Zap Q-Learning for Optimal Stopping Time Problems

The objective in this paper is to obtain fast converging reinforcement learning algorithms to approximate solutions to the problem of discounted cost optimal stopping in an irreducible, uniformly ergodic Markov chain, evolving on a compact subset of $\mathbb{R}^n$. We build on the dynamic programming approach taken by Tsitsikilis and Van Roy, wherein they propose a Q-learning algorithm to estimate the optimal state-action value function, which then defines an optimal stopping rule. We provide insights as to why the convergence rate of this algorithm can be slow, and propose a fast-converging alternative, the "Zap-Q-learning" algorithm, designed to achieve optimal rate of convergence. For the first time, we prove the convergence of the Zap-Q-learning algorithm under the assumption of linear function approximation setting. We use ODE analysis for the proof, and the optimal asymptotic variance property of the algorithm is reflected via fast convergence in a finance example

Augmenting Neural Nets with Symbolic Synthesis: Applications to Few-Shot Learning

We propose symbolic learning as extensions to standard inductive learning models such as neural nets as a means to solve few shot learning problems. We device a class of visual discrimination puzzles that calls for recognizing objects and object relationships as well learning higher-level concepts from very few images. We propose a two-phase learning framework that combines models learned from large data sets using neural nets and symbolic first-order logic formulas learned from a few shot learning instance. We develop first-order logic synthesis techniques for discriminating images by using symbolic search and logic constraint solvers. By augmenting neural nets with them, we develop and evaluate a tool that can solve few shot visual discrimination puzzles with interpretable concepts

Unusual Radiographic Presentation of Pneumocystis Pneumonia in a Patient with AIDS.

Pneumocystis jirovecii pneumonia (PCP) typically presents as an interstitial and alveolar process with ground glass opacities on chest computed tomography (CT). The absence of ground glass opacities on chest CT is thought to have a high negative predictive value for PCP in individuals with AIDS. Here, we report a case of PCP in a man with AIDS who presented to our hospital with subacute shortness of breath and a nonproductive cough. While his chest CT revealed diffuse nodular rather than ground glass opacities, bronchoscopy with bronchoalveolar lavage and transbronchial biopsies confirmed the diagnosis of PCP and did not identify additional pathogens. PCP was not the expected diagnosis based on chest CT, but it otherwise fit well with the patient's clinical and laboratory presentation. In the era of combination antiretroviral therapy, routine prophylaxis for PCP, and increased use of computed tomography, it may be that PCP will increasingly present with nonclassical chest radiographic patterns. Clinicians should be aware of this presentation when selecting diagnostic and management strategies

Aktivitas Antioksidan Dari Ekstrak Tongkol Jagung (Zea Mays L.)

The objective of this research was to determine the potential antioxidant phytochemicalextracts corn cob (Zea mays L.). Corn cobs extracted using maceration method for 1x24 hours.Determination of phytochemical content is done by calculating the total phenolic. Testingantioxidant activity using free-radical scavengers DPPH (1,1-diphenyl-2-pikrilhidrazil). Results ofthis research showed that the extract of corn cobs have total phenolic. Extract 60% corn cobs haveprophylactic activity of free radicals, followed by extract 40, 80 and 20%. Conclusion of thisresearch is corn cob extracts have potential as antioxidants phytochemicals

A prospective study of effect of amniotic fluid index less than 5 at term on perinatal outcome

Background: To study the effect of oligohydramnios in pregnancy and its value in predicting adverse perinatal outcome.Methods: A prospective case control study of pregnancy outcome in 100 cases with ultrasound diagnosis of oligohydramnios at term compared with 100 controls with no oligohydramnios. The study was done over a period of 3 years at SSMC Tumkur, India.Results: Oligohydramnios at term is associated with poor perinatal outcome. Significant increase in abnormal foetal heart rate, meconium stained liquor, delivery by cesarean section, low Apgar intrauterine growth restriction (IUGR), increased admissions to  neonatal intensive-care unit (NICU) were seen in study group, however perinatal mortality was more in study group but not statistically significant (P=0.31)Conclusions: AFI <5 at term is an important fetal surveillance methods to identify poor perinatal outcome and thereby makes possible intervention so as to reduce perinatal morbidity and mortality