A Cubic-regularized Policy Newton Algorithm for Reinforcement Learning

We consider the problem of control in the setting of reinforcement learning (RL), where model information is not available. Policy gradient algorithms are a popular solution approach for this problem and are usually shown to converge to a stationary point of the value function. In this paper, we propose two policy Newton algorithms that incorporate cubic regularization. Both algorithms employ the likelihood ratio method to form estimates of the gradient and Hessian of the value function using sample trajectories. The first algorithm requires an exact solution of the cubic regularized problem in each iteration, while the second algorithm employs an efficient gradient descent-based approximation to the cubic regularized problem. We establish convergence of our proposed algorithms to a second-order stationary point (SOSP) of the value function, which results in the avoidance of traps in the form of saddle points. In particular, the sample complexity of our algorithms to find an $\epsilon$-SOSP is $O(\epsilon^{-3.5})$, which is an improvement over the state-of-the-art sample complexity of $O(\epsilon^{-4.5})$

Neutrinos from the Sun can discover dark matter-electron scattering

We probe dark matter-electron scattering using high-energy neutrino observations from the Sun. Dark matter (DM) interacting with electrons can get captured inside the Sun. These captured DM may annihilate to produce different Standard Model (SM) particles. Neutrinos produced from these SM states can be observed in IceCube and DeepCore. Although there is no excess of neutrinos from the Solar direction, we find that the current data-sets of IceCube and DeepCore set the strongest constraint on DM-electron scattering cross section in the DM mass range $10\,$GeV to $10^5\,$GeV. Our work implies that future observations of the Sun by neutrino telescopes have the potential to discover DM-electron interaction.Comment: 11 pages, 5 figures. Comments are welcom

Enhancement of quality parameters and shelf-life of papaya fruit (Carica papaya L.) by edible coating during storage and transportation

The postharvest losses of papaya fruits are important concerns during storage, shipping and marketing; the causes of these postharvest losses include microbial infestation, temperature, inappropriate handling and other factors. Which can be decreased by using edible coatings that have enhanced quality and have a longer shelf life. The effects of three different coating materials-aloe vera gel, ascorbic acid and chitosan on the shelf life and qualitative parameters of papaya fruits that were maintained at room temperature for a period of 15 days were investigated. When compared to fruits that have not been coated, fruits that have been coated with aloe vera gel, ascorbic acid and chitosan retain the original values for all of the qualitative parameters, including total soluble solids (9.9), titratable acidity (0.670 %), ascorbic acid (67.125 100 g/mg), TSS: acid ratio (23.116 percent), total sugar (0.119 %), reducing sugar (24.570 %) and non-reducing. According to the findings of this investigation, the combination of aloe vera gel (50%), chitosan (1%) and ascorbic acid (1%) has the potential to lengthen the shelf life of papaya fruits while maintaining their nutritional qualities, which is significant for the purposes of commercial storage, transportation and sales

Application of natural preservatives and sweeteners in fruit products to reduce health risks - a review

The costs of food deterioration in terms of both money and health are rising. Fungi, bacteria, yeast, insects, and rodent contamination of food supplies continue to be a major public health concern. Chemical preservatives are effective but can be potentially fatal to human health in certain cases. As potent food preservatives, essential oils made from plants are a great alternative to synthetic preservatives. They also possess a variety of anti-inflammatory, antibacterial, and antioxidant effects. The use of artificial sweeteners in food products, which raises safety questions and health issues while also having reduced nutritional value, is another problem in the food industry. Because natural sweeteners are linked to a healthy lifestyle and have superior nutritional qualities, consumers today prefer them. This article goes through the issues with artificial sweeteners and preservatives and goes into great length about the many different essential oils and natural sweeteners that are much safer and healthier alternatives

Enhanced frequency upconversion in Ho3+/Yb3+/Li+:YMoO4 nanophosphors for photonic and security ink applications

The YMoO4 nanophosphors codoped with Ho3+/Yb3+/Li+ ions synthesized by the chemical coprecipitation method have been structurally characterized by using X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), and Transmission Electron Microscopy (TEM) techniques. The TEM bright field imaging shows that the developed nanophosphors are crystalline in nature with particle size similar to 45 nm. The upconversion (UC) emission spectra upon excitation at 980 nm of the nanophosphors at low pump power (<900 mW) show the emission peaks in the UV, green, and red regions, whereas at high pump power (>= 900 mW) an intense broad band ranging from 400-900 nm along with a UV band has been observed. The enhancement of about similar to 104 times corresponding to the green band in the Ho3+-Yb3+-Li+ codoped nanophosphors compared to that of the Ho3+ singly doped nanophosphors has been observed. This enhancement is caused by the energy transfer from the Yb3+ to Ho3+ ions and modified the local crystal field developed around the rare earth ions. A higher value of the slope (i.e., n similar to 6.38) for broad band emission within the 944 mW-1200 mW pump power region in the Ho3+-Yb3+-Li+ codoped nanophosphors is found to be due to the involvement of the photon avalanche population process but it is not related to the black body radiation. The intense peak at similar to 564 nm and similar to 648 nm for the broad band emission is attributed to the charge transfer luminescence of codoped nanophosphors, which is related to the oxygen ion present in the MoO4 group and Yb3+ ion. The observations described in this paper may be of significant interest for developing the visible upconverters, security ink, and novel devices for displays in the low and high pump power region. Published by AIP Publishing

Preparation of ultrafine CsCl crystallites by combined cryogenic and room temperature ball milling

The present investigation reports the preparation and microstructural characterization of ultrafine CsCl crystallites using combined cryogenic and room temperature (RT) mechanical milling. The milling has been performed in evacuated WC vials under high purity argon atmosphere. The low temperature milling has been utilized as an effective means of rapid fracturing of the CsCl crystallites. This was followed by RT milling for different time durations. The final crystallite size obtained is 10 +/- 6 nm for sample cryo-milled for 11 h and subsequently RT milled for 35 h. The experimental findings indicate the strong effect of duration of cryo-milling on the final size of the crystallites. The prolonged room temperature milling leads to increase of the crystallite size due to deformation-induced sintering. The results have been discussed in the light of currently available literature. (C) 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved