The Computational Power of Optimization in Online Learning

We consider the fundamental problem of prediction with expert advice where the experts are "optimizable": there is a black-box optimization oracle that can be used to compute, in constant time, the leading expert in retrospect at any point in time. In this setting, we give a novel online algorithm that attains vanishing regret with respect to $N$ experts in total $\widetilde{O}(\sqrt{N})$ computation time. We also give a lower bound showing that this running time cannot be improved (up to log factors) in the oracle model, thereby exhibiting a quadratic speedup as compared to the standard, oracle-free setting where the required time for vanishing regret is $\widetilde{\Theta}(N)$. These results demonstrate an exponential gap between the power of optimization in online learning and its power in statistical learning: in the latter, an optimization oracle---i.e., an efficient empirical risk minimizer---allows to learn a finite hypothesis class of size $N$ in time $O(\log{N})$. We also study the implications of our results to learning in repeated zero-sum games, in a setting where the players have access to oracles that compute, in constant time, their best-response to any mixed strategy of their opponent. We show that the runtime required for approximating the minimax value of the game in this setting is $\widetilde{\Theta}(\sqrt{N})$, yielding again a quadratic improvement upon the oracle-free setting, where $\widetilde{\Theta}(N)$ is known to be tight

Studi Aplikasi Keramik Znbico Sebagai Termistor Ntc

STUDY ON THE APPLICA TION OF ZnBiCo CERAMICS AS NTC THERMISTORS. A study onthe application ofZnO-Bi203-CoO (ZnBiCo) ceramicsfor NTC thermistors had been carried out. The aim ofthisstudywas tofind alternative NTCthermistors. The studywas done as follow. Powder ofZnO, CoO andBi203 with concentration of Bi203 of 0, 0.25, 0.5, and 0.75 mole % and of CoO of 2 mole % werehomogeneously mixed. The mixedpowder was pressed with pressure of3.9ton/cm2 into pellets and sinteredat HOCfC in airfor 1 hour. The sintered pellets were evaluated using x-ray diffraction (XRD), opticalmicroscope andSEM(Scanningelectron microscope). Resistivity-temperature characteristic (p-Tcurve) wasdetermined through measurement of resistivity at various temperatures from room temperature to WCfC.XRD andmicrostructure datashowed thatmostofCoOformed a solid solution withZnOmatrix while Bi203was segregated at grain boundaries as ZnO,24Bi203 second phase. It was known that the all ceramicsproducedin this studyhad the same structure i.e. hexagonal. It was known also that the addition ofBi203increased the average grain size of the ZnBiCo ceramics. Electrical data showed that Bi203 increased theroom temperature resistivity (ps^) and the thermistor constant (B) of the ZnBiCo ceramic thermistors. Thethermistor constant and sensitivity (a) of the thermistor ceramics in this study were relatively high (largerthan 200(fKfor Band larger than 2.2 (°K)~lfor a)andsuitableforcommercial application

Equidistribution of expanding translates of curves and Dirichlet's theorem on Diophantine approximation

We show that for almost all points on any analytic curve on R^{k} which is not contained in a proper affine subspace, the Dirichlet's theorem on simultaneous approximation, as well as its dual result for simultaneous approximation of linear forms, cannot be improved. The result is obtained by proving asymptotic equidistribution of evolution of a curve on a strongly unstable leaf under certain partially hyperbolic flow on the space of unimodular lattices in R^{k+1}. The proof involves ergodic properties of unipotent flows on homogeneous spaces.Comment: 26 page

Interaction Between Active Compounds From Aegle Marmelos Correa as Anti Inflammation Agent with Cox-1 and Cox-2 Receptor

The compounds in Aegle marmelos have an activity as anti inflammation. The objective of this study is to evaluate six active compounds in Aegle marmelos Correa, (E,R)- Marmin, skimmianine, (S)-aegeline, aurapten, zeorin, and dustanin as anti inflammation to the COX-1 and COX-2 as target receptors. Method: Molecular docking was done with PLANTS. Ligand preparation used MarvinSketch, and protein preparation was done by using YASARA. The result was marmin, skimmianine, aegeline, aurapten, zeorin, and dustanin have interaction with Arg120, tyr 355, and Ile 523 in COX-1 and Ser353, Arg 513, and Ser 530 in COX-2. Based on the result of molecular docking, active compounds in Aegle marmelos Correa have potency as anti inflammation agent

Discovering Valuable Items from Massive Data

Suppose there is a large collection of items, each with an associated cost and an inherent utility that is revealed only once we commit to selecting it. Given a budget on the cumulative cost of the selected items, how can we pick a subset of maximal value? This task generalizes several important problems such as multi-arm bandits, active search and the knapsack problem. We present an algorithm, GP-Select, which utilizes prior knowledge about similarity be- tween items, expressed as a kernel function. GP-Select uses Gaussian process prediction to balance exploration (estimating the unknown value of items) and exploitation (selecting items of high value). We extend GP-Select to be able to discover sets that simultaneously have high utility and are diverse. Our preference for diversity can be specified as an arbitrary monotone submodular function that quantifies the diminishing returns obtained when selecting similar items. Furthermore, we exploit the structure of the model updates to achieve an order of magnitude (up to 40X) speedup in our experiments without resorting to approximations. We provide strong guarantees on the performance of GP-Select and apply it to three real-world case studies of industrial relevance: (1) Refreshing a repository of prices in a Global Distribution System for the travel industry, (2) Identifying diverse, binding-affine peptides in a vaccine de- sign task and (3) Maximizing clicks in a web-scale recommender system by recommending items to users

Delirium, frailty and mortality:interactions in a prospective study of hospitalized older people

AbstractBackgroundIt is unknown if the association between delirium and mortality is consistent for individuals across the whole range of health states. A bimodal relationship has been proposed, where delirium is particularly adverse for those with underlying frailty, but may have a smaller effect (perhaps even protective) if it is an early indicator of acute illness in fitter people. We investigated the impact of delirium on mortality in a cohort simultaneously evaluated for frailty.MethodsWe undertook an exploratory analysis of a cohort of consecutive acute medical admissions aged ≥70. Delirium on admission was ascertained by psychiatrists. A Frailty Index (FI) was derived according to a standard approach. Deaths were notified from linked national mortality statistics. Cox regression was used to estimate associations between delirium, frailty and their interactions on mortality.ResultsThe sample consisted of 710 individuals. Both delirium and frailty were independently associated with increased mortality rates (delirium: HR 2.4, 95%CI 1.8-3.3, p&lt;0.01; frailty (per SD): HR 3.5, 95%CI 1.2-9.9, p=0.02). Estimating the effect of delirium in tertiles of FI, mortality was greatest in the lowest tertile: tertile 1 HR 3.4 (95%CI 2.1-5.6); tertile 2 HR 2.7 (95%CI 1.5-4.6); tertile 3 HR 1.9 (95% CI 1.2-3.0).ConclusionWhile delirium and frailty contribute to mortality, the overall impact of delirium on admission appears to be greater at lower levels of frailty. In contrast to the hypothesis that there is a bimodal distribution for mortality, delirium appears to be particularly adverse when precipitated in fitter individuals.</jats:sec