Information-Theoretic Stochastic Optimal Control via Incremental Sampling-based Algorithms

This paper considers optimal control of dynamical systems which are represented by nonlinear stochastic differential equations. It is well-known that the optimal control policy for this problem can be obtained as a function of a value function that satisfies a nonlinear partial differential equation, namely, the Hamilton-Jacobi-Bellman equation. This nonlinear PDE must be solved backwards in time, and this computation is intractable for large scale systems. Under certain assumptions, and after applying a logarithmic transformation, an alternative characterization of the optimal policy can be given in terms of a path integral. Path Integral (PI) based control methods have recently been shown to provide elegant solutions to a broad class of stochastic optimal control problems. One of the implementation challenges with this formalism is the computation of the expectation of a cost functional over the trajectories of the unforced dynamics. Computing such expectation over trajectories that are sampled uniformly may induce numerical instabilities due to the exponentiation of the cost. Therefore, sampling of low-cost trajectories is essential for the practical implementation of PI-based methods. In this paper, we use incremental sampling-based algorithms to sample useful trajectories from the unforced system dynamics, and make a novel connection between Rapidly-exploring Random Trees (RRTs) and information-theoretic stochastic optimal control. We show the results from the numerical implementation of the proposed approach to several examples.Comment: 18 page

Machine learning and dynamic programming algorithms for motion planning and control

Robot motion planning is one of the central problems in robotics, and has received considerable amount of attention not only from roboticists but also from the control and artificial intelligence (AI) communities. Despite the different types of applications and physical properties of robotic systems, many high-level tasks of autonomous systems can be decomposed into subtasks which require point-to-point navigation while avoiding infeasible regions due to the obstacles in the workspace. This dissertation aims at developing a new class of sampling-based motion planning algorithms that are fast, efficient and asymptotically optimal by employing ideas from Machine Learning (ML) and Dynamic Programming (DP). First, we interpret the robot motion planning problem as a form of a machine learning problem since the underlying search space is not known a priori, and utilize random geometric graphs to compute consistent discretizations of the underlying continuous search space. Then, we integrate existing DP algorithms and ML algorithms to the framework of sampling-based algorithms for better exploitation and exploration, respectively. We introduce a novel sampling-based algorithm, called RRT#, that improves upon the well-known RRT* algorithm by leveraging value and policy iteration methods as new information is collected. The proposed algorithms yield provable guarantees on correctness, completeness and asymptotic optimality. We also develop an adaptive sampling strategy by considering exploration as a classification (or regression) problem, and use online machine learning algorithms to learn the relevant region of a query, i.e., the region that contains the optimal solution, without significant computational overhead. We then extend the application of sampling-based algorithms to a class of stochastic optimal control problems and problems with differential constraints. Specifically, we introduce the Path Integral - RRT algorithm, for solving optimal control of stochastic systems and the CL-RRT# algorithm that uses closed-loop prediction for trajectory generation for differential systems. One of the key benefits of CL-RRT# is that for many systems, given a low-level tracking controller, it is easier to handle differential constraints, so complex steering procedures are not needed, unlike most existing kinodynamic sampling-based algorithms. Implementation results of sampling-based planners for route planning of a full-scale autonomous helicopter under the Autonomous Aerial Cargo/Utility System Program (AACUS) program are provided.Ph.D

Carbonic anhydrase inhibitors. Inhibition of red blood cell ostrich (Struthio camelus) carbonic anhydrase with a series of aromatic and heterocyclic sulfonamides.

The purification of red blood cell carbonic anhydrase (CA, EC 4.2. 1. 1) from ostrich (scCA) blood is reported, as well as an inhibition study of this enzyme with a series of aromatic and heterocylic sulfonamides. The ostrich enzyme showed a high activity, comparable to that of the human isozyme II, with k(cat) of 1. 2 center dot 10(6) s(-1) and k(cat)/K-M of 1. 8 center dot 10(7)M(-1) s(-1), and an inhibition profile quite different from that of the human red blood cell cytosolic isozymes hCA I and II. scCA has generally a lower affinity for sulfonamide inhibitors as compared to hCA I and II. The only sulfonamide which behaved as a very potent inhibitor of this enzyme was ethoxzolamide (K-1 = 3.9 nM) whereas acetazolamide and sulfanilamide behaved as weaker inhibitors (inhibition constants in the range 303-570 nM). Several other aromatic and heterocyclic sulfonamides, mostly derivatives of sulfanilamide, homosulfanilamide, 4-aminoethylbenzenesulfonamide or 5-amino-1,3,4-thiadiazole-2-sulfonamide, showed good affinities for the ostrich enzyme, with K-1 values in the range 25 - 72 nM

Warfarin treatment in stent thrombosis

AbstractA 62year-old male patient was admitted to the hospital due to anterior ST segment elevated myocardial infarction. Thrombotic complication developed three times during the hospitalization after primary percutaneous coronary intervention (PCI). Instent thrombus was identified despite the optimal medical therapy, new antiplatelet agents and intravascular ultrasound guided PCI. Therefore, symptoms were controlled with warfarin+clopidogrel treatment. At the third month of warfarin+clopidogrel treatment, the patient was asymptomatic and no active electrocardiographic changes were observed. Stent thrombosis developing under new antiplatelet agents constitutes a great problem and there are no clear data for the solution. We described an interesting case in which we achieved symptomatic control by warfarin+clopidogrel in the stent thrombosis developing during the treatment with dual antiplatelet therapy

Factors associated with postoperative chronic pain and recurrence after laparoscopic total extraperitoneal inguinal hernia repair

Objective: To assess the risk factors for chronic pain and recurrence after laparoscopic total extraperitoneal (TEP) inguinal hernia repair. Methods: Data of the patients who underwent laparoscopic TEP repair were analyzed. Clinical and surgical characteristics, including learning curve, mesh weight, the pore size of the mesh, use of mesh fixation, and fixation methods, were assessed. Fixation by absorbable or nonabsorbable tackers was performed in all procedures except for self-fixating meshes. Mesh brands were tiered into groups regarding pore size and weight. Operative time was defined as the duration between skin incision and dressing. The minimum follow-up was 24 months. Postoperative chronic pain was defined as moderate to severe groin pain, which was accepted as a Visual Analog score ≥3 longer than three months. Pain and recurrence were evaluated at 1 and 6 weeks in clinic visits and at 3, 12, and 24 months by telephone questionnaires. The occurrence of a fascial defect in physical examination or ultrasound was defined as recurrence. Results: Three-hundred and eighty-two procedures were included. Postoperative chronic pain was seen in 31 (8.1%) patients and was higher with micropore mesh (p=0.004), mesh fixation (p=0.002), fixation with titanium tacks (p<0.001) and at first 50 cases (p=0.043). Fifteen (3.9%) patients had a recurrence. Older age (p=0.046), prolonged operative time (p=0.040), body mass index (BMI) (p=0.008) and learning curve (p=0.034) were significantly associated with higher recurrence rate. In multivariate analysis pore size [Odds ratio (OR): 2.911, 95% confidence interval (CI): 1.153-7.351, p=0.024] and fixation with titanium tacks (OR: 8.776, 95% CI: 4.040-14.893, p=0.004) were independent risk factors for chronic pain; BMI (OR: 1.307-95% CI:1.138-1.501, p<0.001) was the only independent risk factor for recurrence. Conclusion: The outcome of laparoscopic TEP repair is related to the technic as well as patient-based factors. Titanium tacks and micropore meshes increase postoperative pain risk without any benefit on recurrence. Patients with higher BMI have an increased recurrence risk

Comparison of opinions of students in tourism field with pre-bachelor’s degree education before and after training (Afyon Kocatepe University sample)

Bu araştırmanın amacı turizm alanında önlisans eğitimi alan öğrencilerin, staj öncesi ve sonrası görüşlerinin karşılaştırılmasıdır. Araştırmada veri toplama yöntemi olarak anket tekniğinden faydalanılmış olup, oluşturulan anket, staja gitmeden ve stajdan döndükten sonra olmak üzere, Afyon Kocatepe Üniversitesi’ne bağlı Meslek Yüksekokulları’nın turizm ile ilgili programlarında okuyan toplam 177 öğrenciye uygulanmıştır. Elde edilen verilerin çözümlenmesinde, ilişkili ölçümler için t testi, bağımsız örneklemler için t testi, Anova, ve Tukey testlerinden faydalanılmıştır. Gerçekleştirilen istatistiksel analizler, öğrencilerin turizm işletmelerinde yapmış oldukları stajları değerlendirmelerine ilişkin; staj öncesi ve sonrası görüşleri arasında anlamlı farklılıklar olduğunu ortaya koymuştur. Buna göre, öğrencilerin staja ilişkin görüşleri, stajdan döndükten sonra olumsuzlaşmaktadır. Ayrıca, öğrencilerin turizm işletmelerinde yapmış oldukları stajları değerlendirmelerine ilişkin; staj öncesi ve sonrası görüşleri bazı demografik özelliklerine göre de farklılıklar göstermiştir.In order to compare the opinions before and after training of students with pre-bachelor’s degree in the tourism filed, as data collecting method in this study questionnaire technique was used. A questionnaire prepared by researcher was prepared and applied to total 177 students of connected Vocational Schools of Ayfon Kocatepe University before and after training period. For analyzing the obtained data’s, for regarded estimation the t test and for individual sampling the t, Anova and Turkey tests were used. According to the performed statistic analyzes about the students estimation of the Touristic Establishments where they had performed their trainings, it is found out that they are meaningful differences in their opinions before and after the performed trainings. Regarding to this issue the students opinions are changing negatively after the performed training. Also, regarding the evaluation of the trainings that students had performed in Touristic Establishments, their opinions before and after the training have shown differences according to some demographic qualifications

Use of Aspergillus niger in the bioleaching of colemanite for the production of boric acid

Colemanite is one of the most important underground riches of Turkey, having approximately 60% of the world boron deposits, and it has a large portion in the deposits. In this study, chemical leaching and biological leaching methods were used for production of boric acid from colemanite (2CaO \ub7 3B3O3 \ub7 5H2O) (Emet-K\ufctahya, Turkey). Oxalic acid concentration, temperature, stirring time and solid-to-liquid ratio were taken as parameters in the chemical leaching process. It was found that the dissolution rate increases with increasing oxalic acid concentration and temperature but it decreases at higher solid-to-liquid ratios in the chemical leaching process. Using optimum conditions (d100 = 0.075 mm; 5% solids by weight; 0.55 M oxalic acid; 80 \ub1 2\ubaC leaching temperature; 150 rpm stirring speed; 90 min leaching time) for colemanite sample (28.05% B2O3) on chemical leaching with oxalic acid experiments, the calculated boric acid extraction efficiency from colemanite ore was 97.89%. Optimum conditions on bioleaching of Emet-K\ufctahya, Turkey colemanite ores using the fungus Aspergillus niger were found to be as follows: reaction temperature 25 \ub1 2oC; solid-to-liquid ratio 5% solids by weight; d100 = 0.075 mm; stirring speed 150 rpm; initial the fungus populations in the inocula about 3 x 107 cells/ml and reaction time 21 days. The calculated boric acid extraction efficiency from colemanite ore was 90.18% under the optimum conditions. Bioleachate contained 12.95 g/l B2O3, 6.60 g/l Ca and 0.087 g/l Mg. Compared with chemical leaching at 5% pulp density, the fungus was less efficient in the extraction of B2O3 from colemanite but the difference in the extraction yields between the two processes was less than 10%. Although bioleaching generally requires a longer period of operation compared to chemical leaching, these results suggest that bioleaching by A. niger may be an alternative or adjunct to conventional physicochemical treatment processes of colemanite to produce boric acid

İnsülinoma Tanı Ve Tedavisinde Endoskopik Ve İntraoperatif Ultrasonografinin Birlikte Kullanımının Önemi

Introduction: Insulinoma is a usually benign tumor of pancreas. It is seen rarely and incidence of insulinoma is 1 in 250,000 patient-years. We present a rare case with insulinoma which well diagnosed and treated with aid of endoscopic and intraoperative ultrasonography. Case Report: A patient involving a 39-year-old woman with complaints of cold sweats, weakness, syncope attacks, palpitations was evaluated in polyclinic. She was hospitalized with the diagnosis of pancreatic insulinoma after abdominal computer tomography(CT), magnetic resonance imaging(MRI) endoscopic ultrasonography(EUS), and biochemical parameters. The patient was well treated with enucleation and after imaging aid of endoscopic and intraoperative ultrasound(IOUS). Discussion: In patients with insulinoma, preoperative localization of tumor is most important for diagnosis and treatment. Therefore; CT scanning, MRI, EUS and SPECT / CT are used for diagnosis of insulinoma. Together use of endoscopic and intraoperatively ultrasonography are increasing recently. Enucleation is a curative treatment approach in insulinoma. Conclusion: Together using of preoperative endoscopic and intraoperative ultrasound is quite helpful in the diagnosis and treatment of insulinoma.Giriş: İnsülinoma pankreasın genellikle benign tümörüdür. Yıllık insidansı 250.000’de 1’dir ve nadir görülmektedir. Tanı ve lokalizasyon amaçlı olarak endoskopik ve intraoperatif ultrasonografinin kullanıldığı ve başarılı bir şekilde tedavi edilen insülinomalı hasta sunuldu. Olgu Sunumu: 39 yaşında bayan hasta uzun süre aç kalması sonucu artan, soğuk terleme, halsizlik, bayılma ve çarpıntı şikâyetleriyle poliklinikte değerlendirildi. Batın bilgisayarlı tomografi(BT), manyetik rezonans görüntüleme(MRG), endoskopik ultrasonografi(EUS) ve biyokimyasal parametrelerden sonra hasta insülinoma tanısıyla yatırıldı. Hastaya EUS ve intraoperatifUSG(IOUS) yardımıyla enüklüasyon yapıldı. Tartışma: İnsülinomalı hastalarda ameliyat öncesi kitlenin lokalizasyonu çok önemlidir. Bu yüzden BT tarama, MRG, EUS ve SPECT/BT tanı amaçlı olarak kullanılmaktadır. Son zamanlarda EUS ve IOUS’un birlikte kullanımı artmaktadır. Insülinomada küratif tedavi yöntemi enükleasyondur. Sonuç: İnsülinoma’nın tanı ve tedavisinde, endoskopik ve intraoperatif ultrasonografinin birlikte kullanımı oldukça yararlıdır

İlaç Bileşimlerinde İslam İnancına Göre Haram Olan Maddelerin Bulunma Durumu

The demandfor halal products by Muslim communities in Islamic and in foreign countrieshave been dealt with by civil society organizations. Moreover, initiatives havebeen made to convey this demand to official institutions. These initiativeshave led to the recognition by official authorities of the rights of muslimsand members of other religions to access health products that meet theirdefinition. The haram issue of drugs is mainly based on the use ofanimal-derived tissues and non-halal components interfered with the productionprocess. Substances derived from animals are used, directly or after treatment,in medicines and vaccines of various pharmaceutical forms, such as tablets,capsules, creams, and injectable solutions. These products can be activesubstances of the drug as well as adjuvants. Nowadays, it is possible toproduce active substances, adjuvants and excipients from alternative sources.Therefore, the necessity of the relevant authorities to ensure that Muslims arenot irrelevant to the demand for halal products and to establish the necessarylegal basis can be considered at least a human rights phenomenon. However,since the survival of people is a priority, it is a valid approach to use theproducts in which the alternative option is not available.İslamülkelerindeki ve ecnebi ülkelerdeki Müslüman toplulukların helal ürün taleplerisivil toplum kuruluşlarında önemle ele alınmış ve resmi kuruluşlar nezdindegirişimlerde bulunulmuştur. Yapılan girişimler resmi otoritelerin, Müslümanlarve diğer din mensupları için kendi tanımlarına uygun (helal) sağlık ürünlerineulaşma hakkını tanımasını sağlamıştır. İlaçlardaki haramlık meselesi, dahaziyade hayvansal dokuların üretimde kullanılmasına dayanmaktadır. Hayvanlardanelde edilen maddeler doğrudan veya işleme tabi tutulduktan sonra tablet,kapsül, krem, enjeksiyonluk çözeltiler gibi çeşitli farmasötik şekillerde, ilaçve aşılarda kullanılmaktadır. Bu ürünler ilacın etkin maddesi olabildiği gibiyardımcı maddeler de olabilmektedir. Günümüzde ilaç etkin ve yardımcımaddelerin alternatif kaynaklardan üretilmesi mümkündür. Dolayısıyla konuylailgili resmi otoritelerin Müslümanların helal ürün taleplerine kayıtsızkalmaması ve gerekli yasal zeminin oluşturulmasını sağlaması gerekliliği enazından bir insan hakları olgusu olarak değerlendirilebilir. Bununla birlikteinsanın yaşatılması öncelikli olduğundan, alternatif seçeneğin bulunmadığıürünlerin tedavide kullanılmaları geçerli bir yaklaşımdır.