Optimal learning for sequential sampling with non-parametric beliefs

We propose a sequential learning policy for ranking and selection problems, where we use a non-parametric procedure for estimating the value of a policy. Our estimation approach aggregates over a set of kernel functions in order to achieve a more consistent estimator. Each element in the kernel estimation set uses a different bandwidth to achieve better aggregation. The final estimate uses a weighting scheme with the inverse mean square errors of the kernel estimators as weights. This weighting scheme is shown to be optimal under independent kernel estimators. For choosing the measurement, we employ the knowledge gradient policy that relies on predictive distributions to calculate the optimal sampling point. Our method allows a setting where the beliefs are expected to be correlated but the correlation structure is unknown beforehand. Moreover, the proposed policy is shown to be asymptotically optimal.     

Development of one-pot benzylic amination reactions of azine N-oxides

An efficient one-pot synthetic methodology has been developed for the benzylic amination reactions of methyl-substituted azine N-oxides that operate under mild conditions. The reaction was found to tolerate quinoline and isoquinoline N-oxides with electron donating and withdrawing substituents as the electrophilic reaction partners as well as a broad range of nucleophilic primary, secondary and aromatic amines, affording the benzylic amination products in up to 82% yield.     

Simultaneous Identification of Spectral Properties and Sizes of Multiple Particles in Solution with Subnanometer Resolution

We report an unsurpassed solution characterization technique based on analytical ultracentrifugation, which demonstrates exceptional potential for resolving particle sizes in solution with sub‐nm resolution. We achieve this improvement in resolution by simultaneously measuring UV/Vis spectra while hydrodynamically separating individual components in the mixture. By equipping an analytical ultracentrifuge with a novel multi‐wavelength detector, we are adding a new spectral discovery dimension to traditional hydrodynamic characterization, and amplify the information obtained by orders of magnitude. We demonstrate the power of this technique by characterizing unpurified CdTe nanoparticle samples, avoiding tedious and often impossible purification and fractionation of nanoparticles into apparently monodisperse fractions. With this approach, we have for the first time identified the pure spectral properties and band‐gap positions of discrete species present in the CdTe mixture.     

On the Modeling of CO2 EUA and CER Prices of EU‐ETS for the 2008–2012 Period

Increased consumption of fossil fuels in industrial production has led to a significant elevation in the emission of greenhouse gases and to global warming. The most effective international action against global warming is the Kyoto Protocol, which aims to reduce carbon emissions to desired levels in a certain time span. Carbon trading is one of the mechanisms used to achieve the desired reductions. One of the most important implications of carbon trading for industrial systems is the risk of uncertainty about the prices of carbon allowance permits traded in the carbon markets. In this paper, we consider stochastic and time series modeling of carbon market prices and provide estimates of the model parameters involved, based on the European Union emissions trading scheme carbon allowances data obtained for 2008–2012 period. In particular, we consider fractional Brownian motion and autoregressive moving average–generalized autoregressive conditional heteroskedastic modeling of the European Union emissions trading scheme data and provide comparisons with benchmark models. Our analysis reveals evidence for structural changes in the underlying models in the span of the years 2008–2012. Data‐driven methods for identifying possible change‐points in the underlying models are employed, and a detailed analysis is provided. Our analysis indicated change‐points in the European Union Allowance (EUA) prices in the first half of 2009 and in the second half of 2011, whereas in the Certified Emissions Reduction (CER) prices three change‐points have appeared, in the first half of 2009, the middle of 2011, and in the second half of 2012. These change‐points seem to parallel the global economic indicators as well. Copyright © 2016 John Wiley & Sons, Ltd.     

Interfacial engineering of CuO nanorod/ZnO nanowire hybrid nanostructure photoanode in dye-sensitized solar cell

Developing efficient and cost-effective photoanode plays a vital role determining the photocurrent and photovoltage in dye-sensitized solar cells (DSSCs). Here, we demonstrate DSSCs that achieve relatively high power conversion efficiencies (PCEs) by using one-dimensional (1D) zinc oxide (ZnO) nanowires and copper (II) oxide (CuO) nanorods hybrid nanostructures. CuO nanorod-based thin films were prepared by hydrothermal method and used as a blocking layer on top of the ZnO nanowires’ layer. The use of 1D ZnO nanowire/CuO nanorod hybrid nanostructures led to an exceptionally high photovoltaic performance of DSSCs with a remarkably high open-circuit voltage (0.764 V), short current density (14.76 mA/cm² under AM1.5G conditions), and relatively high solar to power conversion efficiency (6.18%) . The enhancement of the solar to power conversion efficiency can be explained in terms of the lag effect of the interfacial recombination dynamics of CuO nanorod-blocking layer on ZnO nanowires. This work shows more economically feasible method to bring down the cost of the nano-hybrid cells and promises for the growth of other important materials to further enhance the solar to power conversion efficiency.     

Double Vivaldi antenna for wireless optical networks on chip

In this paper we present a double plasmonic Vivaldi antenna for on-chip optical wireless communication. The proposed antenna is a two-element broadside array fed by a silicon waveguide. The designs of the power splitter and of the hybrid Si-plasmonic coupler used for antenna excitation are described in detail. The array radiation characteristics are optimized through Finite Difference Time Domain simulations and the performance of a point-to-point link is evaluated. The proposed double Vivaldi array increases the gain of 3 dB with respect to a single antenna, improving the received power on a link of 6 dB when the double antenna is used for both transmitting and receiving sections.     

Tests of the CBM Rich readout and Daq prototype

The CBM RICH detector is an integral component of the future CBM experiment at FAIR, providing efficient electron identification and pion suppression necessary for the measurement of rare dileptonic probes in heavy ion collisions. An overview of the CBM RICH readout and DAQ system prototype is given, consisting of the PADIWA preamplifier-discriminator board, the TDC-HUB board TRBv3, and DAQ and analysis code in the CbmRoot framework. The laboratory setup built for studying the timing characteristics of the readout chain and the analysis results obtained using the laboratory measurements are presented. The fine time calibration and inter-channel delay correction techniques and their implementation and effect are discussed.     

Analysis of the alterations in porosity features of some natural stones due to thermal effect

Three types of commercially available carbonate rocks were used in the study to determine the effect of thermal treatment in the range from 100 °C to 500 °C on porosity features in terms of two different approaches such as pore shape factor and quality index values. The ratio of the ultrasonic velocity measurements before and after water saturation was used to differentiate porosity of pores from porosity of cracks under varying temperatures. It was found that, pores in Burdur Beige and Usak White are in the form of cracks, which are situated through inner structure. On the other hand, pores in Patara Limestone are in the form of porosity with lower pore shape factor values. Quality index calculation is another approach based on the comparison of the measured and theoretical ultrasonic velocity values. When the rocks were subjected to higher temperatures, internal stress was developed, crack lengths and numbers were increased and finally the higher pore shape factor and lower quality index values were obtained. This situation was proven by the higher water absorption values for all the stone types with the higher pore shape factor and lower quality index values depend on the noticeable increase in effective porosity values.     

Comparing the efficiencies of hydrazide labels in the study of protein carbonylation in human serum albumin

In this work, we establish a methodology for comparing the efficiencies of different hydrazide labels for detecting protein carbonyls. We have chosen acrolein-modified human serum albumin as a model. This system provides a convenient means of reproducibly generating carbonylated protein. Five hydrazide-based labels were tested. Three carry a biotin affinity tag, and the others are simple fatty acid hydrazides. For the biotin-based labels, the yield of the labeling reaction varies considerably, and the most commonly used label, biotin hydrazide, gives the lowest yield. The total tandem mass spectrometry (MS/MS) spectrum counts of modified peptides are similar for all of the biotin-based tags, indicating that factors beyond the labeling efficiency are important in determining the effectiveness of the label. In addition, there is a large variation in the number of spectra obtained for specific, modified peptides depending on the nature of the labeling group. This variation implies that the relative detectability of a particular modification site is highly dependent on the tagging reagent, and more importantly, titration schemes aimed at identifying the most reactive site based on its threshold concentration will be biased by the choice of tagging reagent. The fatty acid hydrazides are somewhat more effective than the biotin-based hydrazides in generating identifiable MS/MS spectra but offer no opportunity for enrichment. For the biotin-based tags, avidin affinity chromatography was used with the tryptic digests, and each tag led to similar enrichment levels.