHODS: 40 patients who had significant MNE (three or more wet nights per week) were included. They used an enuretic alarm for 12 weeks initially. If a relapse was observed, reusage of the device was provided. A success criterion was defined as "14 consecutive dry nights" and a relapse criterion was "more than one wet night a week". RESULTS: The patients' mean age was 8.1 (range 6-16) years and the mean follow-up time was 10.2 (range 6-19) months. 27 patients became dry at night at the end of three months. In the follow-up period, a relapse was observed in 66.7 percent of the initial responders. For recovery, 14 patients started to reuse the device, and seven of them responded positively. At the end of the treatment, a total of 13 of the patients had benefited from the enuretic alarm. CONCLUSION: During the follow-up, the enuretic alarm device provided acceptable initial and long-term complete dryness in patients with primary nocturnal enuresis. Without the need for expensive pharmacological intervention, the alarm treatment is an effective choice for children with nocturnal enuresis.

Functional assessment of reattached macula in nine cases with excellent Snellen acuities.

PURPOSE: To compare the macular functions of patients with excellent visual acuity after retinal detachment (RD) surgery, with the healthy fellow eye. METHODS: Of 214 patients, nine patients, who were successfully operated because of unilateral RD involving the macula and achieved excellent visual acuity, were analysed. The fellow eyes of the patients were taken as the control group. The macular functions were evaluated with visual acuity, contrast sensitivity, colour vision, visual field, and pattern VEP in operated and nonoperated eyes. RESULTS: There was no significant difference in visual acuity, contrast sensitivity, colour vision, and VEP outcomes between operated and nonoperated eyes. However, it was seen that the mean deviation in the visual field was significantly higher in the operated eyes (5.8+/-1.8 dB) when compared with the undetached fellow eyes (3.1+/-1.8 dB), (t=12.5; P=0.013). CONCLUSION: Even though the visual acuity, colour vision, contrast sensitivity, and VEP results returned to normal after a successful RD surgery, we found that the mean deviation measured by the visual field, which reflects the retinal sensitivity, was still significantly low after nearly 5 years follow-up.

Structure and function of animal cryptochromes.

Cryptochrome (CRY) is a photolyase-like flavoprotein with no DNA-repair activity but with known or presumed blue-light receptor function. Animal CRYs have DNA-binding and autokinase activities, and their flavin cofactor is reduced by photoinduced electron transfer. In Drosophila, CRY is a major circadian photoreceptor, and in mammals, the two CRY proteins are core components of the molecular clock and potential circadian photoreceptors. In mammals, CRYs participate in cell cycle regulation and the cellular response to DNA damage by controlling the expression of some cell cycle genes and by directly interacting with checkpoint proteins.

Vaccination coverage in the South-East Anatolian Project (SEAP) region and factors influencing low coverage.

OBJECTIVES: To determine the vaccination coverage of children living in the South-east Anatolian Project (SEAP) region; whether the vaccination coverage was similar to formal reports, other studies and other countries; and which factors influence vaccination, in order to indicate how vaccination coverage can be improved. STUDY DESIGN: A descriptive cross-sectional study conducted in nine provinces of the SEAP region in order to determine public health problems and their causes. METHODS: A population-based sample of 1150 houses was selected from rural and urban areas of the SEAP region and visited by the researchers. Questionnaires were applied in 2001 and 2002. RESULTS: In the SEAP region, only 30% of children had received a complete set of vaccines. The vaccination coverage was 76.7% for Bacille Calmette-Guérin; 62.0% for the third doses of diphtheria, tetanus toxoid, pertussis and polio vaccine; 62.7% for measles; 44% for the third dose of hepatitis B vaccine in children aged 12-23 months; and 13.3% for the second dose of tetanus toxoid in women who gave birth in the last 5 years. In logistic regression analysis, residence type, number of siblings, birth interval, follow-up visits of midwives, and maternal level of education were found to influence whether children were completely vaccinated. CONCLUSIONS: The findings of this study indicate that vaccination coverage is not acceptable in the SEAP region. Efforts must focus on family planning services, education of women, follow-up visits and strengthening health facilities, especially in rural regions, to improve vaccination.

Family planning in the Southeast Anatolian Project Region.

OBJECTIVES: The aim of this study was to evaluate contraceptive use by women of reproductive age in the Southeast Anatolian Project Region and the promotion of the use of family planning services. METHODS: An optimum sample size to represent the rural and urban area of the region was determined and the sample was chosen by sampling method proportional to the size. A total of 1126 houses were visited and questions about reproductive health were asked of 1019 ever-married (currently married, widows and divorced) women. RESULTS: The study showed that 48.2% of the ever-married women of reproductive age had never used any method of family planning; 37.4% were currently using a family planning method, and 14.4% had used a family planning method in the past. Of the women who were currently using a family planning method, 73.1% were using an effective method. The result of the logistic regression analysis showed that educational level, knowledge of Turkish, type of residence, and total number of living children were the main variables that affected the use of family planning methods. CONCLUSIONS: Use of family planning methods in the region was not at the expected level. In order to decrease the barriers to family planning in developing countries, we must provide obtainable, acceptable, integrated health services.

Risk factors for postoperative respiratory complications in adult liver transplant recipients.

To determine the types and the incidence of as well as risk factors for early postoperative (<30 days) respiratory complications in adult liver transplant (LT) recipients, we reviewed The data of 44 consecutive adult LT recipients who received their grafts from January 1995 through December 2002. The data included demographic features; primary diagnosis; number of intraoperative transfusions; preoperative and postoperative laboratory values; intraoperative and postoperative characteristics; and early postoperative (<30 days) mortality. Pulmonary atelectasis, pleural effusion, pneumonia, respiratory failure, and pulmonary edema were the respiratory complications investigated. Twenty-six patients (59.1%) developed at least one respiratory complication during the early postoperative period. The most frequent complication was pleural effusion (n = 18, 40.9%), followed by atelectasis (n = 13, 29.5%), pneumonia (n = 10, 22.7%), acute respiratory failure (n = 5, 11.4%), pulmonary edema (n = 3, 6.8%), and pneumothorax (n = 2, 4.5%). Compared to the patients who did not develop these problems, the affected cohort was significantly older (27 +/- 12 years vs 36 +/- 14 years, respectively; P =.039) and required more intraoperative transfusions (P =.005). Among the overall mortality rate of 15.9%, patients who developed pneumonia showed a significantly higher mortality (40.0% vs 8.8%, respectively; P =.037). Pleural effusion, atelectasis, and pneumonia are the main respriatory complications that occur in adult LT recipients. Patient age and intraoperative transfusion requirements are important predictors of early postoperative complications. Pneumonia is associated with a poor prognosis in this patient group.

The effects of family planning education provided to different gender groups.

OBJECTIVE: To determine whether women or men should be preferred as the target group of the family planning education. DESIGN: Community trial (educational intervention study). SETTING: Three villages having similar characteristics in Gaziantep, Turkey. POPULATION: Currently married women aged between 15-49 and their husbands in these villages. METHODS: Family planning education was given only to women in the first village, only to men in the second village and to both women and their husbands in the third village. MAIN OUTCOME MEASURES: Changes in knowledge, attitudes, the behaviour of married women and their husbands between surveys performed before and after family planning education. RESULTS: Important changes in knowledge, attitudes, and behaviour were determined in all intervention groups after family planning education. The rate of effective contraceptive usage among women using any one of the contraceptive methods described significantly increased in all groups, especially where family planning education was given to both sexes. CONCLUSIONS: Family planning education given to one of the couples may easily affect the other. Consistent and regular education is more important than selecting target gender groups for family planning education.

A healthy birth after intracytoplasmic sperm injection by using immotile testicular spermatozoa in a case with totally immotile ejaculated spermatozoa before and after Percoll gradients.

Total asthenozoospermia is a severe problem, as only a micromanipulation technique can assist the couple, and even then fertilization and pregnancy rates are very low. The first healthy birth, achieved by using testicular immotile spermatozoa in a case with total asthenozoospermia before and after Percoll gradient preparation, is reported.